Department

Department of Zoology & Physiology, Department of Molecular Biology

First Advisor

Dr. Jesse Gatlin

Description

In order to segregate chromosomes accurately during division, a cell must first assemble a bipolar mitotic spindle. This process is regula ted in part by chromatin - mediated signaling cues that affect microtubule dynamics and microtubule motor function. The best characterized and arguably most important chromosome - mediated signaling pathway involves the small GTPase Ran and the nuclear recept or protein importin β (the Ran pathway). In these experiments we tested the hypothesis that the Ran pathway regulates the function of cytoplasmic dynein, a microtubule motor protein known to be critical for bipolar spindle assembly. We first investigated the possible interaction between importin β and dynein by adding recombinant, His - tagged importin β to mitotic cell - free extracts derived from Xenopus eggs. Ni - NTA agarose magnetic beads were then used to separate importin β and associated proteins from the rest of the extract. Western analysis confirmed the presence of dynein in the eluted fraction, suggesting that importin β interacts either directly with dynein or indirectly via dynein - associated proteins. Although more studies are needed to determin e whether activation of the Ran pathway affects this interaction and/or dynein motor function, our preliminary data are the first to indicate a mitotic link between the Ran pathway and dynein.

Comments

Oral and Poster Presentation, Wyoming INBRE, UW Honors Program

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Determining the effects of chromatin - derived signals on dynein motor function during mitosis

In order to segregate chromosomes accurately during division, a cell must first assemble a bipolar mitotic spindle. This process is regula ted in part by chromatin - mediated signaling cues that affect microtubule dynamics and microtubule motor function. The best characterized and arguably most important chromosome - mediated signaling pathway involves the small GTPase Ran and the nuclear recept or protein importin β (the Ran pathway). In these experiments we tested the hypothesis that the Ran pathway regulates the function of cytoplasmic dynein, a microtubule motor protein known to be critical for bipolar spindle assembly. We first investigated the possible interaction between importin β and dynein by adding recombinant, His - tagged importin β to mitotic cell - free extracts derived from Xenopus eggs. Ni - NTA agarose magnetic beads were then used to separate importin β and associated proteins from the rest of the extract. Western analysis confirmed the presence of dynein in the eluted fraction, suggesting that importin β interacts either directly with dynein or indirectly via dynein - associated proteins. Although more studies are needed to determin e whether activation of the Ran pathway affects this interaction and/or dynein motor function, our preliminary data are the first to indicate a mitotic link between the Ran pathway and dynein.