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Zhu L, Fang S, Liu W, Zhang H, Zhang Y, Xie Z, Yang P, Wan J, Gao B, Lucy Yu L. The triacylglycerol structure and composition of a human milk fat substitute affect the absorption of fatty acids and calcium, lipid metabolism and bile acid metabolism in newly-weaned Sprague-Dawley rats. Food Funct 2023; 14:7574-7585. [PMID: 37526948 DOI: 10.1039/d2fo01800d] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
In this study, the effect of sn-2 palmitic triacylglycerols (sn-2 palmitic TAGs) and the ratio between the two major sn-2 palmitic TAGs (OPL to OPO ratio) in a human milk fat substitute (HMFS) on growth, fatty acid and calcium absorptions, and lipid and bile acid metabolic alterations was investigated in Sprague-Dawley rats. After 4 weeks of high-fat feeding, rats fed with the HMFS containing a sn-2 palmitic acid content of 57.87% and an OPL to OPO ratio of 1.4 showed the lowest TAG accumulation in their livers and hypertrophy of perirenal adipocytes, compared to the groups fed with fats containing a lower sn-2 palmitic acid content or a lower OPL to OPO ratio. Meanwhile, synergistically improved absorption of fatty acids and calcium and increased levels of total bile acids (BAs), especially for the tauro-conjugated BAs (TCDCA, TUDCA, TαMCA, TβMCA, TDCA and TωMCA), were observed in rats by both increasing the sn-2 palmitic acid content and the OPL to OPO ratio in HMFS. In addition, the levels of total BAs and tauro-conjugated BAs were negatively correlated with serum TAG, TC, and LDL-c levels and positively correlated with HDL-c levels according to Spearman's correlation analysis (P < 0.05). Collectively, these findings present new nutritional evidence for the potential effects of the TAG structure and composition of a human milk fat substitute on the growth and lipid and bile acid metabolism of the host in infancy.
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Affiliation(s)
- Lin Zhu
- Institute of Food and Nutraceutical Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Shuaizhen Fang
- Institute of Food and Nutraceutical Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Wenwen Liu
- Institute of Food and Nutraceutical Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Hong Zhang
- Wilmar (Shanghai) Biotechnology Research & Development Center Co. Ltd, Shanghai 200137, China
| | - Yaqiong Zhang
- Institute of Food and Nutraceutical Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Zhuohong Xie
- Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20742, USA
| | - Puyu Yang
- Institute of Food and Nutraceutical Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Jianchun Wan
- Wilmar (Shanghai) Biotechnology Research & Development Center Co. Ltd, Shanghai 200137, China
| | - Boyan Gao
- Institute of Food and Nutraceutical Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Liangli Lucy Yu
- Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20742, USA
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Bridges LE, Williams CL, Awumey EM. High Salt Upregulates Ca 2+-Sensing Receptor Expression and Ca 2+-Induced Relaxation of Contracted Mesenteric Arteries from Dahl Salt-Sensitive Rats. J Pharmacol Exp Ther 2022; 381:120-128. [PMID: 35306475 PMCID: PMC9048267 DOI: 10.1124/jpet.121.001034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/01/2022] [Indexed: 11/22/2022] Open
Abstract
High Ca2+ lowers blood pressure in hypertension, but the mechanism is not clear. The missing link may be the perivascular sensory nerve Ca2+-sensing receptor (CaSR) that mediates a vasodilator system after activation by interstitial Ca2+ Our results show that high salt increased CaSR expression in mesenteric arteries as well as Ca2+ relaxation of contracted mesenteric arteries from salt-sensitive (SS) rats. The CaSR was expressed as a doublet (≈120-150 kDa) in arteries from animals fed a high-salt diet for 1-4 weeks. The higher molecular weight glycosylated protein increased in arteries from SS animals; however, expression of the low molecular mass high-mannose protein decreased over 4 weeks of feeding the diet. In tissues from salt-resistant (SR) rats, the diet decreased CaSR expression after 4 weeks. Ca2+ relaxation of mesenteric arteries under phenylephrine tone increased in SS rats but decreased in arteries from SR rats fed the high-salt diet. Ca2+-activated K+ channels have a larger role in Ca2+ relaxation of arteries in SR than SS rats. The data suggest that high salt epigenetically regulates the receptor at the translational level in vivo and that the in vitro effect of Ca2+ is on receptor trafficking and signaling. In conclusion, upregulated expression of the CaSR in salt sensitivity increased receptor-mediated vascular relaxation. These findings show that CaSR signaling may compensate for changes in the vasculature in salt-sensitive hypertension. SIGNIFICANCE STATEMENT: The perivascular sensory nerve Ca2+-sensing receptor (CaSR) mediates Ca2+ relaxation of isolated mesenteric arteries under tension. This receptor may therefore play a significant role in relaxation of resistance arteries in vivo, thus explaining the blood pressure-lowering effect of dietary Ca2+. The present studies describe the effect of high salt-induced upregulation of the CaSR in salt-sensitive rats and the roles played by Ca2+-activated K+ channels and nitric oxide in Ca2+ responses.
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Affiliation(s)
- Lakeesha E Bridges
- Julius L. Chambers Biomedical and Biotechnology Research Institute (L.E.B., C.L.W., E.M.A.) and Department of Biological and Biomedical Sciences (E.M.A.), North Carolina Central University, Durham, North Carolina; and Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston Salem, North Carolina (E.M.A.)
| | - Cicely L Williams
- Julius L. Chambers Biomedical and Biotechnology Research Institute (L.E.B., C.L.W., E.M.A.) and Department of Biological and Biomedical Sciences (E.M.A.), North Carolina Central University, Durham, North Carolina; and Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston Salem, North Carolina (E.M.A.)
| | - Emmanuel M Awumey
- Julius L. Chambers Biomedical and Biotechnology Research Institute (L.E.B., C.L.W., E.M.A.) and Department of Biological and Biomedical Sciences (E.M.A.), North Carolina Central University, Durham, North Carolina; and Department of Physiology and Pharmacology and Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston Salem, North Carolina (E.M.A.)
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Kim P, Chu N, Davis J, Kim DH. Mechanoregulation of Myofibroblast Fate and Cardiac Fibrosis. ADVANCED BIOSYSTEMS 2018; 2:1700172. [PMID: 31406913 PMCID: PMC6690497 DOI: 10.1002/adbi.201700172] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
During myocardial infarction, myocytes die and are replaced by a specialized fibrotic extracellular matrix, otherwise known as scarring. Fibrotic scarring presents a tremendous hemodynamic burden on the heart, as it creates a stiff substrate, which resists diastolic filling. Fibrotic mechanisms result in permanent scarring which often leads to hypertrophy, arrhythmias, and a rapid progression to failure. Despite the deep understanding of fibrosis in other tissues, acquired through previous investigations, the mechanisms of cardiac fibrosis remain unclear. Recent studies suggest that biochemical cues as well as mechanical cues regulate cells in myocardium. However, the steps in myofibroblast transdifferentiation, as well as the molecular mechanisms of such transdifferentiation in vivo, are poorly understood. This review is focused on defining myofibroblast physiology, scar mechanics, and examining current findings of myofibroblast regulation by mechanical stress, stiffness, and topography for understanding fibrotic disease dynamics.
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Affiliation(s)
- Peter Kim
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Nick Chu
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Jennifer Davis
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Deok-Ho Kim
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
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An emerging role for gasotransmitters in the control of breathing and ionic regulation in fish. J Comp Physiol B 2015; 186:145-59. [DOI: 10.1007/s00360-015-0949-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 11/04/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
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Krafft MP. Overcoming inactivation of the lung surfactant by serum proteins: a potential role for fluorocarbons? SOFT MATTER 2015; 11:5982-5994. [PMID: 26110877 DOI: 10.1039/c5sm00926j] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In many pulmonary conditions serum proteins interfere with the normal adsorption of components of the lung surfactant to the surface of the alveoli, resulting in lung surfactant inactivation, with potentially serious untoward consequences. Here, we review the strategies that have recently been designed in order to counteract the biophysical mechanisms of inactivation of the surfactant. One approach includes protein analogues or peptides that mimic the native proteins responsible for innate resistance to inactivation. Another perspective uses water-soluble additives, such as electrolytes and hydrophilic polymers that are prone to enhance adsorption of phospholipids. An alternative, more recent approach consists of using fluorocarbons, that is, highly hydrophobic inert compounds that were investigated for partial liquid ventilation, that modify interfacial properties and can act as carriers of exogenous lung surfactant. The latter approach that allows fluidisation of phospholipid monolayers while maintaining capacity to reach near-zero surface tension definitely warrants further investigation.
