Expression, synthesis, and phosphorylation of HSP28 family during development and decay of thermotolerance in CHO plateau-phase cells

✍ Scribed by Yong J. Lee; Zi-Zheng Hou; Lindali Curetty; Peter M. Corry

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 631 KB
• Volume: 150
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041500302

✦ Synopsis

We investigated a correlation between development of thermotolerance and expression, synthesis, or phosphorylation of HSP28 family in CHO plateau phase cells. After heating at 45.5"C for 10 min, thermotolerance developed rapidly and reached its maximum 12-18 hr after heat shock. This acquired thermal resistance was maintained for 72 hr and then gradually decayed. In parallel, the levels of three 28 kDa heat shock proteins, HSP28a along with its two phosphorylated isoforms (HSP28b,c), increased and reached their maximum 24-48 hr after heat shock. The levels of these polypeptides, cxcept HSP28c, remained elevated for 72 hr and then decreased. The level of HSP28 mRNA increased rapidly and reached its maximum 12 hr after heat shock. However, unlike thermotolerance and the levels of HSP28 family proteins, the level of HSP28 mRNA decreased rapidly within 72 hr. These results demonstrate a correlation between the amount of intracellular HSP28 family proteins and development and decay of thermotolerance.

MATERIALS AND METHODS

Cell culture and survival determination

Chinese hamster ovary (CHO) cells were cultured in McCoy's 5a medium (Cellgro) containing 26 mM sodium bicarbonate and 10% iron-supplemented calf serum (HyClone). For all experiments, 1 x lo5 cells were plated in T-25 flasks and grown for 4 days. At that time