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Ming Li

Bio: Ming Li is an academic researcher from University of South Alabama. The author has contributed to research in topics: Voltage-dependent calcium channel & Calcium. The author has an hindex of 23, co-authored 32 publications receiving 2604 citations. Previous affiliations of Ming Li include Tufts University & Howard Hughes Medical Institute.

Papers
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Journal ArticleDOI
10 Sep 1993-Science
TL;DR: The function of voltage-gated sodium channels that are responsible for action potential generation in mammalian brain neurons is modulated by phosphorylation by adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (cA-PK) and byprotein kinase C (PKC).
Abstract: The function of voltage-gated sodium channels that are responsible for action potential generation in mammalian brain neurons is modulated by phosphorylation by adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (cA-PK) and by protein kinase C (PKC). Reduction of peak sodium currents by cA-PK in intact cells required concurrent activation of PKC and was prevented by blocking phosphorylation of serine 1506, a site in the inactivation gate of the channel that is phosphorylated by PKC but not by cA-PK. Replacement of serine 1506 with negatively charged amino acids mimicked the effect of phosphorylation. Conversion of the consensus sequence surrounding serine 1506 to one more favorable for cA-PK enhanced modulation of sodium currents by cA-PK. Convergent modulation of sodium channels required phosphorylation of serine 1506 by PKC accompanied by phosphorylation of additional sites by cA-PK. This regulatory mechanism may serve to integrate neuronal signals mediated through these parallel signaling pathways.

267 citations

Journal ArticleDOI
TL;DR: A role for endogenously expressed Trp1 in regulating a Ca2-selective current activated upon Ca2+ store depletion is supported.
Abstract: SPECIFIC AIMTo determine whether host selenium (Se) deficiency can induce changes in the genome of a replicating influenza virus such that a normally mild virus converts into a more virulent strain and to characterize such genomic changes.PRINCIPAL FINDINGS1. Replication of a mild strain of influenza virus in Se-deficient mice results in a novel virulent strain that causes severe lung pathology even when passed into Se-adequate miceSe-deficient mice developed much more severe lung pathology postinfection with influenza virus than Se-adequate infected mice. To determine whether host factors or viral factors were responsible for the increased pathogenicity of influenza virus that had replicated in Se-deficient mice, a passage experiment was performed. We infected groups of Se-adequate and Se-deficient mice with influenza A/Bangkok/1/79 (H3N2). At 5 days postinfection, the mice were killed and virus was recovered from the lungs. Five separate isolates from each group of mice were used to inoculate five indiv...

262 citations

Journal ArticleDOI
01 Jun 1992-Neuron
TL;DR: Convergent modulation of brain Na+ channels by neurotransmitters acting through the cAMP and protein kinase C signaling pathways may result in associative regulation of electrical activity by different synaptic inputs.

237 citations

Journal ArticleDOI
TL;DR: Cultures of human tracheal epithelial cells transfected by calcium phosphate precipitation with a plasmid containing a replication-defective simian virus 40 (SV40) genome have been transformed and characterized to facilitate understanding of the mechanisms underlying pulmonary diseases.
Abstract: To facilitate understanding of the mechanisms underlying pulmonary diseases, including lung cancer and cystic fibrosis, we have transformed and characterized cultures of human tracheal epithelial cells. Cells were transfected by calcium phosphate precipitation with a plasmid containing a replication-defective simian virus 40 (SV40) genome. Colonies of cells with enhanced growth potential were isolated and analyzed for transformation- and epithelial-specific characteristics. Precrisis cells were observed to express the SV40 large tumor antigen, produce cytokeratins, have microvilli, and form tight junctions. After crisis, cells continued to express the SV40 large tumor antigen as well as epithelial-specific cytokeratins and to display the apical membrane microvilli. Apical membrane Cl channels were opened in postcrisis cells exposed to 50 microM forskolin. These channels showed electrical properties similar to those observed in primary cultures. The postcrisis cells have been in culture for greater than 250 generations and are potentially "immortal." In addition to providing a useful in vitro model for the study of ion transport by human airway epithelial cells, the cells can be used to examine stages of neoplastic progression.

