Single-cell transcriptomics reveals novel pathways for expanding beta-cell mass
Chun Zeng1,2, Francesca Mulas1,2, Yinghui Sui1,2, Tiffany Guan1,2, Yuliang Tan2, Fenfen Liu1,2, Andrea C. Carrano1,2, Mark O. Huising3, Gene W. Yeo2, and Maike Sander1,2,*
1Department of Pediatrics, Pediatric Diabetes Research Center, University of California, San Diego, La Jolla, CA 92093, USA; 2Department of Cellular & Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; 3Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, Davis, CA 95616, USA
Pancreatic beta-cells are essential for maintaining blood glucose homeostasis and their loss or dysfunction leads to diabetes. A goal for diabetes therapy is to trigger regeneration of endogenous beta-cells by stimulating their proliferation. Beta-cell proliferative capacity declines rapidly postnatally, but the extrinsic cues and intracellular signals that cause this decline remain unknown. Insight gained by population-based transcriptome analysis has been limited because cell heterogeneity masks trends occurring across individual cells. To obtain a high-resolution map of beta-cell transcriptome dynamics after birth, we generated single-cell RNA-seq data of beta-cells from multiple postnatal time points. By developing a one-dimensional projection-based algorithm to order all profiled beta-cells based on transcriptional similarity, we were able to construct a “pseudotemporal” trajectory of postnatal beta-cell development. Our analysis captured signatures of immature, proliferative beta-cells and established high expression of amino acid metabolic, mitochondrial, and Atf/Jun/Fos transcription factor genes as their hallmark feature. Experimental validation demonstrated a role for amino acids and reactive oxygen species in postnatal beta-cell proliferation and mass expansion. Our work provides the first high-resolution molecular characterization of state changes in postnatal beta-cells and paves the way for the identification of novel therapeutic targets to stimulate beta-cell regeneration.