2003 — 2006 |
Ahern, Gerard P |
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. |
Calcium Signaling in Dendritic Cell Function
[unreadable] DESCRIPTION (provided by applicant): Dendritic cells (DC) are a heterogeneous population of rare leukocytes highly specialized for immune-surveillance, and the induction and regulation of primary immune responses. This unique capacity reflects their ability to continuously sample the microenvironment and ingest foreign and self-antigens. After encountering a "danger" stimulus in the form of microbes, inflammatory molecules or allergens, DC transform into potent stimulatory cells and migrate to secondary lymphoid tissues, where they trigger the activation of antigen-specific effector T cells. The signaling pathways that underlie these processes are undoubtedly complex, but intracellular calcium appears to play a crucial role. We have recently characterized two novel calcium signaling pathways in DC. First, we have identified the skeletal muscle-type ryanodine receptor (RyR1) in DC. RyR1 is a massive intracellular channel that can amplify small calcium transients within a cell to produce much larger, sustained calcium rises. Second, we have demonstrated that calcium fluxes trigger rapid secretion by DC. Such pathways enable DC to respond rapidly to external stimuli, and release autocrine and paracrine signaling factors including exosomes and leaderless secretory proteins. The goal of this proposal is to determine the RyRl-calcium regulated pathways in DC. We hypothesize that RyR1 integrates diverse cellular stimuli, and mediates the calcium pathways that drive DC function. An inter-disciplinary approach is outlined to investigate the properties of these calcium signaling mechanisms and understand how they participate in DC biology. We will accomplish the objectives of this proposal by pursuing the following specific aims: Aim 1 is designed to determine the role of RyR1 during DC development and function. Aim 2 tests the impact of endogenous and pharmacologic activators of RyR1 on DC. In Aim 3, we will elucidate the role of calcium-triggered secretion in DC. [unreadable] [unreadable]
|
1 |
2007 — 2010 |
Ahern, Gerard P |
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 Pain Mechanisms
[unreadable] DESCRIPTION (provided by applicant): We propose to study a novel mechanism by which sensory neurons detect noxious stimuli. The ability to detect noxious stimuli is critical to survival, but can also be the source of unwanted pain. Injurious chemical, thermal and mechanical stimuli are transduced by a variety of G-protein coupled receptors and ion channels expressed in nociceptive sensory neurons. The signaling pathways in these neurons are undoubtedly complex, but deciphering these pathways promises the potential for improved treatment of pain-the most frequently cited health-care concern. One newly identified mode of noxious signaling occurs via the electrostatic charge of cations. Extracellular cations and polyamines can directly sensitize and gate the capsaicin receptor TRPV1, an ion channel essential for the development of inflammatory hyperalgesia. An important question arising from this observation is whether basic peptides can similarly modulate the function of TRPV1 and thereby regulate sensory nerve excitability. Immune and epithelial cells secrete an array of highly charged, cationic proteins and peptides. Importantly, levels of these cations are markedly elevated in inflamed tissue, however despite this observation; their effects on sensory nerve function have barely been explored. We hypothesize that polycations and cationic peptides can regulate the excitability of nociceptors through the modulation of TRPV1. We will test this innovative hypothesis using a combination of robust electrophysiological and biochemical methodologies: In Aim 1 we will determine the activation and sensitization of TRPV1 by several inflammatory cationic peptides/proteins. In Aim 2 we will explore the ability of polyamines and cationic peptides to trigger neuropeptide secretion from peripheral and central terminals of sensory nerve preparations. In Aim 3 we plan to identify nociceptive behaviors and pathology arising from cationic regulation of TRPV1. [unreadable] [unreadable] [unreadable]
|
1 |
2011 — 2012 |
Ahern, Gerard P |
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.) |
Trpa1 and General Anesthetics
DESCRIPTION (provided by applicant): General anesthetics (GAs) are a diverse group of chemicals with the shared ability to induce reversible unconsciousness. Although these drugs have revolutionized surgery they are still less than ideal. In particular, many of these drugs provoke pain/irritation upon administration. Inhalant GAs can provoke airway irritation and sympathetic activation. Moreover, there is emerging evidence that noxious anesthetics have the potential to exacerbate post-surgical pain and inflammation. Approximately 200 million surgeries are performed worldwide each year, and therefore, understanding how GAs interacts with TRP channels is highly desirable. Our previous data show that desflurane/isoflurane excites sensory nerves by selectively activating the "mustard-oil" receptor (TRPA1). A major goal of this proposal is to elucidate amino acids in TRPA1 that are critical for anesthetic agonism. We hypothesize that desflurane binds to a cavity between the 5th and 6th transmembrane domains of TRPA1. We will explore 2 specific aims. (1) Using a genetic approach we will determine the putative sites on TRPA1 necessary for activation by desflurane. Our preliminary data reveal a critical role for transmembrane 5 of TRPA1 in anesthetic sensing, and thus we will focus on amino acids in this region. Further, we will model docking of desflurane to TRPA1 to validate our genetic/functional data and verify that desflurane directly interacts with TRPA1. (2) We will test the ability of desflurane analogs (including enantiomers) to activate TRPA1. These analogs are designed to probe the steric and electronic properties of the methoxy group in desflurane predicted to specifically interact with TRPA1. PUBLIC HEALTH RELEVANCE: Each year more than 200 million surgeries are performed worldwide under general anesthesia. Understanding the complete side effects of anesthetics is therefore an important objective. Many anesthetics are chemical irritants, provoking airways irritation and pain upon administration. In this proposal, we aim to identify the mechanisms by which these anesthetics activate pain receptors.
|
1 |
2013 |
Ahern, Gerard P |
U01Activity 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. |
Nociceptive Innervation and Receptors in the Bladder
DESCRIPTION (provided by applicant): Bladder pain syndromes are common and especially prevalent in women. One of the problems in treating bladder pain is that our fundamental knowledge of nociceptive signaling in the bladder is limited. For example, nociceptive innervation in the bladder and the precise localization of key nociceptive receptors are not well defined. Further, there is considerable controversy as to whether TRPV1, a major pain receptor, is expressed in the bladder urothelium. TRPA1, another important nociceptive channel, has been identified in bladder but not rigorously localized. Non-specific antibody labeling, and the preferential use of male rodents are major limitations of previous studies. The goal of this project is to exploit genetic mouse models to: 1) precisely map nociceptive nerve input to the male and female mouse bladder at different developmental stages, 2) unambiguously localize expression of key nociceptive channels, TRPV1 and TRPA1, to nerves and/or other tissues, and 3) confirm bone fide function of these channels in identified cells/tissu layers. At the conclusion we will be able to submit to GUDMAP the expression of the TRPV1 gene lineage, TRPV1 and TRPA1 in bladder relative to specific tissue anchor genes.
|
1 |
2021 |
Ahern, Gerard P |
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. |
Trpv1 and the Regulation of Arterial Tone
Small resistance arterioles are the principal regulators of tissue blood flow and blood pressure. These vessels sense changes in circumferential tension and continuously adjust their caliber to help maintain tissue perfusion, a process termed ?myogenic autoregulation?. Although, myogenic tone usually changes slowly in arterioles of the heart and skeletal muscle, the myogenic tone is very rapid. This speed allows these organs to regulate high flow rates (up to 85% of cardiac output) to maintain spatiotemporal perfusion. Further, in skeletal muscle, the arterial tone is quickly turned off (<1s) after an initial muscle contraction to allow increased blood flow (reactive hyperemia), and aid the transition from rest to exercise. Importantly, during heart disease, diabetes, sepsis and ageing, myogenic tone markedly declines, impairing hemodynamics, muscle performance and contributing to pathology. The underlying mechanisms that enable dynamic regulation of myogenic tone are unknown. In this proposal, we will explore a critical role for the heat-gated ion channel, TRPV1. Our preliminary data, using TRPV1 reporter mice and functional studies combined, show that TRPV1 channels specifically localize to the smooth muscle of arterioles in the heart, skeletal muscle and adipose. We hypothesize that TRPV1 serves as a transduction channel to confer dynamic myogenic tone in small arterioles. Specifically, we will test the proposal that TRPV1 integrates two distinct properties of blood flow, both mechanical stimuli downstream of mechanosensing GPCRs, and the local blood temperature. We propose 3 aims to test this innovative hypothesis and to understand the underlying mechanisms. (1) To test the hypothesis that TRPV1 is critical for dynamic myogenic tone in small arteries and mechanotransduction in arterial smooth muscle cells, (2) To test the hypothesis that PLC signaling and heat underlie TRPV1 myogenic tone, (3) To test the hypothesis that binding of PI(4,5)P2 enables persistent TRPV1 activation necessary for myogenic tone.
|
1 |