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Knockdown of KIF9 leads to defects in mitotic entry and progression in mammalian cells
Title
Knockdown of KIF9 leads to defects in mitotic entry and progression in mammalian cells.
Creator
Alsina, Laura., Harriet L. Wilkes Honors College
Abstract/Description
Kinesin motors bind to microtubules and function in mitosis and intracellular transport depending on the position of the motor domain within the primary sequence (Hirokawa and Noda 2008). KIF9 has recently been shown to be involved in MTOC positioning and mitotic entry in Dictyostelium (Tikhonenko et al. 2009). To determine if a similar role for KIF9 exists in mammalian cells, we are using siRNA-mediated knockdown of KIF9 in COS-7 cells. Analysis of unsynchronized and cell-cycle synchronized...
Show moreKinesin motors bind to microtubules and function in mitosis and intracellular transport depending on the position of the motor domain within the primary sequence (Hirokawa and Noda 2008). KIF9 has recently been shown to be involved in MTOC positioning and mitotic entry in Dictyostelium (Tikhonenko et al. 2009). To determine if a similar role for KIF9 exists in mammalian cells, we are using siRNA-mediated knockdown of KIF9 in COS-7 cells. Analysis of unsynchronized and cell-cycle synchronized cells treated with siRNA to KIF9 reveal that the transition from G2 to M phase is delayed and that mitotic progression is also affected. Additionally, our data indicates that spindle pole function during anaphase may be abnormal in cells treated with siRNA, suggesting a role for KIF9 during that stage.
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Date Issued
2010
PURL
http://purl.flvc.org/FAU/3334255
Subject Headings
Cells, Motility, Protoplasmic streaming, Cell organelles, Formation, Cellular signal transduction
Format
Document (PDF)
Dynactin is a processivity factor for dynein in vivo
Title
Dynactin is a processivity factor for dynein in vivo.
Creator
Fulton, Edward., Harriet L. Wilkes Honors College
Abstract/Description
Dynein is a motor protein responsible for microtubule-based minus-end directed trafficking in eukaryotic cells. Dynactin is a protein complex involved in mitosis, embryonic development, intracellular trafficking and anchoring microtubules at the centrosome. While dynactin is widely recognized to improve the array of cargo with which dynein can associate, there has been some dispute over whether dynactin, which binds both dynein and microtubules, improves the distance that dynein can travel...
Show moreDynein is a motor protein responsible for microtubule-based minus-end directed trafficking in eukaryotic cells. Dynactin is a protein complex involved in mitosis, embryonic development, intracellular trafficking and anchoring microtubules at the centrosome. While dynactin is widely recognized to improve the array of cargo with which dynein can associate, there has been some dispute over whether dynactin, which binds both dynein and microtubules, improves the distance that dynein can travel processively in the act of cargo trafficking before it dissociates from its microtubule. In this study, we compare movement parameters of wild type dynein-based vesicle movements with movements in cells where expression of dynactin's microtubule binding subunit, p150glued, has been knocked down. We find that dynactin does act as a processivity factor for dynein by increasing the distance that dynein can travel smoothly in a single movement event, but does not increase dynein's velocity.
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Date Issued
2009
PURL
http://purl.flvc.org/FAU/209990
Subject Headings
Cell organelles, Formation, Microtubules, Cytoskeletal proteins, Molecular biology
Format
Document (PDF)
Characterization of the motor protein, KIF9, in mammalian cell mitotic progression
Title
Characterization of the motor protein, KIF9, in mammalian cell mitotic progression.
Creator
Hoke, Jordan, Harriet L. Wilkes Honors College
Abstract/Description
The kinesin family of microtubule motors is divided into subfamilies based on structure and function. KIF9, founder of the Kinesin-9 family, has been found to interact with the GTPase Gem. Subsequent studies have shown that KIF9 is vital for flagellar movement and podosome regulation. Previous work has proposed KIF9 is required for microtubule organization as well as proper mitotic entry, progression and completion. In this study, I examined the function of KIF0 in mitotic progression using...
Show moreThe kinesin family of microtubule motors is divided into subfamilies based on structure and function. KIF9, founder of the Kinesin-9 family, has been found to interact with the GTPase Gem. Subsequent studies have shown that KIF9 is vital for flagellar movement and podosome regulation. Previous work has proposed KIF9 is required for microtubule organization as well as proper mitotic entry, progression and completion. In this study, I examined the function of KIF0 in mitotic progression using shRNA-mediated knockdown, and overexpression. In knockdown cells, I saw a significant delay in mitotic progression as well as an increase in multipolarity and multinuclearity, suggesting a failure of cytokinesis. Overexpression of KIF9 produced similar effects on mitotic progression, as well as a marked increase in chromosome distance during anaphase. Taken with previous results, my research indicated that KIF9 is required for normal mitotic progression and completion, possible via regulation of the contractile ring.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3359298
Subject Headings
Cells, Motility, Protoplasmic streaming, Cell organelles, Cellular signal transduction, Cytoskeletal proteins
Format
Document (PDF)
Differential functionality of microtubule binding motifs in the p150[Glued] subunit of dynactin
Title
Differential functionality of microtubule binding motifs in the p150[Glued] subunit of dynactin.
