Journal Club – 22.07.15

GPR15L is an epithelial inflammation-derived pruritogen

Pang-Yen Tseng and Mark A. Hoon*

Molecular Genetics Section, National Institute of Dental and Craniofacial Research/ NIH, 35 Convent Drive, Bethesda, MD 20892, USA.
*Corresponding author. Email: mark.hoon@nih.gov

Itch is an unpleasant sensation that often accompanies chronic dermatological conditions. Although many of the itch receptors and the neural pathways underlying this sensation are known, the identity of endogenous ligands is still not fully appreciated. Using an unbiased bioinformatic approach, we identified GPR15L as a candidate pruritogen whose expression is robustly up-regulated in psoriasis and atopic dermatitis. Although GPR15L was previously shown to be a cognate ligand of the receptor GPR15, expressed in dermal T cells, here we show that it also contributes to pruritogenesis by activating Mas-related G protein–coupled receptors (MRGPRs). GPR15L can selectively stimulate mouse dorsal root ganglion neurons that express Mrgpra3 and evokes intense itch re- sponses. GPR15L causes mast cell degranulation through stimulation of MRGPRX2 and Mrgprb2. Genetic dis- ruption of GPR15L expression attenuates scratch responses in a mouse model of psoriasis. Our study reveals unrecognized features of GRP15L, showing that it is a potent itch-inducing agent.