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Sphingosine 1-phosphate receptor 1 (S1PR1) is a G protein-coupled receptor essential for vascular development and postnatal vascular homeostasis. When exposed to sphingosine 1-phosphate (S1P) in the blood of ∼1 μM, S1PR1 in endothelial cells retains cell-surface localization, while lymphocyte S1PR1 shows almost complete internalization, suggesting the cell-surface retention of S1PR1 is endothelial cell specific. To identify regulating factors that function to retain S1PR1 on the endothelial cell surface, here we utilized an enzyme-catalyzed proximity labeling technique followed by proteomic analyses. We identified Filamin B (FLNB), an actin-binding protein involved in F-actin cross-linking, as a candidate regulating protein. We show FLNB knockdown by RNA interference induced massive internalization of S1PR1 into early endosomes, which was partially ligand dependent and required receptor phosphorylation. Further investigation showed FLNB was also important for the recycling of internalized S1PR1 back to the cell surface. FLNB knockdown did not affect the localization of S1PR3, another S1P receptor subtype expressed in endothelial cells, nor did it affect localization of ectopically expressed β2-adrenergic receptor. Functionally, we show FLNB knockdown in endothelial cells impaired S1P-induced intracellular phosphorylation events and directed cell migration and enhancement of the vascular barrier. Taken together, our results demonstrate that FLNB is a novel regulator critical for S1PR1 cell-surface localization and thereby proper endothelial cell function., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Variants of filamin C (FLNC) have been identified as rare genetic substrate for hypertrophic cardiomyopathy (HCM). Data on the clinical course of FLNC-related HCM are conflicting with some studies suggesting mild phenotypes whereas other studies have reported more severe outcomes. In this study, we present a novel FLNC variant (Ile1937Asn) that was identified in a large family of French-Canadian descent with excellent segregation data. FLNC-Ile1937Asn is a novel missense variant characterized by full penetrance and poor clinical outcomes. End stage heart failure requiring transplantation occurred in 43% and sudden cardiac death in 29% of affected family members. Other particular features of FLNC-Ile1937Asn include an early disease onset (mean age of 19 years) and the development of a marked atrial myopathy (severe biatrial dilatation with remodeling and multiple complex atrial arrhythmias) that was present in all gene carriers. The FLNC-Ile1937Asn variant is a novel, pathogenic mutation resulting in a severe form of HCM with full disease penetrance. The variant is associated with a high proportion of end-stage heart failure, heart transplantation, and disease-related mortality. Close follow-up and appropriate risk stratification of affected individuals at specialized heart centers is recommended., (© 2023 The Authors. American Journal of Medical Genetics Part A published by Wiley Periodicals LLC.)

Objective: To explore the clinical and genetic characteristics of a fetus with Melnick-Needles syndrome (MNS)., Methods: A fetus with MNS diagnosed at Ningbo Women and Children's Hospital in November 2020 was selected as the study subject. Clinical data was collected. Pathogenic variant was screened by using trio-whole exome sequencing (trio-WES). Candidate variant was verified by Sanger sequencing., Results: Prenatal ultrasonography of the fetus had shown multiple anomalies including intrauterine growth retardation, bilateral femur curvature, omphalocele, single umbilical artery, and oligohydramnios. Trio-WES revealed that the fetus has harbored hemizygous c.3562G>A (p.A1188T) missense variant of the FLNA gene. Sanger sequencing confirmed that the variant was maternally derived, whilst its father was of a wild type. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was predicted to be likely pathogenic (PS4+PM2_Supporting+PP3+PP4)., Conclusion: The hemizygous c.3562G>A (p.A1188T) variant of the FLNA gene probably underlay the structural abnormalities in this fetus. Genetic testing can facilitate accurate diagnosis of MNS and provide a basis for genetic counseling for this family.

Myofibrillar myopathies (MFM) are a group of chronic muscle diseases pathophysiologically characterized by accumulation of protein aggregates and structural failure of muscle fibers. A subtype of MFM is caused by heterozygous mutations in the filamin C ( FLNC ) gene, exhibiting progressive muscle weakness, muscle structural alterations and intracellular protein accumulations. Here, we characterize in depth the pathogenicity of two novel truncating FLNc variants (p.Q1662X and p.Y2704X) and assess their distinct effect on FLNc stability and distribution as well as their impact on protein quality system (PQS) pathways. Both variants cause a slowly progressive myopathy with disease onset in adulthood, chronic myopathic alterations in muscle biopsy including the presence of intracellular protein aggregates. Our analyses revealed that p.Q1662X results in FLNc haploinsufficiency and p.Y2704X in a dominant-negative FLNc accumulation. Moreover, both protein-truncating variants cause different PQS alterations: p.Q1662X leads to an increase in expression of several genes involved in the ubiquitin-proteasome system (UPS) and the chaperone-assisted selective autophagy (CASA) system, whereas p.Y2704X results in increased abundance of proteins involved in UPS activation and autophagic buildup. We conclude that truncating FLNC variants might have different pathogenetic consequences and impair PQS function by diverse mechanisms and to varying extents. Further studies on a larger number of patients are necessary to confirm our observations.

Aims: Degenerative mitral valve dystrophy (MVD) leading to mitral valve prolapse is the most frequent form of MV disease, and there is currently no pharmacological treatment available. The limited understanding of the pathophysiological mechanisms leading to MVD limits our ability to identify therapeutic targets. This study aimed to reveal the main pathophysiological pathways involved in MVD via the multimodality imaging and transcriptomic analysis of the new and unique knock-in (KI) rat model for the FilaminA-P637Q (FlnA-P637Q) mutation associated-MVD., Methods and Results: Wild-type (WT) and KI rats were evaluated morphologically, functionally, and histologically between 3-week-old and 3-to-6-month-old based on Doppler echocardiography, 3D micro-computed tomography (microCT), and standard histology. RNA-sequencing and Assay for Transposase-Accessible Chromatin (ATAC-seq) were performed on 3-week-old WT and KI mitral valves and valvular cells, respectively, to highlight the main signalling pathways associated with MVD. Echocardiographic exploration confirmed MV elongation (2.0 ± 0.1 mm vs. 1.8 ± 0.1, P = 0.001), as well as MV thickening and prolapse in KI animals compared to WT at 3 weeks. 3D MV volume quantified by microCT was significantly increased in KI animals (+58% vs. WT, P = 0.02). Histological analyses revealed a myxomatous remodelling in KI MV characterized by proteoglycans accumulation. A persistent phenotype was observed in adult KI rats. Signalling pathways related to extracellular matrix homeostasis, response to molecular stress, epithelial cell migration, endothelial to mesenchymal transition, chemotaxis and immune cell migration, were identified based on RNA-seq analysis. ATAC-seq analysis points to the critical role of transforming growth factor-β and inflammation in the disease., Conclusion: The KI FlnA-P637Q rat model mimics human myxomatous MVD, offering a unique opportunity to decipher pathophysiological mechanisms related to this disease. Extracellular matrix organization, epithelial cell migration, response to mechanical stress, and a central contribution of immune cells are highlighted as the main signalling pathways leading to myxomatous MVD. Our findings pave the road to decipher underlying molecular mechanisms and the specific role of distinct cell populations in this context., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Introduction and Objectives: Missense mutations in the filamin C (FLNC) gene have been reported as cause of inherited cardiomyopathy. Knowledge of the pathogenicity and genotype-phenotype correlation remains scarce. Our aim was to describe a distinctive cardiac phenotype related to rare missense FLNC variants in the ROD2 domain., Methods: We recruited 21 unrelated families genetically evaluated because of hypertrophic cardiomyopathy (HCM)/restrictive cardiomyopathy (RCM) phenotype carrying rare missense variants in the ROD2 domain of FLNC (FLNC-mRod2). Carriers underwent advanced cardiac imaging and genetic cascade screening. Myocardial tissue from 3 explanted hearts of a missense FLNC carrier was histologically analyzed and compared with an FLNC-truncating variant heart sample and a healthy control. Plasmids independently containing 3 FLNC missense variants were transfected and analyzed using confocal microscopy., Results: Eleven families (52%) with 20 assessed individuals (37 [23.7-52.7]) years showed 15 cases with a cardiac phenotype consisting of an overlap of HCM-RCM and left ventricular hypertrabeculation (saw-tooth appearance). During a median follow-up of 6.49 years, they presented with advanced heart failure: 16 (80%) diastolic dysfunction, 3 heart transplants, 3 heart failure deaths) and absence of cardiac conduction disturbances or skeletal myopathy. A total of 6 families had moderate genotype-phenotype segregation, and the remaining were de novo variants. Differential extracellular matrix remodeling and FLNC distribution among cardiomyocytes were confirmed on histology. HT1080 and H9c2 cells did not reveal cytoplasmic aggregation of mutant FLNC., Conclusions: FLNC-mRod2 variants show a high prevalence of an overlapped phenotype comprising RCM, HCM and deep hypertrabeculation with saw-tooth appearance and distinctive cardiac histopathological remodeling., (Copyright © 2022 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.)

