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Yeh HI, Lai YJ, Lee YN, Chen YJ, Chen YC, Chen CC, Chen SA, Lin CI, Tsai CH. Differential expression of connexin43 gap junctions in cardiomyocytes isolated from canine thoracic veins. J Histochem Cytochem 2003; 51:259-66. [PMID: 12533535 DOI: 10.1177/002215540305100215] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We investigated the phenotypic features of cardiomyocytes, including the gap junctions, in the myocardial sleeve of thoracic veins. Single cardiomyocytes, isolated from the canine pulmonary veins (PV) and superior vena cava (SVC) using digestive enzymes, were examined by immunoconfocal microscopy using antisera against connexin43 (Cx43), Cx40, and other cell markers. The results showed that isolated cardiomyocytes displayed rod shapes of various sizes, ranging from <50 microm to >200 microm in length, and all the cells expressed alpha-actinin and vinculin. Gap junctions made of various amounts of Cx43 and Cx40 were found at the cell borders. These two connexins were extensively co-localized. Comparison between the thoracic veins showed that cells of the SVC contained more Cx43 gap junctions (total Cx43 gap junctions area per cell surface area, 4.0 +/- 0.2% vs 1.5 +/- 0.2%; p<0.01). In addition, for single-nucleus cells, those from the PV were longer (103.7 +/- 3.6 vs 85.0 +/- 3.1 microm; p<0.01) but narrower (14.4 +/- 0.5 vs 16.9 +/- 0.9 microm; p<0.01). In conclusion, canine thoracic veins contain cardiomyocytes with differences in shape and gap junctions, suggesting that the electrical conduction properties may be different between the thoracic veins.
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MESH Headings
- Animals
- Connexin 43/biosynthesis
- Connexin 43/immunology
- Coronary Vessels/cytology
- Coronary Vessels/metabolism
- Coronary Vessels/ultrastructure
- Dogs
- Gap Junctions/metabolism
- Immune Sera
- Immunohistochemistry
- Microscopy, Confocal
- Muscle Cells/metabolism
- Muscle Cells/ultrastructure
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/ultrastructure
- Pulmonary Veins/cytology
- Pulmonary Veins/metabolism
- Pulmonary Veins/ultrastructure
- Thorax
- Vena Cava, Superior/cytology
- Vena Cava, Superior/metabolism
- Vena Cava, Superior/ultrastructure
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Affiliation(s)
- Hung-I Yeh
- Department of Internal Medicine, Mackay Memorial Hospital and Mackay Junior College of Nursing, Taipei, Taiwan
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Lee YN, Yeh HI, Tian TY, Lu WW, Ko YS, Tsai CH. 2',5'-Dihydroxychalcone down-regulates endothelial connexin43 gap junctions and affects MAP kinase activation. Toxicology 2002; 179:51-60. [PMID: 12204542 DOI: 10.1016/s0300-483x(02)00289-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined the effect of 2',5'-dihydroxychalcone on connexin43 (Cx43) expression and gap-junctional communication in human umbilical vein endothelial cells (HUVEC). The result showed that expression of Cx43 is rapidly reduced by 2',5'-dihydroxychalcone in a dose-dependent manner, Concomitantly, the communication function, determined by fluorescence recovery after photobleaching (FRAP), is decreased. We further investigated whether the mitogen-activated protein (MAP) kinase and the degradation pathway of gap junctions are involved in these processes. Although the change of Cx43 is not affected by the level of fetal calf serum (FCS) used in the medium, activation of MAP kinase varies, depending on the FCS level. At a low level (0.5%), the chalcone inhibits the activation, like PD98059, a specific inhibitor of MAP kinase kinase. However, at a high level (20%), MAP kinase is activated. On the other hand, the chalcone's down-regulating effect on Cx43, while is totally blocked by protease inhibitors leupeptin and N-acetyl-leucyl-norleucinal (ALLN), persists in the presence of PD98059, We concluded that 2',5'-dihydroxychalcone down-regulates Cx43 expression and gap-junctional communication in the HUVEC via enhancement of the proteolysis pathway, and this compound possesses dual effects on MAP kinase activation.
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Affiliation(s)
- Yi-Nan Lee
- Cardiovascular Division, Department of Internal Medicine, Mackay Memorial Hospital, Mackay Junior College of Nursing, Taipei Medical University, Taipei, Taiwan, ROC
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Rummery NM, Hickey H, McGurk G, Hill CE. Connexin37 is the major connexin expressed in the media of caudal artery. Arterioscler Thromb Vasc Biol 2002; 22:1427-32. [PMID: 12231561 DOI: 10.1161/01.atv.0000028814.45706.e5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To determine the connexins (Cxs) involved in intercellular coupling within vascular muscle, the present study has quantified mRNA and protein expression for Cx37, Cx40, Cx43, and Cx45 in the caudal artery (CA) and thoracic aorta (ThA) of the rat. METHODS AND RESULTS Real-time polymerase chain reaction and immunohistochemistry identified Cx37 as the most abundantly expressed Cx in the CA, with fine punctate staining observed in the media. Conversely, mRNA for Cx43 was 40-fold greater in the ThA than in the CA, with punctate staining in the endothelium and media of the ThA but confined to the endothelium in the CA. Western blotting confirmed the differences in the relative amounts of Cx43 between the 2 vessels. For both arteries, Cx45 was expressed to a lesser degree in the media but not in the endothelium, whereas Cx40 was found only in the endothelium. Cx37, Cx40, and Cx43 were expressed in the endothelium of both vessels, although the density of Cx40 plaques was significantly greater in the CA. CONCLUSIONS The demonstration of Cx37 as the dominant Cx in the media of the CA highlights the potential heterogeneity in Cx involvement in vascular smooth muscle.
