Division of Cardiology, Department of Medicine, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
* Author for correspondence (e-mail: david.gutstein{at}med.nyu.edu)
Accepted 6 November 2002
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Summary |
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Key words: Connexin43, Gap junction, Adherens junction, Desmosome, Cadherin, Desmoplakin
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Introduction |
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Adherens junctions, consisting of classical cadherins, link the
intercalated disc to the actin cytoskeleton. Desmosomes, in which desmoplakin
is a required component, attach to intermediate filaments
(Gallicano et al., 1998).
Knockout studies have revealed devastating consequences to heart development
and fetal viability in the absence of adherens junctions and desmosomes,
underscoring their importance to normal cardiac development and function
(Gallicano et al., 1998
;
Ruiz et al., 1996
). Adherens
junctions and desmosomes both associate with catenin family proteins, which
regulate cell-to-cell adhesion and the structure of the junctions at the
intercalated disc (Linask et al.,
1997
; Mathur et al.,
1994
; Ruiz et al.,
1996
; Sacco et al.,
1995
; Zhurinsky et al.,
2000a
; reviewed by Zhurinsky
et al., 2000b
). In addition, ß-catenin and p120 catenin are
thought to function directly in signaling pathways
(Anastasiadis et al., 2000
;
Daniel and Reynolds, 1999
;
Miller et al., 1999
;
Noren et al., 2000
). Recent
data have suggested that loss of Cx43 may be associated with alterations in
the intracellular localization of p120 catenin and, thus, may affect p120
catenin-dependent signaling pathways (Xu
et al., 2001
). Furthermore, forced expression of the gap junction
channel protein may influence ß-catenin-dependent signaling
(Ai et al., 2000
).
In this study, using conditional knockout (CKO) mice in which Cx43
expression in cardiomyocytes is virtually absent
(Gutstein et al., 2001a), we
investigated whether cardiac gap junctions may be responsible, at least in
part, for the structural integrity of the intercalated disc. We also examined
whether loss of cardiac gap junctions may lead to altered localization of the
catenins associated with the intercalated disc, which would suggest the
possibility of altered catenin-dependent signaling. Using a combination of
immunoblotting, immunofluorescence with confocal microscopy and electron
microscopy (EM) on CKO heart samples, we found that the adherens junctions and
desmosomes appear structurally intact in the absence of Cx43. The distribution
of other junction-associated proteins, such as the catenins, vinculin and
ZO-1, is also unchanged in the Cx43 CKO hearts. We conclude from these data
that Cx43 is not necessary for the organization of the cell adhesion junctions
and their associated catenins at the intercalated disc of the postnatal
cardiac myocyte.
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Materials and Methods |
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Antibodies
The Cx43 polyclonal antibody (custom manufactured by Research Genetics,
Huntsville, AL) was directed against the same epitope used by Yamamoto et al.
(Yamamoto et al., 1990). Other
polyclonal primaries included: anti-
-catenin (Santa Cruz Biotechnology,
Santa Cruz, CA); anti-desmoplakin (Serotec, Raleigh, NC); and
anti-pan-cadherin (Sigma). Monoclonal primary antibodies included: anti-Cx43
and -ZO-1 (Zymed Laboratories, San Francisco, CA); anti-N-cadherin,
-ß-catenin and -p120 catenin (BD Transduction Laboratories, Lexington,
KY); anti-pan-cadherin, -vinculin and -ß-tubulin (Sigma-Aldrich, St
Louis, MO); and anti-plakoglobin (Chemicon International, Temecula, CA).
Secondary antibodies included horseradish peroxidase (HRP)-conjugated goat anti-rabbit and anti-mouse IgG (Santa Cruz Biotechnology) for western blotting, and FITC- or Texas Red-conjugated goat anti-rabbit or anti-mouse antibodies (Jackson ImmunoResearch Laboratories, West Grove, PA) for immunofluorescence.