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Affiliation(s)
- Marie Pierre Krafft
- Institut Charles Sadron (CNRS), University of Strasbourg, 23 rue du Loess, 67034 Strasbourg Cedex, France.
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Abstract
PURPOSE Regional heterogeneity in mitral annular contraction, which is generally ascribed to the fibrous vs. muscular annular composition, ensures proper leaflet motion and timing of coaptation. It is unknown whether the fibroblast-like cells in the annulus modulate this heterogeneity, even though valvular interstitial cells (VICs) can be mechanically "activated." METHODS Fourteen sheep underwent implantation of radiopaque markers around the mitral annulus defining four segments: septal (SEPT), lateral (LAT), and anterior (ANT-C) and posterior (POST-C) commissures. Segmental annular contraction was calculated using biplane videofluoroscopy. Immunohistochemistry of annular cross sections assessed regional matrix content, matrix turnover, and cell phenotype. Micropipette aspiration measured the Young's modulus of the leaflets adjacent to the myocardial border. RESULTS Whereas SEPT contained more collagen I and III, LAT demonstrated more collagen and elastin turnover as shown by greater decorin, lysyl oxidase, and matrix metalloprotease (MMP)-13 and smooth muscle alpha-actin (SMaA). This greater matrix turnover paralleled greater annular contraction in LAT vs. SEPT (22.5% vs. 4.1%). Similarly, POST-C had more SMaA and MMP13 than ANT-C, consistent with greater annular contraction in POST-C (18.8% vs. 11.1%). Interestingly, POST-C had the greatest effective modulus, significantly higher than LAT. CONCLUSIONS These data suggest that matrix turnover by activated VICs relates to annular motion heterogeneity, maintains steady-state mechanical properties in the annulus, and could be a therapeutic target when annular motion is impaired. Conversely, alterations in this heterogeneous annular contraction, whether through disease or secondary to ring annuloplasty, could disrupt this normal pattern of cell-mediated matrix remodeling and further adversely impact mitral valve function.
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Sesay JS, Gyapong RNK, Najafi LT, Kabler SL, Diz DI, Howlett AC, Awumey EM. Gαi/o-dependent Ca(2+) mobilization and Gαq-dependent PKCα regulation of Ca(2+)-sensing receptor-mediated responses in N18TG2 neuroblastoma cells. Neurochem Int 2015; 90:142-51. [PMID: 26190181 DOI: 10.1016/j.neuint.2015.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 06/24/2015] [Accepted: 07/14/2015] [Indexed: 01/14/2023]
Abstract
A functional Ca(2+)-sensing receptor (CaS) is expressed endogenously in mouse N18TG2 neuroblastoma cells, and sequence analysis of the cDNA indicates high homology with both rat and human parathyroid CaS cDNAs. The CaS in N18TG2 cells appears as a single immunoreactive protein band at about 150 kDa on Western blots, consistent with native CaS from dorsal root ganglia. Both wild type (WT) and Gαq antisense knock-down (KD) cells responded to Ca(2+) and calindol, a positive allosteric modulator of the CaS, with a transient increase in intracellular Ca(2+) concentration ([Ca(2+)]i), which was larger in the Gαq KD cells. Stimulation with 1 mM extracellular Ca(2+) (Ca(2+)e) increased [Ca(2+)]i in N18TG2 Gαq KD compared to WT cells. Ca(2+) mobilization was dependent on pertussis toxin-sensitive Gαi/o proteins and reduced by 30 μM 2-amino-ethyldiphenyl borate and 50 μM nifedipine to the same plateau levels in both cell types. Membrane-associated PKCα and p-PKCα increased with increasing [Ca(2+)]e in WT cells, but decreased in Gαq KD cells. Treatment of cells with 1 μM Gӧ 6976, a Ca(2+)-specific PKC inhibitor reduced Ca(2+) mobilization and membrane-associated PKCα and p-PKCα in both cell types. The results indicate that the CaS-mediated increase in [Ca(2+)]i in N18TG2 cells is dependent on Gαi/o proteins via inositol-1,4,5-triphosphate (IP3) channels and store-operated Ca(2+) entry channels, whereas modulation of CaS responses involving PKCα phosphorylation and translocation to the plasma membrane occurs via a Gαq mechanism.
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Affiliation(s)
- John S Sesay
- Cardiovascular Disease Research Program, Julius L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA; Department of Biology, North Carolina Central University, Durham, NC 27707, USA; Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Reginald N K Gyapong
- Cardiovascular Disease Research Program, Julius L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA
| | - Leila T Najafi
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, MO 63104, USA
| | - Sandra L Kabler
- Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Debra I Diz
- Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA; Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Allyn C Howlett
- Department of Biology, North Carolina Central University, Durham, NC 27707, USA; Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, MO 63104, USA; Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA; Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Emmanuel M Awumey
- Cardiovascular Disease Research Program, Julius L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA; Department of Biology, North Carolina Central University, Durham, NC 27707, USA; Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA; Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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Zhou CY, Wu H, Devaraj NK. Rapid access to phospholipid analogs using thiol-yne chemistry. Chem Sci 2015; 6:4365-4372. [PMID: 29218208 PMCID: PMC5707512 DOI: 10.1039/c5sc00653h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/15/2015] [Indexed: 12/22/2022] Open
Abstract
Phospholipids and glycolipids constitute an essential part of biological membranes, and are of tremendous fundamental and practical interest. Unfortunately, the preparation of functional phospholipids, or synthetic analogs, is often synthetically challenging. Here we utilize thiol-yne click chemistry methodology to gain access to phospho- and glycolipid analogs. Alkynyl hydrophilic head groups readily photoreact with numerous thiol modified lipid tails to yield the appropriate dithioether phospho- or glycolipids. The resulting structures closely resemble the structure and function of native diacylglycerolipids. Dithioether phosphatidylcholines (PCs) are suitable for forming giant unilamellar vesicles (GUV), which can be used as vessels for cell-free expression systems. The unnatural thioether linkages render the lipids resistant to phospholipase A2 hydrolysis. We utilize the improved stability of these lipids to control the shrinkage of GUVs composed of a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and dioleyl-dithioether PC, concentrating encapsulated nanoparticles. We imagine that these readily accessible lipids could find a number of applications as natural lipid substitutes.
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Affiliation(s)
- Cun Yu Zhou
- Department of Chemistry and Biochemistry , University of California , San Diego , La Jolla , California 92093 , USA .
| | - Haoxing Wu
- Department of Chemistry and Biochemistry , University of California , San Diego , La Jolla , California 92093 , USA .
| | - Neal Krishna Devaraj
- Department of Chemistry and Biochemistry , University of California , San Diego , La Jolla , California 92093 , USA .
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Rimensberger PC. Surfactant. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7175631 DOI: 10.1007/978-3-642-01219-8_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Exogenous pulmonary surfactant, widely used in neonatal care, is one of the best-studied treatments in neonatology, and its introduction in the 1990s led to a significant improvement in neonatal outcomes in preterm infants, including a decrease in mortality. This chapter provides an overview of surfactant composition and function in health and disease and summarizes the evidence for its clinical use.
