DEVELOPMENTAL EXPRESSION OF A CANDIDATE MULLERIAN-INHIBITING SUBSTANCE TYPE-II RECEPTOR

We have isolated a candidate Mullerian inhibiting substance (MIS) type II receptor complementary DNA from an embryonic rat urogenital ridge library and have studied its binding to MIS, its developmental pattern of expression and tissue distribution. By in situ hybridization with a full-length riboprobe, the receptor is expressed in the mesenchymal cells surrounding the Mullerian duct at embryonic days 14, 15, and 16 and in tubular and follicular structures of the rat fetal gonads. Expr ession of the messenger RNA was also seen in the granulosa cells and s eminiferous tubules of pubertal gonads. Northern analysis revealed tha t the MIS type II receptor messenger RNA is highly expressed in embryo nic, pubertal, and adult testes and ovaries, as well as in the gravid uterus. The timing of expression in the gonads of both sexes was also analyzed by Northern analyses that showed high levels of expression at the time of Mullerian duct regression, much lower levels neonatally a nd prepubertally and then increased expression again with sexual matur ation. The tissue and developmental specificity of expression of this receptor, which make it likely that this is the functional MIS type II receptor, can be used to advantage in therapeutic targeting strategie s and to decipher the function of MIS in the gonads.