Wanda Coombs - Academia.edu (original) (raw)

Papers by Wanda Coombs

Research paper thumbnail of Connexin43 Remodeling Caused by Inhibition of Plakophilin-2 Expression in Cardiac Cells

Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc.... more Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc. Here, we asked whether the presence of plakophilin (PKP)2, a component of the desmosome, is essential for the proper function and distribution of the gap junction protein connexin (Cx)43. We used RNA silencing technology to decrease the expression of PKP2 in cardiac cells (ventricular myocytes, as well as epicardium-derived cells) obtained from neonatal rat hearts. We evaluated the content, distribution, and function of Cx43 gap junctions. Our results show that loss of PKP2 expression led to a decrease in total Cx43 content, a significant redistribution of Cx43 to the intracellular space, and a decrease in dye coupling between cells. Separate experiments showed that Cx43 and PKP2 can coexist in the same macromolecular complex. Our results support the notion of a molecular crosstalk between desmosomal and gap junction proteins. The results are discussed in the context of arrhythmogenic right ventricular cardiomyopathy, an inherited disease involving mutations in desmosomal proteins, including PKP2. (Circ Res. 2007;101:703-711.)

Research paper thumbnail of Peptide Gap Junction Modulators

Research paper thumbnail of Abstract 1911: eNOS is a Binding Partner for the Gap Junction Protein Cx37 in Endothelial Cells

Circulation, Oct 28, 2008

Research paper thumbnail of Severity of autoimmune myocarditis is influenced by Connexin43 expression

The Journal of Immunology, May 1, 2012

Research paper thumbnail of Abstract 18393: Plakophilin-2, Ankyrin-G and Connexin43 Mutually Interact to Regulate Intercellular Coupling and Sodium Channel Function. Implications to Arrhythmogenic Cardiomyopathies?

Circulation, Nov 23, 2010

Research paper thumbnail of Humanized mice and _in vivo_ bioluminescence imaging: tools for testing antiviral drugs for varicella-zoster virus

Background / Purpose: Varicella-zoster virus (VZV) causes chicken pox and shingles. More antivira... more Background / Purpose: Varicella-zoster virus (VZV) causes chicken pox and shingles. More antiviral drugs are needed for VZV infections, but the drug pipeline was blocked because a small animal model was lacking. This poster describes the SCID-Hu mouse model of VZV replication in skin xenografts that has been successfully developed for testing antiviral drugs. Main conclusion: A recent study using the SCID-Hu mouse model of VZV replication compared an experimental compound, valyl-L-BHDU to acyclovir and valacyclovir, the standard of care. Valyl-L-BHDU was more effective at 30 mg/kg/day than acyclovir at 120 mg/kg/day, and valacyclovir at 200 mg/kg/day was effective but toxic.

Research paper thumbnail of Spontaneous cardiac calcinosis in BALB/cByJ mice

Comparative medicine, 2013

BALB/c mice are predisposed to dystrophic cardiac calcinosis-the mineralization of cardiac tissue... more BALB/c mice are predisposed to dystrophic cardiac calcinosis-the mineralization of cardiac tissues, especially the right ventricular epicardium. In previous reports, the disease appeared in aged animals and had an unknown etiology. In the current study, we report a substrain of BALB/c mice (BALB/cByJ) that develops disease early and with high frequency. Here we analyzed hearts grossly to identify the presence and measure the severity of disease and to compare BALB/c substrains. Histologic analysis and fluorescent and immunofluorescent microscopy were used to characterize the calcinotic lesions. BALB/cByJ mice exhibited more frequent and severe calcium deposition than did BALB/c mice of other substrains (90% compared with 3% at 5 wk). At this age, lesions covered an average of 30% of the total ventricular surface area in BALB/cByJ mice, compared with less than 1% in other strains. In bone-marrow-chimeric mice, green fluorescent protein was used as a marker to show that the lesions co...

Research paper thumbnail of Chemical Gating of Connexin Channels

Connexins, 2009

Abstract The physiology of gap junctions is regulated by changes in the micro-environment of the ... more Abstract The physiology of gap junctions is regulated by changes in the micro-environment of the cell. The most defined mechanism for such regulation is the closure of gap junction channels in response to acidification of the intracellular space, that is, pH gating or chemical gating. ...

