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Juin SK, Ouseph R, Gondim DD, Jala VR, Sen U. Diabetic Nephropathy and Gaseous Modulators. Antioxidants (Basel) 2023; 12:antiox12051088. [PMID: 37237955 DOI: 10.3390/antiox12051088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/05/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Diabetic nephropathy (DN) remains the leading cause of vascular morbidity and mortality in diabetes patients. Despite the progress in understanding the diabetic disease process and advanced management of nephropathy, a number of patients still progress to end-stage renal disease (ESRD). The underlying mechanism still needs to be clarified. Gaseous signaling molecules, so-called gasotransmitters, such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), have been shown to play an essential role in the development, progression, and ramification of DN depending on their availability and physiological actions. Although the studies on gasotransmitter regulations of DN are still emerging, the evidence revealed an aberrant level of gasotransmitters in patients with diabetes. In studies, different gasotransmitter donors have been implicated in ameliorating diabetic renal dysfunction. In this perspective, we summarized an overview of the recent advances in the physiological relevance of the gaseous molecules and their multifaceted interaction with other potential factors, such as extracellular matrix (ECM), in the severity modulation of DN. Moreover, the perspective of the present review highlights the possible therapeutic interventions of gasotransmitters in ameliorating this dreaded disease.
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Affiliation(s)
- Subir Kumar Juin
- Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Microbiology & Immunology, Brown Cancer Center, Center for Microbiomics, Inflammation and Pathogenicity, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Rosemary Ouseph
- Division of Nephrology & Hypertension, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Dibson Dibe Gondim
- Department of Pathology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Venkatakrishna Rao Jala
- Department of Microbiology & Immunology, Brown Cancer Center, Center for Microbiomics, Inflammation and Pathogenicity, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Utpal Sen
- Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
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2
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Price GW, Potter JA, Williams BM, Cliff CL, Squires PE, Hills CE. Connexin-mediated cell communication in the kidney: A potential therapeutic target for future intervention of diabetic kidney disease?: Joan Mott Prize Lecture. Exp Physiol 2020; 105:219-229. [PMID: 31785013 DOI: 10.1113/ep087770] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 11/19/2019] [Indexed: 12/21/2022]
Abstract
The ability of cells to communicate and synchronise their activity is essential for the maintenance of tissue structure, integrity and function. A family of membrane-bound proteins called connexins are largely responsible for mediating the local transfer of information between cells. Assembled in the cell membrane as a hexameric connexon, they either function as a conduit for paracrine signalling, forming a transmembrane hemi-channel, or, if aligned with connexons on neighbouring cells, form a continuous aqueous pore or gap junction, which allows for the direct transmission of metabolic and electrical signals. Regulation of connexin synthesis and activity is critical to cellular function, and a number of diseases are attributed to changes in the expression and/or function of these important proteins. A link between hyperglycaemia, connexin expression, altered nucleotide concentrations and impaired function highlights a potential role for connexin-mediated cell communication in complications of diabetes. In the diabetic kidney, glycaemic injury is the leading cause of end-stage renal failure, reflecting multiple aetiologies including glomerular hyperfiltration, albuminuria, increased deposition of extracellular matrix and tubulointerstitial fibrosis. Loss of connexin-mediated cell-to-cell communication in diabetic nephropathy may represent an early sign of disease progression, but our understanding of the process remains severely limited. This review focuses on recent evidence demonstrating that glucose-evoked changes in connexin-mediated cell communication and associated purinergic signalling may contribute to the pathogenesis of kidney disease in diabetes, highlighting the tantalising potential of targeting these proteins as a novel therapeutic intervention.
