Induction of glucose-regulated proteins during anaerobic exposure and of heat-shock proteins after reoxygenation

Abstract

In this report we examine the effects of chronic anaerobic exposure and subsequent reoxygenation on protein synthesis patterns in Chinese hamster ovary cells. It is observed by two-dimensional gel electrophoresis (isoelectric focusing/NaDodSO4/PAGE) that the transition from an atmospheric environment to an anaerobic state transiently induces the major heat-shock proteins (at 68 and 89 kDa). As the period of anaerobiosis increases, this heat-shock induction disappears and a new set of proteins (at 76 and 97 kDa) is induced. By two-dimensional gel electrophoresis and partial proteolytic mapping, these new proteins, which are induced by anaerobic exposures exceeding 12 hr, are identical to 76 and 97 kDa (p76 and p97, respectively) proteins induced by extended periods of glucose deprivation (greater than 14 hr) when oxygen is present. Furthermore, the induction of these proteins under anoxia occurs in the presence of glucose, and increasing the glucose content of the starting media does not affect the induction. When anaerobic p76 and p97 induced cells are returned to atmospheric oxygen, p76 and p97 are repressed, while the heat-shock proteins are again transiently induced. This work further suggests the importance of deprivation and release environments in controlling the expression of these two stress protein systems. It is suggested that their natural expression may be determined by comparable circumstances.