Research paper thumbnail of Acidification-induced changes in Cx43 protein-protein interactions

Journal of Neurochemistry, 2008

ABSTRACT Astrocytic gap junctions close in response to low intracellular pH, a process that may o... more ABSTRACT Astrocytic gap junctions close in response to low intracellular pH, a process that may occur during ischemia. We propose that pH gating of Connexin43 (Cx43) involves binding of the carboxyl terminal domain (Cx43CT) to a pore-affiliated ‘receptor’ and, possibly, interaction of Cx43 with other molecular partners. We studied the role of intra– and intermolecular interactions in Cx43 pH gating. Peptides were made corresponding to intracellular regions of Cx43. Using Surface Plasmon resonance (SPR) we found pH dependent binding of the second half of the cytoplasmic loop to Cx43CT (Kd = 80 and 225 mm, pH 6.5 and 7.4, respectively). Binding was inhibited by preincubation with a synthetic peptide from region 346–362 of Cx43CT and by an antibody to this epitope, suggesting the binding site lies partially within this region. Nuclear magnetic resonance (NMR) studies showed formation of alpha helices in response to low pH in amino acid sequences VEMHL (aa 123–127) and IEEHGK (aa 139–143) in the loop, and a helical region within the suggested Cx43CT binding site. In addition, we found that acidification of astrocytes in vitro led to dissociation of Cx43 from its scaffold protein ZO-1. SPR showed that this was not due to pH dependence of Cx43-ZO-1 interaction (Kd = 2.23 mm at pH 7.4, 1.71 mm at pH 6.5) but to a strong pH–dependent interaction of Cx43 with c-Src (Kd = 0.63 mm at pH 7.4, 0.04 mm at pH 6.5) which caused ZO-1 to dissociate from Cx43CT. Separate experiments showed activation of astrocytic src at low pH. These changes in the composition of the Cx43 Nexus may play a major role in limiting tissue damage during brain ischemia. Acknowledgements: Supported by NIH grants NS 07098 (HSD) NS34931 & NS41282 (DCS) and GM57691 (MD).

Research paper thumbnail of Manipulation of gap junction proteins: effect on cellular coupling and impulse propagation

Journal of Electrocardiology, 2005

Research paper thumbnail of Letter to the Editor: Sequence-specific Resonance Assignments of the Tandem SH3 Domains in an Autoinhibitory form of p47 phox

Journal of Biomolecular NMR, 2000

... All the data were pro-cessed with nmrPipe (Delaglio et al., 1995). The 1HN, 15N and 13C backb... more ... All the data were pro-cessed with nmrPipe (Delaglio et al., 1995). The 1HN, 15N and 13C backbone resonances and those of the β carbons of p47phox (151-340) were assigned using the Olivia program (Yokochi and Inagaki, 2003) from http://fermi.pharm.hokudai.ac.jp ...

Research paper thumbnail of pH-Dependent Intramolecular Binding and Structure Involving Cx43 Cytoplasmic Domains

Journal of Biological Chemistry, 2002

pH-induced closure of connexin43 (Cx43) channels involves interaction of the Cx43 carboxyl-termin... more pH-induced closure of connexin43 (Cx43) channels involves interaction of the Cx43 carboxyl-terminal (Cx43CT) with a separate "receptor" domain. The receptor location and structure and whether the interaction is directly intramolecular are unknown. Here we show resonant mirror technology, enzyme-linked sorbent assays, and nuclear magnetic resonance (NMR) experiments demonstrating pH-dependent binding of Cx43CT to region 119 -144 of Cx43 (Cx43L2), which we propose is the receptor. NMR showed that acidification induced ␣-helical order in Cx43L2, whereas only a minor modification in Cx43CT structure was detected. These data provide the first demonstration of chemically induced structural order and binding between cytoplasmic connexin domains.

Research paper thumbnail of Molecular composition of the intercalated disc in a spontaneous canine animal model of arrhythmogenic right ventricular dysplasia/cardiomyopathy

Heart Rhythm, 2007

Background/Objective-Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/ C) is chara... more Background/Objective-Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/ C) is characterized by ventricular arrhythmias, sudden death, and fatty or fibrofatty replacement of right ventricular myocytes. Recent studies have noted an association between human ARVD/C and molecular remodeling of intercalated disc structures. However, progress has been constrained by limitations inherent to human studies. Here, we studied the molecular composition of the intercalated disc structure in a naturally occurring animal model of ARVD/C (boxer dogs).

Research paper thumbnail of Design and characterization of the first peptidomimetic molecule that prevents acidification-induced closure of cardiac gap junctions

Heart Rhythm, 2010

Background-Gap junctions are potential targets for pharmacological intervention. We have previous... more Background-Gap junctions are potential targets for pharmacological intervention. We have previously developed a series of peptide sequences that prevent closure of Cx43 channels, bind to cardiac Cx43 and prevent acidification-induced uncoupling of cardiac gap junctions.

