TY - JOUR
T1 - Enhanced expression of Harvey ras induced by serum deprivation in cultured astrocytes
AU - Messina, Samantha
AU - Molinaro, Gemma
AU - Bruno, Valeria
AU - Battaglia, Giuseppe
AU - Spinsanti, Paola
AU - Pardo, Alba Di
AU - Nicoletti, Ferdinando
AU - Frati, Luigi
AU - Porcellini, Antonio
PY - 2008/7
Y1 - 2008/7
N2 - Trophic deprivation contributes to astrocyte damage that occurs in acute and chronic neurodegenerative disorders. Unraveling the underlying mechanisms may pave way to novel cytoprotective strategies. Cultured mouse astrocytes responded to trophic deprivation with a large and transient increase in the expression of p21ras, which was secondary to an enhanced formation of reactive oxygen species (ROS) detected by cytofluorimetric analysis after preloading with 2′,7′-dichlorofluorescein diacetate. The increase in p21ras levels was largely attenuated by the reducing agent, N-ace- tylcysteine, which was proven to reduce ROS formation in astrocytes subjected to serum deprivation. We extended the analysis to the Ha-Ras isoform, which has been implicated in mechanisms of cytotoxicity. We found that serum deprivation enhanced the expression and activity of Ha-Ras without changing Ha-Ras mRNA levels. The increase in Ha-Ras levels was sensitive to the protein synthesis inhibitor, cyclohex-imide, suggesting that serum deprivation increases translation of preformed Ha-Ras mRNA. The late decline in Ha-Ras levels observed after 60 min was prevented by the protea- some inhibitor, MG132, as well as by the selective mitogen- activated protein kinase (MAPK) inhibitor, PD98059. Serum deprivation led to the activation of the MAPK pathway in cultured astrocytes, as shown by an increase in phosphorylated extracellular signal-regulated kinase 1/2 levels after 5 and 30 min. Finally, using the siRNA technology, we found that an acute knock-down of Ha-Ras was protective against astrocyte damage induced by serum deprivation. We conclude that cultured astrocytes respond to trophic deprivation with an increased expression in Ha-Ras, which is limited by the concomitant activation of the MAPK pathway, but is nevertheless involved in the pathophysiology of cell damage.
AB - Trophic deprivation contributes to astrocyte damage that occurs in acute and chronic neurodegenerative disorders. Unraveling the underlying mechanisms may pave way to novel cytoprotective strategies. Cultured mouse astrocytes responded to trophic deprivation with a large and transient increase in the expression of p21ras, which was secondary to an enhanced formation of reactive oxygen species (ROS) detected by cytofluorimetric analysis after preloading with 2′,7′-dichlorofluorescein diacetate. The increase in p21ras levels was largely attenuated by the reducing agent, N-ace- tylcysteine, which was proven to reduce ROS formation in astrocytes subjected to serum deprivation. We extended the analysis to the Ha-Ras isoform, which has been implicated in mechanisms of cytotoxicity. We found that serum deprivation enhanced the expression and activity of Ha-Ras without changing Ha-Ras mRNA levels. The increase in Ha-Ras levels was sensitive to the protein synthesis inhibitor, cyclohex-imide, suggesting that serum deprivation increases translation of preformed Ha-Ras mRNA. The late decline in Ha-Ras levels observed after 60 min was prevented by the protea- some inhibitor, MG132, as well as by the selective mitogen- activated protein kinase (MAPK) inhibitor, PD98059. Serum deprivation led to the activation of the MAPK pathway in cultured astrocytes, as shown by an increase in phosphorylated extracellular signal-regulated kinase 1/2 levels after 5 and 30 min. Finally, using the siRNA technology, we found that an acute knock-down of Ha-Ras was protective against astrocyte damage induced by serum deprivation. We conclude that cultured astrocytes respond to trophic deprivation with an increased expression in Ha-Ras, which is limited by the concomitant activation of the MAPK pathway, but is nevertheless involved in the pathophysiology of cell damage.
KW - Cultured astrocytes
KW - Mitogen-activated protein kinase pathway
KW - Ras protein
KW - Trophic deprivation
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U2 - 10.1111/j.1471-4159.2008.05420.x
DO - 10.1111/j.1471-4159.2008.05420.x
M3 - Article
C2 - 18410509
AN - SCOPUS:51649124340
SN - 0022-3042
VL - 106
SP - 551
EP - 559
JO - Journal of Neurochemistry
JF - Journal of Neurochemistry
IS - 2
ER -