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Characterization of activated and normal mouse Mos gene in murine 3T3 cells
R S Paules1, J Resnick, A B Kasenally
1Mammalian Molecular Genetics Group, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Abstract:
We have characterized the mouse Mos proto-oncogene product, pp39Mos, in murine fibroblasts. When expressed in NIH3T3 cells under the influence of the long terminal repeat regulatory element from Moloney murine sarcoma virus [NIH(pTS-1) cells], the Mos protein was present in low levels and had a half-life of about 30 min. In extracts from NIH(pTS-1) cells, we detected additional forms of Mos protein that apparently arose from internal initiation codons (p24Mos and p29Mos) or from upstream non-AUG initiation codons (p42Mos and p44Mos). The Mos protein was found to exist in these cells as a phosphoprotein, pp39Mos, and, when immunoprecipitated with an antiserum specific for the Mos N-terminus [anti-Mos(6-24)], had autophosphorylating kinase activity. We found that anti-Mos(6-24) also detected non-Mos protein kinase activity and non-Mos phosphoproteins in addition to p39Mos. We present evidence, on both the RNA and protein levels, that non-transformed mouse 3T3 cells do not express endogenous Mos.
Insights
Researchers characterized the mouse Mos proto-oncogene product, pp39Mos, in fibroblasts. They found multiple Mos protein forms and identified its autophosphorylating kinase activity in NIH(pTS-1) cells.
Area of Science:
- Molecular Biology
- Oncogenes
- Protein Biochemistry
Background:
- The Mos proto-oncogene plays a critical role in cellular signaling pathways.
- Understanding the expression and activity of Mos protein is crucial for cancer research.
Purpose of the Study:
- To characterize the mouse Mos proto-oncogene product, pp39Mos, in murine fibroblasts.
- To investigate the different forms and kinase activity of Mos protein.
- To determine the endogenous expression of Mos in non-transformed mouse cells.
Main Methods:
- Expression of Mos proto-oncogene in NIH3T3 cells using Moloney murine sarcoma virus regulatory element.
- Analysis of Mos protein levels, half-life, and forms using biochemical techniques.
- Immunoprecipitation with N-terminus specific antiserum to assess kinase activity.
- RNA and protein level analysis to detect endogenous Mos expression.
Main Results:
- Mos protein was expressed at low levels with a half-life of approximately 30 minutes in NIH(pTS-1) cells.
- Multiple Mos protein forms (p24Mos, p29Mos, p42Mos, p44Mos) were detected, arising from alternative initiation codons.
- pp39Mos exhibited autophosphorylating kinase activity.
- The antiserum detected both Mos-specific and non-Mos protein kinase activities.
- Non-transformed mouse 3T3 cells showed no detectable endogenous Mos expression at RNA or protein levels.
Conclusions:
- The mouse Mos proto-oncogene product, pp39Mos, exists in multiple forms in NIH3T3 cells and possesses autophosphorylating kinase activity.
- Alternative initiation codons contribute to the heterogeneity of Mos protein forms.
- Endogenous Mos expression is absent in non-transformed mouse 3T3 cells, suggesting its role is primarily linked to transformation or specific cellular contexts.