Activin and follistatin in rat mammary gland.
Mammary gland morphogenesis and differentiation are mediated through the combined activities of systemic hormones and locally synthesized growth factors. Activin, a member of the transforming growth factor (TGF)-beta superfamily, is known to regulate the growth and differentiation of several cell types. In the present study, we investigated the role of activin in rat mammary gland on different stages of development. We found that activin A in vitro inhibits the proliferation of isolated acini, and this effect increases with the development of the gland. This factor also produces in vitro an inhibition of the final differentiation of acini obtained from 19th day pregnant rats. We also report the expression of activin receptors IIA and IIB mRNA in whole rat mammary gland and acini, with decreased levels of expression of type IIA (in both compartments) and IIB (in acini) during pregnancy and lactogenesis. In addition, we show that activin betaB-subunit mRNA decreases throughout pregnancy, and that the mRNA levels of follistatin (Fst) (its ligand protein) are high in cycling rats and at the beginning of pregnancy and diminish thereafter, having the acini higher levels of expression. Our data show that activin betaB-subunit, follistatin and ActRIIA and IIB transcripts are expressed in rat mammary gland at appropriate times and locations during development, allowing an interplay that might regulate activin action on growth and differentiation of the gland.
Bussmann
Ursula A
UA
Instituto de Biología y Medicina Experimental, Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina.
Lanuza
Guillermo M
GM
Bussmann
Leonardo E
LE
D029404:Activin Receptors / Q000096:biosynthesis / Q000235:genetics; D028341:Activins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D002364:Caseins / Q000096:biosynthesis / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D038681:Follistatin / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D005786:Gene Expression Regulation; D028322:Inhibin-beta Subunits / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D007265:Inhibins / Q000096:biosynthesis / Q000235:genetics; D007774:Lactation / Q000502:physiology; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D002364:Caseins; D038681:Follistatin; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C422405:activin A; C103008:inhibin beta A subunit; C094377:inhibin-alpha subunit; D028341:Activins; D007265:Inhibins; D028322:Inhibin-beta Subunits; D029404:Activin Receptors