Thermal response in murine L929 cells lacking ?B-crystallin expression and ?B-crystallin expressing L929 transfectants

We investigated the role of αB-crystallin expression in the development of thermotolerance in murine L929 cells. An initial heat-shock of 10 min at 45°C induced thermotolerance in these cells to a heat challenge at 45°C administered 24 h later. The thermotolerance ratio at 10−1 isosurvival was 1.7. Expression of αB-crystallin gene was not detected during the 24 h incubation at 37°C following heat shock by either northern or western blots. In contrast, inducible HSP70 synthesis was observed during this time period. Thus, this cell line provided an unique system in which to examine the effects of transfected αB-crystallin on thermoresistance and thermotolerance. Cells stably transfected with αB-crystallin under the control of an inducible promoter did not show a significant increase in the ability to develop thermotolerance. However, a stably transfected L929 clone expressing high levels of constitutive αB-crystallin exhibited an approximately 50% increase in thermal resistance over parental and control cells. Though expression of αB-crystallin is not requisite for the development of thermotolerance in L929 cells, overexpression of transfected αB-crystallin can contribute to increased thermoresistance.