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Logo of actahistAuthor GuidelinesHomepageActa Histochemica et Cytochemica
 
Acta Histochem Cytochem. 2006 December 28; 39(6): 155–161.
Published online 2006 December 6. doi:  10.1267/ahc.06024
PMCID: PMC1779948
Apical Localization of Sodium-Dependent Glucose Transporter SGLT1 is Maintained by Cholesterol and Microtubules
Takeshi Suzuki,1 Toshiyuki Matsuzaki,1 Haruo Hagiwara,1 Takeo Aoki,1 Yukiko Tajika-Takahashi,1 and Kuniaki Takata1
1Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371–8511, Japan
Correspondence to: Takeshi Suzuki, Ph.D., Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, Showa-machi 3–39–22, Maebashi, Gunma 371–8511, Japan. E-mail: suzutake/at/showa.gunma-u.ac.jp
Received October 2, 2006; Accepted October 23, 2006.
Abstract
A GFP-labeled sodium-dependent glucose transporter SGLT1 (SGLT-GFP) was transfected into MDCK cells. SGLT-GFP was localized at the apical membrane in confluent cells. When cellular cholesterol was depleted by methyl-β-cyclodextrin (MβCD) treatment, the localization of SGLT-GFP gradually switched from apical to whole plasma membrane. Time-lapse microscopy revealed that the effect of MβCD appeared within 30 min, and that the transition of SGLT-GFP to the whole plasma membrane was completed within 2 hr after the administration. Immunofluorescence microscopy revealed that the tight junction framework remained steady during this process. The effect of MβCD on SGLT-GFP localization was counter­balanced by the addition of cholesterol into the culture medium. Disruption of microtubules by colcemid also perturbed SGLT-GFP localization. SGLT-GFP localized to the whole plasma membrane by colcemid treatment, and apical localization was restored within 1 hr after ­removal of colcemid. Inhibition of protein synthesis by cycloheximide had no effect on the transition of SGLT-GFP induced by the MβCD or colcemid. These results indicated that the apical localization of SGLT-GFP is maintained by cellular cholesterol and microtubules, possibly with an apical recycling machinery.
Keywords: SGLT, apical membrane, cell polarity, cholesterol, microtubule
Articles from Acta Histochemica et Cytochemica are provided here courtesy of
Japan Society of Histochemistry and Cytochemistry