GSE137909
Characterizing pancreatic ß-cell heterogeneity in the streptozotocin model by single-cell transcriptomic analysis
Objectives The streptozotocin (STZ) model is widely used in diabetes research. However, the cellular and molecular states of pancreatic endocrine cells in this model remain unclear. This study explored the molecular characteristics of islet cells treated with STZ and re-evaluated ß-cell dysfunction and regeneration in the STZ model. Methods We performed single-cell RNA sequencing of pancreatic endocrine cells from STZ-treated mice. High-quality sequencing data from 2,999 cells were used to identify clusters via Louvain clustering analysis. Principal component analysis (PCA), t-distributed stochastic neighbor embedding (t-SNE), uniform manifold approximation and projection (UMAP), force-directed layout (FDL), and differential expression analysis were used to define the heterogeneity and transcriptomic changes in islet cells. In addition, qPCR and immunofluorescence staining were used to confirm findings from the sequencing data. Results Untreated ß-cells were divided into two populations at the transcriptomic level, a large high-Glut2 expression (Glut2high) population and a small low-Glut2 expression (Glut2low) population. At the transcriptomic level, Glut2low ß-cells in adult mice did not represent a developmentally immature state, although a fraction of genes associated with ß-cell maturation and function were downregulated in Glut2low cells. After a single high-dose STZ treatment, most Glut2high cells were killed, but Glut2low cells survived and over time changed to a distinct cell state. We did not observe conversion of Glut2low to Glut2high ß-cells up to 9 months after STZ treatment. In addition, we did not detect transcriptomic changes in the non-ß endocrine cells or a direct trans-differentiation pathway from the a-cell lineage to the ß-cell lineage in the STZ model. Conclusions We identified the heterogeneity of ß-cells in both physiological and pathological conditions. However, we did not observe conversion of Glut2low to Glut2high ß-cells, transcriptomic changes in the non-ß endocrine cells, or direct trans-differentiation from the a-cell lineage to the ß-cell lineage in the STZ model. Our results clearly define the states of islet cells treated with STZ and allow us to re-evaluate the STZ model widely used in diabetes studies. Overall design: To explore the transcriptomic status of individual pancreatic endocrine cells in STZ-treated mice, we isolated cells from STZ-treated mice by fluorescence-activated cell sorting (FACS) and performed single-cell RNA sequencing (scRNA-seq) using a modified STRT-seq (mSTRT-seq) approach. To enrich endocrine cells, RFP+ cells were collected from Ngn3-Cre; Rosa-RFP mice. Mice were treated with a single high dose (200 mg/kg) of STZ and were assessed from day 1 (D6) to month 9 (M9). Additionally, to evaluate the maturation status of ß-cells, we performed mSTRT-seq on Ngn3-Cre; Rosa-RFP+ cells from postnatal day (P) 3, P12, and P21 mice.