Cleavage of MAGI-1, a tight junction PDZ protein, by caspases is an important step for cell-cell detachment in apoptosis.
MAGI-1, a member of the MAGUK family of proteins, is shown to be rapidly cleaved during Fas-induced apoptosis in mouse 3T3 A31 cells, and in UV irradiation- and staurosporine-induced apoptosis in HaCaT cells. This generates a 97 kDa N-terminal fragment that dissociates from the cell membrane; a process that is largely prevented in the presence of the caspase inhibitor Z-VAD-fmk. In addition, we show that in vitro translated radiolabelled MAGI-1 is efficiently cleaved into 97 kDa and 68 kDa fragments by caspases-3 and -7 at physiological concentrations and mutating the MAGI-1 Asp(761) to Ala completely abolished the caspase-induced cleavage. Moreover, in HaCaT cells overexpressing the MAGI-1 Asp(761)Ala mutant the disruption of cell-cell contacts was delayed during apoptosis, whereas other caspase-dependent processes such as nuclear condensation were not affected, suggesting that cell detachment is parallel to them. Thus, MAGI-1 cleavage appears to be an important step in the disassembly of cell-cell contacts during apoptosis.
Gregorc
Uros
U
Department of Biochemistry and Molecular Biology, J. Stefan Institute, Ljubljana, Slovenia.
Ivanova
Saska
S
Thomas
Miranda
M
Guccione
Ernesto
E
Glaunsinger
Britt
B
Javier
Ron
R
Turk
Vito
V
Banks
Lawrence
L
Turk
Boris
B
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D015820:Cadherins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D015815:Cell Adhesion Molecules; D015816:Cell Adhesion Molecules, Neuronal; D002450:Cell Communication; D051528:Guanylate Kinases; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000528:radiation effects; D021381:Protein Transport / Q000187:drug effects / Q000528:radiation effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays; D019014:fas Receptor / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D015820:Cadherins; D015815:Cell Adhesion Molecules; D015816:Cell Adhesion Molecules, Neuronal; C491899:Fas protein, mouse; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D019014:fas Receptor; D051528:Guanylate Kinases; C113338:MAGI1 protein, human; C493280:Magi1 protein, mouse; D020169:Caspases; D019311:Staurosporine