Alleviation of hepatic fibrosis and autophagy via inhibition of transforming growth factor-ß1/Smads pathway through shikonin.

BACKGROUND AND AIM: Liver fibrosis is a worldwide clinical challenge during the progression of chronic liver disease to liver cirrhosis. Shikonin is extracted from the root of Lithospermum erythrorhizon with antioxidant, anti-inflammatory, anticancer, and wound-healing properties. The study aims to investigate the protective effect of shikonin on liver fibrosis and its underlying mechanism. METHODS: Two liver fibrosis models were established in male C57 mice by intraperitoneal injection of CCl4 or bile duct ligation. Shikonin was administered orally three times weekly at a dose of 2.5 or 5 mg/kg. Protein and mRNA expressions were assayed by quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemical staining. RESULTS: Shikonin significantly inhibited activation of hepatic stellate cells and extracellular matrix formation by downregulating the transforming growth factor-ß1 expression and maintaining the normal balance between metalloproteinase-2 and tissue inhibitor of metalloproteinase-1. Shikonin also decreased hepatic stellate cell energy production by inhibiting autophagy. CONCLUSIONS: The results confirmed that shikonin attenuated liver fibrosis by downregulating the transforming growth factor-ß1/Smads pathway and inhibiting autophagy.

Salvanic acid B inhibits myocardial fibrosis through regulating TGF-ß1/Smad signaling pathway.

OBJECTIVE: Salvanic Acid B (Sal B) was proved to show significant effect against fibrosis and myocardial injury. This study aimed to investigate the protective effects and the mechanisms of Sal B on myocardial fibrosis. METHODS: The mice were randomly assigned to five groups: control group, model group, positive group, low-dose group, high-dose group. Hematoxylin-Eosin (HE) staining and Masson staining were used to assess the myocardial physiological changes and measure the myocardial fibrosis area. Expression of transforming growth factor-beta (TGF-ß), drosophila mothers against decapentaplegic (Smad)2, Smad3 and Smad7 were analyzed by immunohistochemistry and real-time PCR. On the other hand, mouse cardiac fibroblasts (CFs) cells were co-treated with 20 ng/mL TGF-ß1 and different concentrations of Sal B (5, 10, and 20 ng/mL) for 24 h. The cells morphology changes were assessed under a microscope, and the protein expressions induced by TGF-ß1 were detected by Western blot. RESULTS: Compared with the model group, myocardial collagen fibers decreased obviously with Sal B treatment (p < 0.05). Moreover, the expression of key signal molecules of the TGF-ß/Smads signaling pathway, including TGF-ß1, Smad2 and Smad3 proteins decreased, while the expression of Smad7 increased in Sal B treatment groups as compared to those of the model group (p < 0.05). On the other hand, results of CFs studies were also consistent with those animals. CONCLUSIONS: Sal B could inhibit the myocardial fibrosis process through regulating TGF-ß/Smads signal transduction pathways.

BMP receptor-activated Smads confer diverse functions during the development of the dorsal spinal cord.

Bone Morphogenetic Proteins (BMPs) have multiple activities in the developing spinal cord: they specify the identity of the dorsal-most neuronal populations and then direct the trajectories of dorsal interneuron (dI) 1 commissural axons. How are these activities decoded by dorsal neurons to result in different cellular outcomes? Our previous studies have shown that the diverse functions of the BMPs are mediated by the canonical family of BMP receptors and then regulated by specific inhibitory (I) Smads, which block the activity of a complex of Smad second messengers. However, the extent to which this complex translates the different activities of the BMPs in the spinal cord has remained unresolved. Here, we demonstrate that the receptor-activated (R) Smads, Smad1 and Smad5 play distinct roles mediating the abilities of the BMPs to direct cell fate specification and axon outgrowth. Smad1 and Smad5 occupy spatially distinct compartments within the spinal cord, with Smad5 primarily associated with neural progenitors and Smad1 with differentiated neurons. Consistent with this expression profile, loss of function experiments in mouse embryos reveal that Smad5 is required for the acquisition of dorsal spinal neuron identities whereas Smad1 is critical for the regulation of dI1 axon outgrowth. Thus the R-Smads, like the I-Smads, have discrete roles mediating BMP-dependent cellular processes during spinal interneuron development.

Hypoxic conversion of SMAD7 function from an inhibitor into a promoter of cell invasion.

Smad7 is an inhibitor of the transforming growth factor-beta-activated signaling pathway. Under well-oxygenated conditions, Smad7 is a potent inhibitor of carcinoma cell invasion. Paradoxically, however, the expression of Smad7 is upregulated across several cancers and may promote cancer progression. Hypoxia, which is frequently met in solid tumors, is an enhancer of carcinoma cell invasion and cancer progression. Here, we report that hypoxia activates the expression of Smad7 in a hypoxia-inducible factor- and von Hippel-Lindau protein-dependent manner. As expected, in normoxia, the forced expression of Smad7 inhibited carcinoma cell invasion. In contrast with the normoxic condition, the inhibitory effect of Smad7 was lost under hypoxia. The block in carcinoma cell invasion by forced expression of Smad7 was released by hypoxia in two invasive carcinoma cell lines. Moreover, the noninvasive HaCaT keratinocytes become invasive upon simultaneous hypoxia and transforming growth factor-beta stimulus. The hypoxia-activated invasion was attenuated by inhibiting Smad7 expression by short interfering RNA. Finally, the increased Smad7 expression in human carcinomas correlated with hypoxic gene expression. The data provide evidence that hypoxia could convert Smad7 function from an invasion inhibitor into an activator of invasion. Furthermore, they might shed light as to why increased Smad7 expression is detected in cancers.