Immunoblotting and densitometry
For the evaluation of total ventricular protein levels by immunoblotting,
ventricular tissue was Dounce homogenized in the presence of Complete protease
inhibitor cocktail (Roche, Mannheim, Germany). Equivalent amounts of protein
per sample as determined by Bradford assay and confirmed with Coomassie
staining were electrophoresed on SDS-PAGE gels and transferred onto
nitrocellulose (Bio-Rad Laboratories, Hercules, CA). Blots were blocked
followed by incubation with appropriate primary and secondary HRP-conjugated
antibodies. Signal was detected with ECL chemiluminescent processing (Amersham
Pharmacia Biotech, Little Chalfont, UK) and autoradiography. At least two
separate experiments per protein were quantified by scanning the
autoradiograms on a Bio-Rad Gel Doc 1000 and calculating band intensity with
Quantity One software (Bio-Rad Laboratories).
Fraction preparation and immunoprecipitation
To determine cytosolic and plasma membrane catenin concentrations,
fractionation of samples was performed as described
(Atkinson, 1973). Briefly,
heart samples were Dounce homogenized, centrifuged at 500 g
for 10 minutes to remove insolubles and layered over a 45% sucrose cushion.
After centrifuging at 7000 g for 20 minutes, the supernatant
(cytosolic fraction) was separated from the cloudy layer immediately overlying
the sucrose (plasma membrane fraction). The resulting cytosolic and plasma
membrane fractions were analyzed by SDS-PAGE.
For immunoprecipitation, 150 µg of plasma membrane protein was incubated
with polyclonal anti-pan-cadherin antibody. After addition of protein
A-agarose-immobilized protein beads (Roche) to the samples, the protein A
suspension was centrifuged at 5000 g and supernatant was
removed. The protein A beads were washed in IP buffer and resuspended in
Laemmli buffer (Laemmli, 1970)
prior to incubation at 100°C and analysis by SDS-PAGE.
Immunofluorescence and confocal microscopy
For immunofluorescence, hearts were frozen in Tissue Tek OCT compound
(Sakura Finetek USA, Inc., Torrance, CA) upon sacrifice. Frozen sections (6
µm thick) were cut in an HM 560 cryostat (Microm, Walldorf, Germany) at
-20°C, placed onto Superfrost/Plus microscope slides (Fisher Scientific,
Pittsburgh, PA) and fixed in acetone. The sections were blocked in PBS with 5%
normal goat serum, 0.1% bovine serum albumin (BSA) and 0.1% sodium azide
(NaN3) at 37°C for 30 minutes and then incubated with primary
antibodies in PBS with 1% BSA and 0.1% NaN3 for 2 hours at
37°C. After washing in PBS, sections were incubated with secondary
antibodies in PBS with 0.1% BSA and 0.1% NaN3 at 37°C for 1
hour. Sections were washed again in PBS and mounted with Vectashield mounting
medium (Vector Laboratories, Berlingame, CA).
Immunostained sections were examined with a TCS-SP confocal laser scanning microscope (Leica, Heidelberg, Germany). Double-stained sections were visualized after ensuring that the settings were such that there was no cross-over of signal between the FITC and Texas Red channels. Experiments were conducted in a minimum of four control and CKO hearts simultaneously, at least in duplicate.
For the relative quantification of adherens junction and desmosomal
junction areas at the intercalated disc, images of intercalated discs in
short-axis were collected in series
(Gourdie et al., 1991;
Kaprielian et al., 1998
).
Stacked images of intercalated discs were traced with IPLab software
(Scanalytic, Fairfax, VA) for the calculation of area and mean fluorescence
(after correcting for background) of each intercalated disc. For presentation
only, stacked images of intercalated discs were deconvolved using Microtome
deconvolution software (VayTek, Fairfield, IA).
Electron microscopy
For EM, mice were anesthetized with pentobarbital prior to perfusion with
150 mM KCl and 5000 U/L heparin, followed by PBS. For morphology, hearts were
then perfusion fixed with 3% paraformaldehyde, 1% glutaraldehyde. The apical
segment was then removed and immersed in fresh fixative, post-fixed in 1%
OsO4, stained with 1% uranyl acetate, dehydrated and embedded in
Epon.
For immuno-EM, hearts were perfusion fixed with 3% paraformaldehyde in PBS. Apical segments were removed, washed in PBS and incubated in 0.05 M NH4Cl, 0.05 M PBS, followed by dehydration and embedding in Lowicryl K4M (Electron Microscopy Sciences, Fort Washington, PA). For the immunoreaction, incubation with primary antibody was followed by application of protein A conjugated to 10 nm gold particles. Sections were viewed on a Hitachi 7000 electron microscope.
