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Abstract Background Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder affecting women of reproductive ages. Our previous study has implicated a possible link between RNA editing and PCOS, yet the actual role of RNA editing, its association with clinical features, and the underlying mechanisms remain unclear. Methods Ten RNA-Seq datasets containing 269 samples of multiple tissue types, including granulosa cells, T helper cells, placenta, oocyte, endometrial stromal cells, endometrium, and adipose tissues, were retrieved from public databases. Peripheral blood samples were collected from twelve PCOS and ten controls and subjected to RNA-Seq. Transcriptome-wide RNA-Seq data analysis was conducted to identify differential RNA editing (DRE) between PCOS and controls. The functional significance of DRE was evaluated by luciferase reporter assays and overexpression in human HEK293T cells. Dehydroepiandrosterone and lipopolysaccharide were used to stimulate human KGN granulosa cells to evaluate gene expression. Results RNA editing dysregulations across multiple tissues were found to be associated with PCOS in public datasets. Peripheral blood transcriptome analysis revealed 798 DRE events associated with PCOS. Through weighted gene co-expression network analysis, our results revealed a set of hub DRE events in PCOS blood. A DRE event in the eukaryotic translation initiation factor 2-alpha kinase 2 (EIF2AK2:chr2:37,100,559) was associated with PCOS clinical features such as luteinizing hormone (LH) and the ratio of LH over follicle-stimulating hormone. Luciferase assays, overexpression, and knockout of RNA editing enzyme adenosine deaminase RNA specific (ADAR) showed that the ADAR-mediated editing cis-regulated EIF2AK2 expression. EIAF2AK2 showed a higher expression after dehydroepiandrosterone and lipopolysaccharide stimulation, triggering changes in the downstrean MAPK pathway. Conclusions Our study presented the first evidence of cross-tissue RNA editing dysregulation in PCOS and its clinical associations. The dysregulation of RNA editing mediated by ADAR and the disrupted target EIF2AK2 may contribute to PCOS development via the MPAK pathway, underlining such epigenetic mechanisms in the disease.

Background: Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder affecting women of reproductive ages. Our previous study has implicated a possible link between RNA editing and PCOS, yet the actual role of RNA editing, its association with clinical features, and the underlying mechanisms remain unclear. Methods: Ten RNA-Seq datasets containing 269 samples of multiple tissue types, including granulosa cells, T helper cells, placenta, oocyte, endometrial stromal cells, endometrium, and adipose tissues, were retrieved from public databases. Peripheral blood samples were collected from twelve PCOS and ten controls and subjected to RNA-Seq. Transcriptome-wide RNA-Seq data analysis was conducted to identify differential RNA editing (DRE) between PCOS and controls. The functional significance of DRE was evaluated by luciferase reporter assays and overexpression in human HEK293T cells. Dehydroepiandrosterone and lipopolysaccharide were used to stimulate human KGN granulosa cells to evaluate gene expression. Results: RNA editing dysregulations across multiple tissues were found to be associated with PCOS in public datasets. Peripheral blood transcriptome analysis revealed 798 DRE events associated with PCOS. Through weighted gene co-expression network analysis, our results revealed a set of hub DRE events in PCOS blood. A DRE event in the eukaryotic translation initiation factor 2-alpha kinase 2 (EIF2AK2:chr2:37,100,559) was associated with PCOS clinical features such as luteinizing hormone (LH) and the ratio of LH over follicle-stimulating hormone. Luciferase assays, overexpression, and knockout of RNA editing enzyme adenosine deaminase RNA specific (ADAR) showed that the ADAR-mediated editing cis-regulated EIF2AK2 expression. EIAF2AK2 showed a higher expression after dehydroepiandrosterone and lipopolysaccharide stimulation, triggering changes in the downstrean MAPK pathway. Conclusions: Our study presented the first evidence of cross-tissue RNA editing dysregulation in PCOS and its clinical associations. The dysregulation of RNA editing mediated by ADAR and the disrupted target EIF2AK2 may contribute to PCOS development via the MPAK pathway, underlining such epigenetic mechanisms in the disease. [ABSTRACT FROM AUTHOR]

