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Type 1 inositol‐1,4,5‐trisphosphate receptor is a late substrate of caspases during apoptosis
Author(s) -
Elkoreh Ghadi,
Blais Véronique,
Béliveau Éric,
Guillemette Gaétan,
Denault JeanBernard
Publication year - 2012
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.24155
Subject(s) - inositol , caspase , microbiology and biotechnology , apoptosis , receptor , substrate (aquarium) , chemistry , substrate specificity , biology , biochemistry , programmed cell death , enzyme , ecology
Apoptosis is characterized by the proteolytic cleavage of hundreds of proteins. One of them, the type 1 inositol‐1,4,5‐trisphosphate receptor (IP 3 R‐1), a multimeric receptor located on the endoplasmic reticulum (ER) membrane that is critical to calcium homeostasis, was reported to be cleaved during staurosporine (STS) induced‐apoptosis in Jurkat cells. Because the reported cleavage site separates the IP 3 binding site from the channel moiety, its cleavage would shut down a critical signaling pathway that is common to several cellular processes. Here we show that IP 3 R‐1 is not cleaved in 293 cells treated with STS, TNFα, Trail, or ultra‐violet (UV) irradiation. Further, it is not cleaved in Hela or Jurkat cells induced to undergo apoptosis with Trail, TNFα, or UV. In accordance with previous reports, we demonstrate that it is cleaved in a Jurkat cell line treated with STS. However its cleavage occurs only after poly(ADP‐ribose) polymerase (PARP), which cleavage is a hallmark of apoptosis, and p23, a poor caspase‐7 substrate, are completely cleaved, suggesting that IP 3 R‐1 is a relatively late substrate of caspases. Nevertheless, the receptor is fully accessible to proteolysis in cellulo by ectopically overexpressed caspase‐7 or by the tobacco etch virus (TEV) protease. Finally, using recombinant caspase‐3 and microsomal fractions enriched in IP 3 R‐1, we show that the receptor is a poor caspase‐3 substrate. Consequently, we conclude that IP 3 R‐1 is not a key death substrate. J. Cell. Biochem. 113: 2775–2784, 2012. © 2012 Wiley Periodicals, Inc.