EFFECT OF EGF ON UBIQUITINILATION AND PROTEASOME-DEPENDENT DEGRADATION OF PHOSPHOLIPASE
Cy1 IN A431 CELLS
A. L. Evdonin, N. V. Tsupkina, N. N. Nikolsky, N. D. Medvedeva 1
Institute of Cytology RAS, St. Petersburg, Russia;
1 e-mail: evdonin@mail.ru
Phospholipase Cy1 (PLC γ1), an enzyme participating in phosphoinositide turnover, is one of the key elements in
cell signaling. Here it is shown that treatment of A431 carcinoma cells with proteasome inhibitors Mgl32 and lactacystin results in
increasing the PLC γ1 intracellular level. Simultaneously, several additional bands with lower electrophoretic mobilities were
detected on immunoblots, using anti-PLC γ1 antibodies. PLC γ1 ubiquitinilation was shown using immunoprecepitation.
In control A431 cells, PLC γ1 is ubiquitinilated, but the addition of EOF greatly induces the ubiquitinilation of the protein. Assiciation
of PLC γ1 with ubiquitin-ligase c-Cb1 was shown. Dynamics of ubiquitinilation under EGF treatment is in a close agreement with
that of association of PLC γ1 and c-Cb1. It is concluded that PLC γ1 is ubiquitinilated and degraded by proteasomes.
PLC γ1 ubiquitinilation is an EGF-dependent process Phospholipase Cy1 (PLC γ1), an enzyme participating in
phosphoinositide turnover, is one of the key elements in cell signaling. Here it is shown that treatment of A431 carcinoma cells with
proteasome inhibitors Mg132 and lactacystin results in increasing the PLC γ1 intracellular level. Simultaneously, several additional
bands with lower electrophoretic mobilities were detected on immunoblots, using anti-PLC gl antibodies. PLC γ1 ubiquitinilation
was shown using immunoprecepitation. In control A431 cells, PLC γ1 is ubiquitinilated, but the addition of EOF greatly induces
the ubiquitinilation of the protein. Assiciation of PLC γ1 with ubiquitin-ligase c-Cb1 was shown. Dynamics of ubiquitinilation under
EGF treatment is in a close agreement with that of association of PLC γ1 and c-Cb1. It is concluded that PLC γ1 is
ubiquitinilated and degraded by proteasomes. PLC γ1 ubiquitinilation is an EGF-dependent process.
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