Statistics
Data are expressed as mean±s.e. and comparisons between groups were
performed with a two-tailed t-test using Microsoft Excel software.
P<0.05 was considered statistically significant.
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Results |
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|
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Deficiency of Cx43 does not affect subcellular localization of
ß- or p120 catenin
Recent data have shown that the subcellular localization of p120 catenin is
altered in the Cx43 germline knockout mouse, suggesting that p120
catenin-dependent intracellular signaling may also be altered, possibly
accounting for some of the pathology associated with the loss of Cx43
(Xu et al., 2001). Since
cytosolic ß-catenin concentration mirrors its nuclear level
(Giarre et al., 1998
) and p120
catenin may complex with kaiso in the cytosol
(Daniel and Reynolds, 1999
),
cytosolic levels of these catenins probably reflect their availability to
influence signaling. In addition to their role in intracellular signaling,
p120 catenin and ß-catenin associate with cadherins at the plasma
membrane. We studied both the cytosolic and plasma membrane fractions from
four control and four CKO hearts. Levels of both ß-catenin and p120
catenin were unaltered in the cytosolic fraction
(Fig. 2A). Similarly, levels of
both ß-catenin and p120 catenin in neat plasma membrane fractions were
not significantly changed in the CKO hearts compared with controls
(Fig. 2B).
|
While p120 catenin concentration at the plasma membrane in the CKO hearts remained unchanged, we sought to determine whether p120 catenin remained associated with cadherin in the absence of Cx43 by using immunoprecipition. As demonstrated by immunoprecipitation of plasma membrane fractions with an anti-pan-cadherin antibody followed by blotting for p120 catenin, in the absence of Cx43 p120 catenin remained associated with cadherin at the plasma membrane (Fig. 2C).
Adherens junctions and desmosomes localize to the intercalated disc
in a similar pattern in both control and CKO hearts
In order to assess the localization of adherens and desmosomal junction
proteins at the intercalated disc in the absence of Cx43, we utilized
immunofluorescence with confocal microscopy. Sections from control and CKO
hearts double stained for Cx43 and cadherin showed that
adherens-junction-associated cadherin staining was primarily localized to the
intercalated discs in frozen sections from both control and CKO hearts
(Fig. 3). While Cx43 staining
was detected at the intercalated discs of control hearts, overlapping as well
as non-overlapping but juxtaposed areas of Cx43 and cadherin staining were
frequently seen (Fig. 3C), suggesting Cx43 and cadherin were closely associated at the intercalated disc.
Only rare Cx43 staining was seen in CKO hearts, as demonstrated in
Fig. 3E. Staining for the
presence of N-cadherin, the major cardiac cadherin subtype, in the control and
CKO hearts also showed no difference in localization (not shown).
|
In order to determine the localization of desmosomes in cardiac myocytes in the absence of Cx43, we double stained for Cx43 and desmoplakin, a necessary component of desmosomes (Fig. 4). As seen with adherens-junction-associated cadherin staining, gap junctions and desmosomes were often juxtaposed at the intercalated disc (Fig. 4E). However, despite their close proximity, double staining for desmoplakin and Cx43 revealed no changes in desmosomal localization in the absence of Cx43 compared with controls.
|
For the determination of relative localization of adherens junctions to desmosomes in the absence of gap junctions, we double stained for pan-cadherin and desmoplakin in control and CKO hearts and imaged with confocal microscopy in both the longitudinal and short-axis views. In order to minimize overlap, short-axis views of intercalated discs are presented in Fig. 5. In both control and CKO hearts, desmoplakin (green stain; A and D) and cadherin staining (red; B and E) had a similar distribution at the intercalated disc, although merged images (C and F) suggested that they are mainly juxtaposed (green and red stain in close proximity) rather than co-localized. We measured the area of the intercalated discs in control and CKO hearts stained with cadherin and desmoplakin. In hearts stained with cadherin, the intercalated disc area measured 93.8±10.7 µm2 in controls (n=6) versus 106±9.1 µm2 in the CKOs (n=5; P=0.42). Essentially identical values were obtained when the intercalated disc area was determined by visualizing desmoplakin expression (97.7±11.5 µm2 in controls versus 109±7.4 µm2 in CKOs; n=6 each; P=0.43).
|
Next, we used short-axis images to investigate whether adherens junctions and desmosomes were remodeled at the intercalated disc in the absence of gap junctions. Mean cadherin fluorescence in the CKO hearts was 87.7±12.8% of control values (n=7 controls and 8 CKO hearts; P=0.56), while desmoplakin fluorescence in the CKOs was 114±16.7% of control levels (n=7 control and CKO hearts; P=0.55). Thus, we found no significant differences in intercalated disc size or the abundance of adherens and desmosomal proteins at the intercalated disc in hearts devoid of Cx43 compared with littermate controls.
