👤 Mahesh K Basantani

White adipose tissue (WAT) expansion occurs through generation of new adipocytes from adipose progenitor cells (APC). The objective of this study was to characterize and validate a new transcriptional profile of APC. Single-cell (sc)/nuclei (sn) RNA-Seq was performed on nuclei from whole WAT (n = 20), cells from WAT stromal vascular fraction (n = 5), and cultured APC in vitro (n = 8) using ICELL8 smart-Seq technology. Additional snRNA-Seq was performed on WAT using 10x genomic platform. Pseudotime analyses and differentiation of hiPSCs was used to track the temporal patterns of novel gene signatures. Immunohistochemistry was performed to validate a new marker. A pre-adipocyte population was found across the four independent datasets that expressed known pre-adipocyte markers (ZNF423 and DLK1) in addition to genes typically associated with neurogenes (DPP10, PTRPT, CTNNA2, NRXN3, CTNNA2, PTPRD, CNTNAP2 and RBFOX1). The expression of these genes were temporally regulated with adipocyte differentiation. Immunohistochemistry analyses confirmed these pre-adipocytes are located in the neurovascular niche of WAT but are not neurons or endothelial cells. This work has defined a new transcriptional signature of pre-adipocytes in human subcutaneuous WAT that are distinct from mesencyhmal stem cell populations and represent novel targets for WAT expansion. Show less

Glucose stimulates rodent and human β-cell replication, but the intracellular signaling mechanisms are poorly understood. Carbohydrate response element-binding protein (ChREBP) is a lipogenic glucose-sensing transcription factor with unknown functions in pancreatic β-cells. We tested the hypothesis that ChREBP is required for glucose-stimulated β-cell proliferation. The relative expression of ChREBP was determined in liver and β-cells using quantitative RT-PCR (qRT-PCR), immunoblotting, and immunohistochemistry. Loss- and gain-of-function studies were performed using small interfering RNA and genetic deletion of ChREBP and adenoviral overexpression of ChREBP in rodent and human β-cells. Proliferation was measured by 5-bromo-2'-deoxyuridine incorporation, [(3)H]thymidine incorporation, and fluorescence-activated cell sorter analysis. In addition, the expression of cell cycle regulatory genes was measured by qRT-PCR and immunoblotting. ChREBP expression was comparable with liver in mouse pancreata and in rat and human islets. Depletion of ChREBP decreased glucose-stimulated proliferation in β-cells isolated from ChREBP(-/-) mice, in INS-1-derived 832/13 cells, and in primary rat and human β-cells. Furthermore, depletion of ChREBP decreased the glucose-stimulated expression of cell cycle accelerators. Overexpression of ChREBP amplified glucose-stimulated proliferation in rat and human β-cells, with concomitant increases in cyclin gene expression. In conclusion, ChREBP mediates glucose-stimulated proliferation in pancreatic β-cells. Show less