Activation and transdifferentiation of liver-specific pericytes, i.e., the hepatic stellate cell (HSC), is the main step in the process of liver fibrogenesis.

To current knowledge, transforming growth factor L L (TGFL L) signaling is mandatory to establish liver fibrosis and various molecular interventions designed to affect the TGFL L system were successfully used to inhibit fibrogenesis. Activated hepatic stellate cells (HSC), which are one important source of TGFL L, are the major producers of extracellular matrix proteins in liver injury. We have previously shown that the TGFL L response of this cell type is modulated during the transdifferentiation process. This work delineates the activation of TGFL L downstream mediators, the Smads, in quiescent HSC and transdifferentiated myofibroblasts (MFB). The expression level of all Smads remained largely unchanged during this process. The response of HSC to TGFL L, leading to, e.g., induction of K K2 (I) collagen expression, is mediated by phosphorylation of Smad2 and Smad3 and subsequent nuclear translocation of a Smad containing complex. Neither TGFL L-dependent nor endogenously phosphorylated Smad2/3 was detectable in comparable amounts in transdifferentiated MFB, indicating loss of TGFL L sensitivity. Ectopic expression of Smad7 in HSC led to inhibition of Smad2 phosphorylation and abrogated TGFL L response. In transdifferentiated MFB, expression of a constitutively active TGFL L receptor I, but not treatment with TGFL L1, resulted in transcriptional activation of a TGFL L responsive promoter, thereby demonstrating completely restored TGFL L signal transduction. Our data indicate that in contrast to a postulated mechanism of enduring autocrine TGFL L signal transduction, early and late stages of HSC activation have to be distinguished, which is of importance for antifibrotic therapies. ß

In endometriosis lesions, the balance is tilted in favor of enzymes producing E(2). This is due to a suppression of types 2 and 4 17beta-HSD, and an increased expression of aromatase and type 1 17beta-HSD in ectopic endometrium.

The human progesterone receptor (PR) is a ligand-dependent transcription factor and two isoforms, (PRA and PRB), can be distinguished. PROGINS, a PR polymorphic variant, affects PRA and PRB and acts as a risk-modulating factor in several gynaecological disorders. Little is known about the functional consequences of this variant. Here, we characterise the properties of PROGINS with respect to transcription, mRNA maturation, protein activity and proliferation. PROGINS is characterised by a 320 bp PV/HS-1 Alu insertion in intron G and two point mutations, V660L in exon 4 and H770H (silent substitution) in exon 5. The Alu element contains a half oestrogen-response element/Sp1-binding site (Alu-ERE/Sp1), which acts as an in-cis intronic enhancer leading to increased transcription of the PROGINS allele in response to 17b-oestradiol. Moreover, Alu insertions in the human genome are frequently methylated. Our data indicate that the PROGINS-Alu does not affect gene transcription due to DNA methylation. However, the Alu element reduced the stability of the PROGINS transcript compared with the CP allele and does not generate splice variants. The amino acid substitution (V600L) in exon 4 leads to differences in PR phosphorylation and degradation in the two PR variants upon ligand binding, most likely as a result of differences in the three-dimensional structures of the two PR variants. As a consequence, the PR-L660 (PROGINS) variant (1) displays decreased transactivation activity in a luciferase reporter system and (2) is less efficient in opposing cell proliferation in hamster ovarian cells expressing human PRA, when compared with the PR-V660 (most common variant). Taken together, our results indicate that the PROGINS variant of PR is less responsive to progestin compared with the most common PR because of (i) reduced amounts of gene transcript and (ii) decreased protein activity.