Background Acute kidney injury (AKI) frequently occurs as a complication of sepsis. PANoptosis refers to a type of inflammatory programmed cell death that exhibits key characteristics of apoptosis, necroptosis, and pyroptosis. Here, we evaluated the role of absent in melanoma 2 (AIM2) and eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2) in septic AKI.Methods A septic AKI model was created through cecal ligation and puncture (CLP), while an in vitro model was developed using lipopolysaccharide (LPS)-stimulated HK2 cells. Hematoxylin and eosin (HE), Periodic acid-Schiff (PAS), and TUNEL staining were conducted to assess kidney injury in mice. Levels of serum creatinine (Scr) and blood urea nitrogen (BUN) were detected by kits. Gene expression was detected utilizing RT-qPCR, and Western blot was used to test protein levels. Immunofluorescence was employed to measure EIF2AK2 and AIM2 expression in mouse kidney tissue. Lactate dehydrogenase (LDH) activity assay was conducted to evaluate cytotoxicity. Co-immunoprecipitation (Co-IP) was performed to verify the binding relationship between EIF2AK2 and AIM2.Results AIM2 expression was increased in the renal tissue of mice subjected to CLP. Activation of the inflammasome and PANoptosis were observed in the renal tissue of CLP mice. AIM2 depletion attenuated PANoptosis in LPS-treated HK-2 cells. Additionally, EIF2AK2 could directly target AIM2, leading to a positive regulation of AIM2 expression. Notably, EIF2AK2 induced PANoptosis through upregulating AIM2 in HK-2 cells stimulated by LPS.Conclusions Our results revealed the important role of EIF2AK2-induced AIM2 upregulation in the activation of PANoptosis during septic AKI.

Dystonia is a progressive neurological motor disease with few treatment options and no cure. This review synthesizes the results of recent studies that implicate protein kinase R in mediating the molecular mechanisms of dystonia pathogenesis. Mutations in the PKR gene EIF2AK2 and the PKR activator protein PACT are associated with early-onset generalized dystonia. Protein kinase R (PKR) is important for neuronal function. Genetic depletion or inhibition of PKR is associated with increased long-term potentiation and memory, while also causing neuronal hyper-excitability and seizures in mouse models. PKR also senses double stranded RNA within cells and activates the integrated stress response (ISR). The ISR is a conserved signaling pathway that hinges on controlled translational suppression to remodel gene expression during stress. When PKR is activated through binding double stranded RNA or the PKR activator protein PACT, PKR dimerizes, autophosphorylates, and phosphorylates the translation initiation factor eIF2. Translation suppression by p-eIF2 causes stress granule formation and the upregulation of stress-induced genes. The ISR is thought to drive cellular resilience during acute stress. However, chronic ISR activation is associated with neurological diseases, traumatic brain injury, and aging. Neurodevelopmental and neurodegenerative diseases are associated with mutations in other integrated stress response genes, suggesting a critical role for ISR regulation in neuronal health. A growing body of work suggests the ISR is also dysfunctional in dystonia. Future research investigating the molecular mechanisms of the ISR in dystonia will likely reveal therapeutic targets and treatment strategies for this currently incurable disease. [ABSTRACT FROM AUTHOR]

Using chemoproteomic techniques, we first identified EIF2AK2, eEF1A1, PRDX3 and VPS4B as direct targets of berberine (BBR) for its synergistically anti-inflammatory effects. Of them, BBR has the strongest affinity with EIF2AK2 via two ionic bonds, and regulates several key inflammatory pathways through EIF2AK2, indicating the dominant role of EIF2AK2. Also, BBR could subtly inhibit the dimerization of EIF2AK2, rather than its enzyme activity, to selectively modulate its downstream pathways including JNK, NF-κB, AKT and NLRP3, with an advantage of good safety profile. In EIF2AK2 gene knockdown mice, the inhibitory IL-1β, IL-6, IL-18 and TNF-α secretion of BBR was obviously attenuated, confirming an EIF2AK2-dependent anti-inflammatory efficacy. The results highlight the BBR's network mechanism on anti-inflammatory effects in which EIF2AK2 is a key target, and inhibition of EIF2AK2 dimerization has a potential to be a therapeutic strategy against inflammation-related disorders.

Dystonia is a progressive neurological motor disease with few treatment options and no cure. This review synthesizes the results of recent studies that implicate protein kinase R in mediating the molecular mechanisms of dystonia pathogenesis. Mutations in the PKR gene EIF2AK2 and the PKR activator protein PACT are associated with early-onset generalized dystonia. Protein kinase R (PKR) is important for neuronal function. Genetic depletion or inhibition of PKR is associated with increased long-term potentiation and memory, while also causing neuronal hyper-excitability and seizures in mouse models. PKR also senses double stranded RNA within cells and activates the integrated stress response (ISR). The ISR is a conserved signaling pathway that hinges on controlled translational suppression to remodel gene expression during stress. When PKR is activated through binding double stranded RNA or the PKR activator protein PACT, PKR dimerizes, autophosphorylates, and phosphorylates the translation initiation factor eIF2. Translation suppression by p-eIF2 causes stress granule formation and the upregulation of stress-induced genes. The ISR is thought to drive cellular resilience during acute stress. However, chronic ISR activation is associated with neurological diseases, traumatic brain injury, and aging. Neurodevelopmental and neurodegenerative diseases are associated with mutations in other integrated stress response genes, suggesting a critical role for ISR regulation in neuronal health. A growing body of work suggests the ISR is also dysfunctional in dystonia. Future research investigating the molecular mechanisms of the ISR in dystonia will likely reveal therapeutic targets and treatment strategies for this currently incurable disease.

Abstract Background Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) accounts for more than half of total HCC patients in developing countries. Currently, HBV-related HCC diagnosis and prognosis still lack specific biomarkers. Here, we investigated if PRKRA expression in peripheral blood could be a potential biomarker for the diagnosis/prognosis of HBV-related HCC. Methods The expression of PRKRA in HBV-related HCC was firstly analyzed using TCGA and GEO databases. The results were confirmed in a validation cohort including 152 blood samples from 77 healthy controls and 75 HCC patients, 60 of which were infected with HBV. The potential diagnostic and prognostic values of PRKRA were also evaluated by the area under the receiver operator characteristic curve (AUROC) and Kaplan–Meier method, respectively. Results PRKRA was significantly upregulated in HCC patients, especially in those with HBV infections. In addition, the combination of PRKRA expression in peripheral blood with serum AFP and CEA levels displayed a better diagnostic performance (AUROC = 0.908, 95% CI 0.844–0.972; p

De novo pathogenic variants in EIF2AK2 have recently been reported as a novel genetic cause of leukoencephalopathy. Here, we describe a male individual who presented in the first year of life with clinical features resembling Pelizaeus-Merzbacher disease (PMD), including nystagmus, hypotonia, and global developmental delay, and which later progressed to include ataxia and spasticity. Brain MRI at the age of two revealed diffuse hypomyelination. This report adds to the limited number of individuals published and further reinforces de novo variants in EIF2AK2 as a molecular cause of a leukodystrophy that clinically and radiologically resembles PMD. [ABSTRACT FROM AUTHOR]

Mutations in Prkra gene, which encodes PACT/RAX cause early onset primary dystonia DYT-PRKRA, a movement disorder that disrupts coordinated muscle movements. PACT/RAX activates protein kinase R (PKR, aka EIF2AK2) by a direct interaction in response to cellular stressors to mediate phosphorylation of the α subunit of the eukaryotic translation initiation factor 2 (eIF2α). Mice homozygous for a naturally arisen, recessively inherited frameshift mutation, Prkralear-5J exhibit progressive dystonia. In the present study, we investigate the biochemical and developmental consequences of the Prkralear-5J mutation. Our results indicate that the truncated PACT/RAX protein retains its ability to interact with PKR, however, it inhibits PKR activation. Furthermore, mice homozygous for the mutation have abnormalities in the cerebellar development as well as a severe lack of dendritic arborization of Purkinje neurons. Additionally, reduced eIF2α phosphorylation is noted in the cerebellums and Purkinje neurons of the homozygous Prkralear-5J mice. These results indicate that PACT/RAX mediated regulation of PKR activity and eIF2α phosphorylation plays a role in cerebellar development and contributes to the dystonia phenotype resulting from this mutation., (© 2024. Published by The Company of Biologists Ltd.)

