Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2019) 65 P197 | DOI: 10.1530/endoabs.65.P197

1Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK; 2Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK; 3Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, Neuherberg, Germany; 4Section of Cell Biology and Functional Genomics, Imperial College London, London, UK; 5Division of Regenerative Medicine, Department of Medicine, Weill Cornell Medical College, New York, USA


Background: A normal islet includes both mature and immature β-cells, with the former possessing higher insulin content and the latter displaying better proliferative capacity. However, it remains unknown whether immature β-cells also contribute to the regulation of insulin release, especially by commanding the activity of their mature counterparts.

Materials and methods: Pdx1, Mafa, and Ngn3 were overexpressed in β-cells by either transduction with adenovirus (Ad-M3C) or using a doxycycline-inducible mouse line (RIP7rtTA+/-; TetO/M3C+/- (Tet-MAT)). Conditional chemogenetic β-cell silencing was achieved in islets expressing the inhibitory DREADD h4MDi under the control of the Ins1Cre driver line (D-MAT). Confocal microscopy, coupled with biosensors or organic dyes, was used for measurement of Ca2+, cAMP and ATP/ADP. HTRF assay was used to measure insulin secretion. RNAseq was performed using Lexogen QuantSeq 3’ mRNA-Seq. Glucose tolerance was assessed by intraperitoneal glucose tolerance test.

Results: Pdx1 and Mafa expression levels were increased, while Ngn3 showed no change. PDX1 and MAFA overexpression was largely restricted to PDX1LOW/MAFALOW β-cells (defined as immature β-cells), and confirmed using Pdx1-BFP islets reporting historic cell PDX1 levels. Loss of immature β-cells presented with impaired islet Ca2+, cAMP and ATP/ADP fluxes, as well as insulin secretion in response to glucose and/or Exendin-4. RNAseq analyses revealed dysregulation of gene pathways involved in carbohydrate and lipid analysis, and upregulation of transcripts involved in inhibitory signalling. Chemogenetic silencing in D-MAT islets showed that immature β-cells were dependent on islet Ca2+ signaling dynamics for their phenotype. Induction of immature β-cell loss in vivo by placing the Tet-MAT animals on doxycycline diet for 2 weeks resulted in glucose intolerance.

Conclusion: The current study redefines immature β-cells as a functionally competent, but islet-dependent β-cell subpopulation. Findings from single-cell screening studies or studies in dissociated cells should be interpreted carefully in light of differences arising from the islet context.

Volume 65

Society for Endocrinology BES 2019

Brighton, United Kingdom
11 Nov 2019 - 13 Nov 2019

Society for Endocrinology 

Browse other volumes

Article tools

My recent searches

No recent searches.