Developmental and metabolic programming of ß cell progenitors

• Applicants: Tiago Cardoso Alves, Ph.D.; Professor Anthony Gavalas, Ph.D.
• Subject Area: Endocrinology, Diabetology, Metabolism ; Developmental Biology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 507249020

Developmental programming of embryonic pancreas progenitors prepares nascent ß cells for the postnatal expansion and maturation that ensure ß cell function. Disturbances during development may result in ß cell dysfunction due to epigenetic changes but the underlying molecular mechanisms are not understood. Aldehyde dehydrogenase 1b1 (Aldh1b1), a mitochondrial enzyme, is expressed in all pancreas progenitors but not in mature cells and it regulates the timing of pancreas differentiation. Its functional inactivation in mice resulted in premature differentiation and several genes important for ß cell function were already misregulated in postnatal day 1 (P1) islets. Null mice were hyperglycaemic, had glucose intolerance, lacked first phase insulin secretion and isolated adult null islets responded poorly to glucose. Preliminary results have shown that loss of Aldh1b1 function in pancreatic progenitors results in lower mitochondrial membrane potential, increased levels of reactive oxygen species (ROS) and loss of self-renewal. Thus we hypothesize that Aldh1b1 regulates the metabolism of pancreas progenitors and their epigenetic patterning since variations in the concentration of certain metabolites regulate the activity of histone and DNA modifying enzymes. Consistent with our hypothesis, preliminary results indicated a deficit in cytosolic Acetyl-CoA generation. To understand the role of Aldh1b1 in the metabolism of the pancreas progenitors we will use metabolomics and metabolic flux analyses of wild type, Aldh1b1 null and Aldh1b1 overexpressing pancreatic progenitors to unveil the Aldh1b1-regulated metabolic pathways as well as in vitro recombinant enzyme assays to identify the likely substrate(s) of Aldh1b1. The results will be validated using in vitro perturbation and rescue experiments. To address the importance of Aldh1b1 driven metabolism in gene expression and chromatin structure during differentiation and ß cell maturation, we will conduct RNA-Seq, ATAC-Seq and EM-Seq experiments in embryonic pancreas progenitors and ß cells at 14.5 dpc and P1 in wild type and Aldh1b1 null mice. Changes in chromatin accessibility and DNA methylation patterns will be correlated with changes in gene expression to decipher gene regulatory networks implicated in ß-cell developmental programming and maturation. The findings will provide metabolites and metabolic pathways implicated in pancreas progenitor self-renewal, endocrine differentiation and ß cell maturation. This will be important for applications seeking to generate ß cells from pluripotent stem cells or endogenous pancreas adult stem cells for diabetes disease modelling and therapy. They may also have implications for addressing the development of pancreatic cancer since we have recently found that KrasG12D dependent pancreatic cancer in a mouse model requires a functional Aldh1b1.

• DFG Programme: Research Grants