Background: Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) accounts for more than half of total HCC patients in developing countries. Currently, HBV-related HCC diagnosis and prognosis still lack specific biomarkers. Here, we investigated if PRKRA expression in peripheral blood could be a potential biomarker for the diagnosis/prognosis of HBV-related HCC. Methods: The expression of PRKRA in HBV-related HCC was firstly analyzed using TCGA and GEO databases. The results were confirmed in a validation cohort including 152 blood samples from 77 healthy controls and 75 HCC patients, 60 of which were infected with HBV. The potential diagnostic and prognostic values of PRKRA were also evaluated by the area under the receiver operator characteristic curve (AUROC) and Kaplan–Meier method, respectively. Results: PRKRA was significantly upregulated in HCC patients, especially in those with HBV infections. In addition, the combination of PRKRA expression in peripheral blood with serum AFP and CEA levels displayed a better diagnostic performance (AUROC = 0.908, 95% CI 0.844–0.972; p < 0.001). Notably, when serum AFP is less than 200 ng/mL, PRKRA expression demonstrated better diagnostic capability. Furthermore, PRKRA expression levels were associated with expression of EIF2AK2 and inflammatory cytokine genes. Conclusions: Triple combination testing of blood PRKRA expression, serum AFP and CEA levels could be a noninvasive strategy for diagnosis; and the elevation of PRKRA expression could predicate poor prognosis for HBV-related HCC. [ABSTRACT FROM AUTHOR]

Background: Acute kidney injury (AKI) frequently occurs as a complication of sepsis. PANoptosis refers to a type of inflammatory programmed cell death that exhibits key characteristics of apoptosis, necroptosis, and pyroptosis. Here, we evaluated the role of absent in melanoma 2 (AIM2) and eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2) in septic AKI., Methods: A septic AKI model was created through cecal ligation and puncture (CLP), while an in vitro model was developed using lipopolysaccharide (LPS)-stimulated HK2 cells. Hematoxylin and eosin (HE), Periodic acid-Schiff (PAS), and TUNEL staining were conducted to assess kidney injury in mice. Levels of serum creatinine (Scr) and blood urea nitrogen (BUN) were detected by kits. Gene expression was detected utilizing RT-qPCR, and Western blot was used to test protein levels. Immunofluorescence was employed to measure EIF2AK2 and AIM2 expression in mouse kidney tissue. Lactate dehydrogenase (LDH) activity assay was conducted to evaluate cytotoxicity. Co-immunoprecipitation (Co-IP) was performed to verify the binding relationship between EIF2AK2 and AIM2., Results: AIM2 expression was increased in the renal tissue of mice subjected to CLP. Activation of the inflammasome and PANoptosis were observed in the renal tissue of CLP mice. AIM2 depletion attenuated PANoptosis in LPS-treated HK-2 cells. Additionally, EIF2AK2 could directly target AIM2, leading to a positive regulation of AIM2 expression. Notably, EIF2AK2 induced PANoptosis through upregulating AIM2 in HK-2 cells stimulated by LPS., Conclusions: Our results revealed the important role of EIF2AK2-induced AIM2 upregulation in the activation of PANoptosis during septic AKI.

Background: Variants in EIF2AK2 have been recently associated with a spectrum of neurological disease encompassing isolated dystonia to fever‐related neurological decompensation, movement disorders and leukodystrophy. Case: A 32‐year old patient presented with childhood‐onset episodes of neurological decompensation after febrile illness, progressive anarthria, dystonia and spasticity. The T2/FLAIR MRI showed bilateral posterolateral putamen hyperintensities and white matter changes suggestive of leukodystrophy. Initial extensive metabolic workup and whole genome sequencing (WGS) was unremarkable. Re‐analysis of the WGS data revealed a variant in exon 3 of the EIF2AK2 gene [(NM_001135651.3): c.92C > G (p.Pro31Arg)]. EIF2AK2‐associated disorders should be incorporated into the differential diagnosis of the syndrome of fever‐related neurological decompensation with movement disorders, especially in the presence of abnormal neuroimaging. Literature review: Disease‐causing variants in EIF2AK2 have been reported in 24 individuals from 16 families in the literature to date. Two broad phenotypes have been described, including: (1) childhood‐onset generalized dystonia and a normal brain MRI; and (2) early childhood‐onset developmental delay combined with movement disorders, spasticity, and seizures in some. Notably, 92% of these patients have neurological deterioration after febrile illness or other physiological stress. Hypomyelination or delayed myelination and thin corpus callosum are seen in most patients and lower medullary lessions are common. Basal ganglia lesions have been reported previously in one case. Conclusions: EIF2AK2‐associated disorders should be incorporated into the differential diagnosis of the syndrome of fever‐related neurological decompensation with movement disorders, especially in the presence of abnormal neuroimaging. [ABSTRACT FROM AUTHOR]