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MESH Headings
- Animals
- Antibodies/metabolism
- Aorta, Thoracic/chemistry
- Aorta, Thoracic/metabolism
- Arteries/metabolism
- Blotting, Western
- Connexin 43/biosynthesis
- Connexins/biosynthesis
- Connexins/immunology
- Endothelium, Vascular/chemistry
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Immunohistochemistry
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/metabolism
- Rats
- Sacrococcygeal Region/blood supply
- Tunica Media/chemistry
- Tunica Media/metabolism
- Gap Junction alpha-5 Protein
- Gap Junction alpha-4 Protein
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Affiliation(s)
- Nicole M Rummery
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australia.
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Errede M, Benagiano V, Girolamo F, Flace P, Bertossi M, Roncali L, Virgintino D. Differential expression of connexin43 in foetal, adult and tumour-associated human brain endothelial cells. THE HISTOCHEMICAL JOURNAL 2002; 34:265-71. [PMID: 12769257 DOI: 10.1023/a:1023344106815] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Connexin43 (Cx43), the main protein constituting the gap junctions between astrocytes, has previously been demonstrated in endothelial cells of somatic vessels where the intercellular coupling that it provides plays a role in endothelial proliferation and migration. In this study, Cx43 expression was analysed in human brain microvascular endothelial cells of the cortical plate of 18-week foetal telencephalon, in adult cerebral cortex and glioma (astrocytomas). The study was carried out by immunocytochemistry utilizing a Cx43 monoclonal antibody and a polyclonal antibody anti-GLUT1 (glucose transporter isoform 1) to identify the endothelial cells and to localize Cx43. Endothelial Cx43 is differently expressed in the cortical plate, cerebral cortex and astrocytoma. Within the cortical plate and tumour, Cx43 is highly expressed in microvascular endothelial cells whereas it is virtually absent in the cerebral cortex microvessels. The high expression of the gap junction protein in developing brain, as well as in brain tumours, may be related to the growth status of the microvessels during brain and tumour angiogenesis. The lack of endothelial Cx43 in the cerebral cortex is in agreement with the characteristics of the mature brain endothelial cells that are sealed by tight junctions. In conclusion, the results indicate that endothelial Cx43 expression is developmentally regulated in the normal human brain and suggest that it is controlled by the microenvironment in both normal and tumour-related conditions.
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Affiliation(s)
- Mariella Errede
- Department of Human Anatomy and Histology, University of Bari Medical School, Polyclinics, piazza Giulio Cesare, 70124 Bari, Italy
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Sato T, Haimovici R, Kao R, Li AF, Roy S. Downregulation of connexin 43 expression by high glucose reduces gap junction activity in microvascular endothelial cells. Diabetes 2002; 51:1565-71. [PMID: 11978657 DOI: 10.2337/diabetes.51.5.1565] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Impairment of retinal vascular homeostasis is associated with the development and progression of diabetic retinopathy involving gap junction intercellular communication (GJIC) activity. The principal gap junction protein of intercellular communication, connexin, was investigated to determine the effects of high glucose concentrations on the expression of endothelial-specific connexins (Cx37, Cx40, and Cx43), connexin phosphorylation pattern, and GJIC activity. Rat microvascular endothelial (RME) cells grown in high (30 mmol/l)-glucose medium for 9 days had reduced Cx43 expression: Cx43 mRNA (68 +/- 13% of control; P = 0.019, n = 5) and protein (55.6 +/- 16% of control; P = 0.003, n = 5) levels were reduced; however, Cx37 and Cx40 expression was not affected. Using alkaline phosphatase and Western blot analyses, we identified three forms of Cx43: a nonphosphorylated form (P0) and two phosphorylated forms (P1 and P2). Expression of all three forms was decreased in cells grown in high-glucose medium: PO, 73 +/- 15% of control (P = 0.04); P1, 57 +/- 16% of control (P = 0.01); and P2, 42 +/- 22% of control (P = 0.006). Using immunofluorescence microscopy, we observed Cx43 localization at specific sites of contact (plaques) between adjacent cells. In cells grown in high-glucose medium, we observed reduced plaque counts (63 +/- 6% of control; P = 0.009) and decreased intensity of Cx43 immunofluorescence compared with cells grown in normal medium. Furthermore, using scrape load dye transfer (SLDT) technique, we found that these cells exhibited reduced GJIC activity (60% of control; P = 0.01, n = 5). The reduction in GJIC activity correlated with the decreased Cx43 protein levels (r = 0.9). These results indicate that high glucose concentrations inhibited GJIC activity by reducing Cx43 synthesis in RME cells. Impaired intercellular communication may contribute to breakdown of homeostatic balance in diabetic microangiopathy.
