Differential requirement for BRCA1-BARD1 E3 ubiquitin ligase activity in DNA damage repair and meiosis in the Caenorhabditis elegans germ line

Combined Transcriptomic and Mendelian Randomisation Explores the Diagnostic Value of Ubiquitination-Related Genes in Sepsis

Purpose

Sepsis is the 10th leading cause of death globally and the most common cause of death in patients with infections. Ubiquitination plays a key role in regulating immune responses during sepsis. This study combined bioinformatics and Mendelian randomization (MR) analyses to identify ubiquitin-related genes (UbRGs) with unique roles in sepsis.

Methods

Relevant genes were obtained from the GSE28750 dataset and GSE95233, weighted gene co-expression network analyses were performed to identify gene modules, and differentially expressed UBRGs (DE-UBRGs) were generated by differentially expressed genes (DEGs) crossover with key modular genes and UBRGs in sepsis and normal samples. Causal relationships between sepsis and UbRGs were analysed using MR, performance diagnostics were performed using subject work characteristics (ROC) curves, and an artificial neural network (ANN) model was developed. On this basis, immune infiltration was performed and the expression of key genes was verified in animal models.

Results

3022 DEGs were found between sepsis and normal. A total of 2620 genes were obtained as key modular genes. Crossing DEGs, key modular genes and UBRGs yielded 93 DE-UBRGs. MR results showed WDR26 as a risk factor for sepsis (OR>1) and UBE2D1 as a protective factor for sepsis (OR<1), which was reinforced by scatterplot and forest plot. ROC curves showed that WDR26 and UBE2D1 could accurately differentiate between sepsis and normal samples. Confusion matrix and ROC curve results indicate that the artificial neural network model has strong diagnostic ability. The results of immune infiltration showed that.WDR26 was negatively correlated with plasma cells, while UBE2D1 was positively correlated with CD4 naïve T cells. Significant differences between sepsis and normal were obtained between UBE2D1 and WDR26 in the animal model.

Conclusion

There appeared to be a causal relationship between sepsis, WDR26 and UBE2D1. The insights were of value for effective clinical diagnosis and treatment in sepsis.

The chromatin-associated 53BP1 ortholog, HSR-9, regulates recombinational repair and X chromosome segregation in the Caenorhabditis elegans germ line

53BP1 plays a crucial role in regulating DNA damage repair pathway choice and checkpoint signaling in somatic cells; however, its role in meiosis has remained enigmatic. In this study, we demonstrate that the Caenorhabditis elegans ortholog of 53BP1, HSR-9, associates with chromatin in both proliferating and meiotic germ cells. Notably, HSR-9 is enriched on the X chromosome pair in pachytene oogenic germ cells. HSR-9 is also present at kinetochores during both mitotic and meiotic divisions but does not appear to be essential for monitoring microtubule-kinetochore attachments or tension. Using cytological markers of different steps in recombinational repair, we found that HSR-9 influences the processing of a subset of meiotic double-stranded breaks into COSA-1-marked crossovers. Additionally, HSR-9 plays a role in meiotic X chromosome segregation under conditions where X chromosomes fail to pair, synapse, and recombine. Together, these results highlight that chromatin-associated HSR-9 has both conserved and unique functions in the regulation of meiotic chromosome behavior.

The chromatin-associated 53BP1 ortholog, HSR-9, regulates recombinational repair and X chromosome segregation in the Caenorhabditis elegans germ line

53BP1 plays a crucial role in regulating DNA damage repair pathway choice and checkpoint signaling in somatic cells; however, its role in meiosis has remained enigmatic. In this study, we demonstrate that the Caenorhabditis elegans ortholog of 53BP1, HSR-9, associates with chromatin in both proliferating and meiotic germ cells. Notably, HSR-9 is enriched on the X chromosome pair in pachytene oogenic germ cells. HSR-9 is also present at kinetochores during both mitotic and meiotic divisions but does not appear to be essential for monitoring microtubule-kinetochore attachments or tension. Using cytological markers of different steps in recombinational repair, we found that HSR-9 influences the processing of a subset of meiotic double strand breaks into COSA-1-marked crossovers. Additionally, HSR-9 plays a role in meiotic X chromosome segregation under conditions where X chromosomes fail to pair, synapse, and recombine. Together, these results highlight that chromatin-associated HSR-9 has both conserved and unique functions in the regulation of meiotic chromosome behavior.

53bp1 mutation enhances brca1 and bard1 embryonic lethality in C. elegans

In mice, mutation of brca1 results in embryonic lethality, which is partially suppressed by 53bp1 mutation. In contrast, mutation of the C. elegans BRCA1 ortholog, brc-1 , or its binding partner, brd-1 , lead to only mild embryonic lethality. We show that in C. elegans , brc-1 and brd-1 embryonic lethality is enhanced when 53bp1 ortholog, hsr-9 , is also mutated. This is not a consequence of activating polq-1 -dependent microhomology-mediated end joining, as polq-1 mutation does not suppress embryonic lethality of hsr-9 ; brc-1 mutants. Together, these results suggest that BRC-1 - BRD-1 and HSR-9 function in parallel pathways and do not act antagonistically as in mammals.