A heat shock-resistant variant of Chinese hamster cell line constitutively expressing heat shock protein of Mr 90,000 at high level.

A heat shock-resistant variant of Chinese hamster cell line (CHO) was isolated from ethane methane sulfonate-treated CHO cells through selection by repeated exposures to elevated temperature. The variant, designated HR-01, was one to two order of magnitudes more resistant to lethal heat shock (46.0 degrees C) than the parental CHO strain (p-CHO). The heat shock resistance characteristic of this variant was stable. In addition, the HR-01 variant showed more elongated cell morphology, and was more adherent to substrate than p-CHO. When total proteins of p-CHO and HR-01 cells were compared in two-dimensional polyacrylamide gel electrophoresis, HSP90, a heat shock protein of Mr 90,000, was found to be the only protein that was expressed at a significantly higher level in HR-01 cells than in p-CHO cells. Because of the known intriguing molecular properties of HSP90, the HR-01 variant would be useful for further investigation of functions of HSP90 as well as the mechanism of acquiring heat shock resistance in mammalian cells.