Abstract | BACKGROUND: METHODOLOGY/FINDINGS: NPT2a was expressed alone or in combination with CFTR in X. laevis oocytes. Using the two- electrode voltage-clamp technique, the inorganic phosphate-induced current (IPi) was measured and taken as an index of NPT2a activity. The maximal IPi for NPT2a substrates was reduced when CFTR was co-expressed with NPT2a, suggesting a decrease in its expression at the oolemna. This was consistent with Western blot analysis showing reduced NPT2a plasma membrane expression in oocytes co-expressing both proteins, whereas NPT2a protein level in total cell lysate was the same in NPT2a- and NPT2a+CFTR-oocytes. In NPT2a+CFTR- but not in NPT2a-oocytes, IPi and NPT2a surface expression were increased upon PKA stimulation, whereas stimulation of Exchange Protein directly Activated by cAMP ( EPAC) had no effect. When NPT2a-oocytes were injected with NEG2, a short amino-acid sequence from the CFTR regulatory domain that regulates PKA-dependent CFTR trafficking to the plasma membrane, IPi values and NPT2a membrane expression were diminished, and could be enhanced by PKA stimulation, thereby mimicking the effects of CFTR co-expression. CONCLUSION/PERSPECTIVES: We conclude that when both CFTR and NPT2a are expressed in X. laevis oocytes, CFTR confers to NPT2a a cAMPi-dependent trafficking to the membrane. This functional interaction raises the hypothesis that CFTR may play a role in phosphate homeostasis.
|
Authors | Naziha Bakouh, Baya Chérif-Zahar, Philippe Hulin, Dominique Prié, Gérard Friedlander, Aleksander Edelman, Gabrielle Planelles |
Journal | PloS one
(PLoS One)
Vol. 7
Issue 4
Pg. e34879
( 2012)
ISSN: 1932-6203 [Electronic] United States |
PMID | 22514683
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
|
Chemical References |
- Sodium-Phosphate Cotransporter Proteins, Type IIa
- Xenopus Proteins
- Cystic Fibrosis Transmembrane Conductance Regulator
|
Topics |
- Animals
- Cystic Fibrosis Transmembrane Conductance Regulator
(metabolism)
- Female
- Oocytes
(metabolism)
- Protein Binding
- Sodium-Phosphate Cotransporter Proteins, Type IIa
(metabolism)
- Xenopus Proteins
(metabolism)
- Xenopus laevis
(metabolism)
|