Research paper thumbnail of Characterization of the molecular phenotype of two arrhythmogenic right ventricular cardiomyopathy (ARVC)-related plakophilin-2 (PKP2) mutations

Heart Rhythm, 2008

BACKGROUND-Arrhythmogenic right ventricular cardiomyopathy (ARVC), has been linked to mutations i... more BACKGROUND-Arrhythmogenic right ventricular cardiomyopathy (ARVC), has been linked to mutations in desmosomal proteins, including plakophilin2 (PKP2). Little is known about the changes in cellular function and structure that follow expression of ARVC-relevant PKP2 mutations.

Research paper thumbnail of Loss of electrical communication, but not plaque formation, after mutations in the cytoplasmic loop of connexin43

Heart Rhythm, 2004

The aim of this study was to determine if the structural integrity of a region in the cytoplasmic... more The aim of this study was to determine if the structural integrity of a region in the cytoplasmic loop (amino acids 119-144; region "L2") of connexin43 (Cx43) is necessary to maintain normal channel function. Cx43 is the most abundant gap junction protein in the heart. The ability of these channels to close under pathologic conditions such as ischemia may be a key substrate for cardiac arrhythmias. Previous studies have shown that Cx43 regulation involves the intramolecular interaction of its carboxyl terminal domain (a "gating particle") with a separate region of the molecule acting as a receptor. We recently proposed that a region in the cytoplasmic loop of Cx43 (amino acids 119-144; region "L2") might function as a receptor. Using site-directed mutagenesis and patch clamp analysis, as well as fluorescent microscopy, we examined gap junction plaque formation and channel properties of Cx43 L2 mutants. Deletions of 5 to 6 amino acids within the L2 domain interfered with the formation of functional gap junction channels, although gap junction plaques were clearly visible. Selected point mutations in the region (including those present in patients with oculodentodigital dysplasia) caused modifications ranging from complete channel closure to changes in unitary conductance. These results show that the L2 region is essential for maintenance of the normal architecture of the channel pore. This information is consistent with the notion that the L2 region could be a receptor for the carboxy terminal domain; the latter interaction would lead to channel closure under conditions such as myocardial ischemia and infarction.

Research paper thumbnail of Interactions Between Ankyrin-G, Plakophilin-2, and Connexin43 at the Cardiac Intercalated Disc

Circulation Research, 2011

Rationale-The early description of the intercalated disc defined three structures, all of them in... more Rationale-The early description of the intercalated disc defined three structures, all of them involved in cell-cell communication: desmosomes, gap junctions and adherens junctions. Current evidence demonstrates that molecules not involved in providing a physical continuum between cells, also populate the intercalated disc. Key among them is the voltage-gated sodium channel (VGSC) complex. An important component of this complex is the cytoskeletal adaptor protein ankyrin-G (AnkG).

Research paper thumbnail of Identification of a Novel Peptide That Interferes With the Chemical Regulation of Connexin43

Circulation Research, 2006

located on the World Wide Web at:

Research paper thumbnail of Novel Pharmacophores of Connexin43 Based on the "RXP" Series of Cx43-Binding Peptides

Circulation Research, 2009

located on the World Wide Web at:

Research paper thumbnail of Connexin43 Remodeling Caused by Inhibition of Plakophilin-2 Expression in Cardiac Cells

Circulation Research, 2007

Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc.... more Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc. Here, we asked whether the presence of plakophilin (PKP)2, a component of the desmosome, is essential for the proper function and distribution of the gap junction protein connexin (Cx)43. We used RNA silencing technology to decrease the expression of PKP2 in cardiac cells (ventricular myocytes, as well as epicardium-derived cells) obtained from neonatal rat hearts. We evaluated the content, distribution, and function of Cx43 gap junctions. Our results show that loss of PKP2 expression led to a decrease in total Cx43 content, a significant redistribution of Cx43 to the intracellular space, and a decrease in dye coupling between cells. Separate experiments showed that Cx43 and PKP2 can coexist in the same macromolecular complex. Our results support the notion of a molecular crosstalk between desmosomal and gap junction proteins. The results are discussed in the context of arrhythmogenic right ventricular cardiomyopathy, an inherited disease involving mutations in desmosomal proteins, including PKP2. (Circ Res. 2007;101:703-711.)

