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Dysregulated mitochondrial fusion and fission has been implicated in the pathogenesis of numerous diseases. We have identified a novel function of the p53 family protein TAp73 in regulating mitochondrial dynamics. TAp73 regulates the expression of Optic Atrophy 1 (OPA1), a protein responsible for controlling mitochondrial fusion, cristae biogenesis and electron transport chain function. Disruption of this axis results in a fragmented mitochondrial network and an impaired capacity for energy production via oxidative phosphorylation. Owing to the role of OPA1 in modulating cytochrome c release, TAp73 -/- cells display an increased sensitivity to apoptotic cell death, e.g., via BH3-mimetics. We additionally show that the TAp73/OPA1 axis has functional relevance in the upper airway, where TAp73 expression is essential for multiciliated cell differentiation and function. Consistently, ciliated epithelial cells of Trp73 -/- (global p73 knock-out) mice display decreased expression of OPA1 and perturbations of the mitochondrial network, which may drive multiciliated cell loss. In support of this, Trp73 and OPA1 gene expression is decreased in chronic obstructive pulmonary disease (COPD) patients, a disease characterised by alterations in mitochondrial dynamics. We therefore highlight a potential mechanism involving the loss of p73 in COPD pathogenesis. Our findings also add to the growing body of evidence for growth-promoting roles of TAp73 isoforms., (© 2024. The Author(s).)

Outer mitochondrial membrane fusion, a vital cellular process, is mediated by mitofusins. However, the underlying molecular mechanism remains elusive. We have performed extensive multiscale molecular dynamics simulations to predict a model of the transmembrane (TM) domain of the yeast mitofusin Fzo1. Coarse-grained simulations of the two TM domain helices, TM1 and TM2, reveal a stable interface, which is controlled by the charge status of residue Lys716. Atomistic replica-exchange simulations further tune our model, which is confirmed by a remarkable agreement with an independent AlphaFold2 (AF2) prediction of Fzo1 in complex with its fusion partner Ugo1. Furthermore, the presence of the TM domain destabilizes the membrane, even more if Lys716 is charged, which can be an asset for initiating fusion. The functional role of Lys716 was confirmed with yeast experiments, which show that mutating Lys716 to a hydrophobic residue prevents mitochondrial fusion., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In the budding yeast Saccharomyces cerevisiae , exit from mitosis is coupled to spindle position to ensure successful genome partitioning between mother and daughter cells. This coupling occurs through a GTPase signaling cascade known as the mitotic exit network (MEN). The MEN senses spindle position via a Ras-like GTPase Tem1 which localizes to the spindle pole bodies (SPBs, yeast equivalent of centrosomes) during anaphase and signals to its effector protein kinase Cdc15. How Tem1 couples the status of spindle position to MEN activation is not fully understood. Here, we show that Cdc15 has a relatively weak preference for Tem1 GTP and Tem1's nucleotide state does not change upon MEN activation. Instead, we find that Tem1's nucleotide cycle establishes a localization-based concentration difference in the cell where only Tem1 GTP is recruited to the SPB, and spindle position regulates the MEN by controlling Tem1 localization to the SPB. SPB localization of Tem1 primarily functions to promote Tem1-Cdc15 interaction for MEN activation by increasing the effective concentration of Tem1. Consistent with this model, we demonstrate that artificially tethering Tem1 to the SPB or concentrating Tem1 in the cytoplasm with genetically encoded multimeric nanoparticles could bypass the requirement of Tem1 GTP and correct spindle position for MEN activation. This localization/concentration-based GTPase signaling mechanism for Tem1 differs from the canonical Ras-like GTPase signaling paradigm and is likely relevant to other localization-based signaling scenarios., Competing Interests: Competing interests statement:The authors declare no competing interest.

Mitochondrial dynamics and mitophagy are intimately linked physiological processes that are essential for cardiac homeostasis. Here we show that cardiac Krüppel-like factor 9 (Klf9) is dysregulated in human and rodent cardiomyopathy. Both global and cardiac-specific Klf9-deficient mice displayed hypertrophic cardiomyopathy. Klf9 knockout led to mitochondrial disarray and fragmentation, impairing mitochondrial respiratory function in cardiomyocytes. Furthermore, cardiac Klf9 deficiency inhibited mitophagy, thereby causing accumulation of dysfunctional mitochondria and acceleration of heart failure in response to angiotensin II treatment. In contrast, cardiac-specific Klf9 transgene improved cardiac systolic function. Mechanistically, Klf9 knockout decreased the expression of PGC-1α and its target genes involved in mitochondrial energy metabolism. Moreover, Klf9 controlled the expression of Mfn2, thereby regulating mitochondrial dynamics and mitophagy. Finally, adeno-associated virus-mediated Mfn2 rescue in Klf9-CKO hearts improved cardiac mitochondrial and systolic function. Thus, Klf9 integrates cardiac energy metabolism, mitochondrial dynamics and mitophagy. Modulating Klf9 activity may have therapeutic potential in the treatment of heart failure., Competing Interests: Competing interests All authors declare no competing interests. There are no conflicts of interest in the submission of this manuscript, which was approved by all authors for publication. We also confirm that this work is original. It has not been published elsewhere and is not currently under consideration for publication elsewhere., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Genomic profiles and prognostic biomarkers in patients with acute myeloid leukemia (AML) from ancestry-diverse populations are underexplored. We analyzed the exomes and transcriptomes of 100 patients with AML with genomically confirmed African ancestry (Black; Alliance) and compared their somatic mutation frequencies with those of 323 self-reported white patients with AML, 55% of whom had genomically confirmed European ancestry (white; BeatAML). Here we find that 73% of 162 gene mutations recurrent in Black patients, including a hitherto unreported PHIP alteration detected in 7% of patients, were found in one white patient or not detected. Black patients with myelodysplasia-related AML were younger than white patients suggesting intrinsic and/or extrinsic dysplasia-causing stressors. On multivariable analyses of Black patients, NPM1 and NRAS mutations were associated with inferior disease-free and IDH1 and IDH2 mutations with reduced overall survival. Inflammatory profiles, cell type distributions and transcriptional profiles differed between Black and white patients with NPM1 mutations. Incorporation of ancestry-specific risk markers into the 2022 European LeukemiaNet genetic risk stratification changed risk group assignment for one-third of Black patients and improved their outcome prediction., (© 2024. The Author(s).)

Background: Frailty increases the incidence of geriatric syndromes and even the risk of death in old adults. However, the diagnostic criteria for frailty are inconsistent because of complex pathological processes and diverse clinical manifestations. To determine the effective biomarker and recognize frail status early, we investigated the correlation of mitochondrial morphology and function of human peripheral blood mononuclear cells (PBMCs) with frailty status in older adults., Methods: This Cross-sectional study followed 393 participants (aged 25-100 years, female 31.04 %) from the First Affiliated Hospital of Nanjing Medical University. The frailty status of subjects was assessed by the physical frailty phenotype (PFP) scale. We analyzed mitochondria functions including mitochondria copy number (mtDNAcn), the mRNA expressions of mitochondrial dynamics-related genes mitofusin 1(MFN1), mitofusin 2(MFN2), optic atrophy protein-1(OPA1), fission protein-1(FIS1) and dynamin-related protein 1(DRP1), mitochondrial oxidative respiration and reactive oxygen species(ROS) levels in PBMCs. Mitochondria morphology, size, and number were observed by transmission electron microscopy (TEM)., Results: After adjustment for sex and BMI, mtDNAcn, the mRNA expression of FIS1, mitochondrial respiratory function (proton leak, maximum oxygen consumption, and respiratory reserve) and ROS level were significantly correlated with age (P = 0.031, 0.030, 0.042, 0.003, 0.002, 0.022, respectively). After correcting for age, sex, and BMI, mtDNAcn and the mRNA expression of OPA1 were correlated with 4 m gait speed respectively (P = 0.003, 0.028, respectively). Compared with non-frail people, mtDNAcn, the mRNA expression of MFN1, mitochondrial basal respiration, proton leak, maximum oxygen consumption, ATP production and space capacity were significantly decreased in frail older adults (P = 0.013, 0.036, 0.026, 0.024, 0.012, 0.032, 0.020, respectively). ROS levels were significantly increased in the frail group (P = 0.016). Compared with non-frail people, the number, length, and perimeter, area of mitochondria were reduced in frail group under TEM (all P < 0.001)., Conclusion: Mitochondrial dysfunctions (decreased mtDNAcn, impaired mitochondrial morphology, imbalanced mitochondrial dynamic, impaired mitochondrial respiratory function, and increased ROS levels) were significantly correlated with frail status., Competing Interests: Declaration of competing interest We declare no competing interests., (Copyright © 2024. Published by Elsevier Inc.)

Acute myeloid leukemia (AML) cells are highly dependent on oxidative phosphorylation and the mitochondrial dynamics regulated by fusion-related genes MFN1, MFN2, and OPA1 and fission-related genes DNM1L and MFF. An analysis of previously published gene expression datasets showed that high expression of MFF was significantly associated with poor prognosis in patients with AML. Based on this finding, we investigated the impact of mitochondrial dynamics in AML. Transduction of shRNA against fission-related genes, DNM1L and MFF, inhibited growth and increased the mitochondrial area in AML cell lines. Extracellular flux analysis showed that deletion of mitochondrial dynamic regulators reduced mitochondrial respiration without significantly affecting glycolysis, except in shDNM1L-transfected cells. Immunodeficient NOG mice transplanted with DNM1L- or MFF-knockdown AML cells survived significantly longer than controls. Treatment of AML cell lines with Mdivi-1, which inhibits the DRP1 encoded by DNM1L, inhibited cell proliferation and oxidative phosphorylation. Our results show that mitochondrial dynamics play an important role in AML, and provide novel biological insights. The inhibition of mitochondrial dynamics induces unique mitochondrial alterations, which may be explored as a potential therapeutic target in AML., (© 2024. Japanese Society of Hematology.)

