Manuel Covarrubias - US grants
Affiliations: | Thomas Jefferson University, Philadelphia, PA, United States |
Area:
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The funding information displayed below comes from the NIH Research Portfolio Online Reporting Tools and the NSF Award Database.The grant data on this page is limited to grants awarded in the United States and is thus partial. It can nonetheless be used to understand how funding patterns influence mentorship networks and vice-versa, which has deep implications on how research is done.
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High-probability grants
According to our matching algorithm, Manuel Covarrubias is the likely recipient of the following grants.Years | Recipients | Code | Title / Keywords | Matching score |
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1994 — 1998 | Covarrubias, Manuel L | R29Activity Code Description: Undocumented code - click on the grant title for more information. |
Molecular Regulation of Potassium Channels @ Thomas Jefferson University DESCRIPTION: (Adapted from applicant's abstract) The long-term objective of this proposal is to understand the molecular mechanisms that regulate the function of mammalian A-type K+ channels. These K+ channels activate and inactivate rapidly in response to membrane depolarization, and one of their main functions is to control the neuronal interspike interval in episodes of repetitive firing. Thus, A-type K+ channels directly influence neuronal signal coding that underlies such complex mental processes as learning, memory and other cognitive functions. Two distinct cloned A-type K+ channels will be investigated: mouse brain channels encoded by mKv4.1 and human brain channels encoded by hKv3.4. They activate at membrane potentials negative or positive to the neuronal firing threshold, respectively.The mechanisms that regulate the function of these K+ channels have not been explored. A combination of recombinant DNA methodology (e.g., heterologous expression and mutagenesis in vitro) and electrophysiology (voltage-clamp and patch-clamp recording) will be used to address three aspects: First, the biophysical properties of A-type K+ channels encoded by mKv4.1, at the macroscopic and single channel levels. This information will serve as the basis for understanding regulation of channel function. Second, the molecular mechanisms of regulation of mouse and human A-type K+ channels by protein kinase C (PKC). Specific questions to address here are: i) how activation of PKC controls gating of specific K+ channels; ii) mapping of the phosphorylation site(s) involved; and iii) the significance of PKC as regulator of distinct A-type K+ channels in the nervous system. Third, the mechanisms that may regulate gating of A-type K+ channels (mKv4.1) in their native environment. Specifically exploring: i) how single K+ channels are fine tuned by putative native factors; and ii) strategies that may reveal the structural channel domains involved. Studying the molecular mechanisms that regulate the function of A-type K+ channels may enhance our understanding of brain functions impaired in neurological and psychiatric disorders. |
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1997 — 1999 | Covarrubias, Manuel L | 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. |
Alcohol Action On a Cloned Potassium Channel @ Thomas Jefferson University APPLICANT'S ABSTRACT: The biological basis of ethanol intoxication and general anesthesia are believed to involve, in part, effects on ion channels that regulate nerve excitability. However, it is not known how ethanol and general anesthetics alter ion channel function at the molecular level and to what extent they share a common mechanism. The long-term goal of this proposal is to understand the molecular mechanism underlying inhibition of a cloned potassium channel by ethanol and other aliphatic alcohols (n-alcohols). Aliphatic alcohols behave as general anesthetics. The channel under study is encoded by Shaw2, a gene cloned from Drosophila. Previous studies in this laboratory have shown that Shaw2 potassium channels are selectively inhibited by clinically-relevant concentrations of ethanol in a manner consistent with a direct drug-channel interaction. Recombinant DNA technology, expression in frog oocytes or insect cells and patch-clamp recording will be used to address the following aspects: 1) The action of n-alcohols on the electrophysiological properties of Shaw2 potassium channels. 2)Identification of Shaw2 protein domains and amino acid residues that may interact with n-alcohols. 3)Overexpression, purification and reconstitution of recombinant Shaw2 potassium channels. The first two aspects will help us to understand the biophysical and molecular basis of channel inhibition. The third aspect will allow purification of sufficient quantities of the channel protein to permit the use of biochemical and biophysical methods to study more directly the interaction between n-alcohols and the channel. A comprehensive study of the molecular mechanism underlying inhibition of a potassium channel by n-alcohols is an important step towards understanding how ethanol can affect ion channel function in general, causing general anesthesia and other acute alterations affecting the brain and other organs. |
