Stanniocalcin-1 Co-Localizes with Insulin in the Pancreatic Islets

الملخص EN

The polypeptide hormone stanniocalcin-1 (STC-1) is widely expressed in mammals and signals both locally and systemically.

In many tissues STC-1 ligand is sequestered by target cell organelles (mitochondria, nuclei, and cholesterol lipid droplets) to exert diverse biological effects.

Most notably, STC-1 serves as an uncoupler of oxidative phosphorylation in liver, muscle, and kidney mitochondria.

The present paper describes the identification of STC-1 receptors in mouse pancreatic β cells and the discovery that the ligand co-localizes with insulin in pancreatic β cells.

In situ hybridization (ISH) analysis subsequently revealed that pancreatic β cells were the source of the ligand.

Intriguingly however, all ISH signal was localized over putative islet cell nuclei as opposed to the cell cytoplasm.

Real-time qPCR and agarose gel electrophoresis revealed that the STC-1 amplicon generated from islet cell total RNA was the same size as that from kidney.

However, relative levels of STC-1 gene expression were >100-fold lower in islets than those in kidney tissue.

Collectively, these findings are indicative of a local STC-1 signalling pathway in pancreatic β cells.

The role of STC-1 in this context remains to be established, but it could very well entail the regulation of β cell mitochondria membrane potential which is an integral aspect of regulated insulin release.

Interestingly, STC-1 immunoreactivity was not evident in embryonic pancreatic islets, suggesting that ligand synthesis may only commence postnatally.