title: Inhibition of neuronal cell death after retinoic acid-induced down-regulation of P2X7 nucleotide receptor expression.
abstract: Apoptosis is a major mechanism for cell death in the nervous system during development. P2X(7) nucleotide receptors are ionotropic ATP receptors that mediate cell death under pathological conditions. We developed an in vitro protocol to investigate the expression and functional responses of P2X(7) nucleotide receptors during retinoic acid (RA)-induced neuronal differentiation of human SH-SY5Y neuroblastoma cells. Neuronal differentiation was examined measuring cellular growth arrest and neuritic processes elongation. We found that SH-SY5Y cells treated for 5 days with RA under low serum content exhibited a neuron-like phenotype with neurites extending more than twice the length of the cell body and cell growth arrest. Concurrently, we detected the abolishment of intracellular-free calcium mobilization and the down-regulation of P2X(7) nucleotide receptor protein expression that protected differentiated cells from neuronal cell death and reduced caspase-3 cleavage-induced by P2X(7) nucleotide receptor agonist. The role of P2X(7) nucleotide receptors in neuronal death was established by selectively antagonizing the receptor with KN-62 prior to its activation. We assessed the involvement of protein kinases and found that p38 signaling was activated in undifferentiated after nucleotide stimulation, but abolished by the differentiating RA pretreatment. Importantly, P2X(7) receptor-induced caspase-3 cleavage was blocked by the p38 protein kinase specific inhibitor PD169316. Taken together, our results suggest that RA treatment of human SH-SY5Y cells leads to decreased P2X(7) nucleotide receptor protein expression thus protecting differentiated cells from extracellular nucleotide-induced neuronal death, and p38 signaling pathway is critically involved in this protection of RA-differentiated cells.
authors.affiliation: Department of Biology, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA.
authors.forename: Elsie A
authors.initials: EA
authors.lastname: Orellano
authors.forename: Omayra J
authors.initials: OJ
authors.lastname: Rivera
authors.forename: Migdalia
authors.initials: M
authors.lastname: Chevres
authors.forename: Nataliya E
authors.initials: NE
authors.lastname: Chorna
authors.forename: Fernando A
authors.initials: FA
authors.lastname: González
mesh_terms: D001932:Brain Neoplasms / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D020013:Calcium Signaling / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology; D009447:Neuroblastoma / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D018048:Receptors, Purinergic P2 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D058486:Receptors, Purinergic P2X7; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology
chemical_list: C546468:P2RX7 protein, human; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D014212:Tretinoin; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3