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1999 — 2001 | Covarrubias, Manuel L | 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 Properties of Subthreshold Potassium Channels @ Thomas Jefferson University DESCRIPTION: (Adapted from applicant's abstract) The long-term objective of this proposal is to understand the molecular mechanisms that regulate the function of mammalian A-type K+ channels. These K+ channels activate and inactivate rapidly in response to membrane depolarization, and one of their main functions is to control the neuronal interspike interval in episodes of repetitive firing. Thus, A-type K+ channels directly influence neuronal signal coding that underlies such complex mental processes as learning, memory and other cognitive functions. Two distinct cloned A-type K+ channels will be investigated: mouse brain channels encoded by mKv4.1 and human brain channels encoded by hKv3.4. They activate at membrane potentials negative or positive to the neuronal firing threshold, respectively.The mechanisms that regulate the function of these K+ channels have not been explored. A combination of recombinant DNA methodology (e.g., heterologous expression and mutagenesis in vitro) and electrophysiology (voltage-clamp and patch-clamp recording) will be used to address three aspects: First, the biophysical properties of A-type K+ channels encoded by mKv4.1, at the macroscopic and single channel levels. This information will serve as the basis for understanding regulation of channel function. Second, the molecular mechanisms of regulation of mouse and human A-type K+ channels by protein kinase C (PKC). Specific questions to address here are: i) how activation of PKC controls gating of specific K+ channels; ii) mapping of the phosphorylation site(s) involved; and iii) the significance of PKC as regulator of distinct A-type K+ channels in the nervous system. Third, the mechanisms that may regulate gating of A-type K+ channels (mKv4.1) in their native environment. Specifically exploring: i) how single K+ channels are fine tuned by putative native factors; and ii) strategies that may reveal the structural channel domains involved. Studying the molecular mechanisms that regulate the function of A-type K+ channels may enhance our understanding of brain functions impaired in neurological and psychiatric disorders. |
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2001 — 2011 | Covarrubias, Manuel L | 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. |
Mapping the Alcohol Site of a Neuronal Potassium Channel @ Thomas Jefferson University [unreadable] DESCRIPTION (provided by applicant): The long-term goal of this project is to determine the structural basis of the functional modulation of brain ion channels by alcohol. The subject of this study is the neuronal Shaw2 potassium channel, which is directly inhibited by pharmacologically relevant concentrations of ethanol and other short-chain members of the homologous series of 1-alkanols. Guided by previous results from this study, the central hypothesis of the project states that the activation gate of the Shaw2 channel contributes an amphipathic protein-protein interface that constitutes the alcohol binding site. This project focuses on investigating the activation gate as the locus of the interactions that control the alcohol-induced responses of the Shaw2 channel. The specific aims of the project are: 1) To investigate the specific structural determinants of alcohol binding in the S4-S5 loop of the Shaw2 potassium channel. 2) To investigate the structural features that govern the alcohol-induced responses of the Shaw2 potassium channel in the C-terminal section of the S6 segment. 3) To develop the prokaryotic KvAP channel as a model to explore the achitecture of the alcohol binding site in the Shaw2 potassium channel. The first two aims systematically combine recombinant DNA technology, electrophysiology and biophysical analyses to map the alcohol site in the Shaw2 channel. In light of the recently solved crystal structure of the KvAP channel, the last aim seeks the potential application of structural biology to determine the achitecture of an engineered alcohol site. A detailed map of the physiologically relevant amphipathic interfaces that bind alcohol in ion channels is the first step toward understanding acute alcohol intoxication at the atomic level and targeting these sites for therapeutic applications. [unreadable] [unreadable] [unreadable] |
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2003 — 2006 | Covarrubias, Manuel L | 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. |
