<b>Localization of diacylglycerol kinase ζ in rat pancreatic islet cells under normal and streptozotocin-induced stress </b><b>conditions </b>

Abstract

The pancreas comprises exocrine and endocrine portions, the latter of which is a glucose-responsive tissue that secretes hormones in response to serum glucose levels. One pathway implicated in the regulatory mechanism of this gland is the phosphoinositide (PI) cycle, which generates second messengers. Diacylglycerol (DG), the major second messenger in the PI signaling cascade, is catalyzed by the diacylglycerol kinase (DGK) family. We previously described characteristic expression and localization patterns of DGKs in various organs under pathophysiological conditions. Nevertheless, little is known about the characteristics and morphological aspects of this enzyme family in the pancreas. This study was conducted to investigate the pancreas, specifically the expression and localization of the DGK family. RT-PCR analysis reveals that DGKζ is the major isozyme in the pancreas. Additionally, we show that DGKζ is expressed in pancreatic islet cells, but not in the exocrine cells. It localizes predominantly to the nuclei of α-, β-, and δ-cells. We found further that DGKζ translocates from the nucleus to the cytoplasm in β-cells in response to a β-cell-selective toxin streptozotocin (STZ) and that it disappears over time. These findings will substantiate and extend our understanding of the functional roles of DGKζ in pancreatic islet cells.

Cellular expression and subcellular localization of diacylglycerol kinase γ in rat brain

“…So far 10 DGK isozymes have been identified in mammals (Goto et al 2007). Accumulating evidence has shown characteristic patterns of expression and localization of DGKs in various organs, including the central and peripheral nervous systems, heart, vascular smooth muscle and endothelial cells, lung, liver, female reproductive organs, pituitary gland, pancreas, adrenal gland, and retina under pathophysiological conditions (Goto et al 2006(Goto et al , 2007(Goto et al , 2014Nakano et al 2009Nakano et al , 2012Hozumi et al 2010Hozumi et al , 2013Hozumi et al , 2015Hozumi et al , 2016. These observations tein concentration was determined using BCA Protein Assay Reagent (Thermo Scientific, Rockford, IL).…”