Linked Life Data

11934703

Source:http://linkedlifedata.com/resource/pubmed/id/11934703

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2002-4-5
pubmed:abstractText
We predict that the type 2 ryanodine receptor isoform (RyR-2) located in the osteoclastic membrane functions as a Ca(2+) influx channel and as a divalent cation (Ca(2+)) sensor. Cytosolic Ca(2+) measurements revealed Ca(2+) influx in osteoclasts at depolarized membrane potentials. The cytosolic Ca(2+) change was, as expected, not seen in Ca(2+)-free medium and was blocked by the RyR modulator ryanodine. In contrast, at basal membrane potentials (approximately 25 mV) ryanodine triggered extracellular Ca(2+) influx that was blocked by Ni(2+). In parallel, single-channel recordings obtained from inside-out excised patches revealed a divalent cation-selective approximately 60-pS conductance in symmetric solutions of Ba-aspartate [Ba-Asp; reversal potential (E(rev)) approximately 0 mV]. In the presence of a Ba(2+) gradient, i.e., with Ba-Asp in the pipette and Na-Asp in the bath, channel conductance increased to approximately 120 pS and E(rev) shifted to 21 mV. The conductance was tentatively classified as a RyR-gated Ca(2+) channel as it displayed characteristic metastable states and was sensitive to ruthenium red and a specific anti-RyR antibody, Ab(34). To demonstrate that extracellular Ca(2+) sensing occurred at the osteoclastic surface rather than intracellularly, we performed protease protection assays using pronase. Preincubation with pronase resulted in markedly attenuated cytosolic Ca(2+) signals triggered by either Ni(2+) (5 mM) or Cd(2+) (50 microM). Finally, intracellular application of antiserum Ab(34) potently inhibited divalent cation sensing. Together, these results strongly suggest the existence of 1) a membrane-resident Ca(2+) influx channel sensitive to RyR modulators; 2) an extracellular, as opposed to intracellular, divalent cation activation site; and 3) a cytosolic CaM-binding regulatory site for RyR. It is likely therefore that the surface RyR-2 not only gates Ca(2+) influx but also functions as a sensor for extracellular divalent cations.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
1931-857X
pubmed:author
pubmed:issnType
Print
pubmed:volume
282
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
F921-32
pubmed:dateRevised
2011-4-28
pubmed:meshHeading
pubmed-meshheading:11934703-Animals, pubmed-meshheading:11934703-Animals, Newborn, pubmed-meshheading:11934703-Binding Sites, pubmed-meshheading:11934703-Calcium, pubmed-meshheading:11934703-Calcium Channels, pubmed-meshheading:11934703-Calmodulin, pubmed-meshheading:11934703-Cations, Divalent, pubmed-meshheading:11934703-Cell Membrane, pubmed-meshheading:11934703-Cytosol, pubmed-meshheading:11934703-Egtazic Acid, pubmed-meshheading:11934703-Electric Conductivity, pubmed-meshheading:11934703-Electrophysiology, pubmed-meshheading:11934703-Fura-2, pubmed-meshheading:11934703-Ion Channel Gating, pubmed-meshheading:11934703-Membrane Potentials, pubmed-meshheading:11934703-Nickel, pubmed-meshheading:11934703-Osteoclasts, pubmed-meshheading:11934703-Potassium, pubmed-meshheading:11934703-Rabbits, pubmed-meshheading:11934703-Rats, pubmed-meshheading:11934703-Rats, Wistar, pubmed-meshheading:11934703-Ryanodine Receptor Calcium Release Channel, pubmed-meshheading:11934703-Valinomycin
pubmed:year
2002
pubmed:articleTitle
Ca(2+) influx through the osteoclastic plasma membrane ryanodine receptor.
pubmed:affiliation
Mount Sinai Bone Program, Department of Medicine, Mount Sinai School of Medicine, Bronx Veterans Affairs Medical Center, New York 10029, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.