Catenins co-localize at the intercalated disc with associated
adhesion junctions in the presence and absence of Cx43
Given recent data suggesting altered p120 catenin intracellular
localization in the absence of Cx43 in cultured explanted embryonic neural
crest tissue (Xu et al.,
2001), we investigated whether p120 and other catenins may be
mis-localized in the CKO hearts. We double stained control and CKO heart
sections for cadherin and one of its associated catenins, p120. We found that
in both control and CKO hearts cadherin and p120 catenin staining colocalized
at the intercalated disc (Fig.
6). While staining for cadherin was most abundant at the
intercalated discs, p120 catenin was evident at the lateral borders of the
myocytes in addition to the intercalated discs in both groups.
|
Next, we examined the localization of ß-catenin and plakoglobin, catenins that associate with adherens junctions and desmosomes, respectively. Double staining for the presence of cadherin and ß-catenin showed that these proteins co-localized at the intercalated disc in both control and CKO hearts (Fig. 7A-F). Plakoglobin and desmoplakin were similarly co-localized at the intercalated discs of both control and CKO hearts (Fig. 7G-L). While staining of ß-catenin and plakoglobin was most intense at the intercalated disc, extensive cytoplasmic staining of both catenins was evident in control and CKO heart sections (ß-catenin: Fig. 7B, control and Fig. 7E, CKO; plakoglobin: Fig. 7H, control and Fig. 7K, CKO).
|
Localization of structural proteins ZO-1 and vinculin is unchanged in
CKO hearts
We evaluated structural proteins related to the intercalated disc
junctions, ZO-1 and vinculin, to determine their relative localization in the
absence of Cx43. The cytoskeletal protein ZO-1 complexes with Cx43 in cardiac
myocytes in a c-Src-mediated interaction and the association of ZO-1 and Cx43
is actually increased upon enzymatic disruption of intercellular contacts
(Barker et al., 2002;
Toyofuku et al., 2001
;
Toyofuku et al., 1998
). ZO-1,
which stained at the intercalated disc and along parts of the lateral cell
borders, was similar in distribution in control and CKO sections
(Fig. 8A,B). Vinculin, which
tethers the adherens junction complex to the actin cytoskeleton via
-catenin, is downregulated in a guinea pig model of pressure overload
hypertrophy (Wang and Gerdes,
1999
). The distribution of vinculin, which extended along the
entire sarcolemma in both controls and CKO myocytes, was not visibly different
in the absence of Cx43 (Fig.
8C,D).
|
Ultrastructure of CKO intercalated disc reveals absence of gap
junctions without alterations in adherens junction or desmosome
morphology
The morphology of the intercalated disc was evaluated in detail in the CKO
hearts and compared with controls using EM. The morphology of the intercalated
discs in the CKO hearts was no different than that of the controls, except for
the near-complete absence of gap junctions. Structures that appeared to be
adherens-type junctions and desmosomes in the CKO heart sections were
unchanged in their localization at the intercalated disc, organization and
general appearance when compared with the controls
(Fig. 9A,B).
|
In order to confirm the absence of Cx43 in the CKO hearts, we performed immuno-labeling of the sections for Cx43, followed by EM. As expected, in addition to the morphological absence of gap junctions in the CKO hearts, there was also a paucity of Cx43 labeling (Fig. 9C,D). Rare gap junctions were present in the CKO hearts and these junctions demonstrated Cx43 labeling, but did not label for Cx45. Similarly, no specific Cx45 labeling of gap junctions was observed in control hearts.
Immuno-labeling for cadherin, followed by EM, however, revealed no difference in localization of the adherens junctions in the CKO hearts. Indeed, structures with the typical appearance of adherens junctions at the intercalated disc labeled for cadherin in both the CKO samples and in controls (Fig. 9E,F). The specificity of cadherin labeling is demonstrated by the lack of cadherin label on the gap junction in Fig. 9E (black arrow) and the desmosomal junction in Fig. 9F (black arrowhead).