Creator
Mallen, Michael Luis., Harriet L. Wilkes Honors College
Abstract/Description
Dynactin is a multi-subunit protein complex that is the required cofactor for the cytoplasmic motor protein, dynein. Dynactin is critical for cytoplasmic activities such as vesicle transport, cytoskeletal organization, membrane organization and mitotic progression as it serves to increase processivity of dynein. The main subunit in focus for this study is the sidearm extension p150Glued. On the exposed end (N-terminus) lie two different microtubule binding motifs: CAP-Gly and Basic. CAP-Gly...
Show moreDynactin is a multi-subunit protein complex that is the required cofactor for the cytoplasmic motor protein, dynein. Dynactin is critical for cytoplasmic activities such as vesicle transport, cytoskeletal organization, membrane organization and mitotic progression as it serves to increase processivity of dynein. The main subunit in focus for this study is the sidearm extension p150Glued. On the exposed end (N-terminus) lie two different microtubule binding motifs: CAP-Gly and Basic. CAP-Gly has a high binding affinity for microtubules, while Basic binds the microtubules quite weakly. It is at this location that dynactin is proposed to assist in the processivity of transporting cargo long distances in the cell, by providing additional support for the dynein molecule as it progresses along the microtubule. Analysis of the effects of overexpression of these motifs, alone or in tandem, suggested that there was no disruption of the dynein/dynactin interaction, but its ability to act in a processive manner had been perturbed. Effects on non-dynamic processes, such as Golgi localization and microtubule organization were generally weak, but effects were greater on y-tubulin organization. While this could suggest a defect in centrosome organization, we propose that it instead shows that cargo motility in the affected cells is defective, and that transport of centrosomal proteins to the centrosome is interrupted, suggesting a broader cargo-transport defect may be evident in these cells.
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Date Issued
2007
PURL
http://purl.flvc.org/FAU/11613
Subject Headings
Cytoskeletal proteins, Tubulins, Microtubules, Centrosomes, Cell organelles, Formation
Format
Document (PDF)
Centrosome recruitment
Title
Centrosome recruitment: analysis of protein changes during S phase.
Creator
Raborn, Erik., Harriet L. Wilkes Honors College
Abstract/Description
The centrosome is a dynamic and highly active organelle within the cell. It plays a pivotal role in mitosis driving several of the physical changes that are taking place. The centrosome self-replicates before mitosis in order to set up two spindle poles on opposite sides of the cell. This leads to the creation of a mother and daughter centrosomes within a cell that have distinct components. This project will examine the recruitment of proteins to the centrosome as a cell progresses through...
Show moreThe centrosome is a dynamic and highly active organelle within the cell. It plays a pivotal role in mitosis driving several of the physical changes that are taking place. The centrosome self-replicates before mitosis in order to set up two spindle poles on opposite sides of the cell. This leads to the creation of a mother and daughter centrosomes within a cell that have distinct components. This project will examine the recruitment of proteins to the centrosome as a cell progresses through the cell cycle. The proteins examined are (Sd(B-tubulin, (Sf(B-tubulin, Nek 2, Centrin2, p150Glued, EB-1, and dynein intermediate chain. In addition, chromosome arrangement was determined. By examining these proteins we hope to establish a logical order for the interactions of these proteins and their key contributions to cell cycle progression and completion, specifically dealing with the development of the mother and daughter centrosomes.
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Date Issued
2009
PURL
http://purl.flvc.org/FAU/3325085
Subject Headings
Cell organelles, Formation, Cytoskeletal proteins, Cell division, Tubulins, Microtubules
Format
Document (PDF)
Adopting the orphan: determining the role of the motor protein KIF9 during the cell cycle
Title
Adopting the orphan: determining the role of the motor protein KIF9 during the cell cycle.
Creator
Rivera Rios, Miguel E., Harriet L. Wilkes Honors College
Abstract/Description
The kinesin superfamily of microtubule motor proteins is subdivided into families based upon structure and function. KIF9 is the founding member of the Kinesin-9 family, which is a largely uncharacterized group of kinesins. It was originally identified by sequence homology to other kinesins. Subsequent studies have shown that KIF9 interacts with proteins involved in cell shape remodeling, cell migration and proper centrosomal positioning. We have examined KIF9 function in mammalian cells...
