AMP-activated protein kinase (AMPK) is involved in the development and progression of tumors including hepatocellular carcinoma (HCC). However, studies on AMPK and tumorigenesis were largely based on experiments in vitro or tumor xenografts model. Here, we introduce a liver-specific AMPKα1 knockout mice model, which is achieved by Alb-Cre recombinase system. The expression of AMPKα1 in the liver of AMPKα1-/--Alb-Cre mice is absent. AMPKα1 knockout in the liver does not affect the growth and histological structure of mouse liver. This model provides a favorable tool to the study of the roles of AMPKα1 in liver metabolism or tumorigenesis.
Objective To investigate the mechanism of AMP-activated protein kinase (AMPK) in hepatic ischemia-reperfusion injury (HIRI). Methods ① Grouping. Forty-two mice were randomly divided into Sham group, 4 ischemia reperfusion (IR) group of different times (2, 6, 12, and 24 h), Compound C group, and Compound C+repamycin (Rapa) group, each group enrolled in 6 mice. Compound C group: mice were modeled at 1 h after intraperitoneal injection of Compound C (25 mg/kg). Compound C+Rapa group: mice were modeled at 1 h after intraperitoneal injection of rapamycin (1 mg/kg) and Compound C (25 mg/kg). Mice of 4 IR groups, Compound C group, and Compound C+Rapa group were used to prepare HIRI model. Mice of Sham group were treated only for laparotomy, freeing the first portal hepatis and closing peritoneal. ② To filter the best IR time. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum of mice in Sham group and IR groups of 4 different reperfusion time points were measured. The pathological changes of liver tissues were observed by HE staining, and the expressions of related proteins in liver tissue of mice were detected by Western blot. Considering the results of blood biochemical test, HE staining, and Western blot together to determine the best IR point. ③ The exploration of signal pathway for AMPK. The expressions of proliferating cell nuclear antigen (PCNA) were observed by immunohistochemical staining in the liver tissues of IR-12 h group, Compound C group (12 h after IR) and compound C+Rapa group (12 h after IR). The mitochondrial damage was observed by rhodamine 123 staining, and the apoptotic status of liver cells was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay (TUNEL). Results ① The 12 h after IR was the best observation time point. Compared with IR-12 h group, the levels of ALT and AST in Sham group, IR-2, 6, and 24 h groups were lower (P<0.05). HE staining showed that liver tissue destruction in IR-12 h group was the most severe. Western blot showed that, expressions of AMPKα, phosphorylated adenylate activated protein kinase α (p-AMPKα), Nip3-like protein X (Nix), BCL-2 homologous water-soluble protein (Bax), as well as ratio of autophagy microtubule-associated protein light chain 3 (LC3)Ⅱto LC3Ⅰof Sham group, IR-2, 6, and 24 h group were all lower than those of IR-12 h group (P<0.05), but the expressions of phosphorylated mammalian target of Rapa (p-mTOR) of Sham group, IR-2, 6, and 24 h group were all higher (P<0.05). Therefore, 12 h after IR was the best time to observe. ② Compared with IR-12 h group, the expression level of PCNA protein in liver tissue of Compound C group was lower (P<0.05), the mitochondrial luminescence intensity was weaker and the apoptotic cells were more. Compared with Compound C group, the expression of PCNA protein in the liver tissue of the Compound C+Rapa group was higher (P<0.05), the mitochondrial intensity was stronger and the apoptotic cells were less. ③ Compared with IR-12 h group, the expressions of Nix and p-AMPKα, and ratio of LC3Ⅱ to LC3Ⅰ in liver tissue of Compound C group decreased (P<0.05), while the expressions of p-mTOR, Caspase-3, and Cleaved Caspase-3 increased (P<0.05). Compared with Compound C group, the expressions of p-AMPKα and Nix in the liver tissue of Compound C+Rapa group increased (P<0.05), while the expressions of p-mTOR, Caspase-3, and Cleaved Caspase-3 decreased (P<0.05). Conclusion During the HIRI in mouse, AMPK regulates mitophagy and apoptosis through the mTOR/Nix pathway.
Objective To investigate the effects of wedelolactone (WEL) on lipopolysaccharide (LPS)-induced pyroptosis of alveolar epithelial cells and AMP-activated protein kinase/nucleotide binding oligomeric domain like receptor 3 (NLRP3)/cysteinyl aspartate specific proteinase-1 (Caspase-1) signaling pathway. Methods Human lung epithelial cells BEAS-2B were treated with 5 - 200 μmol/L wedelolactone, and cell activity was detected using MTT assay. The alveolar epithelial cells were divided into control group, lipopolysaccharide group (LPS group), 10 μmol/L wedelolactone group (WEL-L group), 20 μmol/L wedelolactone group (WEL-M group), 40 μmol/L wedelolactone group (WEL-H group), 40 μmol/L wedelolactone+10 μmol/L AMPK inhibitor Compound C group (WEL-H+Compound C group), and 20 μmol/L Caspase-1 inhibitor Z-YVAD-FMK group (Z-YVAD-FMK group). Transmission electron microscopy was applied to observe the microstructure of cells. ELISA was applied to detect levels of inflammatory factors such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-8 (IL-8). Immunofluorescence was applied to detect Caspase-1 and gasdermin family proteins (DGSDMD). Western blot was applied to detect protein expression levels of AMPK, NLRP3, and Caspase-1. Results Wedelolactone concentrations of 10, 20 and 40 μmol/L were selected for follow-up experiments. Compared with Control group, LPS group showed decreased cell activity, severe damage, cell contraction, mitochondrial ridge breakage and decreased number, increased levels of TNF-α, IL-1β, IL-8 and GSDMD, NLRP3, Caspase-1 expression, and decreased p-AMPK/AMPK expression (P<0.05). Wedelolactone treatment could significantly improve LPS-induced pyrosis of alveolar epithelial cells (P<0.05). Compound C could partially reverse the effect of wedelactone on LPS-induced pyrodeath of alveolar epithelial cells (P<0.05). Z-YVAD-FMK treatment also significantly improved LPS-induced pyroptosis of alveolar epithelial cells (P<0.05). Conclusion Wedelolactone can inhibit LPS-induced pyroptosis of pulmonary alveolar epithelial cells by inhibiting AMPK/NLRP3/Caspase-1 signaling pathway.