1991 |
Reed, Randall R |
R13Activity Code Description: To support recipient sponsored and directed international, national or regional meetings, conferences and workshops. |
Conference On 2nd Messengers/Protein Phosphorylation @ Gordon Research Conferences
The Gordon Conference on Second Messengers and Protein Phosphorylation in June 1991 will concentrate on the structure and function of proteins involved in signal transduction pathways, interaction between components of these cascades, and the mechanisms of modulation of their function. Considerable progress has been made in the identification of proteins involved in signal transduction. The current efforts in many laboratories is to examine the specificity of interactions among the components in the pathway. The design of the conference will bring out the multifaceted approaches currently being used to examine these questions. These approaches include the genetic analysis of pathways in simpler organisms, identification of the mutations in G proteins underlying human disease, and the biochemical studies of protein interactions. The Conference should provide a lively form for the exchange of information, ideas and prospects for future work. Last year approximately 80% of the participants in the conference presented data either in posters or as speakers. Such active participation by the conferees at all levels, including graduate students, postdoctoral fellows as well as junior and senior investigators, encourages discussion and fosters new interactions. The sessions planned for the 1991 Conference are: 1) Signalling Pathways in microorganisms focussing primarily on yeast and Dictyostelium discoideum 2) Role of small GTP binding proteins in regulation of cellular function 3) G protein structure and function 4) Mechanisms of sensory transduction in the visual and olfactory systems 5) Regulation of gene expression 6) Receptor/G protein Interactions 7) The structure and function of enzymes which generate second messengers 8) The mechanisms of bacterial chemotaxis 9) Genetic analyses and the elucidation of G protein function.
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0.903 |
1991 — 1993 |
Reed, Randall R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Role of Adenylyl Cyclase in Regulating Neural Function @ Johns Hopkins University
This project aims to elucidate the functional activities mediated by adenylyl cyclase with special emphasis on the regulation of enzyme activity by GTP binding proteins and other modulatory factors. The transduction of extracellular signals across the plasma membrane occurs in all eukaryotic and prokaryotic organisms. In many of these systems, extracellular ligands interact with integral membrane receptors to initiate the transmembrane signalling. On the intracellular side of the membrane, activated receptors catalyze the dissociation of GTP binding protein subunits which in turn activate intracellular effector proteins including adenylyl cyclase, cGMP phosphodiesterase, phospholipase C, and numerous ion channels. The adenylyl cyclase enzyme, responsible for the generation of cAMP, plays a central role in many signalling pathways. It is expressed at extremely high levels in the vertebrate brain and its activity is modulated by many neurotransmitters. Elucidation of the function of this important enzyme and its regulation by protein-protein interactions is fundamental to an understanding of cellular activity in the nervous system. Abnormal activity of adenylyl cyclase or proteins that modulate its function have profound effects on development and differentiation as well as in learning and memory. The adenylyl cyclase enzyme has been the subject of considerable biochemical study. The recent molecular cloning of one form of the enzyme from bovine brain suggests a complex integral membrane protein. Among the aims of this proposal are: (1) to use molecular cloning approaches to characterize the proteins which are responsible for adenylyl cyclase activity in mammalian brain. (2) study the expression of distinct forms of adenylyl cyclase in an organism that is amenable to genetic manipulation. This includes examination of available genetic mutants in the enzyme which lead to profound memory and learning defects. (3) develop and use a genetic selection system to identify the functional domains of the enzyme responsible for catalytic activity and interaction with modulatory proteins. The information gained from these studies should provide significant insight into the mechanism of regulation of intracellular second messengers and the effect of their modulation in normal and abnormal neural function.
