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The ras suppressor, RSU-1, enhances nerve growth factor-induced differentiation of PC12 cells and induces p21CIP
L Masuelli1, S Ettenberg, F Vasaturo
1Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
Abstract:
The Rsu-1 Ras suppressor gene was isolated based on its ability to inhibit v-Ras transformation. Using Rsu-1 transfectants of the pheochromocytoma cell line PC12, we demonstrated previously that Rsu-1 expression inhibited Jun kinase activation but enhanced Erk2 activation in response to epidermal growth factor. In the present study, the Rsu-1 PC12 transfectants were used to investigate the role of Rsu-1 in nerve growth factor (NGF)- and v-Ki-ras-mediated neuronal differentiation. NGF-induced neurite extension was enhanced, not inhibited, by the expression of Rsu-1 in PC12 cells. The activation of Erk kinase activity in response to NGF was sustained longer in the Rsu-1 transfectants compared with the vector control cells. During NGF-mediated differentiation, an increase in the expression of specific mRNAs for the early response genes Fos, cJun, and NGF1a was detected in both the vector control and Rsu-1 transfectants. The expression of the differentiation-specific genes VGF8 and SCG10 was similar in Rsu-1 transfectants compared with the vector control cells. The induction of Rsu-1 expression in these cell lines did not inhibit v-Ki-ras-induced differentiation, as measured by neurite extension. These data suggest that although Rsu-1 blocked some Ras-dependent response(s), these responses were not required for differentiation. Moreover, the induction of Rsu-1 expression in the PC12 clones resulted in growth inhibition and p21(WAF/CIP) expression. Hence, Rsu-1 expression enhances NGF-induced differentiation while inhibiting the growth of cells.
Insights
Ras suppressor-1 (Rsu-1) enhances nerve growth factor (NGF)-induced neuronal differentiation in PC12 cells. Rsu-1 also inhibits cell growth and p21(WAF/CIP) expression, suggesting distinct roles in differentiation and proliferation.
Area of Science:
- Molecular Biology
- Cell Biology
- Neuroscience
Background:
- Ras suppressor-1 (Rsu-1) gene inhibits v-Ras transformation.
- Rsu-1 impacts Jun kinase and Erk2 activation by epidermal growth factor in PC12 cells.
Purpose of the Study:
- Investigate Rsu-1's role in nerve growth factor (NGF)- and v-Ki-ras-mediated neuronal differentiation.
- Determine if Rsu-1 affects Ras-dependent signaling pathways crucial for differentiation.
Main Methods:
- Utilized Rsu-1 transfectants of the PC12 pheochromocytoma cell line.
- Analyzed neurite extension, Erk kinase activity, and gene expression (Fos, cJun, NGF1a, VGF8, SCG10) in response to NGF and v-Ki-ras.
- Assessed growth inhibition and p21(WAF/CIP) expression.
Main Results:
- Rsu-1 expression enhanced NGF-induced neurite extension and sustained Erk kinase activation.
- Rsu-1 did not inhibit v-Ki-ras-induced differentiation.
- Rsu-1 expression led to growth inhibition and increased p21(WAF/CIP) expression.
Conclusions:
- Rsu-1 enhances NGF-mediated neuronal differentiation independently of certain Ras-dependent pathways.
- Rsu-1 plays a dual role, promoting differentiation while inhibiting cell growth.