Ribosome-free terminals of rough ER allow formation of STIM1 puncta and segregation of STIM1 from IP3 receptors

Lur, Gyorgy, Haynes, Lee P., Prior, Ian A., Gerasimenko, Oleg Vsevolodovich ORCID: https://orcid.org/0000-0003-2573-8258, Feske, Stefan, Petersen, Ole Holger ORCID: https://orcid.org/0000-0002-6998-0380, Burgoyne, Robert D. and Tepikin, Alexei V. 2009. Ribosome-free terminals of rough ER allow formation of STIM1 puncta and segregation of STIM1 from IP3 receptors. Current Biology 19 (19) , pp. 1648-1653. 10.1016/j.cub.2009.07.072

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Abstract

Store-operated Ca2+ entry is a ubiquitous mechanism that prevents the depletion of endoplasmic reticulum (ER) calcium [1]. A reduction of ER calcium triggers translocation of STIM proteins, which serve as calcium sensors in the ER, to subplasmalemmal puncta where they interact with and activate Orai channels (2, 3, 4, 5, 6, 7 and 8; reviewed in [9]). In pancreatic acinar cells, inositol 1,4,5-trisphosphate (IP3) receptors populate the apical part of the ER. Here, however, we observe that STIM1 translocates exclusively to the lateral and basal regions following ER Ca2+ loss. This finding is paradoxical because the basal and lateral regions of the acinar cells contain rough ER (RER); the size of the ribosomes that decorate RER is larger than the distance that can be spanned by a STIM-Orai complex 5 and 10, and STIM1 function should therefore not be possible. We resolve this paradox and characterize ribosome-free terminals of the RER that form junctions between the reticulum and the plasma membrane in the basal and lateral regions of the acinar cells. Our findings indicate that different ER compartments specialize in different calcium-handling functions (Ca2+ release and Ca2+ reloading) and that any potential interference between Ca2+ release and Ca2+ influx is minimized by the spatial separation of the two processes.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences Systems Immunity Research Institute (SIURI)
Uncontrolled Keywords:	Cellbio; signaling
Publisher:	Cell Press
ISSN:	0960-9822
Last Modified:	18 Oct 2022 12:15
URI:	https://orca.cardiff.ac.uk/id/eprint/9157

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