Caractérisation de la famille des protéines Kinases de type NIMA chez les plantes et analyse fonctionnelle de PNek1, une NEK du peuplier (Populus tremula X P. Alba clone 717 I-B4)

Authors: Vigneault, Frédéric
Advisor: MacKay, John; Séguin, Armand
Abstract: The NIMA-related kinases family (Neks) is well conserved among eukaryotes. Several studies, especially on Aspergillus nidulans NIMA and mammalian Nek2, have tagged them as cell cycle regulators. The objective pursued in this work was to characterise the plant Nek family and, more specifically, to identify a possible role for PNek1, a Nek from poplar tree. Here, I describe nine PtNeks in Populus trichocarpa, seven AtNeks in Arabidopsis thaliana and six OsNeks in Oryza sativa. Phylogenetic analysis in addition to their chromosomal distribution suggest a unique origin for all plant Neks. Exhaustive transcript expression analysis indicates that plant Neks regulation is related to the basipetal and vascular plant development patterns. Moreover, PNek1 promoter expression analysis reveals a striking similarity with sites of auxin production, basipetal leaf development and vascular initiation. However, PNek1 is not induced by auxin signalling. PNek1 overexpression in Arabidopsis induces severe inflorescence anomalies, which can lead to flower sterility. At the cell level, PNek1 is localised in the nucleoli and accumulates during the G2 phase before the onset for mitosis. PNek1 transcript accumulation could also be induced by a genotoxic stress at the G1/S checkpoint. Yeast two-hybrid experiments indicate that PNek1 could be involved in mRNA maturation since it interacts with DBR1, a protein directly involved in RNA splicing. This work offers a unique perspective to the actual Neks literature as cell cycle regulators. The particular biological context of poplar trees also brought me to associate Neks with complex organ development. This approach and these observations represent an original contribution, distinguishing itself from the numerous mammalians studies which only looked at their relation to the cell cycle regulation.
Document Type: Thèse de doctorat
Issue Date: 2009
Open Access Date: 16 April 2018
Grantor: Université Laval
Collection:Thèses et mémoires

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