Heterozygous EIF2AK2 Variant Causes Adolescence-Onset Generalized Dystonia Partially Responsive to DBS The missense variant NM 001135651( I EIF2AK2 i ):c.388G>C (p.Gly130Arg) was detected in the heterozygous state in a 28-year-old Algerian male who underwent whole-exome sequencing (WES) for adolescence-onset generalized dystonia with leg involvement.6 He was healthy until age 17, when he presented with dystonic posturing of the first two left fingers. [Extracted from the article]

Selective recognition and elimination of misfolded polypeptides are crucial for protein homeostasis. When the ubiquitin-proteasome system is impaired, misfolded polypeptides tend to form small cytosolic aggregates and are transported to the aggresome and eventually eliminated by the autophagy pathway. Despite the importance of this process, the regulation of aggresome formation remains poorly understood. Here, we identify TRIM28/TIF1β/KAP1 (tripartite motif containing 28) as a negative regulator of aggresome formation. Direct interaction between TRIM28 and CTIF (cap binding complex dependent translation initiation factor) leads to inefficient aggresomal targeting of misfolded polypeptides. We also find that either treatment of cells with poly I:C or infection of the cells by influenza A viruses triggers the phosphorylation of TRIM28 at S473 in a way that depends on double-stranded RNA-activated protein kinase. The phosphorylation promotes association of TRIM28 with CTIF, inhibits aggresome formation, and consequently suppresses viral proliferation. Collectively, our data provide compelling evidence that TRIM28 is a negative regulator of aggresome formation. Abbreviations: BAG3: BCL2-associated athanogene 3; CTIF: CBC-dependent translation initiation factor; CED: CTIF-EEF1A1-DCTN1; DCTN1: dynactin subunit 1; EEF1A1: eukaryotic translation elongation factor 1 alpha 1; EIF2AK2: eukaryotic translation initiation factor 2 alpha kinase 2; HDAC6: histone deacetylase 6; IAV: influenza A virus; IP: immunoprecipitation; PLA: proximity ligation assay; polypeptidyl-puro: polypeptidyl-puromycin; qRT-PCR: quantitative reverse-transcription PCR; siRNA: small interfering RNA [ABSTRACT FROM AUTHOR]

Mutations in Prkra gene, which encodes PACT/RAX cause early onset primary dystonia DYT-PRKRA, a movement disorder that disrupts coordinated muscle movements. PACT/RAX activates protein kinase R (PKR, aka EIF2AK2) by a direct interaction in response to cellular stressors to mediate phosphorylation of the α subunit of the eukaryotic translation initiation factor 2 (eIF2α). Mice homozygous for a naturally arisen, recessively inherited frameshift mutation, Prkra lear-5J exhibit progressive dystonia. In the present study, we investigate the biochemical and developmental consequences of the Prkra lear-5J mutation. Our results indicate that the truncated PACT/RAX protein retains its ability to interact with PKR, however, it inhibits PKR activation. Furthermore, mice homozygous for the mutation have abnormalities in the cerebellar development as well as a severe lack of dendritic arborization of Purkinje neurons. Additionally, reduced eIF2α phosphorylation is noted in the cerebellums and Purkinje neurons of the homozygous Prkra lear-5J mice. These results indicate that PACT/RAX mediated regulation of PKR activity and eIF2α phosphorylation plays a role in cerebellar development and contributes to the dystonia phenotype resulting from this mutation., Competing Interests: Financial Disclosure/Conflict of Interest: The authors declare no financial disclosures or conflicts of interest.

