Our data provide a model in which miR-23b miRNAs repress bile duct gene expression in fetal hepatocytes while promoting their growth by down-regulating Smads and consequently TGFbeta signaling. Concomitantly, low levels of the miR-23b miRNAs are needed in cholangiocytes to allow TGFbeta signaling and bile duct formation.

Bile duct morphogenesis involves sequential induction of biliary specific gene expression, bilayer generation, cell proliferation, remodeling and apoptosis. HBC-3 cells are a model system to study differentiation of hepatoblasts along the hepatocytic or bile ductular lineage in vitro and in vivo. We used microarray to define molecular pathways during ductular differentiation in response to Matrigel. The temporal pattern of expression of marker genes induced was similar to that observed during bile duct formation in vivo. Notch, HNF1beta, Polycystic kidney disease 2, Bicaudal C 1 and beta-catenin were up regulated during the time course. Functional clustering analysis revealed significant up regulation of clusters of genes involved in extracellular matrix remodeling, ion transport, vacuoles, lytic vacuoles, pro-apoptotic and anti-apoptotic genes, transcription factors and negative regulators of the cell proliferation, while genes involved in the cell cycle were significantly down regulated. Notch signaling pathway was activated by treatment with Matrigel. In addition, TGFbeta/BMP signaling pathway members including the type I TGFbeta receptor and Smads 3, 4 and 5 were significantly up regulated, as were several TGFbeta/BMP responsive genes including Hey 1, a regulator of Notch pathway signaling. SMADS 3, 4 and 5 were present in the nuclear fraction of HBC-3 cells during ductular differentiation in vitro, but not during hepatocyte differentiation. SMAD 5 was preferentially expressed in hepatoblasts undergoing bile duct morphogenesis in the fetal liver, while the TGFbeta/BMP signaling antagonist chordin, was expressed throughout the liver suggesting a mechanism by which TGFbeta/BMP signaling is limited to hepatoblasts that contact portal mesenchyme in vivo.

Patients and clinicians alike view anonymous testing as a potential way to avoid perceived risks of genetic testing such as insurance and employment discrimination and the potential loss of privacy. To assess their experience with and attitudes towards anonymous testing for BRCA1/2, genetic counselors were invited to complete an internet-based survey via the NSGC Familial Cancer Risk Counseling Special Interest Group (FCRC-SIG) listerv. A majority of the 115 respondents (70%) had received requests from patients for anonymous BRCA1/2 testing at some point in their careers and 43% complied with this request. Most counselors, however, encountered such requests infrequently, 1-5 times per year. Although genetic counselors do not generally encourage anonymous testing and over a third of respondents feel it should never be offered, a substantial subset support its use under specific circumstances. In general, a strong consensus exists among counselors that anonymous testing should not be offered routinely. In light of the current legislative landscape, it is of note that a substantial proportion of respondents (42.7%) cited the threat of life insurance discrimination as a reason for pursuing AT, and fewer cited health insurance (30.0%) or employment discrimination (29.1%) as justifications. Since there exists no federal legislative protections against discrimination by life insurance companies, it makes sense that genetic counselors were more responsive to this issue as opposed to the threat of discrimination in health insurance and employment.

No abstract