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G protein gene expression during mouse oocyte growth and maturation, and preimplantation embryo development
Author(s) -
Williams Carmen J.,
Schultz Richard M.,
Kopf Gregory S.
Publication year - 1996
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/(sici)1098-2795(199607)44:3<315::aid-mrd5>3.0.co;2-p
Subject(s) - biology , heterotrimeric g protein , oocyte activation , embryo , oocyte , microbiology and biotechnology , g protein , signal transduction , genetics
Fertilization in mammals initiates “egg activation,” a series of events leading to embryo development. The signal transduction events that occur as a result of sperm‐egg interactions and that initiate egg activation may be analogous to a ligand‐receptor‐effector pathway, but the details of this signaling pathway are poorly understood. Several lines of evidence support a role for guanine nucleotide‐binding regulatory proteins (G proteins) in mammalian egg activation. Prior to initiating studies to examine further the role of specific G proteins in sperm‐induced mouse egg activation, we needed to define the complement of G proteins expressed in the egg. Using a reverse transcription‐polymerase chain reaction (RT‐PCR) assay, the relative levels of mRNAs encoding specific G protein α, β, and γ subunits were determined in meiotically incompetent oocytes, fully‐grown competent oocytes, metaphase II‐arrested eggs, one‐, two‐, and eight‐cell embryos, and blastocysts. mRNA transcripts representing all of the heterotrimeric G protein families were present at all of the stages examined, and all underwent significant changes in their patterns of expression. The following heterotrimeric G protein mRNA transcripts were present in oocytes, eggs, or preimplantation embryos: Gαq family (q, 11, and 14), Gα12 family (12 and 13), Gαi family (i1, i2, i3, t2, z, and s), β subunits 1, 2, 4, and 5, and γ subunits 2, 3, 5, and 7. A recently described large molecular weight G protein, Gαh (Nakaoka et al., 1994: Science 264:1593–1596), was also present. Gα15, Gαt1, Gαolf, GαoA, Gβ3, Gγ1, and Gγ8 mRNA transcripts were not detected using this method. The most common pattern of expression observed was a maturation‐associated decrease followed by an increase after the two‐cell stage. Some transcripts, however, were expressed at low levels until the eight‐cell to blastocyst stages, whereas others were expressed at high levels in the oocyte but following maturation declined and remained at a low level throughout preimplantation development. © 1996 Wiley‐Liss, Inc.