ANKRD13C acts as a molecular chaperone for G protein-coupled receptors.
Although the mechanisms that regulate folding and maturation of newly synthesized G protein-coupled receptors are crucial for their function, they remain poorly characterized. By yeast two-hybrid screening, we have isolated ANKRD13C, a protein of unknown function, as an interacting partner for the DP receptor for prostaglandin D(2). In the present study we report the characterization of this novel protein as a regulator of DP biogenesis and trafficking in the biosynthetic pathway. Co-localization by confocal microscopy with an endoplasmic reticulum (ER) marker, subcellular fractionation experiments, and demonstration of the interaction between ANKRD13C and the cytoplasmic C terminus of DP suggest that ANKRD13C is a protein associated with the cytosolic side of ER membranes. Co-expression of ANKRD13C with DP initially increased receptor protein levels, whereas siRNA-mediated knockdown of endogenous ANKRD13C decreased them. Pulse-chase experiments indicated that ANKRD13C can promote the biogenesis of DP by inhibiting the degradation of newly synthesized receptors. However, a prolonged interaction between ANKRD13C and DP resulted in ER retention of misfolded/unassembled forms of the receptor and to their proteasome-mediated degradation. ANKRD13C also regulated the expression of other GPCRs tested (CRTH2, thromboxane A(2) (TPα), and β2-adrenergic receptor), whereas it did not affect the expression of green fluorescent protein, GRK2 (G protein-coupled receptor kinase 2), and VSVG (vesicular stomatitis virus glycoprotein), showing specificity toward G protein-coupled receptors. Altogether, these results suggest that ANKRD13C acts as a molecular chaperone for G protein-coupled receptors, regulating their biogenesis and exit from the ER.
Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Centre de Recherche Clinique Etienne-Lebel and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada.
Audrey
A
Parent
Sébastien J
SJ
Roy
Christian
C
Iorio-Morin
Marie-Claude
MC
Lépine
Pascale
P
Labrecque
Maxime A
MA
Gallant
Deborah
D
Slipetz
Jean-Luc
JL
Parent
D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis* / Q000235:genetics
C555243:ANKRD13C protein, human; D008565:Membrane Proteins; D018832:Molecular Chaperones; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled