TY - JOUR
T1 - Herp stabilizes neuronal Ca2+ homeostasis and mitochondrial function during endoplasmic reticulum stress
AU - Chan, Sic L.
AU - Fu, Weiming
AU - Zhang, Peisu
AU - Cheng, Aiwu
AU - Lee, Jaewon
AU - Kokame, Koichi
AU - Mattson, Mark P.
PY - 2004/7/2
Y1 - 2004/7/2
N2 - In response to endoplasmic reticulum (ER) stress, cells launch homeostatic and protective responses, but can also activate cell death cascades. A 54 kDa integral ER membrane protein called Herp was identified as a stress-responsive protein in non-neuronal cells. We report that Herp is present in neurons in the developing and adult brain, and that it is regulated in neurons by ER stress; sublethal levels of ER stress increase Herp levels, whereas higher doses decrease Herp levels and induce apoptosis. The decrease in Herp protein levels following a lethal ER stress occurs prior to mitochondrial dysfunction and cell death, and is mediated by caspases which generate a 30-kDa proteolytic Herp fragment. Mutagenesis of the caspase cleavage site in Herp enhances its neuroprotective function during ER stress. While suppression of Herp induction by RNA interference sensitizes neural cells to apoptosis induced by ER stress, overexpression of Herp promotes survival by a mechanism involving stabilization of ER Ca2+ levels, preservation of mitochondrial function and suppression of caspase 3 activation. ER stress-induced activation of JNK/c-Jun and caspase 12 are reduced by Herp, whereas induction of major ER chaperones is unaffected. Herp prevents ER Ca2+ overload under conditions of ER stress and agonist-induced ER Ca2+ release is attenuated by Herp suggesting a role for Herp in regulating neuronal Ca2+ signaling. By stabilizing ER Ca2+ homeostasis and mitochondrial functions, Herp serves a neuroprotective function under conditions of ER stress.
AB - In response to endoplasmic reticulum (ER) stress, cells launch homeostatic and protective responses, but can also activate cell death cascades. A 54 kDa integral ER membrane protein called Herp was identified as a stress-responsive protein in non-neuronal cells. We report that Herp is present in neurons in the developing and adult brain, and that it is regulated in neurons by ER stress; sublethal levels of ER stress increase Herp levels, whereas higher doses decrease Herp levels and induce apoptosis. The decrease in Herp protein levels following a lethal ER stress occurs prior to mitochondrial dysfunction and cell death, and is mediated by caspases which generate a 30-kDa proteolytic Herp fragment. Mutagenesis of the caspase cleavage site in Herp enhances its neuroprotective function during ER stress. While suppression of Herp induction by RNA interference sensitizes neural cells to apoptosis induced by ER stress, overexpression of Herp promotes survival by a mechanism involving stabilization of ER Ca2+ levels, preservation of mitochondrial function and suppression of caspase 3 activation. ER stress-induced activation of JNK/c-Jun and caspase 12 are reduced by Herp, whereas induction of major ER chaperones is unaffected. Herp prevents ER Ca2+ overload under conditions of ER stress and agonist-induced ER Ca2+ release is attenuated by Herp suggesting a role for Herp in regulating neuronal Ca2+ signaling. By stabilizing ER Ca2+ homeostasis and mitochondrial functions, Herp serves a neuroprotective function under conditions of ER stress.
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U2 - 10.1074/jbc.M404272200
DO - 10.1074/jbc.M404272200
M3 - Article
C2 - 15102845
AN - SCOPUS:3142545254
SN - 0021-9258
VL - 279
SP - 28733
EP - 28743
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 27
ER -