Background: Filamin A, encoded by the X-linked gene FLNA, links the cell membrane with the cytoskeleton and acts as a regulator of the actin cytoskeleton. Mutations in FLNA cause a large spectrum of congenital malformations during embryonic development, including Melnick-Needles syndrome (MNS). However, reports of MNS, especially in males, are rare, and the pathogenesis molecular mechanisms are not well understood., Methods: We found a family with two consecutive miscarriages of similar fetuses with multiple malformations. DNA was extracted from peripheral blood and tissues, and whole exome sequencing was performed for genetic analysis. Then, we created a C57BL/6 mouse with a point mutation by CRISPR/Cas-mediated genome engineering. The migration of primary abdominal muscle cell was detected by wound healing assay., Results: The first fetus showed congenital hygroma colli and omphalocele identified by ultrasound at 12 wks; the second fetus showed hygroma colli and thoraco abdominoschisis at 12 wks, with a new hemizygous mutation c.4420G>A in exon 26 of the FLNA gene, which is predicted to cause an amino acid substitution (p.Asp1474Asn). The mother and grandmother were both present in the c.4420G>A heterozygous state, and the mother's healthy brother had wild-type FLNA. These FLNA-mutated mice exhibited a broader central gap between the rectus abdominis than the wild type (WT), similar to the midline structure dysplasia of the abdominal wall in the two fetuses. Wound healing assays showed the attenuated migration capacity of abdominal muscle cells in mice with mutated FLNA. Finally, we summarized the cases of MNS with FLNA mutation from the accessible published literature thus far., Conclusion: Our research revealed a mutation site of the FLNA for MNS and explored the mechanism of midline structure dysplasia in the abdominal wall of male patients, which could provide more evidence for the clinical diagnosis and genetic counseling of families with these disorders., (© 2023 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

Non-alcoholic steatohepatitis (NASH) is a chronic and progressive liver disease characterized by steatosis, inflammation, and fibrosis. Filamin A (FLNA), an actin-binding protein, is involved in various cell functions, including the regulation of immune cells and fibroblasts. However, its role in the development of NASH through inflammation and fibrogenesis is not fully understood. In this study, we found that FLNA expression was increased in liver tissues of patients with cirrhosis and mice with non-alcoholic fatty liver disease (NAFLD)/NASH and fibrosis. Immunofluorescence analysis showed that FLNA was primarily expressed in macrophages and hepatic stellate cells (HSCs). Knocking down of FLNA by specific shRNA in phorbol-12-myristate-13-acetate (PMA)-derived THP-1 macrophages reduced lipopolysaccharide (LPS)-stimulated inflammatory response. The decreased mRNA levels of inflammatory cytokines and chemokines and suppression of the STAT3 signaling were observed in FLNA-downregulated macrophages. In addition, knockdown of FLNA in immortalized human hepatic stellate cells (LX-2 cells) resulted in decreased mRNA levels of fibrotic cytokines and enzymes involved in collagen synthesis, as well as increased levels of metalloproteinases and pro-apoptotic proteins. Overall, these results suggest that FLNA may contribute to the pathogenesis of NASH through its role in the regulation of inflammatory and fibrotic mediators., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Filamin A (FLNA) cross-links actin filaments and mediates mechanotransduction by force-induced conformational changes of its domains. FLNA's mechanosensitive immunoglobulin-like repeats (R) interact with each other to create cryptic binding sites, which can be exposed by physiologically relevant mechanical forces. Using the FLNA mechanosensing domains as an affinity ligand followed by stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics, we recently identified smoothelin and fimbacin as FLNA mechanobinding proteins. Here, using the mechanosensing domain as an affinity ligand and two labeled amino acids, we identify salvador homologue 1 (SAV1), a component of the Hippo pathway kinase cascade, as a new FLNA mechanobinding partner. We demonstrate that SAV1 specifically interacts with the cryptic C-D cleft of FLNA R21 and map the FLNA-binding site on SAV1. We show that point mutations on the R21 C strand block the SAV1 interaction and find that SAV1 contains a FLNA-binding motif in the central region ( 116 Phe- 124 Val). Point mutations F116A and T118A (FT/AA) disrupt the interaction. A proximity ligation assay reveals that their interaction occurs in the cytosol in an actin polymerization-dependent manner. Although SAV1 is typically found in the cytosol, disrupting the interaction between SAV1 and FLNA causes SAV1 to diffuse to the nucleus and YAP1 to diffuse to the cytosol in an inverse relationship. These results suggest that FLNA mediates regulation of the Hippo pathway through actin polymerization-dependent interaction with SAV1.

Filamin A (FLNA) is a high molecular weight cytoskeleton protein important for cell locomotion. A relationship between FLNA mutations and pulmonary arterial hypertension (PAH) has previously been reported; however, the detailed mechanism remains unclear. The present study aimed to explore the role of FLNA in vascular smooth muscle cells during the development of PAH. Smooth muscle cell (SMC)‑specific FLNA‑deficient mice were generated and the mice were then exposed to hypoxia for 28 days to build the mouse model of PAH. Human pulmonary arterial smooth muscle cells (PASMCs) were also cultured and transfected with FLNA small interfering RNA or overexpression plasmids to investigate the effects of FLNA on PASMC proliferation and migration. Notably, compared with control individuals, the expression levels of FLNA were increased in lung tissues from patients with PAH, and it was obviously expressed in the PASMCs of pulmonary arterioles. FLNA deficiency in SMCs attenuated hypoxia‑induced pulmonary hypertension and pulmonary vascular remodeling. In vitro studies suggested that absence of FLNA impaired PASMC proliferation and migration, and produced lower levels of phosphorylated (p)‑PAK‑1 and RAC1 activity. However, FLNA overexpression promoted PASMC proliferation and migration, and increased the expression levels of p‑PAK‑1 and RAC1 activity. The present study highlights the role of FLNA in pulmonary vascular remodeling; therefore, it could serve as a potential target for the treatment of PAH.

