Ms. Paola Castro
Mentor: Dr. Steven Clarke
Title: The effects of oxidative stress on protein-repair deificient worms and the role of protein arginine methyltransferases in autoimmune diseases
(Shilpi Kare, Paola Castro, Dr. Steven Clarke)
Paola Castro is a third year student majoring in Biochemistry. She is a first year MARC student and is currently working in a Biochemistry lab where protein repair and aging is studied. She started as member of the Clarke lab on summer 2008 under the supervision of Shilpi Khare and Dr. Steven Clarke.
The loss of function in an aging organism can be due to spontaneous damage to proteins. Two major contributors to the loss of molecular function are oxidative damage and non-oxidative damage. Organisms can respond to molecular damage with repair and replacement or by preventing oxidative damage. To understand the mechanisms of damage and repair in aging, Paola has focused on an invertebrate model of aging, the nematode worm Caenorhabditis elegans. Oxidative Stress resistance and longevity in C. elegans is regulated by an insulin-like signaling pathway designated DAF-2. Down regulation of this pathway turns on genes regulated by DAF-16 that are responsible for preventing oxidative damage. Interestingly, Paola’s laboratory has found that a non-oxidative damage/repair pathway is also associated with the DAF-2 signaling pathway. The Clarke laboratory focus is the L-isoaspartyl-methyltransferase which methylates and targets non-oxidative damaged aspartyl residues for repair. This enzyme is encoded by the pcm-1 gene in C. elegans. Over expression of pcm-1 in C. elegans results in an extension of adult life span potentially via down regulation of the DAF-2 pathway. Furthermore, a pcm-1 deletion mutant shows increased sensitivity to oxidative stress. In this study, Paola began the investigation of the link between oxidative damage, aspartyl residue damage, and the DAF-2 signaling pathway with the possibility of life extension with antioxidants such as vitamin C. In the future, Paola will compare the effects of vitamin C on oxidatively-damaged wild type, pcm-1 deletion mutant and pcm-1 over expression worm strains. Paola will also study the effects of vitamin C on the DAF-2 signaling pathway, with a particular focus on DAF-16 because it regulates oxidative stress resistance.
Back to top
Ms. Michelle Crespo
Mentor: Dr. Carlos Portera-Cailliau
Title: Correlating Abnormal mGluR Signaling to Dendritic Spine Defects in Fragile X Mice
(Michelle Crespo and Dr. Carlos Portera Cailliau)
Michelle Crespo is a third year Neuroscience major and Biomedical Research minor. She began conducting research in the laboratory of Dr. Carlos Portera-Cailliau in spring of 2007. She is currently a first year MARC student and is a past participant of PEERS and the Amgen Scholars Program.
The project Michelle is involved in specifically focuses on the period of synapse formation in the neocortex and how it is disrupted in Fragile X syndrome (FXS), the most common inherited form of mental retardation and autism. The brains of individuals affected with FXS, as well as mutant mice lacking the Fmr1 gene (Fmr1 KO), contain abnormally long and thin dendritic spines that resemble their immature counterparts, dendritic filopodia. Observed differences in length, density, and dynamics of protrusions in Fmr1 KO mice might lead to early synaptic abnormalities since they occur during the first two postnatal weeks. Fragile X mutant mice also exhibit abnormal metabotropic glutamate receptor (mGluR) signaling, which is normally involved in learning and memory. Using acute slices, Michelle is investigating whether the increased spine length seen in Fmr1 KO mice is associated with enhanced mGluR signaling. She utilizes techniques such as in utero electroporation and two-photon imaging of layer 2/3 pyramidal cells to reveal more about the relation between structural and functional abnormalities in Fmr1 KO mice during development.