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Affiliation(s)
- Gareth W Price
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Joe A Potter
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Bethany M Williams
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Chelsy L Cliff
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Paul E Squires
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Claire E Hills
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
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Zhang J, Qu HY, Song J, Wei J, Jiang S, Wang L, Wang L, Buggs J, Liu R. Enhanced hemodynamic responses to angiotensin II in diabetes are associated with increased expression and activity of AT1 receptors in the afferent arteriole. Physiol Genomics 2017; 49:531-540. [PMID: 28842434 DOI: 10.1152/physiolgenomics.00025.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/21/2017] [Accepted: 08/21/2017] [Indexed: 12/28/2022] Open
Abstract
The prevalence of hypertension is about twofold higher in diabetic than in nondiabetic subjects. Hypertension aggravates the progression of diabetic complications, especially diabetic nephropathy. However, the mechanisms for the development of hypertension in diabetes have not been elucidated. We hypothesized that enhanced constrictive responsiveness of renal afferent arterioles (Af-Art) to angiotensin II (ANG II) mediated by ANG II type 1 (AT1) receptors contributes to the development of hypertension in diabetes. In response to an acute bolus intravenous injection of ANG II, alloxan-induced diabetic mice exhibited a higher mean arterial pressure (MAP) (119.1 ± 3.8 vs. 106.2 ± 3.5 mmHg) and a lower renal blood flow (0.25 ± 0.07 vs. 0.52 ± 0.14 ml/min) compared with nondiabetic mice. In response to chronic ANG II infusion, the MAP measured with telemetry increased by 55.8 ± 6.5 mmHg in diabetic mice, but only by 32.3 ± 3.8 mmHg in nondiabetic mice. The mRNA level of AT1 receptor increased by ~10-fold in isolated Af-Art of diabetic mice compared with nondiabetic mice, whereas ANG II type 2 (AT2) receptor expression did not change. The ANG II dose-response curve of the Af-Art was significantly enhanced in diabetic mice. Moreover, the AT1 receptor antagonist, losartan, blocked the ANG II-induced vasoconstriction in both diabetic mice and nondiabetic mice. In conclusion, we found enhanced expression of the AT1 receptor and exaggerated response to ANG II of the Af-Art in diabetes, which may contribute to the increased prevalence of hypertension in diabetes.
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Affiliation(s)
- Jie Zhang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
| | - Helena Y Qu
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
| | - Jiangping Song
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
| | - Jin Wei
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
| | - Shan Jiang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
| | - Lei Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
| | - Liqing Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
| | | | - Ruisheng Liu
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa, Florida; and
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Jacobsen JCB, Sorensen CM. Influence of Connexin40 on the renal myogenic response in murine afferent arterioles. Physiol Rep 2015; 3:3/5/e12416. [PMID: 26009638 PMCID: PMC4463840 DOI: 10.14814/phy2.12416] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Renal autoregulation consists of two main mechanisms; the myogenic response and the tubuloglomerular feedback mechanism (TGF). Increases in renal perfusion pressure activate both mechanisms causing a reduction in diameter of the afferent arteriole (AA) resulting in stabilization of the glomerular pressure. It has previously been shown that connexin-40 (Cx40) is essential in the renal autoregulation and mediates the TGF mechanism. The aim of this study was to characterize the myogenic properties of the AA in wild-type and connexin-40 knockout (Cx40KO) mice using both in situ diameter measurements and modeling. We hypothesized that absence of Cx40 would not per se affect myogenic properties as Cx40 is expressed primarily in the endothelium and as the myogenic response is known to be present also in isolated, endothelium-denuded vessels. Methods used were the isolated perfused juxtamedullary nephron preparation to allow diameter measurements of the AA. A simple mathematical model of the myogenic response based on experimental parameters was implemented. Our findings show that the myogenic response is completely preserved in the AA of the Cx40KO and if anything, the stress sensitivity of the smooth muscle cell in the vascular wall is increased rather than reduced as compared to the WT. These findings are compatible with the view of the myogenic response being primarily a local response to the local transmural pressure.
