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Discovery of a functional immunoreceptor tyrosine‐ based switch motif in a 7‐transmembrane‐spanning receptor: role in the orexin receptor OX1R‐driven apoptosis
Author(s) -
El Firar Aadil,
Voisin Thierry,
Rouyer-Fessard Christiane,
Ostuni Mariano A.,
Couvineau Alain,
Laburthe Marc
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.09-131367
Subject(s) - immunoreceptor tyrosine based activation motif , orexin , tyrosine , tyrosine phosphorylation , transmembrane protein , protein tyrosine phosphatase , phosphorylation , biology , microbiology and biotechnology , receptor , transmembrane domain , biochemistry , sh2 domain , neuropeptide
The orexin neuropeptides promote ro‐ bust apoptosis in cancer cells. We have recently shown that the 7‐transmembrane‐spanning orexin receptor OX1R mediates apoptosis through an original mecha‐ nism. OX1R is equipped with a tyrosine‐based inhibi‐ tory motif ITIM, which is tyrosine‐phosphorylated on receptor activation, allowing the recruitment and acti‐ vation of the tyrosine phosphatase SHP‐2, leading to apoptosis. We show here that another motif, immuno‐ receptor tyrosine‐based switch motif (ITSM), is present in OX1R and is mandatory for OX1R‐mediated apopto‐ sis. This conclusion is based on the following observa‐ tions: 1 ) a canonical ITSM sequence is present in the first intracellular loop of OX1R; 2 ) mutation of Y 83 to F within ITSM abolished OX1R‐mediated apop‐ tosis but did not alter orexin‐induced inositol phos‐ phate formation or calcium transient via coupling of OX1R to G q protein; 3 ) mutation of Y 83 to F further abolished orexin‐induced tyrosine phosphorylation in ITSM and subsequent recruitment of SHP‐2 by the receptor. Finally, we developed a structural model of OX1R showing that the spatial localization of phospho‐ tyrosines in ITSM and ITIM in OX1R is compatible with their interaction with the two SH2 domains of SHP‐2. These data represent the first evidence for a functional role of an ITSM in a 7‐transmembrane‐ spanning receptor.—El Firar, A., Voisin, T., Rouyer‐ Fessard, C., Ostuni, M. A., Couvineau, A., Laburthe, M. Discovery of a functional immunoreceptor tyrosine‐ based switch motif in a 7‐transmembrane‐spanning re‐ ceptor: role in the orexin receptor OX1R‐driven apop‐ tosis. FASEB J. 23, 4069 – 4080 (2009). www.fasebj.org