Nrf2 signalling pathway and autophagy impact on the preventive effect of green tea extract against alcohol-induced liver injury.

OBJECTIVES: To explore the potential molecular mechanism underlying the effect of green tea extract (TE), rich in tea polyphenols (TPs), on improving alcohol-induced liver injury. METHODS: Mice were intragastrically treated with 50% (v/v) alcohol administration (15 ml/kg BW) with or without three doses of TE (50, 120 and 300 mg TPs/kg BW) daily for 4 weeks, and biological changes were tested. KEY FINDINGS: The TE improved the functional and histological situations in the liver of the mice accepted alcohol administration, including enzymes for alcohol metabolism, oxidative stress and lipid accumulation. Interestingly, the TE increased the nuclear translocation of nuclear factor erythroid-2-related factor 2 (Nrf2), with the decreasing expression of kelch-like ECH-associated protein 1 (Keap1), indicating the association between the effect of TE with Nrf2-mediated antioxidant signalling. Moreover, the TE restored the activity of autophagy, showing as lifted Beclin-1 expression, LC3B-II/LC3B-I ratio, and decreased p62 expression. Importantly, all these effects were dose-dependent. CONCLUSIONS: These findings provide a new notion for the first time that the TE preventing against alcohol-induced liver injury is closely related to accelerated metabolism of alcohol and relieved oxidative stress, which is associated with Nrf2 signalling activation and autophagy restoration, thus the reduction of lipid accumulation in liver.

A novel zinc finger protein Zfp637 behaves as a repressive regulator in myogenic cellular differentiation.

Zinc finger proteins have been implicated as transcription factors in the differentiation and development of cells and tissues in higher organisms. The classical C2H2 zinc finger motif is one main type of motif of zinc finger proteins. Our previous studies have shown that Zfp637, which comprises six consecutively typical and one atypical C2H2 zinc finger motifs, is highly expressed in undifferentiated or poorly differentiated cell lines, but is moderately or slightly expressed in normal tissues. We have also demonstrated that Zfp637 can promote cell proliferation. However, its role in the regulation of cell differentiation remains unknown. We report here that endogenous Zfp637 as well as mTERT is expressed in proliferating C2C12 myoblasts and that their expression is downregulated during myogenic differentiation. Constitutive expression of Zfp637 in C2C12 myoblasts increased mTERT expression and telomerase activity, and promoted the progression of the cell cycle and cell proliferation. By contrast, endogenous repression of Zfp637 expression by RNA interference downregulated the mTERT gene and the activity of telomerase, and markedly reduced cell proliferation. Overexpression of Zfp637 also inhibited the expression of myogenic differentiation-specific genes such as MyoD and myogenin, and prevented C2C12 myoblast differentiation. Our results suggest that Zfp637 inhibits muscle differentiation through a defect in the cell cycle exit by potentially regulating mTERT expression in C2C12 myoblasts. This may provide a new research line for studying muscle differentiation.

[Construction of eukaryotic expression plasmid for a novel zinc finger protein gene Zfp637 and its effect on breast carcinoma cell EMT6].

OBJECTIVE: To construct the eukaryotic expression plasmid and establish stably transfected cell line, which contained the code gene of zinc finger protein637 (Zfp637), and to observe the effect of Zfp637 gene to the proliferation of tumor cells. METHODS: The Zfp637 DNA was amplified from the template of normal spleen tissue cDNA and cloned into the eukaryotic expression vector pEGFP-C3. The recombinant plasmid, named as pEGFP-Zfp637, was determined by restriction enzyme and sequencing analyses. Next the pEGFP-Zfp637 recombinant plasmid was transferred into mouse breast carcinoma EMT6 cells with lipofectamine 2000, and the stably transfected cells were selected by G418 (named Zfp637-EMT6). The growth condition of cells was observed, and subcellular localization of Zfp637 gene was located by fluorescence microscope at the same time. The Zfp637 mRNA expression in the transfected cells was detected by RT-PCR, and the proliferation of such cells was measured by MTT. RESULTS: The analysis confirmed that the recombinant pEGFP-Zfp637 contained the Zfp637 full-length cDNA. The Zfp637 mRNA was over-expressed stably in Zfp637-EMT6. The growth of Zfp637-EMT6 was increased obviously when compared with the negative control group and blank group. CONCLUSION: The recombinant pEGFP-Zfp637 has been constructed successfully, and the expression of the Zfp637 gene can promote the proliferation of cells. This recombinant eukaryotic expression plasmid can be used in advanced studies in the biological effects of Zfp637 and anti-tumor gene therapy.

[Effect of total flavonoids of Hippophae rhamnoides L. on the expression of MCP-1 in aorta of spontaneously hypertensive rats].

OBJECTIVE: To study the effects of total flavonoids of Hippophae rhamnoides L. (TFH) on the expression of monocyte chemoattractant protein (MCP-1) in aorta of Spontaneously Hypertensive Rats (SHR) and to study the relationship of expression of MCP-1 in aorta and intimal medial thickness (IMT) of aorta. METHODS: Twelve-week-old male SHR (n=12) were randomly devided into three groups to receive TFH [30 mg/(kg x d), n=4], Enalapril [10 mg/(kg x d), n= 4] and Hydrochlorothiazide [25 mg/(kg x d), n=4] for 12 weeks, respectively. Another 4 SHR and 4 WKY which receive placebo served as positive control group and negative control group. The systolic blood pressure (SBP), intimal medial thickness and inside diameter of aorta of the rats were measured. The expression of MCP-1 in aorta was examined by real-time PCR and immunohistochemistry and the concentration of serum MCP-1 protein by ELSA. RESULTS: Twelve weeks later, systolic blood pressure in TFH was significantly decreased, compared with that in Enalapril and Hydrochlorothiazide without statistical differences. TFH markedly reduced the intimal medial thickness of aorta and expression of MCP-1 in aorta, similar with Enalapril, stronger than Hydrochlorothiazide. CONCLUSION: TFH can markedly decrease SBP of SHR and the decrease value of the TFH group was similar with that of the Enalapril and Hydrochlorothiazide group. TFH may inhibit the expression of MCP-1 in aorta and intimal medial thickness of aorta beyond BP Lowering effect. The effect of THF on the expression of MCP-1 and intimal medial thickness of aorta was similar with Enalapril. TFH may through inhibite the expression of MCP-1 in aorta to reduce the intimal medial thickness of aorta and protect hypertensive injury in target organs.