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Affiliation(s)
- Jens Christian B Jacobsen
- Department of Biomedical Sciences, Division of Renal and Vascular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Charlotte M Sorensen
- Department of Biomedical Sciences, Division of Renal and Vascular Physiology, University of Copenhagen, Copenhagen, Denmark
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5
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Gerl M, Vöckl J, Kurt B, van Veen TAB, Kurtz A, Wagner C. Inducible deletion of connexin 40 in adult mice causes hypertension and disrupts pressure control of renin secretion. Kidney Int 2015; 87:557-63. [PMID: 25229336 DOI: 10.1038/ki.2014.303] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 07/17/2014] [Accepted: 07/24/2014] [Indexed: 11/09/2022]
Abstract
Genetic loss-of-function defects of connexin 40 in renal juxtaglomerular cells are associated with renin-dependent hypertension. The dysregulation of renin secretion results from an intrarenal displacement of renin cells and an interruption of the negative feedback control of renin secretion by blood pressure. It is unknown whether this phenotype is secondary to developmental defects of juxtaglomerular renin cells due to connexin 40 malfunction, or whether acute functional defects of connexin 40 in the normal adult kidney can also lead to a similar dysregulation of renin secretion and hypertension. To address this question, we generated mice with an inducible deletion of connexin 40 in the adult kidney by crossing connexin 40-floxed mice with mice harboring a ubiquitously expressed tamoxifen-inducible Cre recombinase. Tamoxifen treatment in these mice strongly reduced connexin 40 mRNA and protein expression in the kidneys. These mice displayed persistent hypertension with renin expression shifted from the media layer of afferent arterioles to juxtaglomerular periglomerular cells. Control of renin secretion by the perfusion pressure was abolished in vitro, whereas in vivo plasma renin concentrations were increased. Thus, interruption of the connexin 40 gene in the adult kidney produced very similar changes in the renin system as had embryonic deletion. Hence, impairments of connexin 40 function in the normal adult kidney can cause renin-dependent hypertension.
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Affiliation(s)
- Melanie Gerl
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Josef Vöckl
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Birgül Kurt
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Toon A B van Veen
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Armin Kurtz
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Charlotte Wagner
- Department of Physiology, University of Regensburg, Regensburg, Germany
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Hills CE, Price GW, Squires PE. Mind the gap: connexins and cell-cell communication in the diabetic kidney. Diabetologia 2015; 58:233-41. [PMID: 25358446 DOI: 10.1007/s00125-014-3427-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/25/2014] [Indexed: 10/24/2022]
Abstract
Connexins, assembled as a hexameric connexon, form a transmembrane hemichannel that provides a conduit for paracrine signalling of small molecules and ions to regulate the activity and function of adjacent cells. When hemichannels align and associate with similar channels on opposing cells, they form a continuous aqueous pore or gap junction, allowing the direct transmission of metabolic and electrical signals between coupled cells. Regulation of gap junction synthesis and channel activity is critical for cell function, and a number of diseases can be attributed to changes in the expression/function of these important proteins. Diabetic nephropathy is associated with several complex metabolic and inflammatory responses characterised by defects at the molecular, cellular and tissue level. In both type 1 and type 2 diabetes, glycaemic injury of the kidney is the leading cause of end-stage renal failure, a consequence of multiple aetiologies, including increased deposition of extracellular matrix, glomerular hyperfiltration, albuminuria and tubulointerstitial fibrosis. In diabetic nephropathy, loss of connexin mediated cell-cell communication within the nephron may represent an early sign of disease; however, our current knowledge of the role of connexins in the diabetic kidney is sparse. This review highlights recent evidence demonstrating that maintenance of connexin-mediated cell-cell communication could benefit region-specific renal function in diabetic nephropathy and suggests that these proteins should be viewed as a tantalising novel target for therapeutic intervention.
