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Bahadoran Z, Mirmiran P, Kashfi K, Ghasemi A. Vascular nitric oxide resistance in type 2 diabetes. Cell Death Dis 2023; 14:410. [PMID: 37433795 DOI: 10.1038/s41419-023-05935-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 06/18/2023] [Accepted: 06/28/2023] [Indexed: 07/13/2023]
Abstract
Vascular nitric oxide (NO•) resistance, manifested by an impaired vasodilator function of NO• in both the macro- and microvessels, is a common state in type 2 diabetes (T2D) associated with developing cardiovascular events and death. Here, we summarize experimental and human evidence of vascular NO• resistance in T2D and discuss its underlying mechanisms. Human studies indicate a ~ 13-94% decrease in the endothelium (ET)-dependent vascular smooth muscle (VSM) relaxation and a 6-42% reduced response to NO• donors, i.e., sodium nitroprusside (SNP) and glyceryl trinitrate (GTN), in patients with T2D. A decreased vascular NO• production, NO• inactivation, and impaired responsiveness of VSM to NO• [occurred due to quenching NO• activity, desensitization of its receptor soluble guanylate cyclase (sGC), and/or impairment of its downstream pathway, cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG)] are the known mechanisms underlying the vascular NO• resistance in T2D. Hyperglycemia-induced overproduction of reactive oxygen species (ROS) and vascular insulin resistance are key players in this state. Therefore, upregulating vascular NO• availability, re-sensitizing or bypassing the non-responsive pathways to NO•, and targeting key vascular sources of ROS production may be clinically relevant pharmacological approaches to circumvent T2D-induced vascular NO• resistance.
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Affiliation(s)
- Zahra Bahadoran
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Parvin Mirmiran
- Department of Clinical Nutrition, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Khosrow Kashfi
- Department of Molecular, Cellular, and Biomedical Sciences, Sophie Davis School of Biomedical Education, City University of New York School of Medicine, New York, NY, 10031, USA
| | - Asghar Ghasemi
- Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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2
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Meter D, Racetin A, Vukojević K, Balog M, Ivić V, Zjalić M, Heffer M, Filipović N. A Lack of GD3 Synthase Leads to Impaired Renal Expression of Connexins and Pannexin1 in St8sia1 Knockout Mice. Int J Mol Sci 2022; 23:ijms23116237. [PMID: 35682927 PMCID: PMC9181035 DOI: 10.3390/ijms23116237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 05/28/2022] [Accepted: 05/30/2022] [Indexed: 02/01/2023] Open
Abstract
The aim of this study was to determine the effects of altered ganglioside composition on the expression of Cx37, Cx40, Cx43, Cx45, and Panx1 in different kidney regions of St8sia1 gene knockout mice (St8sia1 KO) lacking the GD3 synthase enzyme. Experiments were performed in twelve male 6-month-old mice: four wild-type (C57BL/6-type, WT) and eight St8sia1 KO mice. After euthanasia, kidney tissue was harvested, embedded in paraffin wax, and processed for immunohistochemistry. The expression of connexins and Panx1 was determined in different regions of the kidney: cortex (CTX.), outer stripe of outer medulla (O.S.), inner stripe of outer medulla (IN.S.), and inner medulla (IN.MED.). We determined significantly lower expression of Cx37, Cx40, Cx45, and Panx1 in different parts of the kidneys of St8sia1 KO mice compared with WT. The most consistent decrease was found in the O.S. where all markers (Cx 37, 40, 45 and Panx1) were disrupted in St8si1 KO mice. In the CTX. region, we observed decrease in the expression of Cx37, Cx45, and Panx1, while reduced expression of Cx37 and Panx1 was more specific to IN.S. The results of the present study suggest that deficiency of GD3 synthase in St8sia1 KO mice leads to disruption of renal Cx expression, which is probably related to alteration of ganglioside composition.
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Affiliation(s)
- Diana Meter
- Department of Rheumatology and Clinical Immunology, University Hospital of Split, Spinčićeva 1, 21000 Split, Croatia;
| | - Anita Racetin
- Laboratory for Early Human Development, Department of Anatomy, Histology and Embryology, University of Split School of Medicine, Šoltanska 2, 21000 Split, Croatia; (A.R.); (K.V.)
| | - Katarina Vukojević
- Laboratory for Early Human Development, Department of Anatomy, Histology and Embryology, University of Split School of Medicine, Šoltanska 2, 21000 Split, Croatia; (A.R.); (K.V.)
- Laboratory for Neurocardiology, Department of Anatomy, Histology and Embryology, University of Split School of Medicine, Šoltanska 2, 21000 Split, Croatia
| | - Marta Balog
- Department of Medical Biology and Genetics, Faculty of Medicine Osijek, Josip Juraj Strossmayer University of Osijek, Huttlerova 4, 31000 Osijek, Croatia; (M.B.); (V.I.); (M.H.)
| | - Vedrana Ivić
- Department of Medical Biology and Genetics, Faculty of Medicine Osijek, Josip Juraj Strossmayer University of Osijek, Huttlerova 4, 31000 Osijek, Croatia; (M.B.); (V.I.); (M.H.)
| | - Milorad Zjalić
- Department of Molecular Medicine and Biotechnology, Faculty of Medicine Rijeka, University of Rijeka, Branchetta brothers 20, 51000 Rijeka, Croatia;
| | - Marija Heffer
- Department of Medical Biology and Genetics, Faculty of Medicine Osijek, Josip Juraj Strossmayer University of Osijek, Huttlerova 4, 31000 Osijek, Croatia; (M.B.); (V.I.); (M.H.)
| | - Natalija Filipović
- Laboratory for Early Human Development, Department of Anatomy, Histology and Embryology, University of Split School of Medicine, Šoltanska 2, 21000 Split, Croatia; (A.R.); (K.V.)
