Involvement of autocrine mechanism of transforming growth factor-β in the functional differentiation of pregnant mouse mammary gland

Abstract

Yamamoto T, Komura H, Morishige K, Tadokoro C, Sakata M, Kurachi H, Miyake A. Involvement of autocrine mechanism of transforming growth factor-β in the functional differentiation of pregnant mouse mammary gland. Eur J Endocrinol 1994;130:302–7. ISSN 0804–4643 We studied the presence and possible role of the autocrine mechanism of transforming growth factor-β (TGF-β) in pregnant mouse mammary gland. Northern blot analysis revealed the expression of the TGF-β1 gene transcript at 2.5 kb in mammary epithelial cells isolated from virgin and mid-pregnant mice. The TGF-β activity was higher in the conditioned medium from mid-pregnant mouse mammary explants than that from virgin explants by a bioassay system using mink lung epithelial cells. A binding study using [125I]TGF-β1 as a ligand showed that pregnant mouse mammary epithelial cells possessed a single class of high-affinity TGF-β1 binding sites (Kd = 28.0 pmol/l, 1.2 × 104 sites per cell). These results suggested the presence of a TGF-β autocrine mechanism in pregnant mouse mammary epithelial cells. Next, we examined the effect of TGF-β1 on the functional differentiation of pregnant mouse mammary gland. Transforming growth factor-β1 inhibited α-lactalbumin production in cultured mammary explants from mid-pregnant mice in a dose-dependent manner without inhibiting DNA synthesis. All these results suggest that TGF-β may play a role in regulating the functional differentiation of mouse mammary glands during pregnancy. Hirohisa Kurachi, Department of Obstetrics and Gynecology, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565, Japan