Regulation of SGLT expression and localization through Epac/PKA-dependent caveolin-1 and F-actin activation in renal proximal tubule cells.
This study demonstrated that exchange proteins directly activated by cAMP (Epac) and protein kinase A (PKA) by 8-bromo (8-Br)-adenosine 3',5'-cyclic monophosphate (cAMP) stimulated [(14)C]-α-methyl-D-glucopyranoside (α-MG) uptake through increased sodium-glucose cotransporters (SGLTs) expression and translocation to lipid rafts in renal proximal tubule cells (PTCs). In PTCs, SGLTs were colocalized with lipid raft caveolin-1 (cav-1), disrupted by methyl-β-cyclodextrin (MβCD). Selective activators of Epac or PKA, 8-Br-cAMP, and forskolin stimulated expressions of SGLTs and α-MG uptake in PTCs. In addition, 8-Br-cAMP-induced PKA and Epac activation increased phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and nuclear factor kappa B (NF-κB), which were involved in expressions of SGLTs. Furthermore, 8-Br-cAMP stimulated SGLTs translocation to lipid rafts via filamentous actin (F-actin) organization, which was blocked by cytochalasin D. In addition, cav-1 and SGLTs stimulated by 8-Br-cAMP were detected in lipid rafts, which were blocked by cytochalasin D. Furthermore, 8-Br-cAMP-induced SGLTs translocation and α-MG uptake were attenuated by inhibition of cav-1 activation with cav-1 small interfering RNA (siRNA) and inhibition of F-actin organization with TRIO and F-actin binding protein (TRIOBP). In conclusion, 8-Br-cAMP stimulated α-MG uptake via Epac and PKA-dependent SGLTs expression and trafficking through cav-1 and F-actin in PTCs.
Department of Veterinary Physiology, Chonnam National University, Gwangju, Republic of Korea.
Yu Jin
YJ
Lee
Mi Ok
MO
Kim
Jung Min
JM
Ryu
Ho Jae
HJ
Han
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000199:Actins / Q000378:metabolism*; D000818:Animals; D051242:Caveolin 1 / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D008757:Methylglucosides / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D011817:Rabbits; D051247:Sodium-Glucose Transport Proteins / Q000378:metabolism*
D000199:Actins; D051242:Caveolin 1; D020662:Guanine Nucleotide Exchange Factors; D008757:Methylglucosides; D051247:Sodium-Glucose Transport Proteins; D015124:8-Bromo Cyclic Adenosine Monophosphate; C027020:methylglucoside; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases