Douglas C. Eaton - US grants

This proposal requests funds to purchase a VAX 11/750 computer and a 5205 Array processor. The system will be used by a small group of investigators to analyze data from 5 scientific projects. The 5 projects represent 4 areas of analytic work. (1) Analysis of single channel events. (2) Determination of the admittance and impedance of nerve cells. (3) Development of kinetic models to explain the results obtained in (1) and (2). (4) Performance of simple molecular dynamics calculations for model membrane systems. Each of these areas require substantial computational ability unavailable to the principal investigators.

In this project, we intend to investigate several questions about Na+ transport in the rabbit urinary bladder. These questions are: (1) What are the characteristics of the Na+ transport system in the basolateral or serosal facing membrane? We will describe the ATP dependence of the basolateral Na+ pump. We will also determine the stoichiometry of the pump and if the stoichiometry is variable. To perform these experiments, we will gain access to the basolateral membrane by permeabilizing the apical membrane with digitonin. Digitonin produces pores in the apical membrane which effectively removes the apical membrane as a permeability barrier to molecules as large as small proteins. (2) Can the dependence of the basolateral Na+ pump on ATP or ADP be an important control factor in regulating transepithelial Na+ transport; i.e., are the normal physiological concentrations of ATP or ADP in a range where the pump is running at less than maximal rate? (3) Are there other intracellular factors which might control the basolateral Na+ pump? In particular, can intracellular H+ ion control the basolateral Na+ transport? (4) Are there other transport mechanisms for moving electrolytes across the basolateral membrane? Specifically, is there Na-C1 co-transport or Na-HCO3 co-transport? (5) Does intracellular Ca++ or H+ control the amiloride-sensitive Na+ conductance of the apical membrane? We will examine this question in a simple model system, the A6 epithelial tissue culture line. The purpose of the above experiments is to define the cellular mechanisms by which Na+ transport is controlled and to develop a model of the transport in detail which has only previously been possible in much simpler tissues.

A symposium under the auspices of the Society of General Physiologists is planned for September 4-7, 1986, at the Marine Biological Laboratory in Woods Hole, Massachusetts. The general topic of the symposium will be: cell calcium and the control of membrane transport. Four broad areas will be covered: (i) regulation of intracellular free calcium including an examination of pathways for calcium influx into cells, mechanisms for efflux, and processes for sequestration or buffering of intracellular calcium: (ii) membrane receptor-mediated changes in intracellular calcium which occur by alteration of the balance among the pathways and processes discussed in section i; (iii) direct modulation by calcium of membrane transport processes including the direct effect of intracellular calcium in inhibiting or activating ionic channels and exchange systems; and (iv) modulation of intracellular processes by calcium including the interaction of calcium with protein kinases, cytoskeletal proteins and calmodulin as well as the role of calcium in the phosphorylations of membrane proteins. In addition, workshops will be held where the methodological aspects of selected techniques will be discussed in depth. 20 speakers have been invited, including 6 from overseas. This symposium will offer a unique opportunity to bring together physiologists, cellular biologists, and biochemists with their various research interests under one roof to allow cross-fertilization and critical comparisons to take place. The lecture program will be held during four morning sessions. The workshops will be held during the afternoons. In addition, afternoons and evenings will be devoted to contributed poster presentations related to the central themes of the symposium. A major keynote address is planned for one of the evenings. The published proceedings from this symposium are expected to make a timely and important contribution to this rapidly growing field.

The goals of this proposal are to examine mechanisms by which Na+ transport across renal tissue can be controlled or regulated at a cellular level. The two tissues which will be used for this work are cells from the cortical collecting tubule of rat and cells from the amphibian distal nephron line, A6. Both of these tissues display trans-epithelial sodium transport which can be induced by the hormone, aldosterone, and blocked by the diuretic, amiloride. The primary emphasis of this proposal will be an examination of apical Na+ channels using patch-voltage clamp methods. The rationale for the experiments is that the patch clamp method allows unambiguous identification and characterization of single transport proteins uncomplicated by interaction with other processes. Also, patch-clamp allows access to the inner surface of the cell membrane which is in general inaccessible in intact tissue. Such accessibility allows an examination of the role of intracellular factors in the normal function and control of the ion transport channels. The specific aims of the project are twofold. First, to characterize the channels which are present in the epithelial cell membranes in terms of their selectivity to various ions, their opening and closing kinetics and voltage dependence (if any). The second phase of the project will examine mechanisms by which Na+ transport may be physiologically regulated at a cellular level. In this phase, the possible regulatory roles of the physiologicical ions, Na+, Ca++, and H+, will be examined. Also the effect on single Na channels of the hormone regulators, aldosterone, ADH, and ANF will be investigated. Finally, the possibility that natural proteolytic agents, such as kallikrein, might contribute to the normal regulation of the channel will be investigated. The primary hypothesis which motivates the second phase of the proposal is that the majority of the increase in Na transport induced by aldosterone can be attributed to the conversion of non-functional Na channels which are present in the apical membrane prior to exposure to aldosterone into functional, high selectivity Na channels. ADH, on the other hand, produces its effects primarily by promoting the incorporation of new channel proteins in the membrane.

The goal of this project is to express, characterize and, possibly, isolate the membrane protein(s) which form the amiloride-blockade Na channel of tight epithelial tissue. The amiloride-blockable Na channel is a major component of normal regulation of total body Na homeostasis; it represents the primary locus for control of discretionary Na resorption in the kidney. The properties of this channel appear to underlie specific features of the pathophysiology of electrolyte and fluid imbalance. The amiloride-blockable Na channel is found only in tissues which are highly specialized for Na reabsorption and the channel does not appear to be related to the Na channels of excitable tissues. The molecular basis and mechanism for the regulation of this Na channel in any cell is poorly understood; therefore, the Xenopus oocyte, which lacks any amiloride-blockable conductance, will be used as an mRNA expression system which, when injected with exogenous mRNA from tissues which normally contain the Na channels, will readily allow detection of the characteristic electrophysiological signal from amiloride- blockable Na channels. In this fashion, regulation of the amiloride-blockable Na channel can be studied in a controlled, simplified environment. But, in addition, the injected oocyte can also serve as a sensitive bioassay for Na channel-encoding mRNA, and therefore can allow the isolation of the cognate cDNA through standard molecular biological techniques. Because of the simplicity of the oocyte system, a characterization of the regulatory mechanisms controlling the channel will be much simpler than in any of the tissues in which it is normally found. In addition, it will be possible to prepare a cDNA library from this active mRNA pool. This library can be screened, using the oocyte to allow an identification of clones in the library which are cognates of all mRNA species essential for Na channel production. This approach to the isolation of the Na channels gene(s) is an alternative to more traditional methods of protein isolation which have so far been used in an effort to isolate and characterize the Na channel. The immediate advantage of the oocyte expression system is that a every step of the characterization and isolation process, the assay involves a functional channel. Such an approach will allow the development of a detailed molecular anatomy of this important channel, and further extend understanding of its role in physiological and pathophysiological processes.

This project will use single channel patch clamp methods to examine the basic characteristics and the regulation of Na + and Cl- channels in epithelial tissue from normal and CF cells. The preparations which will be used are primary cultures derived from bronchial scrapings or nasal polyps and anepithelial call line ch expresses the CFTR protein (A6, originally derived from the distal nephron of Xenopus laevis). The rationale for the project is based on the observation that there are similar regulatory pathways for both amiloride-blockable sodium channels and outwardly-rectifying chloride channels in A6 cells. These results may have specific relevance to CF since the CF defect manifests itself as an abnormality in the regulation of both sodium and chloride channels. Therefore, the immediate goal of this application is to continue an examination of ion channel regulation using single channel methods in A6 cells and, in addition, extend our studies to an examination of similar channels in airway epithelial cells from cystic fibrosis patients. The specific aims of the proposal are (1) further examine the mechanisms for both sodium and chloride channel regulation in epithelial cells (including airway cells) placing particular emphasis on regulation which involves membrane-associated proteins and their metabolic products including guanine nucleotide-binding proteins and membrane-associated lipases and their metabolites (phospholipase A2 and arachidonic acid; phospholipase C and diacylglycerol); (2) regulation which involves phosphorylation/dephosphorylation by determining the effects of phorbol esters, diacyl glycerols, catalytic subunits of protein kinases, phosphatases and inhibitors of these agents. The important issue will be whether phosphorylation/dephosphorylation modulates any of the membrane-associated proteins associated with the CF defect which produce abnormal regulation of chloride and sodium channels; and (3) confirm the role of specific regulatory mechanisms in CF airway epithelial cells.

Hypertension is a major risk factor for stroke, heart disease and is a cause of chronic kidney disease. Several monogenetic disorders suggest that defects in epithelial sodium channels (ENaC) themselves or their regulation leads to hypertension. Therefore, understanding regulation of ENaC is important as a potential source of hypertension. The sodium flux through ENaC measured as current, INa, across the apical membrane is given as ????? = ???? where I is the current through one open channel, N is the channel density, and Po is the channel open probability. The amount of current can be altered by changing any of these parameters, but in general only N or Po change to alter transport. A lot of attention has been paid to changes in trafficking that change N, but, we feel that changes in Po are also a major mechanism for altering. We hypothesize that ENaC subunits are associated with specific domains of the apical membrane that contain ENaC signaling complexes. These domains have a membrane component which is rich in cholesterol and inositol lipid phosphates. They also have several membrane-associated proteins (MARCKS or MLP-1) that can modify ENaC activity by acting as PIP2- sequestering agents that present PIP2 to ENaC. All of these components are organized through cytoskeletal interactions. The inositol lipid phosphates within the domain anchor the signaling proteins (MARCKS or MLP-1) in the domain, but also interact with and increases the Po of individual ENaC channels. The association of ENaC with the domain, the inositol lipid phosphates, and the signaling complex also stabilizes the functional channels so they have relatively long half-lives. To test these hypotheses, we will: (1) examine binding of PIP2 to ENaC to determine if binding opens the channel or if the binding only promotes a state that has a higher probability of opening; (2) determine if ENaC is present in PIP2-rich lipid domains and determine if the presence of the PIP2- binding proteins, MARCKS or MLP-1, is necessary to maintain ENaC in these lipid domains; (3) examine the regulation of the pMARCKS/MLP-1 and how MARCKS/MLP-1 regulation;(4) examine the proteolytic regulation of MARCKS/MLP-1 by calpains and how the cleaved form of MLP-1 is stabilized; and (5) determine the effect of scaffolding proteins like MAL on the localization and stability of MARCKS and ENaC in the membrane. Determine if MAL is necessary for ENaC insertion into PIP2 rich domains of the apical membrane and, once ENaC is inserted, does MAL stabilize ENaC (and MARCKS) in the specialized domains.

In the U. S., cystic fibrosis is the most common lethal genetic disease in the caucasian population, affecting about 1 in 2500 live births. The genetic locus of the disease, CFTR, is an epithelial anion channel so it is not surprising that CF is characterized by abnormal chloride transport in affected epithelia. But individuals with cystic fibrosis not only have abnormal chloride transport but also have abnormal sodium transport. Certain epithelia, e.g. airway and the distal nephron, express both apical Na channels and CFTR. Activation of CFTR in these cells produces C1 reabsorption and hormones that stimulate CFTR also enhance Na reabsorption. Activation of both CFTR and epithelial Na channels (ENaC) may lead to dramatic increases in NaC1 entry into cells and associated cell swelling, so it is important that cells control NaC1 entry to avoid large changes in cell volume. We hypothesize that regulatory interactions between C1 channels and Na channels provide a mechanism by which epithelia can control net NaC1 entry across the apical membrane. Activation of CFTR is associated with an inhibition of ENaCs, providing a means by which epithelial cells can regulate net NaC1 entry. Preliminary results show that inhibition of ENaC activity is via a paracrine agent whose release is CFTR dependent. The first aim will examine how expression and activation of CFTR alters the activity of ENaC. This aim will determine if ATP released to the outside of cells in a CFTR-dependent manner can inhibit ENaC activity. This will be accomplished by inhibiting the extracellular action of ATP with ATP degrading enzymes; determining the rate of release of ATP from A6 monolayers; examining the coupling of purinergic receptors to ENaC inhibition; and determining if the ATP release is via CFTR-dependent exocytosis. Since modulation of net NaC1 reabsorption has important implications for cell volume regulation, we also hypothesize that ENaCs will regulate CFTR. Preliminary data show that forskolin/IBMX stimulated CFTR C1 currents are significantly increased in the presence of ENaC, suggesting that ENaCs regulate CFTR. The second aim will examine whether ENaC-mediated regulation of CFTR is via changes in the number CFTR channels at the plasma membrane and/or changes in open probability. These studies will provide new information about mechanisms of coordinate regulation of epithelial Na and C1 transport.

Denson
0091964


Small electrical signals are critical to normal brain function. The signals arise because of the movement of electrically charged particles called ions into and out of nerve cells (the most common ions are sodium, potassium, and chloride). Ion movement into and out of nerve cells is controlled by special proteins on the surface of nerve cells that act as switches and are called ion channels. We can measure the ion charges that move through one ion channel at a time using sensitive recording methods. One ion channel type switches on movement of potassium ions: a function that is important for rhythmic activity of repetitively firing nerve cells. Such cells control repetitive activities like breathing, heart rate, and wakefulness. This project will investigate two ways by which these potassium ion channel switches are turned on and off. First, some lipids activate the channels while some do not; we hope to find out why. Second, molecular biological methods have shown that potassium channel switches appear to vary slightly among different types of nerve cells, but the difference is enough to allow for the interaction of some potassium channels but not others with other cellular proteins that make turning on the ion channel switches easier. We hope to investigate the differences and the way that the extra proteins affect potassium channels.

This work is important for two reasons. First, this research will provide an understanding of how fats and other lipids could alter brain function. Second, this research will describe how some potassium channels are controlled and, therefore, provide an idea of how rhythmic activity in the brain (and its consequences) are regulated.

The long term goal of this program is to examine the control and regulation of ion transport in epithelial tissue. In particular this project will use single channel and biochemical methods to examine the regulation of amiloride-blockade sodium channels in renal and lung epithelial cells. These channels are interesting because of their relative uniqueness among channels in transporting tissue and because of the interesting hormonal regulation of these channels. However, the mechanisms for regulation of these channels have not been completely described. Therefore, this project will further investigate the signaling cascades which regulate sodium channels in three sodium-transporting epithelial cell lines using patch clamp techniques supplemented by direct biochemical measurements. The specific aims for the proposed grant period will investigate four signaling cascades that regulate sodium transport. The aims are (1) further examine the regulation of sodium channels by heterotrimeric G protein signaling cascades; specifically, what is the nature of the interaction between Galpha-3 and ENAC; do the G protein alpha subunits activate Na channels directly or do they activate some other effector molecule closely associated with the inner surface of the apical membrane; and do G protein betagamma subunits alter ENaC activity? (2) Examine the regulation of sodium channels by small G protein signaling cascades. The activation of one small G protein, K-Ras2A, is required to sustain normal ENaC activity. Elements of the K-Ras signaling cascade appear to be closely associated with the cytosolic surface of the apical membrane since the cascade can be activated in excised, inside-out patches. Therefore, the mechanism of activation of K-Ras and the signaling molecules activated by K-Ras will be examined. 3) Examine the regulation of sodium channels by inositol lipids and inositol lipid kinases. Sodium channels in excised, inside-out patches require the presence of phosphatidylinositol-4,5-bis-phosphate (4,5-PIP/2) and A6 cells have the necessary enzymes to produce 4,5- pip/2. (4) Investigate the mechanisms by which aldosterone increases sodium channel activity. Demonstrate that the signaling cascade that begins with aldosterone activation of K-Ras and leads to the PI-3K- mediated production of 3,4,5-PIP3 involves activation of phosphatidylinositol-dependent kinase (PDK1/2), serum glucocorticoid- dependent kinase (SGK), and the ubiquitin ligase, Nedd4. Determine that these signaling molecules are activated by activation of PI-3-kinase and that 4-PIP-5-kinase is activated to produce 4,5-PIOP2 and subsequently 3,4,5-PIP/3. Finally, we will use commercially available gene chips to identify new aldosterone-induced genes.

[unreadable] DESCRIPTION (provided by applicant): Salt and water transport by lung epithelial cells is critical for normal clearance of fluid from the lungs at birth and, in the post-natal lung, for maintaining a thin fluid layer on the surface of the airways to promote pulmonary gas exchange and mucociliary clearance of foreign particulates from the lung. Alveolar epithelial cells play a key role in this regulation of lung salt and fluid balance. This is achieved through vectorial transport of solutes between the alveolar surface and the interstitial spaces. Transport is by a two-step process involving movement of sodium from the lumen into the epithelial cell interior through sodium channels and subsequent active extrusion of sodium into the serosal space by the basolateral sodium pump. A significant portion of the net Na+ absorption can be inhibited by amiloride, and since molecular biological studies have confirmed the presence of amiloride-sensitive epithelial Na+ channels (ENaC) subunits, ?, ? and ? in lung epithelia, it is generally assumed that this portion of the Na+ transport is mediated by some form of ENaC. Functional epithelial sodium channels (ENaC) are formed by the assembly of some combination of the three subunits into a tetrameric structure. This process presumably occurs within the endoplasmic reticulum (ER) and is inefficient, as only a fraction of newly synthesized ENaC subunits assemble into channels that exit the ER and reach the plasma membrane. Preliminary experiments show that both cells transfected with ENaC subunits and native epithelial cells can express three distinct types of cation channels that are capable of transporting Na+. These highly selective, medium-selective, and non-selective cation channels appear to be composed of different combinations of ENaC subunits. Thus, unlike multimeric cation channels in excitable tissues, which are cotranslationally assembled, amiloride-sensitive cation channels appear to be post-translationally assembled and under the permissive conditions, some, but not all subunits can traffic to the plasma membrane. This raises the natural set of questions of how individual ENaC subunits are trafficked, where the subunits are assembled into functional ion channels, how they are inserted into the surface membrane, and how they are retrieved and degraded or recycled. In addition, a second set of questions is how these processes are regulated to produce the hormone-induced changes in the number and type of functional channels in the apical membrane. These questions form the basis for the hypotheses and specific aims of this project. How ENaC is assembled, inserted, and removed from alveolar call membranes will determine the capacity of the alveolar cells to transport Na; and, therefore has important implications for both lung physiology and pathology.

DESCRIPTION (provided by applicant): Salt and water transport by lung epithelial cells is critical for normal clearance of fluid in the developing and mature lungs. A delicate balance between alveolar fluid secretion and absorption results in a thin fluid layer on the surface of the airways that helps promote pulmonary gas exchange and mucociliary clearance of foreign particles from the lung. The alveolar epithelial barrier formed by lung epithelial cells and tight junctions between the cells play a key role in this process, and disruption of the barrier function can result in alveolar flooding. Chronic alcohol exposure appears to compromise the alveolar barrier. Nonetheless, compensatory increases in salt transport in the alcoholic lung appear to be sufficient to maintain approximately normal levels of airway surface fluid. However, alcoholic lungs when challenged by any significant stress (like major trauma or sepsis) are much more likely to develop edema implying that the salt and water transport mechanisms cannot respond to increased demand as nonalcoholic lungs can. It is hypothesized that alcohol-induced changes in epithelial barrier function and transport mechanisms predispose the lungs to acute edematous lung injury. While there is now substantial evidence that the maintenance of salt and water transport is a strongly regulated, energy-dependent process, the pathways for salt and water transport are not clearly defined in the normal lung, let alone how they are modified in the alcoholic lung. It does seem likely that some regulatory mechanism controlling the response of lung salt and water transport stress is abnormal in alcoholic lungs. It is hypothesized that abnormal glucocorticoid and TGF-beta responsiveness of lung epithelial cells prevents stress-induced increases in lung salt and water transport in alcoholic lungs.There are three specific aims of this proposal. The first aim is to determine if transport characteristics of the alcoholic lung are different from normal lung. The second aim is to determine how transport in stressed alcoholic lung differs from normal and alcoholic lung. The third aim to elucidate the cellular mechanisms responsible for alcohol-induced changes in lung transport. These experiments will improve our understanding of how chronic alcohol exposure alters alveolar fluid balance under normal and stressful conditions, and help in devising therapeutic strategies to prevent edematous lung injury.

molecular assembly /self assembly; sodium channel; protein transport; protein degradation; endoplasmic reticulum; endocytosis; vasopressins; kidney function; apical membrane; aldosterone; biological signal transduction; pathologic process; posttranslational modifications; protein structure function; amiloride; cell line; immunoprecipitation; transfection;

Secretion of transmitters, hormones, and other biologically active molecules depends upon a complex sequence of cellular events. Although some cells like nerve and muscle cells can communicate through electrical signals, most cells communicate through chemical agents that alter the activity of the cells from which they are released (known as autocrine agents), nearby cells (paracrine agents or transmitters), or cells in other parts of the organism (exocrine agents or hormones). Normal cellular function usually depends upon the very tight control of the amount and timing of the release of these agents. Many pathological events involve disruption of chemical communication between cells (most notably in the central nervous system, heart, lungs, and kidneys). Because of the importance of these chemical messengers, an enormous research effort has been directed to determining the properties of release from cells. However, because most of these methods are indirect or have low spatial or temporal resolution, there are still many unanswered questions concerning the release of such agents. The present program proposes an innovative, multidisciplinary approach to the investigation of cell communication processes at the molecular level. This proposal takes advantage of the combined expertise of two groups. The Center for Cell & Molecular Signaling (CCMS) will act to organize the biological expertise on the Emory campus while the Applied Sensors Laboratory (ASL) will act as the focal point on the Georgia Tech campus for development of the nanotechnology needed to study biological problems. CCMS and ASL already have established ongoing research programs and collaborative grants using nanotechnology to examine biologically active molecules in lung and renal cell systems. The interdisciplinary Program will focus on the application of integrated scanning nanoprobe sensing systems. Scanning probe microscopy techniques provide powerful means for obtaining chemical, topographical and optical information with high spatial resolution. Each technique -atomic force microscopy (AFM), scanning near field optical microscopy (SNOM) and scanning electrochemical microscopy (SECM) - is designed to provide a specific kind of biological data. SECM provides information on the activity of biological molecules at cell surfaces. Proof of concept experiments have already established the utility of such methods to measure paracrine agents like ATP and reactive oxygen species at cell surfaces with high temporal and spatial resolution, information required for in situ investigations of complex biological systems. This knowledge may lead to better understanding and new strategies for treatment of disorders specifically related to cell communication crocesses like diabetes, cystic fibrosis in the lung, and polycystic kidney disease.

Despite years of research on renal cell physiology in the normal kidney, a comprehensive understanding of the factors that govern total body homeostatic balance and associated disease states is still incomplete. However, it has become quite clear that normal homeostatic balance and the abnormal responses of the body to renal pathophysiology involves significant interaction among a variety of renal processes, systemic hormones, and responses of other tissues within the body. Although some of these interactions have been known for some time, the molecular mechanisms driving others such as apoptotic and proliferative responses have only recently been investigated. This is primarily because of new tools which are now available to study these interactions. There are cellular and molecular biological methods that make it possible to identify and modify the proteins that are responsible for maintaining normal homeostatic balance and those which are responsible for pathophysiological responses within the kidney and elsewhere in the body in response to loss of renal function. The Department of Physiology and the Division of Nephrology at Emory University have a long history of research into the identification, description and characterization of cellular processes in the kidney that are related to normal physiology and pathophysiology and how renal pathophysiology can impact other tissues in the body. The objective of this Program, Cellular and Molecular Biology of Renal Disease Processes, is to reinforce the existing interactions and develop new directions between a closely knit group of investigators who will use molecular and cellular biological tools to understand aberrations in renal cellular mechanisms that can lead to disease states and the impact of these disease states on other tissues. Project l is "ENaC Assembly, Trafficking, Degradation, and Recycling" which will characterize the apparently unique cellular processing of renal sodium channel proteins. Project 2, "The Role of Pendrin in Mineralocortieoid-Indueed Hypertension" will examine regulation of a pathway for chloride movement in the CCD. Project 3, "Insulin Signaling and Muscle Protein Turnover in Acidosis", examines the mechanisms of muscle wasting associated with renal disease. The last, Project 4, "Regulation of Urea Transporters in MDCK Cells", examines the regulation of renal urea transport proteins in a new model system.