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Affiliation(s)
- Claire E Hills
- School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK,
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7
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Kurtz A. Connexins, renin cell displacement and hypertension. Curr Opin Pharmacol 2014; 21:1-6. [PMID: 25483714 DOI: 10.1016/j.coph.2014.11.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 11/25/2014] [Accepted: 11/25/2014] [Indexed: 10/24/2022]
Abstract
Vascular gap junctions formed by specific connexins proteins Cx37, 40, 43 and 45 are important for proper vascular function. This review outlines that defects of the connexin 40 protein leads to hypertension because of dysfunction of renin secreting cells of the kidney. Thus defects of Cx40 but not of other vascular connexins blunt the negative feedback control of renin secretion by the blood pressure, and moreover, lead to a shift of renin expression from the juxtaglomerular vessels walls into the periglomerular interstitium. Evidence exists to indicate that those findings which were primarily obtained with mice are also relevant for humans.
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Affiliation(s)
- Armin Kurtz
- Institute of Physiology, University of Regensburg, Germany.
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8
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Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
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Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
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9
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Nf1 loss and Ras hyperactivation in oligodendrocytes induce NOS-driven defects in myelin and vasculature. Cell Rep 2013; 4:1197-212. [PMID: 24035394 PMCID: PMC3982616 DOI: 10.1016/j.celrep.2013.08.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 06/26/2013] [Accepted: 08/02/2013] [Indexed: 01/05/2023] Open
Abstract
Patients with neurofibromatosis type 1 (NF1) and Costello syndrome Rasopathy have behavioral deficits. In NF1 patients, these may correlate with white matter enlargement and aberrant myelin. To model these features, we induced Nf1 loss or HRas hyperactivation in mouse oligodendrocytes. Enlarged brain white matter tracts correlated with myelin decompaction, downregulation of claudin-11, and mislocalization of connexin-32. Surprisingly, non-cell-autonomous defects in perivascular astrocytes and the blood-brain barrier (BBB) developed, implicating a soluble mediator. Nitric oxide (NO) can disrupt tight junctions and gap junctions, and NO and NO synthases (NOS1–NOS3) were upregulated in mutant white matter. Treating mice with the NOS inhibitor NG-nitro-L-arginine methyl ester or the antioxidant N-acetyl cysteine corrected cellular phenotypes. CNP-HRasG12V mice also displayed locomotor hyperactivity, which could be rescued by antioxidant treatment. We conclude that Nf1/Ras regulates oligodendrocyte NOS and that dysregulated NO signaling in oligodendrocytes can alter the surrounding vasculature. The data suggest that anti-oxidants may improve some behavioral deficits in Rasopathy patients.
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Abstract
In the renal vasculature of humans, rats, and mice, at least four isoforms of Cx, Cxs 37, 40, 43, and 45 are expressed. In the ECs, Cx40 is the predominantly expressed Cx, whereas Cx45 is suggested to be expressed in the VSMCs. The preglomerular vasculature has a higher expression of Cxs than the postglomerular vasculature. Cxs form gap junctions between neighboring cells, and as in other organ systems, the major function of Cxs in the kidney appears to be mediation of intercellular communication. Cxs may also form hemichannels that allow cellular secretion of signaling molecules like ATP, and thereby mediate paracrine signaling. Renal Cxs facilitate vascular conduction, juxtaglomerlar apparatus calcium signaling, and enable ECs and VSMCs to communicate. Thus, current research suggests multiple roles for Cxs in important regulatory mechanisms within the kidney, including the renin-angiotensin system, TGF, and salt and water homeostasis. Interestingly, changes in the activity of the renin-angiotensin system or changes in blood pressure seem to affect the expression of the renal vascular Cxs. At the systemic level, renal Cxs may be involved in blood pressure regulation, and possibly in the pathogenesis of hypertension and diabetes.
