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.
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...
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. ...
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).
... 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 ...
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.
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.
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...
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. ...
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).
... 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 ...
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.
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Papers by Wanda Coombs