A CCAAT box confers cell-type-specific regulation on the Xenopus hsp70 gene in oocytes.
The Xenopus hsp70 gene is transiently heat-inducible in somatic cells; in injected oocytes, it is efficiently expressed without heat shock. I show here that this cell-type-specific and gene-specific activation is dependent on the presence of a heat shock regulatory element (HSE) and a CCAAT box in the hsp70 promoter; neither element by itself is sufficient for full activation. The same promoter elements are also required for heat inducibility in somatic cells. I propose that CAAT-binding transcription factor (CTF) interacts with heat shock transcription factor (HSTF), thereby enhancing the affinity of HSTF for the promoter; cell-type specificity could be explained by assuming either oocyte-specific forms or oocyte-specific high levels of CTF and/or HSTF.
D000818:Animals; D004274:DNA, Recombinant; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000235:genetics*; D009865:Oocytes / Q000502:physiology*; D011401:Promoter Regions, Genetic; D013937:Thymidine Kinase / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014982:Xenopus laevis / Q000235:genetics*
D004274:DNA, Recombinant; D006360:Heat-Shock Proteins; D014157:Transcription Factors; D013937:Thymidine Kinase