Show moreThe kinesin superfamily of microtubule motor proteins is subdivided into families based upon structure and function. KIF9 is the founding member of the Kinesin-9 family, which is a largely uncharacterized group of kinesins. It was originally identified by sequence homology to other kinesins. Subsequent studies have shown that KIF9 interacts with proteins involved in cell shape remodeling, cell migration and proper centrosomal positioning. We have examined KIF9 function in mammalian cells using shRNA-mediated knockdown and GFP-plasmid overexpression. By knocking dow KIF9 expression in these cells, we have seen several effects on normal cell cycle progression. Using various cell cycle markers, we have observed a decrease in the number of cells in late S phase. In addition, there is a marked increase in the number of cells in early mitosis in unexpected time intervals. We propose that KIF9 is required for proper cell progression, via a potentially novel checkpoint mechanism.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3359321, http://purl.flvc.org/fau/fd/FADT3359321
Subject Headings
Cell organelles, Formation, Cellular signal transduction, Protoplasmic streaming, Cells, Motility, Cell division, Research
Format
Document (PDF)
Knockdown of dynactin's p150[Glued] subunit abrogates microtubule organization
Title
Knockdown of dynactin's p150[Glued] subunit abrogates microtubule organization.
Creator
Roeckner, Jared Todd., Harriet L. Wilkes Honors College
Abstract/Description
Dynactin is a multifunctional protein complex composed of at least 11 different subunits. Dynactin functions as a cofactor for cytoplasmic dynein facilitating long-range vesicle movements, microtubule anchoring, endomembrane localization, and mitotic progression. Previous studies have shown that dynactin binds to microtubules at the centrosome maintaining a radial array in interphase. The p150Glued subunit contains two distinct microtubule-binding sequences named CAP-Gly and Basic. While both...
Show moreDynactin is a multifunctional protein complex composed of at least 11 different subunits. Dynactin functions as a cofactor for cytoplasmic dynein facilitating long-range vesicle movements, microtubule anchoring, endomembrane localization, and mitotic progression. Previous studies have shown that dynactin binds to microtubules at the centrosome maintaining a radial array in interphase. The p150Glued subunit contains two distinct microtubule-binding sequences named CAP-Gly and Basic. While both domains can interact with microtubule, CAP-Gly has a much greater affinity for binding to microtubules, suggesting that the two domains may be active for different dynactin-based functions within the cell. Using siRNA, we found that knockdown of p150Glued was sufficient to alter the maintenance of radial microtubule arrays, cause an increase in centrosome number and mitotic index. In the future we will replace the endogenous protein with versions lacking the CAP-Gly or Basic domains to investigate the contribution of each to microtubule anchoring and cytoskeletal architecture.
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Date Issued
2009
PURL
http://purl.flvc.org/FAU/209998
Subject Headings
Cytoskeletal proteins, Cell organelles, Formation, Microtubules, Molecular biology
Format
Document (PDF)
Contributions of dynactin's p150[Glued] subunit's binding domains to microtubule anchoring at the centrosome
Title
Contributions of dynactin's p150[Glued] subunit's binding domains to microtubule anchoring at the centrosome.
Creator
Schneider, Rebecca., Harriet L. Wilkes Honors College
Abstract/Description
Intracellular transport carries out very important roles within the cell including mitosis, organization, and organelle function. In order for effective transport using the motor protein dynein, a cofactor named dynactin is required. Of dynactin's many subunits, p150[Glued] holds the most responsibility for effective microtubule organization throughout the cell and the necessary anchoring at the centrosome. P150[Glued] holds two areas of high binding potential, the CAP-Gly region and the...
Show moreIntracellular transport carries out very important roles within the cell including mitosis, organization, and organelle function. In order for effective transport using the motor protein dynein, a cofactor named dynactin is required. Of dynactin's many subunits, p150[Glued] holds the most responsibility for effective microtubule organization throughout the cell and the necessary anchoring at the centrosome. P150[Glued] holds two areas of high binding potential, the CAP-Gly region and the Basic region. Each of these binding domains have different binding potentials and affinities for microtubules. The CAP-Gly region binds tightly the microtubules for a longer period of tiem ; the Basic region binds loosely to microtubules. Throughout the course of my research, I manipulated these two regions binding affinity for microtubules and evaluated the resulting cells ability to effectively organize microtubules and anchor them properly at the centrosome.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3359326
Subject Headings
Cytoskeletal proteins, Microtubules, Centrosomes, Cell organelles, Formation, Molecular biology, Tubulins
Format
Document (PDF)