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Discussion |
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Studies of intercalated-disc-related protein expression in animal models of
heart disease have produced inconsistent results. For instance, cell adhesion
junction proteins are downregulated along with Cx43 expression in the
peri-infarct region of experimentally induced myocardial infarction
(Matsushita et al., 1999), but
are either upregulated or unchanged in genetic murine models of dilated
cardiomyopathy (Ehler et al.,
2001
).
Observational investigations of the dynamics of adhesion junction and gap
junction expression in cultured cells during postnatal mammalian heart
development and in regenerating hepatocytes have suggested that gap junctions
are not necessary for the establishment of the cell adhesion junctions at the
intercalated disc (Angst et al.,
1997; Fujimoto et al.,
1997
; Kostin et al.,
1999
). In addition, data from heterozygous Cx43-null mouse hearts
indicate that intercalated disc structure, including N-cadherin abundance and
distribution, was unchanged despite diminished (but not absent) Cx43
expression (Saffitz et al.,
2000
). Our studies presented here now provide the most direct data
that Cx43 is not required for the organization of the adhesion junctions and
their related proteins. Furthermore, we found no difference in cytosolic
levels of p120 catenin or ß-catenin in the CKO hearts by immunoblotting,
suggesting that the availability of either catenin for complexing
transcription factors and translocating to the nucleus was unchanged.
The CKO mouse provides an important model for the study of interactions between the gap junctions and the other junctions at the intercalated disc. The CKO mouse develops normally and has normal heart function by echocardiography, yet dies of sudden arrhythmic death starting at around two weeks of age. Thus, this model allows for the study of heart function and biochemical structure in the absence of Cx43, while avoiding the developmental abnormality and perinatal lethality of the Cx43 germline knockout. We chose to study one-month-old CKO mice because at the one-month point their survival curves have already started to diverge from littermate controls, yet sufficient numbers of mice could easily be generated for experimentation.
The results of this study have important potential implications for the
nascent field of cardiomyocyte transplantation. It appears that it may be
possible to introduce cultured cardiomyocytes into injured or infarcted
segments of the heart in order to improve global function
(Sakakibara et al., 2002).
However, mechanical coupling in the absence of effective electrical coupling
may negatively impact global ventricular function
(Gutstein et al., 2001b
). In
addition, islands of poorly coupled cells may serve as arrhythmogenic foci. In
this study, we have demonstrated normal cell adhesion junction distribution
and morphology in the absence of gap junctions. In this light, for optimal
effect, transplanted cardiomyocytes must be integrated electrically as well as
mechanically into the recipient heart.
In summary, despite the absence of gap junctions in the CKO hearts, adherens junction and desmosmal distribution and morphology at the intercalated disc remain intact. Furthermore, the localization of catenins associated with the intercalated disc junctions is unchanged, suggesting that decreases in Cx43 expression may not directly influence catenin-dependent signaling. In addition, structural proteins associated with the intercalated disc junctions ZO-1 and vinculin are also unchanged in their distribution despite the loss of Cx43. The results of this study suggest that the gap junction is not necessary for the organization of the cell adhesion junctions and associated proteins in the cardiac intercalated disc.
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Acknowledgments |
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References |
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![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Ai, Z., Fischer, A., Spray, D. C., Brown, A. M. and Fishman, G.
I. (2000). Wnt-1 regulation of connexin43 in cardiac
myocytes. J. Clin. Invest.
105,161
-171.
Anastasiadis, P. Z., Moon, S. Y., Thoreson, M. A., Mariner, D. J., Crawford, H. C., Zheng, Y. and Reynolds, A. B. (2000). Inhibition of RhoA by p120 catenin. Nat. Cell Biol. 2, 637-644.[CrossRef][Medline]
Angst, B. D., Khan, L. U., Severs, N. J., Whitely, K., Rothery,
S., Thompson, R. P., Magee, A. I. and Gourdie, R. G. (1997).
Dissociated spatial patterning of gap junctions and cell adhesion junctions
during postnatal differentiation of ventricular myocardium. Circ.
Res. 80,88
-94.