Back to top
Mr. Sergio Davila
Mentor: Dr. Genhong Cheng
Title: Role of Interferon Regulatory Factors 3 and 7 with Small Ubiquitin-like Modifiers in the Activation and Regulation of the Innate Immune System
(David Sanchez, Sergio Davila and Dr. Genhong Cheng)
Sergio J. Davila is a third year student majoring in Molecular and Cell Developmental Biology. He is a first year MARC student working in an Immunology laboratory where research is conducted on the innate and adaptive immune responses in host defense against bacterial and viral infections. He participated in PEERS and CARE Scholars prior to his entry into MARC and is planning to apply to a Ph. D. program in Biomedical research. He entered Dr. Cheng's laboratory fall quarter of his second year and works under the supervision of his mentor Dr. David J. Sanchez.
Interferon regulatory factor 3 (IRF-3) and IRF-7 are regulatory proteins in the immune system crucial for the protection of an organism against viral infections. They reside in the cytoplasm and are activated by phosphorylation when Toll-like receptors or retinoic acid inducible gene I–like helicases recognize a virus infecting the cell. Once activated, IRF-3 and 7 translocate to the nucleus and initiate transcription of Type I Interferon (IFN-1). A cascade commences causing cellular responses such as the induction of apoptosis upon viral infection as well as signaling surrounding cells of viral presence. Our major goal is to understand how the IFN-1 response is turned off. We have hypothesized that the IRFs’ induction of IFN-1 activity is stopped or down regulated by SUMOylation at yKXE motifs. To test this hypothesis, a site directed mutagenesis approach, K152R in IRF-3 and K406R in IRF-7, was undertaken. In theory, the replacement of lysine with arginine should not cause defective IRF proteins or SUMOylation on IRF-3 or 7. Ultimately, we will observe when the wildtype and mutant IRFs are SUMOylated. Since mutant IRFs will not have a SUMOylation site, the production of IFN-1 should be activated and be found at high levels with or without the SUMO protein. Conversely, the wildtype IRFs should decrease production of IFN-1 when the SUMO protein is added since they have a SUMOylation site. Our understanding of the IFN-1 deactivation process is very important to the development of novel antiviral drugs.
Back to top
Mr. Ryan Dosumu-Johnson
Mentor : Stephanie A. White
Research Title : Stress Levels Associated with Routine Behavioral Experiments in Birdsong Research
(Ryan Dosumu-Johnson and Dr. Stephanie White)
Ryan Dosumu-Johnson is a senior majoring in Neuroscience and a 1st year MARC student. He recently transferred from Orange Coast College to UCLA during the fall of 2006. Ryan was introduced to laboratory research at UCI through the MSP’s Bridge to the Baccalaureate summer research program. Through the connections he made at UCI he was advised to apply for the MARC fellowship program at UCLA and to speak with Dr. Stephanie A. White about her research. Because of this he began working in Dr. White’s lab in the spring of 2007 and shortly after was accepted into the MARC fellowship program.
Ryan is currently working with zebra finches, which are a good model for studying learned vocalizations, similar to human speech. To do this his project is focused on genetically modifying the well-characterized songbird circuit in hopes of elucidating a better understanding of the function of cells in certain nuclei. The ultimate goal of the project is to express or inhibit the expression of molecules of interest, like FoxP2. FoxP2 is currently the only protein to be directly linked to speech. This is of interest because modification of this molecule in the songbird circuit could help solidify the songbird as a good model organism for studying speech and provide a deeper understand of FoxP2’s role in speech. Previous work done by Ryan on the effect of the effect of common experimental trials on stress levels has been submitted for publication.
Back to top
Mr. Joseph Hargan Calvopina
PI: Dr. Hong Wu
Post Doc: Dr. Reginald Hill
Project: Exploring the role of PTEN in pancreas tumorigenesis
(Dr. Hong Wu, Joseph Hargan Calvopina and Dr. Reginald Hill)
Joseph Hargan Calvopina is a third year student majoring in Microbiology, Immunology, and Molecular Genetics. He is a first year MARC student and currently works in the department of Molecular and Medical Pharmacology. Joseph entered the lab fall quarter of his junior year and is under the supervision of Dr. Hong Wu, and Dr. Reginald Hill.
