| HSP90 is one of the important members in heat shock protein family. Served as specific molecular chaperone, HSP90 participates in the regulation of kinases activity in many signal transduction pathways, nuclear receptor family and transcription factor p53 et al, and plays an important biological role in cell growth, development, differentiation; protein synthesis, folding, transportation, degradation; the function of cell skeleton and membrane as well as protections of cells from various kind of injury when they were exposed to stress conditions. hsp90 gene is one of the minor members that contain introns in heat shock protein gene family . Human hsp90 gene consists of two copies: α and β. Our research group have been studying the expression and regulation of hsp90α and hsp90β since 1985. We found that the expression and regulation of hsp90 is mainly on transcription level, and is complex, with many factors involved in. The study on its regulation mechanism will not only lead to a better understanding of its biological functions, but also can establish a good model for regulation mechanism of induced eukaryotic gene expression. Although they are highly homologous ( at 86% ) at the protein level, the two copies of hsp90 gene are regulated differently at the transcription level, and have different expression kinetics in Jurkat cell. HSP90β may play a dominant role in the specific chaperone function of HSP90. We had reported that in Jurkat cells, the first intron is critical for heat shock inducibility of human hsp90β gene. An AT-rich region (~70% AT.) located in the 3' of the first intron cooperates with the core promoter located in the 5' flanking sequence is necessary in maintaining high constitutive expression. The inducible transcription driven by the first intron of hsp90β gene was mainly regulated by cellular HSF1. Atypical HSE in the 5' flanking sequence of hsp90 β gene was not efficient enough to respond to an elevated...
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