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Two sides of the plant nuclear pore complex and a potential link between ran GTPASE and plant cell division

Xu, Xianfeng
http://rave.ohiolink.edu/etdc/view?acc_num=osu1190050471

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Plant Biology.
Recent studies have indicated that the plant nuclear pore complex (NPC) plays important roles in several processes, including plant-microbe interactions, hormone signaling, and stress tolerance. However, both the protein components of and the various activities associated with the plant NPC are poorly understood. Here, I focused on analyzing two plant NPC-associated proteins located at opposite sides of the NPC. First, I identified an Arabidopsis protein called NUCLEAR PORE ANCHORE (NUA) as the homolog of mammalian Tpr, yeast Mlp1/Mlp2, and Drosophila Megator, long coiled-coil proteins associated with the inner basket of the NPC and involved in mRNA export, telomere organization, spindle pole assembly, and unspliced RNA retention. Four T-DNA insertion mutants of nua were identified, which comprise an allelic series with increasing severity for several correlating phenotypes, such as early flowering, increased abundance of SUMO conjugates, and altered expression of flowering regulators. Together with the genetic interaction between NUA and ESD4 (a SUMO protease), these data suggest that NUA is a conserved component of NPC-associated steps of sumoylation in plants. Defects in SUMO homeostasis affect signaling events of flowering time regulation and additional developmental processes. Secondly, I identified a plant-specific family of NPC-associated membrane proteins, WPP domain-interacting proteins (WIPs), which bind to the WPP domain of Arabidopsis Ran GTPase-activating protein RanGAP and are responsible for the NPC-association of RanGAP. Mammalian RanGAP targeting to NPC during interphase and to kinetochores during mitosis requires interaction of its sumoylated C-terminal domain with nucleoporin Nup358/RanBP2. In contrast, I demonstrated that binding to the coiled-coil domain of WIP is a plant-unique mechanism for targeting RanGAP to the NPC. Moreover, I presented data to suggest that the targeting of plant RanGAP appears to involve different mechanisms during different stages of the cell cycle and in different tissues. Taken together, my research demonstrates the involvement of NUA in regulating SUMO homeostasis and plant development and supports an independent evolution of RanGAP targeting - and thereby the spatial positioning of the Ran cycle - in different kingdoms. The conservation of NUA and the uniqueness of RanGAP anchoring illustrate that evolutionarily the plant NPC is both conserved and diversified.
Iris Meier (Advisor)
Nuclear Envelope (NE); Nuclear Pore Complex (NPC); Ran GTPase; Cell division; SUMO; flowering; plant development

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Citations

  • Xu, X. (2007). Two sides of the plant nuclear pore complex and a potential link between ran GTPASE and plant cell division [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1190050471

    APA Style (7th edition)

  • Xu, Xianfeng. Two sides of the plant nuclear pore complex and a potential link between ran GTPASE and plant cell division. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1190050471.

    MLA Style (8th edition)

  • Xu, Xianfeng. "Two sides of the plant nuclear pore complex and a potential link between ran GTPASE and plant cell division." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1190050471

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.