Research projects in neuroscience, psychology and biology conducted by current students and recent alumni will be presented at the Robert B. Glassman Memorial Brain, Mind, and Behavior Symposium during Brain Awareness Week on Wednesday, November 13 at 5:45 p.m.
The following abstracts are arranged in alphabetical order of the presenting first author for each study.
Vulnerability of Attention: How Distractible Are You?
Belen Martinez-Caro Aguado, Naomi Wentworth
Department of Psychology, Lake Forest College
Effective perception of objects requires attention, but attention can be diverted when we are distracted. Theeuwes et al. (1999) demonstrated that the presence of additional items in our visual field is one factor that can make us more vulnerable to distraction. In this study, the added effect of movement on distraction was examined. The hypothesis is that the added movement will increase distraction as seen by slower reaction times to the target, and more erroneous eye movements to the distractor. There were significantly more eye movements towards the distractor in the movement condition compared to the no movement condition. These results show that the movement of the distractor had an effect on the attention of participants. Future studies would compare the effect of distractor speed on attention.
Neuropeptide Y1 receptor is a key element in stress response to food deprivation
Joseph Bortolotti, Janice H. Urban
Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, and Neuroscience Program, Lake Forest College
The hypothalamic-pituitary adrenal (HPA) axis functions as a default pathway for the maintenance of energy homeostasis. Food restriction or deprivation leads to prolonged HPA axis activation but the exact mechanism of this continuous HPA activation is not yet well understood. Our experiments were designed to determine whether neuropeptide Y (NPY) Y1 receptors participate in the stress response to food deprivation since NPY expression is elevated during periods of fasting. Food deprivation of male rats for 24 hours caused weight loss, adrenal gland hypertrophy and increased plasma ACTH and corticosterone concentrations. Food deprivation increased NPY mRNA expression in arcuate and brainstem C2/A2 nuclei that project to the hypothalamic paraventricular nucleus (PVN). While the total area of CRH mRNA positive cells in the PVN decreased during food deprivation, the CRH mRNA signal intensity increased in the remaining active cells. Food deprivation also increased pCREB-ir expression in PVN, an indication for neuronal activation. A majority of pCREB-positive cells were CRH/Y1-ir neurons. Infusion into the PVN of 1 nmol BIBP3226, a specific Y1 receptor antagonist, eliminated the elevated corticosterone blood levels in food-deprived animals.
Our observations support the notion that NPY Y1 receptors expressed by hypothalamic CRH neurons are pivotal for triggering a strong stress response during periods of food deprivation.
Neuroscience and Medical Mysteries of Sleep and Wakefulness
Trevor Buhr, Tiffany Davis, Schuyler Kogan, Al Tiba, Zachary Weinstein, Shubhik DebBurman
First-Year Studies Program, Lake Forest College
This first-year studies project from FIYS106 Medical Mysteries of the Mind will teach us about the fundamental biology and functional brain anatomy that underlies sleep and wakefulness and disorders that arise when the biology and anatomy are disrupted. Each member of this group will present a current medical mystery linked to this topic by summarizing a recently published major paper in this field.
Neuroscience and Medical Mysteries of Emotions
Marisol Carreon, Madison Copeland, Emma Levine, Junya Li, Agnieszka Pastwa, Mohini Verma, Shubhik DebBurman
First Year Studies Program, Lake Forest College
This first-year studies project from FIYS106 Medical Mysteries of the Mind will teach us about the fundamental biology and functional brain anatomy that underlies emotions and disorders that arise when the biology and anatomy are disrupted. Each member of this group will present a current medical mystery linked to this topic by summarizing a recently published major paper in this field.
Neuroscience and Medical Mysteries of Learning and Memory
Rachel Domijancic, Devon Hawkins, Nicole Hueng, Aasimah Tanveer, Rosemary Thomas, Shubhik DebBurman
First Year Studies Program, Lake Forest College
This first-year studies project from FIYS106 Medical Mysteries of the Mind will teach us about the fundamental biology and functional brain anatomy that underlies learning and memory and disorders that arise when the biology and anatomy are disrupted. Each member of this group will present a current medical mystery linked to this topic by summarizing a recently published major paper in this field.
Uncovering the contributions of amino domain and alternatively spliced varioants of a-SYNUCLEIN
in Parkinsons Disease: Insights from Yeast
Khadijah Hamid, Ana McCracken, Cam Gudmundson, Shubhik DebBurman
Neuroscience Program and Biology Department, Lake Forest College
Abstract: Parkinson’s disease (PD) is a hypokinetic neurodegenerative disorder characterized by the death of midbrain dopaminergic neurons. This cell death is linked to the accumulation of an aggregated protein, a-synuclein, which is 140 amino acids long (Syn140). This protein has three functional parts, one of them being the N-terminal domain (amino acids 1-60), which is associated with lipid binding. The amino acids within this domain that are critical for lipid binding are not clear. Moreover, three shorter alternatively spliced forms of a-synuclein (Syn126, Syn112, and Syn98) that are missing parts of the N-terminal and C-terminal domains were recently discovered in normal and PD patients; however their contributions to health and disease need further evaluation. This present study consists of two projects, both being evaluated in a budding yeast model for PD developed by the DebBurman lab: 1) characterization of the splice variant forms of a-synuclein, and 2) evaluation of N-terminal domain by creation of six truncation mutants. We have synthesized the three splice variants for yeast expression and are testing the hypothesis that they will contribute to PD, by decreasing membrane association (Syn126, Syn98) and solubility (Syn112, Syn98). We have also created six N-terminal truncation mutants (Syn10-140, Syn20-140, Syn 30-140, Syn40-140, Syn50-140 and Syn60-140) and are testing the hypothesis that specific smaller regions within the N-terminal domain govern lipid binding, protein aggregation, and toxicity of a-synuclein. Better understanding of the amino domain and the splice variants of a-synuclein will contribute to the overall understanding of PD pathogenesis.
Juvenile hormone regulates body proportion in drosophila
James Haney, Lauren Lyon, Chris Mirque, Alex Shingleton
Department of Biology, Lake Forest College
The shape of an organism is defined by the size of its individual body parts relative to each other and to the body as a whole. Because of the tight link between organismal form and function, the developmental regulation of body proportion is fundamental to generating a fully functioning adult. In order to generate a correctly proportioned adult, growth of individual organs and tissues must be coordinated across the body as a whole. This growth coordination is presumably hormonally regulated, and yet we have a very poor understanding of what these hormones are and how they work. Recently we have discovered a novel regulator of body proportion in Drosophila: Juvenile Hormone(JH). This hormone has historically been considered responsible for controlling the transition between the different stages in an insect’s life-cycle (larval, pupal, adult). However, our data indicate that flies mutant for the JH receptor, Met, show altered body proportion. Here we present data supporting the hypothesis that JH regulates relative organ size in Drosophila and that it does so via the hormone ecdysone.
Demographic Predictors of Barriers and Treatment Outcomes in Children with Inflammatory Bowel Disease
Alexa Hemmer, Rachel Neff Greenley
Department of Psychology, Rosalind Franklin University of Medicine and Science, and Neuroscience Program, Lake Forest College
Department of Psychology, Rosalind Franklin University of Medicine and Science, and Neuroscience Program, Lake Forest CollegeInflammatory bowel disease (IBD) is the inflammatory disease of the digestive track and occurs in 71 out of 100,000 children. As with most chronic illnesses, much work has been done to increase medication adherence in children with IBD. Problem Solving Skills Training is a cognitive behavioral intervention that is used to teach families how to properly identify and work through barriers to medication adherence. PSST has been shown to be effective with other pediatric populations with chronic illnesses, but until now, no research has been done to analyze what adherence barriers are most common among children with IBD and which barriers were best overcome using PSST. It was found that the most commonly endorsed barriers family functioning, knowledge, organizational, and social. Children were most involved when discussing organizational barriers and were not as involved when discussing knowledge-based barriers. Length of time since diagnosis had an effect on which barriers were discussed, as well as child involvement and satisfaction. Children who were diagnosed with IBD more recently more commonly discussed organizational barriers. Children who had been diagnosed with IBD longer were more involved and more satisfied than children who had more recent diagnoses.
