HSFs and regulation of Hsp70.1 (Hspa1b) in oocytes and preimplantation embryos: new insights brought by transgenic and knockout mouse models.
Gene encoding heat shock protein (Hsps) are induced following a thermal stress thanks to the activation of heat shock transcription factor (HSF) which interacts with heat shock elements (HSE) located within the sequence of Hsp promoters. This cellular and protective response (heat shock response (HSR)) is well known and evolutionarily conserved. Nevertheless, HSR does not function in all the cells produced during the life of a multicellular organism, e.g., early mouse embryos. Taking advantage of mouse transgenic and knockout models, we investigated the roles of trans (HSF 1 and 2) and cis (HSE) regulatory elements in the control of Hsp70.1 (Hspa1b) through several developmental steps from oocytes to blastocysts. Our studies confirm that, even in absence of any stress, HSF1 regulates Hsp70.1 in oocytes and early embryos. Our data emphasize the role of maternal and paternal HSFs in the developmentally regulated expression of Hsp70.1 observed when the zygotic genome activation occurs. Furthermore, in this unstressed developmental condition, affinity and binding to HSEs might be more permissive than in the stress response. Finally, submitting blastocyst to different stress conditions, we show that HSF2 is differentially required for Hsp expression and cell survival. Taken together, our findings indicate that the role of heat shock trans and cis regulatory elements evolve along the successive steps of early embryonic development.
Université Toulouse 3, UPS, UMR 5547, Centre de Biologie du Développement, 118 route de Narbonne (Bat 4R3B3), Toulouse Cedex 09, France.
Florent
F
Le Masson
Elisabeth
E
Christians
D000818:Animals; D001483:Base Sequence; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism*; D049109:Cell Proliferation; D002470:Cell Survival; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D017354:Point Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D013312:Stress, Physiological / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015053:Zygote / Q000166:cytology / Q000378:metabolism
D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C490017:Hsf1 protein, mouse; C531390:Hsf2 protein, mouse; D014157:Transcription Factors; C081884:heat-shock protein 70.1; D008156:Luciferases