EGFR and Calmodulin Signalling group


Functional Regulation of Rac1 and Cdc42 by Calmodulin

On the basis of the preliminary results obtained recently and on the analysis of the aminoacidic sequence of these GTPases, it seems that CaM interacts with Rac1 and cdc42. Therefore, CaM through these small Rho GTPases could regulate cytoskeleton related cellular processes like cellular mobility and/or endocytic compartment functionality.

Role of PKCδ in the degradation of EGFR and LDL. Relevance in different types of tumors

The PKCδ activity is necessary for the efficient degradation of the EGF-EGFR complex. The degradation of the EGF-EGFR depends on its own signaling, its ubiquitinylation and the subsequent traffic of the receptor to the multivesicular bodies (MBVs) /lysosomes. The role of PKCδ in the different processes that participate in the degradation of the receptor will be analyzed. In a comparative way, the role of PKCδ in the degradation of LDL will also be studied. LDL is transported to the early endosomes by binding to its specific receptor, but it does not participate in the later transport of LDL to lysosomes. In addition, our interest is focused on the correlation between the levels of PKCδ and EGFR in the putative abnormal traffic of the EGFR in different tumour lines.

Endosomes as signalling platforms

Besides K-Ras, Rac1 and Cdc42 are CaM binding proteins present in the endosomal compartment. Thus, we are analyzing the role of CaM in the EGFR signalling through H-Ras, K-Ras and Rac1 and the dynamics of actin in this location. Since another location and a very important place of action of Rac1, Cdc42, CaM and PKCδ is the plasma membrane, it is also essential to study the cellular processes activated by EGFR in plasma membrane in which proteins take part. Mainly, we will focus our investigations in endocytosis, mobility, formation of lamellipodia and cellular migration.

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