Distribution Profile of Inositol 1, 4, 5-Trisphosphate Receptor/Ca2+ Channels in α and β Cells of Pancreas. Issue 1 (January 2015)

• Record Type: Journal Article
• Authors: Hur, Yong Suk; Yoo, Seung Hyun
• Is Part Of: Pancreas. Volume 44:Issue 1(2015)
• Publication Date: 2015-01
• Subjects: Pancreas -- Diseases -- Periodicals; Pancreas -- Periodicals; Neuroendocrine tumors -- Periodicals; 616.37005
• DOI: 10.1097/MPA.0000000000000224
• Languages: English
• ISSNs: 0885-3177

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Objectives</title> <p>The α and β cells of pancreatic islet release important hormones in response to intracellular Ca<sup>2+</sup> increases that result from Ca<sup>2+</sup> releases through the inositol 1, 4, 5-trisphoshate receptor (IP<sub>3</sub>R)/Ca<sup>2+</sup> channels. Yet no systematic studies on distribution of IP<sub>3</sub>R/Ca<sup>2+</sup> channels have been done, prompting us to investigate the distribution of all 3 IP<sub>3</sub>R isoforms.</p> </sec> <sec> <title>Methods</title> <p>Immunogold electron microscopy was performed to determine the presence and the relative concentrations of all 3 IP<sub>3</sub>R isoforms in 2 major organelles secretory granules (SGs) and the endoplasmic reticulum of α and β cells of rat pancreas.</p> </sec> <sec> <title>Results</title> <p>All 3 IP<sub>3</sub>R isoforms were present in SG membranes of both cells, and the IP<sub>3</sub>R concentrations in SGs were ∼2-fold higher than those in the endoplasmic reticulum. Moreover, large halos shown in the electron microscope images of insulin-containing SGs of β cells were gap spaces that resulted from separation of granule membranes from the surrounding cytoplasm.</p> </sec> <sec> <title>Conclusions</title> <p>These results strongly suggest the important roles of SGs in IP<sub>3</sub>-induced, Ca<sup>2+</sup>-dependent regulatory secretory pathway in pancreas. Moreover, the accurate location of SG membranes of β cells was further confirmed by the location of another integral membrane protein synaptotagmin V and of membrane phospholipid PI(4, 5)P<sub>2</sub>.</p> </sec> </abstract>