14-3-3 family members act coordinately to regulate mitotic progression.
The mitosis promoting phosphatase, cdc25C, is a target of both the DNA replication and DNA damage checkpoint pathways. These pathways regulate cdc25C function, in part, by promoting the association of cdc25C with 14-3-3 proteins, which results in the retention of cdc25C in the cytoplasm. To determine which 14-3-3 proteins were required to regulate cdc25C function, we tested the ability of various 14-3-3 family members to form a complex with and negatively regulate cdc25C in human cells. Two 14-3-3 family members, 14-3-3epsilon and 14-3-3gamma specifically formed a complex with cdc25C but not with the 14-3-3 binding defective cdc25C mutant, S216A. In addition, 14-3-3epsilon and 14-3-3gamma inhibited the ability of cdc25C, but not the S216A mutant, to induce premature chromatin condensation (PCC) in U-2OS cells. These results suggested that the reduction in PCC by 14-3-3epsilon and 14-3-3gamma was due to inhibition of cdc25C function. In contrast, 14-3-3sigma was unable to form a complex with cdc25C, but was able to inhibit the ability of both wild type cdc25C and S216A to induce PCC. This suggests that 14-3-3sigma regulates entry into mitosis independently of cdc25C and 14-3-3epsilon and 14-3-3gamma. Thus, specific members of the 14-3-3 family of proteins may act coordinately to maintain the DNA replication checkpoint by regulating the activity of different cell cycle proteins.
Dalal
Sorab N
SN
Department of Adult Oncology, Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115, USA. sdalal@@actrec.res.in
Yaffe
Michael B
MB
DeCaprio
James A
JA
D048948:14-3-3 Proteins; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008938:Mitosis / Q000502:physiology*; D005810:Multigene Family; D010802:Phylogeny; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D020687:cdc25 Phosphatases / Q000378:metabolism*
D048948:14-3-3 Proteins; D018797:Cell Cycle Proteins; D046911:Macromolecular Substances; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D014446:Tyrosine 3-Monooxygenase; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases