title: Regulation of proteasome activity by P2Y2receptor underlies the neuroprotective effects of extracellular nucleotides.
abstract: The Ubiquitin-Proteasome System (UPS) is essential for the regulation of the cellular proteostasis. Indeed, it has been postulated that an UPS dysregulation is the common mechanism that underlies several neurological disorders. Considering that extracellular nucleotides, through their selective P2Y2receptor (P2Y2R), play a neuroprotective role in various neurological disorders that course with an UPS impairment, we wonder if this neuroprotective capacity resulted from their ability to modulate the UPS. Using a cellular model expressing two different UPS reporters, we found that the stimulation of P2Y2R by its selective agonist Up4U induced a significant reduction of UPS reporter levels. This reduction was due to an increase in two of the three peptidase proteasome activities, chymotrypsin and postglutamyl, caused by an increased expression of proteasome constitutive catalytic subunits β1 and β5. The intracellular signaling pathway involved required the activation of IP3/MEK1/2/ERK but was independent of PKC or PKA. Interestingly, the P2Y2R activation was able to revert both UPS-reporter accumulation and the cell death induced by a prolonged inhibition of UPS. Finally, we also observed that intracerebroventricular administration of Up4U induced a significant increase both of chymotrypsin and postglutamyl activities as well as an increased expression of proteasome subunits β1 and β5 in the hippocampus of wild-type mice, but not in P2Y2R KO mice. All these results strongly suggest that the capacity to modulate the UPS activity via P2Y2R is the molecular mechanism which is how the nucleotides play a neuroprotective role in neurological disorders.
authors: Department of Biochemistry and Molecular Biology, Veterinary School, Complutense University of Madrid, Avda. Puerta de Hierro S/N, 28040 Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.
authors: Laura
authors: L
authors: de Diego-García
authors: Department of Biochemistry and Molecular Biology, Veterinary School, Complutense University of Madrid, Avda. Puerta de Hierro S/N, 28040 Madrid, Spain.
authors: Mercedes
authors: M
authors: Ramírez-Escudero
authors: Department of Biochemistry and Molecular Biology, Veterinary School, Complutense University of Madrid, Avda. Puerta de Hierro S/N, 28040 Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.
authors: Álvaro
authors: Á
authors: Sebastián-Serrano
authors: Department of Biochemistry and Molecular Biology, Veterinary School, Complutense University of Madrid, Avda. Puerta de Hierro S/N, 28040 Madrid, Spain; Centro de Biología Molecular "Severo Ochoa" (CBM"SO"), CSIC/UAM, 28049 Madrid, Spain.
authors: Juan Ignacio
authors: JI
authors: Diaz-Hernández
authors: Faculty of Optic and Optometry, Complutense University of Madrid, Avda. Puerta de Hierro S/N, 28040 Madrid, Spain.
authors: Jesús
authors: J
authors: Pintor
authors: Centro de Biología Molecular "Severo Ochoa" (CBM"SO"), CSIC/UAM, 28049 Madrid, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Spain.
authors: José J
authors: JJ
authors: Lucas
authors: Department of Biochemistry and Molecular Biology, Veterinary School, Complutense University of Madrid, Avda. Puerta de Hierro S/N, 28040 Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain. Electronic address: migueldiaz@ucm.es.
authors: Miguel
authors: M
authors: Díaz-Hernández
mesh_terms: D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000378:metabolism / Q000494:pharmacology*; D009711:Nucleotides / Q000378:metabolism / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D058912:Purinergic P2Y Receptor Agonists / Q000378:metabolism / Q000494:pharmacology*; D058473:Receptors, Purinergic P2Y2 / Q000378:metabolism*; D014500:Uracil Nucleotides / Q000378:metabolism / Q000494:pharmacology
chemical_list: D018696:Neuroprotective Agents; D009711:Nucleotides; D058912:Purinergic P2Y Receptor Agonists; D058473:Receptors, Purinergic P2Y2; D014500:Uracil Nucleotides; C035436:uridine 5'-tetraphosphate; D015544:Inositol 1,4,5-Trisphosphate; D046988:Proteasome Endopeptidase Complex; C478802:Psmb5 protein, mouse
keywords: Chymotrypsin-like activity; Neurological disorders; P2Y2 receptor; Postglutamyl-like activity; Ubiquitin-proteasome-system; Up4U