- Correspondence:
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3
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Activation of Cx43 Hemichannels Induces the Generation of Ca 2+ Oscillations in White Adipocytes and Stimulates Lipolysis. Int J Mol Sci 2021; 22:ijms22158095. [PMID: 34360859 PMCID: PMC8347185 DOI: 10.3390/ijms22158095] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 12/11/2022] Open
Abstract
The aim of the study was to investigate the mechanisms of Ca2+ oscillation generation upon activation of connexin-43 and regulation of the lipolysis/lipogenesis balance in white adipocytes through vesicular ATP release. With fluorescence microscopy it was revealed that a decrease in the concentration of extracellular calcium ([Ca2+]ex) results in two types of Ca2+ responses in white adipocytes: Ca2+ oscillations and transient Ca2+ signals. It was found that activation of the connexin half-channels is involved in the generation of Ca2+ oscillations, since the blockers of the connexin hemichannels-carbenoxolone, octanol, proadifen and Gap26-as well as Cx43 gene knockdown led to complete suppression of these signals. The activation of Cx43 in response to the reduction of [Ca2+]ex was confirmed by TIRF microscopy. It was shown that in response to the activation of Cx43, ATP-containing vesicles were released from the adipocytes. This process was suppressed by knockdown of the Cx43 gene and by bafilomycin A1, an inhibitor of vacuolar ATPase. At the level of intracellular signaling, the generation of Ca2+ oscillations in white adipocytes in response to a decrease in [Ca2+]ex occurred due to the mobilization of the Ca2+ ions from the thapsigargin-sensitive Ca2+ pool of IP3R as a result of activation of the purinergic P2Y1 receptors and phosphoinositide signaling pathway. After activation of Cx43 and generation of the Ca2+ oscillations, changes in the expression levels of key genes and their encoding proteins involved in the regulation of lipolysis were observed in white adipocytes. This effect was accompanied by a decrease in the number of adipocytes containing lipid droplets, while inhibition or knockdown of Cx43 led to inhibition of lipolysis and accumulation of lipid droplets. In this study, we investigated the mechanism of Ca2+ oscillation generation in white adipocytes in response to a decrease in the concentration of Ca2+ ions in the external environment and established an interplay between periodic Ca2+ modes and the regulation of the lipolysis/lipogenesis balance.
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Saadati M, Jamali Y. The effects of beta-cell mass and function, intercellular coupling, and islet synchrony on [Formula: see text] dynamics. Sci Rep 2021; 11:10268. [PMID: 33986325 PMCID: PMC8119479 DOI: 10.1038/s41598-021-89333-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 04/26/2021] [Indexed: 11/30/2022] Open
Abstract
Type 2 diabetes (T2D) is a challenging metabolic disorder characterized by a substantial loss of [Formula: see text]-cell mass and alteration of [Formula: see text]-cell function in the islets of Langerhans, disrupting insulin secretion and glucose homeostasis. The mechanisms for deficiency in [Formula: see text]-cell mass and function during the hyperglycemia development and T2D pathogenesis are complex. To study the relative contribution of [Formula: see text]-cell mass to [Formula: see text]-cell function in T2D, we make use of a comprehensive electrophysiological model of human [Formula: see text]-cell clusters. We find that defect in [Formula: see text]-cell mass causes a functional decline in single [Formula: see text]-cell, impairment in intra-islet synchrony, and changes in the form of oscillatory patterns of membrane potential and intracellular [Formula: see text] concentration, which can lead to changes in insulin secretion dynamics and in insulin levels. The model demonstrates a good correspondence between suppression of synchronizing electrical activity and published experimental measurements. We then compare the role of gap junction-mediated electrical coupling with both [Formula: see text]-cell synchronization and metabolic coupling in the behavior of [Formula: see text] concentration dynamics within human islets. Our results indicate that inter-[Formula: see text]-cellular electrical coupling depicts a more important factor in shaping the physiological regulation of islet function and in human T2D. We further predict that varying the whole-cell conductance of delayed rectifier [Formula: see text] channels modifies oscillatory activity patterns of [Formula: see text]-cell population lacking intercellular coupling, which significantly affect [Formula: see text] concentration and insulin secretion.
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Affiliation(s)
- Maryam Saadati
- Biomathematics Laboratory, Department of Applied Mathematics, School of Mathematical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Yousef Jamali
- Biomathematics Laboratory, Department of Applied Mathematics, School of Mathematical Sciences, Tarbiat Modares University, Tehran, Iran
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5
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Haep N, Florentino RM, Squires JE, Bell A, Soto-Gutierrez A. The Inside-Out of End-Stage Liver Disease: Hepatocytes are the Keystone. Semin Liver Dis 2021; 41:213-224. [PMID: 33992030 PMCID: PMC8996333 DOI: 10.1055/s-0041-1725023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Chronic liver injury results in cirrhosis and end-stage liver disease (ESLD) which represents a leading cause of death worldwide, affecting people in their most productive years of life. Medical therapy can extend life, but the only definitive treatment is liver transplantation (LT). However, LT remains limited by access to quality donor organs and suboptimal long-term outcomes. The degeneration from healthy-functioning livers to cirrhosis and ESLD involves a dynamic process of hepatocyte damage, diminished hepatic function, and adaptation. However, the mechanisms responsible for deterioration of hepatocyte function and ultimately hepatic failure in man are poorly understood. We review the current understanding of cirrhosis and ESLD as a dynamic process and outline the current mechanisms associated with the development of hepatic failure from the clinical manifestations to energy adaptations, regeneration, and regulation of nuclear transcription factors. A new generation of therapeutics could target stabilization of hepatocyte differentiation and function to avoid the need for transplantation in patients with cirrhosis and ESLD.