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Affiliation(s)
- Charlotte Mehlin Sorensen
- Division of Renal and Cardiovascular Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Hills CE, Siamantouras E, Smith SW, Cockwell P, Liu KK, Squires PE. TGFβ modulates cell-to-cell communication in early epithelial-to-mesenchymal transition. Diabetologia 2012; 55:812-24. [PMID: 22215279 DOI: 10.1007/s00125-011-2409-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 11/10/2011] [Indexed: 10/14/2022]
Abstract
AIMS/HYPOTHESIS A key pathology in diabetic nephropathy is tubulointerstitial fibrosis. The condition is characterised by increased deposition of the extracellular matrix, fibrotic scar formation and declining renal function, with the prosclerotic cytokine TGF-β1 mediating many of these catastrophic changes. Here we investigated whether TGF-β1-induced epithelial-to-mesenchymal transition (EMT) plays a role in alterations in cell adhesion, cell coupling and cell communication in the human renal proximal tubule. METHODS Whole-cell and cell compartment abundance of E-cadherin, N-cadherin, snail, vimentin, β-catenin and connexin-43 was determined in human kidney cell line (HK)2 and human proximal tubule cells with or without TGF-β1, using western blotting and immunocytochemistry, followed by quantification by densitometry. The contribution of connexin-43 in proximal tubule cell communication was quantified using small interfering RNA knockdown, while dye-transfer was used to assess gap junctional intercellular communication (GJIC). Functional tethering was assessed by single-cell force spectroscopy with or without TGF-β1, or by immunoneutralisation of cadherin ligation. RESULTS High glucose (25 mmol/l) increased the secretion of TGF-β1 from HK2 cells. Analysis confirmed early TGF-β1-induced morphological and phenotypical changes of EMT, with altered levels of adhesion and adherens junction proteins. These changes correlated with impaired cell adhesion and decreased tethering between coupled cells. Impaired E-cadherin-mediated adhesion reduced connexin-43 production and GJIC, these effects being mimicked by neutralisation of E-cadherin ligation. Upregulation of N-cadherin failed to restore adhesion or connexin-43-mediated GJIC. CONCLUSIONS/INTERPRETATION We provide compelling evidence that TGF-β1-induced EMT instigates a loss of E-cadherin, cell adhesion and ultimately of connexin-mediated cell communication in the proximal tubule under diabetic conditions; these changes occur ahead of overt signs of renal damage.
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Affiliation(s)
- C E Hills
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
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12
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Becker DL, Thrasivoulou C, Phillips ARJ. Connexins in wound healing; perspectives in diabetic patients. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:2068-75. [PMID: 22155211 DOI: 10.1016/j.bbamem.2011.11.017] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 11/07/2011] [Accepted: 11/18/2011] [Indexed: 11/19/2022]
Abstract
Skin lesions are common events and we have evolved to rapidly heal them in order to maintain homeostasis and prevent infection and sepsis. Most acute wounds heal without issue, but as we get older our bodies become compromised by poor blood circulation and conditions such as diabetes, leading to slower healing. This can result in stalled or hard-to-heal chronic wounds. Currently about 2% of the Western population develop a chronic wound and this figure will rise as the population ages and diabetes becomes more prevalent [1]. Patient morbidity and quality of life are profoundly altered by chronic wounds [2]. Unfortunately a significant proportion of these chronic wounds fail to respond to conventional treatment and can result in amputation of the lower limb. Life quality and expectancy following amputation is severely reduced. These hard to heal wounds also represent a growing economic burden on Western society with published estimates of costs to healthcare services in the region of $25B annually [3]. There exists a growing need for specific and effective therapeutic agents to improve healing in these wounds. In recent years the gap junction protein Cx43 has been shown to play a pivotal role early on in the acute wound healing process at a number of different levels [4-7]. Conversely, abnormal expression of Cx43 in wound edge keratinocytes was shown to underlie the poor rate of healing in diabetic rats, and targeting its expression with an antisense gel restored normal healing rates [8]. The presence of Cx43 in the wound edge keratinocytes of human chronic wounds has also been reported [9]. Abnormal Cx43 biology may underlie the poor healing of human chronic wounds and be amenable therapeutic intervention [7]. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- David L Becker
- Department of Cell and Developmental Biology, University College, London, WC1E 6BT, UK.