Objective: The purpose of our work was to explore the association of mutations in the androgen receptor gene and copy numbers of the androgen-receptor silk protein A complex with glutathione-S-transferases T1 and M1 in prostate cancer patients., Materials and Methods: Eighty-five patients with PC and 85 healthy controls were included in the study. Fasting peripheral venous blood was collected, whole blood genomic DNA was extracted, and AR gene-receptor genotype was detected by a high-resolution melting curve analysis detection technology. Expression levels of androgen receptor (AR) and filamin protein A (FlnA) were detected by Western blotting. RT-PCR was used to detect the copy number of T1 and M1 glutathione-S-transferases., Results: The wild-type androgen receptor gene rs5918762 is of TT type. The frequencies of CC and TC genes in the prostate cancer group were significantly higher than those in the normal control group ( P < 0.05). Compared with TT-type PC patients, PC patients with TC-type and CC-type had higher expression levels of sex hormone receptor silk protein A complex and higher copy numbers of GSTT1 and GSTM1 ( P < 0.05). Androgen-receptor gene mutation (T ⟶ C) was significantly positively correlated with the expression level of androgen-receptor silk protein A complex and the copy number of GSTT1 and GSTM1., Conclusion: Androgen-receptor gene polymorphisms were significantly associated with expression levels of androgen receptor complex A and silk proteins, and copy numbers of T1 and M1 glutathione-S-transferases. A combination of four factors can be used to identify prostate cancer susceptibility and disease progression., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Yan Zhang et al.)

Background: The differential diagnosis of intrahepatic cholangiocarcinomas (iCCAs) from metastatic adenocarcinomas from organs adjacent to the liver (gallbladder, pancreas, and stomach) is difficult due to histopathological similarity and a lack of specific markers. This study aimed to develop a method to differentiate iCCA and adenocarcinomas originated from extrahepatic organs adjacent to the liver., Methods: We retrospectively enrolled surgically resected iCCA (n = 181) and adenocarcinomas from extrahepatic organs (n = 30, n = 28, and n = 38 from gallbladder, pancreas, and stomach, respectively) between 2007 and 2013. The albumin mRNA in situ hybridization (ISH) and immunohistochemistry (IHC) of filamin-A and cytokeratin 19 (CK19) were performed using tissue microarray. Using logistic regression analysis of three markers, iCCA-score was developed, and its diagnostic performance was evaluated., Results: The iCCAs were more frequently positive for albumin ISH (23.2% vs. 0%), filamin-A IHC (47.5% vs. 12.5%) and CK19 (68.5% vs. 40.6%) than extrahepatic adenocarcinomas (p < 0.001 for all). The iCCA-score consisting of these three markers was developed, and it showed higher diagnostic performance (area under the curve [AUC], 0.798 vs. 0.616, p < 0.001). Taking an iCCA-score of 2 or higher as the threshold for iCCA, the sensitivity was substantially higher than albumin ISH alone (45.9% and 23.2%, respectively; p < 0.001), but maintained high specificity (94.8% and 100%, respectively)., Conclusion: Albumin ISH and IHC staining for filamin-A and CK19 showed distinct expression patterns between iCCA and extrahepatic adenocarcinomas from gallbladder, pancreas, and stomach. We developed iCCA-score that consisted of those three markers, and it showed better diagnostic performance than albumin ISH alone., (© 2022. Asian Pacific Association for the Study of the Liver.)

FLNC, encoding filamin C, is one of the most mutated genes in dilated and hypertrophic cardiomyopathy. However, the precise role of filamin C in mammalian heart remains unclear. In this study, we demonstrated Flnc global (FlncgKO) and cardiomyocyte-specific knockout (FlnccKO) mice died in utero from severely ruptured ventricular myocardium, indicating filamin C is required to maintain the structural integrity of myocardium in the mammalian heart. Contrary to the common belief that filamin C acts as an integrin inactivator, we observed attenuated activation of β1 integrin specifically in the myocardium of FlncgKO mice. Although deleting β1 integrin from cardiomyocytes did not recapitulate the heart rupture phenotype in Flnc knockout mice, deleting both β1 integrin and filamin C from cardiomyocytes resulted in much more severe heart ruptures than deleting filamin C alone. Our results demonstrated that filamin C works in concert with β1 integrin to maintain the structural integrity of myocardium during mammalian heart development., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: JC consults for Lexeo Therapeutic., (Copyright: © 2023 Wu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Introduction: In view of the vital implication of long noncoding RNAs in tumorigenesis, we possess the aim to determine the action effects and mechanisms of LINC01002 in prostate cancer (PCa)., Methods: Expression level of LINC01002, miR-650, or filamin A (FLNA) in PCa tissues and cells was assessed using quantitative real-time PCR or Western blotting. Cell proliferative and migratory capacities were investigated by Cell Counting Kit-8 (CCK-8) and wound healing assays. Cell apoptosis was investigated by the levels of Bax and Bcl-2. Xenograft models were constructed to testify the role of LINC01002 in vivo. The anticipated binding of miR-650 to LINC01002 or FLNA was confirmed by dual-luciferase reporter or RNA binding protein immunoprecipitation assays., Results: Relatively poor expression of LINC01002 and FLNA, and high expression of miR-650 were identified in PCa tumor specimens and cells. Ectopic LINC01002 expression restrained PCa cell proliferation/migration and provoked apoptosis in vitro, and blocked solid tumor growth in Xenograft models. MiR-650 was directly targeted by LINC01002, and it also directly bound to FLNA. MiR-650 reintroduction in PCa cells overexpressing LINC01002 or FLNA partly reversed the anticancer effects of LINC01002 or FLNA overexpression, thus recovering PCa cell proliferation/migration and repressing apoptosis., Conclusion: LINC01002 deregulation was linked to PCa development. LINC01002 exerted potential anticancer effects in PCa via targeting the miR-650/FLNA pathway, which, at least in part, provided a basis for the involvement of LINC01002 as a therapeutic target in PCa., (© 2023 S. Karger AG, Basel.)

The loss of function (LOF) due to mutations in the Filamin A (FLNA) gene may result in abnormality of the FLNA protein. Of the many clinical syndromes, this condition may produce chronic lung disease, which usually presents and is diagnosed in the infant/toddler age group. Its clinical pattern may mimic broncho-pulmonary dysplasia. It is part of the entities included in childhood interstitial lung disease group of disorders. We are herein reporting a patient that was diagnosed with FLNA-associated lung disease at 11 years of age. This case provides a unique insight into the long-term course of lung disease in this illness and broadens our understanding of the spectrum of its presentation. Although the patient had symptoms early in life, the diagnosis was not entertained because of the rarity of the disorder, its atypical and clinically mild presentation, and discontinuous care due to parents moving to different cities for employment reasons. Her presentation to our institution was for pneumonia. Due to highly unusual chest X-ray images, asthenia, and early clubbing, an extensive workup included further imaging and a lung biopsy. The final diagnosis was confirmed by the detection of FLNA LOF gene mutation., (© 2022 Wiley Periodicals LLC.)

