Thymosin beta-4 regulates activation of hepatic stellate cells via hedgehog signaling

Abstract

The molecular mechanisms of thymosin beta-4 (TB4) involved in regulating hepatic stellate cell (HSC) functions remain unclear. Therefore, we hypothesize that TB4 influences HSC activation through hedgehog (Hh) pathway. HSC functions declined in a TB4 siRNA-treated LX-2. TB4 suppression downregulated both integrin linked kinase (ILK), an activator of smoothened, and phosphorylated glycogen synthase kinase 3 beta (pGSK-3B), an inactive form of GSK-3B degrading glioblastoma 2 (GLI2), followed by the decreased expression of both smoothened and GLI2. A TB4 CRISPR also blocked the activation of primary HSCs, with decreased expression of smoothened, GLI2 and ILK compared with cells transfected with nontargeting control CRISPR. Double immunostaining and an immunoprecipitation assay revealed that TB4 interacted with either smoothened at the cytoplasm or GLI2 at the nucleus in LX-2. Smoothened suppression in primary HSCs using a Hh antagonist or adenovirus transduction decreased TB4 expression with the reduced activation of HSCs. Tb4-overexpressing transgenic mice treated with CCl 4 were susceptible to the development hepatic fibrosis with higher levels of ILK, pGSK3b, and Hh activity, as compared with wild-type mice. These findings demonstrate that TB4 regulates HSC activation by influencing the activity of Smoothened and GLI2, suggesting TB4 as a novel therapeutic target in liver disease.

Thymosin β4 Prevents Oxidative Stress, Inflammation, and Fibrosis in Ethanol‐ and LPS‐Induced Liver Injury in Mice

“…Surprisingly, there is a decrease in PPAR γ expression in the T β 4-treated control. However, this result supports other reports which show that without liver injury, silencing T β 4 results in an increase in PPAR γ expression, and our results show that without liver injury, exogenously administering T β 4 results in a decrease in PPAR γ expression [ 59 , 62 ]. T β 4 also reduced the extent of fibrosis as measured by the percentage of collagen fibers and the amount of hydroxyproline in the liver tissue.…”

“…Hong et al demonstrated that T β 4 inhibited HSC activation by suppressing Notch signaling, thus attenuating liver fibrosis [ 61 ]. Others have shown that T β 4 regulates HSC activation via hedgehog signaling [ 62 ]. Additionally, depletion of T β 4 has shown to promote the proliferation, migration, and activation of HSC [ 63 ].…”

Thymosin β4 suppresses CCl4‐induced murine hepatic fibrosis by down‐regulating transforming growth factor β receptor‐II

“…Reyes-Gordillo et al 21 reported that administration of Tβ 4 prevented necrosis, inflammatory infiltration and up-regulation of α1 (and 2) collagen, α-smooth muscle actin (α-SMA), platelet-derived growth factor (PDGF)-β receptor, and fibronectin mRNA expression in a rat model of acute CCl 4 intoxication. A study by Kim et al 22 showed that exogenous Tβ 4 administration significantly attenuated CCl 4 -induced liver fibrosis in rats. This protective effect was attributed to the alleviation of oxidative stress and inflammation by Tβ4.…”

Thymosins in multiple sclerosis and its experimental models: moving from basic to clinical application

“…Tβ4 was initially employed as an anti-inflammatory agent (Badamchian et al, 2003;Girardi et al, 2003) and, subsequently, to inhibit proliferation and induce differentiation and apoptosis of leukemic cells (Huang et al, 2006). Recently, Tβ4 healing properties were described in skin, cornea and cardiac repair (Zhang et al, 2016a;Chopp and Zhang, 2015;Bock-Marquette et al, 2004;Badamchian et al, 2007;Li et al, 2017;Kim et al, 2017;Goldstein et al, 2012).…”

“…The epidermal growth factor receptor and the TLR signal transduction pathways may contribute to CNS remyelination and recovery of function induced by Tβ4 (Zhang et al, 2016a;Santra et al, 2014). Hedgehog signaling pathway was shown to be involved in activation of stem cells after Tβ4 treatment, which may contribute to therapeutic benefit (Kim et al, 2017).…”