ABSTRACT
BACKGROUND: Both epidermal growth factor (EGF) and insulin transfer their signals into cells by two primary signal transduction pathways,including phosphatidylinositol 3-kinase (PI3K) pathway and mitogen activated protein kinases (MAPK) pathway.But they have different physiological functions.OBJECTIVE: To comparatively assay the dynamic behaviors of phosphoproteomes between EGF and insulin signal transductions in mouse hepatocytes and find key signal proteins.DESIGN,TIME AND SETTING: Randomized grouping controlled observation experiment was performed in the laboratory of Molecular Biology,Luzhou Medical College between July 2005 and April 2006.MATERIALS: Hepatocytes were from Kunming mice of closed population.METHODS: The primarily cultured mouse hepatocytes were labeled with 32p isotope and then randomly divided into three groups: control,EGF-stimulated (received 10 μg/L EGF),and insulin-stimulated (received 100 nmol/L insulin) groups.MAIN OUTCOME MEASURES: After mouse hepatocytes were treated with EGF and insulin for 0,5,20,60 and 120 minutes,the dynamic behaviors of phosphoproteomes(I.e,phosphorylated level) between EGF and insulin signal transductions were comparatively analyzed by two-dimensional electrophoresis method.RESULTS: The categories of all phosphorylated proteins between EGF and insulin-stimulated phosphoproteomes had no apparent difference.The dynamic behaviors of phosphoproteomes of most proteins during EGF signal transduction are parallel with those during insulin stimulation,except the dynamic behaviors of 4 proteins are different significantly.CONCLUSION: Aforementioned 4 phosphorylated proteins were most probably the key members that could distinguish between two signal transduction pathways ornetworks,and determined their major physiological functions respectively.
ABSTRACT
Objective:To discuss a simple method for flow cytometric analysis of cell DNA stained with DAPI and Hoechst33342.Methods:HT 29 cells stained with DAPI,Hoechst33342 or PI were measured by BD FACSAria and the percentages of cells in G0/G1,S and G2/M phases with three staining me-thods,then the results were analyzed and compared.Before measurement we monitored the quality of DNA analysis of flow cytometer through UV beads QC experiment and analyzed the standard chicken erythrocyte nuclei(CEN) and calf thymocyte nuclei(CTN) stained with DAPI and Hoechst33342.Results:CV value of UV peak was 2.4 after QC experiments.There were 4 peaks on CEN histograms and the ratios of peak channel mean of G2/G1,G3/G1,and G4/G1 were about 2,3,and 4 respectively.Both CV values of the first peak were 2.4.There were 2 peaks on CTN histograms and the ratio of peak channel mean of G2/G1 was 1.97,and CV value of G0/G1 2.4.The complete cell cycle of HT29 cells stained with DAPI,Hoechst33342 or PI was showed entirely,CV values were 3.40,3.02 and 4.42,respectively,and the percentages of cells in G0/G1 were 60.86%,60.22% and 60.81%,respectively,in S,28.85%,29.70% and 29.82%,respectively,and in G2/M,10.29%,9.09% and 9.37%,respectively.The results by the three methods showed no difference.Conclusion:This method for measurement of cellular DNA content is a simple and efficient approach to determining cell cycle and can be the first choice when using flow cytometer with 355 nm UV.