Caspase activation of mammalian sterile 20-like kinase 3 (Mst3). Nuclear translocation and induction of apoptosis.
Mammalian Sterile 20-like kinase 3 (Mst3), the physiological functions of which are unknown, is a member of the germinal center kinase-III family. It contains a conserved kinase domain at its NH(2) terminus, whereas there is a regulatory domain at its COOH terminus. In this study we demonstrate that endogenous Mst3 is specifically cleaved when Jurkat cells were treated with anti-Fas antibody or staurosporine and that this cleavage is inhibited by the caspase inhibitor, Ac-DEVD-CHO. Using apoptotic Jurkat cell extracts and recombinant caspases, we mapped the caspase cleavage site, AETD(313), which is at the junction of the NH(2)-terminal kinase domain and the COOH-terminal regulatory domain. Caspase-mediated cleavage of Mst3 activates its intrinsic kinase activity, suggesting that the COOH-terminal domain of Mst3 negatively regulates the kinase domain. Furthermore, proteolytic removal of the Mst3 COOH-terminal domain by caspases promotes nuclear translocation. Ectopic expression of either wild-type or COOH-terminal truncated Mst3 in cells results in DNA fragmentation and morphological changes characteristic of apoptosis. By contrast, no such changes were exhibited for catalytically inactive Mst3, implicating the involvement of Mst3 kinase activity for mediation of these effects. Collectively, these results support the notion that caspase-mediated proteolytic activation of Mst3 contributes to apoptosis.
Huang
Chi-Ying F
CY
Department of Biological Science and Technology, National Chiao Tung University, 75 Po Ai Street, Hsinchu 300, Taiwan, Republic of China.
Wu
Yi-Mi
YM
Hsu
Chiung-Yueh
CY
Lee
Wan-Shu
WS
Lai
Ming-Derg
MD
Lu
Te-Jung
TJ
Huang
Chia-Lin
CL
Leu
Tzeng-Horng
TH
Shih
Hsiu-Ming
HM
Fang
Hsin-I
HI
Robinson
Dan R
DR
Kung
Hsing-Jien
HJ
Yuan
Chiun-Jye
CJ
D021581:Active Transport, Cell Nucleus; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000502:physiology*; D002467:Cell Nucleus / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D006801:Humans; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D000099317:Hippo Kinases
D020169:Caspases; D017346:Protein Serine-Threonine Kinases; C109163:STK24 protein, human; D000099317:Hippo Kinases