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Affiliation(s)
- Peter C. Rimensberger
- Service of Neonatology and Pediatric Intensive Care, Department of Pediatrics, University Hospital of Geneva, Geneve, Switzerland
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Moraes C, Likhitpanichkul M, Lam CJ, Beca BM, Sun Y, Simmons CA. Microdevice array-based identification of distinct mechanobiological response profiles in layer-specific valve interstitial cells. Integr Biol (Camb) 2013; 5:673-80. [PMID: 23403640 DOI: 10.1039/c3ib20254b] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Aortic valve homeostasis is mediated by valvular interstitial cells (VICs) found in spatially distinct and mechanically dynamic layers of the valve leaflet. Disease progression is associated with the pathological differentiation of VICs to myofibroblasts, but the mechanobiological response profiles of cells specific to different layers in the leaflet remains undefined. Conventional mechanically dynamic macroscale culture technologies require a large number of cells per set of environmental conditions. However, large scale expansion of primary VICs in vitro does not maintain in vivo phenotypes, and hence conventional macroscale techniques are not well-suited to systematically probe response of these cell types to combinatorially manipulated mechanobiological cues. To address this issue, we developed a microfabricated composite material screening array to determine the combined effects of dynamic substrate stretch, soluble cues and matrix proteins on small populations of primary cells. We applied this system to study VICs isolated from distinct layers of the valve leaflet and determined that (1) mechanical stability and cellular adhesion to the engineered composite materials were significantly improved as compared to conventional stretching technologies; (2) VICs demonstrate layer-specific mechanobiological profiles; and (3) mechanical stimulation, matrix proteins and soluble cues produce integrated and distinct responses in layer-specific VIC populations. Strikingly, myofibroblast differentiation was most significantly influenced by cell origin, despite the presence of potent mechanobiological cues such as applied strain and TGF-β1. These results demonstrate that spatially-distinct VIC subpopulations respond differentially to microenvironmental cues, with implications for valve tissue engineering and pathobiology. The developed platform enables rapid identification of biological phenomena arising from systematically manipulating the cellular microenvironment, and may be of utility in screening mechanosensitive cell cultures with applications in drug screening, tissue engineering and fundamental cell biology.
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Affiliation(s)
- Christopher Moraes
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada
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Gu Q, Vysotskaya ZV, Moss CR, Kagira MK, Gilbert CA. Calcium-sensing receptor in rat vagal bronchopulmonary sensory neurons regulates the function of the capsaicin receptor TRPV1. Exp Physiol 2013; 98:1631-42. [PMID: 23913765 DOI: 10.1113/expphysiol.2013.074633] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Extracellular calcium-sensing receptor (CaSR) has been known to play a critical role in the maintainance of systemic Ca(2+) homeostasis. Recent studies have shown that CaSR is also expressed in many tissues that are not directly related to plasma Ca(2+) regulation, such as the central and peripheral nervous system, where the function of this receptor remains to be defined. In this study, we aimed to investigate the expression of CaSR and its potential interaction with transient receptor potential vanilloid receptor type 1 (TRPV1) in rat vagal bronchopulmonary sensory neurons. Our immunohistochemical experiments demonstrated the expression of CaSR in these sensory neurons as well as in trachea and lung parenchyma. Results from our whole-cell patch-clamp recordings in isolated neurons showed that strong activation of CaSR with high concentrations of its agonists, including spermine, NPS R-568 and Ca(2+), inhibited the capsaicin-evoked whole-cell inward current. Blockade of CaSR with its antagonists NPS 2390 and NPS 2143 significantly enhanced the capsaicin-evoked TRPV1 current. These data suggest that CaSR is likely to be involved in the integration of primary bronchopulmonary sensory inputs in physiological and/or pathophysiological conditions.
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Affiliation(s)
- Qihai Gu
- Q. Gu: Division of Basic Medical Sciences, Mercer University School of Medicine, 1550 College Street, Macon, GA 31207, USA.
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Kishi T. Regulation of the sympathetic nervous system by nitric oxide and oxidative stress in the rostral ventrolateral medulla: 2012 Academic Conference Award from the Japanese Society of Hypertension. Hypertens Res 2013; 36:845-51. [DOI: 10.1038/hr.2013.73] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 03/01/2013] [Accepted: 03/26/2013] [Indexed: 02/07/2023]
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Firth AL, Won JY, Park WS. Regulation of ca(2+) signaling in pulmonary hypertension. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2013; 17:1-8. [PMID: 23439762 PMCID: PMC3579099 DOI: 10.4196/kjpp.2013.17.1.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 12/12/2012] [Accepted: 12/18/2012] [Indexed: 01/08/2023]
Abstract
Understanding the cellular and molecular mechanisms involved in the development and progression of pulmonary hypertension (PH) remains imperative if we are to successfully improve the quality of life and life span of patients with the disease. A whole plethora of mechanisms are associated with the development and progression of PH. Such complexity makes it difficult to isolate one particular pathway to target clinically. Changes in intracellular free calcium concentration, the most common intracellular second messenger, can have significant impact in defining the pathogenic mechanisms leading to its development and persistence. Signaling pathways leading to the elevation of [Ca(2+)](cyt) contribute to pulmonary vasoconstriction, excessive proliferation of smooth muscle cells and ultimately pulmonary vascular remodeling. This current review serves to summarize the some of the most recent advances in the regulation of calcium during pulmonary hypertension.
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Affiliation(s)
- Amy L Firth
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, California, USA
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Identification and characterization of novel perivascular adventitial cells in the whole mount mesenteric branch artery using immunofluorescent staining and scanning confocal microscopy imaging. Int J Cell Biol 2012; 2012:172746. [PMID: 22481943 PMCID: PMC3296306 DOI: 10.1155/2012/172746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/11/2011] [Accepted: 11/15/2011] [Indexed: 11/30/2022] Open
Abstract
A novel perivascular adventitial cell termed, adventitial neuronal somata (ANNIES) expressing the neural cell adhesion molecule (NCAM) and the vasodilator neuropeptide, calcitonin gene-related peptide (CGRP), exists in the adult rat mesenteric branch artery (MBA) in situ. In addition, we have previously shown that ANNIES coexpress CGRP and NCAM. We now show that ANNIES express the neurite growth marker, growth associated protein-43(Gap-43), palladin, and the calcium sensing receptor (CaSR), that senses changes in extracellular Ca(2+) and participates in vasodilator mechanisms. Thus, a previously characterized vasodilator, calcium sensing autocrine/paracrine system, exists in the perivascular adventitia associated with neural-vascular interface. Images of the whole mount MBA segments were analyzed under scanning confocal microscopy. Confocal analysis showed that the Gap-43, CaSR, and palladin were present in ANNIES about 37 ± 4%, 94 ± 6%, and 80 ± 10% respectively, comparable to CGRP (100%). Immunoblots from MBA confirmed the presence of Gap-43 (48 kD), NCAM (120 and 140 kD), and palladin (90–92 and 140 kD). In summary, CGRP, and NCAM-containing neural cells in the perivascular adventitia also express palladin and CaSR, and coexpress Gap-43 which may participate in response to stress/injury and vasodilator mechanisms as part of a perivascular sensory neural network.
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Davey AE, Leach K, Valant C, Conigrave AD, Sexton PM, Christopoulos A. Positive and negative allosteric modulators promote biased signaling at the calcium-sensing receptor. Endocrinology 2012; 153:1232-41. [PMID: 22210744 DOI: 10.1210/en.2011-1426] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor whose function can be allosterically modulated in a positive or negative manner by calcimimetics or calcilytics, respectively. Indeed, the second-generation calcimimetic, cinacalcet, has proven clinically useful in the treatment of chronic kidney disease patients with secondary hyperparathyroidism but is not widely used in earlier stages of renal disease due to the potential to predispose such patients to hypocalcaemia and hyperphosphatemia. The development of a biased CaSR ligand that is more selective for specific signaling pathway(s) leading only to beneficial effects may overcome this limitation. The detection of such stimulus-bias at a G protein-coupled receptor requires investigation across multiple signaling pathways and the development of methods to quantify the effects of allosteric ligands on orthosteric ligand affinity and cooperativity at each pathway. In the current study, we determined the effects of the calcimimetics, NPS-R568 or cinacalcet, and the calcilytic, NPS-2143, on Ca(o)(2+)-mediated intracellular Ca(2+) mobilization, ERK1/2 phosphorylation, and plasma membrane ruffling in a stably transfected human embryonic kidney 293-TREx c-myc-CaSR cell line and applied a novel analytical model to quantify these modulator effects. We present quantitative evidence for the generation of stimulus bias by both positive and negative allosteric modulators of the CaSR, manifested as greater allosteric modulation of intracellular Ca(2+) mobilization relative to ERK1/2 phosphorylation, and a higher affinity of the modulators for the state of the CaSR mediating plasma membrane ruffling relative to the other two pathways. Our findings provide the first evidence that an allosteric modulator used in clinical practice exhibits stimulus bias.