The nucleocytoplasmic translocation of yes-associated protein 1 (YAP1) controls the growth of animal tissues and organs. YAP1 binds to transcription factors in the nucleus to activate the transcription of proliferation and anti-apoptotic genes. The Hippo pathway prevents the nuclear translocation of YAP1 by phosphorylating YAP1, while mechanical forces promote it by opening the nuclear pore complex and stimulating other signaling pathways. Recently we found that Protein salvador homolog 1 (SAV1), a component of the Hippo pathway, interacts with filamin A (FLNA) in a force-dependent manner, raising a possibility that the Hippo pathway is regulated by mechanical force through the FLNA-SAV1 axis. To test this hypothesis, we generated conditional knock-in (KI) mice expressing non-Flna-binding mutant Sav1 in hepatocytes by crossing with mice carrying Cre recombinase driven by the serum albumin (alb) gene promoter. Unexpectedly, the insertion of the flox cassette skipped exon 2, resulting in a shorter Sav1 in all the transgenic mice. Since exon 2 encodes a fragment containing a Flna-binding domain, we analyzed both point mutant KI and exon 2-deleted mutant mice. Here we show that disruption of the Flna-Sav1 interaction in the mouse liver promotes apoptosis and suppresses tissue and organ growth without affecting the phosphorylation level of Yap1. These results provide evidence that the growth of animal tissues and organs is regulated by apoptosis downstream of the force-dependent FLNA-SAV1 interaction, at least in part.

Filamin A (FLNA) is a cytoplasmic actin binding protein, recently shown to be expressed as a long and short isoform. Mutations in FLNA are associated with a wide spectrum of disorders, including an X-linked form of chronic intestinal pseudo-obstruction (CIPO). However, the role of FLNA in intestinal development and function is largely unknown. In this study, we show that FLNA is expressed in the muscle layer of the small intestine from early human fetal stages. Expression of FLNA variants associated with CIPO, blocked expression of the long flna isoform and led to an overall reduction of RNA and protein levels. As a consequence, contractility of human intestinal smooth muscle cells was affected. Lastly, our transgenic zebrafish line showed that the flna long isoform is required for intestinal elongation and peristalsis. Histological analysis revealed structural and architectural changes in the intestinal smooth muscle of homozygous fish, likely triggered by the abnormal expression of intestinal smooth muscle markers. No defect in the localization or numbers of enteric neurons was observed. Taken together, our study demonstrates that the long FLNA isoform contributes to intestinal development and function. Since loss of the long FLNA isoform does not seem to affect the enteric nervous system, it likely results in a myopathic form of CIPO, bringing new insights to disease pathogenesis., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Filamin protein is characterized by an N-terminal actin-binding domain that is followed by 24 Ig (immunoglobulin)-like repeats, which act as hubs for interactions with a variety of proteins. In humans, this family has been found to be involved in cancer cell invasion and metastasis and can be involved in a variety of growth signal transduction processes, but it is less studied in plants. Therefore, in this study, 54 Filamin gene family members from 23 plant species were investigated and divided into two subfamilies: FLMN and GEX2. Subcellular localization showed that most of the Filamin gene family members were located in the cell membrane. A total of 47 Filamin gene pairs were identified, most of which were whole-genome copies. Through the analyses of cis -acting elements, expression patterns and quantitative fluorescence, it was found that GH&#95; A02G0519 and GH&#95; D02G0539 are mainly expressed in the reproductive organs of upland cotton, and their interacting proteins are also related to the fertilization process, whereas GH&#95;A02G0216 and GH&#95;D02G0235 were related to stress. Thus, it is speculated that two genes of the GEX2 subfamily ( GH&#95;A02G0519 and GH&#95;D02G0539 ) may be involved in the reproductive development of cotton and may affect the fertilization process of cotton. This study provides a theoretical basis for the further study of the cotton Filamin gene family.

Background: Tripartite motif (TRIM) proteins have been proved to contribute to cancer progression, while whether tripartite motif-containing 54 (TRIM54) could functionally influence gastric cancer (GC) progression remains elusive., Methods: The expression level of TRIM54 and filamin C (FLNC) in GC was determined by Western blot and online database. Cell Counting Kit-8 (CCK-8) assay, colony formation assay and Ethylenediurea (EdU) staining were performed to explore the effects of TRIM54 on GC cell proliferation. Transwell assay and wound healing assay were applied to detect the influence of TRIM54 on GC cell migration and invasion. Bioinformatics analysis and Co-immunoprecipitation assay (Co-Ip), Ubiquitination assay and Half-life assay were involved to explore the regulatory mechanism of TRIM54 on FLNC., Results: TRIM54 was upregulated in GC tissues and cells, and a higher expression level of TRIM54 indicated a shorter overall survival of GC patients. The overexpression of TRIM54 significantly enhanced proliferation, migration, and invasion of GC cells, and inhibition of TRIM54 expression exerted reverse effects on GC cells. Mechanistically, TRIM54 was determined as a post-translational mediator of FLNC, and TRIM54 was co-immunoprecipitated with FLNC and degraded its protein level via K63-linked ubiquitination of FLNC. Notably, FLNC efficiently inhibited GC progression by TRIM54 overexpression., Conclusion: Collectively, our findings suggested that the TRIM54/FLNC axis could be considered as a potential prognostic biomarker for GC., (© 2022 John Wiley & Sons Australia, Ltd.)

Rationale: Variable disease course and outcomes have been reported in children's interstitial lung disease associated with FLNA (Filamin A gene) variants. Objectives: To further delineate long-term respiratory outcomes and identify potential contributing factors to severe disease course. Methods: We retrospectively collected longitudinal data from three centers on nine cases (one male) with FLNA variants and early respiratory disease onset (within the first 24 mo of life). Clinical, radiographic, and histopathologic data were analyzed, focusing on cardiorespiratory disease course. Results: All required early respiratory support (three invasive ventilation, three noninvasive ventilation, three supplemental oxygen), and all experienced frequent severe infective respiratory exacerbations. Three died in infancy from refractory respiratory failure and pulmonary hypertension (PH). The six surviving individuals were 3, 10, 11, 15, 18, and 33 years old at time of reporting. The extent of functional respiratory impairment decreased with age; at last follow-up, there were no individuals on home invasive ventilation, one on nocturnal noninvasive ventilation, four on oxygen, and one on no respiratory support. Spirometry consistently demonstrated moderate to severe obstructive defects (forced expiratory volume in 1 s/forced vital capacity [FVC] z -score, -3.76 to -1.77; percent predicted FVC, 31.5% to 92.1%). Seven required PH treatment in early childhood (7/9), and three of the survivors (3/6) still receive treatment. Radiologic and histopathologic findings were consistent among cases. Conclusions: Early mortality was common, but many survivors stabilized even after severe symptoms in infancy. All survivors had persistent obstructive defects on spirometry, and half have persistent or recurrent PH. These typical findings are suggestive of this rare diagnosis and should prompt consideration of genetic testing.

