Caspase-3-induced Truncation of Type 1 Inositol Trisphosphate Receptor Accelerates Apoptotic Cell Death and Induces Inositol Trisphosphate-independent Calcium Release during Apoptosis

• Published in: The Journal of biological chemistry 2004-10, Vol.279 (41), p.43227-43236
• Main Authors: Assefa, Zerihun, Bultynck, Geert, Szlufcik, Karolina, Nadif Kasri, Nael, Vermassen, Elke, Goris, Jozef, Missiaen, Ludwig, Callewaert, Geert, Parys, Jan B, De Smedt, Humbert
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; B-Lymphocytes - metabolism; Calcium - metabolism; Calcium Channels - chemistry; Caspase 3; Caspases - metabolism; Cell Death; Cell Membrane - metabolism; Cerebellum - metabolism; Chickens; Culture Media, Serum-Free - metabolism; Cytosol - metabolism; DNA - metabolism; Enzyme Inhibitors - pharmacology; Flow Cytometry; Gene Deletion; Inositol 1,4,5-Trisphosphate - chemistry; Inositol 1,4,5-Trisphosphate Receptors; Mice; Microsomes - metabolism; Mutation; Necrosis; Protein Structure, Tertiary; Receptors, Antigen, B-Cell - metabolism; Receptors, Cytoplasmic and Nuclear - chemistry; Recombinant Proteins - chemistry; Staurosporine - pharmacology; Time Factors; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M403872200

Inositol 1,4,5-trisphosphate receptor-deficient (IP 3 RKO) B-lymphocytes were used to investigate the functional relevance of type 1 inositol 1,4,5-trisphosphate receptor (IP 3 R1) and its cleavage by caspase-3 in apoptosis. We showed that inositol 1,4,5-trisphosphate receptor-deficient cells were largely resistant to apoptosis induced by both staurosporine (STS) and B-cell receptor (BCR) stimulation. Expression of either the wild-type IP 3 R1 or an N-terminal deletion mutant (Δ1-225) that lacks inositol 1,4,5-trisphosphate-induced Ca 2+ release activity restored sensitivity to apoptosis and the consequent rise in free cytosolic Ca 2+ concentration ([Ca 2+ ] i ). Expression of caspase-3-non-cleavable mutant receptor, however, dramatically slowed down the rate of apoptosis and prevented both Ca 2+ overload and secondary necrosis. Conversely, expression of the “channel-only” domain of IP 3 R1, a fragment of the receptor generated by caspase-3 cleavage, strongly increased the propensity of the cells to undergo apoptosis. In agreement with these observations, caspase inhibitors impeded apoptosis and the associated rise in [Ca 2+ ] i . Both the staurosporine- and B-cell receptor-induced apoptosis and increase in [Ca 2+ ] i could be induced in nominally Ca 2+ -free and serum-free culture media, suggesting that the apoptosis-related rise in [Ca 2+ ] i was primarily because of the release from internal stores rather than of influx through the plasma membrane. Altogether, our results suggest that IP 3 R1 plays a pivotal role in apoptosis and that the increase in [Ca 2+ ] i during apoptosis is mainly the consequence of IP 3 R1 cleavage by caspase-3. These observations also indicate that expression of a functional IP 3 R1 per se is not enough to generate the significant levels of cytosolic Ca 2+ needed for the rapid execution of apoptosis, but a prior activation of caspase-3 and the resulting truncation of the IP 3 R1 are required.