Indran, S. | bioRxiv Science

bioRxiv2024

A multi-model approach defines function altering MECP2 missense variants identified in individuals with autism spectrum disorder

Pathogenic variants in MECP2 commonly lead to Rett syndrome, where MECP2s function as a DNA cytosine methylation reader is believed critical. MECP2 variants are also catalogued in individuals with autism spectrum disorder (ASD), including nine missense variants which had no known clinical significance at the start of this study. To assess these nine variants as risk alleles for ASD, we developed MECP2 variant functional assays using budding yeast and Drosophila. We calibrated these assays with known pathogenic and benign variants. Our data predict that four ASD variants are loss of function and five are functional. Protein destabilization offers insight into the altered function of some of these variants. Notably, yeast and Drosophila lack DNA methylation, yet all Rett pathogenic and ASD variants located in the methyl DNA binding domain that we analyzed proved to be loss of function, suggesting a clinically-relevant role for non-methyl DNA-binding by MECP2.

neuroscience↗

bioRxiv2023

Identification of host factor for Rift valley fever Phlebovirus

BackgroundRift Valley fever phlebovirus (RVFV) is a zoonotic pathogen that causes Rift Valley fever (RVF) in livestock and humans. Currently, there is no licensed human vaccine or antiviral drug to control RVF. Although multiple species of animals and humans are vulnerable to RVFV infection, host factors affecting susceptibility are not well understood. MethodologyTo identify the host factors or genes essential for RVFV replication, we conducted a CRISPR-Cas9 knock-out screen in human A549 cells. We then validated the putative genes using siRNA-mediated knockdowns and CRISPR-Cas9-mediated knockout studies, respectively. The role of a candidate gene in the virus replication cycle was assessed by measuring intracellular viral RNA accumulation, and the virus titers by plaque assay or TCID50 assay. FindingsWe identified approximately 900 genes with potential involvement in RVFV infection and replication. Further evaluation of the effect of six genes on viral replication using siRNA-mediated knockdowns found that silencing two genes (WDR7 and LRP1) significantly impaired RVFV replication. For further analysis, we focused on the WDR7 gene since the role of LRP1 in RVFV replication was previously described in detail. Knock-out A549 cell lines were generated and used to dissect the effect of WRD7 on RVFV and another bunyavirus, La Crosse encephalitis virus (LACV). We observed significant effects of WDR7 knock-out cells on both intracellular RVFV RNA levels and viral titers. At the intracellular RNA level, WRD7 affected RVFV replication at a later phase of its replication cycle (24h) when compared to LACV which was affected an earlier replication phase (12h). ConclusionIn summary, we have identified WDR7 as an essential host factor for the replication of two relevant bunyaviruses, RVFV and LACV. Future studies will investigate the mechanistic role by which WDR7 facilitates Phlebovirus replication. Authors SummaryRift Valley fever phlebovirus is a high consequence pathogen that infects multiple animal species and also humans. Currently, there are no control measures available to treat RVF in humans and to prevent the incursion of Rift Valley fever virus into non-endemic countries. RVFV poses a significant threat to animal and human health in countries where it is endemic. RVFV replication depends on the hosts machinery to complete its replication cycle. Therefore, one way to control virus replication is to disrupt the interaction between the virus and the host proteins important for replication. In this study, we identified a host factor, the WDR7 gene, that is critical for RVFV replication. The identification of this host factor is important as it can potentially lead to the development of antiviral strategies to control Rift Valley fever in both humans and animals.

microbiology↗