EMBRYONIC EXPRESSION PATTERN OF H218, A G-PROTEIN COUPLED RECEPTOR HOMOLOG, SUGGESTS ROLES IN EARLY MAMMALIAN NERVOUS-SYSTEM DEVELOPMENT

Heterologous expression studies employing mammalian cell tissue cultur e techniques and in vivo studies of lower eukaryotes suggest that G-pr otein coupled receptors may play critical roles in regulating early st ages of vertebrate nervous system development. Previous work suggests that H218, a rat G-protein coupled receptor homolog, could serve such a role. Most importantly, northern blot data indicate that whole brain H218 mRNA levels are highest during embryogenesis. In the present stu dies we raised, affinity-purified and characterized several anti-H218, polyclonal antisera and immunohistochemically mapped the expression o f H218 during the early stages of rat embryonic nervous system develop ment. The resulting data indicate that H218 is preferentially expresse d in young, differentiating neuronal cell bodies and axons. Moreover, the expression is temporally regulated such that highest H218 levels a re found in neuronal cell bodies during their early stages of differen tiation and in axons during their outgrowth. Therefore, we propose tha t H218 signal transduction may widely participate in the regulation of some of the first steps in neuronal differentiation including axon ou tgrowth. (C) 1997 IBRO.