Kidney Week

Abstract: FR-PO329

Succinate Transport Is Mediated and Regulated by the slc26a6/NaDC-1 Transporters

Session Information

• Hypertension and CVD: Mechanisms - I
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Hypertension and CVD

• 1403 Hypertension and CVD: Mechanisms

Authors

• Khamaysi, Ahlam, Ben Gurion university of the Negev, Beer Sheva, Israel

Ahlam Khamaysi,

• Ohana, Ehud, Ben Gurion university of the Negev, Beer Sheva, Israel

Ehud Ohana,

Background

The slc26a6/NaDC-1 system controls citrate absorption from the urinary lumen. Urinary citrate chelates free Ca²⁺ thus protecting against Ca²⁺-oxalate crystallization. Since the slc26a6/NaDC-1 complex mediates and regulates both citrate and succinate transport, a major question that we asked here is whether the same mechanism controls succinate homeostasis and which molecular determinants mediate slc26a6-NaDC-1 interaction and regulation.

Methods

We monitored protein-protein interaction by coimmunoprecipiatation. Succinate transport was monitored using electrophysiological measurements.

Results

Our structural modeling confirmed by mutational analysis identified the slc26a6/NaDC-1 interacting surfaces that mediate regulation of NaDC-1 by slc26a6. To test our model, we monitored the effects of slc26a6 (E613A) and NaDC-1(K107A, R108A) on NaDC-1–slc26a6 interaction by co-immunoprecipitation (coIP). The slc26a6(E613A) mutant showed reduced interaction with NaDC-1 and reduced inhibition of NaDC-1 activity, assayed as Na+-dependent succinate currents .Although expression of slc26a6 was not affected by the (E613A) mutation, slc26a6(E613A) had ~30% lower Cl^-/oxalate exchange activity. The role of NaDC-1(K107) and NaDC-1(R108) in the NaDC-1–slc26a6 interaction is shown. While NaDC-1(R108A) was inactive (not shown), NaDC-1(K107A) retained its activity. Importantly, however, the interaction between NaDC-1(K107A) and slc26a6 was reduced and NaDC-1(K107A) was not inhibited by slc26a6, which strongly inhibits WT NaDC-1.

Conclusion

These results suggest that NaDC-1-mediated succinate transport is controlled by the interaction between the two transporters, and that their interaction is mediated by E613 at the slc26a6-STAS domain and K107 at the NaDC-1 H4c region.