Feng Zhang

BACKGROUND AND AIMS: Aerobic glycolysis reprogramming occurs during HSC activation, but how it is initiated and sustained remains unknown. We investigated the mechanisms by which canonical Wnt signaling regulated HSC glycolysis and the therapeutic implication for liver fibrosis. APPROACH AND RESULTS: Glycolysis was examined in HSC-LX2 cells upon manipulation of Wnt/β-catenin signaling. Nuclear translocation of lactate dehydrogenase A (LDH-A) and its interaction with hypoxia-inducible factor-1α (HIF-1α) were investigated using molecular simulation and site-directed mutation assays. The pharmacological relevance of molecular discoveries was intensified in primary cultures, rodent models, and human samples. HSC glycolysis was enhanced by Wnt3a but reduced by β-catenin inhibitor or small interfering RNA (siRNA). Wnt3a-induced rapid transactivation and high expression of LDH-A dependent on TCF4. Wnt/β-catenin signaling also stimulated LDH-A nuclear translocation through importin β2 interplay with a noncanonical nuclear location signal of LDH-A. Mechanically, LDH-A bound to HIF-1α and enhanced its stability by obstructing hydroxylation-mediated proteasome degradation, leading to increased transactivation of glycolytic genes. The Gly28 residue of LDH-A was identified to be responsible for the formation of the LDH-A/HIF-1α transcription complex and stabilization of HIF-1α. Furthermore, LDH-A-mediated glycolysis was required for HSC activation in the presence of Wnt3a. Results in vivo showed that HSC activation and liver fibrosis were alleviated by HSC-specific knockdown of LDH-A in mice. β-catenin inhibitor XAV-939 mitigated HSC activation and liver fibrosis, which were abrogated by HSC-specific LDH-A overexpression in mice with fibrosis. CONCLUSIONS: Inhibition of HSC glycolysis by targeting Wnt/β-catenin signaling and LDH-A had therapeutic promise for liver fibrosis.

Introduction: The therapies of using exosomes derived from mesenchymal stem cells (MSC-Exo) for wound healing and scar attenuation and micro RNAs (miRNAs) for regulation of genes by translational inhibition and mRNA destabilization obtained great achievements. Silent information regulator 1 (SIRT1) is the silent information, which has an intricate role in many biological processes. However, the effects of SIRT1 and miR-138-5p loaded in MSC-Exo on pathological scars remain unclear. Methods: MSC-Exo was isolated and identified by ultracentrifugation, transmission electron microscopy, nanoparticle size measuring instrument and Western blot assays. The relationship between SIRT1 and miR-138-5p was verified by a double-luciferase reporter assay. Cell Counting Kit-8, Τranswell, scratch, and Western blot assays were used to evaluate the proliferation and migration of human skin fibroblasts (HSFs), and the protein expression of SIRT1, NF-κB, α-SMA and TGF-β1 in HSFs, respectively. Flow cytometry was used to assess the apoptosis and cell cycle of HSFs affected by SIRT1. Results: Our study demonstrated that miR-138-5p loaded in MSC-Exo could attenuate proliferation, migration and protein expression of HSFs-derived NF-κB, α-SMA, and TGF-β1 by targeting to SIRT1 gene, which confirmed the potential effects of MSC-Exo in alleviating pathological scars by performing as a miRNA's delivery vehicle. Conclusion: Exosomes derived from MSCs acting as a delivery vehicle to deliver miR-138-5p can downregulate SIRT1 to inhibit the growth and protein expression of HSFs and attenuate pathological scars.

Liver fibrosis is a repair process of chronic liver injuries induced by toxic substances, pathogens, and inflammation, which exhibits a feature such as deposition of the extracellular matrix. The initiation and progression of liver fibrosis heavily relies on excessive activation of hepatic stellate cells (HSCs). The activated HSCs express different kinds of chemokine receptors to further promote matrix remodulation. The long-term progression of liver fibrosis will contribute to dysfunction of the liver and ultimately cause hepatocellular carcinoma. The liver also has abundant innate immune cells, including DCs, NK cells, NKT cells, neutrophils, and Kupffer cells, which conduct complicated functions to activation and expansion of HSCs and liver fibrosis. Autophagy is one specific type of cell death, by which the aberrantly expressed protein and damaged organelles are transferred to lysosomes for further degradation, playing a crucial role in cellular homeostasis. Autophagy is also important to innate immune cells in various aspects. The previous studies have shown that dysfunction of autophagy in hepatic immune cells can result in the initiation and progression of inflammation in the liver, directly or indirectly causing activation of HSCs, which ultimately accelerate liver fibrosis. Given the crosstalk between innate immune cells, autophagy, and fibrosis progression is complicated, and the therapeutic options for liver fibrosis are quite limited, the exploration is essential. Herein, we review the previous studies about the influence of autophagy and innate immunity on liver fibrosis and the molecular mechanism to provide novel insight into the prevention and treatment of liver fibrosis.

Background: Liver cancer treatment encounters considerable therapeutic challenges, especially because hypoxic microenvironments markedly reduce sensitivity to chemotherapeutic agents. TFAM (mitochondrial transcription factor A) plays a crucial role in maintaining mitochondrial function. Oroxylin A (OA), a flavonoid with potential therapeutic properties, demonstrated prospects in cancer treatment. However, the mechanism of the sensitizing effect of OA on cancer cells has not been elucidated. Methods: MTT assays were utilized to evaluate a hypoxia-induced resistance model. Plate colony formation assays, TEM, and JC-1 staining were used to examine the effects of siTFAM on proliferation and mitochondrial damage of HepG2 cells. Cox8-EGFP-mCherry plasmid transfection, LysoTracker and MitoTracker colocalization analysis, and WB were conducted to evaluate the influence of OA on mitophagy. The effect of OA on p53 ubiquitination levels was investigated by Co-IP and the CHX chase assay. A mouse xenograft tumor model was utilized to assess the therapeutic effect of OA on HepG2 cells in vivo. Results: OA significantly improved the inhibitory effect of sorafenib by inhibiting mitophagy on HepG2 cells in in vitro and in vivo models. Notably, the molecular docking and thermal shift assays indicated a clear binding of OA and TFAM. Further research revealed that OA suppressed p53 acetylation and promoted its degradation by downregulating TFAM expression, which ultimately inhibited mitophagy in hypoxia. Conclusions: OA has demonstrated the potential to enhance the efficacy of sorafenib treatment for liver cancer, and TFAM may be one of its targets.