Moore G D, Kopf G S, Schultz R M
Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia 19104.
Dev Biol. 1993 Oct;159(2):669-78. doi: 10.1006/dbio.1993.1273.
Sperm-induced egg activation has several features in common with signal transduction pathways mediated by ligand-receptor-effector systems. G proteins are postulated to act as signal transducers regulating the plethora of cellular responses constituting egg activation that occur in response to sperm. We report that acetylcholine treatment of mouse eggs expressing the human m1 muscarinic receptor, a G protein-coupled receptor, results in the full complement of events of egg activation, including ZP2 to ZP2f conversion, recruitment of maternal mRNAs, pronuclear formation with subsequent DNA synthesis, cleavage to the two-cell stage, and activation of the embryonic genome. The induction of a full complement of sperm-induced egg activation events by ACh in the absence of sperm strongly suggests that sperm-induced egg activation is mediated by egg G proteins.