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13
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Looft-Wilson RC, Billaud M, Johnstone SR, Straub AC, Isakson BE. Interaction between nitric oxide signaling and gap junctions: effects on vascular function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1895-902. [PMID: 21835160 DOI: 10.1016/j.bbamem.2011.07.031] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 07/14/2011] [Accepted: 07/19/2011] [Indexed: 02/07/2023]
Abstract
Nitric oxide signaling, through eNOS (or possibly nNOS), and gap junction communication are essential for normal vascular function. While each component controls specific aspects of vascular function, there is substantial evidence for cross-talk between nitric oxide signaling and the gap junction proteins (connexins), and more recently, protein-protein association between eNOS and connexins. This review will examine the evidence for interaction between these pathways in normal and diseased arteries, highlight the questions that remain about the mechanisms of their interaction, and explore the possible interaction between nitric oxide signaling and the newly discovered pannexin channels. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- R C Looft-Wilson
- Department of Kinesiology and Health Sciences, College of William and Mary, Williamsburg, VA 23187, USA
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14
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Belkina LM, Terekhina OL, Smirnova EA, Usacheva MA, Kruglov SV, Saltykova VA. Effect of Acute Alloxan Diabetes on Ischemic and Reperfusion Arrhythmias in Rats with Different Activity of Nitric Oxide System. Bull Exp Biol Med 2011; 150:299-303. [DOI: 10.1007/s10517-011-1127-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Down-regulation of connexin43 gap junction by serum deprivation in human endothelial cells was improved by (-)-Epigallocatechin gallate via ERK MAP kinase pathway. Biochem Biophys Res Commun 2010; 404:217-22. [PMID: 21110950 DOI: 10.1016/j.bbrc.2010.11.096] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 11/22/2010] [Indexed: 11/23/2022]
Abstract
Intercellular communication through gap junctions (GJIC) plays an essential role in maintaining the functional integrity of vascular endothelium. Despite emerging evidence suggests that (-)-Epigallocatechin gallate (EGCG) may improve endothelial function. However, its effect on Cx43 gap junction in endothelial cells remains unexplored. Here we investigated the effect of EGCG on connexin43 (Cx43) gap junction in endothelial cells. The levels of Cx43 protein in human umbilical vein endothelial cells (HUVECs) cultured under serum-deprivation 48 h decreased about 50%, accompanied by decreased GJIC. This reduction can be reversed by treatments with EGCG. In addition, EGCG activated ERK, P38, and JNK mitogen-activated protein kinases (MAPKs), which were supposed to participate in the regulation of Cx43. A MEK inhibitor PD98059, but not SB203580 (a p38 kinase inhibitor) or SP600125 (a JNK kinase inhibitor), abolished the effects of EGCG on Cx43 expression and GJIC. Moreover, although both Akt and eNOS phosphorylation were time-dependently augmented by EGCG, neither PI3K inhibitor LY294002 nor eNOS inhibitor L-NAME blocked the effects of EGCG on Cx43 gap junctions. Thus, EGCG attenuated Cx43 down-regulation and impaired GJIC induced by serum deprivation, ERK MAPK Signal transduction pathway appears to be involved in these processes.
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Hanner F, Sorensen CM, Holstein-Rathlou NH, Peti-Peterdi J. Connexins and the kidney. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1143-55. [PMID: 20164205 DOI: 10.1152/ajpregu.00808.2009] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Connexins (Cxs) are widely-expressed proteins that form gap junctions in most organs, including the kidney. In the renal vasculature, Cx37, Cx40, Cx43, and Cx45 are expressed, with predominant expression of Cx40 in the endothelial cells and Cx45 in the vascular smooth muscle cells. In the tubules, there is morphological evidence for the presence of gap junction plaques only in the proximal tubules. In the distal nephron, Cx30, Cx30.3, and Cx37 are expressed, but it is not known whether they form gap junctions connecting neighboring cells or whether they primarily act as hemichannels. As in other systems, the major function of Cxs in the kidney appears to be intercellular communication, although they may also form hemichannels that allow cellular secretion of large signaling molecules. Renal Cxs facilitate vascular conduction, juxtaglomerular apparatus calcium signaling, and tubular purinergic signaling. Accordingly, current evidence points to roles for these Cxs in several important regulatory mechanisms in the kidney, including the renin angiotensin system, tubuloglomerular feedback, and salt and water reabsorption. At the systemic level, renal Cxs may help regulate blood pressure and may be involved in hypertension and diabetes.
