The ryanodine receptor calcium channel of beta-cells: molecular regulation and physiological significance
2002 (English)In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 51, no 5, 1299-1309 p.Article in journal (Refereed) Published
The list of Ca(2+) channels involved in stimulus-secretion coupling in beta-cells is increasing. In this respect the roles of the voltage-gated Ca(2+) channels and IP(3) receptors are well accepted. There is a lack of consensus about the significance of a third group of Ca(2+) channels called ryanodine (RY) receptors. These are large conduits located on Ca(2+) storage organelle. Ca(2+) gates these channels in a concentration- and time-dependent manner. Activation of these channels by Ca(2+) leads to fast release of Ca(2+) from the stores, a process called Ca(2+)-induced Ca(2+) release (CICR). A substantial body of evidence confirms that beta-cells have RY receptors. CICR by RY receptors amplifies Ca(2+) signals. Some properties of RY receptors ensure that this amplification process is engaged in a context-dependent manner. Several endogenous molecules and processes that modulate RY receptors determine the appropriate context. Among these are several glycolytic intermediates, long-chain acyl CoA, ATP, cAMP, cADPR, NO, and high luminal Ca(2+) concentration, and all of these have been shown to sensitize RY receptors to the trigger action of Ca(2+). RY receptors, thus, detect co-incident signals and integrate them. These Ca(2+) channels are targets for the action of cAMP-linked incretin hormones that stimulate glucose-dependent insulin secretion. In beta-cells some RY receptors are located on the secretory vesicles. Thus, despite their low abundance, RY receptors are emerging as distinct players in beta-cell function by virtue of their large conductance, strategic locations, and their ability to amplify Ca(2+) signals in a context-dependent manner.
Place, publisher, year, edition, pages
2002. Vol. 51, no 5, 1299-1309 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-132283PubMedID: 11978625OAI: oai:DiVA.org:uu-132283DiVA: diva2:357455