The PTEN controlled signal pathway is responsible for regulating cellular processes crucial for normal development, including cell proliferation, soma growth, cell death, and cell migration. It is a gene that has been found to be frequently mutated in human tumors. Through the use of a mouse model containing a PTEN deletion along with the over expression of KRAS G12D, an oncogene, Dr Hill’s research deals with identifying possible pathways that lead to pancreatic tumorigenesis. Through western blotting Joseph has been helping DR. Hill identify the possible over expression, or lack thereof of certain proteins that might be involved in the development of Pancreatic Ductal Adenocarcinoma(PDAC). Through immunohistochemistry it has also been possible to identify certain markers, and proteins that could also be responsible for the development of PDAC, including the possible role of Cox-2 in the inflammatory response that can be responsible for creating a microenvironment suitable for pancreatic lesions. The project seems to be moving in many different directions, including the possible role of immune response regulation playing a part in PDAC, as well as the possible role certain chemokines may have in metastasis.
Back to top
Ms. Erin Jimenez
Mentor: Dr. Carla Kohler
Title: AKT Localizes to the Intermembrane Space in Mammalian Mitochondria
(Dr. Susan Walsh and Erin Jimenez)
Erin Jimenez is a senior transfer student from Santa Monica College. She is a 1st Year MARC Trainee and is majoring in MCDB. She joined Carla Koehler’s lab in the summer of 2007 after participating in the Bridge Summer Program for Community College students. She is supervised by Dr. Susan Walsh.
Recent studies have identified new pathways in the mitochondrial intermembrane space (IMS), including an oxidative folding pathway for the import of proteins and phosphorylation-dependent signaling. We are investigating the kinase AKT (also known as Protein Kinase B), a major serine/threonine kinase regulated by extracellular and intracellular signaling pathways and capable of inducing pro-survival and proliferative effects. Substrates of AKT include a number of signaling proteins, such as transcription factors, apoptotic machinery, and components of glycogen metabolism. Previously, it was reported that a fraction of the total cellular AKT localizes to the mitochondria in tissue culture. We have shown that, though it is present in both mouse brain and liver tissue, AKT only localizes to mitochondria isolated from the brain. Furthermore, the fraction of AKT in the mouse brain mitochondria is active, localizes to the IMS, and may be loosely membrane-associated facing the IMS. This is in contrast to previously published data that suggests AKT localization to the mitochondrial membranes and matrix of tissue culture cells. We are currently investigating the mechanism of AKT import into the mitochondrion and the mitochondrial substrates and interacting proteins of AKT. This line of research will provide insight into AKT regulation and its cellular effects as well as a greater understanding of signaling pathways in the mitochondrial intermembrane space.
Back to top
Mr. Jason Melehani
Mentor: Dr. Kent Hill
Title: Proteomics based approach to characterize the role of the T. brucei flagellum in signal transduction and sensing the environment
(Dr. Kent Hill and Jason Melehani)
Jason Melehani is a third year Microbiology, Immunology and Molecular Genetics major at UCLA. This is his first year as part of the MARC program but it is his third year conducting research in the Hill lab. The Hill lab focuses on understanding the African trypanosome flagellum. Initial trained by Dr. Zakayi Kabututu, Jason has gained a broad skill set and has taken on his own project.
The African trypanosome, T. brucei, is the causative agent of African sleeping sickness, an epidemic disease in central Africa. T. brucei is a single cell parasite with a flagellum attached along the length of its body which it uses to drive motility. Unlike many organisms, the trypanosome flagellum leads the cell as it moves. The flagellum is also used for attachment to the tsetse fly salivary epithelium which is required for maturation as well as reinfection of a mammalian host through a blood meal. Additional, the flagellum is thought to play a role in sensing where the trypanosome extravasates so that it enters the brain and cerebral spinal fluid. The mechanisms by which these two events occur are unclear. In many organisms, flagella and cilia have been shown to be involved in sensing the environment and signal transduction. In C. reinhardtii, the flagella of two individuals intertwine during the mating process before genetic exchange occurs. In sperm, the activity of the flagellum is regulated in response to environmental stimuli. The human cilium is sometimes used for mechanosensing and has been shown to contain components of the hedgehog and Wnt signaling pathways. In order to identify signal transduction components and proteins involved in sensing the environment I have begun with a proteomic analysis of the flagellum. By isolating the trypanosome flagellar skeleton and analyzing it by MudPIT mass spectrometry, we have identified potential flagellar signal transduction proteins. Currently, my work focuses on localizing these candidate proteins and characterizing the role they play in the flagellum.