Neuroscience Program and Department of Psychology, Lake Forest College
Kayla Huber, Susan Long
Neuroscience Program and Department of Psychology, Lake Forest College
Between 11.7 and 18 million American women will be subjected to a completed forceful sexual penetration within their lifetime (Basile, 2001-2003; Kilpatrick, 2007). The astoundingly high incidence of rape and sexual assault within the United States has motivated researchers and activists to create programs that may prevent the crime from occurring in the future. A one-day sexual assault prevention program for high school students living in a Midwestern suburban community was implemented and evaluated using a pretest-posttest design. Among the sample of students who received parental consent (N= 32), there were significant changes between pretest and posttest in desired directions in the three areas indicating a readiness to change (modified from Prochaska & DiClemente, 1992). There was a marginally significant difference between the gender egalitarian beliefs of males and females. In addition, females had significantly less bystander efficacy than males. In future studies, we wish to use a larger sample as well as model the relationship between variables such as empowerment, gender egalitarianism, bystander efficacy, and readiness to change.
Saccadic and Smooth-Pursuit Eye Movements and Working Memory
Kristina Karapetyan, Naomi Wentworth
Department of Psychology, Lake Forest College
One of the most fundamental questions in the study of human vision is how information accumulates across separate glances and when information is memorized. People make eye movements in order to select particular information of interest. The components of tracking eye movements include smooth-pursuit and saccadic eye movements. This study is an investigation of the relationship between saccadic and smooth pursuit eye movements and the number of words memorized. The purpose of this study is to determine what type of eye movements enhances the memorization process. The hypothesis states that saccadic eye movements enhance the memorization process. The results demonstrated that the average number of words memorized by using smooth pursuit and saccadic eye movements were similar. Also the study has shown that in the mixed block, the words presented in the smooth - pursuit manner were memorized better. In order to understand the relationship between eye movements and memorization some future studies may investigate how speed of smooth-pursuit eye movements affects memorization.
Neuroscience and Medical Mysteries of Sex and Sexuality
Adam Khan, Krista Meuli, Robin Redmond, Lucas Shylanski, Michael Tseitlin, Shubhik DebBurman
First Year Studies Program, Lake Forest College
This first-year studies project from FIYS106 Medical Mysteries of the Mind will teach us about the fundamental biology and functional brain anatomy that underlies sex and sexuality and disorders that arise when the biology and anatomy are disrupted. Each member of this group will present a current medical mystery linked to this topic by summarizing a recently published major paper in this field.
Developmental changes in the cochlear hair cell mechanotransducer channel and their regulation by transmembrane channel–like proteins
Lily Vedran ’17, Kyunghee X. Kim, Robert Fettiplace
Department of Neuroscience, University of Wisconsin-Madison, WI 53706
Neuroscience Program, Lake Forest College, Lake forest, IL 60045
Vibration of the stereociliary bundles activates calcium-permeable mechanotransducer (MT) channels to initiate sound detection in cochlear hair cells. Different regions of the cochlea respond preferentially to different acoustic frequencies, with variation in the unitary conductance of the MT channels contributing to this tonotopic organization. Although the molecular identity of the MT channel remains uncertain, two members of the transmembrane channel–like family, Tmc1 and Tmc2, are crucial to hair cell mechanotransduction. We measured MT channel current amplitude and Ca2+ permeability along the cochlea’s longitudinal (tonotopic) axis during postnatal development of wild-type mice and mice lacking Tmc1 (Tmc1−/−) or Tmc2 (Tmc2−/−). In wild-type mice older than postnatal day (P) 4, MT current amplitude increased ∼1.5-fold from cochlear apex to base in outer hair cells (OHCs) but showed little change in inner hair cells (IHCs), a pattern apparent in mutant mice during the first postnatal week. After P7, the OHC MT current in Tmc1−/− (dn) mice declined to zero, consistent with their deafness phenotype. In wild-type mice before P6, the relative Ca2+ permeability, PCa, of the OHC MT channel decreased from cochlear apex to base. This gradient in PCa was not apparent in IHCs and disappeared after P7 in OHCs. In Tmc1−/−mice, PCa in basal OHCs was larger than that in wild-type mice (to equal that of apical OHCs), whereas in Tmc2−/−, PCa in apical and basal OHCs and IHCs was decreased compared with that in wild-type mice. We postulate that differences in Ca2+ permeability reflect different subunit compositions of the MT channel determined by expression of Tmc1 and Tmc2, with the latter conferring higher PCa in IHCs and immature apical OHCs. Changes in PCa with maturation are consistent with a developmental decrease in abundance of Tmc2 in OHCs but not in IHCs.
Plasma membrane citrate transporter structure and inhibition
Kristofer Korth, Ronald Kaplan
Department of Biochemistry & Molecular Biology, Rosalind Franklin University of Medicine and Science, and Biology Department, Lake Forest College
Citrate is a primary component of the citric acid cycle also known as the tricarboxylic acid cycle (TCA). It allows for cells to generate adenosine triphosphate (ATP), the key form of chemical energy used by the body. When in excess, citrate is broken down into Acetyl coenzyme A (Acetyl-CoA) a precursor to fatty acid and cholesterol biosynthesis. There are two sources of cytoplasmic citrate the first being of mitochondrial origin and the second being from an influx of citrate across the plasma membrane through the use of the plasma membrane citrate transporter (PMCT). Past studies on Drosophila and C. elegans regarding the disruption of PMCT function have shown an increased life span in subjects. By determining the crystal structure of the PMCT, structure based inhibitors can be developed to prevent the influx of citrate into human cells. The reduction of cytoplasmic citrate can help to alleviate symptoms of obesity, hyperlipidemia, hypercholesterolemia, and Type 2 diabetes. The structure has yet to be determined but the significant role that the PMCT plays in the cell’s energy state makes it a relevant target for research.
Increased mtDNA mutations with aging promotes amyloid accumulation and brain atrophy in the APP/Ld transgenic mouse model of Alzheimer’s disease
Lokesh Kukreja,1* Gregory C. Kujoth,2 Tomas A. Prolla,2 Fred Van Leuven,3 and Robert Vassar1
1 Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine; 2 Departments of Genetics and Medical Genetics, University of Wisconsin, Madison; 3 Experimental Genetics Group-LEGTEGG, Department of Human Genetics, KU Leuven, Leuven, Belgium
*Dr. Kukreja graduated from Lake Forest College in 2008 with a biology major. He received his PhD in Biology from Northwestern University in 2014.
The role of mitochondrial dysfunction has long been implicated in age-related brain pathology, including Alzheimer’s disease (AD). However, the mechanism by which mitochondrial dysfunction causes neurodegeneration in AD is unclear. To model mitochondrial dysfunction in vivo, we utilized mice that contain knock-in mutation, inactivating the proofreading function of mitochondrial DNA polymerase γ (PolgA D257A), so that these mice accumulate mitochondrial DNA mutations with age. PolgA D257A mice rapidly develop a myriad of mitochondrial bioenergetic defects and physical phenotypes that mimic premature ageing, with subsequent death around one year of age. We crossed the D257A mice with a well-established transgenic AD mouse model (APP/Ld) that develops amyloid plaques. We hypothesized that mitochondrial dysfunction would affect Aβ synthesis and/or clearance, thus contributing to amyloidogenesis and triggering neurodegeneration. Initially, we discovered that Aβ42 levels along with Aβ42 plaque numbers were increased in D257A; APP/Ld bigenic mice compared to APP/Ld alone given that these mice expressed similar levels of APP transgene. An Aβ production increase appeared an unlikely explanation for the higher Aβ42:APP/Ld ratio, because the levels and activity of Aβ generating enzymes such as b-and g-secretase were unchanged in these mice. However, the levels of a major Aβ removal enzyme, insulin degrading enzyme, were lower with the D257A mutation than without, indicating a potential mechanism for increased amyloid load via reduced Aβ clearance from the brain. In the presence of the APP transgene, D257A mice also suffered from significant brain atrophy with apparent cortical thinning attributable to neuron loss. These bigenic mice had increased levels of activated caspase-3 and nuclei characteristically similar to apoptotic cells when compared to mice with either D257A mutation or APP transgene alone. Overall, our results suggest that there might be synergism between the effects of the PolgA D257A mutation and Aβ in causing neurodegeneration. These findings shed insight on how mitochondrial dysfunction may contribute to the pathogenesis of AD via decreased clearance of Aβ.