Apoptosis is a critical process for the maintenance of cell populations, and involves mitochondrial depolarization, the sequential cleavage of caspase-9 and -3, followed by the externalization of phosphatidylserine (PS) on the plasma membrane. The actin cytoskeleton and its accessory proteins are known regulators of apoptotic signaling in nucleated cells but their roles in platelet apoptosis are undefined. Filamin A (FLNA) is a ubiquitously expressed actin-crosslinking protein that also serves as an intracellular signaling scaffold. Here we used platelets from mice with a platelet-specific FLNA deficiency (Flnafl/Y, Pf4-cre/+, termed platelet-specific knockout) to test the role of FLNA in platelet apoptosis. Treatment with the BH3-mimetic drug ABT-737 induced caspase-3 cleavage and PS exposure in platelets from floxed mice (Flnafl/Y, termed control) but these effects were essentially abrogated in FLNA-null platelets (platelet-specific knockout). Protein kinase C (PKC), a known FLNA ligand, was also activated by ABT-737, and PKC's phosphorylation of its downstream substrates was attenuated in FLNA-null platelets. The PKC inhibitor bisindolylmaleimide (BIM) also reduced caspase-3 cleavage, thus essentially phenocopying the FLNA-null platelets. Notably, the caspase-3 cleavage defect in FLNA-null platelets was rescued by the PKC-activating phorbol ester PMA, suggesting that FLNA and PKC share a common pathway in regulating platelet apoptosis. Mitochondrial depolarization and caspase-9 cleavage were unaffected by BIM treatment, suggesting that PKC specifically controls the downstream caspase-3 point of the pro-apoptotic signaling pathway. These data point to a novel role for FLNA in the regulation of platelet apoptosis, thus providing an improved understanding of how circulating platelet counts are maintained., (© 2022 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Sinus of Valsalva aneurysm (SVA) is a rare cardiovascular disease with male predominance. Recently, an association with aortic aneurysm and SVA has been revealed in periventricular nodular heterotopia patients with loss-of-function Filamin A (FLNA) mutations, which were located on chromosome X and almost exclusively affect females.Among patients hospitalized for aortic surgery with aortic root diameter over 4.0 cm, next-generation sequencing was performed to investigate 30 candidate genes related to inherited aortic aneurysm syndromes and familial thoracic aortic aneurysm and dissection. The present report reviewed an electronic case database and identified two female cases of unruptured SVA with heterozygous FLNA truncating mutations.Case 1 displaying a rare SVA phenotype involving left and noncoronary sinus harbored a nonsense variant p.Tyr1720Ter/c.5160C > G. Case 2 displayed right and noncoronary SVA with predominantly enlarged right coronary sinus, posterior mitral valve prolapse, and harbored a frameshift variant p.Val1724fs*68/c.5171&#95;5172delTG. Both novel mutations resulted in the premature termination of filamin A with the loss of functional Rod 2 and dimerization region.The present report raised the possibility of the presence of a cardiovascular onset form in the spectrum of FLNA hereditary diseases. The association between SVA and loss-of-function FLNA mutations indicates a unique etiology and pathogenesis among female patients, which requires further investigation to establish the linkage between FLNA variants and a wide spectrum of phenotypes.

We report a case of a 38-year-old female with an FLNA variant who underwent valve-sparing aortic root replacement. FLNA encodes Filamin A, an actin-binding protein. Our patient had aortic root dilation due to this variant. Aortic root repair was conducted using the David procedure, with modifications to account for tissue fragility associated with this genetic condition. This case demonstrates the value of patient-specific genetic information for the timing of surgery and operative course planning.

Background: Filaminopathies A are rare disorders affecting the brain, intestine, or skeleton, characterized by dominant X-linked filamin A (FLNA) gene mutations. Macrothrombocytopenia with functionally defective platelets is frequent. We have described a filaminopathy A male patient, exhibiting a C-terminal frame-shift FLNa mutation (Berrou et al., Arterioscler Thromb Vasc Biol. 2017;37:1087-1097). Contrasting with female patients, this male patient exhibited gain of platelet functions, including increased platelet aggregation, integrin αIIbβ3 activation, and secretion at low agonist concentration, raising the issue of thrombosis risk., Objectives: Our goal is to assess the thrombotic potential of the patient FLNa mutation in an in vivo model., Methods: We have established a mutant FlnA knock-in mouse model., Results: The mutant FlnA mouse platelets phenocopied patient platelets, showing normal platelet count, lower expression level of mutant FlnA, and gain of platelet functions: increased platelet aggregation, secretion, and αIIbβ3 activation, as well as increased spreading and clot retraction. Surprisingly, mutant FlnA mice exhibited a normal bleeding time, but with increased re-bleeding (77%) compared to wild type (WT) FlnA mice (27%), reflecting hemostatic plug instability. Again, in an in vivo thrombosis model, the occlusion time was not altered by the FlnA mutation, but arteriolar embolies were increased (7-fold more frequent in mutant FlnA mice versus WT mice), confirming thrombus instability., Conclusions: This study shows that the FlnA mutation found in the male patient induced gain of platelet functions in vitro, but thrombus instability in vivo. Implications for the role of FLNa in physiology of thrombus formation are discussed., (© 2022 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals LLC on behalf of International Society on Thrombosis and Haemostasis.)

Dilated cardiomyopathy (DCM) is a heterogeneous cardiac disorder characterized by left ventricular dilatation and dysfunction. Mutations in dozens of cardiac genes have been connected to the development of DCM including the filamin C gene (FLNC). We generated two induced pluripotent stem cell (iPSCs) lines from DCM patients carrying single missense heterozygote FLNC mutations (c.6689G > A and c.3745G > A). Both lines expressed high levels of pluripotency markers, differentiated into derivatives of the three germ layers and possessed normal karyotypes. The derived iPSC lines can serve as powerful tools to model DCM in vitro and as a platform for therapeutic development., 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 © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Filamins are large proteins with actin-binding properties. Mutations in FLNC, one of the three filamin genes in humans, have recently been implicated in dominant cardiomyopathies, but the underlying mechanisms are not well understood. Here, we aimed to use Drosophila melanogaster as a new in vivo model to study these diseases. First, we show that adult-specific cardiac RNAi-induced depletion of Drosophila Filamin (dFil) induced cardiac dilatation, impaired systolic function and sarcomeric alterations, highlighting its requirement for cardiac function and maintenance of sarcomere integrity in the adult stage. Next, we introduced in the cheerio gene, using CRISPR/Cas9 gene editing, three missense variants, previously identified in patients with hypertrophic cardiomyopathy. Flies carrying these variants did not exhibit cardiac defects or increased propensity to form filamin aggregates, arguing against their pathogenicity. Finally, we show that deletions of the C-term part of dFil carrying the last four Ig-like domains are dispensable for cardiac function. Collectively, these results highlight the relevance of this model to explore the cardiac function of filamins and increase our understanding of physio-pathological mechanisms involved in FLNC-related cardiomyopathies. This article has an associated First Person interview with the first author of the paper., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

