Fibroblast growth factor 21 (FGF21) attenuates tacrolimus-induced hepatic lipid accumulation through transcription factor EB (TFEB)-regulated lipophagy / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Tacrolimus (TAC), also called FK506, is one of the classical immunosuppressants to prevent allograft rejection after liver transplantation. However, it has been proved to be associated with post-transplant hyperlipemia. The mechanism behind this is unknown, and it is urgent to explore preventive strategies for hyperlipemia after transplantation. Therefore, we established a hyperlipemia mouse model to investigate the mechanism, by injecting TAC intraperitoneally for eight weeks. After TAC treatment, the mice developed hyperlipemia (manifested as elevated triglyceride (TG) and low-density lipoprotein cholesterol (LDL-c), as well as decreased high-density lipoprotein cholesterol (HDL-c)). Accumulation of lipid droplets was observed in the liver. In addition to lipid accumulation, TAC induced inhibition of the autophagy-lysosome pathway (microtubule-associated protein 1 light chain 3β (LC3B) II/I and LC3B II/actin ratios, transcription factor EB (TFEB), protein 62 (P62), and lysosomal-associated membrane protein 1 (LAMP1)) and downregulation of fibroblast growth factor 21 (FGF21) in vivo. Overexpression of FGF21 may reverse TAC-induced TG accumulation. In this mouse model, the recombinant FGF21 protein ameliorated hepatic lipid accumulation and hyperlipemia through repair of the autophagy-lysosome pathway. We conclude that TAC downregulates FGF21 and thus exacerbates lipid accumulation by impairing the autophagy-lysosome pathway. Recombinant FGF21 protein treatment could therefore reverse TAC-caused lipid accumulation and hypertriglyceridemia by enhancing autophagy.

Berberine Inhibits Atherosclerosis by Regulating Lipophagy Via Targeting Wnt5a/NPC1 Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo investigate the regulatory effect and molecular mechanism of berberine （BBR） on lipophagy in the prevention and treatment of atherosclerotic （AS） lesions in mice. MethodFifty apolipoprotein E-knockout （ApoE-/-） mice were randomly divided into an AS model group， an atorvastatin group （5 mg·kg-1）， and low-， medium-， and high-dose BBR groups （2.5， 5， 10 mg·kg-1）. Ten C57BL/6J mice were assigned to the control group. After 12 weeks， hematoxylin-eosin （HE） and oil red O staining were performed to assess the histopathological changes of AS plaques in the aorta. Biochemical analysis was used to measure serum lipid levels， and enzyme-linked immunosorbent assay （ELISA） was employed to measure the levels of inflammatory cytokines interleukin-6 （IL-6） and tumor necrosis factor-α （TNF-α）， oxidative stress marker reactive oxygen species （ROS）， and serum lipophagy marker Beclin1 and microtubule-associated protein 1 light chain 3 Ⅱ （LC3Ⅱ）. The xanthine oxidase method was used to measure serum superoxide dismutase （SOD） activity. Immunohistochemistry （IHC） was used to detect the distribution of wingless-type MMTV integration site family member 5a （Wnt5a） and Nieman Pick type C1 （NPC1） in the aorta， and Western blot was used to determine the protein expression of Wnt5a and NPC1 in the aorta. ResultCompared with the control group， the AS model group showed significant AS plaque formation， significantly elevated levels of serum total cholesterol （TC）， triglycerides （TG）， low-density lipoprotein cholesterol （LDL-C）， IL-6， TNF-α， and ROS， aortic Wnt5a distribution and protein expression （P<0.01）， and significantly reduced levels of serum high-density lipoprotein cholesterol （HDL-C）， SOD， Beclin1， LC3Ⅱ， and aortic NPC1 distribution and protein expression （P<0.01）. Compared with the AS model group， the atorvastatin group， and high- and medium-dose BBR groups showed a significant reduction in AS plaque area （P<0.05， P<0.01）， significantly decreased levels of serum TC， TG， LDL-C， IL-6， TNF-α， ROS， and aortic Wnt5a distribution and protein expression （P<0.05， P<0.01）， and significantly increased levels of serum HDL-C， SOD， Beclin1， LC3Ⅱ， and aortic NPC1 distribution and protein expression （P<0.05， P<0.01）. There was no statistically significant difference in the above indicators between the atorvastatin group and the medium-dose BBR group. ConclusionBBR can competitively bind to Wnt5a to activate NPC1 expression， upregulate lipophagy levels， reduce blood lipids， and inhibit the release of inflammatory mediators and oxidative stress damage， thereby exerting a preventive and therapeutic effect on AS.

Dihydromyricetin reduces lipid accumulation in LO2 cells via AMPK/mTOR-mediated lipophagy pathway and inhibits HepG2 cell proliferation in vitro / 南方医科大学学报

OBJECTIVE@#To explore the mechanism underlying the hepatoprotective effect of dihydromyricetin (DMY) against lipid accumulation in light of the lipophagy pathway and the inhibitory effect of DMY on HepG2 cell proliferation.@*METHODS@#LO2 cells were cultured in the presence of 10% FBS for 24 h and treated with 100 μg/mL DMY, or exposed to 50% FBS for 24 h followed by treatment with 50, 100, or 200 μg/mL DMY; the cells in recovery group were cultured in 50% FBS for 24 h and then in 10% FBS for another 24 h. Oil red O staining was used to observe the accumulation of lipid droplets in the cells, and the levels of TC, TG, and LDL and activities of AST, ALT and LDH were measured. The expression of LC3 protein was detected using Western blotting. AO staining and transmission electron microscopy were used to determine the numbers of autophagolysosomes and autophagosomes, respectively. The formation of autophagosomes was observed with MDC staining, and the mRNA expression levels of LC3, ATG7, AMPK, mTOR, p62 and Beclin1 were determined with q-PCR. Flow cytometry was performed to analyze the effect of 50, 100, and 200 μg/mL DMY on cell cycle and apoptosis of HepG2 cells; DNA integrity in the treated cells was examined with cell DNA fragmentation test.@*RESULTS@#DMY treatment and pretreatment obviously inhibited lipid accumulation and reduced the levels of TC, TG, LDL and enzyme activities of AST, ALT and LDH in LO2 cells (P < 0.05). In routinely cultured LO2 cells, DMY significantly promoted the formation of autophagosomes and autophagolysosomes and upregulated the expression of LC3 protein. DMY obviously attenuated high FBS-induced inhibition of autophagosome formation in LO2 cells, up- regulated the mRNA levels of LC3, ATG7, Beclin1 and AMPK, and downregulated p62 and mTOR mRNA levels (P < 0.05 or 0.01). In HepG2 cells, DMY caused obvious cell cycle arrest, inhibited cell proliferation, and induced late apoptosis and DNA fragmentation.@*CONCLUSION@#DMY reduces lipid accumulation in LO2 cells by regulating the AMPK/ mTOR-mediated lipophagy pathway and inhibits the proliferation of HepG2 by causing cell cycle arrest and promoting apoptosis.

Effects of Rab7 gene up-regulation on renal fibrosis induced by unilateral ureteral obstruction

Rab7, an important member of the Rab family, is closely related to autophagy, endocytosis, apoptosis, and tumor suppression but few studies have described its association with renal fibrosis. In the early stage, our group studied the effects of Rab7 on production and degradation of extracellular matrix in hypoxic renal tubular epithelial cells. Because cell culture in vitro is different from the environment in vivo, it is urgent to understand the effects in vivo. In our current study, we established a renal fibrosis model in Rab7-knock-in mice (prepared by CRISPR/Cas9 technology) and wild type (WT) C57BL/6 mice using unilateral ureteral obstruction (UUO). Seven and 14 days after UUO, the expression of the Rab7 protein in WT mice, as well as the autophagic activity, renal function, and the degree of renal fibrosis in WT and Rab7-knock-in mice were examined by blood biochemical assay, hematoxylin-eosin and Masson staining, immunohistochemistry, and western blotting. We found that the Rab7 expression in WT mice increased over time. Furthermore, the autophagic activity constantly increased in both groups, although it was higher in the Rab7-knock-in mice than in the WT mice at the same time point. Seven days after UUO, the degree of renal fibrosis was milder in the Rab7-knock-in mice than in the WT mice, but it became more severe 14 days after surgery. Similar results were found for renal function. Therefore, Rab7 suppressed renal fibrosis in mice initially, but eventually it aggravated fibrosis with the activation of autophagy.

mTORC1 signaling in hepatic lipid metabolism

The mechanistic target of rapamycin (mTOR) signaling pathway regulates many metabolic and physiological processes in different organs or tissues. Dysregulation of mTOR signaling has been implicated in many human diseases including obesity, diabetes, cancer, fatty liver diseases, and neuronal disorders. Here we review recent progress in understanding how mTORC1 (mTOR complex 1) signaling regulates lipid metabolism in the liver.

The Role of Macrophage Lipophagy in Reverse Cholesterol Transport

Macrophage cholesterol efflux is a central step in reverse cholesterol transport, which helps to maintain cholesterol homeostasis and to reduce atherosclerosis. Lipophagy has recently been identified as a new step in cholesterol ester hydrolysis that regulates cholesterol efflux, since it mobilizes cholesterol from lipid droplets of macrophages via autophagy and lysosomes. In this review, we briefly discuss recent advances regarding the mechanisms of the cholesterol efflux pathway in macrophage foam cells, and present lipophagy as a therapeutic target in the treatment of atherosclerosis.