Inactivation of Neuronal Kv4 Potassium Channels @ Thomas Jefferson University DESCRIPTION (provided by applicant): The long-term goal of this project is to understand the molecular mechanisms that control inactivation of neuronal Kv4 potassium channels. These potassium channels mediate the transient potassium current that is necessary for coding, integration and amplification of electrical signals in the nervous system. Kv4 channels probably utilize novel mechanisms of inactivation, which are distinct from those better known in Shaker potassium channels. Discoveries made during the last funding period are beginning to shed light on the physiological basis of Kv4 inactivation and how novel subunits shape this process. The specific aims for the next funding period are: (1) To probe conformational changes underlying a prominent pathway of inactivation in Kv4 channels; (2) To map the cytoplasmic moving regions controlling inactivation gating of Kv4 channels; (3) To investigate the molecular mechanisms underlying remodeling of Kv4 inactivation by Kv4-specific neuronal calcium sensors (KChlPs);(4) To investigate the molecular determinants of a KChIP domain with unique modulatory properties. Recombinant DNA technology, patch-clamp electrophysiology and thiol-specific reagents are applied to study inactivation of Kv4 channels expressed in heterologous expression systems (e.g., Xenopus oocytes or mammalian cells). Nuclear magnetic resonance (NMR) is applied to solve the structure of a putative inactivation domain in Kv4 channels. By investigating these aims, this project may gain insights into the molecular basis of brain functions that depend on the precise timing of electrical signaling, a domain where inactivation gating of Kv4 channels plays its most significant role. Specific areas that may benefit from this research include studies of associative learning and epilepsy. |
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2009 — 2010 | Covarrubias, Manuel L | 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. |
Gating of Neuronal Kv4 Channels @ Thomas Jefferson University The long~term goal of this project is to shed light on t molecular mechanisms that govern the function and regulation of the neuronal somatodendritic A~type assium current (I$A), Typically, ISA operates in the subthreshold range of membrane potentials and is a pivotal player in the ensemble of active membrane currents that regulate somatodendrilic signal integrati9n;therefore, it has a broad impact on the electrical plasticity of the brain. The Kv4 channel complex is th~ l moleculpr correlate of ISA. This complex includes the KV4 pore-forming a.~subunit encompassing three modulrr domains common to all voltage-gated K" channets: tetramerization (T1) domain, voltage-sensing domain a~ pore domain. In addition, Kv4 ((~subunits associate with at least two specific classes of auxiliary p~subunits ChiPs and DPPs). Although ground breaking S1udies of the OfO$ophila Shaker~B and bacterial potassium annels have helped explain fundamental properties (ionic selectivity, voltage-dependent gating and open-s te inactivation), many problems conceming relevant regulatory mechanisms remain unsolved. Given th cytoplasmic location of the T1 domain, its likely contribution to gating is one of the most intriguing Probl~ms . With NINDS suppon, previous studies from the PI's laboratory strongly support this contribution in Kv channels and its modulation by nitric oxide (NO). However, the molecular mechanisms have remained elu ive. To break new ground, this project will investigate the molecular mechanisms under1ying the contributions of the T1 domain to activation (Aim 1) and inactivation (Aim 2) in the Kv4 channel complex. The proposed actIvity will focus on putative moving parts that surround the interfacial Zn .... site, which is the targ~ of NO mod y l~lon;. and t~e exp~rimental approach is based ?n a multidiscIplinary research plan that combines electrop~StOloglcal , biochemical, molecular and computational methOdologies. This work is likely to impact the stud of neurological entities possibly linked to the Kv4 channel complex, such as epilepsy, pain plasticity, neur egenerative disorders, and autism. |
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2013 — 2014 | Covarrubias, Manuel L | 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.) |
Neuromodulation of Kv3.4 Channels in Nociceptors @ Thomas Jefferson University DESCRIPTION (provided by applicant): Persistent neuropathic pain affects millions of people worldwide and many cases remain refractory to available therapies. To treat neuropathic pain more effectively, it is necessary to understand the molecular basis of nociception and the maladaptive changes underlying the transition from acute to persistent pain. The down- regulation of A-type K+ currents in dorsal root ganglion (DRG) neurons has been implicated in the neuropathic pain state. However, it is not clear how this change contributes to disease because the specific roles and modulation of A-type K+ channels in nociceptors are not understood. The A-type high voltage-activated Kv3.4 channel is highly expressed in DRG nociceptors and is dramatically modulated by protein kinase-C (PKC) upon activating G-protein coupled receptors (GPCRs). Basically, phosphorylation of the Kv3.4 N-terminus converts the channel's fast-inactivating A-type phenotype into a non-inactivating delayed-rectifier-type phenotype. Furthermore, Kv3.4 channels accelerate the repolarization of the nociceptor action potential in a manner that depends on the phosphorylation status of the N-terminal inactivation gate. Kv3.4 channels might thus be instrumental in a novel mechanism of homeostatic plasticity involving second messenger signaling complex. We