Biology subjects

Kilaru, V.

Publications and source records attributed to Kilaru, V..

5 recordsLinked to original sources

bioRxiv2023

Evolving Membrane-Associated Accessory Protein Variants for Improved Adeno-Associated Virus Production

Manufacturing sufficient Adeno-Associated Virus (AAV) to meet current and projected clinical needs is a significant hurdle to the growing gene therapy industry. The recently discovered membrane-associated accessory protein (MAAP) is encoded by an alternative open reading frame in the AAV cap gene that is found in all presently reported natural serotypes. Recent evidence has emerged supporting a functional role of MAAP in AAV egress, though the underlying mechanisms of MAAP function remain unknown. Here, we show that inactivation of MAAP from AAV2 by a single point mutation that is silent in the VP1 ORF (AAV2-{Delta}MAAP) decreased exosome-associated and secreted vector genome production. We hypothesized that novel MAAP variants could be evolved to increase AAV production and thus subjected a library encoding over 1E6 MAAP protein variants to five rounds of packaging selection into the AAV2-{Delta}MAAP capsid. Between each successive packaging round, we observed a progressive increase in both overall titer and ratio of secreted vector genomes conferred by the bulk selected MAAP library population. Next-generation sequencing uncovered enriched mutational features, and a resulting selected MAAP variant containing missense mutations and a novel C-terminal domain increased overall GFP transgene packaging in AAV2, AAV6, and AAV9 capsids.

bioengineering↗

bioRxiv2022

Genetic dissection of crossover mutants defines discrete intermediates in mouse meiosis

Crossovers, the exchange of homolog arms, are required for accurate segregation during meiosis. Studies in yeast have established that the single end invasion intermediate is highly regulated to ensure crossover distribution. Single end invasions are thought to differentiate into double Holliday junctions that are resolved by MutLgamma (MLH1/3) into crossovers. Currently, we lack knowledge of early steps of mammalian crossover recombination or how intermediates are differentiated in any organism. Using comprehensive analysis of recombination and cytology, we infer that polymerized single-end invasion intermediates and nicked double Holliday junctions are crossover precursors in mouse spermatocytes. In marked contrast to yeast, MLH3 plays a structural role to differentiate single end invasions into double Holliday junctions with differentially polymerized 3 ends. Therefore, we show independent genetic requirements for precursor formation and asymmetry with regard to 3 end processing, providing mechanistic insight into crossover formation and patterning.

genetics↗

bioRxiv2020

Methylation Quantitative Trait Loci are Largely Consistent across Disease States in Crohns disease

BackgroundIn a recent study, we identified 1189 CpG sites whose DNA methylation (DNAm) level in blood distinguished Crohns disease (CD) cases from controls. We also demonstrated that the vast majority of these differences were a consequence of disease, rather than a cause of CD. Since methylation can be influenced by both genetic and environmental factors, here we focus on CpGs under demonstrable genetic control (methylation quantitative trait loci, or mQTLs). By comparing mQTL patterns across disease states and tissue (blood vs. ileum), we may distinguish patterns unique to CD. Such DNAm patterns may be relevant for the developmental origins of CD. MethodsWe investigated three datasets: (i) 402 blood samples from 164 newly diagnosed pediatric CD patients taken at two time points, and 74 non-IBD controls (ii) 780 blood samples from a non-CD adult population and (iii) 40 ileal biopsies (17 CD cases and 23 non-IBD controls) from group (i). Genome-wide DNAm profiling and genotyping were performed using the Illumina MethylationEPIC and Illumina Multi-Ethnic arrays. SNP-CpG associations were tested via linear models adjusted for age, gender, disease status, disease subtype, estimated cell type and three genotype-based principal components. We used a Bonferroni-adjusted significance threshold to identify significantly associated SNP-CpG pairs, but also considered larger sets identified by a false discovery rate criterion ResultsIn total, we observed 535,448 SNP-CpG associations between 287,881 SNPs and 12,843 CpG sites (P<8.21x10-14). These associations and their effects are highly consistent across different ages, races, disease states, and tissue types, suggesting that the vast majority of these mQTLs participate in common gene regulation. However, genes near CpGs associated with IBD SNPs were enriched for 18 KEGG pathways relevant to IBD-linked immune function and inflammatory responses. We observed suggestive evidence for a small number of tissue-specific associations and disease-specific ileal associations in ileum, though larger studies will be needed to confirm these results. ConclusionThe vast majority of blood derived mQTLs are commonly shared across individuals. However, we have identified a subset of such, which may be involved in processes related to CD. Independent cohort studies will be required to validate these findings.

genomics↗

bioRxiv2019

Epigenome-wide meta-analysis of PTSD across 10 military and civilian cohorts identifies novel methylation loci

Differences in susceptibility to posttraumatic stress disorder (PTSD) may be related to epigenetic differences between PTSD cases and trauma-exposed controls. Such epigenetic differences may provide insight into the biological processes underlying the disorder. Here we describe the results of the largest DNA methylation meta-analysis of PTSD to date with data from the Psychiatric Genomics Consortium (PGC) PTSD Epigenetics Workgroup. Ten cohorts, military and civilian, contributed blood-derived DNA methylation data (HumanMethylation450 BeadChip) from 1,896 PTSD cases (42%) and trauma-exposed controls (58%). Utilizing a common QC and analysis strategy, we identified ten CpG sites associated with PTSD (9.61E-07<p<4.72E-11) after adjustment for multiple comparisons (FDR<.05). Several CpGs were located in genes previously implicated in PTSD and other psychiatric disorders. The top four CpG sites fell within the aryl-hydrocarbon receptor repressor (AHRR) locus and were associated with lower DNA methylation in PTSD cases relative to controls. Interestingly, this association appeared to uncorrelated with smoking status and was most pronounced in non-smokers with PTSD. Additional evaluation of metabolomics data supported our findings and revealed that AHRR methylation associated with kynurenine levels, which were lower among subjects with PTSD relative to controls. Overall, this study supports epigenetic differences in those with PTSD and suggests a role for decreased kynurenine as a contributor to immune dysregulation in PTSD.

genomics↗

bioRxiv2017

Characterization of Gene Expression Changes Over Healthy Term Pregnancies

During pregnancy, women experience numerous physiological changes but, to date, there is limited published data that characterize accompanying changes in gene expression over pregnancy. This study sought to characterize the complexity of gene expression over the course of pregnancy among women with healthy pregnancies. Subjects provided a venous blood sample during early (6-15 weeks) and late (22-33 weeks) pregnancy, which was used to isolate peripheral blood mononuclear cells prior to RNA extraction. Gene expression was examined for 63 women with uncomplicated, term deliveries. We evaluated the association between weeks gestation at sample collection and expression of each transcript. Of the 16,311 transcripts evaluated, 439 changed over pregnancy after a Bonferroni correction to account for multiple comparisons. Genes whose expression changed over pregnancy were associated with oxygen transport, the immune system, and host response to bacteria. Characterization of changes in gene expression over the course of healthy term pregnancies may enable the identification of genes whose expression predicts complications or adverse outcomes of pregnancy.

genomics↗