title: Analysis of mRNA associated factors during bovine oocyte maturation and early embryonic development.
abstract: Regulation of gene expression at the translational level is particularly essential during developmental periods, when transcription is impaired. According to the closed-loop model of translational initiation, we have analyzed components of the 5 -mRNA cap-binding complex eIF4F (eIF4E, eIF4G, eIF4A), the eIF4E repressor 4E-BP1, and 3 -mRNA poly-(A) tail-associated proteins (PABP1 and 3, PAIP1 and 2, CPEB1, Maskin) during in vitro maturation of bovine oocytes and early embryonic development up to the 16-cell stage. Furthermore, we have elucidated the activity of distinct kinases which are potentially involved in their phosphorylation. Major phosphorylation of specific target sequences of PKA, PKB, PKC, CDKs, ATM/ATR, and MAPK were observed in M II stage oocytes. Furthermore, main changes in the abundance and/or phosphorylation of distinct mRNA-binding factors occur at the transition from M II stage oocytes to 2-cell embryos. In conclusion, the results indicate that, at the transition from oocyte to embryonic development, translational initiation is regulated by striking differences in the abundance and/or phosphorylation of 5 -end and 3 -end mRNA associated factors, mainly the poly-(A) bindings proteins PABP1 and 3, their repressor PAIP2 and a Maskin-like protein with distinct eIF4E-binding properties which prevents eIF4E/cap binding and eIF4F formation in vitro. Nevertheless, from the M II stage to 16-cell embryos a substantial amount of eIF4E and, to a lesser extent, of eIF4G was precipitated by (7)m-GTP-Separose indicating eIF4F complex formation. Therefore, it is likely that in general the reduction in PABP1 and 3 abundance represses overall translation during early embryonic development.
authors.affiliation: Research Institute for the Biology of Farm Animals (FBN) Dummerstorf, 18196 Dummerstorf, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Siemer
authors.forename: Tatjana
authors.initials: T
authors.lastname: Smiljakovic
authors.forename: Monika
authors.initials: M
authors.lastname: Bhojwani
authors.forename: Claus
authors.initials: C
authors.lastname: Leiding
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Kanitz
authors.forename: Michal
authors.initials: M
authors.lastname: Kubelka
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Tomek
mesh_terms: D000818:Animals; D002417:Cattle; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro; D018507:Gene Expression Regulation, Developmental; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D011247:Pregnancy; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D012315:RNA Caps / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D012315:RNA Caps; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011494:Protein Kinases