title: Degradation of the type I inositol 1,4,5-trisphosphate receptor by caspase-3 in SH-SY5Y neuroblastoma cells undergoing apoptosis.
abstract: The type I inositol 1,4,5-trisphosphate (IP(3)) receptor is selectively down-regulated in several neurodegenerative diseases, including Alzheimer's disease, Huntington's chorea, and ischemia, all conditions in which apoptotic neuronal loss occurs. In the present study, we used a neuronal cell line, human neuroblastoma SH-SY5Y cells, to investigate whether the levels of IP(3) receptor are changed during apoptosis in these cells. Following induction of apoptosis by staurosporine, the immunoreactivity of the type I IP(3) receptor in microsome preparations from SH-SY5Y cells was reduced within 2 h, with a further reduction during subsequent hours. Immunoblot analyses, using antibodies to poly(ADP-ribose) polymerase and spectrin breakdown products, revealed proteolysis of these caspase-3 substrates within 3 h, confirming that IP(3) receptor cleavage is an early consequence of apoptosis. In vitro incubation of SH-SY5Y microsomes or immunopurified IP(3) receptor from rat cerebellum with recombinant caspase-3 led to generation of immunoreactive breakdown products similar to those observed in intact cells, suggesting that the type I IP(3) receptor is a potential substrate for caspase-3. Preincubation of the neuroblastoma cells with the caspase-3 inhibitor Z-Asp-Glu-Val-Asp-fluoromethyl ketone prevented IP(3) receptor degradation. These results show that the type I IP(3) receptor is a substrate for caspase-3 in neuronal cells and indicate that apoptotic down-regulation of IP(3) receptor levels may contribute to the pathology of neurodegenerative conditions.
authors.affiliation: Neurochemical Laboratory, University of Oslo, Oslo, Norway.
authors.forename: L S
authors.initials: LS
authors.lastname: Haug
authors.forename: S I
authors.initials: SI
authors.lastname: Walaas
authors.forename: A C
authors.initials: AC
authors.lastname: Ostvold
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D017209:Apoptosis; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D019311:Staurosporine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D015220:Calcium Channels; D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009842:Oligopeptides; D018160:Receptors, Cytoplasmic and Nuclear; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D019311:Staurosporine