Research paper thumbnail of Connexin43 Remodeling Caused by Inhibition of Plakophilin-2 Expression in Cardiac Cells

Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc.... more Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc. Here, we asked whether the presence of plakophilin (PKP)2, a component of the desmosome, is essential for the proper function and distribution of the gap junction protein connexin (Cx)43. We used RNA silencing technology to decrease the expression of PKP2 in cardiac cells (ventricular myocytes, as well as epicardium-derived cells) obtained from neonatal rat hearts. We evaluated the content, distribution, and function of Cx43 gap junctions. Our results show that loss of PKP2 expression led to a decrease in total Cx43 content, a significant redistribution of Cx43 to the intracellular space, and a decrease in dye coupling between cells. Separate experiments showed that Cx43 and PKP2 can coexist in the same macromolecular complex. Our results support the notion of a molecular crosstalk between desmosomal and gap junction proteins. The results are discussed in the context of arrhythmogenic right ventricular cardiomyopathy, an inherited disease involving mutations in desmosomal proteins, including PKP2. (Circ Res. 2007;101:703-711.)

Research paper thumbnail of Peptide Gap Junction Modulators

Research paper thumbnail of Abstract 1911: eNOS is a Binding Partner for the Gap Junction Protein Cx37 in Endothelial Cells

Circulation, Oct 28, 2008

Research paper thumbnail of Severity of autoimmune myocarditis is influenced by Connexin43 expression

The Journal of Immunology, May 1, 2012

Research paper thumbnail of Abstract 18393: Plakophilin-2, Ankyrin-G and Connexin43 Mutually Interact to Regulate Intercellular Coupling and Sodium Channel Function. Implications to Arrhythmogenic Cardiomyopathies?

Circulation, Nov 23, 2010

Research paper thumbnail of Humanized mice and _in vivo_ bioluminescence imaging: tools for testing antiviral drugs for varicella-zoster virus

Background / Purpose: Varicella-zoster virus (VZV) causes chicken pox and shingles. More antivira... more Background / Purpose: Varicella-zoster virus (VZV) causes chicken pox and shingles. More antiviral drugs are needed for VZV infections, but the drug pipeline was blocked because a small animal model was lacking. This poster describes the SCID-Hu mouse model of VZV replication in skin xenografts that has been successfully developed for testing antiviral drugs. Main conclusion: A recent study using the SCID-Hu mouse model of VZV replication compared an experimental compound, valyl-L-BHDU to acyclovir and valacyclovir, the standard of care. Valyl-L-BHDU was more effective at 30 mg/kg/day than acyclovir at 120 mg/kg/day, and valacyclovir at 200 mg/kg/day was effective but toxic.

Research paper thumbnail of Spontaneous cardiac calcinosis in BALB/cByJ mice

Comparative medicine, 2013

BALB/c mice are predisposed to dystrophic cardiac calcinosis-the mineralization of cardiac tissue... more BALB/c mice are predisposed to dystrophic cardiac calcinosis-the mineralization of cardiac tissues, especially the right ventricular epicardium. In previous reports, the disease appeared in aged animals and had an unknown etiology. In the current study, we report a substrain of BALB/c mice (BALB/cByJ) that develops disease early and with high frequency. Here we analyzed hearts grossly to identify the presence and measure the severity of disease and to compare BALB/c substrains. Histologic analysis and fluorescent and immunofluorescent microscopy were used to characterize the calcinotic lesions. BALB/cByJ mice exhibited more frequent and severe calcium deposition than did BALB/c mice of other substrains (90% compared with 3% at 5 wk). At this age, lesions covered an average of 30% of the total ventricular surface area in BALB/cByJ mice, compared with less than 1% in other strains. In bone-marrow-chimeric mice, green fluorescent protein was used as a marker to show that the lesions co...

Research paper thumbnail of Chemical Gating of Connexin Channels

Connexins, 2009

Abstract The physiology of gap junctions is regulated by changes in the micro-environment of the ... more Abstract The physiology of gap junctions is regulated by changes in the micro-environment of the cell. The most defined mechanism for such regulation is the closure of gap junction channels in response to acidification of the intracellular space, that is, pH gating or chemical gating. ...

