Abstract
We have demonstrated that a novel Ste20-related kinase, designated SLK, mediates apoptosis and actin stress fiber dissolution through distinct domains generated by caspase 3 cleavage. Overexpression of SLK in C2C12 myoblasts stimulated the disassembly of actin stress fibers and focal adhesions and induced apoptosis, as determined by annexin V binding and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling analysis. SLK was cleaved by caspase 3 in vitro and in vivo during c-Myc-, tumor necrosis factor alpha, and UV-induced apoptosis. Furthermore, cleavage of SLK released two domains with distinct activities: an activated N-terminal kinase domain that promoted apoptosis and cytoskeletal rearrangements and a C-terminus domain that disassembled actin stress fibers. Moreover, our analysis has identified a novel conserved region (termed the AT1-46 homology domain) that efficiently promotes stress fiber disassembly. Finally, transient transfection of SLK also activated the c-Jun N-terminal kinase signaling pathway. Our results suggest that caspase-activated SLK represents a novel effector of cytoskeletal remodeling and apoptosis.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actins / metabolism*
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Animals
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Apoptosis* / drug effects
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Apoptosis* / radiation effects
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Caspase 3
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Caspases / metabolism*
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Cell Adhesion
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Cell Line
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Cloning, Molecular
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Cytoskeleton / drug effects
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Cytoskeleton / metabolism
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Cytoskeleton / radiation effects
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Enzyme Activation / drug effects
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Enzyme Activation / radiation effects
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Humans
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JNK Mitogen-Activated Protein Kinases
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MAP Kinase Signaling System
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Mice
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Mitogen-Activated Protein Kinases / metabolism
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Muscles / cytology
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Muscles / enzymology
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Muscles / metabolism
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Mutation / genetics
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Protein Processing, Post-Translational / drug effects
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Protein Processing, Post-Translational / radiation effects
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Protein Serine-Threonine Kinases / chemistry*
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Protein Structure, Tertiary / genetics
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Protein Structure, Tertiary / physiology
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Proto-Oncogene Proteins c-myc / genetics
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Proto-Oncogene Proteins c-myc / physiology
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RNA, Messenger / analysis
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RNA, Messenger / genetics
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / metabolism
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Sequence Homology, Amino Acid
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Tumor Necrosis Factor-alpha / pharmacology
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Two-Hybrid System Techniques
Substances
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Actins
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Proto-Oncogene Proteins c-myc
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RNA, Messenger
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Recombinant Fusion Proteins
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Tumor Necrosis Factor-alpha
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SLK protein, human
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Protein Serine-Threonine Kinases
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SLK protein, mouse
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinases
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CASP3 protein, human
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Casp3 protein, mouse
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Caspase 3
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Caspases