1730-P: Stochastic Differentiation of α-Cell Lineage Revealed by Single-Cell RNA Sequencing in Time-Resolved Reporter System
Authors: SHIMIZU NAOYA , SASAKI SHUGO , TAGUCHI TOMOMI , HIMURO MIWA , WATADA HIROTAKA , LYNN FRANCIS C. , MIYATSUKA TAKESHI 
Published: June 2023

Pancreatic α cells have attracted attention for their plasticity to be transdifferentiated into β cells that could potentially cure diabetes. Although such findings highlight the need for better understanding of α-cell biology, it remains unclear how each α cell originates from endocrine progenitors. We have recently generated a new α-cell reporter mouse, “Gcg-Timer” in which newly generated α (early α) cells can be sorted by FACS separately from more differentiated α (late α) cells. We investigated transcriptional heterogeneity between early and late α cells by bulk RNA sequencing (RNA-seq). To further elucidate α-cell heterogeneity at single-cell resolution, we sorted early and late α cells by FACS from E17.5 Gcg-Timer embryos, and performed single-cell RNA sequencing (scRNA-seq). Consistent with the results of bulk RNA-seq, violin plot analysis demonstrated that the mRNA expression levels of Ins1, Ins2, and Sst were significantly higher in early α cells than in late α cells. Surprisingly, pseudotime analysis demonstrated that the clusters of early α cells overlapped with those of late α cells, which means that the fluorescent reporter-based α-cell maturation does not reflect transcriptional maturation, which is in contrast with our recent finding that the fluorescent reporter-based β-cell maturation reflects transcriptional maturation based on scRNA-seq in “Ins1-eGFP;Timer” embryo. This unexpected finding suggests two possibilities: [1] each α cell stochastically originates from the endocrine progenitor pool, or [2] early α cells get differentiated in a stochastic manner. Thus, differentiation in α-cell lineage appears to be different from sequential differentiation in β-cell lineage, as we and others have demonstrated.

Disclosure
N.Shimizu: None. S.Sasaki: None. T.Taguchi: None. M.Himuro: Research Support; Japan Diabetes Society Junior Scientist Development Grant, Japan Society for the Promotion of Science. H.Watada: Research Support; Boehringer Ingelheim Japan, Inc., Mitsubishi Tanabe Pharma Corporation, LifeScan Diabetes Institute, Eli Lilly Japan K.K., Sun Pharmaceutical Industries Ltd., Teijin Pharma Limited, Taisho Pharmaceutical Holdings Co., Ltd., Ono Pharmaceutical Co., Ltd., Kowa Company, Ltd., Merck Sharp & Dohme Corp., Sanwa Kagaku Kenkyusho, Speaker's Bureau; Mitsubishi Tanabe Pharma Corporation, Taiho Pharmaceutical Co. Ltd., Novo Nordisk, Abbott Japan Co., Ltd., Astellas Pharma Inc., Merck Sharp & Dohme Corp., Kissei Pharmaceutical Co., Ltd., AstraZeneca, Ono Pharmaceutical Co., Ltd., Boehringer Ingelheim Japan, Inc., Sanofi, Sun Pharmaceutical Industries Ltd., Eli Lilly Japan K.K. F.C.Lynn: None. T.Miyatsuka: Speaker's Bureau; Eli Lilly Japan K.K., Novo Nordisk, Sanofi K.K., Mitsubishi Tanabe Pharma Corporation, Sumitomo Dainippon Pharma Co., Ltd., Teijin Pharma Limited, Sanwa Kagaku Kenkyusho, Daiichi Sankyo.

Funding
Japan Society for the Promotion of Science (21K16345, 20K08895, 19H04060); Japan Insulin-Dependent Diabetes Mellitus Network