Paper Information

Title: 

STIMULATION OF THE INTESTINAL PHOSPHATE TRANSPORTER SLC34A2 BY THE PROTEIN KINASE MTOR

Type: POSTER
Author(s): SHOJAEIFARD M.,LANG F.
 
 
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2009Volume 19
 
 
Abstract: 

Adequate phosphate homeostasis is of critical importance for a wide variety of functions including bone mineralization and energy metabolism. Phosphate balance is a function of intestinal absorption and renal elimination, which is both under tight hormonal control. Intestinal phosphate absorption, is accomplished by the Na+, phosphate cotransporter NaPiIIb (SLC34A2).Signaling mechanisms mediating hormonal regulation of SLC34A2 are incompletely understood. The mammalian target of rapamycin (mTOR) is a kinase regulating a variety of nutrient transporters. The present experiments explored whether mTOR regulates the activity of SLC34A2. In Xenopus oocytes expressing SLC34A2 but not in water injected oocytes phosphate (1mM) induced a current (Ip) which was significant enhanced by coexpression of mTOR. Perincubation of the oocytes for 24h with rapamycin (50nM) did not significantly affect Ip in the absence of TOR but virtually abolished the increase of Ip following coexpression of TOR. The wild type serum and glucocorticoid inducible kinase SGK1 and the constitutively active S422DSGK1 similarly stimulated Ip ,an effect again reserved by rapamycin Coexpression of the inactive mutant of the serum and glucocorticoid inducible kinase K119NSGK1 significantly decreased Ip and abrogated the stimulating effect of TOR on Ip.
In conclusion, mTOR and SGK1 cooperate in the stimulation of the intestinal phosphate transporter SLC34A2.

 
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