Role of actin in the cAMP-dependent activation of sodium/glucose cotransporter in renal epithelial cells |
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Authors: | Akira Ikari Hitoshi Harada Kuniaki Takagi |
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Institution: | Department of Environmental Biochemistry and Toxicology, University of Shizuoka School of Pharmaceutical Sciences, 52-1 Yada, Shizuoka 422-8526, Japan |
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Abstract: | We examined whether actin filaments are involved in the cAMP-dependent activation of a high affinity sodium/glucose cotransporter (SGLT1) using epithelial expression systems. The expression of enhanced green fluorescent protein-tagged SGLT1 (EGFP-SGLT1) in Madin-Darby canine kidney (MDCK) cells was revealed by Western blotting and confocal laser microscopy. 8-Br-cAMP, a membrane permeable cAMP analog, enhanced 14C]-α-methyl glucopyranoside (14C]-AMG) uptake. Both basal and 8-Br-cAMP-elicited 14C]-AMG uptakes were inhibited by N-(2{3-(4-bromophenyl)-2-propenyl]-amino}-ethyl)-5-isoquinolinesulfonamide (H-89), a protein kinase A inhibitor, and cytochalasin D, an actin filament formation inhibitor. Furthermore, cytochalasin D inhibited the distribution of EGFP-SGLT1 at the apical surface. These results suggest that the EGFP-SGLT1 protein is functionally expressed in the apical membrane of MDCK cells, and is up-regulated by a cAMP-dependent pathway requiring intact actin filaments. |
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Keywords: | Green fluorescent protein Protein kinase A SGLT1 |
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