Mouse anti-Human INHBE monoclonal antibody, clone 5C6

Liver damage induces hepatic stellate cells (HSC) activation, characterised by a fibrogenic, proliferatiVe and migratory phenotype. Activated HSC are mainly regulated by transforming growth factor beta 1 (TGF beta 1), which increases the production of extracellular matrix proteins (e.g. collagen-I) promoting the progression of hepatic fibrosis. AGAP2 (ArfGAP with GTPase domain, ankyrin repeat and PH domain 2) is a GTPase/GTP-activating protein involved in the actin remodelling system and receptor recycling. In the present work the role of AGAP2 in human HSC in response to TGF beta 1 was investigated. LX-2 HSC were transfected with AGAP2 siRNA and treated with TGF beta 1. AGAP2 knockdown prevented to some extent the proliferative and migratory TGF beta 1-induced capacities of LX-2 cells. An array focused on human fibrosis revealed that AGAP2 knockdown partially prevented TGF beta 1-mediated gene expression of the fibrogenic genes ACTA2, COL1A2, EDN1, INHBE, LOX, PDGFB, TGEB12, while favored the expression of CXCR4, IL1A, MMP1, MMP3 and MMP9 genes. Furthermore, TGF beta 1 induced AGAP2 promoter activation and its protein expression in LX-2. Moreover, AGAP2 protein levels were significantly increased in liver samples from rats with thioacetamide-induced fibrosis. In addition, AGAP2 silencing affected TGF beta 1-receptor 2 (TGFR2) trafficking in U2OS cells, blocking its effective recycling to the membrane. AGAP2 silencing in LX-2 cells prevented the TGF beta 1-induced increase of collagen-I protein levels, while its overexpression enhanced collagen-I protein expression in the presence or absence of the cytokine. AGAP2 overexpression also increased focal adhesion kinase (FAK) phosphorylated levels in LX-2 cells. FAK and MEK1 inhibitors prevented the increase of collagen-I expression caused by TGF beta 1 in LX-2 overexpressing AGAP2. In summary, the present work shows for the first time, that AGAP2 is a potential new target involved in TGF beta 1 signalling, contributing to the progression of hepatic fibrosis.

Activin E, a secreted peptide encoded by the inhibin/activin beta E subunit gene, is a member of the transforming growth factor-beta superfamily, which is predominantly expressed in the liver. Recent reports have suggested that activin E plays a role in energy homeostasis as a hepatokine. Here, using transgenic mice overexpressing activin E under the control of the beta-actin promoter, we demonstrate that activin E controls energy metabolism through brown/beige adipocytes. The glucose tolerance test and insulin tolerance test showed that the insulin sensitivity was improved in the transgenic mice. Furthermore, the mice had a high body temperature compared with wild-type mice. The transgenic brown adipose tissue and mesenteric white adipose tissue showed upregulation of uncoupling protein 1, which enables energy dissipation as heat by uncoupling oxidative phosphorylation from ATP production. Present results indicate that activin E activates energy expenditure through brown/beige adipocyte activation, suggesting that activin E has high potential for obesity therapy.