Scharfmann, R. | bioRxiv Science

bioRxiv2018

Comparison of human and murine enteroendocrine cells by transcriptomic and peptidomic profiling

Enteroendocrine cells (EECs) produce hormones that regulate food absorption, insulin secretion and appetite. Both EECs and their peptide products are foci of drug discovery programmes for diabetes and obesity. We compared the human and mouse EEC transcriptome and peptidome to validate mouse as a model of the human enteroendocrine axis. We present the first RNA sequencing analysis of human EECs, and demonstrate strong correlation with mouse, although with outliers including some low abundance G-protein coupled receptors. Liquid chromatography mass spectrometry (LC-MS) identified peptide hormone gradients along the human and mouse gut that should enhance progress in gut physiology and therapeutics.

cell biology↗

bioRxiv2017

Electrophysiological properties of human β-cell lines EndoC-βH1 and -βH2 conform with human β-cells

The electrophysiological and secretory properties of the human {beta}-cell lines EndoC-{beta}H1 and EndoC-{beta}H2 were investigated. Both cell lines respond to glucose (6-20mM) with 2-to 3-fold stimulation of insulin secretion, an effect that was mimicked by tolbutamide (0.2mM) and reversed by diazoxide (0.5mM). Glucose-induced insulin release correlated with an elevation of [Ca2+]i, membrane depolarization and increased action potential firing. KATP channel activity at 1mM glucose is low and increasing glucose to 6 or 20mM reduced KATP channel activity to the same extent as application of the KATP channel blocker tolbutamide (0.2mM). The upstroke of the action potentials in EndoC-{beta}H1 and -{beta}H2 cells observed at high glucose principally reflects activation of L- and P/Q-type Ca2+ channels with some small contribution of TTX-sensitive Na+ channels. Action potential repolarization involves activation of voltage-gated Kv2.2 channels and large-conductance Ca2+-activated K+ channels. Exocytosis (measured by measurements of membrane capacitance) was triggered by membrane depolarizations >10ms to membrane potentials above -30mV. Both cell lines were well-granulated (6,000-15,000 granules/cell) and granules consisted of a central insulin core surrounded by a clear halo. We conclude that the EndoC-{beta}H1 and -{beta}H2 cells share many features of primary human {beta}-cells and that they represent a useful experimental model.

cell biology↗