Stress response genes are suppressed in mouse preimplantation embryos by granulocyte-macrophage colony-stimulating factor (GM-CSF).
BACKGROUND
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known to promote the development and survival of human and mouse preimplantation embryos; however, the mechanism of action of GM-CSF in embryos is not defined.


METHODS
Mouse blastocysts were cultured from zygote stage in vitro with and without recombinant mouse GM-CSF (rmGM-CSF), and in vivo developed blastocysts were flushed from Csf2 null mutant and wild-type mice. The effect of GM-CSF on blastocyst expression of stress response and apoptosis genes was evaluated by microarray, qPCR and immunochemistry.


RESULTS
Microarray analysis of the gene transcription profile showed suppression of stress response and apoptosis gene pathways in blastocysts exposed to rmGM-CSF in vitro. qPCR analysis confirmed that rmGM-CSF inhibited expression of heat shock protein (HSP) and apoptosis pathway genes Cbl, Hspa5, Hsp90aa1, Hsp90ab1 and Gas5 in in vitro blastocysts. Immunocytochemical analysis of HSP 1 (HSPA1A/1B; HSP70), BAX, BCL2 and TRP53 (p53) in in vitro blastocysts showed that HSPA1A/1B and BCL2 proteins were less abundant when embryos were cultured with rmGM-CSF. BAX and TRP53 were unchanged at the protein level, but Bax mRNA expression was reduced after GM-CSF treatment. In in vivo developed blastocysts, Csf2 null mutation caused elevated expression of Hsph1 but not other stress response genes.


CONCLUSIONS
We conclude that GM-CSF inhibits the cellular stress response and apoptosis pathways to facilitate embryo growth and survival, and the protective effects of GM-CSF are particularly evident in in vitro culture media, whereas in vivo other cytokines can partly compensate for absence of GM-CSF.
Chin
Peck Y
PY
Research Centre for Reproductive Health, Discipline of Obstetrics and Gynaecology, University of Adelaide, Adelaide, SA 5005, Australia.
Macpherson
Anne M
AM
Thompson
Jeremy G
JG
Lane
Michelle
M
Robertson
Sarah A
SA
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001755:Blastocyst / Q000378:metabolism* / Q000473:pathology; D004624:Embryo Transfer / Q000379:methods; D047108:Embryonic Development; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008856:Microscopy, Fluorescence; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013312:Stress, Physiological / Q000235:genetics*
D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; C000717248:Hspa5 protein, mouse; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor