CARDIAC GAP JUNCTIONS--CONTROL OF EXPRESSION AND FUNCTIO

Project: Research project

Project Details

Description

Gap junction channels provide a mechanism for the regulated transport of
ions and small molecules from cell to cell. Alterations in gap junction
channel activity have been implicated in cardiovascular developmental
defects and disorders of cardiac impulse generation and propagation. Gap
junction channel proteins are encoded by the connexin multi-gene family,
consisting of at least twelve distinct members. Within this family of
genes, connexin43 is the most prominent in the cardiovascular system.
Connexin43 is post-translationally modified by phosphorylation, and recent
evidence of our own and of others has demonstrated that phosphorylation
profoundly affects the functional properties of the assembled gap junction
channel. Based upon our considerable progress in understanding
electrophysiological properties of rodent and human connexin43 channels,
the overall goal of this application is to gain mechanistic insight into
the relationship between connex43 phosphorylation and channel function.
Using a tightly focused combination of cellular electrophysiological and
molecular genetic approaches, the Specific Aims of this proposal are to:

1. Undertake detailed electro[physiological studies evaluating the effects
of phosphorylating and dephosphorylating agents on human and rodent
connexin43 in stably transfected mammalian cells.


2. Examine the role of specific phosphorylatable residues in modifying
channel function, through site-directed mutagenesis and structure-function
analysis.

3. Transiently express phosphorylation-site mutants in wild-type and
connexin43-null neonatal mouse cardiac myocytes and examine the
electrophysiological phenotype.

4. Target phosphorylation-site mutants to the hearts of wild-type and
connexin43-null mice, and evaluate the junctional channel properties in
dissociated cardiac myocytes.

We fully expect that this approach, where transfected cell lines are used
to identify gating properties and effects of phosphorylation-site
mutagenesis, and transiently transfected and transgenic myocytes are used
to study the impact of these mutations in the cardiac cell environment,
will provide new insight into both mechanisms and consequences of
connexin43 phosphorylation and channel function.
StatusFinished
Effective start/end date7/1/903/31/01

Funding

  • National Heart, Lung, and Blood Institute
  • National Heart, Lung, and Blood Institute

ASJC

  • Cardiology and Cardiovascular Medicine
  • Genetics
  • Cell Biology

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