HERC2 deficiency activates C-RAF/MKK3/p38 signalling pathway altering the cellular response to oxidative stress

Autophagy dysregulation via the USP20-ULK1 axis in the HERC2-related neurodevelopmental disorder

Sequence variants in the HERC2 gene are associated with a significant reduction in HERC2 protein levels and cause a neurodevelopmental disorder known as the HERC2-related disorder, which shares clinical features with Angelman syndrome, including global developmental delay, intellectual disability, autism, and movement disorders. Remarkably, the HERC2 gene is commonly deleted in individuals with Angelman syndrome, suggesting a potential contribution of HERC2 to the pathophysiology of this disease. Given the known critical role of autophagy in brain development and its implication in neurodevelopmental diseases, we undertook different experimental approaches to monitor autophagy in fibroblasts derived from individuals affected by the HERC2-related disorder. Our findings reveal alterations in the levels of the autophagy-related protein LC3. Furthermore, experiments with lysosomal inhibitors provide confirmation of an upregulation of the autophagy pathway in these patient-derived cells. Mechanistically, we corroborate an interaction between HERC2 and the deubiquitylating enzyme USP20; and demonstrate that HERC2 deficiency leads to increased USP20 protein levels. Notably, USP20 upregulation correlates with enhanced stability of the autophagy initiating kinase ULK1, highlighting the role of HERC2 as an autophagy regulator factor through the USP20-ULK1 axis. Moreover, we show that p38 acts as a modulator of this pathway, since p38 activation disrupts HERC2-USP20 interaction, leading to increased USP20 and LC3-II protein levels. Together, these findings uncover a previously unknown role for HERC2 in autophagy regulation and provide insights into the pathomolecular mechanisms underlying the HERC2-related disorder and Angelman syndrome.

Identification of candidate SNPs and genes associated with resistance to nervous necrosis virus in leopard coral grouper (Plectropomus leopardus) using GWAS

The leopard coral grouper (Plectropomus leopardus), which has become increasingly popular in consumption due to its bright body color and great nutritional, holds a high economic and breeding potential. However, in recent years, the P.leopardus aquaculture industry has been impeded by the nervous necrosis virus (NNV) outbreak, leading to widespread mortality among fry and juvenile grouper. However, the genetic basis of resistance to NNV in P. leopardus remains to be investigated. In the present study, we conducted a genome-wide association analysis (GWAS) on 100 resistant and 100 susceptible samples to discover variants and potential genes linked with NNV resistance. For this study, 157,926 high-quality single nucleotide polymorphisms (SNPs) based on whole genome resequencing were discovered, and eighteen SNPs loci linked to disease resistance were discovered. We annotated six relevant candidate genes, including sik2, herc2, pip5k1c, npr1, mybpc3, and arhgap9, which showed important roles in lipid metabolism, oxidative stress, and neuronal survival. In the brain tissues of resistant and susceptible groups, candidate genes against NNV infection showed significant differential expression. The results indicate that regulating neuronal survival or pathways involved in lipid metabolism may result in increased resistance to NNV. Understanding the molecular mechanisms that lead to NNV resistance will be beneficial for the growth of the P. leopardus breeding sector. Additionally, the identified SNPs could be employed as biomarkers of disease resistance in P. leopardus, which will facilitate the selective breeding of grouper.

Comprehensive analysis of ferritinophagy-related genes and immune infiltration landscape in diabetic retinopathy

Background

Diabetic retinopathy (DR) is deemed a microangiopathy and neurodegenerative disorder, which is a primary reason of visual impairment in the world. Ferritinophagy is a critical regulator of ferroptosis and has a vital part in the etiopathogenesis of DR. Nevertheless, its molecular mechanism in DR remains to be expounded.

Methods

The GSE146615 dataset was adopted to identify ferritinophagy-related differentially expressed genes (FRDEGs). The interactions and biological functions of the genes were described by means of functional enrichment analysis (FEA). The enriched gene sets were analyzed utilizing gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA). Identification of hub genes was performed utilizing protein-protein interaction (PPI) analysis. mRNA-miRNA, mRNA-transcription factors (TF), mRNA-drugs, mRNA-RNA-binding proteins (RBP) interaction networks were constructed. In addition, datasets GSE60436 and GSE94019 were utilized for validation. The diagnostic performance of FRDEGs was assessed by means of receiver-operating characteristic curve monofactor analysis, followed by immune infiltration analysis. Lastly, quantitative real-time polymerase chain reaction (qRT-PCR) was implemented to analyze the validation of genes.

Results

In total, the identification of eight FRDEGs was completed utilizing differential expression analysis. FEA mainly implicated the autophagy of mitochondrion, mitochondrion disassembly, autophagosome assembly, and organization pathways. GSEA and GSVA mainly implicated the interferon alpha response, ultraviolet response up, interferon gamma response, apical junction, pical surface, and allograft rejection pathways. BECN1 and HERC2 displayed high diagnostic accuracies in validation sets. Immune infiltration analysis revealed that several immune cells related to ferritinophagy may be play potential roles in DR. Finally, qRT-PCR was utilized to validate the upregulated expression of BECN1 as well as the downregulated expression of BCAT2 and ATG7 in the DR model.

Conclusion

BECN1, HERC2, ATG7, and BCAT2 act as potential biomarkers for DR and might regulate ferritinophagy and the immune microenvironment to influence its development and progression. This research can provide new insights into pathogenesis of DR related to ferritinophagy.

Regulation of MAPK Signaling Pathways by the Large HERC Ubiquitin Ligases

Protein ubiquitylation acts as a complex cell signaling mechanism since the formation of different mono- and polyubiquitin chains determines the substrate's fate in the cell. E3 ligases define the specificity of this reaction by catalyzing the attachment of ubiquitin to the substrate protein. Thus, they represent an important regulatory component of this process. Large HERC ubiquitin ligases belong to the HECT E3 protein family and comprise HERC1 and HERC2 proteins. The physiological relevance of the Large HERCs is illustrated by their involvement in different pathologies, with a notable implication in cancer and neurological diseases. Understanding how cell signaling is altered in these different pathologies is important for uncovering novel therapeutic targets. To this end, this review summarizes the recent advances in how the Large HERCs regulate the MAPK signaling pathways. In addition, we emphasize the potential therapeutic strategies that could be followed to ameliorate the alterations in MAPK signaling caused by Large HERC deficiencies, focusing on the use of specific inhibitors and proteolysis-targeting chimeras.