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1994 — 1995 |
Reed, Randall R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Adenylyl Cyclase and Regulating Neural Function @ Johns Hopkins University
This project aims to elucidate the functional activities mediated by adenylyl cyclase with special emphasis on the regulation of enzyme activity by GTP binding proteins and other modulatory factors. The transduction of extracellular signals across the plasma membrane occurs in all eukaryotic and prokaryotic organisms. In many of these systems, extracellular ligands interact with integral membrane receptors to initiate the transmembrane signalling. On the intracellular side of the membrane, activated receptors catalyze the dissociation of GTP binding protein subunits which in turn activate intracellular effector proteins including adenylyl cyclase, cGMP phosphodiesterase, phospholipase C, and numerous ion channels. The adenylyl cyclase enzyme, responsible for the generation of cAMP, plays a central role in many signalling pathways. It is expressed at extremely high levels in the vertebrate brain and its activity is modulated by many neurotransmitters. Elucidation of the function of this important enzyme and its regulation by protein-protein interactions is fundamental to an understanding of cellular activity in the nervous system. Abnormal activity of adenylyl cyclase or proteins that modulate its function have profound effects on development and differentiation as well as in learning and memory. The adenylyl cyclase enzyme has been the subject of considerable biochemical study. The recent molecular cloning of one form of the enzyme from bovine brain suggests a complex integral membrane protein. Among the aims of this proposal are: (1) to use molecular cloning approaches to characterize the proteins which are responsible for adenylyl cyclase activity in mammalian brain. (2) study the expression of distinct forms of adenylyl cyclase in an organism that is amenable to genetic manipulation. This includes examination of available genetic mutants in the enzyme which lead to profound memory and learning defects. (3) develop and use a genetic selection system to identify the functional domains of the enzyme responsible for catalytic activity and interaction with modulatory proteins. The information gained from these studies should provide significant insight into the mechanism of regulation of intracellular second messengers and the effect of their modulation in normal and abnormal neural function.
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1 |
2000 — 2003 |
Reed, Randall R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Cyclic-Nucleotide Channels in Olfactory Development @ Johns Hopkins University
DESCRIPTION (Verbatim From the Applicant's Abstract): This project aims to elucidate the role of cyclic nucleotide-activated ion channels in neuronal connectivity and differentiation. We will use a mammalian model system amenable to genetic manipulation to study the fate of neuronal progenitors and mature olfactory sensory neurons with specific defects in second messenger signaling pathways. We will investigate the role of activity dependent processes in the proliferation of neuronal precursors, the initial projection of sensory neurons to their target and the stabilization of neuronal connections. Molecular biological, genetic, biochemical and electrophysiological methods will be utilized to understand the role of the OcNC-1 and OcNC-2 ion channel subunits in olfactory neuronal differentiation and establishment of projections to the olfactory bulb. The absence of synaptic input to olfactory neurons results in the OcNC-1 and OcNC-2 subunits providing a central mechanism for initiating activity-dependent processes in development and subsequent odor transduction. The OcNC-1 protein functions, at least in part, to convert cyclic nucleotide increases into calcium influx and initiate membrane depolarization. In parallel, we will test the hypothesis that a second olfactory neuronal cyclic nucleotide channel, OcNC-2, has a distinct role in mediating critical stages of neuronal differentiation. Specifically, the application will (1) Characterize the contributions of the OcNC-1 and OcNC-2 channel subunits to the normal development of the olfactory epithelium. We will test the hypothesis that olfactory cyclic nucleotide-activated channels contribute to the development of the olfactory system and the maturation of appropriate connections. (2) Examine the effects of competition between normal and OcNC-1 deficient neurons and the role of neuronal activity in cellular differentiation and the establishment and maintenance of connectivity. These studies will incorporate a unique system to generate mice possessing an olfactory epithelium comprised of a mosaic of wild type and OcNc-1-deficient sensory neurons. (3) Test the hypothesis that the OcNC-2 subunit contributes to the functional properties of the cyclic nucleotide-mediated transduction pathway in mature olfactory neurons. This application will utilize the special properties of the olfactory system to elucidate the contribution of activity dependent processes in the normal and abnormal development of neuronal cells.
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1 |
2000 — 2004 |
Reed, Randall R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Molecular and Functional Basis Odorant Recognition @ Johns Hopkins University
The mammalian olfactory system displays remarkable sensitivity and specificity in the detection of odorant molecules. G protein-coupled receptors present in the cilia of the olfactory neurons activate a transduction cascade leading to electrical activity and the propagation of sensory information to the brain. The discovery of a large family of olfactory receptor (OR) genes nearly a decade ago provided an explanation for the differential sensitivity of individual olfactory neurons. Moreover, the apparent expression of only a single receptor type in each cell suggests that the selectivity and specificity characteristic of each neuron reflects the functional properties of the underlying receptor protein. However, until recently it had not been possible to characterize OR function by expression in heterologous systems. Preliminary analysis of a few receptors indicates that they may display relatively narrow ligand specificity. The development of functional expression systems presents an important opportunity to define the molecular mechanism underlying odorant recognition. Interestingly, the threshold for detection of some odorants differs greatly among individuals in the population. These specific anosmias and hyposmias appear to have a genetic basis and may derive from unappreciated variations in the complement and functionality of individual receptors. We propose to define the molecular logic used by odorant receptors to bind and discriminate among structurally related ligands. These experiments will characterize the ligand specificity of a large number of mouse olfactory receptors and probe key residues in the ligand recognition pocket. The evolution and structural conservation of olfactory receptors make them uniquely amenable to a systematic dissection of molecular recognition. We will utilize molecular and functional approaches to elucidate the genetic and genomic variations that lead to specific anosmias. These experiments will complement those derived from in vitro analysis by providing information on receptor genes that are functionally important in the behavioral response of an animal. These experiments will afford new insights into the basis of odorant discrimination, information coding and the genetic basis of variation in sensory perception by the mammalian brain.
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2006 — 2007 |
Reed, Randall R |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Perireceptor Contributions to Chemical Communication @ Johns Hopkins University
[unreadable] DESCRIPTION (provided by applicant): The perception of sensory information plays a critical role in social and sexual behavior. Olfactory stimuli have been shown to elicit important responses such as intermale aggression, sexual arousal, puberty acceleration, and estrus synchronization. In many mammals, including humans, these communication stimuli have been identified as small hydrophobic, volatile molecules. These communication chemicals are present at high concentrations in biological fluids and activate specific sensory neurons by binding to specialized receptors of nasal neuroepithelia. Although there have been considerable advances in elucidating the nature of these receptors and the transduction pathway that leads to the propagation to the brain, we know very little about the critical process for managing these hydrophobic molecules in the hydrophilic nasal mucus. A specific class of lipocalins, Major Urinary Proteins (MUPs) 4 and 5 (nasal MUPs), are present in the mucus and have been shown to selectively bind a number of small hydrophobic odorants and pheromones in vitro. However, the in vivo function of the nasal MUPs as well as the other nasal lipocalins, remains unresolved largely due to the absence of molecular genetic tools. Several hypotheses have been postulated regarding their potential function including: 1. MUPs function as ligand-specific transporters delivering odorant and/or pheromones to receptor sites, 2. MUPs function as scavengers removing odorants from the receptor after transduction, 3. MUPs act as buffers preventing saturation of the receptors, and 4. MUPs act as transducers that activate the receptor. The overall hypothesis of this proposal is that nasal MUPs serve to selectively bind biologically meaningful hydrophobic molecules and are critical for odorant detection and subsequent behavior. The primary goal of this proposal is to apply integrated genetic, physiological and behavioral methods to elucidate the physiological role for nasal MUPs in mammalian chemical communication and the mechanisms whereby these compounds influence biologically relevant social behaviors. This approach to studying perireceptor events may open new avenues of research in the chemical senses and expand our understanding of normal and abnormal sensory function beyond the olfactory neuron. [unreadable] [unreadable] [unreadable]
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1 |
2007 — 2018 |
Reed, Randall R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Molecular Genesis and Organization of Olfactory Transduction Components and Cilia @ Johns Hopkins University