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Affiliation(s)
- Anna E Davey
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
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Schwan AL, Singh SP, Davy JA, Waring AJ, Gordon LM, Walther FJ, Wang Z, Notter RH. Synthesis and activity of a novel diether phosphonoglycerol in phospholipase-resistant synthetic lipid:peptide lung surfactants(). MEDCHEMCOMM 2011; 2:1167-1173. [PMID: 22530092 PMCID: PMC3331712 DOI: 10.1039/c1md00206f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This paper reports the chemical synthesis and purification of a novel phospholipase-resistant C16:0, C16:1 diether phosphonoglycerol with structural analogy to ester-linked anionic phosphatidylglycerol (PG) in endogenous pulmonary surfactant. This diether phosphonoglycerol (PG 1) is studied for phospholipase A(2) (PLA(2)) resistance and for surface activity in synthetic exogenous surfactants combined with Super Mini-B (S-MB) peptide and DEPN-8, a previously-reported diether phosphonolipid analog of dipalmitoyl phosphatidylcholine (DPPC, the major zwitterionic phospholipid in native lung surfactant). Activity experiments measured both adsorption and dynamic surface tension lowering due to the known importance of these surface behaviors in lung surfactant function in vivo. Synthetic surfactants containing 9 : 1 DEPN-8:PG 1 + 3% S-MB were resistant to degradation by PLA(2) in chromatographic studies, while calf lung surfactant extract (CLSE, the substance of the bovine clinical surfactant Infasurf®) was significantly degraded by PLA(2). The 9 : 1 DEPN-8:PG 1 + 3% S-MB mixture also had small but consistent increases in both adsorption and dynamic surface tension lowering ability compared to DEPN-8 + 3% S-MB. Consistent with these surface activity increases, molecular dynamics simulations using Protein Modeller, GROMACS force-field, and PyMOL showed that bilayers containing DPPC and palmitoyl-oleoyl-PC (POPC) as surrogates of DEPN-8 and PG 1 were penetrated to a greater extent by S-MB peptide than bilayers of DPPC alone. These results suggest that PG 1 or related anionic phosphono-PG analogs may have functional utility in phospholipase-resistant synthetic surfactants targeting forms of acute pulmonary injury where endogenous surfactant becomes dysfunctional due to phospholipase activity in the innate inflammatory response.
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Affiliation(s)
- Adrian L Schwan
- Department of Chemistry, University of Guelph, Guelph, ON, Canada N1G 2W1
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17
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Takahashi H, Yoshika M, Komiyama Y, Nishimura M. The central mechanism underlying hypertension: a review of the roles of sodium ions, epithelial sodium channels, the renin-angiotensin-aldosterone system, oxidative stress and endogenous digitalis in the brain. Hypertens Res 2011; 34:1147-60. [PMID: 21814209 PMCID: PMC3324327 DOI: 10.1038/hr.2011.105] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/08/2011] [Accepted: 05/15/2011] [Indexed: 02/07/2023]
Abstract
The central nervous system has a key role in regulating the circulatory system by modulating the sympathetic and parasympathetic nervous systems, pituitary hormone release, and the baroreceptor reflex. Digoxin- and ouabain-like immunoreactive materials were found >20 years ago in the hypothalamic nuclei. These factors appeared to localize to the paraventricular and supraoptic nuclei and the nerve fibers at the circumventricular organs and supposed to affect electrolyte balance and blood pressure. The turnover rate of these materials increases with increasing sodium intake. As intracerebroventricular injection of ouabain increases blood pressure via sympathetic activation, an endogenous digitalis-like factor (EDLF) was thought to regulate cardiovascular system-related functions in the brain, particularly after sodium loading. Experiments conducted mainly in rats revealed that the mechanism of action of ouabain in the brain involves sodium ions, epithelial sodium channels (ENaCs) and the renin-angiotensin-aldosterone system (RAAS), all of which are affected by sodium loading. Rats fed a high-sodium diet develop elevated sodium levels in their cerebrospinal fluid, which activates ENaCs. Activated ENaCs and/or increased intracellular sodium in neurons activate the RAAS; this releases EDLF in the brain, activating the sympathetic nervous system. The RAAS promotes oxidative stress in the brain, further activating the RAAS and augmenting sympathetic outflow. Angiotensin II and aldosterone of peripheral origin act in the brain to activate this cascade, increasing sympathetic outflow and leading to hypertension. Thus, the brain Na(+)-ENaC-RAAS-EDLF axis activates sympathetic outflow and has a crucial role in essential and secondary hypertension. This report provides an overview of the central mechanism underlying hypertension and discusses the use of antihypertensive agents.
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Affiliation(s)
- Hakuo Takahashi
- Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Hirakata City, Osaka, Japan.
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18
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Spontaneous glutamate release is independent of calcium influx and tonically activated by the calcium-sensing receptor. J Neurosci 2011; 31:4593-606. [PMID: 21430159 DOI: 10.1523/jneurosci.6398-10.2011] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spontaneous release of glutamate is important for maintaining synaptic strength and controlling spike timing in the brain. Mechanisms regulating spontaneous exocytosis remain poorly understood. Extracellular calcium concentration ([Ca(2+)](o)) regulates Ca(2+) entry through voltage-activated calcium channels (VACCs) and consequently is a pivotal determinant of action potential-evoked vesicle fusion. Extracellular Ca(2+) also enhances spontaneous release, but via unknown mechanisms. Here we report that external Ca(2+) triggers spontaneous glutamate release more weakly than evoked release in mouse neocortical neurons. Blockade of VACCs has no effect on the spontaneous release rate or its dependence on [Ca(2+)](o). Intracellular [Ca(2+)] slowly increases in a minority of neurons following increases in [Ca(2+)](o). Furthermore, the enhancement of spontaneous release by extracellular calcium is insensitive to chelation of intracellular calcium by BAPTA. Activation of the calcium-sensing receptor (CaSR), a G-protein-coupled receptor present in nerve terminals, by several specific agonists increased spontaneous glutamate release. The frequency of spontaneous synaptic transmission was decreased in CaSR mutant neurons. The concentration-effect relationship for extracellular calcium regulation of spontaneous release was well described by a combination of CaSR-dependent and CaSR-independent mechanisms. Overall these results indicate that extracellular Ca(2+) does not trigger spontaneous glutamate release by simply increasing calcium influx but stimulates CaSR and thereby promotes resting spontaneous glutamate release.
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19
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Huang BS, Leenen FHH. Mineralocorticoid Actions in the Brain and Hypertension. Curr Hypertens Rep 2011; 13:214-20. [DOI: 10.1007/s11906-011-0192-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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20
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Pulmonary Surfactant: Biology and Therapy. THE RESPIRATORY TRACT IN PEDIATRIC CRITICAL ILLNESS AND INJURY 2009. [PMCID: PMC7124042 DOI: 10.1007/978-1-84800-925-7_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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21
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Spermine biphasically affects N-type calcium channel currents in adult dorsal root ganglion neurons of the rat. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2437-43. [DOI: 10.1016/j.bbamem.2008.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 06/18/2008] [Accepted: 07/09/2008] [Indexed: 11/20/2022]
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22
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Diz DI, Varagic J, Groban L. Aging and the brain renin-angiotensin system: relevance to age-related decline in cardiac function. Future Cardiol 2008; 4:237-45. [PMID: 19804328 PMCID: PMC2929677 DOI: 10.2217/14796678.4.3.237] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
This article discusses evidence that impairments in control of autonomic outflow mediated by the brain renin-angiotensin system (RAS) contribute to the decline in baroreceptor reflex function and the development of insulin resistance that accompany hypertension and excess salt intake, especially during aging. Imbalances in the regulation of the sympathetic and parasympathetic limbs of the autonomic nervous system observed in older subjects underlie changes in heart-rate variability and play a role in the regulation of overall cardiac function. Age-related alterations in autonomic nervous system function may also explain the age-associated alterations in metabolism. Reduced heart-rate variability is linked to increased mortality in patients with cardiovascular disorders and, coupled with information that is known about local changes in the cardiac and brain RAS during aging, the evidence reveals potential mechanisms for the protective effects of systemic blockade of the RAS against age-related changes that impact the heart.
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Affiliation(s)
- Debra I Diz
- Wake Forest University School of Medicine, The Hypertension & Vascular Research Center, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA, Tel.: +1 336 716 2150; Fax: +1 336 716 2456;
| | - Jasmina Varagic
- Wake Forest University School of Medicine, The Hypertension & Vascular Research Center, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA, Tel.: +1 336 716 2738; Fax: +1 336 716 2456;
| | - Leanne Groban
- Wake Forest University School of Medicine, Department of Anesthesiology, Medical Center Boulevard, Winston-Salem, NC 27157-1032, USA, Tel.: +1 336 716 1187; Fax: +1 336 716 8190;
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23
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Faragher RJ, Schwan AL. New Deuterated Oligo(ethylene glycol) Building Blocks and Their Use in the Preparation of Surface Active Lipids Possessing Labeled Hydrophilic Tethers. J Org Chem 2008; 73:1371-8. [DOI: 10.1021/jo701979z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robert J. Faragher
- Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Adrian L. Schwan
- Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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24
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Heyeraas KJ, Haug SR, Bukoski RD, Awumey EM. Identification of a Ca2+-sensing receptor in rat trigeminal ganglia, sensory axons, and tooth dental pulp. Calcif Tissue Int 2008; 82:57-65. [PMID: 18175029 DOI: 10.1007/s00223-007-9096-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 11/14/2007] [Indexed: 10/22/2022]
Abstract
Extracellular Ca2+ regulates dentin formation, but little information is available on this regulatory mechanism. We have previously reported that sensory denervation reduces dentin formation, suggesting a role for sensory nerves in tooth mineralization. The G protein-coupled Ca2+-sensing receptor (CaR) is expressed in dorsal root ganglia and perivascular sensory nerves in mesenteric arterioles, and activation of these receptors by Ca2+ has been shown to induce vascular relaxation. The present study determined CaR expression in tooth dental pulp (DP), sensory axons, and trigeminal ganglion (TG) as well as the effect of increased [Ca2+]e or a calcimimetic on tooth blood flow. The distribution of CaR, studied by immunochemistry, RT-PCR, and Western blot, indicates abundant expression of CaR in sensory axons in the jaws, TG, and DP. Restriction analysis of PCR products with specific endonucleases showed the presence of CaR message in TG and DP, and Western blotting indicates the expression of mature and immature forms of the receptor in these tissues. Pulpal blood flow, measured by laser-Doppler flowmetry, increased by 67% +/- 6% (n = 12) following receptor stimulation with 5 mM Ca2+, which was completely inhibited by 5 microM IBTx, a high-conductance KCa channel blocker indicating a mechanism involving hyperpolarization. NPS R-467 (10 microM) increased blood flow by 85% +/- 18% (n = 6), suggesting regulation through the CaR. Our results suggest that the CaR is present in sensory nerves, DP, and TG and that an increase in Ca2+ in the DP causes vasodilatation, which may contribute to accumulation of Ca2+ during dentin mineralization.
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Affiliation(s)
- Karin J Heyeraas
- Department of Biomedicine, Section for Physiology, Faculty of Medicine, University of Bergen, Jonas Lies vei 91, N-5009, Bergen, Norway.
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25
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Yoshimura N, Kaiho Y, Miyazato M, Yunoki T, Tai C, Chancellor MB, Tyagi P. Therapeutic receptor targets for lower urinary tract dysfunction. Naunyn Schmiedebergs Arch Pharmacol 2007; 377:437-48. [PMID: 18034230 DOI: 10.1007/s00210-007-0209-z] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 10/22/2007] [Indexed: 01/25/2023]
Abstract
The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the bladder, urethra, and external urethral sphincter. During urine storage, the outlet is closed, and the bladder smooth muscle is quiescent. When bladder volume reaches the micturition threshold, activation of a micturition center in the dorsolateral pons (the pontine micturition center) induces a bladder contraction and a reciprocal relaxation of the urethra, leading to bladder emptying. During voiding, sacral parasympathetic (pelvic) nerves provide an excitatory input (cholinergic and purinergic) to the bladder and inhibitory input (nitrergic) to the urethra. These peripheral systems are integrated by excitatory and inhibitory regulation at the levels of the spinal cord and the brain. Injury or diseases of the nervous system, as well as drugs and disorders of the peripheral organs, can produce lower urinary tract dysfunction. In the overactive bladder (OAB) condition, therapeutic targets for facilitation of urine storage can be found at the levels of the urothelium, detrusor muscles, autonomic and afferent pathways, spinal cord, and brain. There is increasing evidence showing that the urothelium has specialized sensory and signaling properties including: (1) expression of nicotinic, muscarinic, tachykinin, adrenergic, bradykinin, and transient receptor potential (TRP) receptors, (2) close physical association with afferent nerves, and (3) ability to release chemical molecules such as adenosine triphosphate (ATP), acetylcholine, and nitric oxide. Increased expression and/or sensitivity of these urothelial-sensory molecules that lead to afferent sensitization have been documented as possible pathogenesis of OAB. Targeting afferent pathways and/or bladder smooth muscles by modulating activity of ligand receptors (e.g., neurokinin, ATP, or beta3-adrenergic receptors) and ion channels (e.g., TRPV1 or K) could be effective to suppress OAB. In the stress urinary incontinence condition, pharmacotherapies targeting the neurally mediated urethral continence reflex during stress conditions such as sneezing or coughing could be effective for increasing the outlet resistance. Therapeutic targets include adrenergic and serotonergic receptors in the spinal cord as well as adrenergic receptors at the urethral sphincter, which can enhance urethral reflex activity during stress conditions and increase baseline urethral pressure, respectively.
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Affiliation(s)
- Naoki Yoshimura
- Department of Urology, University of Pittsburgh School of Medicine, Suite 700 Kaufmann Medical Building, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA.
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26
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Beckett EAH, Ro S, Bayguinov Y, Sanders KM, Ward SM. Kit signaling is essential for development and maintenance of interstitial cells of Cajal and electrical rhythmicity in the embryonic gastrointestinal tract. Dev Dyn 2007; 236:60-72. [PMID: 16937373 DOI: 10.1002/dvdy.20929] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Interstitial cells of Cajal (ICC) are specialized cells in smooth muscle organs that generate and propagate pacemaker activity, receive inputs from motor neurons, and serve as mechanosensors. In the gastrointestinal tract, development and maintenance of the ICC phenotype have been linked to intracellular signaling via Kit, but its role in development of ICC during embryogenesis is controversial. Here we have studied the development of functional ICC-MY during the late gestational period in mice. Blocking Kit with a neutralizing antibody before and after development of spontaneous electrical activity (E17 to P0) caused loss of ICC-MY networks and pacemaker activity. ICC-MY and pacemaker activity developed normally in W/+ and W(V)/+ heterozygotes, but failed to develop between E17 to P0 in W/W(V) embryos with compromised Kit function. Muscles treated with Kit neutralizing antibody or the tyrosine kinase inhibitor, imatinib mesylate (STI571), from E17-P0 for 3 days caused loss of functionally developed ICC-MY networks, but ICC-MY and pacemaker activity recovered within 9 days after discontinuing treatment with neutralizing antibody or imatinib mesylate. These data suggest that Kit signaling is an important factor in lineage decision and in the development of functional ICC in late gestation. ICC-MY demonstrate significant plasticity in gastrointestinal tissues. Manipulation of the ICC phenotype might provide useful therapies in gastrointestinal disease where the Kit-positive cell population is either lost or amplified.
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Affiliation(s)
- Elizabeth A H Beckett
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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27
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Awumey EM, Howlett AC, Putney JW, Diz DI, Bukoski RD. Ca2+mobilization through dorsal root ganglion Ca2+-sensing receptor stably expressed in HEK293 cells. Am J Physiol Cell Physiol 2007; 292:C1895-905. [PMID: 17267550 DOI: 10.1152/ajpcell.00404.2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The rat dorsal root ganglion (DRG) Ca2+-sensing receptor (CaR) was stably expressed in-frame as an enhanced green fluorescent protein (EGFP) fusion protein in human embryonic kidney (HEK)293 cells, and is functionally linked to changes in intracellular Ca2+concentration ([Ca2+]i). RT-PCR analysis indicated the presence of the message for the DRG CaR cDNA. Western blot analysis of membrane proteins showed a doublet of 168–175 and 185 kDa, consistent with immature and mature forms of the CaR.EGFP fusion protein, respectively. Increasing extracellular [Ca2+] ([Ca2+]e) from 0.5 to 1 mM resulted in increases in [Ca2+]ilevels, which were blocked by 30 μM 2-aminoethyldiphenyl borate. [Ca2+]e-response studies indicate a Ca2+sensitivity with an EC50of 1.75 ± 0.10 mM. NPS R-467 and Gd3+activated the CaR. When [Ca2+]ewas successively raised from 0.25 to 4 mM, peak [Ca2+]i, attained with 0.5 mM, was reduced by ∼50%. Similar reductions were observed with repeated applications of 10 mM Ca2+, 1 and 10 μM NPS R-467, or 50 and 100 μM Gd3+, indicating desensitization of the response. Furthermore, Ca2+mobilization increased phosphorylated protein kinase C (PKC)α levels in the cells. However, the PKC activator, phorbol myristate acetate did not inhibit CaR-mediated Ca2+signaling. Rather, a spectrum of PKC inhibitors partially reduced peak responses to Cae2+. Treatment of cells with 100 nM PMA for 24 h, to downregulate PKC, reduced [Ca2+]itransients by 49.9 ± 5.2% (at 1 mM Ca2+) and 40.5 ± 6.5% (at 2 mM Ca2+), compared with controls. The findings suggest involvement of PKC in the pathway for Ca2+mobilization following CaR activation.
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Affiliation(s)
- Emmanuel M Awumey
- Cardiovascular Disease Research Program, Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George St., Durham, NC 27707, USA.
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28
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Abstract
The identification of defective structures in the ATP-binding cassette (ABC) transporters ABCG5 and ABCG8 in patients with sitosterolemia suggests that these two proteins are an apical sterol export pump promoting active efflux of cholesterol and plant sterols from enterocytes back into the intestinal lumen for excretion. The newly identified Niemann-Pick C1-like 1 (NPC1L1) protein is also expressed at the apical membrane of enterocytes and plays a crucial role in the ezetimibe-sensitive cholesterol absorption pathway. These findings indicate that cholesterol absorption is a multistep process that is regulated by multiple genes at the enterocyte level and that the efficiency of cholesterol absorption may be determined by the net effect between influx and efflux of intraluminal cholesterol molecules crossing the brush border membrane of the enterocyte. Combination therapy using cholesterol absorption (NPC1L1) inhibitor (ezetimibe) and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors (statins) provides a powerful novel strategy for the prevention and treatment of hypercholesterolemia.
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Affiliation(s)
- David Q-H Wang
- Department of Medicine, Liver Center and Gastroenterology Division, Beth Israel Deaconess Medical Center, Harvard Medical School and Harvard Digestive Diseases Center, Boston, Massachusetts 02115, USA.
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29
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Davy JA, Wang Z, Notter RH, Schwan AL. Synthesis of sulfur-containing glycerophospholipids. J Sulphur Chem 2007. [DOI: 10.1080/17415990601080166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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30
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Notter RH, Wang Z, Wang Z, Davy JA, Schwan AL. Synthesis and surface activity of diether-linked phosphoglycerols: Potential applications for exogenous lung surfactants. Bioorg Med Chem Lett 2007; 17:113-7. [PMID: 17055273 DOI: 10.1016/j.bmcl.2006.09.083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 09/24/2006] [Accepted: 09/27/2006] [Indexed: 10/24/2022]
Abstract
The synthesis of three phosphoglycerols is described, one of which contains the previously unknown phosphonoglycerol headgroup. The surface tension-lowering capabilities of synthetic lung surfactant mixtures containing the PG analogs were measured on the pulsating bubble surfactometer and compared to known controls. The PG-containing mixtures exhibited superior surface tension-lowering properties indicating the significant potential of these analogs as components in synthetic exogenous lung surfactants.
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Affiliation(s)
- Robert H Notter
- Department of Pediatrics, University of Rochester, Rochester, NY 14642, USA
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31
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Ohtsuki M, Taketomi Y, Arata S, Masuda S, Ishikawa Y, Ishii T, Takanezawa Y, Aoki J, Arai H, Yamamoto K, Kudo I, Murakami M. Transgenic expression of group V, but not group X, secreted phospholipase A2 in mice leads to neonatal lethality because of lung dysfunction. J Biol Chem 2006; 281:36420-33. [PMID: 17008322 DOI: 10.1074/jbc.m607975200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In an effort to elucidate the functions of secreted phospholipase A2 (sPLA2) enzymes in vivo, we generated transgenic (Tg) mice for group V sPLA2 (sPLA2-V) and group X sPLA2 (sPLA2-X), which act potently on phosphatidylcholine in vitro. We found that sPLA2-V Tg mice died in the neonatal period because of respiratory failure. The lungs of sPLA2-V Tg mice exhibited atelectasis with thickened alveolar walls and narrow air spaces, accompanied by infiltration of macrophages and only modest changes in eicosanoid levels. This severe pulmonary defect in sPLA2-V Tg mice was attributable to marked reduction of the lung surfactant phospholipids, phosphatidylcholine and phosphatidylglycerol. Given that the expression of sPLA2-V is greatly elevated in human lungs with severe inflammation, our present results raise the intriguing possibility that this isozyme may contribute to ongoing surfactant hydrolysis often observed in the lungs of patients with respiratory distress syndrome. In contrast, sPLA2-X Tg neonates displayed minimal abnormality of the respiratory tract with normal alveolar architecture and surfactant composition. This unexpected result was likely because sPLA2-X protein existed as an inactive zymogen in most tissues. The active form of sPLA2-X was detected in tissues with inflammatory granulation in sPLA2-X Tg mice. These results suggest that sPLA2-X mostly remains inactive under physiological conditions and that its proteolytic activation occurs during inflammation or other as yet unidentified circumstances in vivo.
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Affiliation(s)
- Mitsuhiro Ohtsuki
- Department of Health Chemistry, School of Pharmaceutical Sciences and Center for Biotechnology, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
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32
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Somasundaram C, Diz DI, Coleman T, Bukoski RD. Adventitial neuronal somata. J Vasc Res 2006; 43:278-88. [PMID: 16636576 DOI: 10.1159/000092765] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2005] [Accepted: 02/09/2006] [Indexed: 11/19/2022] Open
Abstract
Confocal analysis of the whole-mount rat mesenteric branch arteries (MBA) revealed nucleated structures with axonal processes which immunostained for calcitonin gene-related peptide (CGRP). Immunocytochemistry ruled out the possibility that these were immune elements (macrophages and mast or dendritic cells) in close proximity with nerve fibers. To test our hypothesis that beta-CGRP is expressed in the rat MBA, we performed RT-PCR using total RNA isolated from the mesenteric artery arcade and intron spanning primers designed to amplify 188 bp of the beta-CGRP and 333 bp of alpha-CGRP cDNA. The PCR yielded an amplicon of the predicted size which was cloned into the pCR 3.1 vector. DNA sequence analysis of the insert showed 100% homology with the beta-CGRP cDNA, indicating that mRNA encoding beta-CGRP is expressed in the vessel. To learn whether neuronal cell bodies are located in the adventitia of MBA, we performed a limited collagenase digestion of isolated segments and plated the resulting cells in Ham's F12 medium with 10% horse serum on polyornithine-coated cover glasses. The medium was replaced after 48 h with Ham's F12 nutrient mixture containing N2 supplement. This resulted in a mixed population of fibroblasts, a small number of smooth muscle cells and a subset of cells that sprouted axons and immunostained positively for neuronal cell adhesion molecule and CGRP antigens. Fibroblasts and smooth muscle cells did not label with these antibodies. These data demonstrate, for the first time, that a population of adventitial neuronal somata (termed ANNIES), possibly of sensory nerve origin, is located in small mesenteric arteries.