DESCRIPTION (provided by applicant): The overall goal of our IRACDA program (Fellowships in Research and Science Teaching or FIRST) has been and continues to be the combination of a traditional mentored postdoctoral research experience at Emory or Morehouse School of Medicine, research-intensive institutions, with an opportunity for the fellows to develop teaching skills that involve instruction in teaching methods and a mentored teaching experience at one of the Atlanta University Center Schools (Spelman College, Clark Atlanta University or Morehouse College, all Minority Serving Institutions). Our combined program facilitates the progress of underrepresented minority postdoctoral candidates into research and teaching careers in academia and provides all program fellows with experience at Minority Serving Institutions (MSIs) that promotes the next generation of scientists at MSIs. Our program also strongly reinforces interaction among faculty at the Atlanta University Center (AUC) schools and their counterparts at the two research intensive institutions participating in this program. The objectives of our Program are four-fold: (1) to enhance research-oriented teaching at the AUC schools; (2) to increase or enhance the research backgrounds of developing scientists to conduct high quality research in an academic environment; (3) to further promote interaction between Emory University, the AUC schools, and Morehouse Medical School that will lead to further collaboration in research and teaching; and (4) to increase the number of well-qualified underrepresented minority students entering competitive careers in biomedical research. Evaluation of the Program shows that the fellows in the FIRST Program publish at the same rate as their peers supported on T32 grants at Emory and other institutions with IRACDA programs. The evaluation also shows that FIRST fellows enter academic positions and receive post-fellowship grant awards at the same rate as T32 fellows (based on NIH data). The program has benefited the MSIs by providing support for development and recruitment of new faculty, some of which are FIRST fellows, and providing new courses and training opportunities for MSI students. RELEVANCE (See instructions): Underrepresented minorities constitute a small fraction of the postdoctoral fellows in the life sciences and an even smaller fraction of principal investigators of NIH research grants. In addition, the number of underrepresented minority applicants for research grants and training positions is very low. The institutions of higher education in the Atlanta area have a unique opportunity to help address these problems and, at the same time, test a new model for post-doctoral training in which post-doctoral fellows have a traditional research-intensive experience, but also have an opportunity to engage in mentored teaching activities.

? DESCRIPTION (provided by applicant): The overall goal of our IRACDA program (Fellowships in Research and Science Teaching or FIRST) has been and continues to be the combination of a traditional mentored postdoctoral research experience at Emory or Morehouse School of Medicine, research-intensive institutions, with an opportunity for the fellows to develop teaching skills that involve instruction in teaching methods and a mentored teaching experience at one of the Atlanta University Center Schools (Spelman College, Clark Atlanta University or Morehouse College, all Minority Serving Institutions). Our combined program facilitates the progress of underrepresented minority postdoctoral candidates into research and teaching careers in academia and provides all program fellows with experience at Minority Serving Institutions (MSIs) that promotes the next generation of scientists at MSIs. Our program also strongly reinforces interaction among faculty at the Atlanta University Center (AUC) schools and their counterparts at the two research intensive institutions participating in this program. The objectives of our Program are four-fold: (1) to enhance research-oriented teaching at the AUC schools; (2) to increase or enhance the research backgrounds of developing scientists to conduct high quality research in an academic environment; (3) to further promote interaction between Emory University, the AUC schools, and Morehouse Medical School that will lead to further collaboration in research and teaching; and (4) to increase the number of well-qualified underrepresented minority students entering competitive careers in biomedical research. Evaluation of the Program shows that the fellows in the FIRST Program publish at the same rate as their peers supported on T32 grants at Emory and other institutions with IRACDA programs. The evaluation also shows that FIRST fellows enter academic positions and receive post-fellowship grant awards at the same rate as T32 fellows (based on NIH data). The program has benefited the MSIs by providing support for development and recruitment of new faculty some of which are FIRST fellows and providing new courses and training opportunities for MSI students.