Signalling to intracellular Ca2+ channels
type: CreativeWork
description: Ryanodine receptors (RyR), expressed within the ER or plasma membrane (PM), may contribute to regulated insulin secretion from pancreatic β-cells. Amplification by RyR of the Ca$^{2+}$ signals evoked by voltage-gated Ca$^{2+}$ channels may contribute to the second phase of insulin release, but the role of RyR in the plasma membrane is unresolved. My aim was to define the roles of RyR in pancreatic β-cells. I used INS-1E insulinoma cells, which have been reported to secrete insulin in response to glucose, to characterise the contribution of RyR to Ca$^{2+}$ entry and release. KCl-evoked Ca$^{2+}$ entry in INS-1E cells was mediated by L-type Ca$^{2+}$ channels. Both caffeine and carbachol evoked Ca$^{2+}$ entry and release. Caffeine-evoked Ca$^{2+}$ entry was inhibited by ryanodine and nimodipine. This might be due to direct activation of RyR in the PM, or activation of other Ca$^{2+}$-permeable channels in the PM secondary to Ca$^{2+}$ release via RyR. However, glucose did not evoke insulin secretion from INS-1E cells, and the Ca$^{2+}$ signals evoked by caffeine and carbachol became very variable with increasing passage number. It was therefore impossible with INS-1E cells to establish the role of RyR in glucose-evoked insulin release, and preliminary results with primary β-cells suggested that the quantitative analyses required to identify modest contributions from RyR would be impracticable. Previous work established that in HEK cells expressing type 1 parathyroid hormone receptors (PTH$_{1}$R), PTH(1-34) potentiated carbachol-evoked Ca$^{2+}$ release via a mechanism that required local delivery of cAMP to IP$_{3}$ receptors (IP$_{3}$R) within signalling junctions. My aim was to establish whether the interaction between adenylyl cyclase (AC) and IP$_{3}$R persists during sustained stimulation with PTH, which has been reported to cause internalization of a functional PTH$_{1}$R signalling pathway. In HEK cells expressing type 1 PTH$_{1}$R, stimulation with PTH(1-34…
abstract: Ryanodine receptors (RyR), expressed within the ER or plasma membrane (PM), may contribute to regulated insulin secretion from pancreatic β-cells. Amplification by RyR of the Ca$^{2+}$ signals evoked by voltage-gated Ca$^{2+}$ channels may contribute to the second phase of insulin release, but the role of RyR in the plasma membrane is unresolved. My aim was to define the roles of RyR in pancreatic β-cells. I used INS-1E insulinoma cells, which have been reported to secrete insulin in response to glucose, to characterise the contribution of RyR to Ca$^{2+}$ entry and release. KCl-evoked Ca$^{2+}$ entry in INS-1E cells was mediated by L-type Ca$^{2+}$ channels. Both caffeine and carbachol evoked Ca$^{2+}$ entry and release. Caffeine-evoked Ca$^{2+}$ entry was inhibited by ryanodine and nimodipine. This might be due to direct activation of RyR in the PM, or activation of other Ca$^{2+}$-permeable channels in the PM secondary to Ca$^{2+}$ release via RyR. However, glucose did not evoke insulin secretion from INS-1E cells, and the Ca$^{2+}$ signals evoked by caffeine and carbachol became very variable with increasing passage number. It was therefore impossible with INS-1E cells to establish the role of RyR in glucose-evoked insulin release, and preliminary results with primary β-cells suggested that the quantitative analyses required to identify modest contributions from RyR would be impracticable. Previous work established that in HEK cells expressing type 1 parathyroid hormone receptors (PTH$_{1}$R), PTH(1-34) potentiated carbachol-evoked Ca$^{2+}$ release via a mechanism that required local delivery of cAMP to IP$_{3}$ receptors (IP$_{3}$R) within signalling junctions. My aim was to establish whether the interaction between adenylyl cyclase (AC) and IP$_{3}$R persists during sustained stimulation with PTH, which has been reported to cause internalization of a functional PTH$_{1}$R signalling pathway. In HEK cells expressing type 1 PTH$_{1}$R, stimulation with PTH(1-34…
author: Meena, Abha
language: en
keywords: Ryanodine receptors, Insulin secretion, Ca2+ signals, Pancreatic β-cells
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/c3361aa4-8081-42bf-bc9a-bf0772bdff91/download
date published: 2015-08-18
date modified: 2026-07-22T22:24:11Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.75704