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MESH Headings
- Animals
- Antigens, CD/analysis
- Antigens, Differentiation/analysis
- Antigens, Differentiation, Myelomonocytic/analysis
- Base Sequence
- Calcitonin Gene-Related Peptide/analysis
- Calcitonin Gene-Related Peptide/genetics
- Cell Shape
- Cells, Cultured
- Connective Tissue Cells/chemistry
- Histocompatibility Antigens Class II/analysis
- Immunohistochemistry
- Male
- Mesenteric Arteries/chemistry
- Microscopy, Confocal
- Molecular Sequence Data
- Neural Cell Adhesion Molecules/analysis
- Neurons/chemistry
- RNA, Messenger/analysis
- Rats
- Rats, Wistar
- Receptors, Cell Surface/analysis
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
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Affiliation(s)
- Chandra Somasundaram
- Cardiovascular Disease Research Program, Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA.
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33
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Cohen JE, Fields RD. CaMKII inactivation by extracellular Ca(2+) depletion in dorsal root ganglion neurons. Cell Calcium 2006; 39:445-54. [PMID: 16519936 PMCID: PMC2365305 DOI: 10.1016/j.ceca.2006.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Revised: 11/21/2005] [Accepted: 01/21/2006] [Indexed: 10/24/2022]
Abstract
A mechanism by which Ca(2+)/CaM-dependent protein kinase (CaMKII) is autophosphorylated by changes in extracellular calcium in the absence of detectable changes in cytoplasmic [Ca(2+)] has been identified. We find that when the external Ca(2+) concentration ([Ca(2+)](O)) is lowered, Ca(2+) is released from intracellular stores to maintain a constant cytoplasmic Ca(2+) level, gradually depleting the endoplasmic Ca(2+) stores. Accompanying the store-depletion is a rapid decrease in CaMKII activity. Approximately 25% of the measured CaMKII autophosphorylation in DRG neurons in culture can be regulated by Ca(2+) flux from intracellular stores caused by manipulating [Ca(2+)](O), as shown by blocking refilling of store-operated Ca(2+)-channels with SK&F 96365, Ruthenium Red, and a partial block with Ni(2+). Blocking voltage-gated Ca(2+)-channels with either isradipine or SR 33805, had no effect on CaMKII autophosphorylation induced by restoring Ca(2+)(O) to normal after depleting the intracellular Ca(2+) stores. These results show that removal of Ca(2+)(O) has profound effects on intracellular Ca(2+) signaling and CaMKII autophosphorylation, in the absence of measurable changes in intracellular Ca(2+). These findings have wide-ranging significance, because [Ca(2+)](O) is manipulated in many experimental studies. Moreover, this explanation for the paradoxical changes in CaMKII phosphorylation in response to manipulating [Ca(2+)](O) provides a possible mechanism linking activity-dependent depletion of Ca(2+) from the synaptic cleft to a protein kinase regulating many neuronal properties.
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Affiliation(s)
| | - R. Douglas Fields
- Corresponding author. Tel.: +1 301 480 3209; fax: +1 301 496 9630. E-mail address: (R.D. Fields)
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Ullah MS, Davies AJ, Halestrap AP. The plasma membrane lactate transporter MCT4, but not MCT1, is up-regulated by hypoxia through a HIF-1alpha-dependent mechanism. J Biol Chem 2006; 281:9030-7. [PMID: 16452478 DOI: 10.1074/jbc.m511397200] [Citation(s) in RCA: 668] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The monocarboxylate transporter MCT4 mediates lactic acid efflux from most tissues that are dependent on glycolysis for their ATP production. Here we demonstrate that expression of MCT4 mRNA and protein was increased >3-fold by a 48-h exposure to 1% O(2), whereas MCT1 expression was not increased. The effect was mimicked by CoCl(2) (50 microm), suggesting transcriptional regulation by hypoxia-inducible factor 1alpha (HIF-1alpha). The predicted promoters for human MCT1, MCT2, and MCT4 were cloned into the pGL3 vector and shown to be active (luciferase luminescence) under basal conditions. Only the MCT4 promoter was activated (>2-fold) by hypoxia. No response was found in cells lacking HIF-1alpha. Four potential hypoxia-response elements were identified, but deletion analysis implicated only two in the hypoxia response. These were just upstream from the transcription start site and also found in the mouse MCT4 promoter. Mutation of site 2 totally abolished the hypoxic response, whereas mutation of site 1 only reduced the response. Gel-shift analysis demonstrated that nuclear extracts of hypoxic but not normoxic HeLa cells contained two transcription factors that bound to DNA probes containing these hypoxia-response elements. The major shifted band was abolished by mutation of site 2, and supershift analysis confirmed that HIF-1alpha bound to this site. Binding of the second factor was abolished by mutation of site 1. We conclude that MCT4, like other glycolytic enzymes, is up-regulated by hypoxia through a HIF-1alpha-mediated mechanism. This adaptive response allows the increased lactic acid produced during hypoxia to be rapidly lost from the cell.