Back to top
Ms. Lan Huong Lai
Mentor: Miguel Garcia-Garibay
Research Title: Crystalline Molecular Machines: Design Influences on Solid-State Dynamics in Amphidynamic Materials
(Lan Huong Lai and Dr. Miguel Garcia-Garibay)
Lan Huong Lai was born in Saigon, Vietnam and moved to the US in 1994. She grew up in La Puente, California. She works in Professor Miguel Garcia-Garibay’s lab, a physical organic chemistry lab. One of the major focuses of the Garcia-Garibay lab is the study of structural influences on amphidynamic crystals, materials with both dynamic and static parts. Ms. Lai hopes to attain a BS in biochemistry and then go on to attain a PhD in organic chemistry.
Abstract: The purpose of our research is to study the solid-state dynamics of molecular gyroscopes in hopes of understanding how different topologies affect motion in the solid state. Previous studies in our group have shown that the dynamics of rotation of molecular gyroscopes becomes more favorable (i.e. faster) with decreasing packing coefficients, which can be achieved by increasing the steric bulk of the stator, the static portion of the molecule. In an effort to explore the effects of increased stator size and shape on the solid-state dynamics of these crystalline molecular machines, a molecular gyroscope with much larger “exploded” stators was synthesized by a series of Grignard (72.1%), Sonogashira cross coupling (47.5%), and organolithium (70.8%) reactions. We are currently attempting to synthesize deuterated analogues of the target gyroscope in order to study the dynamics in solid-state.
Back to top
Ms. Ekeoma Nwadibia
Mentor: Joan Valentine
Research Title: The Effect of Zinc-Binding on Human Wild-type SOD1 Reduction Kinetics
Ekeoma Nwadibia is a junior Chemistry major who started as a freshman at UCLA in fall 2005. She is a past participant in the PEERS program and BISEP. She joined Dr. Joan Valentine’s lab in the summer of 2007.
Abstract: Copper-zinc superoxide dismutase (CuZnSOD1) is a metal-bound dimeric antioxidant protein that catalyzes the disproportionation of superoxide anions. Copper is the catalytic site for dismutation of superoxide anion, while zinc provides structural stability. Though, SOD1 is present in the reducing environment of the cytosol, it has two oxidized cysteines that form an intermolecular disulfide bond, in addition to two reduced cysteines. Metal occupancy, oligomeric status, and the status of the disulfide bond, are tightly coupled in SOD1, and recent studies have shown that the binding of even one equivalent of zinc to SOD1 stabilizes the protein. Hence, I am studying both the rate of reduction and the reduction potential of the disulfide bond in SOD1. This study involved the use of metal-free (apo) SOD1 in optimizing the methods for which the quantification of disulfide bond reduction in SOD1 could be made. Metal-free SOD1 was reduced using dithiothreitol (DTT), and alkylated using 4-acetamido-4’-maleimidylstilbene-2,2’-disulfonic acid (AMS), which reacts with free thiols (reduced cysteines). Both reverse phase high-performance liquid chromatography (RP-HPLC) and SDS-PAGE were used to monitor the rate of disulfide bond reduction and thus quantitate the amounts of reduced and oxidized forms of SOD1. Alkylation with AMS seems effective in the quantification of reduced and oxidized SOD1, as indicated by mass spectrometry, and so will be standardized for future studies. Quantification of reduced and oxidized SOD1 will allow continued studies of zinc binding on the reduction kinetics and reduction potential of the disulfide bond in human wild-type SOD1, as well as mutant SOD.
