A single-cell atlas of de novo β-cell regeneration reveals the contribution of hybrid β/δ-cells to diabetes recovery in zebrafish

Abstract

Regeneration-competent species possess the ability to reverse the progression of severe diseases by restoring the function of the damaged tissue. However, the cellular dynamics underlying this capability remain unexplored. Here, we use single-cell transcriptomics to map the cellular dynamics underlying de novo β-cell regeneration during induction and recovery from diabetes in zebrafish. We show that the zebrafish has evolved two distinct types of somatostatin-producing δ-cells, which we term δ1- and δ2-cells. Moreover, we characterize a small population of glucose-responsive islet cells, which share the hormones and fate-determinants of both β- and δ1-cells. The transcriptomic analysis of β-cell regeneration reveals that the development of β/δ hybrid cells constitutes a prominent source of insulin-expression during diabetes recovery. Using in vivo calcium imaging and cell tracking, we further show that the hybrid cells form de novo upon β-cell loss and acquire glucose-responsiveness in the course of regeneration. The overexpression of dkk3, a gene enriched in hybrid cells, increases their formation in the absence of β-cell injury. Our data provide an atlas of β-cell regeneration and indicate that the rapid formation of glucose-responsive hybrid cells contributes to the resolution of diabetes in zebrafish.

A δ-cell subpopulation with a pro-β-cell identity contributes to efficient age-independent recovery in a zebrafish model of diabetes

“…Their capacity to regulate blood glucose levels is corroborated by their transcriptomic profile showing the expression of the machinery required for glucose responsiveness and insulin secretion as illustrated by the glucose transporter Glut2 (slc2a2), the prohormone convertase pcsk1, the K ATP subunit SUR1 (abcc8) and several components of the secretory pathway. All these findings are further supported by the observation by Singh et al that β/δ hybrid cells gain glucose responsiveness during regeneration as assessed by in vivo Calcium imaging (Singh et al, 2021). Altogether, we propose that, despite the fact that bihormonal cells are not identical to β-cells, they are the functional units that control glucose homeostasis in regenerated fish, compensate for the absence of monohormonal β-cells and reverse diabetes.…”

“…All these observations support the conclusion that sst1.1 -cells constitute a distinct zebrafish -cell population expressing -cell features enabling them to rapidly reprogram to bihormonal cells by activating ins expression and engender functional surrogate-cells. Importantly, during the preparation of our manuscript, Singh et al also identified sst1.1+ ins+ δ/β hybrid cells in zebrafish by scRNAseq (Singh et al, 2021). They also proposed the sst1.1 -cells as possible cellular origin after β-cell ablation, thereby consolidating our findings.…”

Global Host Responses to the Microbiota at Single Cell Resolution in Gnotobiotic Zebrafish

“…These analyses reveal how microbiota stimulate both tissue growth and function, promoting developmental plasticity in response to the microbial environment. The transcriptional plasticity of pancreatic cells has also been demonstrated at single cell resolution within regenerating islets of the zebrafish endocrine pancreas (Singh et al ., 2022). In the artificial GF state, the exocrine pancreas appears to be stunted and composed of fully differentiated acinar cells that, based on their transcriptional patterns, are poised in a functionally inactive state, a situation that may require upregulation of cytoprotective Cry proteins to maintain.…”

Zebrafish pancreatic β cell clusters undergo stepwise regeneration using Neurod1-expressing cells from different cell lineages

“…Most previous zebra sh studies have focused on the phase of functional recovery, which we identi ed in this study. They reported that α cells, δ1 cells, β/δ1 hybrid cells, and some endocrine progenitor cells contribute to β cell regeneration 5,[8][9][10]16 . Our current results suggest that these cells already express Neurod1 or express Neurod1 within 24 hours after β cell ablation and that Neurod1 expression is a common characteristic of cells which give rise to the regeneration of β cells.…”