DESCRIPTION (provided by applicant): The mammalian olfactory system achieves remarkable sensitivity through novel genetic mechanisms, cellular specializations, and subsequent processing of sensory information by neuronal circuitry. The earliest steps in the transduction of odorant information into signals that are propagated to the brain occur in olfactory cilia. The dozen long immotile cilia of each olfactory neuron are the only part of the sensory cell exposed to the outside environment and the sources of odorant stimuli and their existence is essential for efficient odor detection. The olfactory neuron has developed efficient but poorly understood mechanisms for enriching the components of olfactory transduction (odorant receptor (OR), G protein (Golf), adenylyl cyclase (AC3) and olfactory cyclic nucleotide channel) in cilia. The abundant expression of the single polypeptide comprising the AC3 enzyme in all olfactory neurons makes it particularly amenable to elucidate the pathways and mechanisms responsible for cilia localization and enrichment. In this grant we will use molecular and genetic approaches to investigate the hypothesis that a specialized but broadly utilized mechanism and pathway is responsible for AC3 localization to cilia and that this localization is critical for cilia dynamics and function. In specific aim 1, we target the cilia localization signa of AC3 in vivo by a conditional genetic disruption approach and determine the consequences of re- localization of AC3 into different cellular compartments. In specific aim 2, we will utilize a robut expression system to identify components of the AC3 translocation/enrichment pathway leading to cilia localization and examine the dynamics of AC3 in cilia and role of AC3 localization in modulation of cilia length. Together, these experiments will expand our understanding of how an important class of proteins are enriched in cilia and the importance of their selective localizatio to this organelle. Cilia are present in essentially all terminally differentiated mammalian cells ad critical for the development of the organism. The pathways and mechanisms underlying adenylyl cyclase localization will have important consequences for olfaction, sensory communication and broadly for human health and understanding disease. The abundance of AC3 in olfactory neurons makes it particularly amenable for detailed studies. The AC3 enzyme is broadly expressed and highly enriched in many neuronal cilia of the brain and kidney where it likely mediates neuroendocrine/neurotransmitter signaling and its subcellular localization in these cells appear to be mediated by similar mechanisms. Modulation of this pathway should perturb complex behaviors and metabolic processes. Additionally, it is likely that the cilia localization pathway utilized by AC3 is shared by other proteins whose presence in cilia is critical for cellular function. Elucidation of these pathways will provide insight into cellular processes that have widespread consequences for human health.
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1 |
2007 — 2015 |
Reed, Randall R |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R56Activity Code Description: To provide limited interim research support based on the merit of a pending R01 application while applicant gathers additional data to revise a new or competing renewal application. This grant will underwrite highly meritorious applications that if given the opportunity to revise their application could meet IC recommended standards and would be missed opportunities if not funded. Interim funded ends when the applicant succeeds in obtaining an R01 or other competing award built on the R56 grant. These awards are not renewable. |
Molecular Mechanisms of Olfactory Receptor Choice @ Johns Hopkins University
[unreadable] DESCRIPTION (provided by applicant): The remarkable sensitivity and specificity of mammalian olfaction arises from the contributions at the molecular, cellular and tissue levels to establish a sensory organ. One of the most important components in this developmental process is the olfactory receptor (OR) protein. This large family of related GPCR coupled receptors is primarily responsible for defining the range of odorants that can be detected by an organism. The observation that each olfactory neuron expresses a single type of OR has important implications for information coding. Namely, the consequences of a ligand/OR interaction with a single receptor type can be directly translated into the physiological signal that the cell propagates to the olfactory bulb at the front of the brain. Additionally, the segregation of the axonal inputs into the olfactory bulb, organized according to the OR that each cell expresses, extends this relationship such that each discrete glomeruli represents an information unit reporting whether volatiles are present in the environment. Although extensive further processing of this initial signal by the olfactory bulb and higher brain areas is required to generate the complex perception and identification of odors associated with mammalian olfaction, the selective expression of exactly one OR in each mature olfactory neuron is critical for accurate information flow in this sensory system. In the absence of this highly regulated expression mechanism, the response profile of olfactory receptor neurons (ORNs) and the accurate organization of their projections to the olfactory bulb would be severely compromised. In spite of the critical importance of OR gene regulation, we know surprisingly little about the events associated with OR choice and regulation in olfactory function In this proposal, we will define the key steps utilized by olfactory receptor neurons to generate the selective expression of a single olfactory receptor protein type in each mature sensory neuron. These experiments will afford new insights into one of the most critical events in the establishment of a functional olfactory system and elucidate the role of specific regulatory proteins in this process. In addition, the regulation of the mammalian olfactory receptors provides a valuable paradigm for monoallelic gene expression that is critical for the proper expression of several genes that contribute to normal health and disease. [unreadable] [unreadable] [unreadable]
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