The Neuroblastoma RAS (NRAS) oncogene homologue plays crucial roles in diverse cellular processes such as cell proliferation, survival, and differentiation. Several strategies have been developed to inhibit NRAS or its downstream effectors; however, there is no effective drug available to treat NRAS-driven cancers and thus new approaches are needed to be established. The mRNA sequence expressing NRAS containing several guanine(G)-rich regions may form quadruplex structures (G4s) and regulate NRAS translation. Therefore, targeting NRAS mRNA G4s to repress NRAS expression at translational level with ligands may be a feasible strategy against NRAS-driven cancers but it is underexplored. We reported herein a NRAS mRNA G4-targeting ligand, B3C, specifically localized in cytoplasm in HeLa cells. It effectively downregulates NRAS proteins, reactivates the DNA damage response (DDR), causes cell cycle arrest in G 2 /M phase, and induces apoptosis and senescence. Moreover, combination therapy with NARS mRNA G4-targeting ligands and clinical PI3K inhibitors for cancer cells inhibition treatment is unexplored, and we demonstrated that B3C combining with PI3Ki (pictilisib (GDC-0941)) showed potent antiproliferation activity against HeLa cells (IC 50  = 1.03 μM (combined with 10 μM PI3Ki) and 0.42 μM (combined with 20 μM PI3Ki)) and exhibited strong synergistic effects in inhibiting cell proliferation. This study provides new insights into drug discovery against RAS-driven cancers using this conceptually new combination therapy strategy., Competing Interests: Declaration of competing interest Authors declare that they do not have any financial or commercial interest regarding this article., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Leptomeningeal melanoma metastases (LMM) are associated with poor survival. Diagnosis is based on clinical presentation, brain MRI and cerebrospinal fluid (CSF) analysis. Inconclusive findings at initial presentation can delay treatment. In this single-center case series, detection of BRAF V600 - and NRAS Q61 -mutant cell-free tumor DNA (cfDNA) in CSF was evaluated as a complementary diagnostic biomarker. In 12 patients with clinical suspicion of LMM, a retrospective analysis of MRI, CSF cytology and cfDNA analysis on 1 mL of CSF using the Idylla® platform was carried out. Nine patients displayed MRI abnormalities suggesting LMM. CSF analysis identified malignant cells in three patients (including one without MRI abnormalities). BRAF V600 - or NRAS Q61 -mutant cfDNA was detected in CSF of nine patients (eight with and one without MRI abnormalities; all patients with positive CSF cytology). Subsequent follow-up confirmed LMM in all patients with positive and in one patient with a negative CSF cfDNA analysis (sensitivity 81.8%; specificity 100%). Our findings suggest that analyzing BRAF V600 - and NRAS Q61 -mutant cfDNA in CSF using the Idylla® platform holds promise as a sensitive and specific complementary diagnostic biomarker for LMM, particularly in case of inconsistency between imaging and CSF cytology. The 110-min analysis can facilitate urgent treatment decisions., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: To perform a molecular profiling of the metastases from papillary thyroid carcinomas (PTCs) and poorly differentiated thyroid carcinomas (PDTCs)., Methods: We retrieved and analyzed the molecular and clinical features of 136 metastases from PTCs and 35 metastases from PDTCs subjected to targeted DNA sequencing, from cBioPortal. The clinicopathological data included the number and location of the metastases, and genomic data included mutations, translocations, copy number alterations and fraction of the genome altered (FGA)., Results: Bone metastases from PTCs had a lower frequency of BRAF mutations than the lymph node metastases (LNMs) (43% vs 88%, p < 0.01), and a higher frequency of RBM10 and NRAS mutations than the LNMs (21% vs 3% for both, p < 0.05). The FGA of the bone metastases was higher than the FGA of the lung metastases (5.6% vs 1.3%, p < 0.05). The frequency of RET translocations was higher in the lung metastases from PTCs than the LNMs (15% vs 3%, p < 0.05). The LNMs from PTC patients harboring 4 or more distant metastases (DMs) had a higher frequency of TERT promoter mutations than the LNMs from patients harboring less than 4 DMs (96% vs 65%, p < 0.001). SDHA gene amplifications were enriched in the bone metastases from PDTCs and absent in the LNMs (38% vs 0%, p < 0.05)., Conclusion: Metastases from PTCs and PDTCs harbor clinically relevant alterations affecting distinct body locations, such as NRAS and RBM10 mutations, RET translocations and SDHA amplifications that may be explored therapeutically., (© 2024. The Author(s).)

Neuregulin 4 (Nrg4) is an adipokine that belongs to the epidermal growth factor family and binds to ErbB4 tyrosine kinase receptors. In 3T3-L1 adipocytes, the downregulation of Nrg4 expression enhances inflammation and autophagy, resulting in insulin resistance. Here, we searched for the causes of this phenotype. Nrg4 knockdown (Nrg4 KD) adipocytes showed a significant reduction in mitochondrial content and elongation, along with a lower content of the mitochondria fusion protein mitofusin 2 (MFN2), and increased H 2 O 2 production compared to the control scrambled cells (Scr). The antioxidant N-acetylcysteine reversed the oxidative stress and reduced the gene expression of the pro-inflammatory cytokine tumor necrosis factor α (TNFα). Nrg4 KD adipocytes showed enhanced lipolysis and reduced lipogenesis, in addition to a significant reduction in several intermediates of the Krebs cycle. In summary, Nrg4 downregulation in adipocytes affects mitochondrial content and functioning, causing impaired cellular metabolism, which in turn results in oxidative stress, inflammation, and insulin resistance.

The eIF4F translation initiation complex plays a critical role in melanoma resistance to clinical BRAF and MEK inhibitors. In this study, we uncover a function of eIF4F in the negative regulation of the rat sarcoma (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) signaling pathway. We demonstrate that eIF4F is essential for controlling ERK signaling intensity in treatment-naïve melanoma cells harboring BRAF or NRAS mutations. Specifically, the dual-specificity phosphatase DUSP6/MKP3, which acts as a negative feedback regulator of ERK activity, requires continuous production in an eIF4F-dependent manner to limit excessive ERK signaling driven by oncogenic RAF/RAS mutations. Treatment with small-molecule eIF4F inhibitors disrupts the negative feedback control of MAPK signaling, leading to ERK hyperactivation and EGR1 overexpression in melanoma cells in vitro and in vivo. Furthermore, our quantitative analyses reveal a high spare signaling capacity in the ERK pathway, suggesting that eIF4F-dependent feedback keeps the majority of ERK molecules inactive under normal conditions. Overall, our findings highlight the crucial role of eIF4F in regulating ERK signaling flux and suggest that pharmacological eIF4F inhibitors can disrupt the negative feedback control of MAPK activity in melanomas with BRAF and NRAS activating mutations., Competing Interests: Competing interests statement:The authors declare no competing interest.

Osteoarthritis (OA) is an age-related cartilage-degenerating joint disease. Mitochondrial dysfunction has been reported to promote the development of OA. Poly (ADP-ribose) polymerase family member 12 (PARP12) is a key regulator of mitochondrial function, protein translation, and inflammation. However, the role of PARP12 in OA-based cartilage degradation and the underlying mechanisms are relatively unknown. Here, we first demonstrated that PARP12 inhibits mitophagy and promotes OA progression in human OA cartilage and a monosodium iodoacetate-induced rat OA model. Using mass spectrometry and co-immunoprecipitation assay, PARP12 was shown to interact with ISG15, upregulate mitofusin 1 and 2 (MFN1/2) ISGylation, which downregulated MFN1/2 ubiquitination and SUMOylation, thereby inhibiting PINK1/Parkin-dependent chondrocyte mitophagy and promoting cartilage degradation. Moreover, inflammatory cytokine-induced interferon regulatory factor 1 (IRF1) activation was required for the upregulation of PARP12 expression, and it directly bound to the PARP12 promoter to activate transcription. XAV-939 inhibited PARP12 expression and suppressed OA pathogenesis in vitro and in vivo. Clinically, PARP12 can be used to predict the severity of OA; thus, it represents a new target for the study of mitophagy and OA progression. In brief, the IRF1-mediated upregulation of PARP12 promoted cartilage degradation by inhibiting PINK1/Parkin-dependent mitophagy via ISG15-based attenuation of MFN1/2 ubiquitylation and SUMOylation. Our data provide new insights into the molecular mechanisms underlying PARP12-based regulation of mitophagy and can facilitate the development of therapeutic strategies for the treatment of OA., (© 2024. The Author(s).)

In cancer research, RAS biology has been focused on only a handful of tumor types. While RAS genes have long been suspected as common contributors to a wide spectrum of cancer types, robust evidence is required to firmly establish their critical oncogenic significance. We present a data mining study using DepMap genome-wide CRISPR screening data, which provide substantial evidence to support the prominent pervasive oncogenic role and tissue-specific permissiveness of RAS gene mutations. Differential analysis of CRISPR effect scores identifies K- or N-RAS genes as the most differential gene in contrasts of (K-, N-, combined) RAS mutant versus wild-type cell lines across multiple tissue types. The distinguished tissue-specific pattern of KRAS vs. NRAS as top differential genes in subsets of tissue types and evidence from genome data supported the idea of KRAS- and NRAS-engaged tissue types. To our knowledge, this is the first report of prominent pervasive oncogenic role of RAS mutations revealed by gene dependency data that is beyond the current understanding of the oncogenic role of RAS genes and their well-known involved tissue types. Our findings strongly support RAS mutations as primary oncogenic drivers beyond traditionally recognized cancer types and offer insights into their tissue-specific permissiveness., (© 2024. The Author(s).)

