Apoptosis-related fragmentation, translocation, and properties of human prothymosin alpha.
Human prothymosin alpha is a proliferation-related nuclear protein undergoing caspase-mediated fragmentation in apoptotic cells. We show here that caspase-3 is the principal executor of prothymosin alpha fragmentation in vivo. In apoptotic HeLa cells as well as in vitro, caspase-3 cleaves prothymosin alpha at one major carboxy terminal (DDVD(99)) and several suboptimal sites. Prothymosin alpha cleavage at two amino-terminal sites (AAVD(6) and NGRD(31)) contributes significantly to the final pattern of prothymosin alpha fragmentation in vitro and could be detected to occur in apoptotic cells. The major caspase cleavage at D(99) disrupts the nuclear localization signal of prothymosin alpha, which leads to a profound alteration in subcellular localization of the truncated protein. By using a set of anti-prothymosin alpha monoclonal antibodies, we were able to observe nuclear escape and cell surface exposure of endogenous prothymosin alpha in apoptotic, but not in normal, cells. We demonstrate also that ectopic production of human prothymosin alpha and its mutants with nuclear or nuclear-cytoplasmic localization confers increased resistance of HeLa cells toward the tumor necrosis factor-induced apoptosis.
Evstafieva
Alexandra G
AG
Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992, Moscow, Russia
Belov
George A
GA
Rubtsov
Yuri P
YP
Kalkum
Markus
M
Joseph
Bertrand
B
Chichkova
Nina V
NV
Sukhacheva
Elena A
EA
Bogdanov
Alexey A
AA
Pettersson
Ralf F
RF
Agol
Vadim I
VI
Vartapetian
Andrey B
AB
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000595:Amino Acid Sequence / Q000502:physiology; D000911:Antibodies, Monoclonal; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D005057:Eukaryotic Cells / Q000378:metabolism*; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000378:metabolism*; D011498:Protein Precursors / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology*; D013947:Thymosin / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics
D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D011498:Protein Precursors; C040782:prothymosin alpha; D013947:Thymosin; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases