Activation of FoxO3a/Bim axis in patients with Primary Biliary Cirrhosis.

BACKGROUND/AIMS: Impaired regulation of apoptosis has been suggested to play a role in the pathogenesis of Primary Biliary Cirrhosis (PBC). In this study, we analysed a signalling pathway that comprises the transcription factor FoxO3a and its downstream target Bim, a Bcl-2 interacting mediator of apoptosis. MATERIALS & METHODS: The tissues examined included livers explanted from patients with cirrhotic PBC, primary sclerosing cholangitis (PSC), alcoholic liver disease (ALD) and liver biopsies from patients with non-cirrhotic PBC. Large margin resections of hepatocellular carcinoma were used as controls. RESULTS: Expression of FoxO3a and Bim mRNA was significantly enhanced in both non-cirrhotic and end-stage PBC (2.2-fold and 4.3-fold increases, respectively), but not in the other disorders. Similarly, FOXO3a protein level was increased in end-stage PBC (P < 0.05 vs. control). A significant increase in Bim mRNA in non-cirrhotic and cirrhotic PBC was observed (2.2-fold and 8.2-fold respectively). In addition, the most pro-apoptotic isoform of Bim dominated in livers of PBC patients (2.5- fold increase vs. control; P < 0.05). Enhanced FoxO3a and Bim expression was associated with a substantial activation of caspase-3 in PBC (2-fold increase vs. controls; P < 0.0001), whereas it was decreased in both ALD and PSC (46% and 67% reductions respectively). The relationship between FoxO3a and Bim was further investigated in the livers of FoxO-deficient mice. The somatic deletion of FoxO3a caused a significant decrease in Bim, but not caspase-3 protein expression confirming the crucial role of FoxO3a in induction of Bim gene transcription. CONCLUSIONS: Our results imply that the FoxO3/Bim signalling pathway can be of importance in the livers of patients with PBC.

Angiogenesis within the duodenum of patients with cirrhosis is modulated by mechanosensitive Kruppel-like factor 2 and microRNA-126.

BACKGROUND: The mechanism involved in neovascularization in splanchnic circulation and the main trigger that induces angiogenesis in patients with cirrhosis are not fully recognized. AIMS: To explore the involvement of flow sensitive lung Kruppel-like factor (KLF2), microRNA-126 (miR-126), angiopoietin-2 (Ang-2) and heme oxygenase-1 (HO-1) in modulation of vascular endothelial growth factor (VEGF) signalling that have a critical effect on growth of new blood vessels. METHODS: Duodenal biopsies from 22 patients with cirrhosis and 10 controls were obtained during routine endoscopy. The process of angiogenesis was evaluated by a measurement of CD31 concentration, immunodetection of CD34 protein and estimation of capillary densities. Messenger RNA (mRNA) and protein expressions were analysed by real-time PCR, Western blot or ELISA respectively. RESULTS: Markers of angiogenesis (both, CD31 and CD34) were significantly enhanced in cirrhotic patients. In comparison to healthy controls, levels of Ang-2 and KLF-2 mRNAs as well as Ang-2, KLF-2, HO-1, VEGF protein expressions were considerably increased. Levels of sCD163, a surrogate marker of portal hypertension, correlated with levels of Ang-2, (P = 0.021) and VEGF (P = 0.009). The expression of miR-126, a KLF2-mediated regulator of the VEGF signalling was enhanced in cirrhotic patients. CONCLUSIONS: Our results demonstrate, for the first time in humans, that neovascularization is induced in duodenal tissue of patients with cirrhosis and proangiogenic factors such as KLF-2, Ang-2, miR-126 and VEGF can contribute to the angiogenesis induced by hemodynamic forces. Thus, cirrhosis-induced blood flow and pressure within splanchnic vessels may be important hemodynamic triggers that initiate the angiogenic signalling cascade.

Modulated DISP3/PTCHD2 expression influences neural stem cell fate decisions.

Neural stem cells (NSCs) are defined by their dual ability to self-renew through mitotic cell division or differentiate into the varied neural cell types of the CNS. DISP3/PTCHD2 is a sterol-sensing domain-containing protein, highly expressed in neural tissues, whose expression is regulated by thyroid hormone. In the present study, we used a mouse NSC line to investigate what effect DISP3 may have on the self-renewal and/or differentiation potential of the cells. We demonstrated that NSC differentiation triggered significant reduction in DISP3 expression in the resulting astrocytes, neurons and oligodendrocytes. Moreover, when DISP3 expression was disrupted, the NSC "stemness" was suppressed, leading to a larger population of cells undergoing spontaneous neuronal differentiation. Conversely, overexpression of DISP3 resulted in increased NSC proliferation. When NSCs were cultured under differentiation conditions, we observed that the lack of DISP3 augmented the number of NSCs differentiating into each of the neural cell lineages and that neuronal morphology was altered. In contrast, DISP3 overexpression resulted in impaired cell differentiation. Taken together, our findings imply that DISP3 may help dictate the NSC cell fate to either undergo self-renewal or switch to the terminal differentiation cell program.

Ursodeoxycholic acid influences the expression of p27kip1 but not FoxO1 in patients with non-cirrhotic primary biliary cirrhosis.

BACKGROUND: Enhanced expression of cell cycle inhibitor p27(kip1) suppresses cell proliferation. Ursodeoxycholic acid (UDCA) delays progression of primary biliary cirrhosis (PBC) but its effect on p27(kip1) expression is uncertain. AIMS: To analyze the expression of p27(kip1) and its transcription modulator FoxO1 in patients with PBC, and to assess the impact of UDCA on this pathway. MATERIALS AND METHODS: The examined human tissue included explanted livers from patients with cirrhotic PBC (n = 23), primary sclerosing cholangitis (PSC; n = 9), alcoholic liver disease (ALD; n = 9), and routine liver biopsies from patients with non-cirrhotic PBC (n = 26). Healthy liver samples served as controls (n = 19). Livers of FoxO-deficient mice were also studied. mRNA and protein expressions were analyzed by real-time PCR and Western blot. RESULTS: p27(kip1) expression was increased in cirrhotic and non-cirrhotic PBC. FoxO1 mRNA levels were increased in PBC (8.5-fold increase versus controls). FoxO1 protein expression in PBC was comparable to controls, but it was decreased in patients with PSC and ALD (63% and 70% reduction, respectively; both P < 0.05 versus control). UDCA-treated non-cirrhotic patients with PBC showed decreased expression of p27(kip1) mRNA. CONCLUSION: PBC progression is characterized by a FoxO1-independent increase of p27(kip1) expression. In early PBC, UDCA may enhance liver regeneration via p27(kip1)-dependent mechanism.

Neuropilin-1 functions as a VEGFR2 co-receptor to guide developmental angiogenesis independent of ligand binding.

During development, tissue repair, and tumor growth, most blood vessel networks are generated through angiogenesis. Vascular endothelial growth factor (VEGF) is a key regulator of this process and currently both VEGF and its receptors, VEGFR1, VEGFR2, and Neuropilin1 (NRP1), are targeted in therapeutic strategies for vascular disease and cancer. NRP1 is essential for vascular morphogenesis, but how NRP1 functions to guide vascular development has not been completely elucidated. In this study, we generated a mouse line harboring a point mutation in the endogenous Nrp1 locus that selectively abolishes VEGF-NRP1 binding (Nrp1(VEGF-)). Nrp1(VEGF-) mutants survive to adulthood with normal vasculature revealing that NRP1 functions independent of VEGF-NRP1 binding during developmental angiogenesis. Moreover, we found that Nrp1-deficient vessels have reduced VEGFR2 surface expression in vivo demonstrating that NRP1 regulates its co-receptor, VEGFR2. Given the resources invested in NRP1-targeted anti-angiogenesis therapies, our results will be integral for developing strategies to re-build vasculature in disease.