윤정빈
심우영 허충림 김성수 대피지 1999;37;12
1760-1768
Background : Insulin exerts an effect on cell proliferation
and inhibition of apoptosis. However, the actions
of insulin on cell cycle progression and signal
transduction pathway are not well understood and
insulin shows diverse effects on cell proliferation
depending on cell types. Objective : We attempted
to understand the underlying mechanism by which
insulin exerts this proliferative effect on 3T3
L1 fibroblasts by various markers of cell proliferation.
Method : We investigated the effect of insulin on
cell proliferation by [3H]thymidine incorporation,
analyzing the cell cycle stages by flow cytometric
measurement of DNA content per cell, cell counting,
analysing cell division as well as the signal transduction
pathway of insulin by measuring of phosphatidylinositol
3-kinase(PI3-kinase) and p44/42 mitogen-activated
protein kinase (p44/42 MAPK/ERK) activity. Results
: The results were as follows : 1. Total accumulated
[3H]thymidine incorporation increased approximately
two-fold with insulin over the 0.5% serum control
at 48 h incubation, and the maximal rate of DNA
synthesis was observed during 8-12 h incubation
and continuously declined until 48 h without a second
increase in DNA synthnesis. 2. The flow cytometric
analysis of cell population distribution showed
that insulin increased the cell population in S
phase. 3. After insulin treatment for 48 h, cell
number was increased approximately 45% in comparison
with 0.5% serum control. 4. The cell division analysed
after staining 3T3 L1 fibroblasts with carboxyfluorescein
diacetate succinimidyl ester (CFSE). Cell division
occured only once in 24h after insulin treatment.
5. Insulin stimulated PI3-kinase and p44/42 MAPK/ERK
activity about three and two-folds, respectively.
Conclusion : Taken together, this data indicates
that insulin stimulated the transit from G0/G1 to
S phase, progressed cell cycle through G2/M phase,
increased the cell number and PI3-kinase, p44/42
MAPK/ERK stimulate cell proliferation. However,
under our experimental conditions, i |
