Background: Diabetes is the leading cause of kidney disease, with more than 36% of diabetic patients developing kidney disease. This incidence has persisted despite the availability of therapies like SGLT2 inhibitors. Glucose is reabsorbed in the kidney proximal tubule via polarized transporters: SGLT2 in the apical membrane and Glut-2 in the basolateral membrane. Previous evidence has shown that expression of SGLT2 and Glut-2 is increased in diabetic kidneys. However, how glucose affects trafficking and polarity of these transporters is unknown. Proper trafficking in proximal tubule cells is essential for polarization of plasma membrane proteins to the apical and basolateral plasma membrane domains, and efficient glucose absorption. Our objective was to determine how high glucose affects trafficking and polarization of SGLT2 and Glut-2 in proximal tubule cells. This knowledge will permit the future development of therapeutic approaches targeting glucose handling in the diabetic kidney.Hypothesis: We hypothesized that high glucose decreases polarization of SGLT2 and GLUT2 at the plasma membrane of proximal tubule cells.Methods: Renal proximal tubule epithelial cells (RPTEC) were cultured on Transwell filters for 2 weeks. Treatment with normal (5.5mM) or high (25 mM) glucose was done for the last 3 days of culture. Surface expression of SGLT2 and Glut-2 was measured by surface biotinylation at the apical or basolateral domain, followed by western blot. Surface SGLT2 and Glut-2 expression was also measured by surface biotinylation in proximal tubule suspensions from wt (healthy) and Akita (diabetic) mice.Results: We observed that in native proximal tubules from diabetic Akita mice, the surface/intracellular ratio of SGLT2 was increased from 0.00143 ± 0.00028 to 0.00333 ± 0.00033, a 133% increase. Similarly, surface Glut-2 increased from 2.202 ± 0.2352 to 3.981 ± 0.2526 or by 81% (p< 0.05). When the surface/intracellular ratio of SGLT2 and Glut-2 was measured in cultured RPTEC cells, a similar trend was observed on high glucose, however this did not reach statistical significance. Next, we tested the effect of high glucose in polarity of the transporters. We observed that high glucose abolished the apical polarity of SGLT2 from 73.54 ± 3.68% apical to 50.00 ± 4.76% apical/basolateral (p< 0.001). Glut-2 seemed to switch from 59.31 ± 3.01% basolateral (p< 0.001) on normal glucose, to 59.06 ± 6.80% apical on high glucose. However, the statistical significance only confirmed a loss of polarity.Conclusion: High glucose abolished the polarization of SGLT2 and Glut-2 in proximal tubule cells. While there was not enough evidence that high glucose increased surface expression of SGLT2 and Glut-2 in cultured proximal tubule cells, we observed a significant increase in their surface abundance in native proximal tubules from diabetic mice Funding. NIH: R35GM150570; R21DK136122 This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Jaster et al. (Fri,) studied this question.