Project description:This SuperSeries is composed of the following subset Series: GSE29996: Deep sequencing of gastric carcinoma reveals somatic mutations relevant to personalized medicine [Affymetrix SNP array data] GSE29998: Deep sequencing of gastric carcinoma reveals somatic mutations relevant to personalized medicine [Illumina mRNA expression array data] Refer to individual Series
Project description:To better understand the homeostatic mechanisms governing melanocytes, we performed deep phenotyping of single-cell expansions of melanocytes from human skin. In total, we interrogated the mutational landscapes, gene expression profiles, and morphological features of 297 melanocytes from 31 donors. To our surprise, a population of melanocytes with low mutation burden was maintained in sun damaged skin. These melanocytes were more stem-like, smaller, and less dendritic than their counterparts with high mutation burdens. We used single-cell spatial transcriptomics (10X Xenium) to reveal the spatial distribution of melanocytes inferred to have low and high mutation burdens (LowMut and HighMut cells), based on their gene expression profiles. LowMut melanocytes were found in hair follicles as well as in the interfollicular epidermis, whereas HighMut melanocytes resided almost exclusively in the interfollicular epidermis. We propose that melanocytes in the hair follicle occupy a privileged niche, protected from UV radiation, but periodically migrate out of the hair follicle to replenish the interfollicular epidermis after waves of photodamage. More broadly, our study illustrates the advantages of a cell atlas that includes mutational information, as cells can change their cellular states and positional coordinates over time, but mutations are like scars, providing a historical record of the homeostatic processes that were operative on each cell.
Project description:In this study, we investigated somatic mutations of CD4+ and CD8+ T cells in patients with immune-mediated aplastic anemia (AA). To understand the role of mutations, we performed single-cell level analysis of 6 longitudinal samples of 2 AA patients carrying STAT3 or KRAS and other mutations in CD8+ T cells. The analysis was performed using V(D)J and 5' gene expression platform (10X Genomics). STAT3 mutated clone was clearly distinguishable from other CD8+ T cells and showed a cytotoxic phenotype, attenuated by successful immunosuppressive treatment. Our results suggest that somatic mutations in T cells can alter T cell phenotype warranting further investigation of their role in the pathogenesis of immune-mediated AA.
Project description:Reprogramming human somatic cells into induced pluripotent stem cells (iPSC) has been suspected of causing de novo copy number variations (CNVs). To explore this issue, we performed a whole-genome and transcriptome analysis of 20 human iPSC lines derived from primary skin fibroblasts of 7 individuals using next-generation sequencing. We find that, on average, an iPSC line manifests two CNVs not apparent in the fibroblasts from which the iPSC was derived. Using qPCR, PCR, and digital droplet PCR (ddPCR) to amplify across the CNVs' breakpoints, we show that at least 50% of those CNVs are present as low frequency somatic genomic variants in parental fibroblasts and are manifested in iPSC colonies due to their clonal origin. Hence, reprogramming does not necessarily lead to de novo CNVs in iPSC, since most of line-manifested CNVs reflect somatic mosaicism in the human skin. Moreover, our findings demonstrate that clonal expansion, and iPSC lines in particular, can be used as a discovery tool to reliably detect low frequency CNVs in the tissue of origin. Overall, we estimate that approximately 30% of the fibroblast cells have somatic CNVs, suggesting widespread somatic mosaicism in the human body. Our study paves the way to understanding the fundamental question of the extent to which cells of the human body normally acquire structural alterations in their DNA post-zygotically. We have generated and characterized hiPSC lines derived from skin fibroblasts collected from seven members of two families, which were competent to be differentiated into neuronal progenitors and neurons