The constitutively active orphan G-protein-coupled receptor GPR39 protects from cell death by increasing secretion of pigment epithelium-derived growth factor.
GPR39 is a constitutively active orphan G-protein-coupled receptor capable of increasing serum response element-mediated transcription. We found GPR39 to be up-regulated in a hippocampal cell line resistant against diverse stimulators of cell death and show that its overexpression protects against oxidative and endoplasmic reticulum stress, as well as against direct activation of the caspase cascade by Bax overexpression. In contrast, silencing GPR39 rendered cells more susceptible to cell death. An array analysis of transcripts induced by GPR39 revealed up-regulation of RGS16 (inhibitor of G-protein signaling 16), which suggested coupling to Galpha(13) and induction of serum response element-mediated transcription by the small GTPase RhoA. In line with this, co-expression of GPR39 with RGS16, dominant-negative RhoA, or serum response factor abolished cell protection, whereas overexpression of the serum response factor protected from cell death. Further downstream the signaling cascade, GPR39 overexpression leads to increased secretion of the cytoprotective pigment epithelium-derived growth factor (PEDF). Medium conditioned by cells overexpressing GPR39 contained 4-fold more PEDF, and when stripped off it lost most but not all of its protective properties. We conclude that GPR39 is a novel inhibitor of cell death, which might represent a therapeutic target with implications for processes involving apoptosis and endoplasmic reticulum stress like cancer, ischemia/reperfusion injury, and neurodegenerative disease.
Dittmer
Sonja
S
Research Group Protective Signaling, Department of Neurology, Heinrich Heine Universität Düsseldorf, Moorenstrasse 5, 40225 Düsseldorf, Germany.
Sahin
Mert
M
Pantlen
Anna
A
Saxena
Ambrish
A
Toutzaris
Diamandis
D
Pina
Ana-Luisa
AL
Geerts
Andreas
A
Golz
Stefan
S
Methner
Axel
A
D000818:Animals; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005136:Eye Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D051379:Mice; D008954:Models, Biological; D009414:Nerve Growth Factors / Q000378:metabolism*; D020710:RGS Proteins / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015843:Serpins / Q000378:metabolism*; D014415:Tunicamycin / Q000494:pharmacology; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D000099174:Pigment Epithelium-Derived Factor
D017077:Culture Media, Conditioned; D005136:Eye Proteins; D009414:Nerve Growth Factors; D020710:RGS Proteins; D043562:Receptors, G-Protein-Coupled; D015843:Serpins; D014415:Tunicamycin; D051028:bcl-2-Associated X Protein; D020742:rhoA GTP-Binding Protein; D000099174:Pigment Epithelium-Derived Factor; C495797:GPR39 protein, human; C512928:GPR39 protein, mouse; C107413:RGS16 protein