Background: FLNC is one of the few genes associated with all types of cardiomyopathies, but it also underlies neuromuscular phenotype. The combination of concomitant neuromuscular and cardiac involvement is not often observed in filaminopathies and the impact of this on the disease prognosis has hitherto not been analyzed., Results: Here we provide a detailed clinical, genetic, and structural prediction analysis of distinct FLNC-associated phenotypes based on twelve pediatric cases. They include early-onset restrictive cardiomyopathy (RCM) in association with congenital myopathy. In all patients the initial diagnosis was established during the first year of life and in five out of twelve (41.7%) patients the first symptoms were observed at birth. RCM was present in all patients, often in combination with septal defects. No ventricular arrhythmias were noted in any of the patients presented here. Myopathy was confirmed by neurological examination, electromyography, and morphological studies. Arthrogryposes was diagnosed in six patients and remained clinically meaningful with increasing age in three of them. One patient underwent successful heart transplantation at the age of 18 years and two patients are currently included in the waiting list for heart transplantation. Two died due to congestive heart failure. One patient had ICD instally as primary prevention of SCD. In ten out of twelve patients the disease was associated with missense variants and only in two cases loss of function variants were detected. In half of the described cases, an amino acid substitution A1186V, altering the structure of IgFLNc10, was found., Conclusions: The present description of twelve cases of early-onset restrictive cardiomyopathy with congenital myopathy and FLNC mutation, underlines a distinct unique phenotype that can be suggested as a separate clinical form of filaminopathies. Amino acid substitution A1186V, which was observed in half of the cases, defines a mutational hotspot for the reported combination of myopathy and cardiomyopathy. Several independent molecular mechanisms of FLNC mutations linked to filamin structure and function can explain the broad spectrum of FLNC-associated phenotypes. Early disease presentation and unfavorable prognosis of heart failure demanding heart transplantation make awareness of this clinical form of filaminopathy of great clinical importance., (© 2022. The Author(s).)

Cancer development has been linked to aberrant sensing and interpretation of mechanical cues and force-generating properties. Here, we show that upregulation of the actin crosslinking protein Cheerio (Cher), the fly ortholog of Filamin A (FLNA), and the conformation of its mechanosensitive region (MSR) are instrumental to the malignancy of polarity-deficient, Ras-driven tumours in Drosophila epithelia. We demonstrate that impaired growth and cytoskeletal contractility of tumours devoid of cher can be rescued by stimulating myosin activity. Profiling the Cher interactome in tumour-bearing imaginal discs identified several components of the cell cortex, including the β-heavy Spectrin Karst (Kst), the scaffolding protein Big bang (Bbg), and 14-3-3ε. We show that Cher binds Bbg through the MSR while the interaction with 14-3-3ε and Kst is MSR-independent. Importantly, our genetic studies define Bbg, Kst, and 14-3-3ε as tumour suppressors. The tumour-promoting function of Cher thus relies on its capacity to control the contractile state of the cytoskeleton through interactions with myosin and specific components of the cell cortex., (© 2022 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Background: The FLNC gene has recently garnered attention as a likely cause of arrhythmogenic cardiomyopathy, which is considered an actionable genetic condition. However, the association with disease in an unselected clinical population is unknown. We hypothesized that individuals with loss-of-function variants in FLNC ( FLNC LOF ) would have increased odds for arrhythmogenic cardiomyopathy-associated phenotypes versus variant-negative controls in the Geisinger MyCode cohort., Methods: We identified rare, putative FLNC LOF among 171 948 individuals with exome sequencing linked to health records. Associations with arrhythmogenic cardiomyopathy phenotypes from available diagnoses and cardiac evaluations were investigated., Results: Sixty individuals (0.03%; median age 58 years [47-70 interquartile range], 43% male) harbored 27 unique FLNC LOF . These individuals had significantly increased odds ratios for dilated cardiomyopathy (odds ratio, 4.9 [95% CI, 2.6-7.6]; P <0.001), supraventricular tachycardia (odds ratio, 3.2 [95% CI, 1.1-5.6]; P =0.048), and left-dominant arrhythmogenic cardiomyopathy (odds ratio, 4.2 [95% CI, 1.4-7.9]; P =0.03). Echocardiography revealed reduced left ventricular ejection fraction (52±13% versus 57±9%; P =0.001) associated with FLNC LOF . Overall, at least 9% of FLNC LOF patients demonstrated evidence of penetrant disease., Conclusions: FLNC LOF variants are associated with increased odds of ventricular arrhythmia and dysfunction in an unselected clinical population. These findings support genomic screening of FLNC for actionable secondary findings.

The primary anatomical defect leading to periventricular nodular heterotopia occurs within the neural progenitors along the neuroepithelial lining of the lateral ventricles and results from a defect in the initiation of neuronal migration, following disruption of the neuroependyma and impaired neuronal motility. Growing evidence indicates that the FLNA -dependent actin dynamics and regulation of vesicle formation and trafficking by activation of ADP-ribosylation factors (ARFs) can play an important role in this cortical malformation. We report the first inherited variant of ARF1 in a girl with intellectual disability and periventricular nodular heterotopia who inherited the variant from the father with previously undiagnosed single nodular heterotopia and mild clinical expression. Additionally, both patients presented some features suggestive of hypohidrotic ectodermal dysplasia. These clinical features showed similarities to those of three previously reported cases with ARF1 missense variants, confirming that haploinsufficiency of this gene causes a recognisable neurological disorder with abnormal neuronal migration and variable clinical expressivity., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

A-to-I RNA editing by ADARs is an abundant epitranscriptomic RNA-modification in metazoa. In mammals, Flna pre-mRNA harbours a single conserved A-to-I RNA editing site that introduces a Q-to-R amino acid change in Ig repeat 22 of the encoded protein. Previously, we showed that FLNA editing regulates smooth muscle contraction in the cardiovascular system and affects cardiac health. The present study investigates how ADAR2-mediated A-to-I RNA editing of Flna affects actin crosslinking, cell mechanics, cellular adhesion and cell migration. Cellular assays and AFM measurements demonstrate that the edited version of FLNA increases cellular stiffness and adhesion but impairs cell migration in both, mouse fibroblasts and human tumour cells. In vitro, edited FLNA leads to increased actin crosslinking, forming actin gels of higher stress resistance. Our study shows that Flna RNA editing is a novel regulator of cytoskeletal organisation, affecting the mechanical property and mechanotransduction of cells., (© 2022 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Multivesicular bodies (MVBs) contain intralumenal vesicles that are delivered to lysosomes for degradation or released extracellularly for intercellular signaling. Here, we identified Caenorhabditis elegans filamin FLN-2 as a novel regulator of MVB biogenesis. FLN-2 co-localizes with V-ATPase subunits on MVBs, and the loss of FLN-2 affects MVB biogenesis, reducing the number of MVBs in C. elegans hypodermis. FLN-2 associates with actin filaments and is required for F-actin organization. Like fln-2(lf) mutation, inactivation of the V0 or V1 sector of V-ATPase or inhibition of actin polymerization impairs MVB biogenesis. Super-resolution imaging shows that FLN-2 docks V-ATPase-decorated MVBs onto actin filaments. FLN-2 interacts via its calponin-homology domains with F-actin and the V1-E subunit, VHA-8. Our data suggest that FLN-2 mediates the docking of MVBs on the actin cytoskeleton, which is required for MVB biogenesis., (© 2022 Shi et al.)