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Affiliation(s)
- Fiona Hanner
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo St., Los Angeles, CA 90033, USA
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Navar LG, Arendshorst WJ, Pallone TL, Inscho EW, Imig JD, Bell PD. The Renal Microcirculation. Compr Physiol 2008. [DOI: 10.1002/cphy.cp020413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Navar LG, Arendshorst WJ, Pallone TL, Inscho EW, Imig JD, Bell PD. The Renal Microcirculation. Microcirculation 2008. [DOI: 10.1016/b978-0-12-374530-9.00015-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Abstract
Connexins form intercellular channels that span two plasma membranes and directly couple the cytoplasm of adjacent cells. This morphological contact enables the exchange of ions, second messengers, and metabolites, which act to regulate several biological functions. This review focuses on the significance of connexins in the renal circulation. Cells of the renal vasculature are coupled and express connexins in a vessel and cell-specific pattern. This finding indicates that renal connexins likely play an important role in renal autoregulatory mechanisms (Bayliss effect, tubuloglomerular feedback) and in the control of vasomotor responses. The described coupling of endothelial and vascular smooth muscle cells in the afferent arterioles may also contribute to the communication of neighboring nephrons, called 'nephron coupling.' Furthermore, deletion of the Cx40 and Cx43 genes results in an altered functional behavior of the renin-producing cells, suggesting involvement of these connexin isoforms in the regulation of renin secretion and synthesis. In addition, this review discusses the role of renal connexin expression in the pathogenesis of hypertension or diabetes.
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Affiliation(s)
- C Wagner
- Physiologisches Institut der Universität Regensburg, Regensburg, Germany.
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Zhang J, Kawashima S, Yokoyama M, Huang P, Hill CE. Protective effect of endothelial nitric oxide synthase against induction of chemically-induced diabetes in mice. Nitric Oxide 2007; 17:69-74. [PMID: 17658282 DOI: 10.1016/j.niox.2007.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Revised: 06/08/2007] [Accepted: 06/12/2007] [Indexed: 11/23/2022]
Abstract
Since activation of endothelial nitric oxide synthase has been shown to exert protective effects against the metabolic syndrome, while endothelial nitric oxide synthase knockout mice develop hyperinsulinemia and glucose intolerance, we hypothesised that endothelial nitric oxide might play a protective role against induction of diabetes. The role of endothelial nitric oxide in the development of chemically-induced diabetes has been determined using mice in which the bioavailability of endothelial nitric oxide was either increased, through upregulation of endothelial nitric oxide synthase, or absent, through deletion of endothelial nitric oxide synthase gene. Diabetes was induced intraperitoneally with either a single dose of alloxan, streptozotocin, or multiple low doses of streptozotocin and blood glucose monitored twice a week. The role of cyclic guanosine monophosphate was investigated in wildtype mice by treatment with the phosphodiesterase inhibitor, tadalafil, during diabetes induction. Results showed that the incidence of diabetes was markedly decreased in mice overexpressing endothelial nitric oxide synthase, compared to wildtype or endothelial nitric oxide synthase knockout mice, regardless of the method of diabetes induction. Under normal physiological conditions, or during diabetes induction with alloxan or multiple low doses of streptozotocin, blood glucose was significantly lower in mice overexpressing endothelial nitric oxide synthase compared to wildtype or knockout mice. Treatment with tadalafil had no effect on the incidence or severity of diabetes in wildtype mice. We conclude that upregulation of endothelial nitric oxide synthase exerts a protective action against diabetes induction through a direct effect of nitric oxide, independently of cyclic guanosine monophosphate.
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Affiliation(s)
- J Zhang
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 2602, Australia
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