Glucocorticoid receptor activation induces bipotent and endocrine commitment in human in vitro-derived pancreatic progenitors

SILVIO A. TRABA; LUCAS BACIGALUPO; AGUSTÍN ROMERO; SANTIAGO A. RODRÍGUEZ SEGUÍ

Mar del Plata

Congreso; Sociedad Argentina de Investigaciones Clínicas; 2023

The in vitro production of functional β-cells for transplantation in type 1 diabetic patients is a long standing challenge that could suppress insulin administration. It has been shown that while conditional deletion of glucocorticoid receptor (GR) in Pdx1+ progenitors (an thus from the beginning of pancreas specification) increases β-cell mass, its deletion from the β-cell stage does not have the same effect. To gain insights into this mechanism, here, we profiled the transcriptomic changes of in vitro derived pancreatic multipotent progenitor cells (MPCs) treated with Dexamethasone (Dex, a known GR agonist) or control (Ethanol) at the single-cell level (scRNA-seq). Analysis of these data, combined with the MPC epigenomic profile and scRNA-seq profiled in the human embryonic pancreas, revealed the induction of genes with a known role in pancreas development, as well as other transcripts with yet unknown functions. Taken together, our results suggest that activation of the GR in this model induces MPC differentiation to endocrine progenitors (EPs). In sharp contrast, a similar treatment with Dex in E11.5 embryonic mouse pancreatic explants (composed mostly of MPCs at this stage) induced cell commitment to the acinar fate. These results were supported by immunofluorescence and RT-qPCR (p<0.05) for key genes which were regulated by Dex in the human pancreatic differentiation model. To assess the potential mechanisms underlying this difference, we performed E11.5 mouse pancreatic explants culture in the presence of Dex with or without  Dkk-1 (an inhibitor of the Wnt pathway, known to induce acinar differentiation in MPCs), as well as their corresponding controls. Our preliminary results show that treatment with Dkk-1 enhances the expression of genes involved in EP differentiation. Future work aims at evaluating in more detail the effects of the combined treatment, ultimately revealing how the GR might tune MPC differentiation towards the endocrine fate.