Mental Health Outcomes in a Sexually Abused, Counseling-Seeking Population
Emily Kulas, Susan Long
Department of Psychology, Lake Forest College
The Zacharias Sexual Abuse Center in Lake County serves survivors of sexual assault and sexual trauma. The center is interested in how their adult clients are faring throughout treatment. This study examines self-report mental health symptomology. The Trauma Symptom Inventory (TSI) is used to determine mental health outcomes approximately every three months. Data from the TSI was used in analyses to determine changes over time, and associations with demographic variables. Preliminary findings and suggestions are shared with the Zacharias Sexual Abuse Center in an attempt to improve treatment efficacy.
The importance of a balanced diet: The effect of protein-to-carbohydrate ratio on body and organ size in drosophila
Josephine Masandika1, Diego Rojas-Toledo1, Christen Kerry Mirth2, Alex Shingleton1
Protein and carbohydrate are essential for organismal growth and development. While the individual effects of protein and carbohydrate deprivation on final body size have been well studied, what is less well understood is how the relative amount of protein to carbohydrate in a diet affects growth. Here, we explore how the absolute amount and relative ratio of protein and carbohydrate interact with each other to affect final body size and body proportion, using Drosophila as a model organism. We reared flies on 24 different combinations of protein and carbohydrate (four different food levels, each with six different protein-to-carbohydrate ratios), and measured the body parts of the resulting adults. As expected, a decrease in total amount of nutrients in a diet results in a decrease in final body and organ size. However, our data indicate a strong interaction between the quantity of protein and carbohydrate on size, such that the effect of increasing carbohydrates depends on the quantity of proteins in a diet, and vice versa. Intriguingly, at low protein level an increase in carbohydrates actually decreases body and organ size. These data indicate that body size is not only influenced by the absolute amount of nutrients in a diet, but also how balanced the diet is.
Influence of part-set cuing and connectedness on spatial memory
Yuri Parasiuk, Jennifer Salgado-Benz, Matthew Kelley
Department of Psychology, Lake Forest College
The current study explored the influence of part-set cuing and connectedness on spatial memory. Cole et al. (2013) reported part-set cuing facilitation with snap circuits, but Watkins et al. (1984) showed no influence of part-set cuing on memory with chess pieces. One key methodological different is that snap circuits were interconnected and the chess pieces were not. Across two experiments, participants viewed boards with either connected or unconnected chess pieces (Exp 1) or snap circuits (Exp 2) and then were asked to reconstruct the boards with or without cues. Both experiments yielded similar patterns of results: part-set cuing facilitation occurred only when the pieces were connected and there was no influence of part-set cuing when the pieces were unconnected. This indicates that cuing depends, in part, on the formation of strong inter-item associations.
Parkinson’s Disease Insight from Yeast: New tools to uncover contributions of variant forms of the protein Alpha-Synuclein
Saul Bello Rojas, Logan Graham, Peyton Schrag, Shubhik DebBurman
Neuroscience Program and Biology Department, Lake Forest College
Parkinson’s disease (PD) is a hypokinetic neurodegenerative disorder characterized by the death of midbrain dopaminergic neurons. Misfolded proteins and aggregated α-synuclein leads to the accumulation of Lewy Bodies. While the full-length α-synuclein (which is 140 amino acids long) is the major Lewy body component, smaller versions of α-synuclein have recently been discovered, including splice variants (α-syn 126, α-syn 112, and α-syn 98; Beyer et al, 2008, McLean et al., 2011). The individual contributions of each such splice variant towards α-synuclein-based PD pathology is not clear. Along with spliced variants, the familial mutants (A30P, E46K, H50Q, G51D, and A53T) of these splice variants have not been studied. We hypothesized that these familial mutant splice variants likely contribute more to PD than the WT versions of the variants (α-syn 112, α-syn 126, and α-syn 98). In this study, we designed and created the 12 familial splice variants for yeast expression, attached each with and without a localization tag - green fluorescent protein (GFP). Here, we will describe the steps and data that led to creating the familial variants and transformation in yeast. This summer, we plan to evaluate their aggregation, localization, and toxicity properties, compared with the WT versions of α-synuclein.
