[Effect of synthetic proteasomal inhibitor MG132 on dynamics of EGF-receptor complexes endocytosis in A431 cells].
The effect of proteasomal activity suppression induced by MG132, a synthetic proteasomal inhibitor of EGF-receptor complexes endocytosis in human epidermoid carcinoma A431 cell line, was studied. Using subcellular fractionation in 17% Percoll gradient, it was demonstrated that the addition of MG132 to the cells 15 min following stimulation of EGF endocytosis resulted in a slight accumulation of 125I-EGF in early endosomes, and in much more significant accumulation of the labeled growth factor in late endosomes/lysosomes, as compared to untreated cells. The release of 125I-EGF degradation products into the incubation medium was significantly (3-12-fold) inhibited in the presence of MG132. At the same time biochemical analysis has demonstrated that the EGF receptor itself is not a direct target of proteasomes, since it is revealed as a full-length protein with native mol. mass (170 kDa) in fractions of early and late endosomes and lysosomes. Possible mechanisms of the MG132 effect on intracellular processing of EGF-receptor complexes are discussed.
M S
MS
Melikova
A A
AA
Aksenov
N N
NN
Nikol'skiĭ
E S
ES
Kornilova
D002458:Cell Fractionation; D045744:Cell Line, Tumor; D004705:Endocytosis / Q000187:drug effects; D004815:Epidermal Growth Factor; D066246:ErbB Receptors / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007457:Iodine Radioisotopes; D007976:Leupeptins / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors
D007457:Iodine Radioisotopes; D007976:Leupeptins; D061988:Proteasome Inhibitors; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde