[The role of Src-kinase in the regulation of endocytosis of EGF-receptor complexes. I. Dynamics of EGF internalization, recycling, sorting, and degradation during inhibition of Src-kinase activity].
In the present work, the role of Src-kinase in regulation of different stages of EGF-receptor endocytosis was studied. We used murine fibroblasts with knockout of Src gene and CGP77675, and the inhibitor of Src-family kinases. The absence of Src protein in the cells did not lead to any changes in the rates of 125I-EGF internalization or recycling and caused only slight decrease in the rate of its degradation. At the same time, treatment of the wild type cells with the inhibitor resulted in a small decrease in internalization rate and an increase in recycling. The influence of the inhibitor on 125I-EGF degradation was also more pronounced. But even in this case, the effects were no more than 30% of control values. CGP77675 extended the same effect upon cells of HER14 and HC11 lines. Subcellular fractionation of these cells in Percoll gradient has also demonstrated a slight inhibition of 125I-EGF sorting from early to late endosomes. The more pronounced effect of the Src-family kinase inhibitor on the EGF endocytosis, compared to that of the absence of a single Src protein, suggests a compensating mechanism of the Src-family kinases. A conclusion is made that in spite of a slight influence on practically all stages of intracellular pathway of EGF-receptor complexes, Src-kinases are obviously not the key regulators of their endocytosis.
Zheleznova
N N
NN
Institute of Cytology RAS, St. Petersburg. zheleznova@hotmail.com
Melikova
M S
MS
Nikol'skiĭ
N N
NN
Kornilova
E S
ES
D000818:Animals; D002460:Cell Line; D004705:Endocytosis / Q000187:drug effects*; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D005347:Fibroblasts; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D011743:Pyrimidines / Q000494:pharmacology*; D011758:Pyrroles / Q000494:pharmacology*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics
D011743:Pyrimidines; D011758:Pyrroles; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D019061:src-Family Kinases; C119957:CGP 77675