Atkinson, P. H. (1973). HeLa cell plasma membranes. Methods Cell Biol. 7, 157-188.[Medline]
Barker, R. J., Price, R. L. and Gourdie, R. G.
(2002). Increased association of ZO-1 with connexin43 during
remodeling of cardiac gap junctions. Circ. Res.
90,317
-324.
Daniel, J. M. and Reynolds, A. B. (1999). The
catenin p120(ctn) interacts with Kaiso, a novel BTB/POZ domain zinc finger
transcription factor. Mol. Cell. Biol.
19,3614
-3623.
Ehler, E., Horowits, R., Zuppinger, C., Price, R. L., Perriard,
E., Leu, M., Caroni, P., Sussman, M., Eppenberger, H. M. and Perriard, J.
C. (2001). Alterations at the intercalated disk associated
with the absence of muscle LIM protein. J. Cell Biol.
153,763
-772.
Fujimoto, K., Nagafuchi, A., Tsukita, S., Kuraoka, A., Ohokuma,
A. and Shibata, Y. (1997). Dynamics of connexins, E-cadherin
and alpha-catenin on cell membranes during gap junction formation.
J. Cell Sci. 110,311
-322.
Gallicano, G. I., Kouklis, P., Bauer, C., Yin, M., Vasioukhin,
V., Degenstein, L. and Fuchs, E. (1998). Desmoplakin is
required early in development for assembly of desmosomes and cytoskeletal
linkage. J. Cell Biol.
143,2009
-2022.
Giarre, M., Semenov, M. V. and Brown, A. M.
(1998). Wnt signaling stabilizes the dual-function protein
beta-catenin in diverse cell types. Ann. N. Y. Acad.
Sci. 857,43
-55.
Giepmans, B. N., Verlaan, I., Hengeveld, T., Janssen, H., Calafat, J., Falk, M. M. and Moolenaar, W. H. (2001). Gap junction protein connexin-43 interacts directly with microtubules. Curr. Biol. 11,1364 -1368.[CrossRef][Medline]
Gourdie, R. G., Green, C. R. and Severs, N. J. (1991). Gap junction distribution in adult mammalian myocardium revealed by an anti-peptide antibody and laser scanning confocal microscopy. J. Cell Sci. 99,41 -55.[Abstract]
Gutstein, D. E., Morley, G. E., Tamaddon, H., Vaidya, D.,
Schneider, M. D., Chen, J., Chien, K. R., Stuhlmann, H. and Fishman, G. I.
(2001a). Conduction slowing and sudden arrhythmic death in mice
with cardiac-restricted inactivation of connexin43. Circ.
Res. 88,333
-339.
Gutstein, D. E., Morley, G. E., Vaidyu, D., Liu, F., Chen, F.
L., Stuhlmann, H. and Fishman, G. I. (2001b). Heterogeneous
expression of gap junction channels in the heart leads to conduction defects
and ventricular dysfunction. Circulation
104,1194
-1199.
Kaprielian, R. R., Gunning, M., Dupont, E., Sheppard, M. N.,
Rothery, S. M., Underwood, R., Pennell, D. J., Fox, K., Pepper, J.,
Poole-Wilson, P. A. et al. (1998). Downregulation of
immunodetectable connexin43 and decreased gap junction size in the
pathogenesis of chronic hibernation in the human left ventricle.
Circulation 97,651
-660.
Kostin, S., Hein, S., Bauer, E. P. and Schaper, J.
(1999). Spatiotemporal development and distribution of
intercellular junctions in adult rat cardiomyocytes in culture.
Circ. Res. 85,154
-167.
Laemmli, U. K. (1970). Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227,680 -685.[Medline]
Linask, K. K., Knudsen, K. A. and Gui, Y. H. (1997). N-cadherincatenin interaction: necessary component of cardiac cell compartmentalization during early vertebrate heart development. Dev. Biol. 185,148 -164.[CrossRef][Medline]
Mathur, M., Goodwin, L. and Cowin, P. (1994).
Interactions of the cytoplasmic domain of the desmosomal cadherin Dsg1 with
plakoglobin. J. Biol. Chem.
269,14075
-14080.
Matsushita, T., Oyamada, M., Fujimoto, K., Yasuda, Y., Masuda,
S., Wada, Y., Oka, T. and Takamatsu, T. (1999). Remodeling of
cellcell and cellextracellular matrix interactions at the border
zone of rat myocardial infarcts. Circ. Res.