Mutations of filamin B ( FLNB ) gene can lead to a spectrum of autosomal skeletal malformations including spondylocarpotarsal syndrome (SCT), Larsen syndrome (LRS), type I atelosteogenesis (AO1), type III atelosteogenesis (AO3), and boomerang dysplasia (BD). Among them, LRS is milder while BD causes a more severe phenotype. However, the molecular mechanism underlying the differences in clinical phenotypes of different FLNB variants has not been fully determined. Here, we presented two patients suffering from autosomal dominant LRS and autosomal recessive vitamin D-dependent rickets type IA (VDDR-IA). Whole-exome sequencing revealed two novel missense variants in FLNB , c.4846A>G (p.T1616A) and c.7022T>G (p.I2341R), which are located in repeat 15 and 22 of filamin B, respectively. The expression of FLNB I2341R in the muscle tissue from our LRS patient was remarkably increased. And in vitro studies showed that both variants led to a lack of filopodia and accumulation of the mutants in the perinuclear region in HEK293 cells. We also found that c.4846A>G (p.T1616A) and c.7022T>G (p.I2341R) regulated endochondral osteogenesis in different ways. c.4846A>G (p.T1616A) activated AKT pathways through inhibiting SHIP2, suppressed the Smad3 pathway, and impaired the expression of Runx2 in both Saos-2 and ATDC5 cells. c.7022T>G (p.I2341R) activated both AKT and Smad3 pathways and increased the expression of Runx2 in Saos-2 cells, while in ATDC5 cells it activated AKT pathways through inhibiting SHIP2, suppressed the Smad3 pathway, and reduced the expression of Runx2. Our study demonstrated the pathogenic mechanisms of two novel FLNB variants in two different clinical settings and proved that FLNB variants could not only directly cause skeletal malformations but also worsen skeletal symptoms in the setting of other skeletal diseases. Besides, FLNB variants differentially affect skeletal development which contributes to clinical heterogeneity of FLNB-related disorders., Competing Interests: The authors declare no conflict of interest., (Copyright © 2022 Huixiao Wu et al.)

Cardiomyopathy affects approximately 1 in 500 adults and is the leading cause of death. Familial cases are common, and mutations in many genes are involved in cardiomyopathy, especially those in genes encoding cytoskeletal, sarcomere, and nuclear envelope proteins. Filamin C is an actin-binding protein encoded by filamin C (FLNC) gene and participates in sarcomere stability maintenance. FLNC was first demonstrated to be a causal gene of myofibrillar myopathy; recently, it has been found that FLNC mutation plays a critical role in the pathogenesis of cardiomyopathy. In this review, we summarized the physiological roles of filamin C in cardiomyocytes and the genetic evidence for links between FLNC mutations and cardiomyopathies. Truncated FLNC is enriched in dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Non-truncated FLNC is enriched in hypertrophic cardiomyopathy and restrictive cardiomyopathy. Two major pathomechanisms in FLNC-related cardiomyopathy have been described: protein aggregation resulting from non-truncating mutations and haploinsufficiency triggered by filamin C truncation. Therefore, it is important to understand the cellular biology and molecular regulation of FLNC to design new therapies to treat patients with FLNC-related cardiomyopathy., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Pathogenic variants of the X-linked FLNA gene encoding filamin A protein have been associated with a wide spectrum of symptoms, including the recently described pulmonary phenotype with childhood-onset panlobular emphysema. We describe three female patients from two families with novel heterozygous FLNA variants c.5837&#95;2del and c.508C > T. Analysis of immunofluorescence of peripheral blood smears and platelet function was performed for all patients. FLNA-negative platelets were observed, suggesting that these variants result in the loss of a functional protein product. All three patients also had periventricular nodular heterotopia and panlobular emphysema. However, they had considerably milder symptoms and later age of onset than in the previously reported cases. Therefore, patients with pathogenic FLNA variants should be studied actively for lung involvement even in the absence of pronounced respiratory symptoms. Conversely, any patient with unexplained panlobular emphysema should be analyzed for pathogenic FLNA variants. We also suggest that immunofluorescence analysis is a useful tool for investigating the pathogenicity of novel FLNA variants., (© 2022 The Authors. American Journal of Medical Genetics Part A published by Wiley Periodicals LLC.)

Background: Periventricular nodular heterotopia (PVNH) is caused by abnormal neuronal migration, resulting in the neurons accumulate as nodules along the surface of the lateral ventricles. PVNH often cause epilepsy, psychomotor development or cognition problem. Mutations in FLNA (Filamin A) is the most common underlying genetic etiology. Our purpose is to delineate the clinical and imaging spectrum that differentiates FLNA-positive and FLNA-negative PVNH patients., Methods: We included 21 patients with confirmed PVNH. The detailed clinical information, electroencephalography, and other clinical findings were recorded. Detailed brain MR imaging was assessed. Mutation analysis of the FLNA gene was used Sanger sequencing or a next generation sequencing based assay., Results: FLNA mutations were identified in 9 patients (7 females and 2 males), including two nonsense, two splice site, three frameshift, and two missense mutations. In FLNA-positive group, 8 patients had anterior predominant bilateral symmetric presentation and only one had asymmetrical distribution and dilated ventricles. Extra-cerebral features were more often observed in FLNA-positive group than FLNA-negative group., Conclusion: Genetics of PVNH is heterogenous, and mutations in FLNA gene account for less than half of the patients in our cohort. Our finding between FLNA-positive and FLNA-negative patients could guide the clinicians to select relevant genetic testing., Competing Interests: Conflicts of interest There is no conflict of interest regarding the publication of this study., (Copyright © 2021 Chang Gung University. Published by Elsevier B.V. All rights reserved.)

Background: Periventricular nodular heterotopia (PNH) is a cell migration disorder associated with mutations in Filamin-A (FLNA) gene on chromosome X. Majority of the individuals with PNH-associated FLNA mutations are female whereas liveborn males with FLNA mutations are very rare. Fetal viability of the males seems to depend on the severity of the variant. Splicing or severe truncations presumed loss of function of the protein product, lead to male lethality and only partial-loss-of-function variants are reported in surviving males. Those variants mostly manifest milder clinical phenotypes in females and thus avoid detection of the disease in females., Methods: We describe a novel p.Arg484Gln variant in the FLNA gene by performing whole exome analysis on the index case, his one affected brother and his healthy non-consanguineous parents. The transmission of PNH from a clinically asymptomatic mother to two sons is reported in a fully penetrant classical X-linked dominant mode. The variant was verified via Sanger sequencing. Additionally, we investigated the impact of missense mutations reported in affected males on the FLNa protein structure, dynamics and interactions by performing molecular dynamics (MD) simulations to examine the disease etiology and possible compensative mechanisms allowing survival of the males., Results: We observed that p.Arg484Gln disrupts the FLNa by altering its structural and dynamical properties including the flexibility of certain regions, interactions within the protein, and conformational landscape of FLNa. However, these impacts existed for only a part the MD trajectories and highly similar patterns observed in the other 12 mutations reported in the liveborn males validated this mechanism., Conclusion: It is concluded that the variants seen in the liveborn males result in transient pathogenic effects, rather than persistent impairments. By this way, the protein could retain its function occasionally and results in the survival of the males besides causing the disease., Competing Interests: The authors have declared that no competing interests exist.