Mitochondrial dysfunction is a hallmark of many genetic neurodegenerative diseases, but therapeutic options to reverse mitochondrial dysfunction are limited. While recent studies support the possibility of improving mitochondrial fusion/fission dynamics and motility to correct mitochondrial dysfunction and resulting neurodegeneration in Charcot-Marie-Tooth disease (CMT) and other neuropathies, the clinical utility of reported compounds and relevance of preclinical models are uncertain. Here, we describe motor and sensory neuron dysfunction characteristic of clinical CMT type 2 A in a CRISPR/Casp-engineered Mfn2 Thr105Met (T105M) mutant knock-in mouse. We further demonstrate that daily oral treatment with a novel mitofusin activator derived from the natural product piperine can reverse these neurologic phenotypes. Piperine derivative 8015 promoted mitochondrial fusion and motility in Mfn2-deficient cells in a mitofusin-dependent manner and reversed mitochondrial dysfunction in cultured fibroblasts and reprogrammed motor neurons from a human CMT2A patient carrying the MFN2 T105M mutation. Like previous mitofusin activators, 8015 exhibited stereospecific functionality, but the more active stereoisomer, 8015-P2, is unique in that it has subnanomolar potency and undergoes entero-hepatic recirculation which extends its in vivo half-life. Daily administration of 8015-P2 to Mfn2 T105M knock-in mice for 6 weeks normalized neuromuscular and sensory dysfunction and corrected histological/ultrastructural neurodegeneration and neurogenic myoatrophy. These studies describe a more clinically relevant mouse model of CMT2A and an improved mitofusin activator derived from piperine. We posit that 8015-P2 and other piperine derivatives may benefit CMT2A or other neurodegenerative conditions wherein mitochondrial dysdynamism plays a contributory role. SIGNIFICANCE STATEMENT: Mitochondrial dysfunction is widespread and broadly contributory in neurodegeneration, but difficult to target therapeutically. Here, we describe 8015-P2, a new small molecule mitofusin activator with ∼10-fold greater potency and improved in vivo pharmacokinetics versus comparators, and demonstrate its rapid reversal of sensory and motor neuron dysfunction in an Mfn2 T105M knock-in mouse model of Charcot-Marie-Tooth disease type 2 A. These findings further support the therapeutic approach of targeting mitochondrial dysdynamism in neurodegeneration., (Copyright © 2024 by The Author(s).)

Huntington's Disease (HD) is an inheritable neurodegenerative condition caused by an expanded CAG trinucleotide repeat in the HTT gene with a direct correlation between CAG repeats expansion and disease severity with earlier onset-of- disease. Previously we have shown that primary skin fibroblasts from HD patients exhibit unique phenotype disease features, including distinct nuclear morphology and perturbed actin cap linked with cell motility, that are correlated with the HD patient disease severity. Here we provide further evidence that mitochondrial fission-fusion morphology balance dynamics, classified using a custom image-based high-content analysis (HCA) machine learning tool, that improved correlation with HD severity status. This mitochondrial phenotype is supported by appropriate changes in fission-fusion biomarkers (Drp1, MFN1, MFN2, VAT1) levels in the HD patients' fibroblasts. These findings collectively point towards a dysregulation in mitochondrial dynamics, where both fission and fusion processes may be disrupted in HD cells compared to healthy controls. This study shows for the first time a methodology that enables identification of HD phenotype before patient's disease onset (Premanifest). Therefore, we believe that this tool holds a potential for improving precision in HD patient's diagnostics bearing the potential to evaluate alterations in mitochondrial dynamics throughout the progression of HD, offering valuable insights into the molecular mechanisms and drug therapy evaluation underlying biological differences in any disease stage., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

NRAS belongs to the RAS family of GTPases. In colorectal cancer (CRC), NRAS mutations are rare compared to KRAS, but may lead to worse outcomes. We report the functional characterization of the novel NRAS mutants-G48C, Q43K, and E37K-identified in Filipino young-onset CRC patients. Unlike previously characterized NRAS mutants with no apparent effects on cell proliferation, these mutants enhanced proliferation of both HCT116 and NIH3T3 cells. This was confirmed in 3D spheroid assays to mimic the spatial organization of cells. G48C and E37K showed apoptosis resistance in both cell lines, and Q43K showed resistance in HCT116 cells. All three showed no effect on cellular migration in NIH3T3, but G48C enhanced the migration rate of HCT116 cells. Actin staining of NIH3T3 cells expressing the mutants showed a shrunken cytoplasm and transient structures associated with motility and invasiveness. Docking simulations show that GDP is only able to bind fully within the binding pocket of wild-type NRAS, but not in the mutants. Further, G48C, Q43K, and E37K all have less negative ΔG values, indicating a weaker GDP-binding affinity compared to wild-type NRAS. Taken together, the results suggest that oncogenic readouts of NRAS mutants are codon- and mutation-specific, with potential repercussions on the aggressiveness, resistance, and therapeutic response.

Mitochondrial functions can be regulated by membrane contact sites with the endoplasmic reticulum (ER). These mitochondria-ER contact sites (MERCs) are functionally heterogeneous and maintained by various tethers. Here, we found that REEP5, an ER tubule-shaping protein, interacts with Mitofusins 1/2 to mediate mitochondrial distribution throughout the cytosol by a new transport mechanism, mitochondrial "hitchhiking" with tubular ER on microtubules. REEP5 depletion led to reduced tethering and increased perinuclear localization of mitochondria. Conversely, increasing REEP5 expression facilitated mitochondrial distribution throughout the cytoplasm. Rapamycin-induced irreversible REEP5-MFN1/2 interaction led to mitochondrial hyperfusion, implying that the dynamic release of mitochondria from tethering is necessary for normal mitochondrial distribution and dynamics. Functionally, disruption of MFN2-REEP5 interaction dynamics by forced dimerization or silencing REEP5 modulated the production of mitochondrial reactive oxygen species (ROS). Overall, our results indicate that dynamic REEP5-MFN1/2 interaction mediates cytosolic distribution and connectivity of the mitochondrial network by "hitchhiking" and this process regulates mitochondrial ROS, which is vital for multiple physiological functions., (© 2024 Chen et al.)

Introduction: Bladder cancer (BCa) is a common malignancy in the urinary tract. It has high recurrence rates and often requires microscopic examination, which presents significant challenges in clinical treatment. Previous research has shown that circular TAF4B (circTAF4B) is significantly upregulated in BCa and is associated with a poor prognosis. However, the specific targets and molecular mechanisms by which circTAF4B functions in BCa are still not well - understood., Methods: In this study, an RNA pull - down assay and mass spectrometry were utilized to identify MFN2 as a binding protein of circTAF4B. Additionally, siRNA was used to silence MFN2 to observe the amplification of the inhibitory effects of circTAF4B overexpression on cell growth and migration in BCa cells. Moreover, circTAF4B shRNA lentiviral particles were employed to study their impact on BCa progression by examining the regulation of p27 and the blocking of AKT signaling., Results: It was found that MFN2 is a binding protein of circTAF4B. Silencing MFN2 with siRNA enhanced the inhibitory effects of circTAF4B overexpression on cell growth and migration in BCa cells. Also, circTAF4B shRNA lentiviral particles inhibited BCa progression by upregulating p27 and blocking AKT signaling., Discussion: In conclusion, the physical binding of circTAF4B to MFN2 is a crucial process in the tumorigenesis and progression of BCa. Targeting circTAF4B or its complexes may have potential as a therapeutic strategy for BCa diagnosis and treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhang, Xu, Zhuang, Wang, Li and Zhu.)

This study aims to describe the ophthalmic characteristics of autosomal dominant (AD) WFS1-associated optic atrophy (AD WFS1-OA), and to explore phenotypic differences with dominant optic atrophy (DOA) caused by mutations in the OPA1-gene. WFS1-associated diseases, or 'wolframinopathies', exhibit a spectrum of ocular and systemic phenotypes, of which the autosomal recessive Wolfram syndrome has been the most extensively studied. AD mutations in WFS1 also cause various phenotypical changes including OA. The most common phenotype in AD WFS1-associated disease, the combination of OA and hearing loss (HL), clinically resembles the 'plus' phenotype of DOA. We performed a comprehensive medical record review across tertiary referral centers in the Netherlands and Belgium resulting in 22 patients with heterozygous WFS1 variants. Eighteen (82%) had HL in addition to OA. Diabetes mellitus was found in 7 (32%). Four patients had isolated OA. One patient had an unusual phenotype with anterior chamber abnormalities and malformations of the extremities. Compared to DOA, AD WFS1-OA patients had different color vision abnormalities (red-green vs blue-yellow in DOA), abnormal OPL lamination on macular OCT (absent in DOA), more generalized thinning of the retinal nerve fiber layer, and more reduced and delayed pattern reversal visual evoked potentials., (© 2024. The Author(s).)

