CHIP chaperones wild type p53 tumor suppressor protein.
Wild type p53 exists in a constant state of equilibrium between wild type and mutant conformation and undergoes conformational changes at elevated temperature. We have demonstrated that the co-chaperone CHIP (carboxyl terminus of Hsp70-interacting protein), which suppressed aggregation of several misfolded substrates and induced the proteasomal degradation of both wild type and mutant p53, physically interacts with the amino terminus of WT53 and prevented it from irreversible thermal inactivation. CHIP preferentially binds to the p53 mutant phenotype and restored the DNA binding activity of heat-denatured p53 in an ATP-independent manner. In cells under elevated temperatures that contained a higher level of p53 mutant phenotype, CHIP restored the native-like conformation of p53 in the presence of geldanamycin, whereas CHIP-small interfering RNA considerably increased the mutant form. Further, under elevated temperatures, the levels of CHIP and p53 were higher in nucleus, and chromatin immunoprecipitation shows the presence of p53 and CHIP together upon the DNA binding site in the p21 and p53 promoters. We propose that CHIP might be a direct chaperone of wild type p53 that helps p53 in maintaining wild type conformation under physiological condition as well as help resurrect p53 mutant phenotype into a folded native state under stress condition.
School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
Veenu
V
Tripathi
School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
Amjad
A
Ali
School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
Rajiv
R
Bhat
School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India. Electronic address: uttam@mail.jnu.ac.in.
Uttam
U
Pati
D000255:Adenosine Triphosphate / Q000378:metabolism; D016227:Benzoquinones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D007624:KB Cells; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D020218:Response Elements / Q000187:drug effects / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D016227:Benzoquinones; D004791:Enzyme Inhibitors; D047029:Lactams, Macrocyclic; D018832:Molecular Chaperones; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D000255:Adenosine Triphosphate; C467728:STUB1 protein, human; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; C001277:geldanamycin