The global antimicrobial resistance crisis poses a significant threat to humankind in the coming decades. Challenges associated with the development of novel antibiotics underscore the urgent need to develop alternative treatment strategies to combat bacterial infections. Host-directed therapy is a promising new therapeutic strategy that aims to boost the host immune response to bacteria rather than target the pathogen itself, thereby circumventing the development of antibiotic resistance. However, host-directed therapy depends on the identification of druggable host targets or proteins with key functions in antibacterial defense. Protein Kinase R (PKR) is a well-characterized human kinase with established roles in cancer, metabolic disorders, neurodegeneration, and antiviral defense. However, its role in antibacterial defense has been surprisingly underappreciated. Although the canonical role of PKR is to inhibit protein translation during viral infection, this kinase senses and responds to multiple types of cellular stress by regulating cell-signaling pathways involved in inflammation, cell death, and autophagy – mechanisms that are all critical for a protective host response against bacterial pathogens. Indeed, there is accumulating evidence to demonstrate that PKR contributes significantly to the immune response to a variety of bacterial pathogens. Importantly, there are existing pharmacological modulators of PKR that are well-tolerated in animals, indicating that PKR is a feasible target for host-directed therapy. In this review, we provide an overview of immune cell functions regulated by PKR and summarize the current knowledge on the role and functions of PKR in bacterial infections. We also review the non-canonical activators of PKR and speculate on the potential mechanisms that trigger activation of PKR during bacterial infection. Finally, we provide an overview of existing pharmacological modulators of PKR that could be explored as novel treatment strategies for bacterial infections.

The global antimicrobial resistance crisis poses a significant threat to humankind in the coming decades. Challenges associated with the development of novel antibiotics underscore the urgent need to develop alternative treatment strategies to combat bacterial infections. Host-directed therapy is a promising new therapeutic strategy that aims to boost the host immune response to bacteria rather than target the pathogen itself, thereby circumventing the development of antibiotic resistance. However, host-directed therapy depends on the identification of druggable host targets or proteins with key functions in antibacterial defense. Protein Kinase R (PKR) is a well-characterized human kinase with established roles in cancer, metabolic disorders, neurodegeneration, and antiviral defense. However, its role in antibacterial defense has been surprisingly underappreciated. Although the canonical role of PKR is to inhibit protein translation during viral infection, this kinase senses and responds to multiple types of cellular stress by regulating cell-signaling pathways involved in inflammation, cell death, and autophagy – mechanisms that are all critical for a protective host response against bacterial pathogens. Indeed, there is accumulating evidence to demonstrate that PKR contributes significantly to the immune response to a variety of bacterial pathogens. Importantly, there are existing pharmacological modulators of PKR that are well-tolerated in animals, indicating that PKR is a feasible target for host-directed therapy. In this review, we provide an overview of immune cell functions regulated by PKR and summarize the current knowledge on the role and functions of PKR in bacterial infections. We also review the non-canonical activators of PKR and speculate on the potential mechanisms that trigger activation of PKR during bacterial infection. Finally, we provide an overview of existing pharmacological modulators of PKR that could be explored as novel treatment strategies for bacterial infections. [ABSTRACT FROM AUTHOR]

Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy comprise a group of neurodegenerative diseases termed synucleinopathies. Synucleinopathie are, characterized by presence of inclusion bodies in degenerating brain cells which contain aggregated α-synuclein phosphorylated on Ser129. Although the inflammation-associated serine-threonine kinase, PKR (EIF2AK2), promotes cellular protection against infection, we demonstrate a pro-degenerative role of activated PKR in an α-synuclein-dependent cell model of multiple system atrophy, where inhibition and silencing of PKR decrease cellular degeneration. In vitro phosphorylation demonstrates that PKR can directly bind and phosphorylate monomeric and filamenteous α-synuclein on Ser129. Inhibition and knockdown of PKR reduce Ser129 phosphorylation in different models (SH-SY5Y ASYN cells, OLN-AS7 cells, primary mouse hippocampal neurons, and acute brain slices), while overexpression of constitutively active PKR increases Ser129 α-syn phosphorylation. Treatment with pre-formed α-synuclein fibrils, proteostatic stress-promoting MG-132 and known PKR activators, herpes simplex virus-1-∆ICP34.5 and LPS, as well as PKR inducer, IFN-β-1b, lead to increased levels of phosphorylated Ser129 α-synuclein that is completely blocked by simultaneous PKR inhibition. These results reveal a direct link between PKR and the phosphorylation and toxicity of α-synuclein, and they support that neuroinflammatory processes play a role in modulating the pathogenicity of α-synuclein.

