Quintyne, Nicholas

Prostate cancer has the second highest mortality rate of all cancers in men. The Myc oncoprotein is misregulated in 70% of all cancers, including 70% of prostate cancers, and affects several cancer mechanisms. Myc is able to directly repress the expression of Tristetraprolin (TTP). TTP regulates mRNA stability by binding to select mRNAs.
Furthermore, TTP is able to suppress Myc‐driven B cell lymphoma in mice. In these
studies, cell culture models were used to access the role of Myc-induced repression of
TTP in prostate cancer. Prostate cancer cells lines were identified with inverse expression of Myc and TTP. Additionally, ARE‐containing genes with roles in various cancer mechanisms were differentially expressed in these models. These findings suggest that Myc’s ability to downregulate TTP is important in prostate cancer and provide new avenues for treating Myc‐driven prostate cancer.

The kinesin superfamily of microtubule motors is subdivided based upon structure and function. KIF9 is a member of the largely uncharacterized Kinesin-9 family. It was originally identified by sequence homology to other kinesins. Subsequent studies have indicated that KIF9 interacts with proteins involved in cell shape remodeling and cell migration. We have examined KIF9 function in mammalian cells using siRNA-mediated knockdown. By knocking down KIF9 expression in these cells, we have seen several effects on normal cell cycle progression. We have observed a decreased mitotic index, suggesting cells either fail to enter mitosis or abort the process prior to completion. Of the cells in that population that enter mitosis, we see a decrease in the number of cells in anaphase and telophase. Multinuclearity is greatly increased, indicating failure of cytokinesis. Interphase cells show decreased microtubule organization. We propose that KIF9 is important for normal completion of mitosis by regulating the contractile ring.

Vesicular transport is vital to the living cell. Motor proteins, such as the
kinesin superfamily proteins (KIFs), travel along microtubules with attached
vesicles to achieve vesicular transport (Hirokawa 2008). However, not all kinesins
participate in vesicular transport, some are required for other cellular functions. A
recent study showed that the KIF9 motor is involved in keeping the microtubule
organization center (MTOC) correctly positioned and oriented in Dictyostelium
(Tikhonenko et al., 2009), suggesting it may be involved in non-transport
functions. By modulating protein expression levels of KIF9 in COS7 cells, this
study aims to determine whether or not KIF9 contributes to vesicular motility.
Using a fluorescent dye, we have been able to track lysosome movements in
living cells. Our analysis has shown that decreasing KIF9 expression has no effect
on the velocity of vesicle motility, but does slightly affect processivity. This
suggests that KIF9 is not directly involved in cell motility, and serves another
function within the cell which may serve to decrease overall processivity.

The cytoskeleton is composed of dynamic polymers of actin, tubulin, and intermediate filaments. These proteins are responsible for maintaining cell shape, intracellular organization and transport, cell division, and many other cellular processes. Among the cytoskeletal interacting proteins are septins, a conserved family of GTP binding proteins that polymerize into higher ordered filaments. Septins interact with and regulate the dynamics of both actin and microtubule cytoskeletons. Septins also regulate the processes of cytokinesis and exocytosis. In this study we use COS-7 cells as a model for studying the localization, interaction, and dynamics of SEPT2 and SEPT7. We demonstrate that septins form filaments that colocalize with actin filaments in the cell periphery. Further, we show that actin filaments, but not microtubules, are required for formation of septin filaments in vivo.

Dynactin is a 1.2 MDa multisubunit complex that is involved in a variety of cellular functions including vesicle motility, microtubule organization, and cell division. The function of most dynactin subunits are at least partially characterized, with the exception of p24. Very few things are known about p24: it has a molecular weight of ~20,800 Da, is mostly α-helical, is only found in dynactin and binds directly to p150Glued. We are using overexpression, shRNA-mediated knockdown, and fluorescent microscopy, to determine a role for p24. When p24 is overexpressed, p150Glued is lost from the centrosome and Arp 1 remains, suggesting disruption of the complex. In addition, microtubule organization is disrupted. When p24 is knocked down, we retain p150Glued at the centrosome, along with Arp 1 and again see microtubule disorganization. These data suggest that p24 may act as an anchor to stabilize p150Glued when it binds to microtubules.

Ghrelin is a 28-amino acid peptide secreted by the stomach. Over the past decade,
studies have shown ghrelin to have broad effects on growth hormone release, appetite
regulation, and glucose metabolism. These effects are explained largely by the high
expression of the ghrelin receptor (GHS-R1a) in both the hypothalamus and pituitary.
Recently, ghrelin has been shown to have possible neuroprotective effects in other brain
regions expressing GHS-R1a, specifically stimulating anti-apoptotic and antiinflammatory
pathways. The endoplasmic reticulum (ER) is a cellular organelle
responsible for processing proteins. When an abundance of misfolded proteins
accumulate in the ER, cellular stress pathways ensue, and are linked to a number of
neurodegenerative diseases. This project will examine the effects of ghrelin during ER
stress in a human neuronal cell line. Expression of genes and proteins involved in
potential neuroprotective pathways will be examined to learn how ghrelin mediates its
anti-apoptotic effects in neurons.

Dynactin is made up of 11 different peptide units with a distinct ultrastructure consisting of a shoulder/sidearm complex and a rod-like domain. It functions as a cofactor for cytoplasmic dynein, assisting in the processes of long-range vesicle movements, microtubule anchoring, endomembrane localization, and mitotic progression. Previous studies have shown that dynactin binds to microtubules at the centrosome, keeping a radial arrangement during interphase. The p150Glued subunit contains two distinct microtubule-binding domains: CAP-Gly and Basic. While both of these sequences can interact with microtubules, CAP-Gly has a much greater affinity for binding to microtubules, suggesting that the two domains may be active for different functions within the cell. Using shRNA, I looked at the overexpression and knockdown of p150Glued and examined the effect that had on the cell. Knockdown has been shown to cause defects in centrosome organization and mitotic index.

The development of uterine cancer and its progression can be linked to external elements such as carcinogens, natural hormones and chemotherapeutic drugs. The goal of this project was to investigate the possible correlation between exposure to specific chemical and an increase of mitotic defects. These defects manifest themselves as lagging chromosomes, multipolar spindles, and anaphase bridges. Using the uterine cancer cell line MES-SA as a model, we established a baseline for the mitotic defects in the absence and presence of various chemicals using γ-tubulin and DAPI-immune stained fixed cells. The cells were treated with varying concentrations
of Vinyl Chloride, β-estradiol, Fluvestrant, and were examined using Immunofluorescent microscopy. We found that an exposure to Vinyl Chloride, β-estradiol and Fulvestrant have increased the number of mitotic defects in this cell line.

FAU's Office of Undergraduate Research and Inquiry hosts an annual symposium where students engaged in undergraduate research may present their findings either through a poster presentation or an oral presentation.

FAU's Office of Undergraduate Research and Inquiry hosts an annual symposium where students engaged in undergraduate research may present their findings either through a poster presentation or an oral presentation.