Transforming Growth Factor-? (TGF-?) Directly Activates the JAK1-STAT3 Axis to Induce Hepatic Fibrosis in Coordination with the SMAD Pathway.

ABSTRACT: Transforming growth factor-? (TGF-?) signals through both SMAD and non-SMAD pathways to elicit a wide array of biological effects. Existing data have shown the association and coordination between STATs and SMADs in mediating TGF-? functions in hepatic cells, but it is not clear how STATs are activated under these circumstances. Here, we report that JAK1 is a constitutive TGF?RI binding protein and is absolutely required for phosphorylation of STATs in a SMAD-independent manner within minutes of TGF-? stimulation. Following the activation of SMADs, TGF-? also induces a second phase of STAT phosphorylation that requires SMADs, de novo protein synthesis, and contribution from JAK1. Our global gene expression profiling indicates that the non-SMAD JAK1/STAT pathway is essential for the expression of a subset of TGF-? target genes in hepatic stellate cells, and the cooperation between the JAK1-STAT3 and SMAD pathways is critical to the roles of TGF-? in liver fibrosis.

SUBMITTER: Tang LY 

PROVIDER: S-EPMC5354477 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature