Functional characterization: the human kinase Nek5 interferes negatively in cell death and the polyglutamylation process

Author(s)

Talita Diniz Melo Hanchuk

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2015-05-03

Examining board members

Jörg Kobarg; Guido Lenz; Marcio Chaim Bajgelman; Carmen Veríssima Ferreira; Fernanda Ramos Gadelha

• Advisor: Jörg Kobarg

Abstract

Members of the Nek Family are crucial for the initiation of mitosis eukaryotes. All 11 human Neks have been functionally assigned to one of the three core functions established for this family in mammals: (1) centrioles/mitosis; (2) primary ciliary function/ciliopathies; and (3) DNA damage response (DDR). In the core section of the review (article I), we report the current detailed functional knowledge on each of the 11 Neks. We raise the hypothesis that Neks may be the connecting regulatory elements that allow the cell to fine tune and synchronize cellular events. Nek5 is the most neglected among members of the Nek kinases family. A yeast two-hybrid (Y2H) screen was performed to identify and characterize Nek5 interaction partners and mitochondrial proteins were retrieved (article 2). Apoptosis assay showed protective effects of hNek5 over-expression from Hek293-T¿s cell death after thapsigargin treatment (2 ?M) as well as an increase in ROS formation after 4 hours of treatment. Mitochondrial respiratory chain activity was found decreased upon hNek5 over-expression especially at the electrons transfer steps from TMPD to cytochrome c and at the complex II. The yeast two-hybrid allowed also the identification o TTLL4 as a Nek5 partner (article 3). Nek5 silenced cells as well as cells expressing a "kinase dead" version of Nek5, displayed an increase in polyglutamylation of proteins after TTLL4 transfection by western blot and in vitro polyglutamylation activity assay. In conclusion, our data suggest for the first time mitochondrial localization and functions for Nek5 and its participation in cell death and cell respiration regulation. This work also showed the function of Nek5 in the polyglutamylation process decreasing the role of TTLL4 through inhibitory phosphorylation by Nek5 (AU)

• FAPESP's process: 10/16831-0 - Functional Characterization: The human kinase Nek5 interferes negatively in cell death and the polyglutamylation process
• Grantee: Talita Diniz Melo Hanchuk
• Support Opportunities: Scholarships in Brazil - Doctorate