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P2Y 2 nucleotide receptors inhibit trauma‐induced death of astrocytic cells
Author(s) -
Burgos Michelle,
Neary Joseph T.,
González Fernando A.
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2007.04872.x
Subject(s) - p2y receptor , kinase , receptor , dna fragmentation , microbiology and biotechnology , biology , extracellular , programmed cell death , apoptosis , protein kinase b , protein kinase a , signal transduction , biochemistry , purinergic receptor
Nucleotides as well as other neurotransmitters are known to be released to the extracellular space upon injury. To determine whether nucleotides acting on P2Y 2 nucleotide receptors promote protective or degenerative events after trauma in astrocytic cells, a well‐established model of in vitro brain trauma was applied to 1321N1 cells expressing recombinant P2Y 2 nucleotide receptors (P2Y 2 R‐1321N1). Cellular death was examined by measuring DNA fragmentation and caspase activation. Fragmented DNA was observed 48 h post‐injury in 1321N1 cells, while P2Y 2 nucleotide receptor expressing cells did not show DNA fragmentation. A laddering pattern of fragmented DNA following injury was observed upon inhibition of P2Y 2 nucleotide receptors with suramin. Time‐dependent increases of cleaved caspase‐9, a mitochondrial‐associated caspase, correlated with injury‐induced cellular death. A decreased bax / bcl‐2 gene expression ratio was observed in P2Y 2 R‐1321N1 cells after traumatic injury, while untransfected 1321N1 cells showed a significant time‐dependent increase of the bax / bcl‐2 gene expression ratio. Activation of protein kinases was assessed to determine the signaling pathways involved in cell death and survival responses following traumatic injury. In P2Y 2 R‐1321N1 and 1321N1 cells p38 phosphorylation was stimulated in a time‐dependent manner but the phosphatidylinositol 3‐kinase‐dependent activation of extracellular signal‐regulated kinase 1/2 and protein kinase B (PKB)/Akt was only observed in P2Y 2 R‐1321N1 cells after injury. The stress‐activated protein kinase/c‐Jun NH2‐terminal kinase (SAPK/JNK) signaling pathway was not activated by traumatic injury in either astrocytic cell line. Inhibition of p38 kinase signaling pathway by treatment with PD1693, a MKK3/6 inhibitor, abolished the expression of cleaved caspase‐9, the increase in the bax / bcl‐2 gene expression ratio, as well as the fragmentation of DNA that followed injury of 1321N1 cells. Taken together, our results demonstrate a novel role for P2Y 2 nucleotide receptors and extracellular nucleotides in mediating survival responses to glial cells undergoing cellular death induced by trauma.