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Affiliation(s)
- Nils Haep
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | | | - James E. Squires
- Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Children’s Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania,Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Aaron Bell
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania,Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Alejandro Soto-Gutierrez
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania,Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania
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Thakur V, Alcoreza N, Delgado M, Joddar B, Chattopadhyay M. Cardioprotective Effect of Glycyrrhizin on Myocardial Remodeling in Diabetic Rats. Biomolecules 2021; 11:569. [PMID: 33924458 PMCID: PMC8069839 DOI: 10.3390/biom11040569] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 01/31/2023] Open
Abstract
Myocardial fibrosis is one of the major complications of long-term diabetes. Hyperglycemia induced cardiomyocyte atrophy is a frequent pathophysiological indicator of diabetic heart. The objective of this study was to investigate the cardioprotective effect of glycyrrhizin (GLC) on myocardial damage in diabetic rats and assess the anti-inflammatory and anti-fibrotic effect of GLC. Our study demonstrates that hyperglycemia can elevate cardiac atrophy in diabetic animals. Type 2 diabetic fatty and the lean control rats were evaluated for cardiac damage and inflammation at 8-12 weeks after the development of diabetes. Western blot and immunohistochemical studies revealed that gap junction protein connexin-43 (CX43), cardiac injury marker troponin I, cardiac muscle specific voltage gated sodium channel NaV1.5 were significantly altered in the diabetic heart. Furthermore, oxidative stress mediator receptor for advanced glycation end-products (RAGE), as well as inflammatory mediator phospho-p38 MAPK and chemokine receptor CXCR4 were increased in the diabetic heart whereas the expression of nuclear factor erythroid-2-related factor 2 (Nrf2), the antioxidant proteins that protect against oxidative damage was reduced. We also observed an increase in the expression of the pleiotropic cytokine, transforming growth factor beta (TGF-β) in the diabetic heart. GLC treatment exhibited a decrease in the expression of phospho-p38 MAPK, RAGE, NaV1.5 and TGF-β and it also altered the expression of CX43, CXCR4, Nrf2 and troponin I. These observations suggest that GLC possesses cardioprotective effects in diabetic cardiac atrophy and that these effects could be mediated through activation of Nrf2 and inhibition of CXCR4/SDF1 as well as TGF-β/p38MAPK signaling pathway.
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Affiliation(s)
- Vikram Thakur
- Center of Emphasis in Diabetes and Metabolism, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA;
| | - Narah Alcoreza
- Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA;
| | - Monica Delgado
- Inspired Materials & Stem-Cell Based Tissue Engineering Laboratory (IMSTEL), Department of Metallurgical, Materials and Biomedical Engineering, The University of Texas at El Paso, El Paso, TX 79968, USA; (M.D.); (B.J.)
| | - Binata Joddar
- Inspired Materials & Stem-Cell Based Tissue Engineering Laboratory (IMSTEL), Department of Metallurgical, Materials and Biomedical Engineering, The University of Texas at El Paso, El Paso, TX 79968, USA; (M.D.); (B.J.)
| | - Munmun Chattopadhyay
- Center of Emphasis in Diabetes and Metabolism, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA;
- Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA;
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7
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Nugent L, Ofori-Frimpong B, Martin PE, Green CR, Wright CS. Cx31.1 expression is modulated in HaCaT cells exposed to UV-induced damage and scrape-wounding. J Cell Physiol 2020; 236:911-920. [PMID: 32592185 DOI: 10.1002/jcp.29901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/22/2020] [Accepted: 06/13/2020] [Indexed: 02/02/2023]
Abstract
Connexin31.1 (Cx31.1) is a gap junction protein associated with apoptosis. In the skin, apoptosis is modulated by diabetes. A HaCaT skin model investigated whether normal (NGI) and high glucose and insulin (HGI; diabetic) conditions altered Cx31.1 expression, and if these were apoptosis linked. Cx31.1 was found in HaCaT and HeLa Ohio cells, with HaCaT Cx31.1 protein increased in HGI conditions, and around apoptotic cells. HeLa Cx31.1 channels were noncommunicative. Post scrape-wounding, Cx31.1 increased at wound edges. Caspase 3/7 in scrape-wounds media (containing cells) elevated in HGI. UV exposure raised Cx31.1, and caspase 3/7, in NGI and HGI. UV reduced cell viability in NGI cells, although not significantly in HGI. Cx31.1 is modulated during HaCaT cell wound closure, and associated with 'diabetic' conditions. Cx31.1 expression matched apoptosis levels, higher in HGI cultures. Cx31.1 is noncommunicating, modulated after wounding, linked to apoptosis, and may be associated with tissue turn-over around diabetic wounds.
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Affiliation(s)
- Louise Nugent
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Boatemaa Ofori-Frimpong
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Patricia E Martin
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Colin R Green
- Department of Opthamology, School of Medicine, University of Auckland, Auckland, New Zealand
| | - Catherine S Wright
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
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Eftekhari A, Vahed SZ, Kavetskyy T, Rameshrad M, Jafari S, Chodari L, Hosseiniyan SM, Derakhshankhah H, Ahmadian E, Ardalan M. Cell junction proteins: Crossing the glomerular filtration barrier in diabetic nephropathy. Int J Biol Macromol 2020; 148:475-482. [PMID: 31962072 DOI: 10.1016/j.ijbiomac.2020.01.168] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/17/2020] [Accepted: 01/17/2020] [Indexed: 12/20/2022]
Abstract
Diabetic nephropathy as a deleterious complication of diabetes mellitus and an important cause of end-stage renal failure is characterized by changes in the molecular and cellular levels. Cell-cell communication via the gap and tight junctions are involved in the pathogenesis of diseases such as diabetes and kidney failure. Studying cell junctions including gap junctions, tight junctions, and anchoring junctions within the nephron can be used as an early sign of diabetic nephropathy. Furthermore, cell junctions may be an upcoming target by pharmacological methods to improve treatments of diabetic nephropathy and pave the way to introduce promising therapeutic strategies based on cell-cell communications effects and its translation into clinical studies for the treatment of diabetic nephropathy.
