title: Caspase-mediated cleavage of the Ca2+/calmodulin-dependent protein kinase-like kinase facilitates neuronal apoptosis.
abstract: This study was designed to identify the role of a recently identified Ca(2+)/calmodulin-dependent protein kinase (CaMK)-like kinase (CaMKLK) in neuronal apoptosis. For this purpose, we studied proteolytic cleavage of CaMKLK by caspases in vitro and in neuronal NG108 cells. In addition, we have investigated the effect of overexpression of wild type and mutant CaMKLK proteins on staurosporine- and serum deprivation-induced apoptosis of NG108 cells. We found that CaMKLK is a substrate for caspase-3 and -8, both in vitro and in NG108 cells during staurosporine- and serum withdrawal-induced apoptosis. Substitution of an aspartic acid residue at position 62 in an asparagine residue within a putative caspase cleavage site completely blocked cleavage of CaMKLK, strongly indicating that (59)DEND(62) is the caspase recognition site. Overexpression of an Asp(62) --> Asn CaMKLK mutant protected NG108 cells from staurosporine-induced apoptosis to a similar extent as Bcl-x(L). In contrast, overexpression of wild type CaMKLK did not lead to protection. Moreover, microinjection of Asp(62) --> Asn CaMKLK protected NG108 cells from serum deprivation-induced apoptosis, while overexpression of a caspase-generated noncatalytic N-terminal CaMKLK fragment exacerbated apoptosis. Together, our data suggest that cleavage of CaMKLK and generation of the noncatalytic N-terminal domain of CaMKLK facilitate neuronal apoptosis.
authors.affiliation: Division of Medical Pharmacology, Leiden/Amsterdam Center for Drug Research/Leiden University Medical Center, Leiden University, P.O. Box 9503, 2300 RA, Leiden, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Kruidering
authors.forename: T
authors.initials: T
authors.lastname: Schouten
authors.forename: G I
authors.initials: GI
authors.lastname: Evan
authors.forename: E
authors.initials: E
authors.lastname: Vreugdenhil
mesh_terms: D000818:Animals; D017209:Apoptosis; D001216:Asparagine / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D009474:Neurons / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019311:Staurosporine / Q000494:pharmacology; D013347:Subcellular Fractions; D014407:Tumor Cells, Cultured
chemical_list: D002147:Calmodulin; D016895:Culture Media, Serum-Free; D018076:DNA, Complementary; D011500:Protein Synthesis Inhibitors; D001224:Aspartic Acid; D001216:Asparagine; D004247:DNA; C517596:CAMK1 protein, human; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D019311:Staurosporine; D002118:Calcium