Background: Melanomas are rare yet the most aggressive skin cancer among Asians. Clinical presentation, risk factors, and the underlying molecular mechanisms are strikingly different from cutaneous melanoma in Caucasians., Methods: Mutation patterns of BRAF and NRAS genes were examined from DNAs derived from primary melanoma tumor tissues (fresh tissues or formalin-fixed paraffin-embedded samples) using pyrosequencing., Results: A total of 63 patients consisting of acral lentiginous melanoma (N=22, 34.9%) and nodular melanoma (N=41, 65.1%) were included in this study. Most patients were diagnosed at Stage III-IV (N=49, 77.8%), Breslow thickness more than 4 mm (N=51, 80.9%), presence of ulceration (N=35, 55.6%), diameter larger than 6 mm (N=61, 96.8%), regional node infiltration (N=41, 77.8%). BRAF and NRAS mutations were found in 28 (44.4%) and 8 (12.7%), respectively. BRAF and NRAS mutations were significantly associated with older melanoma patients (OR = 6.075, 95%CI = 2.013-18.333 dan OR = 13.263, 95%CI = 1.518-115.901, respectively). BRAF mutations were associated with lower overall survival (Median survivals were 16.5 vs 31.4 months, Log-rank test P=0.001). NRAS mutations were not significantly associated with lower overall survival., Conclusion: In this study, melanoma patients are largely diagnosed at the late stages with ulceration and involvement of regional lymph nodes. BRAF mutations are associated with lower survival of cutaneous melanoma patients.

Objective: Acute respiratory distress syndrome (ARDS) patients currently have relatively high mortality, which is associated with early lung fibrosis. This study aimed to investigate whether miR-17 suppression could alleviate ARDS-associated lung fibrosis by regulating Mfn2., Methods: A mouse model of ARDS-related lung fibrosis was constructed via intratracheal instillation of bleomycin. The expression level of miR-17 in lung tissues was detected via quantitative real time polymerase chain reaction (qRT-PCR). In the ARDS mouse model of lung fibrosis, the mitigating effects of miR-17 interference were evaluated via tail vein injection of the miR negative control or the miR-17 antagomir. The pathological changes in the lung tissue were examined via HE staining and Masson's trichrome staining, and the underlying molecular mechanism was investigated via ELISA, qRT-PCR and Western blotting., Results: Bleomycin-induced pulmonary fibrosis significantly increased collagen deposition and the levels of hydroxyproline (HYP) and miR-17. Interfering with miR-17 significantly reduced the levels of HYP and miR-17 and upregulated the expression of Mfn2. The intravenous injection of the miR-17 antagomir alleviated lung inflammation and reduced collagen deposition. In addition, interference with miR-17 could upregulate LC3B expression, downregulate p62 expression, and improve mitochondrial structure., Conclusion: Interfering with miR-17 can improve pulmonary fibrosis in mice by promoting mitochondrial autophagy via Mfn2., (© 2024. Huazhong University of Science and Technology.)

Purpose: The prognostic and predictive value of RAS mutations in patients with colorectal liver metastases (CRLM) who have undergone hepatectomy holds substantial importance. The present study aimed to investigate the impact of different RAS codon mutations on long-term survival in CRLM patients., Methods: A retrospective analysis was conducted on clinicopathological data from 399 CRLM patients with RAS mutations who underwent hepatectomy between January 2000 and December 2020. The RAS mutation gene status was assessed in KRAS codons (G12, G13, Q61, and A146) and NRAS codons (G12, G13, and Q61). Survival curves were generated using the Kaplan-Meier plotter and compared using the log-rank test. Univariate and multivariate analyses were performed to analyze the clinicopathological data., Results: In the entire cohort, patients with KRAS G12 mutations exhibited the most favorable prognosis (p = 0.018). Comparatively, patients harboring KRAS Q61 mutations experienced poorer overall survival (OS) with a median of 15 months versus 33 months (p = 0.011) when compared to those with KRAS G12 mutations. Moreover, patients with NRAS Q61 mutations also showed decreased OS with a median of 26 months versus 33 months (p = 0.020) in comparison to KRAS G12 mutation patients. The results of multivariate analysis showed that both KRAS Q61 mutation (HR 2.130; 95% CI 1.088-4.168; p = 0.027) and NRAS Q61 mutation (HR 2.877; 95% CI 1.398-5.922; p = 0.004) were independent influencing factors of OS. Based on all identified risk factors, patients with RAS mutation were divided into high-risk and low-risk groups. Notably, in the high-risk group, the incorporation of postoperative chemotherapy was associated with longer OS, while it did not improve the survival of patients in the low-risk group., Conclusions: KRAS Q61 and NRAS Q61 mutations are promising predictors for OS in CRLM patients after hepatectomy. Postoperative chemotherapy may significantly benefit CRLM patients with RAS mutations, particularly those identified as high-risk., (© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.)

Purpose: Patients with BRAF V600 / NRAS Q61 wild-type melanoma who progress after immune checkpoint inhibitors (ICIs) have a poor prognosis. MEK inhibition has shown activity in this patient population but is associated with treatment-limiting skin toxicity. Combining a BRAF inhibitor with a MEK inhibitor is associated with less skin toxicity., Methods: This phase II trial investigated trametinib (2 mg once daily) in patients with advanced BRAF V600 / NRAS Q61 wild-type, ICI-refractory melanoma. In case of treatment-limiting skin toxicity, low-dose dabrafenib (50 mg twice daily) was added to trametinib. After a trial amendment, both drugs were combined up-front. The confirmed objective response rate (cORR) served as the primary end point., Results: Twenty-four patients were included (50% male; median age 57 years; 92% Eastern Cooperative Oncology Group Performance Status 0-2; 75% stage IV-M1c/stage IV-M1d; median number of prior therapies: two [range, 1-5]). Three patients were enrolled before and 21 patients after the amendment, respectively. Seven confirmed and one unconfirmed partial responses (PRs) were observed (cORR, 29.2%). The median duration of response was 16.6 weeks (95% CI, 5.5 to 27.7). Stable disease (SD) was the best response in an additional five patients. Among the responding patients, genetic alterations causing mitogen-activated protein kinase (MAPK) pathway activation were documented in six patients. The disease control rate in patients with MAPK pathway-activating alterations was 64.3% (five confirmed PR, one unconfirmed PR, and three SD). The median progression-free survival was 13.3 weeks (95% CI, 3.5 to 23.1), and the median overall survival was 54.3 weeks (95% CI, 37.9 to 70.6). Adding low-dose dabrafenib to trametinib effectively mitigated or prevented treatment-limiting trametinib-related skin toxicity., Conclusion: The combination of trametinib plus low-dose dabrafenib demonstrated encouraging efficacy and effective mitigation of skin toxicity in patients with advanced, ICI-pretreated BRAF V600 / NRAS Q61 wild-type melanoma patients. MAPK pathway-activating alterations hold promise as a predictive biomarker.

Autosomal dominant optic atrophy (ADOA) is an inherited optic neuropathy most frequently associated with OPA1 mutations. Most variants result in haploinsufficiency, and patient cells express roughly half of the normal levels of OPA1 protein. OPA1 is a mitochondrial GTPase that is essential for normal mitochondrial function. We identified and characterized STK-002, an antisense oligonucleotide (ASO) designed to prevent the incorporation of a naturally occurring alternatively spliced nonproductive exon in OPA1 . STK-002 dose dependently reduced the inclusion of this exon, and increased OPA1 protein in human cells, including ADOA patient-derived fibroblasts. ADOA patient cells manifest reduced mitochondrial respiration, and treatment with STK-002 improved the parameters of mitochondrial respiratory function in these cells. Since STK-002 increases OPA1 through the wild-type allele, we assessed retinal OPA1 in wild-type cynomolgus monkeys and rabbits after intravitreal administration of STK-002 or a rabbit-specific surrogate. Increased OPA1 protein was produced in retinal tissue in both species at 4 weeks after ASO injection and persisted in monkeys at 8 weeks. STK-002 and enhanced OPA1 immunofluorescence were visualized in retinal ganglion cells of cynomolgus monkeys treated with the ASO. Cumulatively, these data support the progression of STK-002 toward the clinic as the first potential disease-modifying treatment for ADOA.

Alveolar macrophages (AM) are key effectors of the immune response and are essential for host responses to S. pneumoniae. Mitochondria are highly dynamic organelles whose function aids in regulating the cell cycle, innate immunity, autophagy, redox signaling, calcium homeostasis, and mitochondrial quality control in AM. In response to cellular stress, mitochondria can engage in stress-induced mitochondrial hyperfusion (SIMH). The current study aimed to investigate the role of Mfn1 on mitochondrial control of reactive oxygen species (ROS) in AMs and the role of Mfn1 deficiency on immune responses to S. pneumoniae. Compared to Mfn1 FloxCre- controls, there were distinct histological differences in lung tissue collected from Mfn1 Floxed; CreLysM mice, with less injury and inflammation observed in mice with Mfn1 deficient myeloid cells. There was a significant decrease in lipid peroxidation and ROS production in Mfn1 deficient AM that was associated with increased superoxide dismutase (SOD) and antioxidant activity. Our findings demonstrate that Mfn1 deficiency in myeloid cells decreased inflammation and lung tissue injury during S. pneumoniae infection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Aberrant mitochondrial fission/fusion dynamics are frequently associated with pathologies, including cancer. We show that alternative splice variants of the fission protein Drp1 (DNM1L) contribute to the complexity of mitochondrial fission/fusion regulation in tumor cells. High tumor expression of the Drp1 alternative splice variant lacking exon 16 relative to other transcripts is associated with poor outcome in ovarian cancer patients. Lack of exon 16 results in Drp1 localization to microtubules and decreased association with mitochondrial fission sites, culminating in fused mitochondrial networks, enhanced respiration, changes in metabolism, and enhanced pro-tumorigenic phenotypes in vitro and in vivo. These effects are inhibited by siRNAs designed to specifically target the endogenously expressed transcript lacking exon 16. Moreover, lack of exon 16 abrogates mitochondrial fission in response to pro-apoptotic stimuli and leads to decreased sensitivity to chemotherapeutics. These data emphasize the pathophysiological importance of Drp1 alternative splicing, highlight the divergent functions and consequences of changing the relative expression of Drp1 splice variants in tumor cells, and strongly warrant consideration of alternative splicing in future studies focused on Drp1., (© 2024. The Author(s).)

