SEROTONIN AND ACETYLCHOLINE MODULATE THE SENSITIVITY OF EARLY SEA-URCHIN EMBRYOS TO PROTEIN-KINASE-C ACTIVATORS

The protein kinase C activators 1-oleoyl-2-acetyl-rac-glycerol (OAG) a nd phorbol 12-myristate 13-acetate (PMA) evoke similar developmental a nomalies in early embryos of sea urchins, that is, block of cleavage d ivisions, formation of giant polyploid nuclei with nucleolus-like incl usions, damage of cortical microfilaments and extrusion of small cytop lasts (mini-cells). Protein kinase inhibitors belonging to two differe nt chemical groups (derivatives of isoquinoline and naphthalene) prote ct the embryos against OAG and PMA action. Some of these inhibitors (H -7, H-8, and H-9) also weaken the effects of 5-HT antagonists. 5-HT we akens and acetylcholine (ACh) potentiates the developmental anomalies evoked by PMA and GAG. It is suggested that endogenous 5-HT and ACh of early sea urchin embryos are functionally coupled with second messeng er systems acting through the regulation of protein kinase C activity. (C) 1998 Elsevier Science Inc. All rights reserved.