The RNA-dependent protein kinase (PKR), an eIF2α kinase plays an important role in anti-viral response, apoptosis and cell survival. It is also implicated to play a role in several cancers, metabolic and neurodegenerative disorders. A few ATP competitive inhibitors of the PKR have been reported in the literature with promising results in vitro and in vivo . The aim of this study was to unravel the structural interactions between these inhibitors and the PKR kinase domain using molecular simulations and docking. Our study reveals that the reported inhibitors bind in the adenine pocket and form hydrogen bonds with the hinge region and vdW interactions with non-polar residues in the binding site. The most potent inhibitor has several favorable interactions with the binding site and induces the P-loop to fold inward, creating a significant hydrophobic enclosure for itself. The computed binding free energies of these inhibitors are in accord with experimental data (IC 50 ). Strategies to design potent and selective PKR inhibitors are discussed to overcome the reported promiscuity. [ABSTRACT FROM AUTHOR]

The murine double-stranded RNA-binding protein termed protein kinase R (PKR)-associated protein X (RAX) and the human homolog, protein activator of PKR (PACT), were originally characterized as activators of PKR. Mice deficient in RAX show reproductive and developmental defects, including reduced body size, craniofacial defects and anterior pituitary hypoplasia. As these defects are not observed in PKR-deficient mice, the phenotype has been attributed to PKR-independent activities of RAX. Here we further investigated the involvement of PKR in the physiological function of RAX, by generating rax -/- mice deficient in PKR, or carrying a kinase-inactive mutant of PKR (K271R) or an unphosphorylatable mutant of the PKR substrate eukaryotic translation initiation factor α a subunit (eIF2α) (S51A). Ablating PKR expression rescued the developmental and reproductive deficiencies in rax -/- mice. Generating rax -/- mice with a kinase-inactive mutant of PKR resulted in similar rescue, confirming that the rax -/- defects are PKR dependent; specifically that the kinase activity of PKR was required for these defects. Moreover, generating rax -/- mice that were heterozygous for an unphosphorylatable mutant eIF2a provides partial rescue of the rax -/- defect, consistent with mutation of one copy of the Eif2s1 gene. These observations were further investigated in vitro by reducing RAX expression in anterior pituitary cells, resulting in increased PKR activity and induction of the PKR-regulated cyclin-dependent kinase inhibitor p21WAF1/CIP1. These results demonstrate that PKR kinase activity is required for onset of the rax -/- phenotype, implying an unexpected function for RAX as a negative regulator of PKR in the context of postnatal anterior pituitary tissue, and identify a critical role for the regulation of PKR activity for normal development. [ABSTRACT FROM AUTHOR]

Background: Variants in EIF2AK2 have been recently associated with a spectrum of neurological disease encompassing isolated dystonia to fever-related neurological decompensation, movement disorders and leukodystrophy., Case: A 32-year old patient presented with childhood-onset episodes of neurological decompensation after febrile illness, progressive anarthria, dystonia and spasticity. The T2/FLAIR MRI showed bilateral posterolateral putamen hyperintensities and white matter changes suggestive of leukodystrophy. Initial extensive metabolic workup and whole genome sequencing (WGS) was unremarkable. Re-analysis of the WGS data revealed a variant in exon 3 of the EIF2AK2 gene [ (NM&#95;001135651.3): c.92C > G (p.Pro31Arg)]. EIF2AK2 -associated disorders should be incorporated into the differential diagnosis of the syndrome of fever-related neurological decompensation with movement disorders, especially in the presence of abnormal neuroimaging., Literature Review: Disease-causing variants in EIF2AK2 have been reported in 24 individuals from 16 families in the literature to date. Two broad phenotypes have been described, including: (1) childhood-onset generalized dystonia and a normal brain MRI; and (2) early childhood-onset developmental delay combined with movement disorders, spasticity, and seizures in some. Notably, 92% of these patients have neurological deterioration after febrile illness or other physiological stress. Hypomyelination or delayed myelination and thin corpus callosum are seen in most patients and lower medullary lessions are common. Basal ganglia lesions have been reported previously in one case., Conclusions: EIF2AK2 -associated disorders should be incorporated into the differential diagnosis of the syndrome of fever-related neurological decompensation with movement disorders, especially in the presence of abnormal neuroimaging., Competing Interests: The authors report no specific grants for this research financial disclosure. No conflicts of interest are reported by the authors., (© 2021 International Parkinson and Movement Disorder Society.)