The incidence and prevalence of melanoma are increasing globally, presenting a significant public health concern. The main genetic drivers of melanoma include BRAF, NRAS, KIT and triple wild-type (TWT) mutations. Little is known about the effects of these mutations on outcomes in terms of demographics and patient characteristics. We examined differences in melanoma mortality risk and mutation count across mutation type and patient disease profile. We extrapolated primary melanoma patient data from 14 studies via the cBioportal database. Patients were divided into demographic groups and classified according to BRAF, NRAS, KIT and TWT mutation status. Analyses included two-sample Student t -test and two-way analysis of variance tests analysis with Tukey's post hoc test. Survival outcomes were compared via Kaplan-Meier curve and Cox regression. NRAS-mutated patients exhibited decreased overall survival compared to BRAF-mutated patients. Male patients had higher mutation counts across all gene groups than females, with the fewest TWT mutations in comparison to BRAF, NRAS and KIT mutations. Males also exhibited increased mortality risk for NRAS, KIT and TWT mutations compared to BRAF mutations. An unknown primary melanoma was associated with increased mortality risk across all gene groups. NRAS-mutated acral melanoma patients had an increased mortality risk compared to NRAS-mutated cutaneous melanoma patients. Older patients had a higher mortality risk than younger patients. Patients with heavier versus lower weights had lower mortality risk, which was more pronounced for BRAF-mutated patients. These relationships highlight the importance of demographic and pathologic relationships to aid in risk assessment and personalize treatment plans., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The absence of KRAS and NRAS gene mutations (RAS wild type) in metastatic colorectal cancer (mCRC), is associated with a good response to targeted therapy with anti-EGFR receptor antibodies. The current gold standard for RAS mutational status identification is genetic testing on tissue biopsy samples., Objective: This study aimed to assess the relevance of liquid biopsy as a less invasive alternative to tissue biopsy for detecting KRAS/NRAS and BRAF mutations in patients with metastatic colorectal cancer (mCRC). The study also aimed to determine the concordance between liquid biopsy and tissue biopsy., Methods: This is a phase IV, observational, uncontrolled, non-comparative, non-randomized, open label study. RAS/BRAF status will be tested at baseline using tissue and liquid biopsy using the Idylla/Biocartis PCR-based device. The primary endpoint is the comparison of the RAS status based on liquid biopsy with the RAS status based on tissue biopsy., Results: 100 patients with mCRC were included in the study. 75 % of patients showed concordant results between liquid biopsy and tissue biopsy, while 25 % had discordant results. Liquid biopsy demonstrated a sensitivity of 62 % and a specificity of 93 %. The accuracy of liquid biopsy was 75 %, with a moderate agreement between the two tests. The most frequent mutations in concordant cases were in KRAS (41 %), followed by NRAS (4 %) and BRAF (3 %). Mutations were not detected in 42 % of tissue biopsy samples and 60 % of liquid biopsy samples. The presence of hepatic metastases did not significantly affect the concordance between the biopsy methods., Conclusion: Liquid biopsy using the Idylla™ system showed a relatively low sensitivity but high specificity for detecting KRAS/NRAS and BRAF mutations in mCRC patients. Despite some discordant cases, liquid biopsy remains a promising alternative to tissue biopsy due to its non-invasiveness, ability to provide multiple samples, and better representation of tumor heterogeneity., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Hampig Raphael Kourie reports financial support was provided by Merck KGaA, Darmstadt, Germany. Hampig Raphael Kourie reports financial support was provided by Biocartis. Hampig Raphael Kourie reports financial support was provided by Saint-Joseph University of Beirut Research Council. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Masson SAS.)

The major genetic group of Toxoplasma gondii, known as type I, generally displays high lethality in laboratory Mus musculus (mouse) strains, with few exceptions. However, because rodents are the primary reservoir hosts for T. gondii, if this characteristic manifests in the wild, type I strains would be extinct. Therefore, we hypothesized that populations of wild rodents capable of harboring type I T. gondii asymptomatically exist globally and are not limited to a few localized areas, as previously thought. The strength of mouse resistance to T. gondii is known to depend on the affinity of the mouse-expressed immunity-related GTPases B2 (IRGB2) protein for the T. gondii-expressed rphoptry protein 5B (ROP5B) protein. Therefore, the Irgb2 gene sequences of 12 individuals mice captured at two animal farms in Gifu Prefecture, and on an island in Okinawa Prefecture, Japan were determined, and subjected to a molecular phylogenetic analysis together with those of various mouse strains worldwide. The Irgb2 gene of M. musculus individuals captured on one farm and one island showed diverse sequences. The sequences from two individual mice captured in an animal farm formed a single clade with a wild mouse derived CAST/EiJ strain, known for its exceptional resistance to type I T. gondii lethality. These results suggest that M. musuculus individuals resistant to the Type I T. gondii strain may be present in Japan, in addition to the previously known populations in South Asia, Thailand and India.

Purpose: RAS (KRAS/NRAS) mutational status on a tumor biopsy is mandatory to guide the best treatment in metastatic colorectal cancer (mCRC). Determining the RAS mutational status by tumor-tissue biopsy is essential in guiding the optimal treatment decision for mCRC. RAS mutations are negative predictive factors for the use of EGFR monoclonal antibodies. Cell-free DNA (cfDNA) analysis enables minimally invasive monitoring of tumor evolution., Methods/patients: PERSEIDA was an observational, prospective study assessing cfDNA RAS, BRAF and EGFR mutations (using Idylla™) in first-line mCRC, RAS wild-type (baseline tumor-tissue biopsy) patients (cohort 2). Plasma samples were collected before first-line treatment, after 20 ± 2 weeks, and at disease progression., Results: 117 patients were included (103 received panitumumab + chemotherapy as first-line treatment). At baseline, 7 (6.8%) patients had RAS mutations, 4 (3.9%) BRAF mutations and no EGFR mutations were detected (cfDNA, panitumumab + chemotherapy subpopulation [panitumumab + Ch]). The baseline RAS mutational status concordance between tissue and liquid biopsies was 94.0% (93.2%, panitumumab + Ch). At 20 weeks, only one patient in the study (included in the panitumumab + Ch) had an emerging cfDNA RAS mutation. No emerging BRAF or EGFR mutations were reported. At disease progression, 6 patients had emergent mutations not present at baseline (RAS conversion rate: 13.3% [6/45]; 15.0% [6/40], panitumumab + Ch)., Conclusions: The concordance rate between liquid and solid biopsies at baseline was very high, as previously reported, while our results suggest a considerable emergence of RAS mutations during disease progression. Thus, the dynamics of the genomic landscape in ctDNA may provide relevant information for the management of mCRC patients., (© 2024. The Author(s).)