85,1046
-1055.
Miller, J. R., Hocking, A. M., Brown, J. D. and Moon, R. T. (1999). Mechanism and function of signal transduction by the Wnt/beta-catenin and Wnt/Ca2+ pathways. Oncogene 18,7860 -7872.[CrossRef][Medline]
Noren, N. K., Liu, B. P., Burridge, K. and Kreft, B.
(2000). p120 catenin regulates the actin cytoskeleton via Rho
family GTPases. J. Cell Biol.
150,567
-580.
Peters, N. S., Severs, N. J., Rothery, S. M., Lincoln, C., Yacoub, M. H. and Green, C. R. (1994). Spatiotemporal relation between gap junctions and fascia adherens junctions during postnatal development of human ventricular myocardium. Circulation 90,713 -725.[Abstract]
Ruiz, P., Brinkmann, V., Ledermann, B., Behrend, M., Grund, C., Thalhammer, C., Vogel, F., Birchmeier, C., Gunthert, U., Franke, W. W. et al. (1996). Targeted mutation of plakoglobin in mice reveals essential functions of desmosomes in the embryonic heart. J. Cell Biol. 135,215 -225.[Abstract]
Sacco, P. A., McGranahan, T. M., Wheelock, M. J. and Johnson, K.
R. (1995). Identification of plakoglobin domains required for
association with N-cadherin and alpha-catenin. J. Biol.
Chem. 270,20201
-20206.
Saffitz, J. E., Green, K. G., Kraft, W. J., Schechtman, K. B.
and Yamada, K. A. (2000). Effects of diminished expression of
connexin43 on gap junction number and size in ventricular myocardium.
Am. J. Physiol. Heart Circ. Physiol.
278,H1662
-H1670.
Sakakibara, Y., Tambara, K., Lu, F., Nishina, T., Sakaguchi, G., Nagaya, N., Nishimura, K., Li, R. K., Weisel, R. D. and Komeda, M. (2002). Combined procedure of surgical repair and cell transplantation for left ventricular aneurysm: an experimental study. Circulation 106,I193 -I197.[Medline]
Toyofuku, T., Yabuki, M., Otsu, K., Kuzuya, T., Hori, M. and
Tada, M. (1998). Direct association of the gap junction
protein connexin-43 with ZO-1 in cardiac myocytes. J. Biol.
Chem. 273,12725
-12731.
Toyofuku, T., Akamatsu, Y., Zhang, H., Kuzuya, T., Tada, M. and
Hori, M. (2001). c-Src regulates the interaction between
connexin-43 and ZO-1 in cardiac myocytes. J. Biol.
Chem. 276,1780
-1788.
Wang, X. and Gerdes, A. M. (1999). Chronic pressure overload cardiac hypertrophy and failure in guinea pigs: III. Intercalated disc remodeling. J. Mol. Cell. Cardiol. 31,333 -343.[CrossRef][Medline]
Xu, X., Li, W. E., Huang, G. Y., Meyer, R., Chen, T., Luo, Y.,
Thomas, M. P., Radice, G. L. and Lo, C. W. (2001). Modulation
of mouse neural crest cell motility by N-cadherin and connexin 43 gap
junctions. J. Cell Biol.
154,217
-230.
Yamamoto, T., Ochalski, A., Hertzberg, E. L. and Nagy, J. I. (1990). LM and EM immunolocalization of the gap junctional protein connexin 43 in rat brain. Brain Res. 508,313 -319.[CrossRef][Medline]
Zhuang, J., Yamada, K. A., Saffitz, J. E. and Kleber, A. G.
(2000). Pulsatile stretch remodels cell-to-cell communication in
cultured myocytes. Circ. Res.
87,316
-322.
Zhurinsky, J., Shtutman, M. and Ben-Ze'ev, A.
(2000a). Differential mechanisms of LEF/TCF family-dependent
transcriptional activation by beta-catenin and plakoglobin. Mol.
Cell. Biol. 20,4238
-4252.
Zhurinsky, J., Shtutman, M. and Ben-Ze'ev, A.
(2000b). Plakoglobin and beta-catenin: protein interactions,
regulation and biological roles. J. Cell Sci.
113,3127
-3139.