Heat shock proteins within the mammalian cell cycle: Relationship to thermal sensitivity, thermal tolerance, and cell cycle progression
✍ Scribed by Glenn Rice; Andrei Laszlo; Gloria Li; Joe Gray; William Dewey
- Publisher
- John Wiley and Sons
- Year
- 1986
- Tongue
- English
- Weight
- 734 KB
- Volume
- 126
- Category
- Article
- ISSN
- 0021-9541
No coin nor oath required. For personal study only.
✦ Synopsis
California 94550 (1. G.1 We have measured endogenous and induced rates of 70-kD, 89-kD, and 110-kD heat shock proteins in highly pure GI-, S-, or G2-M phase fractions of Chinese hamster fibroblasts (CHO) separated by fluorescence-activated cell sorting (FACS). Relative rates of synthesis of all three polypeptides as measured by two-dimensional gel electrophoresis were similar throughout the cell cycle, and therefore, endogenous levels were unlikely to explain the thermal sensitivity of S-phase cells. Distinct heterogeneity in induced rates of these polypeptides was noted in all phase fractions. Enhanced rates of 70-kD polypeptide were measured in S and G2-M as compared to GI following heat shock. Little increase in either the 89-kD or IlOk-kD heat shock proteins was observed in heated GI cells. This heterogeneity in induced rates of synthesis was in contrast to t h e similarity in thermal tolerance expression kinetics between each phase. Finally, enhanced synthesis of these polypeptides appeared unrelated to regulation of either heat-induced cell cycle delay or to t h e resumption of phase-specific progression after heat shock as measured by simultaneous flow cytometric measurement of incorporated BrdUrd and DNA content.
MATERIALS AND METHODS
Cell culture
Chinese hamster ovary cells (CHO-1OB) were cultured in McCoy's 5a modified medium (full medium) without