Michael S. Grotewiel - US grants

The long-term objective of my laboratory is to understand the role of cell adhesion molecules in learning and memory, with an emphasis on integrins. Drosophila is an excellent model system for such investigations because of its powerful genetics and ability to perform well in many memory paradigms. Additionally, since the molecular events involved in learning and memory are well conserved from flies to mice, studies utilizing Drosophila will continue to provide highly relevant information regarding the fundamental molecular events underlying behavioral plasticity. Previously, a new Drosophila olfactory memory mutant called Volado was isolated. The Volado fly carries a mutation in a novel integrin alpha subunit gene. Integrins have not been widely studied for their role in learning and memory; however, they have been examined in a number of other processes. For example, integrins mediate cell-cell as well as cell-substrate adhesion, and have important roles in development, tumor metastasis and wound healing. While the signaling properties of integrins have also been explored extensively, only a small number of proteins that bind to the cytoplasmic regions of integrins have been identified. Thus, there is a large gap in our understanding of integrin-mediated processes underlying memory as well as integrin-mediated protein-protein interactions in general. One of the major goals during this funding period will be to identify the requisite integrin beta subunit that physically interacts with the Volado gene product. This will be accomplished by analyzing olfactory memory in animals harboring mutations in candidate beta subunit genes, determining whether the beta subunit is active in the adult or participates in developmental processes important for olfactory memory, and exploring genetic and biochemical links between Volado and its beta subunit. Another major goal will be to delineate the brain regions in which Volado and the beta subunit are active using targeted gene expression strategies in combination with behavioral analyses. Additionally, the role of proteins that directly bind to the cytoplasmic domains of Volado and its beta subunit will be explored via molecular and biochemical studies. Collectively, these studies will identify the integrin beta subunit that associates with the Volado gene product, determine where these two proteins must be expressed for normal memory to occur, and identify candidate proteins that function downstream of integrins in behavioral plasticity. Thus, the proposed studies will add greatly to our understanding of the molecular and cellular processes mediated by integrins within the context of learning and memory.

DESCRIPTION (provided by applicant): Dr. Michael Grotewiel was appointed as an assistant professor in the Department of Zoology in August, 1998. In his two years in this capacity he has demonstrated a strong commitment to excellence in research and teaching. This commitment is exemplified by the establishment of an extramurally funded research program and excellent ratings by undergraduate and graduate students in his courses and lectures. Additionally, Dr. Grotewiel has been an enthusiastic citizen in the Zoology Department and the Graduate Neuroscience Program by serving on a number of committees dealing with a variety of issues including graduate student admissions and recruiting, searches for faculty hires, liaison to the Dean, and laboratory space utilization. This Research Career Development Award (RCDA) would allow Dr. Grotewiel to substantially reduce his teaching and committee assignments, thereby tipping the balance of his efforts in favor of his research program. His primary immediate and long-term career goals are to focus on and expand his research program on the molecular bases of memory in Drosophila, ultimately raising it to a level of high national and international visibility. He also plans to continue teaching and some limited committee service, albeit at a reduced level such that it occupies less than 20 percent of his total effort. The long-term objective of his laboratory is to understand the molecular bases for memory in Drosophila. Drosophila is an excellent model system for such investigations because of its powerful genetics and ability to perform well in many memory paradigms. Additionally, since the molecular events involved in learning and memory seem to be conserved from flies to mice, studies utilizing Drosophila will continue to provide highly relevant information regarding the fundamental molecular events underlying behavioral plasticity. During this funding period, Dr. Grotewiel will continue his work on identifying molecules involved in integrin-mediated olfactory memory in Drosophila. One of the major goals will be to identify the requisite integrin beta subunit that physically interacts with alphaPS3, an alpha integrin previously shown to participate in olfactory memory. Another major goal will be to delineate the brain regions in which integrins are active using targeted gene expression strategies in combination with behavioral analyses. Additionally, the role of proteins that directly bind to the cytoplasmic domains of integrins will be explored via molecular and biochemical studies. Collectively, these studies will add greatly to our understanding of the molecular and cellular processes mediated by integrins within the context of learning and memory.

My laboratory is currently funded by NIMH and other sources to study the molecular bases of memory in Drosophila, but I have not previously received extramural support for studies on aging. Thus, I am an established investigator moving into aging research. Therapies aimed at ameliorating age-related functional declines would be greatly facilitated by a better understanding of the molecular bases of functional senescence. This project will explore the genetic relationship between control of longevity and functional senescence in Drosophila. Additionally, this project will use powerful genetic tools in Drosophila to explore the molecular underpinnings of functional senescence. Together, these studies will shed much light on age-related changes in nervous system function.

[unreadable] DESCRIPTION (provided by applicant): The long-term goal of this project is to understand the genetic pathways that influence functional senescence using the fruit fly, Drosophila melanogaster, as a model. Although a number of genes involved in life span determination have been identified, our understanding of genes that regulate age-related functional declines is limited. Thus, the processes that govern health span remain largely uncharacterized. During the proposed funding period, my laboratory will pursue the molecular mechanisms underlying altered functional senescence in a series of recently identified Drosophila mutants. We will also begin a systematic exploration of mechanistic connections between control of life span and control of health span. These studies will help us to understand the molecular processes that underlie functional senescence and potentially life span determination. These studies will help determine how we age. They should lead to information that will help us reduce the negative effects of aging in people. [unreadable] [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Aging is the deterioration of physical status that culminates in death. While much is known about genes and genetic pathways that impact life span in model organisms, to date little is understood about the molecular-genetic mechanisms that influence age-related functional declines or how these declines interact with regulation of life span. The studies in this project will use the fruit fly, Drosophila melanogaster, to investigate the genetic basis for locomotor senescence and life span regulation. Using a series of newly isolated mutants, we will assess the role of three genes in age-specific locomotor function and life span. Additionally, we will determine whether these genes function within known pathways that influence life span and/or locomotor senescence. This project will give us important new insights into the genetic basis for aging. PUBLIC HEALTH RELEVANCE: As people age they develop a number of health problems that include reduced ability to move and increased risk of dying. The studies in this project will help physicians identify and treat patients at risk for age-related health problems.

One of the major challenges in ethanol research is to identify conserved genetic mechanisms that influence the effects of ethanol on behavior. Integrated molecular studies in mice and humans in conjunction with preliminary genetic analyses in my lab indicate that the Drosophila model is well suited for identifying conserved genes underlying ethanol behavior. In this pilot project we will expand on our preliminary work by exploiting the Drosophila model to evaluate several candidate loci for their impact on locomotor behavior in the presence of ethanol. All of the candidate genes we will investigate are good orthologues of mouse and human genes based on primary amino acid sequence and presence of conserved protein domains. In Aim 1 we will assess the role of multiple candidate genes in ethanol sensitivity. In Aim 2, we will determine whether these candidate genes influence ethanol tolerance. In both Aims, we will explore additional candidate genes that work in concert with loci that influence ethanol sensitivity or tolerance. The planned pilot project is a key step forward in using the Drosophila model to identify conserved genetic mechanisms underlying ethanol behavior.

DESCRIPTION (provided by applicant): Alcohol-related disorders impose a substantial burden on society with far-reaching health consequences. The identification of novel genes and genetic pathways that influence alcohol-related behaviors will facilitate the development of new therapeutic interventions for alcoholism and other forms of alcohol abuse. In this project we will investigate genes and genetic pathways that have novel influences on ethanol behavior. Molecular-genetic information from this project should ultimately lead to better diagnosis, risk determination and treatment of alcohol-related disorders in humans. This project focuses on Clic4/Clic as a novel mouse/Drosophila gene that affects behavioral responses to ethanol. Preliminary studies indicate that this gene influences ethanol-related behavior in both fruit flies (Drosophila) and mice, suggesting that it has a conserved role in ethanol action. To further characterize Clic4/Clic and its associated molecular mechanisms in ethanol behavior, we have developed a coordinated study in Drosophila and mice. Using the Drosophila model, this project will identify the tissue site of Clic action (Aim 1), define the temporal requirements for Clic (Ai 2) and delineate molecular-genetic mechanisms of Clic function (Aim 3). Using the mouse model, this project will further characterize ethanol regulation of Clic4 in the brain (Aim 4A), characterize the role of mammalian Clic4 in drinking and other ethanol behaviors (Aim 4B), characterize downstream molecular responses to altered Clic4 expression (Aim 4C), and investigate the role of a focused set of molecular partners implicated in Clic4 action (Aim 4D). This project draws on the complementary expertise of two independent laboratories directed by PIs Grotewiel (fly) and Miles (mouse) and is designed to have several major points of integration. Clic4/Clic was originally implicated as a candidate gene for ethanol behavior by a series of analyses by the Miles laboratory on gene expression, linkage and association data. Subsequent genetic analysis of Clic in the fly by the Grotewiel laboratory made Clic4 a high priority locus for ethanol behavioral studies in the mouse (described as preliminary data). These studies come together to rationally support a more extensive investigation of how Clic/Clic4 influences ethanol responses in flies (Aims 1 and 2) and mice (Aims 4A and 4B). Furthermore, additional studies on ethanol-responsive genes in the mouse (Aims 4A and 4C) are now informing the design of experiments in flies that will investigate mechanisms of Clic action (Aim 3). The results of the Drosophila studies in Aim 3 will in turn guide the design of experiments in mice on mechanisms for Clic4 in mammalian ethanol behavior (Aim 4D). The deliberate cross-species integration in this project, implemented within a collaborative framework between the Miles and Grotewiel laboratories, will drive a vigorous genetic investigation of conserved mechanisms underlying ethanol behavior.

Project Summary/Abstract: Over the past 100+ years, studies in Drosophila melanogaster (Drosophila or flies) have contributed enormously to our understanding of the genetic basis for sex-determination, development, behavior, aging, disease and many other normal as well as pathophysiological processes. More recently, the fly model has also been used to explore the contribution of environmental factors in health and disease. Key among the environmental factors being investigated is diet. Altering the diet of flies has profound effects on their physiology, progression of disease markers and aging. For example, dietary restriction in flies (via reduced concentrations of nutrients) extends lifespan as found in other species. Changes in the fly diet also greatly impact egg-laying (an indicator of resource utilization) and can lead to the development of a type II diabetes-like state. Furthermore, our preliminary studies indicate that diet has a pronounced effect on ethanol sedation behavior in flies. Given the effects of diet in flies, the ongoing global obesity epidemic and the increasing incidence of obesity-related diseases, studies in flies hold tremendous promise for continuing to uncover key mechanisms underlying diet-related phenomena that could ultimately translate into improved prevention and treatment of a multitude of diet-related diseases in humans. We have consequently begun developing dye-based methods (Con-Ex) for measuring food consumption in flies. The overarching goals of the studies in this application are to (i) use our previously established dye-based Con-Ex feeding method with the dye Blue-1 as a food tracer to assess intake of diets that alter longevity?and importantly do so across the lifespans of flies and (ii) extend the utility of the method by identifying and validating dyes in addition to Blue-1 for use in Con-Ex studies. The proposed studies will address an important question related to the effects of diet on longevity and will lay the foundation for more sophisticated dietary consumption analyses in flies.

Project Summary ? Project 2 Alcohol use disorder (AUD) imposes a substantial burden on society with far-reaching health consequences. The identification of novel genes and genetic pathways that influence alcohol-related behaviors will facilitate the development of new therapeutic interventions for AUD. In this project my laboratory will use the Drosophila (fruit fly) model to investigate genes and genetic pathways that have novel influences on ethanol-related behavior. Molecular-genetic information from this project should ultimately lead to better diagnosis, risk determination and treatment of AUD in humans. A major focus for this project will be to explore the role of the MADS-box transcription factor Mef2 family in ethanol-related behavior. Our preliminary studies implicate a MEF2 family member in the subjective response to ethanol (SRE) in humans and also show that the sole fly ortholog Mef2 is required for normal ethanol sedation. Our data suggest that altered ethanol sedation in humans might underlie changes in SRE and that changes in both sedation and SRE might be driven by genetic variance in MEF2 genes. Our results also support the hypothesis that a deeper understanding of the Mef2 family of genes could lead to important insights regarding behavioral responses to ethanol, SRE and potentially AUD. Another major focus of this project will be to continue using the fly as an experimental platform for investigating the role of other candidate genes in ethanol behavior prioritized by our Bioinformatics and Analysis Core and/or implicated by studies in other Center Projects. Given our success with studies on Clic, the ryanodine receptor and Mef2, we will further invest in this cross-species approach for exploring conserved genes and pathways underlying ethanol-related behaviors in flies and multiple aspects of alcohol abuse in humans.

The Virginia-North Carolina Louis Stokes Alliance for Minority Participation (LSAMP VA-NC Alliance) Bridge to the Doctorate (BD) activity will offer 12 talented students from multiple LSAMP alliances the opportunity to pursue doctoral degrees in STEM fields at Virginia Commonwealth University. The overall goal of the program is to broaden participation in STEM graduate programs by addressing known barriers to URM participation in STEM graduate-level education, including lack of academic and social integration within STEM graduate programs, lack of STEM-related professional mentoring, and support for research self-efficacy. The project will implement a comprehensive program that includes rigorous academic preparation, mentoring activities and training, research training experiences, and professional development activities for the BD Fellows. The objectives for achieving the program goals include a multi-tiered recruitment strategy, development of an orbital model of support for BD Fellows, activities such that 90% of the Fellows complete the doctorate within 6 years of initial enrollment, and evaluation contributing to understanding the impacts, strengths, and weaknesses of the program for advancing knowledge.

The project will contribute to advancing the NSF’s Mission “To promote the progress of science: “to advance the national health, prosperity and welfare, or to secure the national defense” and its 2018-2022 Strategic Plan to: “foster the growth of a more capable and diverse research workforce and advance the scientific and innovation skills of the nation.” This project will increase the number of Ph.D.-level scientists by having BD Fellows discover, and subsequently conduct, state-of-the art research. Fellows will work alongside esteemed STEM faculty in a diversity of STEM disciplines, leading to a doctoral degree, and, ultimately, careers in research and teaching, thus contributing to our nation’s STEM enterprise. As the recruitment pool of LSAMP baccalaureate recipients includes a high proportion of individuals from underrepresented minority populations, the project anticipates that BD Fellows will be students from these groups. Therefore, the project will contribute significantly to broadening participation in academe and science research. Project success will aid in the recruitment and retention of future STEM scholars, long after the project has ended.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.