Developmental regulation of heat shock protein synthesis and HSP 70 RNA accumulation during postimplantation rat embryogenesis.
Exposure of postimplantation rat embryos on days 9, 10, 11, and 12 of gestation to an in vitro heat shock of 43 degrees C for 30 min results in the induction of heat shock proteins (HSPs) in day 9 and 10 embryos, a severely attenuated response in day 11 embryos, and no detectable response in day 12 embryos. The heat shock response in day 9 embryos (presomite stage) is characterized by the synthesis of HSPs with molecular weights of 28-78 kDa. In heat shocked day 10 embryos, two additional HSPs are induced (34 and 82 kDa). In addition, two HSPs present on day 9 are absent on day 10. In day 11 heat shocked embryos, only three HSPs (31, 39, and 69 kDa) are induced, while in day 12 embryos no detectable HSPs are induced. Northern blot analysis of HSP 70 RNA levels indicates that the accumulation of this RNA, but not actin RNA, varies depending on developmental stage at the time of exposure to heat as well as the duration of the heat shock. Day 9 embryos exhibit the most pronounced accumulation of HSP 70 RNA while embryos on days 10-12 exhibit an increasingly attenuated accumulation of HSP 70 RNA, particularly after the more acute exposures (43 degrees C for 30 or 60 min). Thus, the ability to synthesize HSP 70 and to accumulate HSP 70 RNA changes dramatically as rat embryos develop from day 9 to day 12 (presomite to 31-35 somite stages).
Mirkes
P E
PE
Department of Pediatrics, University of Washington, Seattle 98195.
Grace
R H
RH
Little
S A
SA
D000818:Animals; D004622:Embryo, Mammalian / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006358:Hot Temperature / Q000009:adverse effects*; D008970:Molecular Weight; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D006360:Heat-Shock Proteins; D012333:RNA, Messenger