Production of homocysteine in serum-starved apoptotic PC12 cells depends on the activation and modification of Ras

• Published in: Neuroscience letters 2005-12, Vol.391 (1), p.56-61
• Main Authors: Barbakadze, T., Zhuravliova, E., Sepashvili, M., Zaalishvili, E., Ramsden, J.J., Bátor, J., Szeberényi, J., Mikeladze, D.
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis - physiology; Biological and medical sciences; Culture Media, Serum-Free; Farnesylation; Fundamental and applied biological sciences. Psychology; Homocysteine; Homocysteine - biosynthesis; Humans; NF-kappa B - metabolism; Nitrosylation; PC12 Cells; Protein Prenylation - physiology; Proto-Oncogene Proteins c-fos - metabolism; Ras; ras Proteins - genetics; ras Proteins - metabolism; Rats; Signal Transduction - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2005.08.039

PC12 pheochromocytoma cells expressing a dominant inhibitory mutant of Ha-Ras (M-M17-26) and PC12 cells transfected with normal c-RasH (M-CR3B) have been used to investigate the role of nitrosylation and farnesylation of Ras on the production of homocysteine and the activities of the redox-sensitive transcription factors NF-κB and c-Fos. We found that under serum and nerve growth factor withdrawal conditions undifferentiated apoptotic M-CR3B cells accumulated more homocysteine than M-M17-26 cells, and the production of homocysteine decreased in the presence of manumycin and increased in the presence of l-NAME. Furthermore, we have shown that manumycin increased the activity of c-Fos in the M-CR3B cells and decreased the activity of NF-κB, while l-NAME decreased the activities of both transcription factors, and accelerated apoptosis of M-CR3B cells. In contrast, in M-M17-26 cells manumycin did not change the activity of c-Fos, nor the activity of NF-κB. We conclude that trophic factor withdrawal stimulates Ras, which apparently through the Rac/NADPH oxidase system induces permanent oxidative stress, modulates the activities of NF-κB and c-Fos, induces production of homocysteine and accelerates apoptosis. Nitrosylation of Ras is necessary for maintaining the survival of PC12 cells, while farnesylation of Ras stimulates apoptosis under withdrawal conditions.