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Affiliation(s)
- Tsuyoshi Sato
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Kwak BR, Mulhaupt F, Veillard N, Gros DB, Mach F. Altered pattern of vascular connexin expression in atherosclerotic plaques. Arterioscler Thromb Vasc Biol 2002; 22:225-30. [PMID: 11834520 DOI: 10.1161/hq0102.104125] [Citation(s) in RCA: 167] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Paracrine cell-to-cell interactions are crucial events during atherogenesis. However, little is known about the role of direct intercellular communication via gap junctions during this process. We have investigated the expression pattern of 3 vascular gap junction proteins (connexins) in mouse and human atherosclerotic plaques. Low density lipoprotein receptor-deficient mice were fed a high-fat diet for 0, 6, 10, or 14 weeks to induce different stages of atherosclerosis. Connexin37 (Cx37) and Cx40 were detected in the endothelium, and Cx43 was detected in the media of nondiseased aortas. In early atheromas, endothelial and medial connexin expression remained unchanged, and "islets" of Cx43 in smooth muscle cells and Cx37 in macrophages were observed in the neointima. In advanced atheromas, Cx37 was detected in medial smooth muscle cells and in macrophages in the lipid core but not in the endothelium covering the plaques. Cx40 could also no longer be detected in the endothelium covering the plaques. Cx43, on the other hand, was detected in the endothelium covering the shoulder of the plaques and also sparsely in neointimal smooth muscle cells. Similar results were obtained for human carotid arteries. In conclusion, vascular connexins are differentially expressed by atheroma-associated cells within lesions. These observations suggest a role for gap junctional intercellular communication during atherogenesis.
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Affiliation(s)
- Brenda R Kwak
- Division of Cardiology, Department of Medicine, University Hospital Geneva, Geneva, Switzerland
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Rummery NM, McKenzie KUS, Whitworth JA, Hill CE. Decreased endothelial size and connexin expression in rat caudal arteries during hypertension. J Hypertens 2002; 20:247-53. [PMID: 11821709 DOI: 10.1097/00004872-200202000-00014] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Hypertension is accompanied by endothelial dysfunction. The present study has investigated endothelial cell morphology and connexin expression in the caudal artery of the rat during the development of hypertension. METHODS A significant increase in systolic blood pressure was detected from 9 weeks of age in spontaneously hypertensive male rats (SHR) compared to normotensive Wistar-Kyoto (WKY) rats, reaching a maximum by 11-12 weeks of age. Immunohistochemistry was used to quantify cell size and expression of connexins (Cxs) 37, 40 and 43 in the endothelium of prehypertensive (3-week-old) and hypertensive (12-week-old) rats. RESULTS At 12 weeks, the size of endothelial cells and the expression of all three Cxs per endothelial cell were significantly less in SHR than WKY rats. At 3 weeks, there was no significant difference in cell size nor in the expression of Cxs 37 or 43; however, expression of Cx40 was significantly lower in SHR than in WKY rats. Between 3 and 12 weeks in WKY rats, there was no change in endothelial cell size, nor in the expression of Cxs 37, 40 and 43. In SHR, both cell size and Cx expression per endothelial cell were significantly decreased during the same developmental period, with a significant decrease in the density of Cx40 plaques. CONCLUSION The development of hypertension in the SHR is accompanied by significant decreases in endothelial cell size and expression of Cx40, which may contribute to the endothelial dysfunction present in hypertension.
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Affiliation(s)
- Nicole M Rummery
- Autonomic Synapse Group, Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australia.
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Abstract
BACKGROUND A recent study shows that a C1019T polymorphism of the gene encoding the gap junction protein connexin37 contributes to the genesis of atherosclerotic plaques in human carotid artery. However, whether such a polymorphism can be used as a prognostic marker in atherosclerotic disease of other arterial sites, such as coronary artery disease, is not known. METHODS We analyzed the allelic status in 177 subjects with coronary artery disease (age, 61+/-11 years; male/female, 120/57) and 102 controls (60+/-11 years; male/female, 70/32). Both groups were matched, before genotype analysis, for a variety of other traditional risk factors, including body mass index, smoking status, levels of blood pressure, sugar, creatinine, and lipid profiles, in addition to age and sex. RESULTS The T allele was less frequently seen in the control group, compared to the disease group (10.7 vs. 20.1%, TT+TC vs. CC, P<0.01). Subsequent analysis demonstrated that a significant difference existed in the male (9.2 vs. 22.8%, TT+TC vs. CC, P<0.005), but not in the female. Another finding was that the T allele frequency in all participants was less than 15%, markedly lower than that reported in non-Taiwanese. CONCLUSIONS The observation indicates that the polymorphism in the connexin37 gene potentially plays a role in the manifestation of coronary atherosclerosis in Taiwan.
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Affiliation(s)
- H I Yeh
- Department of Internal Medicine, Mackay Memorial Hospital, Taipei Medical College, Taipei, Taiwan, ROC
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