Research paper thumbnail of Acidification-induced changes in Cx43 protein-protein interactions

Journal of Neurochemistry, 2008

ABSTRACT Astrocytic gap junctions close in response to low intracellular pH, a process that may o... more ABSTRACT Astrocytic gap junctions close in response to low intracellular pH, a process that may occur during ischemia. We propose that pH gating of Connexin43 (Cx43) involves binding of the carboxyl terminal domain (Cx43CT) to a pore-affiliated ‘receptor’ and, possibly, interaction of Cx43 with other molecular partners. We studied the role of intra– and intermolecular interactions in Cx43 pH gating. Peptides were made corresponding to intracellular regions of Cx43. Using Surface Plasmon resonance (SPR) we found pH dependent binding of the second half of the cytoplasmic loop to Cx43CT (Kd = 80 and 225 mm, pH 6.5 and 7.4, respectively). Binding was inhibited by preincubation with a synthetic peptide from region 346–362 of Cx43CT and by an antibody to this epitope, suggesting the binding site lies partially within this region. Nuclear magnetic resonance (NMR) studies showed formation of alpha helices in response to low pH in amino acid sequences VEMHL (aa 123–127) and IEEHGK (aa 139–143) in the loop, and a helical region within the suggested Cx43CT binding site. In addition, we found that acidification of astrocytes in vitro led to dissociation of Cx43 from its scaffold protein ZO-1. SPR showed that this was not due to pH dependence of Cx43-ZO-1 interaction (Kd = 2.23 mm at pH 7.4, 1.71 mm at pH 6.5) but to a strong pH–dependent interaction of Cx43 with c-Src (Kd = 0.63 mm at pH 7.4, 0.04 mm at pH 6.5) which caused ZO-1 to dissociate from Cx43CT. Separate experiments showed activation of astrocytic src at low pH. These changes in the composition of the Cx43 Nexus may play a major role in limiting tissue damage during brain ischemia. Acknowledgements: Supported by NIH grants NS 07098 (HSD) NS34931 & NS41282 (DCS) and GM57691 (MD).

Research paper thumbnail of Manipulation of gap junction proteins: effect on cellular coupling and impulse propagation

Journal of Electrocardiology, 2005

Research paper thumbnail of Letter to the Editor: Sequence-specific Resonance Assignments of the Tandem SH3 Domains in an Autoinhibitory form of p47 phox

Journal of Biomolecular NMR, 2000

... All the data were pro-cessed with nmrPipe (Delaglio et al., 1995). The 1HN, 15N and 13C backb... more ... All the data were pro-cessed with nmrPipe (Delaglio et al., 1995). The 1HN, 15N and 13C backbone resonances and those of the β carbons of p47phox (151-340) were assigned using the Olivia program (Yokochi and Inagaki, 2003) from http://fermi.pharm.hokudai.ac.jp ...

Research paper thumbnail of pH-Dependent Intramolecular Binding and Structure Involving Cx43 Cytoplasmic Domains

Journal of Biological Chemistry, 2002

pH-induced closure of connexin43 (Cx43) channels involves interaction of the Cx43 carboxyl-termin... more pH-induced closure of connexin43 (Cx43) channels involves interaction of the Cx43 carboxyl-terminal (Cx43CT) with a separate "receptor" domain. The receptor location and structure and whether the interaction is directly intramolecular are unknown. Here we show resonant mirror technology, enzyme-linked sorbent assays, and nuclear magnetic resonance (NMR) experiments demonstrating pH-dependent binding of Cx43CT to region 119 -144 of Cx43 (Cx43L2), which we propose is the receptor. NMR showed that acidification induced ␣-helical order in Cx43L2, whereas only a minor modification in Cx43CT structure was detected. These data provide the first demonstration of chemically induced structural order and binding between cytoplasmic connexin domains.

Research paper thumbnail of Molecular composition of the intercalated disc in a spontaneous canine animal model of arrhythmogenic right ventricular dysplasia/cardiomyopathy

Heart Rhythm, 2007

Background/Objective-Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/ C) is chara... more Background/Objective-Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/ C) is characterized by ventricular arrhythmias, sudden death, and fatty or fibrofatty replacement of right ventricular myocytes. Recent studies have noted an association between human ARVD/C and molecular remodeling of intercalated disc structures. However, progress has been constrained by limitations inherent to human studies. Here, we studied the molecular composition of the intercalated disc structure in a naturally occurring animal model of ARVD/C (boxer dogs).

Research paper thumbnail of Design and characterization of the first peptidomimetic molecule that prevents acidification-induced closure of cardiac gap junctions

Heart Rhythm, 2010

Background-Gap junctions are potential targets for pharmacological intervention. We have previous... more Background-Gap junctions are potential targets for pharmacological intervention. We have previously developed a series of peptide sequences that prevent closure of Cx43 channels, bind to cardiac Cx43 and prevent acidification-induced uncoupling of cardiac gap junctions.

