Targeted proteomic analysis of 14-3-3 sigma, a p53 effector commonly silenced in cancer.
To comprehensively identify proteins interacting with 14-3-3 sigma in vivo, tandem affinity purification and the multidimensional protein identification technology were combined to characterize 117 proteins associated with 14-3-3 sigma in human cells. The majority of identified proteins contained one or several phosphorylatable 14-3-3-binding sites indicating a potential direct interaction with 14-3-3 sigma. 25 proteins were not previously assigned to any function and were named SIP2-26 (for 14-3-3 sigma-interacting protein). Among the 92 interactors with known function were a number of proteins previously implicated in oncogenic signaling (APC, A-RAF, B-RAF, and c-RAF) and cell cycle regulation (AJUBA, c-TAK, PTOV-1, and WEE1). The largest functional classes comprised proteins involved in the regulation of cytoskeletal dynamics, polarity, adhesion, mitogenic signaling, and motility. Accordingly ectopic 14-3-3 sigma expression prevented cellular migration in a wounding assay and enhanced mitogen-activated protein kinase signaling. The functional diversity of the identified proteins indicates that induction of 14-3-3 sigma could allow p53 to affect numerous processes in addition to the previously characterized inhibitory effect on G2/M progression. The data suggest that the cancer-specific loss of 14-3-3 sigma expression by epigenetic silencing or p53 mutations contributes to cancer formation by multiple routes.
Benzinger
Anne
A
Molecular Oncology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried/Munich, Germany.
Muster
Nemone
N
Koch
Heike B
HB
Yates
John R
JR
Hermeking
Heiko
H
D048948:14-3-3 Proteins / Q000172:deficiency* / Q000235:genetics; D002453:Cell Cycle; D049109:Cell Proliferation; D002478:Cells, Cultured; D020868:Gene Silencing; D006801:Humans; D007668:Kidney / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
D048948:14-3-3 Proteins; D016159:Tumor Suppressor Protein p53