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SERCA pump activity is physiologically regulated by presenilin and regulates amyloid β production
Correspondence to Frank M. LaFerla: laferla{at}uci.edu
In addition to disrupting the regulated intramembraneous proteolysis of key substrates, mutations in the presenilins also alter calcium homeostasis, but the mechanism linking presenilins and calcium regulation is unresolved. At rest, cytosolic Ca2+ is maintained at low levels by pumping Ca2+ into stores in the endoplasmic reticulum (ER) via the sarco ER Ca2+-ATPase (SERCA) pumps. We show that SERCA activity is diminished in fibroblasts lacking both PS1 and PS2 genes, despite elevated SERCA2b steady-state levels, and we show that presenilins and SERCA physically interact. Enhancing presenilin levels in Xenopus laevis oocytes accelerates clearance of cytosolic Ca2+, whereas higher levels of SERCA2b phenocopy PS1 overexpression, accelerating Ca2+ clearance and exaggerating inositol 1,4,5-trisphosphate–mediated Ca2+ liberation. The critical role that SERCA2b plays in the pathogenesis of Alzheimer's disease is underscored by our findings that modulating SERCA activity alters amyloid β production. Our results point to a physiological role for the presenilins in Ca2+ signaling via regulation of the SERCA pump.
Abbreviations used in this paper: Aβ, amyloid β; AD, Alzheimer's disease; AICD, APP intracellular domain; APP, amyloid precursor protein; CCE, capacitative Ca2+ entrance; FAD, familial AD; IP3, inositol 1,4,5-trisphosphate; MEF, mouse embryonic fibroblast; nAChR, nicotinic acetylcholine receptor; pcDNA, pseudo-cDNA; PSDKO, presenilin double knockout; SERCA, sarco ER Ca2+-ATPase.
© 2008 Green et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
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