FEZ1 protein: little organizational structure, activities related to elements of the cytoskeleton and generation of the flower like phenotype

Author(s)

Daniel Carlos Ferreira Lanza

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2009-08-27

Examining board members

Jörg Kobarg; Claudio Chrysostomo Werneck; Marcelo Damario Gomes; Alexander Henning Ulrich; Celso Eduardo Benedetti

• Advisor: Jörg Kobarg

Abstract

FEZ1 was identified first as a orthologue of C elegans UNC-76 protein, that plays functions related to neuronal development in this worm. Subsequent studies, shows FEZ1 functions in neuronal development process, cell polarization, transport mechanisms associated to kinesins and vesicular and mitochondrial transports. Other works showed that FEZ1 superexpression interfere in the life cycle of some viral types such as HIV and JCV. FEZ1 is able to interact with more than 51 different proteins and participates in several cellular processes. We observed that FEZ1 has a mobile molecular structure, is a member of the natively unfolded protein class, and can form dimers in solution. This observation is in agreement with its capacity to interact with a large number of different proteins. The capacity of FEZ1 to interact with other proteins is influenced by different PKC isoforms phosphorylation in its C-terminal region. FEZ1 interacts and co-localizes with NEK1 and CLASP2 in a centrossomal candidate region of mammalian cells. These interactions are dependent of a coiled coil inside the C-terminal region of FEZ1, and occur in dependence of coiled coil regions of NEK1 and CLASP2. The interaction between FEZ1 and CLASP2 is abolished after FEZ1 phosphorylation by PKC. The FEZ1 overexpression causes the flower like phenotype observed in cells of some leukemias. We observed that FEZ1 interacts and co-localizes with _ and _-tubulins and that the phenotype formation in HEK293 cells is mediated by an atypical organization of microtubule spindles, caused by overexpression of FEZ1. The flower like phenotype formation is influenced by activation of PKC and PI3K pathways. The data generated by our work indicate that FEZ1 is an intrinsically unfolded protein, that works in cellular processes associated to the cytoskeleton in conjunct with NEK1 and CLASP2, and that defects in its regulation, maybe via the PKC or PI3K pathways, causes alterations in microtubule organization and formation of the "flower like" nuclei. (AU)