Heat shock resistance conferred by expression of the human HSP27 gene in rodent cells.

Abstract

Abstract. Heat shock induces in cells the synthesis of specific proteins called heat shock proteins (HSPs) and a transient state of thermotolerance. The putative role of one of the HSPs, HSP27, as a protective molecule during thermal stress has been directly assessed by measuring the resistance to hyperthermia of Chinese hamster and mouse cells transfected with the human HSP27 gene contained in plasmid pHS2711. One-and two-dimensional gel electrophoresis of [3H]leucineand [32P]orthophosphate-labeled proteins, coupled with immunological analysis using Ha27Ab and Hu27Ab, two rabbit antisera that specifically recognize the hamster and the human HSP27 protein respectively, were used to monitor expression and inducibility of the transfected and endogenous proteins. The human HSP27 gene cloned in pHS2711 is constitutively expressed in rodent cells, resulting in accumulation of the human HSP27 and all phosphorylated derivatives. No modification of the basal or heat-induced expression of endogenous HSPs is detected. The presence of additional HSP27 protein provides immediate protection against heat shock administered 48 h after transfection and confers a permanent thermoresistant phenotype to stable transfectant Chinese hamster and mouse cell lines. Mild heat treatment of the transfected cells results in an induction of the full complement of the endogenous heat shock proteins and a small increase in thermoresistance, but the level attained did not surpass that of heat-induced thermotolerant control cells. These results indicate that elevated levels of HSP27 is sufficient to give protection from thermal killing. It is concluded that HSP27 plays a major role in the increased thermal resistance acquired by cells after exposure to HSP inducers.

Hsp27 functions as a negative regulator of cytochrome c-dependent activation of procaspase-3

“…Expression of Hsp27 had no detectable e ect on the levels of other heat-shock protein, Hsp70 (Landry et al, 1989). Cyt c-dependent activation of cas-3 was then analysed after addition of cyt c/dATP.…”

A potential role of heat shock proteins and nicotinamide N‐methyl transferase in predicting response to radiation in bladder cancer

“…10 Several studies have shown that overexpression of HSP27 is linked to resistance to heat shock and to a variety of chemotherapeutic drugs in different cell types [11][12][13] but not to radiation. 14 HSP27 was found to be downregulated in the radiosensitive cell line, which suggests a possible role of HSP27 in determining radioresistance.…”

Implication of Bcl-2 family genes in basal and d-amphetamine-induced apoptosis in preneoplastic and neoplastic rat liver lesions

“…sis in in vitro cultured cells. [28][29][30][31][32][33][34]62 Thus, the opposite behavior of AI and Hsp27 levels, in normal liver and N12, with the highest AI in correspondence with the lowest Hsp27 level, and peak Hsp27 values in correspondence with low AI, suggests that Hsp27 may contribute, together with recovery of the expression of antiapoptotic genes of Bcl-2 family, to the decrease in apoptosis in these tissues after the peak value at 4 hours. A different situation seems to exist in atypical liver lesions, which exhibit persistent apoptosis even in the presence of relatively high Hsp27 levels (i.e., at 18 hours).…”