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Updated: Aug 19, 2026
Analysis of Cell Cycle Position in Mammalian Cells
Published on: January 21, 2012
Further characterization of the c-mos transcript and its cell cycle specific expression in NIH3T3 cells
C Gao1, R B Arlinghaus, B Singh
1Department of Molecular Pathology, University of Texas MD Anderson Cancer Centre, Houston 77030, USA.
Abstract:
The mouse c-mos proto-oncogene is primarily expressed in germ cells. Our previous studies demonstrated c-mos RNA expression in mouse somatic cells, with the highest level present in the G2 phase of the cell cycle (Tsui et al., 1993). We have identified the transcription start site of this G2 specific c-mos transcript to be located about 1580 bp upstream from the open reading frame based on RT-PCR and RNase protection experiments. Upstream sequences containing this transcription start site directed highest expression of the luciferase reporter gene in M phase of the cell cycle. These results suggest that c-mos transcripts are produced in G2 phase and that c-Mos protein albeit at extremely low levels would accumulate in M phase.
Insights
The c-mos proto-oncogene, typically found in germ cells, also shows G2 phase expression in mouse somatic cells. Its transcription start site was identified, suggesting c-Mos protein accumulation during M phase.
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- Oncogene Research
Background:
- The c-mos proto-oncogene is mainly expressed in germ cells.
- Previous research indicated c-mos RNA expression in mouse somatic cells, peaking in G2 phase.
- The precise regulation of somatic c-mos expression remained unclear.
Purpose of the Study:
- To identify the transcription start site (TSS) of the G2-specific c-mos transcript in mouse somatic cells.
- To investigate the regulatory role of upstream sequences in controlling c-mos expression during the cell cycle.
- To understand the potential accumulation of c-Mos protein in M phase.
Main Methods:
- Reverse Transcription Polymerase Chain Reaction (RT-PCR) to detect and analyze c-mos RNA.
- RNase protection assays to precisely map RNA transcripts and identify the TSS.
- Reporter gene assays (luciferase) to assess the activity of upstream regulatory sequences.
Main Results:
- The TSS for the G2-specific c-mos transcript was mapped approximately 1580 bp upstream of the open reading frame.
- Upstream sequences containing the identified TSS demonstrated the highest reporter gene expression during M phase.
- These findings indicate cell cycle-dependent transcriptional regulation of c-mos.
Conclusions:
- Somatic c-mos transcripts are produced during the G2 phase of the cell cycle.
- The identified upstream regulatory elements drive expression in M phase.
- Low levels of c-Mos protein are likely to accumulate during M phase, despite transcriptional peaking in G2.
