A NEW FAMILY OF GROWTH AND DIFFERENTIATION FACTORS DERIVED FROM THE N-TERMINAL DOMAIN OF PROOPIOMELANOCORTIN (N-POMC)

There is a large body of in vitro evidence that pituitary function is not only dependent on hormonal signals from the brain but also on para crine signals produced in the tissue itself. These signals appear to b e involved in the control of pituitary hormone secretion as well as in pituitary cell differentiation and development (for review see Denef C. Paracrine mechanisms in the pituitary. In: Imura H, editor. The pit uitary gland, 2nd ed. Raven Press, 1994: 351-378; Denef C. Autocrine/p aracrine intermediates in hormone action and modulation of cellular re sponses to hormones. In: Conn M, editor. Handbook of Physiology. New Y ork: Oxford University Press, 1998 (in press)). The paracrine factors which have been identified in the pituitary belong to diverse biologic al molecules such as neuropeptides, acetylcholine, growth factors, cyt okines and posttranslationally modified derivatives of pituitary hormo ne such as cleaved prolactin (PRL) and the gonadotropin a-subunit. Rec ently, we have identified several N-terminal fragments of the polypept ide proopiomelanocortin (POMC) as a novel family of growth and differe ntiation factors in the rat anterior pituitary. (C) 1998 Elsevier Scie nce Inc. All rights reserved.