Abstract: Objective To examine the effects of over-expression Hsp70 on the glucose metabolism in C2C12 cells. Methods C2C12 cells were divided into two groups: transfected group and normal control. Hsp70 gene was amplified from pAT153 plasmids and then cloned into pTRE2hyg vector. After the transfection of recombinant plasmids of pTRE2hyg- Hsp70 into the C2C12 cells, the expression of Hsp70 was examined by Western blot and the C2C12 cell line of up-regulated Hsp70 was established. Glucose consumption and glucose uptake were measured by the glucose oxidase method and 3H-labeled glucose respectively at 3 and 7 days after cellular differentiation in two groups. Changes in lactate production were determined by biochemical analyzer. In addition, activities of enzymes involved in glycolysis (phosphofructokinase, PFK; lactate dehydrogenase, LDH; hexokinase, HK; pyruvate kinase, PK) and the intracellular ATP level were evaluated by colorimetry in C2C12 cells. The expression of plasma membrane Glut4 in protein level was measured by Western-blot. Results Compared with controls, the glucose consumption, glucose uptake and lactate excretion were significantly elevated in cells expressing up-regulated Hsp70 (p<0.01) at 3 and 7 days after cellular differentiation. The activities of enzymes involved in glycolysis ( PFK, LDH, HK, PK ) and the intracellular ATP level were significantly increased (p<0.01) in the transfected C2C12 cells. In addition, the expression of plasma membrane Glut4 in protein level was increased in transfected C2C12 cells (p<0.05) . Conclusion Hsp70 can promote glucose uptake by increasing the expression of plasma membrane Glut4 in C2C12 cells. And Hsp70 can also increase the glycolytic capacity by increasing the activities of glycolytic enzymes in C2C12 cells.

Key words: heat shock protein70, skeletal muscle cells, glucose uptake, glycolysis, Glut4