The labile nature of the insulin signal(s) for the stimulation of DNA synthesis in mouse lens epithelial and 3T3 cells | JoVE VisualizeThe labile nature of the insulin signal(s) for the stimulation of DNA synthesis in mouse lens epithelial and 3T3 cells
View abstract on PubMed
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- Insulin is a key hormone regulating cellular metabolism and growth.
- The intracellular signaling pathways initiated by insulin binding are complex.
- Understanding insulin's role in DNA synthesis is crucial for cell cycle regulation.
Purpose of the Study:
- To investigate the stability and duration of intracellular signals generated by insulin.
- To determine the kinetic requirements for insulin-induced DNA synthesis.
- To elucidate the nature of the insulin-mediated signal for cell proliferation.
Main Methods:
- Kinetic analysis of DNA synthesis in cultured murine lens epithelial and Swiss 3T3 cells.
- Experimental manipulation of insulin concentration and removal over time.
- Measurement of the lag phase before DNA synthesis initiation after insulin stimulation and removal.
Main Results:
- Insulin stimulation of DNA synthesis exhibited a 14.5-hour lag phase.
- Complete removal of insulin led to a rapid loss of the intracellular signal (half-time of 2 minutes).
- Partial removal (dilution) resulted in a slower signal decay (half-time of 18.4 minutes), requiring a full lag phase upon re-addition.
Conclusions:
- Insulin-induced intracellular signals for DNA synthesis are highly transient.
- Continuous insulin receptor binding is necessary to maintain the signal for cell cycle progression to S phase.
- Sodium vanadate stabilizes the insulin signal, suggesting the tyrosine-phosphorylated insulin receptor or its product is the signaling molecule.