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Affiliation(s)
- Aziz Eftekhari
- Pharmacology and Toxicology Department, Maragheh University of Medical Sciences, Maragheh, Iran
| | | | - Taras Kavetskyy
- Drohobych Ivan Franko State Pedagogical University, Drohobych, Ukraine; The John Paul II Catholic University of Lublin, Lublin, Poland
| | - Maryam Rameshrad
- Natural Products and Medicinal Plants Research Center, North Khorasan University of Medical Sciences, Bojnurd, Iran
| | - Samira Jafari
- Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Leila Chodari
- Physiology Department, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | | | - Hossein Derakhshankhah
- Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Elham Ahmadian
- Kidney Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Students Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
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PUFAs supplementation affects the renal expression of pannexin 1 and connexins in diabetic kidney of rats. Histochem Cell Biol 2019; 153:165-175. [PMID: 31858211 DOI: 10.1007/s00418-019-01838-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2019] [Indexed: 12/26/2022]
Abstract
In diabetic nephropathy (DN), intercellular communication is disrupted. Connexins (Cx) have a crucial role in that process. Dietary ratios and supplementation with polyunsaturated fatty acids (PUFAs) can alleviate diabetic complications and cause alterations in Cx levels. Although pannexins (Panx) share similarities with members of the Cx family, their function in diabetic nephropathy has still not been fully determined. We studied the influence of PUFA supplementation on the immunoexpression of Px1 and Cx family members in diabetic kidneys of rats. Four groups of rats in experimental DM1 model were supplemented with different dietary n-6/n-3 ratios; ≈7 in control (C) and diabetic groups (STZ), ≈ 60 in the STZ + N6 group and ≈ 1 (containing 16% EPA and 19% DHA) in the STZ + N3 group. Immunoexpression of Cx40, Cx43, Cx45 and Panx1 was evaluated in the renal tissue of diabetic rats using immunohistochemistry. Diabetes significantly decreased the protein expression of Cx40 and Cx43 and increased Panx1 protein expression in the renal cortex (p < 0.05-p < 0.01). There was a significant impact of diet on Cx and Panx1 immunoexpression. Dietary supplementation with a high n-6/n-3 ratio downregulated the protein expression of Cx45 and Panx1 in diabetic rats (p < 0.05-p < 0.01), while Cx43 immunoexpression was increased in diabetic rats fed with high and low n-6/n-3 ratios (p < 0.01-p < 0.001). Hyperglycaemic conditions in DN interfere with cell-to-cell communication and disturb the connection between cells and their immediate environment due to variations in connexin and pannexin immunoexpression. These variations can be regulated by PUFA dietary intake, suggesting their beneficial effect and possible therapeutic option.
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10
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Type 1 diabetes mellitus induces structural changes and molecular remodelling in the rat kidney. Mol Cell Biochem 2018; 449:9-25. [DOI: 10.1007/s11010-018-3338-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Accepted: 02/17/2018] [Indexed: 12/24/2022]
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Faniku C, O'Shaughnessy E, Lorraine C, Johnstone SR, Graham A, Greenhough S, Martin PEM. The Connexin Mimetic Peptide Gap27 and Cx43-Knockdown Reveal Differential Roles for Connexin43 in Wound Closure Events in Skin Model Systems. Int J Mol Sci 2018; 19:ijms19020604. [PMID: 29463027 PMCID: PMC5855826 DOI: 10.3390/ijms19020604] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 02/07/2018] [Accepted: 02/09/2018] [Indexed: 12/23/2022] Open
Abstract
In the epidermis, remodelling of Connexin43 is a key event in wound closure. However, controversy between the role of connexin channel and non-channel functions exist. We compared the impact of SiRNA targeted to Connexin43 and the connexin mimetic peptide Gap27 on scrape wound closure rates and hemichannel signalling in adult keratinocytes (AK) and fibroblasts sourced from juvenile foreskin (JFF), human neonatal fibroblasts (HNDF) and adult dermal tissue (ADF). The impact of these agents, following 24 h exposure, on GJA1 (encoding Connexin43), Ki67 and TGF-β1 gene expression, and Connexin43 and pSmad3 protein expression levels, were examined by qPCR and Western Blot respectively. In all cell types Gap27 (100 nM–100 μM) attenuated hemichannel activity. In AK and JFF cells, Gap27 (100 nM–100 μM) enhanced scrape wound closure rates by ~50% but did not influence movement in HNDF or ADF cells. In both JF and AK cells, exposure to Gap27 for 24 h reduced the level of Cx43 protein expression but did not affect the level in ADF and HNDF cells. Connexin43-SiRNA enhanced scrape wound closure in all the cell types under investigation. In HDNF and ADF, Connexin43-SiRNA enhanced cell proliferation rates, with enhanced proliferation also observed following exposure of HDNF to Gap27. By contrast, in JFF and AK cells no changes in proliferation occurred. In JFF cells, Connexin43-SiRNA enhanced TGF-β1 levels and in JFF and ADF cells both Connexin43-SiRNA and Gap27 enhanced pSmad3 protein expression levels. We conclude that Connexin43 signalling plays an important role in cell migration in keratinocytes and foreskin derived fibroblasts, however, different pathways are evoked and in dermal derived adult and neonatal fibroblasts, inhibition of Connexin43 signalling plays a more significant role in regulating cell proliferation than cell migration.
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Affiliation(s)
- Chrysovalantou Faniku
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Erin O'Shaughnessy
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Claire Lorraine
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Scott R Johnstone
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, P.O. Box 801394, Charlottesville, VA 22908, USA.