Research paper thumbnail of Characterization of the molecular phenotype of two arrhythmogenic right ventricular cardiomyopathy (ARVC)-related plakophilin-2 (PKP2) mutations

Heart Rhythm, 2008

BACKGROUND-Arrhythmogenic right ventricular cardiomyopathy (ARVC), has been linked to mutations i... more BACKGROUND-Arrhythmogenic right ventricular cardiomyopathy (ARVC), has been linked to mutations in desmosomal proteins, including plakophilin2 (PKP2). Little is known about the changes in cellular function and structure that follow expression of ARVC-relevant PKP2 mutations.

Research paper thumbnail of Loss of electrical communication, but not plaque formation, after mutations in the cytoplasmic loop of connexin43

Heart Rhythm, 2004

The aim of this study was to determine if the structural integrity of a region in the cytoplasmic... more The aim of this study was to determine if the structural integrity of a region in the cytoplasmic loop (amino acids 119-144; region "L2") of connexin43 (Cx43) is necessary to maintain normal channel function. Cx43 is the most abundant gap junction protein in the heart. The ability of these channels to close under pathologic conditions such as ischemia may be a key substrate for cardiac arrhythmias. Previous studies have shown that Cx43 regulation involves the intramolecular interaction of its carboxyl terminal domain (a "gating particle") with a separate region of the molecule acting as a receptor. We recently proposed that a region in the cytoplasmic loop of Cx43 (amino acids 119-144; region "L2") might function as a receptor. Using site-directed mutagenesis and patch clamp analysis, as well as fluorescent microscopy, we examined gap junction plaque formation and channel properties of Cx43 L2 mutants. Deletions of 5 to 6 amino acids within the L2 domain interfered with the formation of functional gap junction channels, although gap junction plaques were clearly visible. Selected point mutations in the region (including those present in patients with oculodentodigital dysplasia) caused modifications ranging from complete channel closure to changes in unitary conductance. These results show that the L2 region is essential for maintenance of the normal architecture of the channel pore. This information is consistent with the notion that the L2 region could be a receptor for the carboxy terminal domain; the latter interaction would lead to channel closure under conditions such as myocardial ischemia and infarction.

Research paper thumbnail of Interactions Between Ankyrin-G, Plakophilin-2, and Connexin43 at the Cardiac Intercalated Disc

Circulation Research, 2011

Rationale-The early description of the intercalated disc defined three structures, all of them in... more Rationale-The early description of the intercalated disc defined three structures, all of them involved in cell-cell communication: desmosomes, gap junctions and adherens junctions. Current evidence demonstrates that molecules not involved in providing a physical continuum between cells, also populate the intercalated disc. Key among them is the voltage-gated sodium channel (VGSC) complex. An important component of this complex is the cytoskeletal adaptor protein ankyrin-G (AnkG).

Research paper thumbnail of Identification of a Novel Peptide That Interferes With the Chemical Regulation of Connexin43

Circulation Research, 2006

located on the World Wide Web at:

Research paper thumbnail of Novel Pharmacophores of Connexin43 Based on the "RXP" Series of Cx43-Binding Peptides

Circulation Research, 2009

located on the World Wide Web at:

Research paper thumbnail of Connexin43 Remodeling Caused by Inhibition of Plakophilin-2 Expression in Cardiac Cells

Circulation Research, 2007

Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc.... more Desmosomes and gap junctions are distinct structural components of the cardiac intercalated disc. Here, we asked whether the presence of plakophilin (PKP)2, a component of the desmosome, is essential for the proper function and distribution of the gap junction protein connexin (Cx)43. We used RNA silencing technology to decrease the expression of PKP2 in cardiac cells (ventricular myocytes, as well as epicardium-derived cells) obtained from neonatal rat hearts. We evaluated the content, distribution, and function of Cx43 gap junctions. Our results show that loss of PKP2 expression led to a decrease in total Cx43 content, a significant redistribution of Cx43 to the intracellular space, and a decrease in dye coupling between cells. Separate experiments showed that Cx43 and PKP2 can coexist in the same macromolecular complex. Our results support the notion of a molecular crosstalk between desmosomal and gap junction proteins. The results are discussed in the context of arrhythmogenic right ventricular cardiomyopathy, an inherited disease involving mutations in desmosomal proteins, including PKP2. (Circ Res. 2007;101:703-711.)