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Variants at type 2 diabetes (T2D) and related trait genome wide association study (GWAS) signals may impact T2D risk via skeletal muscle, a primary insulin responsive tissue. We previously generated in vivo single nucleus (sn-)multi-omics (RNA+ATAC) profiling of 286 skeletal muscle biopsies from the FUSION Tissue Biopsy Study and found that a subset of GWAS signals colocalize with cell-type specific e/caQTL active in fibro-adipogenic progenitors (FAPs). In a subset of 50 of these individuals, we derived induced pluripotent stem cell (iPSC) lines from fibroblasts. We hypothesize that FAPs can be differentiated from iPSC lines to investigate the impact of FAP-specific molecular mechanisms on T2D risk and T2D-related traits. Here, we demonstrate that FAPs can be derived from iPSC lines for deep molecular phenotyping. These iPSC-derived FAPs display FAP morphology, expression of FAP marker genes, and loss of expression of pluripotency markers. Over the course of the differentiation, PODXL, a pluripotency marker, drops from 99.1% of cells expressing this down to 0.19%, based on flow cytometry analysis. Meanwhile, expression of NT5E, a FAP marker, increases from 0.095% of cells up to 98.9%. We performed a time course analysis with 10 independent iPSC lines, all multiplexed into a cell village, to explore the trajectory from iPSCs to FAPs. A logistic regression between cell type specific chromatin accessibility peaks of the iPSC-FAPs and skeletal muscle cell types reveals the chromatin accessibility profile of iPSC-FAPs to be very similar to in vivo FAPs, indicating that the differentiated FAPs can be used as a model system to characterize FAPs. We are currently upscaling the experiment to 40 iPSC-derived FAP samples to investigate stimulatory state specific genetic regulatory effects (e/caQTL) within T2D pathways. We will validate our results by performing CRISPRi knockdown and CRISPRa activation on a subset of nominated loci. Disclosure C. Ventresca: None. A. Varshney: None. P. Orchard: None. Y. Tsan: None. A. Monteiro da rocha: None. M. Laakso: None. J. Tuomilehto: Stock/Shareholder; Orion Pharma, Aktivolabs, Digostics. T.A. Lakka: None. K.L. Mohlke: None. M. Boehnke: None. L. Scott: None. H.A. Koistinen: Other Relationship; AstraZeneca, Novo Nordisk. F.S. Collins: None. T.J. Herron: None. S. Bielas: None. S. Parker: Research Support; Pfizer Inc. Funding National Institutes of Health (1F31DK135342-01A1); National Institutes of Health (R01DK117960); University of Michigan (UM1DK126185)
Ventresca et al. (Fri,) studied this question.