Investigation of α-synuclein sumoylation in yeast as a protective mechanism against toxicity in Parkinson’s Disease
Alexandra Roman, Galina Lipkin, Shubhik DebBurman
Neuroscience Program and Biology Department, Lake Forest College
Parkinson’s disease (PD) is a hypokinetic neurodegenerative disorder that affects midbrain dopaminergic neurons and results in cell death. Within affected cells are insoluble aggregates known as Lewy bodies, whose main component is the misfolded form of a 140-amino-acid long protein, α-synuclein. This protein is highly modified with additional chemical attachments that are considered relevant to PD. One critical modification is the addition of a protein called SUMO (small ubiquitin-related modifier), which is thought to maintain α-synuclein solubility. Previous studies indicate that a majority of α-synuclein sumoylation takes place on lysine-96 and lysine-102. When these amino acids are blocked for sumoylation, α-synuclein was found less soluble and more toxic than wild-type form in dopaminergic cell cultures. More organismal support is now needed for sumoylation’s protective capacity against α-synuclein toxicity. The mechanism as to how sumoylation protects against toxicity is also not known. The goal of this project is to test the hypothesis that sumoylation protects against α-synuclein toxicity in free-living organisms and that the mechanism of protection intersects with other cellular processes and α-synuclein modifications known to be aberrant in PD. Thus far, we have created α-synuclein sumoylation-blocking mutants (K96R, K102R, and K96R/K102R), tagged with green fluorescent protein (GFP) at the C-terminus, and expressed them in two unicellular organismal models (S. cerevisiae and S. pombe). We have examined α-synuclein’s localization in yeast and found that, in support of our hypothesis, the blocking mutants reside less at the plasma membrane and cause the protein to aggregate more. Next, we will examine whether these mutants affect yeast survival and change the level of protein expression and accumulation. Furthermore, we will also plan to study the sumoylation properties of several other forms of α-synuclein that are linked to PD (familial PD mutants, newly discovered splice-variants and C-terminal truncation variants of the protein) to better dissect the mechanism by which this protection is conferred.
Using antisense oligonucleotides (ASO) as a therapy for Batten disease
Maria G. Ruiz, Cecilia Reyes, Michelle L. Hastings
Department of Cell Biology and Anatomy, Rosalind Franklin University of Medicine and Science, and Neuroscience Program and Biology Department, Lake Forest College
Juvenile neuronal ceroid lipofuscinoses (JNCL) or more commonly known as Batten disease, is an autosomal recessive lysosomal disorder that is caused by a mutation in the cln3 gene. Patients with Batten disease experience progressive loss of motor coordination along with vision loss. 85% of batten disease cases result from a 1.02 deletion of exons seven and eight. Furthermore, it is difficult to determine a successful therapy for Batten disease because the function of the cln3 protein remains unknown. However, by using antisense oligonucleotides (ASO) we can form a truncated version of the cln3 gene that may result in a therapy for Batten disease by putting the gene back into frame. We are testing ASO A, which skips exon 6 of thecln3 gene, and ASO B, which skip exon 9 of the cln3 gene. By using a cln3Δex7/8 mouse model, we are testing the effects of ASO A and B on the phenotype of the mice. We breed cln3Δex7/8 mice and at P1 or P2 we perform an intracerebroventricular injection of either ASO A, ASO B or a scramble. Once the mice are two months old, we test their motor coordination skills monthly by having the mice perform a rotarod test. At four months of age we test the mice’s learning abilities using Morris Water Maze (MWM). Our results show that heterozygous mice perform significantly better than mutant mice for both the Rotarod and MWM, which means that the rotarod test and MWM is an effective measure of motor coordination and learning abilities respectively. We are still in the process of breeding and testing more mice to effectively determine whether the ASO therapy is improving the cln3Δex7/8 mice’s phenotype. We are also working to optimize the ASO therapy.
