title: Phenotypic changes, signaling pathway, and functional correlates of GPR17-expressing neural precursor cells during oligodendrocyte differentiation.
abstract: The developing and mature central nervous system contains neural precursor cells expressing the proteoglycan NG2. Some of these cells continuously differentiate to myelin-forming oligodendrocytes; knowledge of the destiny of NG2(+) precursors would benefit from the characterization of new key functional players. In this respect, the G protein-coupled membrane receptor GPR17 has recently emerged as a new timer of oligodendrogliogenesis. Here, we used purified oligodendrocyte precursor cells (OPCs) to fully define the immunophenotype of the GPR17-expressing cells during OPC differentiation, unveil its native signaling pathway, and assess the functional consequences of GPR17 activation by its putative endogenous ligands, uracil nucleotides and cysteinyl leukotrienes (cysLTs). GPR17 presence was restricted to very early differentiation stages and completely segregated from that of mature myelin. Specifically, GPR17 decorated two subsets of slowly proliferating NG2(+) OPCs: (i) morphologically immature cells expressing other early proteins like Olig2 and PDGF receptor-α, and (ii) ramified preoligodendrocytes already expressing more mature factors, like O4 and O1. Thus, GPR17 is a new marker of these transition stages. In OPCs, GPR17 activation by either uracil nucleotides or cysLTs resulted in potent inhibition of intracellular cAMP formation. This effect was counteracted by GPR17 antagonists and receptor silencing with siRNAs. Finally, uracil nucleotides promoted and GPR17 inhibition, by either antagonists or siRNAs, impaired the normal program of OPC differentiation. These data have implications for the in vivo behavior of NG2(+) OPCs and point to uracil nucleotides and cysLTs as main extrinsic local regulators of these cells under physiological conditions and during myelin repair.
authors.affiliation: Laboratory of Molecular and Cellular Pharmacology of Purinergic Transmission, Department of Pharmacological Sciences, University of Milan, 20133 Milan, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Fumagalli
authors.forename: Simona
authors.initials: S
authors.lastname: Daniele
authors.forename: Davide
authors.initials: D
authors.lastname: Lecca
authors.forename: Philip R
authors.initials: PR
authors.lastname: Lee
authors.forename: Chiara
authors.initials: C
authors.lastname: Parravicini
authors.forename: R Douglas
authors.initials: RD
authors.lastname: Fields
authors.forename: Patrizia
authors.initials: P
authors.lastname: Rosa
authors.forename: Flavia
authors.initials: F
authors.lastname: Antonucci
authors.forename: Claudia
authors.initials: C
authors.lastname: Verderio
authors.forename: M Letizia
authors.initials: ML
authors.lastname: Trincavelli
authors.forename: Placido
authors.initials: P
authors.lastname: Bramanti
authors.forename: Claudia
authors.initials: C
authors.lastname: Martini
authors.forename: Maria P
authors.initials: MP
authors.lastname: Abbracchio
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D020868:Gene Silencing; D009186:Myelin Sheath / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D000076104:Oligodendrocyte Transcription Factor 2; D009836:Oligodendroglia / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D017479:Receptors, Platelet-Derived Growth Factor / Q000096:biosynthesis; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D014500:Uracil Nucleotides / Q000378:metabolism / Q000494:pharmacology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009419:Nerve Tissue Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D043562:Receptors, G-Protein-Coupled; D017479:Receptors, Platelet-Derived Growth Factor; D014500:Uracil Nucleotides; C514731:GPR17 protein, rat; C522729:Olig2 protein, rat