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Abstract: TH-PO726

MAP17 and SGLT2 Interaction in Cellular Models and Human Kidney Specimen

Session Information

Category: Genetic Diseases of the Kidney

  • 1002 Genetic Diseases of the Kidney: Non-Cystic

Authors

  • Calado, Joaquim T., NOVA Medical School; Faculdade de Ciencias Medicas, Lisbon, LIsbon, Portugal
  • Santos, Ana, Hospital Curry Cabral, Lisbon, Portugal
  • Aires, Ines, Hospital Curry Cabral, Lisbon, Portugal
  • Ramalho, Jose S., NOVA Medical School, Lisbon, Portugal
  • Nolasco, Fernando E B, Hospital Curry Cabral, Lisbon, Portugal

Group or Team Name

  • ToxOmics
Background

Mutations in SGLT2, a Na/coupled glucose transporter of the early proximal tubule, are responsible for Familial Renal Glucosuria (FRG), and SGLT2 pharmacological inhibition has become a promising new therapy in type 2 Diabetes Mellitus.
MAP17 was recently identified by means of expression cloning as an accessory protein for SGLT2 activity and mutations in MAP17 coding gene were found in a SGLT2 negative FRG individual.
However, the way MAP17 promotes SGLT2 activity is unknown. In this work we investigated the hypothesis that MAP17 is a binding partner for SGLT2 and that both proteins interact and dimerize.

Methods

We engineered a N-terminal V5 tagged SGLT2 plasmid and coexpressed together with a HA tagged MAP17 construct in HEK293 cells. We assayed the interaction of both proteins in vitro by immunofluorescence and immunochemistry techniques. In addition, we performed histological examination and immunofluorescence observations in human normal kidney sections to evaluate MAP17 and SGLT2 expression in the kidney.

Results

In HEK293 cells cotransfected with both constructs, MAP17 and SGLT2 were shown to colocalize in a perinuclear and cytoplasmic vesicular staining. In addition, MAP17 coimmunoprecipitated with anti V5 goat antibody only in the presence of V5-SGLT2 construct (fig.1). Finally, SGLT2 and MAP17 largely overlap in their abundance at the brush border of proximal tubule epithelial cells (fig. 2).

Conclusion

We have shown that SGLT2 and MAP17, when overexpressed, interact in vitro and, likewise, under constitutive expression in the kidney, they also overlap their abundance in the proximal tubule. This interaction provides the biochemical foundation for the physiological observation that MAP17 is a necessary activator of SGLT2.