The C-terminal tail of CRTH2 is a key molecular determinant that constrains Gα i and downstream signaling cascade activation

Ralf Schröder, Nicole Merten, Jesper Mosolff Mathiesen, Lene Martini, Anamarija Kruljac-Letunic, Friederike Krop, Andree Blaukat, Ye Fang, Elizabeth Tran, Trond Ulven, Christel Drewke, Jennifer Whistler, Leonardo Pardo, Jesús Gomeza, Evi Kostenis

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47 Scopus citations

Abstract

Prostaglandin D 2 activation of the seven-transmembrane receptor CRTH2 regulates numerous cell functions that are important in inflammatory diseases, such as asthma. Despite its disease implication, no studies to date aimed at identifying receptor domains governing signaling and surface expression of human CRTH2. We tested the hypothesis that CRTH2 may take advantage of its C-tail to silence its own signaling and that this mechanism may explain the poor functional responses observed with CRTH2 in heterologous expression systems. Although the C terminus is a critical determinant for retention of CRTH2 at the plasma membrane, the presence of this domain confers a signaling-compromised conformation onto the receptor. Indeed, a mutant receptor lacking the major portion ofits C-terminal tail displays paradoxically enhanced Gα i and ERK1/2 activation despite enhanced constitutive and agonist-mediated internalization. Enhanced activation of Gα i proteins and downstream signaling cascades is probably due to the inability of the tail-truncated receptor to recruit β-arrestin2 and undergo homologous desensitization. Unexpectedly, CRTH2 is not phosphorylated upon agonist-stimulation, a primary mechanism by which GPCR activity is regulated. Dynamic mass redistribution assays, which allow label-free monitoring of all major G protein pathways in real time, confirm that the C terminus inhibits Gα i signaling of CRTH2 but does not encode G protein specificity determinants. We propose that intrinsic CRTH2 inhibition by its C terminus may represent a rather unappreciated strategy employed by a GPCR to specify the extent of G protein activation and that this mechanism may compensate for the absence of the classical phosphorylation-dependent signal attenuation.

Original languageEnglish (US)
Pages (from-to)1324-1336
Number of pages13
JournalJournal of Biological Chemistry
Volume284
Issue number2
DOIs
StatePublished - Jan 9 2009
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Schröder, R., Merten, N., Mathiesen, J. M., Martini, L., Kruljac-Letunic, A., Krop, F., Blaukat, A., Fang, Y., Tran, E., Ulven, T., Drewke, C., Whistler, J., Pardo, L., Gomeza, J., & Kostenis, E. (2009). The C-terminal tail of CRTH2 is a key molecular determinant that constrains Gα i and downstream signaling cascade activation. Journal of Biological Chemistry, 284(2), 1324-1336. https://doi.org/10.1074/jbc.M806867200