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, UK.
| | - Annette Graham
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Sebastian Greenhough
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Patricia E M Martin
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
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12
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Khan D, Moffet CR, Flatt PR, Kelly C. Role of islet peptides in beta cell regulation and type 2 diabetes therapy. Peptides 2018; 100:212-218. [PMID: 29412821 DOI: 10.1016/j.peptides.2017.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/22/2017] [Accepted: 11/22/2017] [Indexed: 12/25/2022]
Abstract
The endocrine pancreas is composed of islets of Langerhans, which secrete a variety of peptide hormones critical for the maintenance of glucose homeostasis. Insulin is the primary regulator of glucose and its secretion from beta-cells is tightly regulated in response to physiological demands. Direct cell-cell communication within islets is essential for glucose-induced insulin secretion. Emerging data suggest that islet connectivity is also important in the regulating the release of other islet hormones including glucagon and somatostatin. Autocrine and paracrine signals exerted by secreted peptides within the islet also play a key role. A great deal of attention has focused on classical islet peptides, namely insulin, glucagon and somatostatin. Recently, it has become clear that islets also synthesise and secrete a range of non-classical peptides, which regulate beta-cell function and insulin release. The current review summarises the roles of islet cell connectivity and islet peptide-driven autocrine and paracrine signalling in beta-cell function and survival. The potential to harness the paracrine effects of non-classical islet peptides for the treatment of type 2 diabetes is also briefly discussed.
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Affiliation(s)
- Dawood Khan
- Northern Ireland Centre for Stratified Medicine, Biomedical Sciences Research Institute, University of Ulster, C-TRIC Building, Altnagelvin Area Hospital, Glenshane Road, L/Derry, BT47 6SB, Northern Ireland, UK
| | - Charlotte R Moffet
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Catriona Kelly
- Northern Ireland Centre for Stratified Medicine, Biomedical Sciences Research Institute, University of Ulster, C-TRIC Building, Altnagelvin Area Hospital, Glenshane Road, L/Derry, BT47 6SB, Northern Ireland, UK.
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Chen B, Sun L, Wu X, Ma J. Correlation between connexin and traumatic brain injury in patients. Brain Behav 2017; 7:e00770. [PMID: 28948071 PMCID: PMC5607540 DOI: 10.1002/brb3.770] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 06/08/2017] [Accepted: 06/14/2017] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Identification of molecular alterations of damaged tissue in patients with neurological disorders can provide novel insight and potential therapeutic target for treatment of the diseases. It has been suggested by animal studies that connexins (CXs), a family of gap junction proteins, could contribute to neuronal cell death and associate with neurological deficits during trauma-induced damage. Nevertheless, whether specific CXs are involved in traumatic brain injury (TBI) has remained unexplored in human patients. METHODS In a clinical setting, we performed a correlation study of 131 TBI patients who received brain surgery. CXs (including CX40, CX43, and CX45) were examined in the harvested brain tissues for studying the relationships with the Glasgow Coma Scale scores of the patients. RESULTS Specifically, the protein levels of CX43 (negatively) and CX40 (positively) are associated with the extent of disease severity. Meanwhile, the phosphorylation status of CX43 was strongly associated with the severe TBI patients who contain relatively high kinase activities of PKC (protein kinase C) and MAPK (mitogen-activated protein kinase), two possible activators for CX43 phosphorylation. CONCLUSION These data highlight that a cluster of connexin family gap junction proteins not previously studied in humans is significantly correlated with the disease progression of TBI.
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Affiliation(s)
| | - Liwei Sun
- Tianjin Huanhu Hospital Tianjin China
| | | | - Jun Ma
- School of Public Health Tianjin Medical University Tianjin China
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14
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Vitale ML, Garcia CJ, Akpovi CD, Pelletier RM. Distinctive actions of connexin 46 and connexin 50 in anterior pituitary folliculostellate cells. PLoS One 2017; 12:e0182495. [PMID: 28759642 PMCID: PMC5536325 DOI: 10.1371/journal.pone.0182495] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 07/19/2017] [Indexed: 12/16/2022] Open
Abstract
Folliculostellate cell gap junctions establish a network for the transmission of information within the anterior pituitary. Connexins make up gap junction channels. Changes in connexin (Cx) turnover modify gap junction-mediated intercellular communication. We have reported that cytokines and hormones influence Cx43 turnover and coupling in folliculostellate cells and in the folliculostellate cell line TtT/GF. In addition, the expression of different connexins alters intercellular communication and connexins may have functions besides cell coupling. Here we assessed the expression, turnover and subcellular localization of Cx46 and Cx50 in the anterior pituitary and TtT/GF cells. Then, we assessed the impact of various natural (lactation, annual reproductive cycle, bFGF) and pathological (autoimmune orchitis, diabetes/obesity) conditions associated with altered anterior pituitary hormone secretion on Cx46 and Cx50. Anterior pituitary Cx46 and Cx50 expression and subcellular distribution were cell-dependent. Cx46 was expressed by folliculostellate, TtT/GF and endocrine cells. In the cytoplasm, Cx46 was chiefly associated with lysosomes. Variously sized Cx46 molecules were recovered exclusively in the TtT/GF cell nuclear fraction. In the nucleus, Cx46 co-localized with Nopp-140, a nucleolar factor involved in rRNA processing. Neither cytoplasmic nor nuclear Cx46 and Cx43 co-localized. Cx50 localized to folliculostellate and TtT/GF cells, and to the walls of blood capillaries, not to endocrine cells. Cx50 was cytoplasmic and associated with the cell membrane, not nuclear. Cx50 did not co-localize with Cx46 but it co-localized in the cytoplasm and co-immunoprecipitated with Cx43. Cx46 and Cx50 responses to various physiological and pathological challenges were different, often opposite. Cx46 and Cx43 expression and phosphorylation profiles differed in the anterior pituitary, whereas Cx50 and Cx43 were similar. The data suggest that Cx46 participates to cellular growth and proliferation and that Cx50, together with Cx43, contributes to folliculostellate cell coupling.
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Affiliation(s)
- María Leiza Vitale
- Département de pathologie et biologie cellulaire, Faculté de Médecine, Université de Montréal, Montreal, Québec, Canada
| | - Christopher J. Garcia
- Département de pathologie et biologie cellulaire, Faculté de Médecine, Université de Montréal, Montreal, Québec, Canada
| | - Casimir D. Akpovi
- Département de pathologie et biologie cellulaire, Faculté de Médecine, Université de Montréal, Montreal, Québec, Canada
| | - R.-Marc Pelletier
- Département de pathologie et biologie cellulaire, Faculté de Médecine, Université de Montréal, Montreal, Québec, Canada
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15
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Roy S, Kim D, Lim R. Cell-cell communication in diabetic retinopathy. Vision Res 2017; 139:115-122. [PMID: 28583293 DOI: 10.1016/j.visres.2017.04.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 10/19/2022]
Abstract
In diabetic retinopathy, high glucose (HG)-mediated breakdown in cell-cell communication promotes disruption of retinal homeostasis. Several studies indicate that HG condition alters expression of connexin genes and subsequent gap junction intercellular communication (GJIC) in retinal vascular cells and non-vascular cells. A serious consequence of disrupted cell-cell communication is apoptosis and breakdown of the blood-retinal barrier (BRB). More recently, studies suggest adverse effects from HG on retinal Müller cells. This article focuses on HG-mediated changes in connexin expression and GJIC and their subsequent effects on the breakdown of retinal homeostasis, cell death, compromised vascular permeability, and interactions between endothelial cells, pericytes and retinal Müller cells in the pathogenesis of diabetic retinopathy. Additionally, options for rectifying disrupted homeostasis under HG condition associated with diabetic retinopathy are reviewed.
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Affiliation(s)
- Sayon Roy
- Department of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States.
| | - Dongjoon Kim
- Department of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
| | - Remington Lim
- Department of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
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16
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Roy S, Jiang JX, Li AF, Kim D. Connexin channel and its role in diabetic retinopathy. Prog Retin Eye Res 2017; 61:35-59. [PMID: 28602949 DOI: 10.1016/j.preteyeres.2017.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/30/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy is the leading cause of blindness in the working age population. Unfortunately, there is no cure for this devastating ocular complication. The early stage of diabetic retinopathy is characterized by the loss of various cell types in the retina, namely endothelial cells and pericytes. As the disease progresses, vascular leakage, a clinical hallmark of diabetic retinopathy, becomes evident and may eventually lead to diabetic macular edema, the most common cause of vision loss in diabetic retinopathy. Substantial evidence indicates that the disruption of connexin-mediated cellular communication plays a critical role in the pathogenesis of diabetic retinopathy. Yet, it is unclear how altered communication via connexin channel mediated cell-to-cell and cell-to-extracellular microenvironment is linked to the development of diabetic retinopathy. Recent observations suggest the possibility that connexin hemichannels may play a role in the pathogenesis of diabetic retinopathy by allowing communication between cells and the microenvironment. Interestingly, recent studies suggest that connexin channels may be involved in regulating retinal vascular permeability. These cellular events are coordinated at least in part via connexin-mediated intercellular communication and the maintenance of retinal vascular homeostasis. This review highlights the effect of high glucose and diabetic condition on connexin channels and their impact on the development of diabetic retinopathy.
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Affiliation(s)
- Sayon Roy
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States.
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - An-Fei Li
- Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan
| | - Dongjoon Kim
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
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17
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Zucker diabetic fatty rats, a model for type 2 diabetes, develop an inner ear dysfunction that can be attenuated by losartan treatment. Cell Tissue Res 2015; 362:307-15. [DOI: 10.1007/s00441-015-2215-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/12/2015] [Indexed: 12/13/2022]
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18
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Roy S, Bae E, Amin S, Kim D. Extracellular matrix, gap junctions, and retinal vascular homeostasis in diabetic retinopathy. Exp Eye Res 2015; 133:58-68. [PMID: 25819455 DOI: 10.1016/j.exer.2014.08.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 12/15/2022]
Abstract
The vascular basement membrane (BM) contains extracellular matrix (ECM) proteins that assemble in a highly organized manner to form a supportive substratum for cell attachment facilitating myriad functions that are vital to cell survival and overall retinal homeostasis. The BM provides a microenvironment in which bidirectional signaling through integrins regulates cell attachment, turnover, and functionality. In diabetic retinopathy, the BM undergoes profound structural and functional changes, and recent studies have brought to light the implications of such changes. Thickened vascular BM in the retinal capillaries actively participate in the development and progression of characteristic changes associated with diabetic retinopathy. High glucose (HG)-induced compromised cell-cell communication via gap junctions (GJ) in retinal vascular cells may disrupt homeostasis in the retinal microenvironment. In this review, the role of altered ECM synthesis, compromised GJ activity, and disturbed retinal homeostasis in the development of retinal vascular lesions in diabetic retinopathy are discussed.
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Affiliation(s)
- Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA.
| | - Edward Bae
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA
| | - Shruti Amin
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA
| | - Dongjoon Kim
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA
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19
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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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20
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Veeranki S, Tyagi SC. Role of hydrogen sulfide in skeletal muscle biology and metabolism. Nitric Oxide 2014; 46:66-71. [PMID: 25461301 DOI: 10.1016/j.niox.2014.11.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 11/12/2014] [Accepted: 11/21/2014] [Indexed: 02/06/2023]
Abstract
Hydrogen sulfide (H2S) is a novel endogenous gaseous signal transducer (gasotransmitter). Its emerging role in multiple facets of inter- and intra-cellular signaling as a metabolic, inflammatory, neuro and vascular modulator has been increasingly realized. Although H2S is known for its effects as an anti-hypertensive, anti-inflammatory and anti-oxidant molecule, the relevance of these effects in skeletal muscle biology during health and during metabolic syndromes is unclear. H2S has been implicated in vascular relaxation and vessel tone enhancement, which might lead to mitigation of vascular complications caused by the metabolic syndromes. Metabolic complications may also lead to mitochondrial remodeling by interfering with fusion and fission, therefore, leading to mitochondrial mitophagy and skeletal muscle myopathy. Mitochondrial protection by H2S enhancing treatments may mitigate deterioration of muscle function during metabolic syndromes. In addition, H2S might upregulate uncoupling proteins and might also cause browning of white fat, resulting in suppression of imbalanced cytokine signaling caused by abnormal fat accumulation. Likewise, as a source for H(+) ions, it has the potential to augment anaerobic ATP synthesis. However, there is a need for studies to test these putative H2S benefits in different patho-physiological scenarios before its full-fledged usage as a therapeutic molecule. The present review highlights current knowledge with regard to exogenous and endogenous H2S roles in skeletal muscle biology, metabolism, exercise physiology and related metabolic disorders, such as diabetes and obesity, and also provides future directions.
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Affiliation(s)
- Sudhakar Veeranki
- Department of Physiology & Biophysics, University of Louisville, Louisville, KY 40202, USA.
| | - Suresh C Tyagi
- Department of Physiology & Biophysics, University of Louisville, Louisville, KY 40202, USA
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21
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Rubenstein DA, Maria Z, Yin W. Combined incubation of platelets and endothelial cells with glycated albumin: Altered thrombogenic and inflammatory responses. Diab Vasc Dis Res 2014; 11:235-242. [PMID: 24821752 DOI: 10.1177/1479164114531298] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Diabetes mellitus is a salient risk factor for the development of cardiovascular diseases (CVDs). Part of this risk is associated with the presence of advanced glycation end products (AGEs), which have been shown to up-regulate platelet or endothelial cell inflammatory and thrombogenic responses that are associated with CVDs. However, platelets perform mechanisms that alter endothelial cell inflammatory and thrombogenic responses, and endothelial cells perform similar mechanisms on platelets. Thus, our goal was to evaluate platelet and endothelial cell inflammatory and thrombogenic reactions that AGEs elicit during concurrent exposure. Endothelial cells were incubated with AGEs for 5 days, after which platelets were added. A time course for CVD inflammatory and thrombogenic responses was quantified as a function of extent of glycation. In general, the presence of platelets reduced AGE-induced endothelial cell responses associated with CVD progression and the presence of endothelial cells reduced platelet adhesion and activation responses, as compared with individual exposures. In general, the presence of irreversibly glycated albumin promoted CVD development to a greater extent than reversibly glycated albumin. This suggests that under diabetic conditions, platelets and endothelial cells can negatively feedback on each other, likely via enhanced adhesion, to elicit a reduced response associated with CVD progression.
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Affiliation(s)
- David A Rubenstein
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, USA Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Zahra Maria
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, USA
| | - Wei Yin
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK, USA Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
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22
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Muto T, Tien T, Kim D, Sarthy VP, Roy S. High glucose alters Cx43 expression and gap junction intercellular communication in retinal Müller cells: promotes Müller cell and pericyte apoptosis. Invest Ophthalmol Vis Sci 2014; 55:4327-37. [PMID: 24938518 DOI: 10.1167/iovs.14-14606] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE To investigate whether high glucose (HG) alters connexin 43 (Cx43) expression and gap junction intercellular communication (GJIC) activity in retinal Müller cells, and promotes Müller cell and pericyte loss. METHODS Retinal Müller cells (rMC-1) and cocultures of rMC-1 and retinal pericytes were grown in normal (N) or HG (30 mM glucose) medium. Additionally, rMC-1 transfected with Cx43 small interfering RNA (siRNA) were grown as cocultures with pericytes, and rMC-1 transfected with Cx43 plasmid were grown in HG. Expression of Cx43 was determined by Western blotting and immunostaining and GJIC was assessed by scrape-loading dye transfer (SLDT) technique. Apoptosis was analyzed by TUNEL or differential staining assay, and Akt activation by assessing Akt phosphorylation. RESULTS In monocultures of rMC-1 and cocultures of rMC-1 and pericytes, Cx43 protein level, number of Cx43 plaques, GJIC, and Akt phosphorylation were significantly reduced in HG medium. Number of TUNEL-positive cells was also significantly increased in rMC-1 monocultures and in rMC-1 and pericyte cocultures grown in HG medium. Importantly, when rMC-1 transfected with Cx43 siRNA were grown as cocultures with pericytes, a significant decrease in GJIC, and increase in TUNEL-positive cells was observed, concomitant with decreased Akt phosphorylation. Upregulation of Cx43 rescued rMC-1 from HG-induced apoptosis. CONCLUSIONS Gap junction communication between Müller cells and pericytes is essential for their survival. Downregulation of Cx43 that is HG induced and impairment of GJIC activity in Müller cells contributes to loss of glial and vascular cells associated with the pathogenesis of diabetic retinopathy.
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Affiliation(s)
- Tetsuya Muto
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Thomas Tien
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Dongjoon Kim
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Vijay P Sarthy
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
| | - Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
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Stamper IJ, Jackson E, Wang X. Phase transitions in pancreatic islet cellular networks and implications for type-1 diabetes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:012719. [PMID: 24580269 PMCID: PMC4172977 DOI: 10.1103/physreve.89.012719] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Indexed: 06/03/2023]
Abstract
In many aspects the onset of a chronic disease resembles a phase transition in a complex dynamic system: Quantitative changes accumulate largely unnoticed until a critical threshold is reached, which causes abrupt qualitative changes of the system. In this study we examine a special case, the onset of type-1 diabetes (T1D), a disease that results from loss of the insulin-producing pancreatic islet β cells. Within each islet, the β cells are electrically coupled to each other via gap-junctional channels. This intercellular coupling enables the β cells to synchronize their insulin release, thereby generating the multiscale temporal rhythms in blood insulin that are critical to maintaining blood glucose homeostasis. Using percolation theory we show how normal islet function is intrinsically linked to network connectivity. In particular, the critical amount of β-cell death at which the islet cellular network loses site percolation is consistent with laboratory and clinical observations of the threshold loss of β cells that causes islet functional failure. In addition, numerical simulations confirm that the islet cellular network needs to be percolated for β cells to synchronize. Furthermore, the interplay between site percolation and bond strength predicts the existence of a transient phase of islet functional recovery after onset of T1D and introduction of treatment, potentially explaining the honeymoon phenomenon. Based on these results, we hypothesize that the onset of T1D may be the result of a phase transition of the islet β-cell network.
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Affiliation(s)
- I. J. Stamper
- Department of Physics, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- The Comprehensive Diabetes Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Elais Jackson
- Department of Computer and Information Sciences, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Xujing Wang
- Department of Physics, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- The Comprehensive Diabetes Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- Systems Biology Center, the National Heart, Lung, and Blood Institute, the National Institutes of Health, Bethesda, Maryland, USA
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24
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Maria Z, Yin W, Rubenstein DA. Combined effects of physiologically relevant disturbed wall shear stress and glycated albumin on endothelial cell functions associated with inflammation, thrombosis and cytoskeletal dynamics. J Diabetes Investig 2013; 5:372-81. [PMID: 25411596 PMCID: PMC4210075 DOI: 10.1111/jdi.12162] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 09/02/2013] [Accepted: 09/05/2013] [Indexed: 01/02/2023] Open
Abstract
Aims/Introduction Diabetes mellitus is a major risk factor in the development of cardiovascular diseases (CVDs). The presence of advanced glycation end‐products (AGEs) promotes CVDs by upregulating endothelial cell (EC) inflammatory and thrombotic responses, in a similar manner as disturbed shear stress. However, the combined effect of disturbed shear stress and AGEs on EC function has yet to be determined. Our goal was to evaluate these effects on EC responses. Materials and Methods ECs were incubated with AGEs for 5 days. ECs were then subjected to physiological or pathological shear stress. Cell metabolic activity, surface expression of intercellular adhesion molecule‐1, thrombomodulin, connexin‐43 and caveolin‐1, and cytoskeleton organization were quantified. Results The results show that irreversibly glycated albumin and pathological shear stress increased EC metabolic activity, and upregulated and downregulated the EC surface expression of intercellular adhesion molecule‐1 and thrombomodulin, respectively. Expression of connexin‐43, caveolin‐1 and cytoskeletal organization was independent of shear stress; however, the presence of irreversibly glycated AGEs markedly increased connexin‐43, and decreased caveolin‐1 expression and actin cytoskeletal connectivity. Conclusions Our data suggest that irreversibly glycated albumin and disturbed shear stress could promote CVD pathogenesis by enhancing EC inflammatory and thrombotic responses, and through the deterioration of the cytoskeletal organization.
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Affiliation(s)
- Zahra Maria
- School of Mechanical and Aerospace Engineering Oklahoma State University Stillwater OK USA
| | - Wei Yin
- School of Mechanical and Aerospace Engineering Oklahoma State University Stillwater OK USA
| | - David Alan Rubenstein
- School of Mechanical and Aerospace Engineering Oklahoma State University Stillwater OK USA
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Manipulating Connexin Communication Channels: Use of Peptidomimetics and the Translational Outputs. J Membr Biol 2012; 245:437-49. [PMID: 22886208 PMCID: PMC3456916 DOI: 10.1007/s00232-012-9488-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/07/2012] [Indexed: 12/22/2022]
Abstract
Gap junctions are key components underpinning multicellularity. They provide cell to cell channel pathways that enable direct intercellular communication and cellular coordination in tissues and organs. The channels are constructed of a family of connexin (Cx) membrane proteins. They oligomerize inside the cell, generating hemichannels (connexons) composed of six subunits arranged around a central channel. After transfer to the plasma membrane, arrays of Cx hemichannels (CxHcs) interact and couple with partners in neighboring attached cells to generate gap junctions. Cx channels have been studied using a range of technical approaches. Short peptides corresponding to sequences in the extra- and intracellular regions of Cxs were used first to generate epitope-specific antibodies that helped studies on the organization and functions of gap junctions. Subsequently, the peptides themselves, especially Gap26 and -27, mimetic peptides derived from each of the two extracellular loops of connexin43 (Cx43), a widely distributed Cx, have been extensively applied to block Cx channels and probe the biology of cell communication. The development of a further series of short peptides mimicking sequences in the intracellular loop, especially the extremity of the intracellular carboxyl tail of Cx43, followed. The primary inhibitory action of the peptidomimetics occurs at CxHcs located at unapposed regions of the cell’s plasma membrane, followed by inhibition of cell coupling occurring across gap junctions. CxHcs respond to a range of environmental conditions by increasing their open probability. Peptidomimetics provide a way to block the actions of CxHcs with some selectivity. Furthermore, they are increasingly applied to address the pathological consequences of a range of environmental stresses that are thought to influence Cx channel operation. Cx peptidomimetics show promise as candidates in developing new therapeutic approaches for containing and reversing damage inflicted on CxHcs, especially in hypoxia and ischemia in the heart and in brain functions.
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