Charcot-Marie-Tooth type 2A (CMT2A) is a single-gene motor sensory neuropathy caused by Mfn2 mutation. It is generally believed that CMT2A involves mitochondrial fusion disruption. However, how Mfn2 mutation mediates the mitochondrial membrane fusion loss and its further pathogenic mechanisms remain unclear. Here, in vivo and in vitro mouse models harboring the Mfn2 R364W , Mfn2 G176S and Mfn2 H165R mutations were constructed. Mitochondrial membrane fusion and fission proteins analysis showed that Mfn2 R364W , Mfn2 G176S , and Mfn2 H165R/+ mutations maintain the expression of Mfn2, but promote Drp1 upregulation and Opa1 hydrolytic cleavage. In Mfn2 H165R/H165R mutation, Mfn2, Drp1, and Opa1 all play a role in inducing mitochondrial fragmentation, and the mitochondrial aggregation is affected by Mfn2 loss. Further research into the pathogenesis of CMT2A showed these three mutations all induce mitochondria-mediated apoptosis, and mitochondrial oxidative phosphorylation damage. Overall, loss of overall fusion activity affects mitochondrial DNA (mtDNA) stability and causes mitochondrial loss and dysfunction, ultimately leading to CMT2A disease. Interestingly, the differences in the pathogenesis of CMT2A between Mfn2 R364W , Mfn2 G176S , Mfn2 H165R/+ and Mfn2 H165R/H165R mutations, including the distribution of Mfn2 and mitochondria, the expression of mitochondrial outer membrane-associated proteins (Bax, VDAC1 and AIF), and the enzyme activity of mitochondrial complex I, are related to the expression of Mfn2., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Melanoma can pose a significant diagnostic challenge due to the high variability in histological morphology and expression of non-melanocytic immunomarkers. We present a case of a 47-year-old male with an aggressive mediastinal neoplasm and disseminated disease posing several diagnostic challenges. Multiple biopsies were submitted from different anatomic locations and during multiple time points showing an undifferentiated round cell tumor (URCT) with synovial sarcoma-like immunophenotype. SS18::SSX fusion was sought through NGS study for diagnostic confirmation. NGS results revealed NRAS and CDKN2A mutations and absence of fusions, resulting in a new review of the histologic material with a broader immunohistochemical panel, finding strong positivity to melanic antibodies. This case is an illustrative example of a malignant melanoma with small round cell morphology showing aberrant expression of CD99, BCL2, TLE1 and SS18-SSX antibodies exposing a potentially hazardous pitfall highlighting the importance of a wide differential diagnosis and the role of confirmational studies with molecular tests., Competing Interests: Declaration of Competing Interest All authors declare that he/she has no potential conflicts of interest., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Background: The dynamics of mitochondrial respiratory cristae (MRC) and its impact on oxidative phosphorylation (OXPHOS) play a crucial role in driving the progression of high-grade glioma (HGG). However, the underlying mechanism remains unclear., Methods: In the present study, we employed machine learning-based transmission electron microscopy analysis of 7141 mitochondria from 54 resected glioma patients. Additionally, we conducted bioinformatics analysis and multiplex immunohistochemical (mIHC) staining of clinical glioma microarrays to identify key molecules involved in glioma. Subsequently, we modulated the expression levels of mitochondrial dynamic-1-like protein (DNM1L/DRP1), and its two receptors, mitochondrial fission protein 1 (FIS1) and mitochondrial fission factor (MFF), via lentiviral transfection to further investigate the central role of these molecules in the dynamics of glioblastoma (GBM) cells and glioma stem cells (GSCs). We then evaluated the potential impact of DNM1L/DRP1, FIS1, and MFF on the proliferation and progression of GBM cells and GSCs using a combination of CCK-8 assay, Transwell assay, Wound Healing assay, tumor spheroid formation assay and cell derived xenograft assay employing NOD/ShiLtJGpt-Prkdc em26Cd52 Il2rg em26Cd22 /Gpt (NCG) mouse model. Subsequently, we validated the ability of the DNM1L/DRP1-FIS1 axis to remodel MRC structure through mitophagy by utilizing Seahorse XF analysis technology, mitochondrial function detection, MRC abundance detection and monitoring dynamic changes in mitophagy., Results: Our findings revealed that compared to low-grade glioma (LGG), HGG exhibited more integrated MRC structures. Further research revealed that DNM1L/DRP1, FIS1, and MFF played pivotal roles in governing mitochondrial fission and remodeling MRC in HGG. The subsequent validation demonstrated that DNM1L/DRP1 exerts a positive regulatory effect on FIS1, whereas the interaction between MFF and FIS1 demonstrates a competitive inhibition relationship. The down-regulation of the DNM1L/DRP1-FIS1 axis significantly impaired mitophagy, thereby hindering the remodeling of MRC and inhibiting OXPHOS function in glioma, ultimately leading to the inhibition of its aggressive progression. In contrast, MFF exerts a contrasting effect on MRC integrity, OXPHOS activity, and glioma progression., Conclusions: This study highlights that the DNM1L/DRP1-FIS1 axis stabilizes MRC structures through mitophagy in HGG cells while driving their OXPHOS activity ultimately leading to robust disease progression. The inhibition of the DNM1L/DRP1-FIS1 axis hinders MRC remodeling and suppresses GBM progression. We propose that down-regulation of the DNM1L/DRP1-FIS1 axis could be a potential therapeutic strategy for treating HGG., (© 2024. The Author(s).)

Mitochondrial form and function are regulated by the opposing forces of mitochondrial dynamics: fission and fusion. Mitochondrial dynamics are highly active and consequential during neuronal ischemia/reperfusion (I/R) injury. Mitochondrial fusion is executed at the mitochondrial inner membrane by Opa1. The balance of long (L-Opa1) and proteolytically cleaved short (S-Opa1) isoforms is critical for efficient fusion. Oma1 is the predominant stress-responsive protease for Opa1 processing. In neuronal cell models, we assessed Oma1 and Opa1 regulation during mitochondrial stress. In an immortalized mouse hippocampal neuron line (HT22), Oma1 was sensitive to mitochondrial membrane potential depolarization (rotenone, FCCP) and hyperpolarization (oligomycin). Further, oxidative stress was sufficient to increase Oma1 activity and necessary for depolarization-induced proteolysis. We generated Oma1 knockout (KO) HT22 cells that displayed normal mitochondrial morphology and fusion capabilities. FCCP-induced mitochondrial fragmentation was exacerbated in Oma1 KO cells. However, Oma1 KO cells were better equipped to perform restorative fusion after fragmentation, presumably due to preserved L-Opa1. We extended our investigations to a combinatorial stress of neuronal oxygen-glucose deprivation and reoxygenation (OGD/R), where we found that Opa1 processing and Oma1 activation were initiated during OGD in an ROS-dependent manner. These findings highlight a novel dependence of Oma1 on oxidative stress in response to depolarization. Further, we demonstrate contrasting fission/fusion roles for Oma1 in the acute response and recovery stages of mitochondrial stress. Collectively, our results add intersectionality and nuance to the previously proposed models of Oma1 activity., (© 2024 The Author(s). The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

In the chloroplast, the 54 kDa subunit of the signal recognition particle (cpSRP54) is involved in the post-translational transport of the light-harvesting chlorophyll a/b-binding proteins (LHCPs) and the co-translational transport of plastid-encoded subunits of the photosynthetic complexes to the thylakoid membrane. It forms a high-affinity complex with plastid-specific cpSRP43 for post-translational transport, while a ribosome-associated pool coordinates its co-translational function. CpSRP54 constitutes a conserved multidomain protein, comprising a GTPase (NG) and a methionine-rich (M) domain linked by a flexible region. It is further characterized by a plastid-specific C-terminal tail region containing the cpSRP43-binding motif. To characterize the physiological role of the various regions of cpSRP54 in thylakoid membrane protein transport, we generated Arabidopsis cpSRP54 knockout (ffc1-2) lines producing truncated cpSRP54 variants or a GTPase point mutation variant. Phenotypic characterization of the complementation lines demonstrated that the C-terminal tail region of cpSRP54 plays an important role exclusively in post-translational LHCP transport. Furthermore, we show that the GTPase activity of cpSRP54 plays an essential role in the transport pathways for both nuclear as well as plastid-encoded proteins. In addition, our data revealed that plants expressing cpSRP54 without the C-terminal region exhibit a strongly increased accumulation of a photosystem I assembly intermediate., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Introduction: Reducing Optic Atrophy 1 (OPA1) expression in skeletal muscle in male mice induces Activation Transcription Factor 4 (ATF4) and the integrated stress response (ISR). Additionally, skeletal muscle secretion of Fibroblast Growth Factor 21 (FGF21) is increased, which mediates metabolic adaptations including resistance to diet-induced obesity (DIO) and glucose intolerance in these mice. Although FGF21 induction in this model can be reversed with pharmacological attenuation of ER stress, it remains to be determined if ATF4 is responsible for FGF21 induction and its metabolic benefits in this model., Methods: We generated mice with homozygous floxed Opa1 and Atf4 alleles and a tamoxifen-inducible Cre transgene controlled by the human skeletal actin promoter to enable simultaneous depletion of OPA1 and ATF4 in skeletal muscle (mAO DKO). Mice were fed high fat (HFD) or control diet and evaluated for ISR activation, body mass, fat mass, glucose tolerance, insulin tolerance and circulating concentrations of FGF21 and growth differentiation factor 15 (GDF15)., Results: In mAO DKO mice, ATF4 induction is absent. Other indices of ISR activation, including XBP1s, ATF6, and CHOP were induced in mAO DKO males, but not in mOPA1 or mAO DKO females. Resistance to diet-induced obesity was not reversed in mAO DKO mice of both sexes. Circulating FGF21 and GDF15 illustrated sexually dimorphic patterns. Loss of OPA1 in skeletal muscle increases circulating FGF21 in mOPA1 males, but not in mOPA1 females. Additional loss of ATF4 decreased circulating FGF21 in mAO DKO male mice, but increased circulating FGF21 in female mAO DKO mice. Conversely, circulating GDF15 was increased in mAO DKO males and mOPA1 females, but not in mAO DKO females., Conclusion: Sex differences exist in the transcriptional outputs of the ISR following OPA deletion in skeletal muscle. Deletion of ATF4 in male and female OPA1 KO mice does not reverse the resistance to DIO. Induction of circulating FGF21 is ATF4 dependent in males, whereas induction of circulating GDF15 is ATF4 dependent in females. Elevated GDF15 in males and FGF21 in females could reflect activation by other transcriptional outputs of the ISR, that maintain mitokine-dependent metabolic protection in an ATF4-independent manner., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Streeter, Persaud, Gao, Manika, Fairman, García-Peña, Marti, Manika, Gaddi, Schickling, Pereira and Abel.)

Acute myeloid leukemia (AML) is an aggressive hematologic neoplasia with a complex polyclonal architecture. Among driver lesions, those involving the FLT3 gene represent the most frequent mutations identified at diagnosis. The development of tyrosine kinase inhibitors (TKIs) has improved the clinical outcomes of FLT3 -mutated patients (Pt). However, overcoming resistance to these drugs remains a challenge. To unravel the molecular mechanisms underlying therapy resistance and clonal selection, we conducted a longitudinal analysis using a single-cell DNA sequencing approach (MissionBioTapestri® platform, San Francisco, CA, USA) in two patients with FLT3-mutated AML. To this end, samples were collected at the time of diagnosis, during TKI therapy, and at relapse or complete remission. For Pt #1, disease resistance was associated with clonal expansion of minor clones, and 2nd line TKI therapy with gilteritinib provided a proliferative advantage to the clones carrying NRAS and KIT mutations, thereby responsible for relapse. In Pt #2, clonal architecture was less complex, and 1st line TKI therapy with midostaurin was able to eradicate the leukemic clones. Our results corroborate previous findings about clonal selection driven by TKIs, highlighting the importance of a deeper characterization of individual clonal architectures for choosing the best treatment plan for personalized approaches aimed at optimizing outcomes.