222 citations

Journal ArticleDOI
TL;DR: A new model for metal ion homoeostasis in macrophages is proposed, where Nramps2 is a symporter of H+ and metal ions, Nramp1 is a highly pH-dependent antiporter that fluxes metal ions in either direction against a proton gradient.
Abstract: In mammals, natural-resistance-associated macrophage protein 1 (Nramp1) regulates macrophage activation and is associated with infectious and autoimmune diseases. Nramp2 is associated with anaemia. Both belong to a highly conserved eukaryote/prokaryote protein family. We used Xenopus oocytes to demonstrate that, like Nramp2, Nramp1 is a bivalent cation (Fe2+, Zn2+ and Mn2+) transporter. Strikingly, however, where Nramp2 is a symporter of H+ and metal ions, Nramp1 is a highly pH-dependent antiporter that fluxes metal ions in either direction against a proton gradient. At pH 9.0, oocytes injected with cRNA from wild-type murine Nramp1 with a glycine residue at position 169 (Nramp1(G169); P=3.22x10(-6)) and human NRAMP1 (P=3.87x10(-5)) showed significantly enhanced uptake of radiolabelled Zn2+ compared with water-injected controls. At pH 5.5, Nramp1(G169) (P=1.34x10(-13)) and NRAMP1 (P=1.09x10(-6)) oocytes showed significant efflux of Zn2+. Zn2+ transport was abolished when the proton gradient was dissipated using carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Using pre-acidified oocytes, currents of 130+/-57 nA were evoked by 100 microM Zn2+ at pH 7.5, and 139+/-47 nA by 100 microM Fe2+ at pH 7.0, in Nramp1(G169) oocytes; currents of 254+/-49 nA and 242+/-26 nA were evoked, respectively, in NRAMP1 oocytes. Steady-state currents evoked by increasing concentrations of Zn2+ were saturable, with apparent affinity constants of approx. 614 nM for Nramp1(G169) and approx. 562 nM for NRAMP1 oocytes, and a curvilinear voltage dependence of transporter activity (i.e. the data points approximate to a curve that approaches a linear asymptote). In the present study we propose a new model for metal ion homoeostasis in macrophages. Under normal physiological conditions, Nramp2, localized to early endosomal membranes, delivers extracellularly acquired bivalent cations into the cytosol. Nramp1, localized to late endosomal/lysosomal membranes, delivers bivalent cations from the cytosol into this acidic compartment where they may directly affect antimicrobial activity.

209 citations


Cited by
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Journal ArticleDOI
TL;DR: The key electrophysiological features of I(CRAC) and other store-operated Ca(2+) currents and how they are regulated are described, and recent advances that have shed insight into the molecular mechanisms involved in this ubiquitous and vital Ca( 2+) entry pathway are considered.
Abstract: In electrically nonexcitable cells, Ca2+ influx is essential for regulating a host of kinetically distinct processes involving exocytosis, enzyme control, gene regulation, cell growth and prolifera...

2,248 citations

Journal ArticleDOI
TL;DR: It is suggested that dysregulation of locus coeruleus-noradrenergic neurotransmission may contribute to cognitive and/or arousal dysfunction associated with a variety of psychiatric disorders, including attention-deficit hyperactivity disorder, sleep and arousal disorders, as well as certain affective Disorders, including post-traumatic stress disorder.

2,207 citations

Journal ArticleDOI
01 Apr 2000-Neuron
TL;DR: Together, these studies showed that the mechanisms of sodium channel function and regulation, purified sodium channel protein contained the essential and gives a perspective for future research on the ex-elements for ion conduction and voltage-dependent panding family of Sodium channel proteins.

2,022 citations

Journal ArticleDOI
TL;DR: It is shown that the full set of hydromagnetic equations admit five more integrals, besides the energy integral, if dissipative processes are absent, which made it possible to formulate a variational principle for the force-free magnetic fields.
Abstract: where A represents the magnetic vector potential, is an integral of the hydromagnetic equations. This -integral made it possible to formulate a variational principle for the force-free magnetic fields. The integral expresses the fact that motions cannot transform a given field in an entirely arbitrary different field, if the conductivity of the medium isconsidered infinite. In this paper we shall show that the full set of hydromagnetic equations admit five more integrals, besides the energy integral, if dissipative processes are absent. These integrals, as we shall presently verify, are I2 =fbHvdV, (2)

1,858 citations

Journal ArticleDOI
TL;DR: The goal of this review is to provide a comprehensive description of T-type currents, their distribution, regulation, pharmacology, and cloning.
Abstract: T-type Ca2+ channels were originally called low-voltage-activated (LVA) channels because they can be activated by small depolarizations of the plasma membrane. In many neurons Ca2+ influx through L...

1,620 citations