Back to top
Ms. Maylen Perez
Mentor : Peggy Fong
Research Title : Drag and sediment scouring by tidal flow limit Enteromorpha intestinalis bloom formation in Carpinteria Salt Marsh
(Maylen Perez and Dr. Peggy Fong)
Maylen Perez is a junior Biology major. While in high school Maylen volunteered at a lab at Cal State Los Angeles. She started as a freshman at UCLA in fall 2005. She joined Dr. Peggy Fong’s lab in 2007.
Abstract:The biodiversity and dynamics of estuaries are greatly affected by eutrophication (the excessive accumulation of organic matter). Although we know excessive nitrogen loading stimulates algal blooms, other factors that limit algal blooms are poorly understood. Previous work suggested that water flow might limit Enteromorpha intestinalis blooms that occasionally obstruct habitat quality for other species in estuaries. We hypothesized that 1) water flow removed algae from the surfaces they attached to, 2) tall filaments would be dragged and removed more than short filaments and 3) E. intestinalis removal was due to sediment scouring by water flow as well as drag. We tested the effect of the two water flow regimes on short and tall algae attached to tiles (drag only) and to sediment cores (drag + scouring). Tiles and cores were photographed before and after each experiment and analyzed digitally for initial and final percent algal cover. We calculated percent removal as final percent cover minus initial percent cover. Sediment cores showed greater percent removal than tiles, demonstrating both drag and scouring of sediments are important in limiting algal blooms. In both tiles and cores, there was greater removal of short filaments than long filaments, suggesting both drag and scouring were more important in the initial stages of algal bloom development than in the later stages when algae are stronger and thus more resistant to both scouring and drag. Identifying the role of water flow speed on algal removal is important in understanding algal blooms.
Back to top
Mr. Richard Rodriguez
Mentor: Dr. Tomas Ganz M.D., Ph.D
Title: Elucidating the Human Iron Regulation Mechanism
(Richard Rodriguez, Dr. Tomas Ganz and Emilio Ramos )
Richard is a 3rd year Microbiology, Immunology, and Molecular Genetics Major, and is beginning his first year as a MARC trainee. Due to his own personal interest in hematology and biomedical science, the lab of Dr. Ganz seems an excellent fit. The Ganz Lab works in a variety of medical fields, including hematology and immunology. One major interest of the lab is iron homeostasis, the dysregulation of which results in serious conditions ranging from anemia (iron deficiency) to hemochromatosis (iron overload). In the Ganz lab Richard is supervised by graduate student Emilio Ramos.
Hepcidin, a hepatic hormone, is believed to be responsible for the regulation of iron levels in the serum and stores in organs. Normally, hepcidin regulates iron by stimulating internalization and degradation of ferroportin- the transmembrane protein which allows iron to exit cells and enter circulation. As hepcidin expression increases, iron levels decrease. In vivo experiments have revealed much about hepcidin's effects; however, in vitro experiments must be performed in order to reveal the mechanism of hepcidin regulation. In acute iron sensing (that is, iron sensing during a short term), the HFE and TfR2 proteins are thought to be central in iron sensing and stimulation of hepcidin expression through the BMP receptor pathway. We are currently attempting to replicate the mechanism for hepcidin regulation by iron in the Hep3B cell line which will be transfected with normal or mutant HFE and TfR2 constructs, and possibly different BMP receptors. Additionally, we will analyze the molecular interactions between HFE, TfR2 and members of the BMP receptor family in an effort to define the iron sensing complex that regulates hepcidin expression. A future experiment is to elucidate the mechanism for chronic iron sensing (iron sensing and regulation over the long term). Our findings may improve our understanding of the pathogenesis of hemochromatosis and could lead to novel treatment of iron metabolism disorders.
Back to top