RUNX1::RUNX1T1 (R::RT1) acute myeloid leukaemia (AML) remains a clinical challenge, and further research is required to model and understand leukaemogenesis. Previous zebrafish R::RT1 models were hampered by embryonic lethality and low penetrance of the malignant phenotype. Here, we overcome this by developing an adult zebrafish model in which the human R::RT1 isoform 9a is co-expressed with the frequently co-occurring oncogenic NRASG12D mutation in haematopoietic stem and progenitor cells (HSPCs), using the Runx1+23 enhancer. Approximately 50% of F0 9a+NRASG12D transgenic zebrafish developed signs of haematological disease between 5 and 14 months, with 27% exhibiting AML-like pathology: myeloid precursor expansion, erythrocyte reduction, kidney marrow hypercellularity and the presence of blasts. Moreover, only 9a+NRASG12D transplant recipients developed leukaemia with high rates of mortality within 40 days, inferring the presence of leukaemia stem cells. These leukaemic features were rare or not observed in animals expressing either the NRAS or 9a oncogenes alone, suggesting 9a and NRAS cooperation drives leukaemogenesis. This novel adult AML zebrafish model provides a powerful new tool for investigating the basis of R::RT1 - NRAS cooperativity with the potential to uncover new therapeutic targets., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Mutations in the PINK1 and PRKN genes are the most frequent genetic cause of early-onset Parkinson disease. The pathogenic p.R275W substitution in PRKN is the most frequent substitution observed in patients, and thus far has been characterized mostly through overexpression models that suggest a possible gain of toxic misfunction. However, its effects under endogenous conditions are largely unknown. We used patient fibroblasts, isogenic neurons, and post-mortem human brain samples from carriers with and without PRKN p.R275W to assess functional impact. Immunoblot analysis and immunofluorescence were used to study mitophagy activation, and mitophagy execution was analyzed by flow cytometry of the reporter mitoKeima. The functional analysis was accompanied by structural investigation of PRKN p.R275W. We observed lower PRKN protein in fibroblasts with compound heterozygous p.R275W mutations. Isogenic neurons showed an allele-dose dependent decrease in PRKN protein. Lower PRKN protein levels were accompanied by diminished phosphorylated ubiquitin and decreased MFN2 modification. Mitochondrial degradation was also allele-dose dependently impaired. Consistently, PRKN protein levels were drastically reduced in human brain samples from p.R275W carriers. Finally, structural simulations showed significant changes in the closed form of PRKN p.R275W. Our data suggest that under endogenous conditions the p.R275W mutation results in a loss-of-function by destabilizing PRKN.

Lidamycin (LDM) has been confirmed to have a strong anti-pancreatic cancer effect and can affect the mitochondrial function of pancreatic cancer cells. Mitofusin-2 (Mfn2) is located in the outer membrane of mitochondria, and Mfn2 is currently believed to play a role in cancer inhibition in pancreatic cancer. In order to explore whether the anti-pancreatic cancer effect of LDM is related to Mfn2-mediated mitophagy, Bioinformatics and in vitro cell experiments are used for experimental research. The experimental results demonstrated that Mfn2 is correlated with mitochondrial autophagy in pancreatic cancer. Lidamycin can increase the expression of Mfn2 in pancreatic cancer and affect the process of EMT, affect the level of reactive oxygen species and mitochondrial membrane potential, and increase the expression of mitochondrial autophagy marker proteins BNIP3L and Beclin1. These results demonstrate that Mfn2 affects mitophagy in pancreatic cancer cells by regulating the expression of Mfn2., (© 2024. The Author(s).)

Background: The interplay between intrauterine and early postnatal environments has been associated with an increased risk of cardiovascular diseases in adulthood, including pulmonary arterial hypertension (PAH). While emerging evidence highlights the crucial role of mitochondrial pathology in PAH, the specific mechanisms driving fetal-originated PAH remain elusive., Methods and Results: To elucidate the role of mitochondrial dynamics in the pathogenesis of fetal-originated PAH, we established a rat model of postnatal catch-up growth following intrauterine growth restriction (IUGR) to induce pulmonary arterial hypertension (PAH). RNA-seq analysis of pulmonary artery samples from the rats revealed dysregulated mitochondrial metabolic genes and pathways associated with increased pulmonary arterial pressure and pulmonary arterial remodeling in the RC group (postnatal catch-up growth following IUGR). In vitro experiments using pulmonary arterial smooth muscle cells (PASMCs) from the RC group demonstrated elevated proliferation, migration, and impaired mitochondrial functions. Notably, reduced expression of Mitofusion 2 (Mfn2), a mitochondrial outer membrane protein involved in mitochondrial fusion, was observed in the RC group. Reconstitution of Mfn2 resulted in enhanced mitochondrial fusion and improved mitochondrial functions in PASMCs of RC group, effectively reversing the Warburg effect. Importantly, Mfn2 reconstitution alleviated the PAH phenotype in the RC group rats., Conclusions: Imbalanced mitochondrial dynamics, characterized by reduced Mfn2 expression, plays a critical role in the development of fetal-originated PAH following postnatal catch-up growth after IUGR. Mfn2 emerges as a promising therapeutic strategy for managing IUGR-catch-up growth induced PAH., (© 2024. The Author(s).)

RAS p.Q61R is the most prevalent hot-spot mutation in RAS and RAS-like mutated thyroid nodules. A few studies evaluated RAS p.Q61R by immunohistochemistry (RASQ61R-IHC). We performed a retrospective study of an institutional cohort of 150 patients with 217 thyroid lesions tested for RASQ61R-IHC, including clinical, cytologic and molecular data. RASQ61R-IHC was performed on 217 nodules (18% positive, 80% negative, and 2% equivocal). RAS p.Q61R was identified in 76% (n = 42), followed by RAS p.Q61K (15%; n = 8), and RAS p.G13R (5%; n = 3). NRAS p.Q61R isoform was the most common (44%; n = 15), followed by NRAS p.Q61K (17%; n = 6), KRAS p.Q61R (12%; n = 4), HRAS p.Q61R (12%; n = 4), HRAS p.Q61K (6%; n = 2), HRAS p.G13R (6%; n = 2), and NRAS p.G13R (3%; n = 1). RASQ61R-IHC was positive in 47% of noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP; 17/36), 22% of follicular thyroid carcinomas (FTC; 5/23), 10% of follicular thyroid adenomas (FTA; 4/40), and 8% of papillary thyroid carcinomas (PTC; 9/112). Of PTC studied (n = 112), invasive encapsulated follicular variant (IEFVPTC; n = 16) was the only subtype with positive RASQ61R-IHC (56%; 9/16). Overall, 31% of RAS-mutated nodules were carcinomas (17/54); and of the carcinomas, 94% (16/17) were low-risk per American Thyroid Associated (ATA) criteria, with only a single case (6%; 1/17) considered ATA high-risk. No RAS-mutated tumors recurred, and none showed local or distant metastasis (with a follow-up of 0-10 months). We found that most RAS-mutated tumors are low-grade neoplasms. RASQ61R-IHC is a quick, cost-effective, and reliable way to detect RAS p.Q61R in follicular-patterned thyroid neoplasia and, when malignant, guide surveillance., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background/aim: Despite therapeutic advancements, metastatic colorectal cancer is usually fatal, necessitating novel approaches based on the molecular pathogenesis to improve outcomes. Some colorectal cancers have no mutations in the extended RAS panel (KRAS, NRAS, BRAF) genes and represent a special subset, which deserves particular therapeutic considerations., Materials and Methods: The genomic landscape of colorectal cancers from publicly available genomic series was interrogated, using the cBioportal platform. Colorectal cancer cohorts with cancers devoid of KRAS/NRAS or BRAF mutations were evaluated for the presence of mutations in the catalytic sub-unit alpha of kinase PI3K, encoded by the gene PIK3CA., Results: PIK3CA mutations in the absence of KRAS/NRAS/BRAF mutations were observed in 3.7% to 7.6% of colorectal cancers in the different series examined. Patients with all four genes in wildtype configuration (quadruple wild type) represented 32.2% to 39.9% of cases in the different series examined. Compared with quadruple wild type cancers, triple (KRAS/NRAS/BRAF) wild type/PIK3CA mutated cancers had a higher prevalence of high TMB cases and additional mutations in colorectal cancer associated genes except for mutations in TP53. Mutations in genes encoding for epigenetic modifiers and the DNA damage response (DDR) were also more frequent in triple wild type/PIK3CA mutated cancers. The prognosis of the two groups was comparable., Conclusion: Colorectal cancers with PIK3CA mutations in the absence of KRAS/NRAS/BRAF mutations have frequently mutations in epigenetic modifiers and DDR response genes, which may provide opportunities for targeting. These mutations are present in a smaller subset of quadruple wild type cancers., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Giant congenital melanocytic nevi (GCMN) can be cosmetically significant and can lead to melanoma. There is no standard pharmacologic treatment for GCMN. We present the case of an 8-year-old female with kaposiform lymphangiomatosis caused by an NRAS mutation whose nevus spilus-type GCMN improved on oral selumetinib., (© 2024 The Author(s). Pediatric Dermatology published by Wiley Periodicals LLC.)

