Transforming growth factors beta 1, beta 2, and beta 3 messenger RNA and protein expression in mouse uterus and vagina during estrogen-induced growth: a comparison to other estrogen-regulated genes.

Increasing evidence suggests that the differential regulation of multiple peptide growth factors by steroid hormones contributes significantly to the pleiotropic effects elicited in target tissues. We report here an evaluation of the effects of the potent estrogen, diethylstilbestrol, on the expression of the three mammalian transforming growth factor beta (TGF beta) isoforms, TGF beta 1, TGF beta 2, and TGF beta 3, in both the uterus and the vagina of the prepubescent mouse. Immunohistochemical protein detection, in situ hybridization, and Northern RNA analyses demonstrate overlapping but distinct time-dependent and site-specific induction of all three TGF beta genes in the reproductive tract in response to estrogen. Temporal analysis of steady-state levels of the TGF beta mRNAs in the uterus by Northern blotting clearly demonstrates that diethylstilbestrol significantly but transiently up-regulates TGF beta 3 mRNA within 30 min and TGF beta 1 and TGF beta 2 mRNAs by 3 h with decreases to/or below control levels by 6 h. The vagina also responds to diethylstilbestrol with similar kinetics of induction for TGF beta 2 and TGF beta 3 mRNAs as that observed in the uterus; however, TGF beta 1 mRNA levels increase gradually and peak around 16 h after treatment. Investigation of the steroid specificity demonstrates predominant estrogen specificity in the control of TGF beta expression in the immature mouse reproductive tract. In situ hybridization localizes the mRNAs for all three TGF beta isoforms, primarily to the uterine and vaginal epithelium. Unlike the transient nature of TGF beta mRNA induction elicited by estrogen, immunohistochemistry demonstrates that estrogen treatment results in a more prolonged elevation of the proteins for TGF beta 1, TGF beta 2, and TGF beta 3 in the epithelium of both tissues. Investigation of specific binding of 125I-TGF beta 1 by affinity labeling reveals the existence of the receptor/binding proteins (types I, II, and III) in the uterus. Estrogen treatment significantly reduces binding to each of these components in the uterus, which suggests that estrogen may modulate TGF beta responsiveness at the receptor level. A comparison of TGF beta mRNA expression to the induction of other estrogen-regulated genes, TGF alpha, insulin-like growth factor-1, c-myc, progesterone receptor and lactotransferrin reveals that, in general, the TGF beta transcript levels are regulated in a more transient manner by estrogen.(ABSTRACT TRUNCATED AT 400 WORDS)

Duke Scholars

Author David Keith Walmer Duke Global Health Institute