Biology subjects

Yoo, Y. J.

Publications and source records attributed to Yoo, Y. J..

3 recordsLinked to original sources

bioRxiv2024

Dimension Reduction using Local Principal Components for Regression-based Multi-SNP Analysis in 1000 Genomes and the Canadian Longitudinal Study on Aging (CLSA)

For genetic association analysis based on multiple SNP regression of genotypes obtained by dense DNA sequencing or array data imputation, multi-collinearity can be a severe issue causing failure to fit the regression model. In this study, we proposed a method of Dimension Reduction using Local Principal Components (DRLPC) which aims to resolve multi-collinearity by removing SNPs under the assumption that the remaining SNPs can capture the effect of a removed SNP due to high linear dependency. This approach to dimension reduction is expected to improve the power of regression-based statistical tests. We apply DRLPC to chromosome 22 SNPs of two data sets, the 1000 Genomes Project (phase 3) and Canadian Longitudinal Study on Aging (CLSA), and calculated Variance Inflation Factors (VIF) in various SNP-sets before and after implementing DRLPC as a metric of collinearity. Notably, DRLPC addresses multi-collinearity by excluding variables with a VIF exceeding a predetermined threshold (VIF=20), thereby improving applicability for subsequent regression analyses. The number of variables in a final set for regression analysis is reduced to around 20% on average for larger-sized genes, whereas for smaller ones, the proportion is around 48%; suggesting that DRLPC is more effective for larger genes. We also compare the power of several multi-SNP statistics constructed for gene-specific analysis to evaluate power gains achieved by DRLPC. In simulation studies based on 100 genes with [≤]500 SNPs per gene, DRLPC effectively increased the power of the multiple regression Wald test from 60% to around 80%.

genetics↗

bioRxiv2024

RegionScan: A comprehensive R package for region-level genome-wide association testing with integration and visualization of multiple-variant and single-variant hypothesis testing

SummaryRegionScan is an R package for comprehensive and scalable genome-wide association testing of region-level multiple-variant and single-variant statistics and visualization of the results. It implements various state-of-the-art region-level tests to improve signal detection under heterogeneous genetic architectures and facilitates comparison of multiple-variant region-level and single-variant test results. It exploits local linkage disequilibrium (LD) structure for genomic partitioning and LD-adaptive region definition. RegionScan is compatible with VCF input file formats for genotyped and imputed variants, and options are available for analysis of multi-allelic variants and unbalanced binary phenotypes. It accommodates parallel region-level processing and analysis to improve computational time and memory efficiency and provides detailed outputs and utility functions to assist results comparison, visualization, and interpretation. Availability and implementationRegionScan is freely available for download on GitHub (https://github.com/brossardMyriam/RegionScan). Contactbull@lunenfeld.ca, brossard@lunenfeld.ca. Supplementary informationSupplementary data are available at Bioinformatics online.

genetics↗

bioRxiv2022

Dual states of Bmi1-expressing intestinal stem cells drive epithelial development and tissue regeneration

Intestinal development, response to injury and disease states rely upon balanced stem cell proliferation. Historically, two subtypes of intestinal epithelial stem cells (ISCs)--slow-cycling/label-retaining, and actively-cycling/canonical Wnt-dependent--coordinate to drive proliferation and regulate epithelial renewal during adult tissue homeostasis and injury response. Recent studies focused on Bmi1-expressing cells revealed that differentiated Bmi1+ enteroendocrine cells could dedifferentiate towards a canonical Wnt-dependent stem cell state, calling into question the dogma that a dual stem cell axis regulates epithelial proliferation. Herein, we identify stem cell function in a Bmi1+ cell population in early murine intestinal development prior to the establishment of canonical Wnt-dependent, Lgr5-expressing ISCs. In-depth analyses of developmental Bmi1+ ISCs using lineage-tracing and single cell RNA-sequencing reveal their distinct identity and capacity to differentiate into Lgr5+ ISCs and other differentiated lineages. Further, during in utero development, the Bmi1+ ISCs initially exists in a highly proliferative state then transitions to a slow-cycling state, with the emergence of actively-cycling Lgr5+ ISCs. In adult tissue, Bmi1+ ISCs are a distinct population that re-express developmental gene and protein profiles, and a non-canonical Wnt signaling signature in response to injury and in human colorectal tumors. Further, developmental Bmi1+ ISCs are distinct from Lgr5+ ISCs and the previously identified differentiated Bmi1+ progenitor cells. Re-evaluation of an under-appreciated Bmi1+ ISC population with fundamental importance in intestinal development re-establishes the importance of the dynamic interplay between discrete ISC populations that are regulated by opposing Wnt signaling pathways. This finding opens opportunities and targetable pathways to augment regeneration or inhibit tumorigenesis.

developmental biology↗