Spontaneous high expression of heat-shock proteins in mouse embryonal carcinoma cells and ectoderm from day 8 mouse embryo.

Abstract

When submitted to a heat-shock, mouse embryonal carcinoma (EC) and fibroblast cells show very different behavior. AN the EC cells so far analyzed express very high levels of several heat-shock proteins (HSP) in the absence of stress and independent of their origin and culture conditions. In such cells, the 89-kd, 70-kd and 59-kd HSP are the most prominent proteins after actin. In addition, the 89-kd and 59-kd HSP are not stimulated by an arsenite shock in contrast to what is observed with fibroblasts or cells of the parietal yolk sac type. Arsenite induces the synthesis of a 105-kd polypeptide in fibroblasts but not in EC cells. In vitro differentiation of F9 cells induced by retinoic acid and dibutyryl cAMP is accompanied by a decrease in the spontaneous relative abundance of HSP and restores the arsenite-induced synthesis of the 105-kd polypeptide. EC cells are usually believed to be similar to inner cell mass cells of mouse blastocyst. Furthermore, data in the literature together with our own results suggest that the same three HSP are also spontaneously expressed in high amounts in the early mouse embryo.

Nonexpression of a major heat shock gene in mouse plasmacytoma MPC-11.

“…In our experience and in that of others (5,12,24,25), mouse cells respond to a 44°C, 10-to 20-min heat shock by synthesis of a limited number of heat shock proteins. The most prominent is a 68,000-dalton * Corresponding author.…”

“…Densitometric scanning of the autoradiograph indicated an approximately fivefold increase in expression of the 70-kDa protein and two-to threefold increases of the 89-and 74-kDa bands at 43°C. Proteins of these sizes have been identified previously as heat shock products in mammalian cells (5,15,16,22,24,25). In melanogaster, it is thought that at least one protein interacts with the heat shock regulatory region located upstream from the 5' end of the heat shock genes (29,38,39).…”

Recognition and killing of tumour cells expressing heat shock protein 65 kD with immunotoxins containing saporin

“…In Hela cells, HSP70 interacts with other cellular proteins in a cell cycle-dependent manner; synthesis of HSP has been shown to increase during mitosis (Pechan, 1991). Other HSP such as HSP90 and HSP70 have been found to reach abnormally high levels in transformed cells (Bensaude & Morange, 1983). Proteins belonging to the HSP70 family were shown to interact with nuclear oncogenes such as p53, and the stability of this interaction might influence transformation (Finlay et al, 1988 …”

Two specific markers for neural differentiation of embryonal carcinoma cells.

“…A group of 89 K proteins (HS89) known to be induced by heat-shock in other systems (Bensaude and Morange, 1983) is synthesized at a much lower rate after differentiation.…”