Human Islets Contain a Beta Cell Type That Expresses Proinsulin But Not the Enzyme That Converts the Precursor to Insulin

Overview

Journal J Histochem Cytochem

Publisher Sage Publications

Specialty Biochemistry

Date 2020 Oct 1

PMID 32998631

Citations 2

Authors

Gladys Teitelman

Affiliations

Soon will be listed here.

Abstract

In pancreatic beta cells, proinsulin (ProIN) undergoes folding in endoplasmic reticulum/Golgi system and is translocated to secretory vesicles for processing into insulin and C-peptide by the proprotein convertases (PC)1/3 and PC2, and carboxypeptidase E. Human beta cells show significant variation in the level of expression of PC1/3, the critical proconvertase involved in proinsulin processing. To ascertain whether this heterogeneity is correlated with the level of expression of the prohormone and mature hormone, the expression of proinsulin, insulin, and PC1/3 in human beta cells was examined. This analysis identified a human beta cell type that expressed proinsulin but lacked PC1/3 (ProINPC1/3). This beta cell type is absent in rodent islets and is abundant in human islets of adults but scarce in islets from postnatal donors. Human islets also contained a beta cell type that expressed both proinsulin and variable levels of PC1/3 (ProINPC1/3) and a less abundant cell type that lacked proinsulin but expressed the convertase (ProINPC1/3). These cell phenotypes were altered by type 2 diabetes. These data suggest that these three cell types represent different stages of a dynamic process with proinsulin folding in ProINPC1/3 cells, proinsulin conversion into insulin in ProINPC1/3cells, and replenishment of the proinsulin content in ProINPC1/3 cells.

Citing Articles

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