Dilated cardiomyopathy (DCM) is a heterogenous group of disorders characterised by left ventricular dilatation and dysfunction, in the absence of factors affecting loading conditions such as hypertension or valvular disease, or significant coronary artery disease. The prevalence of idiopathic DCM is estimated between 1:250 and 1:500 individuals. Determining the aetiology of DCM can be challenging, particularly when evaluating an individual and index case with no classical history or investigations pointing towards an obvious acquired cause, or no clinical clues in the family history to suggest a genetic cause. We present a family affected by DCM associated with Filamin C variant, causing sudden cardiac death at a young age and heart failure due to severe left ventricular impairment and myocardial scarring. We review the diagnosis and treatment of DCM, its genetic associations and potential acquired causes. Thorough assessment is mandatory to risk stratify and identify patients who may benefit from primary prevention implantable cardioverter defibrillator therapy according to international guidelines. Genetic testing has some limitations, and is positive in only 20%-35% of DCM, but should be considered in specific cases to identify families who may benefit from cascade screening after appropriate counselling. The management of often complex familial cardiomyopathy requires specialist input for every case, and the appropriate infrastructure to coordinate investigations., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Tripartite motif-containing 44 (TRIM44) has recently been implicated in various pathological processes in numerous cancers, including lung adenocarcinoma (LUAD); however, its functional roles in chemoresistance are poorly understood. Herein, TRIM44 knockdown sensitized LUAD cells to cisplatin and enhanced cisplatin-induced apoptosis. Microarray analysis indicated that the " Role of BRCA1 in DNA damage " and the BRCA1 gene expression were positively regulated by TRIM44, which was further verified by immunofluorescence, qRT-PCR, and Western blotting. BRCA1 depletion effectively abolished TRIM44-modulated cisplatin resistance and regulation of homologous recombination (HR) repair. Interestingly, TRIM44 interacted with FLNA, an upstream regulator of BRCA1 as specified by STRING V 11.5, and facilitated its stability and deubiquitination. FLNA was also found to be required for the functions of TRIM44 in drug resistance. Using animal models, overexpression of TRIM44 was shown to confer resistance to cisplatin in a BRCA1- and FLNA-dependent manner. TRIM44 expression levels in tissues from cisplatin-resistant LUAD patients were significantly higher than those in tissues from cisplatin-sensitive LUAD patients. Collectively, our study results demonstrate that the TRIM44/FLNA/BRCA1 axis is involved in cisplatin chemoresistance, providing potential therapeutic targets for LUAD patients with cisplatin resistance., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Periventricular nodular heterotopia (PVNH) is an X-linked disease caused by loss-of-function variants in the filamin A ( FLNA ) gene. FLNA-PVNH is a heterogeneous disorder, and the phenotype is associated with neurological and non-neurological features including cardiovascular, gastrointestinal, pulmonary, haematological, cutaneous and skeletal manifestations. No clear definition of the FLNA-PVNH phenotype has been established, but the patients are predominantly females with seizures, cardiovascular manifestations, and normal intelligence or mild intellectual disability. Herein, we describe a PVNH patient diagnosed with a novel heterozygous missense variant in FLNA after an atypical presentation of deep vein thrombosis and thrombocytopenia. Clinical evaluation found hypermobility, cardiovascular and skin manifestations. Moreover, we conducted a literature review of 186 FLNA-PVNH patients to describe the phenotypic spectrum. In conclusion, our patient highlights the importance of thorough clinical evaluation to identify manifestations in this very heterogeneous disorder. The phenotypic review may guide clinicians in the assessment and follow-up of FLNA-PVNH patients., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Filamin A (FLNA) is an intracellular actin-binding protein, encoded by the FLNA gene, with a wide tissue expression. It is involved in several cellular functions, and extracellular matrix structuring. FLNA gene alterations lead to diseases with a wide phenotypic spectrum, such as brain periventricular nodular heterotopia (PVNH), cardiovascular abnormalities, skeletal dysplasia, and lung involvement., Clinical Findings: We present the case of a female infant who showed at birth aortic valve stenosis and PVNH, and subsequently developed interstitial lung disease with severe pulmonary hypertension., Primary Diagnosis: The association of aortic valve dysplasia, left ventricular outflow obstruction, persistent patent ductus arteriosus, and brain heterotopic gray matter suggested a possible FLNA gene alteration. A novel heterozygous intronic variant in the FLNA gene (NM&#95;001110556.1), c.4304-1G >A, was detected., Interventions: In consideration of valve morphology and severity of stenosis, the neonate was scheduled for a transcatheter aortic valvuloplasty. At 3 months of life, she developed hypoxemic respiratory failure with evidence of severe pulmonary hypertension. Inhaled nitric oxide (iNO) and milrinone on continuous infusion were started. Because of a partial response to iNO, an intravenous continuous infusion of sildenafil was introduced., Outcomes: In consideration of severe clinical course and fatal outcome, the new FLNA gene mutation described in our patient seems to be associated with a loss of function of FLNA., Practice Recommendations: Lung and brain involvement, in association with left ventricular outflow obstruction and persistent patency of ductus arteriosus, should be considered highly suggestive of FLNA gene alterations, in a female newborn., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 by The National Association of Neonatal Nurses.)

RNA polymerase III (pol III) products play fundamental roles in a variety of cellular processes, including protein synthesis and cancer cell proliferation. In addition, dysregulation of pol III-directed transcription closely correlates with tumorigenesis. It is therefore of interest to identify novel pathways or factors governing pol III-directed transcription. Here, we show that transcription factor (TF) GATA binding protein 4 (GATA4) expression in SaOS2 cells was stimulated by the silencing of filamin A (FLNA), a repressor of pol III-directed transcription, suggesting that GATA4 is potentially associated with the regulation of pol III-directed transcription. Indeed, we show that GATA4 expression positively correlates with pol III-mediated transcription and tumor cell proliferation. Mechanistically, we found that GATA4 depletion inhibits the occupancies of the pol III transcription machinery factors at the loci of pol III target genes by reducing expression of both TFIIIB subunit TFIIB-related factor 1 and TFIIIC subunit general transcription factor 3C subunit 2 (GTF3C2). GATA4 has been shown to activate specificity factor 1 (Sp1) gene transcription by binding to the Sp1 gene promoter, and Sp1 has been confirmed to activate pol III gene transcription by directly binding to both Brf1 and Gtf3c2 gene promoters. Thus, the findings from this study suggest that GATA4 links FLNA and Sp1 signaling to form an FLNA/GATA4/Sp1 axis to modulate pol III-directed transcription and transformed cell proliferation. Taken together, these results provide novel insights into the regulatory mechanism of pol III-directed transcription., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)