The cellular response to toxic stimuli is elicited through the expression of heat shock proteins, a transcriptional process that relies upon conserved DNA elements in the promoters: the Heat Shock Elements, activated by the heat shock factors, and the CCAAT boxes. The identity of the CCAAT activator(s) is unclear because two distinct entities, NF-Y and HSP-CBF, have been implicated in the HSP70 system, The former is a conserved ubiquitous trimer containing histone-like subunits, the latter a 110-kDa protein with an acidic N-terminal, We analyzed two CCAAT-containing promoters, HSP70 and HSP40, with recombinant NF-Y and HSP-CBF using electrophoretic mobility shift assay, protein-protein interactions, transfections and chromatin immunoprecipitation assays (ChIP) assays. Both recognize a common DNA-binding protein in nuclear extracts, identified in vitro and in vivo as NF-Y, Both CCAAT boxes show high affinity for recombinant NF-Y but not for HSP-CBF, However, HSP-CBF does activate HSP70 and HSP40 transcription under basal and heat shocked conditions; for doing so, it requires an intact NF-Y trimer as judged by cotransfections with a diagnostic NF-YA dominant negative vector. HSP-CBF interacts in solution and on DNA with the NF-Y trimer through an evolutionary conserved region. In yeast two-hybrid assays HSP-CBF interacts with NF-YB, These data implicate HSP-CBF as a non-DNA binding coactivator of heat shock genes that act on a DNA-bound NF-Y.
|Data di pubblicazione:||2001|
|Titolo:||HSP-CBF is an NF-Y-dependent coactivator of the heat shock promoters CCAAT boxes|
|Autore/i:||Imbriano, Carol; F., Bolognese; A., Gurtner; G., Piaggio; Mantovani, Roberto|
|Digital Object Identifier (DOI):||10.1074/jbc.M101553200|
|Codice identificativo ISI:||WOS:000169823300092|
|Codice identificativo Scopus:||2-s2.0-0035854652|
|Tipologia||Articolo su rivista|
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