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Affiliation(s)
- Mohammed S Ullah
- Department of Biochemistry, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, United Kingdom
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Wang HH, Wang DQH. Reduced susceptibility to cholesterol gallstone formation in mice that do not produce apolipoprotein B48 in the intestine. Hepatology 2005; 42:894-904. [PMID: 16175613 DOI: 10.1002/hep.20867] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
It has been found that polymorphisms in the apolipoprotein (APO)-B gene are associated with cholesterol gallstones in humans. We hypothesized that APO-B plays a major regulatory role in the response of biliary cholesterol secretion to high dietary cholesterol and contributes to cholesterol gallstone formation. In the present study, we investigated whether lack of expression of intestinal Apob48 or Apob100 reduces susceptibility to cholesterol gallstones by decreasing intestinal absorption and biliary secretion of cholesterol in male mice homozygous for an "APO-B48 only" allele (Apob(48/48)), an "APO-B100 only" allele (Apob(100/100)), or a wild-type APO-B allele (Apob+/+) before and during an 8-week lithogenic diet. We found that cholesterol absorption was significantly decreased as a result of the APO-B48 deficiency in Apob(100/100) mice compared with wild-type and Apob(48/48) mice, regardless of whether chow or the lithogenic diet was administered. Consequently, hepatic cholesterol synthesis was significantly increased in Apob(100/100) mice compared with wild-type and Apob(48/48) mice. On chow, the APO-B100 deficiency in Apob(48/48) mice with reduced plasma levels of LDL/VLDL--but not HDL cholesterol--induced relative hyposecretion of biliary bile salts and phospholipids accompanying normal biliary cholesterol secretion. Compared with Apob(48/48) and wild-type mice, lithogenic diet-fed Apob(100/100) mice displayed significantly lower secretion rates of biliary cholesterol, but not phospholipid or bile salts, which results in significant decreases in prevalence rates, numbers, and sizes of gallstones. In conclusion, absence of expression of intestinal Apob48, but not Apob100, reduces biliary cholesterol secretion and cholelithogenesis, possibly by decreasing intestinal absorption and hepatic bioavailability.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 5
- ATP Binding Cassette Transporter, Subfamily G, Member 8
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Animals
- Apolipoprotein B-100
- Apolipoprotein B-48
- Apolipoproteins B/genetics
- Apolipoproteins B/metabolism
- Bile Acids and Salts/biosynthesis
- Bile Acids and Salts/metabolism
- Cholesterol, Dietary/blood
- Cholesterol, Dietary/pharmacokinetics
- Disease Susceptibility
- Female
- Gallstones/epidemiology
- Gallstones/genetics
- Gallstones/metabolism
- Intestinal Absorption
- Intestine, Small/metabolism
- Lipoproteins/genetics
- Lipoproteins/metabolism
- Liver/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Prevalence
- RNA, Messenger/analysis
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Affiliation(s)
- Helen H Wang
- Department of Medicine, Liver Center and Gastroenterology Division, Beth Israel Deaconess Medical Center, Harvard Medical School and Harvard Digestive Diseases Center, Boston, MA 02215, USA
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Wang J, Fan J, Laschinger C, Arora PD, Kapus A, Seth A, McCulloch CA. Smooth muscle actin determines mechanical force-induced p38 activation. J Biol Chem 2004; 280:7273-84. [PMID: 15591055 DOI: 10.1074/jbc.m410819200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The mitogen-activated protein kinase p38 is activated by mechanical force, but the cellular elements that mediate force-induced p38 phosphorylation are not defined. As alpha-smooth muscle actin (SMA) is an actin isoform associated with force generation in fibroblasts, we asked if SMA participates in the activation of p38 by force. Tensile forces (0.65 pn/mum(2)) generated by magnetic fields were applied to collagen-coated magnetite beads bound to Rat-2 cells. Immunoblotting showed that p38alpha was the predominant p38 isoform. Analysis of bead-associated proteins demonstrated that SMA enrichment of collagen receptor complexes required the alpha2beta1 integrin. SMA was present almost entirely as filaments. Swinholide depolymerized SMA filaments and blocked force-induced p38 phosphorylation and force-induced increases of SMA. Knockdown of SMA (70% reduction) using RNA interference did not affect beta-actin but inhibited force-induced p38 phosphorylation by 50%. Inhibition of Rho kinase blocked SMA filament assembly, force-induced increases of SMA, and force-induced p38 activation. Force application increased SMA content and enhanced the association of phosphorylated p38 with SMA filaments. Blockade of p38 phosphorylation by SB203586 abrogated force-induced increases of SMA. In cells transfected with SMA promoter-beta-galactosidase fusion constructs, co-transfection with constitutively active p38 or MKK6 increased SMA promoter activity by 2.5-3-fold. Dominant negative p38 blocked force-induced activation of the SMA promoter. In SMA negative cells, there was no force-induced p38 phosphorylation. We conclude that force-induced p38 phosphorylation is dependent on an SMA filament-dependent pathway that uses a feed-forward amplification loop to synergize force-induced SMA expression with p38 activation.
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Affiliation(s)
- Jiaxu Wang
- Canadian Institutes of Health, Group in Matrix Dynamics, Faculty of Dentistry, University of Toronto, Ontario, Canada
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Bukoski RD. Linkage of Na(+) and Ca(2+) balance: evidence that Na(+) retention preserves Ca(2+) balance and limits bone wasting. J Hypertens 2004; 22:683-5. [PMID: 15126906 DOI: 10.1097/00004872-200404000-00007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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38
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Chang Y, Wang Z, Notter RH, Wang Z, Qu L, Schwan AL. Synthesis and interfacial behavior of sulfur-containing analogs of lung surfactant dipalmitoyl phosphatidylcholine. Bioorg Med Chem Lett 2004; 14:5983-6. [PMID: 15546713 DOI: 10.1016/j.bmcl.2004.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 09/28/2004] [Accepted: 10/02/2004] [Indexed: 11/19/2022]
Abstract
Synthesis methods and initial surface property characterizations are reported for two sulfur-containing phosphonolipids related structurally to dipalmitoyl phosphatidylcholine (DPPC), the major lung surfactant glycerophospholipid. Sulfur linkages in these compounds affect molecular interactions relative to ester linkages, and are structurally resistant to cleavage by phospholipases. The SO2-linked analog synthesized here had increased adsorption and improved film respreading compared to DPPC, while reaching very low surface tensions (1 N/m) in cycled interfacial films on both the Wilhelmy balance and the pulsating bubble surfactometer. This compound appears to have potential utility as a component in future phospholipase-resistant synthetic exogenous surfactants for treating clinical forms of inflammatory lung injury.
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Affiliation(s)
- Yusuo Chang
- Department of Pediatrics, University of Rochester, Rochester, NY 14642, USA
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Wang DQH, Schmitz F, Kopin AS, Carey MC. Targeted disruption of the murine cholecystokinin-1 receptor promotes intestinal cholesterol absorption and susceptibility to cholesterol cholelithiasis. J Clin Invest 2004; 114:521-8. [PMID: 15314689 PMCID: PMC503765 DOI: 10.1172/jci16801] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2002] [Accepted: 06/29/2004] [Indexed: 01/09/2023] Open
Abstract
Cholecystokinin (CCK) modulates contractility of the gallbladder, the sphincter of Oddi, and the stomach. These effects are mediated through activation of gastrointestinal smooth muscle as well as enteric neuron CCK-1 receptors (CCK-1Rs). To investigate the potential physiological and pathophysiological functions linked to CCK-1R-mediated signaling, we compared male WT and CCK-1R-deficient mice (129/SvEv). After 12 weeks on either a standard mouse chow or a lithogenic diet (containing 1% cholesterol, 0.5% cholic acid, and 15% dairy fat), small-intestinal transit time, intestinal cholesterol absorption, biliary cholesterol secretion, and cholesterol gallstone prevalence were compared in knockout versus WT animals. Analysis of mice on either the chow or the lithogenic diet revealed that CCK-1R(-/-) animals had larger gallbladder volumes (predisposing to bile stasis), significant retardation of small-intestinal transit times (resulting in increased cholesterol absorption), and increased biliary cholesterol secretion rates. The elevation in bile cholesterol, coupled with a tendency toward gallbladder stasis (due to the absence of CCK-induced contraction), facilitates nucleation, growth, and agglomeration of cholesterol monohydrate crystals; this sequence of events in turn results in a significantly higher prevalence of cholesterol gallstones in the CCK-1R-null mice.
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Affiliation(s)
- David Q-H Wang
- Department of Medicine, Liver Center and Gastroenterology Division, Beth Israel Deaconess Medical Center, Boston, MA, USA
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Sarkis A, Lopez B, Roman RJ. Role of 20-hydroxyeicosatetraenoic acid and epoxyeicosatrienoic acids in hypertension. Curr Opin Nephrol Hypertens 2004; 13:205-14. [PMID: 15202615 DOI: 10.1097/00041552-200403000-00009] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Cytochrome P-450 metabolites of arachidonic acid have been reported to play an important role in the control of renal function and vascular tone, and in the long-term control of arterial pressure. In this regard, 20-hydroxyeicosatetraenoic acid is a potent vasoconstrictor that inhibits sodium reabsorption in the kidney. Epoxyeicosatrienoic acids are endothelium-derived relaxing factors that hyperpolarize vascular smooth muscle cells and also promote sodium excretion in the kidney. RECENT FINDINGS Studies have demonstrated that the expression of cytochrome P-450 enzymes and the synthesis of 20-hydroxyeicosatetraenoic acid and epoxyeicosatrienoic acids in the kidney and peripheral vasculature are altered in many genetic and experimental models of hypertension. The production of these compounds is altered following exposure to high-salt or high-fat diets, in hepatorenal syndrome, in diabetes and in patients with toxemia of pregnancy. However, the functional significance of changes in the formation of 20-hydroxyeicosatetraenoic acid and epoxyeicosatrienoic acids in the pathogenesis of hypertension are just being uncovered. SUMMARY This review summarizes recent findings that address the issue of whether cytochrome P-450 metabolites of arachidonic acid play an important role in the regulation of renal tubular and peripheral vascular function and contribute to the pathogenesis of hypertension.
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Affiliation(s)
- Albert Sarkis
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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