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The antiapoptotic effect of guanosine is mediated by the activation of the PI 3-kinase/AKT/PKB pathway in cultured rat astrocytes
- Publication Year :
- 2004
-
Abstract
- Guanosine has many trophic effects in the CNS, including the stimulation of neurotrophic factor synthesis and release by astrocytes, which protect neurons against excitotoxic death. Therefore, we questioned whether guanosine protected astrocytes against apoptosis induced by staurosporine. We evaluated apoptosis in cultured rat brain astrocytes, following exposure (3 h) to 100 nM staurosporine by acridine orange staining or by oligonucleosome, or caspase-3 ELISA assays. Staurosporine promoted apoptosis rapidly, reaching its maximal effect (approximately 10-fold over basal apoptotic values) in 18-24 h after its administration to astrocytes. Guanosine, added to the culture medium for 4 h, starting from 1 h prior to staurosporine, reduced the proportion of apoptotic cells in a concentration-dependent manner. The IC50 value for the inhibitory effect of guanosine is 7.5 x 10(-5) M. The protective effect of guanosine was not affected by inhibiting the nucleoside transporters by propentophylline, or by the selective antagonists of the adenosine A1 or A2 receptors (DPCPX or DMPX), or by an antagonist of the P2X and P2Y purine receptors (suramin). In contrast, pretreatment of astrocytes with pertussis toxin, which uncouples Gi-proteins from their receptors, abolished the antiapoptotic effect of guanosine. The protective effect of guanosine was also reduced by pretreatment of astrocytes with inhibitors of the phosphoinositide 3-kinase (PI3K; LY294002, 30 microM) or the MAPK pathway (PD98059, 10 microM). Addition of guanosine caused a rapid phosphorylation of Akt/PKB, and glycogen synthase kinase-3beta (GSK-3beta) and induced an upregulation of Bcl-2 mRNA and protein expression. These data demonstrate that guanosine protects astrocytes against staurosporine-induced apoptosis by activating multiple pathways, and these are mediated by a Gi-protein-coupled putative guanosine receptor.
- Subjects :
- Purinergic Antagonists
MAP Kinase Signaling System
Guanosine
Apoptosis
Protein Serine-Threonine Kinases
Biology
Glycogen Synthase Kinase 3
Phosphatidylinositol 3-Kinases
Cellular and Molecular Neuroscience
chemistry.chemical_compound
Proto-Oncogene Proteins
medicine
Animals
Staurosporine
RNA, Messenger
Enzyme Inhibitors
Phosphorylation
Protein kinase B
Cells, Cultured
PI3K/AKT/mTOR pathway
Glycogen Synthase Kinase 3 beta
Caspase 3
Receptors, Purinergic
Receptors, Purinergic P1
Molecular biology
Rats
Up-Regulation
medicine.anatomical_structure
Animals, Newborn
Proto-Oncogene Proteins c-bcl-2
Purinergic P1 Receptor Antagonists
Neurology
chemistry
Astrocytes
Caspases
DMPX
Neuroglia
Proto-Oncogene Proteins c-akt
Nucleoside
medicine.drug
Astrocyte
Subjects
Details
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....7b9b10a8dc2281ee453f7db8831fe150