Background: Patients with colorectal cancer can benefit from anti-EGFR (epidermal growth factor receptor) therapy. However, this therapy is not effective for treating colorectal cancers with constitutive activating mutations in the KRAS, NRAS, and BRAF genes. Molecular analysis of tumor tissue frequently informs treatment decisions for colorectal cancer. This study aims to identify KRAS, NRAS, and BRAF mutations in Iranian patients diagnosed with colorectal cancer and to assess the prevalence of these mutations relative to the tumor differentiation stage within these populations., Methods: From April 2018 to December 2022, 2000 specimens from patients with colorectal cancer were collected. Data on sex, age, and tumor differentiation stage were recorded for all samples. For mutation detection, the KRAS and NRAS exons (2, 3, and 4) were amplified using the Diatech kit, and a specific primer was used to amplify BRAF exon 15. Pyrosequencing was then performed., Results: Analysis of samples revealed that 1105 specimens (55.3%) contained mutations in at least one of the screened genes. Among the genes studied, the highest occurrence was the KRAS mutation at 47.4%, followed by NRAS at 5.3% and BRAF at 2.7%. Most KRAS mutations were found in exon 2 (89.7%), with the G12D mutation being the most prevalent at 32% of cases. There was a significant difference in the rate of KRAS mutations in women (52.5%) compared to men (43.5%) (P =  0.02). For NRAS, the majority mutations were observed in exon 3 (76.2%), with the Q61H mutation being the most prevalent at 28.5% of cases. There were no significant associations between the clinicopathological parameters and mutations., Conclusion: The study's findings indicate a rising frequency of mutations in these genes in Iran, highlighting the need to screening mutations in the main exons of all three genes for effective colorectal cancer treatment strategies., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Interferon-alpha (IFNα) is a common treatment for chronic hepatitis B virus (HBV) infection, but its efficacy varies widely among patients. GTPASE, an interferon-stimulated gene (ISG), has recently been identified as a factor in antiviral immunity, though its role in HBV infection is not fully understood., Objective: This study investigates the role of GTPASE in enhancing the antiviral effects of IFNα against HBV and elucidates its mechanism of action., Methods: We analyzed the impact of GTPASE overexpression and silencing on HBV replication and clearance in HBV-infected cells. Molecular docking studies assessed the interaction between GTPASE and HBV surface antigens (HBs). Clinical samples from HBV patients undergoing Peg-IFNα treatment were also evaluated for GTPASE expression and its correlation with treatment efficacy., Results: Overexpression of GTPASE led to significant inhibition of HBV replication, increased HBeAg seroconversion, and enhanced HBsAg clearance. GTPASE directly bound to HBs proteins, reducing their levels and affecting viral particle formation. Silencing GTPASE reduced these effects, while combined treatment with Peg-IFNα and GTPASE overexpression further improved antiviral outcomes. Mutational analysis revealed that specific sites in GTPASE are crucial for its antiviral activity., Conclusions: GTPASE acts as a positive regulator in IFNα-induced antiviral immunity against HBV. It enhances the therapeutic efficacy of IFNα by targeting HBs and modulating viral replication. GTPASE levels may serve as a predictive biomarker for response to Peg-IFNα therapy, highlighting its potential for improving individualized treatment strategies for chronic HBV infection., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The arrest of neural crest-derived sympathoadrenal neuroblast differentiation contributes to neuroblastoma formation, and overriding this blocked differentiation is a clear strategy for treating high-risk neuroblastoma. A better understanding of neuroblast or neuroblastoma differentiation is essential for developing new therapeutic approaches. It has been proposed that Krueppel-like factor 7 (KLF7) is a neuroblastoma super-enhancer-associated transcription factor gene. Moreover, KLF7 was found to be intensely active in postmitotic neuroblasts of the developing nervous system during embryogenesis. However, the role of KLF7 in the differentiation of neuroblast or neuroblastoma is unknown. Here, we find a strong association between high KLF7 expression and favorable clinical outcomes in neuroblastoma. KLF7 induces differentiation of neuroblastoma cells independently of the retinoic acid (RA) pathway and acts cooperatively with RA to induce neuroblastoma differentiation. KLF7 alters the GTPase activity and multiple differentiation-related genes by binding directly to the promoters of neuroblast differentiation-associated protein (AHNAK and AHNAK2) and glycerophosphodiester phosphodiesterase domain-containing protein 5 (GDPD5) and regulating their expression. Furthermore, we also observe that silencing KLF7 in neuroblastoma cells promotes the adrenergic-to-mesenchymal transition accompanied by changes in enhancer-mediated gene expression. Our results reveal that KLF7 is an inducer of neuroblast or neuroblastoma differentiation with prognostic significance and potential therapeutic value., (© 2024 Federation of European Biochemical Societies.)

Keratin intermediate filaments form dynamic filamentous networks, which provide mechanical stability, scaffolding, and protection against stress to epithelial cells. Keratins and other intermediate filaments have been increasingly linked to the regulation of mitochondrial function and homeostasis in different tissues and cell types. While deletion of keratin 8 (K8 -/- ) in mouse colon elicits a colitis-like phenotype, epithelial hyperproliferation, and blunted mitochondrial ketogenesis, the role of K8 in colonocyte mitochondrial function and energy metabolism is unknown. We used two K8 knockout mouse models and CRISPR/Cas9 K8 -/- colorectal adenocarcinoma Caco-2 cells to answer this question. The results show that K8 -/- colonocyte mitochondria in vivo are smaller and rounder and that mitochondrial motility is increased in K8 -/- Caco-2 cells. Furthermore, K8 -/- Caco-2 cells displayed diminished mitochondrial respiration and decreased mitochondrial membrane potential compared with controls, whereas glycolysis was not affected. The levels of mitochondrial respiratory chain complex proteins and mitochondrial regulatory proteins mitofusin-2 and prohibitin were decreased both in vitro in K8 -/- Caco-2 cells and in vivo in K8 -/- mouse colonocytes, and reexpression of K8 into K8 -/- Caco-2 cells normalizes the mitofusin-2 levels. Mitochondrial Ca 2+ is an important regulator of mitochondrial energy metabolism and homeostasis, and Caco-2 cells lacking K8 displayed decreased levels and altered dynamics of mitochondrial matrix and cytoplasmic Ca 2+ . In summary, these novel findings attribute an important role for colonocyte K8 in stabilizing mitochondrial shape and movement and maintaining mitochondrial respiration and Ca 2+ signaling. Further, how these metabolically compromised colonocytes are capable of hyperproliferating presents an intriguing question for future studies. NEW & NOTEWORTHY In this study, we show that colonocyte intermediate filament protein keratin 8 is important for stabilizing mitochondria and maintaining mitochondrial energy metabolism, as keratin 8-deficient colonocytes display smaller, rounder, and more motile mitochondria, diminished mitochondrial respiration, and altered Ca 2+ dynamics. Changes in fusion-regulating proteins are rescued with reexpression of keratin 8. These alterations in colonocyte mitochondrial homeostasis contribute to keratin 8-associated colitis pathophysiology.

Background: Mutations in KRAS and NRAS are associated with a lack of response to cetuximab and panitumumab, two biologics used for third-line therapy of metastatic colorectal cancer (mCRC). In British Columbia, Canada, eligibility for cetuximab or panitumumab was first based on single-gene KRAS testing. OncoPanel, a multi-gene next-generation sequencing panel with both KRAS and NRAS, was introduced in 2016. Our objective was to estimate the real-world cost-effectiveness of OncoPanel versus to single-gene KRAS testing to inform eligibility for cetuximab or panitumumab in mCRC., Methods: Using population-based administrative health data, we identified a cohort of mCRC patients who had received a KRAS or OncoPanel test, and completed prior chemotherapy in 2010-2019. We matched KRAS- and OncoPanel-tested patients (1:1) using genetic matching to balance baseline covariates. Mean and incremental 3-year costs, survival, and quality-adjusted survival were estimated using inverse-probability-of-censoring weighting and bootstrapping. We conducted scenario-based sensitivity analysis for key costs and assumptions., Findings: All OncoPanel-tested cases (n=371) were matched to a KRAS-tested comparator. In the KRAS and OncoPanel groups, respectively, 55·8 % and 41·2 % of patients were potentially eligible for cetuximab or panitumumab based on mutation status. Incremental cost and effectiveness of OncoPanel were $72 (95 % CI: -6387, 6107), -0·004 life-years (95 % CI: -0·119, 0·113), and -0·011 quality-adjusted life-years (95 % CI: -0·094, 0·075). Reductions in systemic therapy costs were offset by increased costs in other resources. Results were moderately sensitive to time horizon and changes in testing or treatment cost., Interpretation: The use of OncoPanel resulted in more precise targeting of cetuximab and panitumumab, but there was no change in incremental cost or quality-adjusted survival. Understanding the balance of costs achieved in practice can provide insight into the effect of future changes in testing policy, test cost, treatment eligibility, or drug prices in this setting., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. DAR’s institution has received research funding for a project from Roche Canada and DAR has received travel funding from Illumina. DW co-directs IMPRINT Research Consulting, has consulted for Birota Economics Group and AstraZeneca Canada, and has received travel funding from Illumina. SY has served on Data Safety Monitoring or Advisory Boards for Amgen, AstraZeneca, Bayer, Janssen, Pfizer, Roche, Servier. REP, MS, SB, SP and IB declare that they have no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)