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Ubiquitination of DAPK is essential for its stability and function
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.648.2
Subject(s) - ubiquitin , microbiology and biotechnology , immunoprecipitation , proteasome , phosphorylation , kinase , apoptosis , chemistry , protein kinase a , hsp90 , mapk/erk pathway , heat shock protein , biology , cell culture , biochemistry , gene , genetics
Ubiquitination regulates a host of critical cellular functions including apoptosis, frequently by mediating the degradation of master regulatory proteins by proteasomes. Death associated protein kinase (DAPK) is a Ca2+/calmodulin (CaM)‐regulated Ser/Thr kinase and has been shown to have important role in cell death and survival. Recent studies have shown that the activity of DAPK as well is tightly regulated by an unusual auto‐phosphorylation mechanism. The goal of these studies is to identify and characterize additional mechanisms by which DAPK activities are modulated in cells. Identification of binding proteins using yeast 2‐hybrid studies and co‐immunoprecipitation has revealed that DAPK binds a number of cellular proteins including two distinct ubiquitin ligases, mind bomb (mib1) and CHIP, HSP90, and TNFR1. Analysis of the cellular levels and activity of DAPK in response to altering the expression of these proteins revealed that DAPK is stabilized by HSP90 and that ubiquitination by CHIP occurs on inactive DAPK while activated DAPK is targeted for proteasomal degradation by mib1. In addition, altering the cellular levels of DAPK has profound effects on TNF‐mediated induction of apoptosis and cell viability. Together these results suggest that the cellular levels of DAPK are regulated by proteasomal degradation and that DAPK has a central role in signaling pathways emanating from the TNF receptor.