Y Sadovsky — Page 4 | PubMed Health

PubMedDate not supplied

The kinase p38 regulates peroxisome proliferator activated receptor-gamma in human trophoblasts.

Deficiency of either the mitogen-activated protein kinase p38 or the nuclear receptor PPARgamma results in disrupted vasculogenesis and abnormal development of the murine placenta. In addition, PPARgamma regulates differentiation of human trophoblasts. Here we tested the hypothesis that p38 plays an important role in the regulation of PPARgamma in primary human trophoblasts. We initially confirmed that cultured trophoblasts derived from normal term human placentas express p38 as well as its functional phosphorylated form. Whereas PPARgamma did not alter p38 expression, p38 inhibitors diminished the transcriptional activity of PPARgamma in primary trophoblasts. In addition, inhibition of p38 resulted in marked attenuation of PPARgamma-stimulated hCG production by cultured trophoblast. Our data support an effect of p38 on PPARgamma protein stability because p38 inhibition led to reduced expression of PPARgamma protein without a significant effect on PPARgamma mRNA, and this reduction was blocked by the protease inhibitor MG-132. Together, these data indicate that p38 regulates PPARgamma expression and activity in term human trophoblasts. Cross talk between p38 and PPARgamma signaling may play a role in modulating differentiation and function of the human placenta.

Cells, Cultured↗

PubMedDate not supplied

Developmental and physiologic roles of the nuclear receptor steroidogenic factor-1 in the reproductive system.

OBJECTIVE: To characterize the unique features of steroidogenic factor-1 (SF-1) among members of the steroid receptor superfamily of proteins and review its role in reproductive development and function. METHODS: We reviewed all pertinent articles that describe structural or functional aspects of SF-1. We also introduced results obtained recently by our group. RESULTS: Unlike other steroid receptors, SF-1 binds as a monomer to a DNA response element, which is composed of an estrogen receptor "half site." Furthermore, SF-1 lacks a specific ligand that is required for either interaction with DNA or modulation of its transactivation function. Steroidogenic factor-1 is highly expressed in steroid-producing tissues and in gonadotrophs and plays a pivotal role in regulating the expression of enzymes and hormones essential for steroid biosynthesis pathways. A dramatic phenotype was revealed using SF-1 deficient mice: these mice lack gonads and adrenal glands, establishing SF-1 as an essential embryonic regulator of steroidogenic organ development. While SF-1 is required for basal expression of steroidogenic enzymes, its role in hormone-dependent regulation of reproductive function in vivo is uncertain, but its function may be subject to modulation by coactivators or corepressors and hormones, as well as by post-translational modifications. CONCLUSION: Steroidogenic factor-1 plays a key role in the development and differentiation of the reproductive system. Understanding the mechanism of action of SF-1 is expected to provide new clues to the etiology of maldevelopment of the gonads and adrenal glands, and to dysfunction associated with steroid biosynthesis during early embryonic development and throughout differentiation.

Adrenal Glands↗