Search

Background and Purpose: Berberine, a compound from rhizome coptidis, is traditionally used to treat gastrointestinal infections, such as bacterial diarrhoea. Recently, berberine was shown to have hypoglycaemic and hypolipidaemic effects. We investigated the mechanisms by which berberine regulates hepatic lipid metabolism and energy expenditure in mice., Experimental Approach: Liver-specific SIRT1 knockout mice and their wild-type littermates were fed a high-fat, high-sucrose (HFHS) diet and treated with berberine by i.p. injection for five weeks. Mouse primary hepatocytes and human HepG2 cells were treated with berberine and then subjected to immunoblotting analysis and Oil Red O staining., Key Results: Berberine attenuated hepatic steatosis and controlled energy balance in mice by inducing autophagy and FGF21. These beneficial effects of berberine on autophagy and hepatic steatosis were abolished by a deficiency of the nutrient sensor SIRT1 in the liver of HFHS diet-fed obese mice and in mouse primary hepatocytes. SIRT1 is essential for berberine to potentiate autophagy and inhibit lipid storage in mouse livers in response to fasting. Mechanistically, the berberine stimulates SIRT1 deacetylation activity and induces autophagy in an autophagy protein 5-dependent manner. Moreover, the administration of berberine was shown to promote hepatic gene expression and circulating levels of FGF21 and ketone bodies in mice in a SIRT1-dependent manner., Conclusions and Implications: Berberine acts in the liver to regulate lipid utilization and maintain whole-body energy metabolism by mediating autophagy and FGF21 activation. Hence, it has therapeutic potential for treating metabolic defects under nutritional overload, such as fatty liver diseases, type 2 diabetes and obesity., (© 2017 The British Pharmacological Society.)

Benzylisoquinoline alkaloids (BIAs) are a type of secondary metabolite with clinical application value. (S)-stylopine is a special BIA which contains methylenedioxy bridge structures. CYP719As could catalyze the methylenedioxy bridge-formation on the A or D rings of protoberberine alkaloids, while displaying significant substrate regiospecificity. To explore the substrate preference of CYP719As, we cloned and identified five CyCYP719A candidates from Corydalis yanhusuo. Two CyCYP719As (CyCYP719A39 and CyCYP719A42) with high catalytic efficiency for the methylenedioxy bridge-formation on the D or A rings were characterized, respectively. The residues (Leu 294 for CyCYP719A42 and Asp 289 for CyCYP719A39) were identified as the key to controlling the regioselectivity of CYP719As affecting the methylenedioxy bridge-formation on the A or D rings by homology modeling and mutation analysis. Furthermore, for de novo production of BIAs, CyCYP719A39, CyCYP719A42, and their mutants were introduced into the (S)-scoulerine-producing yeast to produce 32 mg/L (S)-stylopine. These results lay a foundation for understanding the structure-function relationship of CYP719A-mediated methylenedioxy bridge-formation and provide yeast strains for the BIAs production by synthetic biology. [ABSTRACT FROM AUTHOR]