title: Short-Term culture of in vitro produced bovine preimplantation embryos with insulin-like growth factor-i prevents heat shock-induced apoptosis through activation of the Phosphatidylinositol 3-Kinase/Akt pathway.
abstract: Insulin-like growth factor (IGF-I) has been implicated as a thermoprotective molecule for the preimplantation bovine embryo. Here, it was shown that effects of heat shock (41 degrees C for 15 hr) on induction of apoptosis and reduction in cell number in bovine embryos collected at Day 5 after fertilization were blocked by addition of 100 ng/ml IGF-I at the initiation of heat shock. This action of IGF-I to block heat shock-induced apoptosis was eliminated if embryos were cultured with either a phosphatidylinositol 3-kinase (PI3K) inhibitor (wortmannin) or an Akt inhibitor (1L-6-hydroxymethyl-chiro-inositol 2-(R)-2-o-methyl-3-o-octadecylcarbonate). Immunofluorescence microscopy confirmed the expression of phosphorylated Akt for IGF-I and control embryos. Immunoblotting using an antibody to Akt (phospho S473) indicated increased phosphorylation of Akt in IGF-I-treated embryos. In conclusion, short-term treatment of embryos with IGF-I can block induction of apoptosis caused by heat shock through signaling events requiring PI3K and Akt.
authors.affiliation: Department of Animal Sciences, University of Florida, Gainesville, Florida, USA.
authors.forename: F Dean
authors.initials: FD
authors.lastname: Jousan
authors.forename: Lilian J
authors.initials: LJ
authors.lastname: Oliveira
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hansen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D046149:Embryo Culture Techniques; D047108:Embryonic Development / Q000187:drug effects* / Q000502:physiology; D005307:Fertilization in Vitro; D018869:Heat-Shock Response / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013997:Time Factors
chemical_list: D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt