hScrib, a human homologue of Drosophila neoplastic tumor suppressor, is a novel death substrate targeted by caspase during the process of apoptosis.
hScrib, human homologue of Drosophila neoplastic tumor suppressor, was identified as a target of human papillomavirus E6 oncoprotein for the ubiquitin-mediated degradation. Here, we report that hScrib is a novel death substrate targeted by caspase. Full-length hScrib was cleaved by caspase during death ligands-induced apoptosis, which generates a p170 C-terminal fragments in Hela cells. In vitro cleavage assay using recombinant caspases showed that hScrib is cleaved by the executioner caspases. DNA damage-induced apoptosis caused loss of expression of full-length hScrib, which was recovered by addition of capase-3 inhibitor in HaCat cells. TUNEL positive apoptotic cells, which were identified 4 h after UV irradiation in HaCat cells, showed loss of hScrib expression at the adherens junction. Mutational analysis identified the caspase-dependent cleavage site of hScrib at the position of Asp-504. Although MDCK cells transfected with GFP-fused wild-type hScrib showed loss of E-cadherin expression and shrinkage of cytoplasm by UV irradiation, cells transfected with hScrib with Ala substitution of Asp-504 showed resistance to caspase-dependent cleavage of hScrib and intact expression of E-cadherin. These results indicate that caspase-dependent cleavage of hScrib is a critical step for detachment of cell contact during the process of apoptosis.
Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
Kenbun
K
Sone
Shunsuke
S
Nakagawa
Keiichi
K
Nakagawa
Shin
S
Takizawa
Yoko
Y
Matsumoto
Kazunori
K
Nagasaka
Tetsushi
T
Tsuruga
Haruko
H
Hiraike
Osamu
O
Hiraike-Wada
Yuichiro
Y
Miyamoto
Katsutoshi
K
Oda
Toshiharu
T
Yasugi
Koji
K
Kugu
Tetsu
T
Yano
Yuji
Y
Taketani
D000818:Animals; D017209:Apoptosis / Q000502:physiology* / Q000528:radiation effects; D018938:Caco-2 Cells; D020169:Caspases / Q000502:physiology*; D002450:Cell Communication / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D016923:Cell Death / Q000235:genetics / Q000528:radiation effects; D002460:Cell Line; D004249:DNA Damage / Q000502:physiology / Q000528:radiation effects; D004285:Dogs; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D018390:Gene Targeting; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D040681:Structural Homology, Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays
D029721:Drosophila Proteins; D008024:Ligands; D008565:Membrane Proteins; C480591:SCRIB protein, human; C404683:Scrib protein, Drosophila; D025521:Tumor Suppressor Proteins; D020169:Caspases