PARKINSON’S DISEASE FRONTIERS: Evaluation of three new disease linked mutations of α-synuclein in yeast models
Maiwase Tembo, Charles Alvarado, Maribel Munoz, Shubhik DebBurman
Neuroscience Program and Biology Department, Lake Forest College
Parkinson’s disease (PD) is a hypokinetic neurodegenerative disorder linked to the death of dopaminergic neurons found in the midbrain. Familial PD is one of two forms of PD and it accounts for 10% of all cases and is the result of mutations in one of six genes so far identified. The best-studied gene among them is α-synuclein, with six known mutations, each linked with a key amino acid change on the protein that causes disease. Three first identified mutants (A30P, E46K, A53T) have been well studied by many. We have shown that each mutant affects α-synuclein’s properties in distinct patterns, thus indicating the importance of each building block (Sharma et al. 2006, Brandis et al. 2006, Fiske et al. 2011). What we do not know is how the three more recently discovered mutants (H50Q, G51D, A53E) create cellular toxicity. Our goal is to test the hypothesis that each of these newer mutants confers toxicity by intersecting with known cellular processes that are disrupted in PD. we have created and expressed these mutants in budding and fission yeast models we have previously developed in our lab and our now testing several pathology-related properties. We already have preliminary evidence that all three mutants are toxic to yeast and have altered localization properties: they differ with each other on their localization patterns and the level of toxicity they confer to yeast. To further assess impact of individual mutants, we will assess properties of various combinations of new and older PD mutants and assess them also in combination with C-terminal truncations in α-synuclein that are already known to increase toxicity.
Neuroscience University Interdepartmental Program, Department of Molecular Pharmacology and Biological Chemistry, Northwestern University
Stephanie Valtierra, Liming Li
Neuroscience University Interdepartmental Program, Department of Molecular Pharmacology and Biological Chemistry, Northwestern University
*Ms.Valtierra graduated from Lake Forest College in 2008 with a biology major. She is pursuing her PhD in Neuroscience at Northwestern University.
Prions are infectious proteins that can cause a group of neurodegenerative disorders known as transmissible spongiform encephalopathies or prion diseases. The prion concept is now extended to explain the etiology of a diverse group of mammalian misfolding diseases, such as Alzheimer’s disease, Parkinson disease, and amyotrophic lateral sclerosis. In each case, the pathogenesis is linked to a host protein with altered amyloid conformations that are transmissible through a prion-like mechanism. Currently, these protein misfolding diseases remain incurable and there is an urgent need for effective and safe therapeutic drugs in clinics. Interestingly, there are several amyloid prion elements identified in the budding yeast Saccharyomices cerevisiae (S.c.). [SWI+], the prion form of Swi1 in S.c., was identified in our laboratory. We have observed that [SWI+] abolishes the expression of Flo1, a cell surface glycoprotein required for filamentous growth and flocculation. Based on this finding, we established a [SWI+] reporter (FLO1promoter-URA3) that can faithfully report the prion status of Swi1 in a simple growth assay. We show that this yeast cell-based assay is suitable for high-throughput screening (HTS) for anti-prion compounds in a 384-well plate format. Several pilot screens were carried out and 84 hits have been obtained, many of which were verified by secondary assays. Our preliminary results demonstrate that this yeast-based HTS platform is efficient and cost-effective. We plan to perform large-scale screens to identify additional anti-prion compounds and explore their effectiveness in antagonizing other yeast and mammalian prions as well as their underlying anti-prion mechanisms. We hope our work will lead to the discovery of chemical probes for prion studies and provide valuable information to aid the development of therapeutic drugs for protein misfolding diseases.
Degree of dopamine lesion in the substantia nigra and ventral tegmental area reflects severity of akinetic behavior in a rodent model of Parkinson’s Disease
Johnathan Vinkavich, Kuei Y. Tseng
Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science, and Neuroscience Program, Lake Forest College
Parkinson’s Disease is a neurodegenerative disease associated with akinesias. These akinesias are driven by the loss of dopamine-producing neurons in the substantia nigra. Parkinson’s Disease patients do not show symptoms until 80% of these dopamine cells are lost. Similarly, previous studies in animal models show that dopamine depletion of at least 70% is necessary for motor deficits to begin and is accompanied by a 55% loss of dopamine neurons in the neighboring ventral tegmental area. How this loss of dopamine neurons in the ventral tegmental area plays into akinetic behavior remains unknown. The goal of this study is to determine if the loss of dopamine cells in the VTA is correlated with akinetic behaviors in a similar manner to that seen when substantia nigra dopamine cells are lost. Towards this goal we used a unilateral 6-hydroxydopamine rodent model. Akinetic behavior was measured via stepping performance tests and compared to cell loss as measured by a stereological technique. Initial results confirm a second order polynomial correlation between substantia nigra cell loss and decrease in stepping performance (R2=0.64).