Linked Life Data

11696604

Source:http://linkedlifedata.com/resource/pubmed/id/11696604

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2001-11-6
pubmed:abstractText
Lens fiber cell gap junctions contain alpha(3) (Cx46) and alpha(8) (Cx50) connexins. To examine the roles of the two different connexins in lens physiology, we have genetically engineered mice lacking either alpha(3) or alpha(8) connexin. Intracellular impedance studies of these lenses were used to measure junctional conductance and its sensitivity to intracellular pH. In Gong et al. 1998, we described results from alpha(3) connexin knockout lenses. Here, we present original data from alpha(8) connexin knockout lenses and a comparison with the previous results. The lens has two functionally distinct domains of fiber cell coupling. In wild-type mouse lenses, the outer shell of differentiating fibers (see 1, DF) has an average coupling conductance per area of cell-cell contact of approximately 1 S/cm(2), which falls to near zero when the cytoplasm is acidified. In the inner core of mature fibers (see 1, MF), the average coupling conductance is approximately 0.4 S/cm(2), and is insensitive to acidification of the cytoplasm. Both connexin isoforms appear to contribute about equally in the DF since the coupling conductance for either heterozygous knockout (+/-) was approximately 70% of normal and 30-40% of the normal for both -/- lenses. However, their contribution to the MF was different. About 50% of the normal coupling conductance was found in the MF of alpha(3) +/- lenses. In contrast, the coupling of MF in the alpha(8) +/- lenses was the same as normal. Moreover, no coupling was detected in the MF of alpha(3) -/- lenses. Together, these results suggest that alpha(3) connexin alone is responsible for coupling MF. The pH- sensitive gating of DF junctions was about the same in wild-type and alpha(3) connexin -/- lenses. However, in alpha(8) -/- lenses, the pure alpha(3) connexin junctions did not gate closed in the response to acidification. Since alpha(3) connexin contributes about half the coupling conductance in DF of wild-type lenses, and that conductance goes to zero when the cytoplasmic pH drops, it appears alpha(8) connexin regulates the gating of alpha(3) connexin. Both connexins are clearly important to lens physiology as lenses null for either connexin lose transparency. Gap junctions in the MF survive for the lifetime of the organism without protein turnover. It appears that alpha(3) connexin provides the long-term communication in MF. Gap junctions in DF may be physiologically regulated since they are capable of gating when the cytoplasm is acidified. It appears alpha(8) connexin is required for gating in DF.
pubmed:grant
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-10069981, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-10586946, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-11083898, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-11443230, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-1325220, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-1420894, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-1783895, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-3556449, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-8188753, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-8522422, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-8577756, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-9016299, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-9268595, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-9413992, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-9765054, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-9813099, http://linkedlifedata.com/resource/pubmed/commentcorrection/11696604-9860964
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0022-1295
pubmed:author
pubmed:issnType
Print
pubmed:volume
118
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
447-56
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Gap junctional coupling in lenses from alpha(8) connexin knockout mice.
pubmed:affiliation
Department of Physiology and Biophysics, State University of New York, Stony Brook, NY 11794-8661, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.