Short 42 degrees C heat shock induces phosphorylation and degradation of Cdc25A which depends on p38MAPK, Chk2 and 14.3.3.
The effects of heat shock (HS; 42 degrees C) on the cell cycle and underlying molecular mechanisms are astonishingly unexplored. Here, we show that HS caused rapid Cdc25A degradation and a reduction of cell cycle progression. Cdc25A degradation depended on Ser75-Cdc25A phosphorylation caused by p38MAPK and Chk2, which phosphorylated Ser177-Cdc25A that is specific for 14.3.3 binding. Upon HS, Cdc25A rapidly co-localized with 14.3.3 in the perinuclear space that was accompanied with a decrease of nuclear Cdc25A protein levels. Consistently, a 14.3.3 binding-deficient Cdc25A double mutant (Ser177/Ala-Tyr507/Ala) was not degraded in response to HS and there was no evidence for an increased co-localization of Cdc25A with 14.3.3 in the cytosol. Therefore, upon HS, p38, Chk2 and 14.3.3 were antagonists of Cdc25A stability. On the other hand, Cdc25A was protected by Hsp90 in HEK293 cells because the specific inhibition of Hsp90 with Geldanamycin caused Cdc25A degradation in HEK293 implicating that Cdc25A is an Hsp90 client. Specific inhibition of Hsp90 together with HS caused and accelerated degradation of Cdc25A and was highly cytotoxic. The results presented here show for the first time that Cdc25A is degraded by moderate heat shock and protected by Hsp90. We describe the mechanisms explaining HS-induced cell cycle retardation and provide a rationale for a targeted hyperthermia cancer therapy.
Madlener
Sibylle
S
Institute of Clinical Pathology, Medical University of Vienna, Austria.
Rosner
Margit
M
Krieger
Sigurd
S
Giessrigl
Benedikt
B
Gridling
Manuela
M
Vo
Thanh Phuong Nha
TP
Leisser
Christina
C
Lackner
Andreas
A
Raab
Ingrid
I
Grusch
Michael
M
Hengstschläger
Markus
M
Dolznig
Helmut
H
Krupitza
Georg
G
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002466:Cell Nucleolus / Q000235:genetics / Q000378:metabolism; D064447:Checkpoint Kinase 2; D003600:Cytosol / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D020687:cdc25 Phosphatases / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
D048948:14-3-3 Proteins; D018841:HSP90 Heat-Shock Proteins; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020687:cdc25 Phosphatases