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Astragalus polysaccharide stimulates glucose uptake in L6 myotubes through AMPK activation and AS160/TBC1D4 phosphorylation.
Acta Pharmacol Sin. 2013 Jan; 34(1):137-45.AP

Abstract

AIM

To establish the mechanism responsible for the stimulation of glucose uptake by Astragalus polysaccharide (APS), extracted from Astragalus membranaceus Bunge, in L6 myotubes in vitro.

METHODS

APS-stimulated glucose uptake in L6 myotubes was measured using the 2-deoxy-[(3)H]-D-glucose method. The adenine nucleotide contents in the cells were measured by HPLC. The phosphorylation of AMP-activated protein kinase (AMPK) and Akt substrate of 160 kDa (AS160) was examined using Western blot analysis. The cells transfected with 4P mutant AS160 (AS160-4P) were constructed using gene transfer approach.

RESULTS

Treatment of L6 myotubes with APS (100-1600 μg/mL) significantly increased glucose uptake in time- and concentration-dependent manners. The maximal glucose uptake was reached in the cells treated with APS (400 μg/mL) for 36 h. The APS-stimulated glucose uptake was significantly attenuated by pretreatment with Compound C, a selective AMPK inhibitor or in the cells overexpressing AS160-4P. Treatment of L6 myotubes with APS strongly promoted the activation of AMPK. We further demonstrated that either Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ) or liver kinase B1 (LKB1) mediated APS-induced activation of AMPK in L6 myotubes, and the increased cellular AMP: ATP ratio was also involved. Treatment of L6 myotubes with APS robustly enhanced the phosphorylation of AS160, which was significantly attenuated by pretreatment with Compound C.

CONCLUSION

Our results demonstrate that APS stimulates glucose uptake in L6 myotubes through the AMP-AMPK-AS160 pathway, which may contribute to its hypoglycemic effect.

Authors+Show Affiliations

Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Hubei Provincial Key Laboratory of Allergy and Immune-Related Diseases, Wuhan, China.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23103623

Citation

Liu, Jian, et al. "Astragalus Polysaccharide Stimulates Glucose Uptake in L6 Myotubes Through AMPK Activation and AS160/TBC1D4 Phosphorylation." Acta Pharmacologica Sinica, vol. 34, no. 1, 2013, pp. 137-45.
Liu J, Zhang JF, Lu JZ, et al. Astragalus polysaccharide stimulates glucose uptake in L6 myotubes through AMPK activation and AS160/TBC1D4 phosphorylation. Acta Pharmacol Sin. 2013;34(1):137-45.
Liu, J., Zhang, J. F., Lu, J. Z., Zhang, D. L., Li, K., Su, K., Wang, J., Zhang, Y. M., Wang, N., Yang, S. T., Bu, L., & Ou-Yang, J. P. (2013). Astragalus polysaccharide stimulates glucose uptake in L6 myotubes through AMPK activation and AS160/TBC1D4 phosphorylation. Acta Pharmacologica Sinica, 34(1), 137-45. https://doi.org/10.1038/aps.2012.133
Liu J, et al. Astragalus Polysaccharide Stimulates Glucose Uptake in L6 Myotubes Through AMPK Activation and AS160/TBC1D4 Phosphorylation. Acta Pharmacol Sin. 2013;34(1):137-45. PubMed PMID: 23103623.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Astragalus polysaccharide stimulates glucose uptake in L6 myotubes through AMPK activation and AS160/TBC1D4 phosphorylation. AU - Liu,Jian, AU - Zhang,Jing-fang, AU - Lu,Jin-zhi, AU - Zhang,De-ling, AU - Li,Ke, AU - Su,Ke, AU - Wang,Jing, AU - Zhang,Ye-min, AU - Wang,Nian, AU - Yang,Si-Tu, AU - Bu,Lang, AU - Ou-Yang,Jing-ping, Y1 - 2012/10/29/ PY - 2012/10/30/entrez PY - 2012/10/30/pubmed PY - 2013/11/19/medline SP - 137 EP - 45 JF - Acta pharmacologica Sinica JO - Acta Pharmacol. Sin. VL - 34 IS - 1 N2 - AIM: To establish the mechanism responsible for the stimulation of glucose uptake by Astragalus polysaccharide (APS), extracted from Astragalus membranaceus Bunge, in L6 myotubes in vitro. METHODS: APS-stimulated glucose uptake in L6 myotubes was measured using the 2-deoxy-[(3)H]-D-glucose method. The adenine nucleotide contents in the cells were measured by HPLC. The phosphorylation of AMP-activated protein kinase (AMPK) and Akt substrate of 160 kDa (AS160) was examined using Western blot analysis. The cells transfected with 4P mutant AS160 (AS160-4P) were constructed using gene transfer approach. RESULTS: Treatment of L6 myotubes with APS (100-1600 μg/mL) significantly increased glucose uptake in time- and concentration-dependent manners. The maximal glucose uptake was reached in the cells treated with APS (400 μg/mL) for 36 h. The APS-stimulated glucose uptake was significantly attenuated by pretreatment with Compound C, a selective AMPK inhibitor or in the cells overexpressing AS160-4P. Treatment of L6 myotubes with APS strongly promoted the activation of AMPK. We further demonstrated that either Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ) or liver kinase B1 (LKB1) mediated APS-induced activation of AMPK in L6 myotubes, and the increased cellular AMP: ATP ratio was also involved. Treatment of L6 myotubes with APS robustly enhanced the phosphorylation of AS160, which was significantly attenuated by pretreatment with Compound C. CONCLUSION: Our results demonstrate that APS stimulates glucose uptake in L6 myotubes through the AMP-AMPK-AS160 pathway, which may contribute to its hypoglycemic effect. SN - 1745-7254 UR - https://www.unboundmedicine.com/medline/citation/23103623/Astragalus_polysaccharide_stimulates_glucose_uptake_in_L6_myotubes_through_AMPK_activation_and_AS160/TBC1D4_phosphorylation_ L2 - http://dx.doi.org/10.1038/aps.2012.133 DB - PRIME DP - Unbound Medicine ER -