hypothesize that plastic changes occurring in nociceptors during the transition from acute to persistent pain compromise the ability of Kv3.4 channels to regulate the repolarization of the AP, which will impact critical downstream processes, such as Ca2+ signaling and synaptic transmission. To explore this hypothesis, we implemented a spinal cord injury (SCI) model of neuropathic pain and will pursue the following specific aims: 1) To investigate the neurophysiological mechanisms implicating Kv3.4 channels in nociception and neuropathic pain; and 2) To investigate the signaling mechanisms implicating PKC-dependent modulation of Kv3.4 channels in nociception and neuropathic pain. At various time points after the injury, and relative to appropriate controls, we will monitor pain behaviors and apply patch-clamp methods to investigate the activity and neurophysiological impact of Kv3.4 channels in DRG neurons. Also, we will combine immunological, molecular, and electrophysiological approaches to determine the phosphorylation status of Kv3.4 channels and the activity of PKC in membrane patches. To manipulate the expression of Kv3.4 channels in vivo, we will use viral vectors and siRNA to overexpress and knockdown. These experiments will break new ground by 1) shedding light on the contribution of peripheral mechanisms to neuropathic pain resulting from SCI; 2) elucidating the basis of operation of a novel mechanism of nociceptor homeostatic plasticity involving a Kv3.4 channel signaling microdomain that includes GPCRs, second messenger molecules and PKC; and 3) setting the stage to develop new and more effective therapeutic strategies that may help alleviate neuropathic pain. |
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2018 — 2021 | Covarrubias, Manuel L Dalva, Matthew B (co-PI) [⬀] Lepore, Angelo C [⬀] |
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. |
Exploring the Ephb2-Nmda Receptor Interaction in Spinal Cord Injury-Induced Neuropathic Pain @ Thomas Jefferson University Project Summary / Abstract: In a rodent model of cervical spinal cord injury (SCI), we propose to examine the contribution of altered EphB2 receptor-NMDA receptor (NMDAR) interaction to both excitatory synaptic neurotransmission in the superficial dorsal horn (DH) and persistent neuropathic pain (NP). The development of NP occurs in a significant portion of individuals affected by SCI, resulting in debilitating and often chronic physical and psychological burdens. Importantly, this pathological pain is particularly refractory to treatment, urgently calling for the identification of mechanistic targets that both robustly regulate pathological pain and avoid the devastating effects of opioid- based interventions. Hyperexcitability of DH circuitry (?central sensitization?) is a major substrate for NP after SCI. Studies have shown that NP is linked to EphB/ephrinB signaling through potentiation of NMDAR function, suggesting that the EphB-NMDAR interaction may be an important target for control of SCI-induced NP. We recently discovered that the EphB2-NMDAR interaction is regulated by a single extracellular amino acid of EphB2 (Y504). We demonstrated in vitro that EphB2-Y504 phosphorylation is required in spinal cord neurons for EphB-NMDAR interaction, NMDAR synaptic localization, and excitatory synapse function. We also found that transduction of DH neurons in vivo with EphB2 that constitutively interacts with the NMDAR results in long- lasting allodynia. We hypothesize that modulating the EphB2-NMDAR interaction in superficial dorsal horn (DH) neurons will impact synaptic localization and function of NMDARs, excitatory synaptic transmission between primary sensory afferents and DH neurons, and NP-related behaviors after cervical contusion SCI. Aim 1. Determine whether interaction with EphB2 drives NMDA receptors to synapses between primary nociceptive afferents and superficial DH neurons following cervical SCI. We will determine whether knocking down EphB2 in both uninjured and cervical contusion SCI mice using DH neuron subtype- specific expression of EphB2-shRNA reduces the localization of NMDAR subunits to excitatory synapses. Aim 2. Determine whether EphB2 regulates excitatory synaptic transmission in DH and NP-related behaviors after cervical SCI. We will determine whether DH neuron subtype-specific knockdown of EphB2 impacts: (2a) synaptic transmission between primary afferents and laminae I-II neurons using whole-cell patch clamp recording in an intact ex vivo preparation; and (2b) initiation and/or persistence of NP-related behaviors. Aim 3. Determine whether EphB2-Y504 phosphorylation regulates EphB2-NMDAR synaptic interaction in the DH and NP-related behaviors after cervical SCI. By expressing wild-type EphB2-Y504 or constitutively-phosphorylated (Y504E) or non-phosphorylatable (Y504F) mutants in a DH neuron subtype- specific manner, we will determine whether modulating EphB2-Y504 phosphorylation impacts: (3a) EphB2- NMDAR interaction, (3a) NMDAR levels at excitatory synapses, (3c) excitatory synaptic transmission between primary sensory afferents and DH neurons, and (3d) NP-related behaviors after cervical contusion SCI. |
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