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Abstract
Members of the transient receptor potential (TRP) channels that are expressed in the kidney have gained prominence in recent years following discoveries of their role in maintaining the integrity of the filtration barrier, regulating tubular reabsorption of Ca2+ and Mg2+, and sensing osmotic stimuli. Furthermore, evidence has linked mutations in TRP channels to kidney disease pathophysiological mechanisms, including focal segmental glomerulosclerosis, disturbances in Mg2+ homeostasis, and polycystic kidney disease. Several subtypes of TRP channels are expressed in the renal vasculature, from preglomerular arteries and arterioles to the descending vasa recta. Although investigations on the physiological and pathological significance of renal vascular TRP channels are sparse, studies on isolated vessels and cells have suggested their involvement in renal vasoregulation. Renal blood flow (RBF) is an essential determinant of kidney function, including glomerular filtration, water and solute reabsorption, and waste product excretion. Functional alterations in ion channels that are expressed in the endothelium and smooth muscle of renal vessels can modulate renal vascular resistance, arterial pressure, and RBF. Hence, renal vascular TRP channels are potential therapeutic targets for the treatment of kidney disease. This review summarizes the current knowledge of TRP channel expression in renal vasculature and their role in controlling kidney function in health and disease. TRP channels are widely distributed in mammalian kidneys in glomerular, tubular, and vascular cells. TRPC and TRPV channels are functionally expressed in afferent arterioles. TRPC4 may regulate Ca2+ signaling in the descending vasa recta. Smooth muscle, endothelial, and pericyte TRP channels may participate in signal transduction mechanisms. TRP channels underlie renal autoregulation and regional kidney perfusion in health and disease.
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Affiliation(s)
- Praghalathan Kanthakumar
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Adebowale Adebiyi
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
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Chaudhari S, Mallet RT, Shotorbani PY, Tao Y, Ma R. Store-operated calcium entry: Pivotal roles in renal physiology and pathophysiology. Exp Biol Med (Maywood) 2020; 246:305-316. [PMID: 33249888 DOI: 10.1177/1535370220975207] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Research conducted over the last two decades has dramatically advanced the understanding of store-operated calcium channels (SOCC) and their impact on renal function. Kidneys contain many types of cells, including those specialized for glomerular filtration (fenestrated capillary endothelium, podocytes), water and solute transport (tubular epithelium), and regulation of glomerular filtration and renal blood flow (vascular smooth muscle cells, mesangial cells). The highly integrated function of these myriad cells effects renal control of blood pressure, extracellular fluid volume and osmolality, electrolyte balance, and acid-base homeostasis. Many of these cells are regulated by Ca2+ signaling. Recent evidence demonstrates that SOCCs are major Ca2+ entry portals in several renal cell types. SOCC is activated by depletion of Ca2+ stores in the sarco/endoplasmic reticulum, which communicates with plasma membrane SOCC via the Ca2+ sensor Stromal Interaction Molecule 1 (STIM1). Orai1 is recognized as the main pore-forming subunit of SOCC in the plasma membrane. Orai proteins alone can form highly Ca2+ selective SOCC channels. Also, members of the Transient Receptor Potential Canonical (TRPC) channel family are proposed to form heteromeric complexes with Orai1 subunits, forming SOCC with low Ca2+ selectivity. Recently, Ca2+ entry through SOCC, known as store-operated Ca2+ entry (SOCE), was identified in glomerular mesangial cells, tubular epithelium, and renovascular smooth muscle cells. The physiological and pathological relevance and the characterization of SOCC complexes in those cells are still unclear. In this review, we summarize the current knowledge of SOCC and their roles in renal glomerular, tubular and vascular cells, including studies from our laboratory, emphasizing SOCE regulation of fibrotic protein deposition. Understanding the diverse roles of SOCE in different renal cell types is essential, as SOCC and its signaling pathways are emerging targets for treatment of SOCE-related diseases.
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Affiliation(s)
- Sarika Chaudhari
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Robert T Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Parisa Y Shotorbani
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Yu Tao
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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Abstract
Microcirculation is the generic name for the finest level of the circulatory system and consists of arteriolar and venular networks located upstream and downstream of capillaries, respectively. Anatomically arterioles are surrounded by a monolayer of spindle-shaped smooth muscle cells (myocytes), while terminal branches of precapillary arterioles, capillaries and all sections of postcapillary venules are surrounded by a monolayer of morphologically different perivascular cells (pericytes). Pericytes are essential components of the microvascular vessel wall. Wrapped around endothelial cells, they occupy a strategic position at the interface between the circulating blood and the interstitial space. There are physiological differences in the responses of pericytes and myocytes to vasoactive molecules, which suggest that these two types of vascular cells could have different functional roles in the regulation of local blood flow within the same microvascular bed. Also, pericytes may play different roles in different microcirculatory beds to meet the characteristics of individual organs. Contractile activity of pericytes and myocytes is controlled by changes of cytosolic free Ca2+concentration. In this chapter, we attempt to summarize the results in the field of Ca2+ signalling in pericytes especially in light of their contractile roles in different tissues and organs. We investigate the literature and describe our results regarding sources of Ca2+, relative importance and mechanisms of Ca2+ release and Ca2+ entry in control of the spatio-temporal characteristics of the Ca2+ signals in pericytes, where possible Ca2+ signalling and contractile responses in pericytes are compared to those of myocytes.
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Emerging Roles of Diacylglycerol-Sensitive TRPC4/5 Channels. Cells 2018; 7:cells7110218. [PMID: 30463370 PMCID: PMC6262340 DOI: 10.3390/cells7110218] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 11/15/2018] [Accepted: 11/16/2018] [Indexed: 12/31/2022] Open
Abstract
Transient receptor potential classical or canonical 4 (TRPC4) and TRPC5 channels are members of the classical or canonical transient receptor potential (TRPC) channel family of non-selective cation channels. TRPC4 and TRPC5 channels are widely accepted as receptor-operated cation channels that are activated in a phospholipase C-dependent manner, following the Gq/11 protein-coupled receptor activation. However, their precise activation mechanism has remained largely elusive for a long time, as the TRPC4 and TRPC5 channels were considered as being insensitive to the second messenger diacylglycerol (DAG) in contrast to the other TRPC channels. Recent findings indicate that the C-terminal interactions with the scaffolding proteins Na+/H+ exchanger regulatory factor 1 and 2 (NHERF1 and NHERF2) dynamically regulate the DAG sensitivity of the TRPC4 and TRPC5 channels. Interestingly, the C-terminal NHERF binding suppresses, while the dissociation of NHERF enables, the DAG sensitivity of the TRPC4 and TRPC5 channels. This leads to the assumption that all of the TRPC channels are DAG sensitive. The identification of the regulatory function of the NHERF proteins in the TRPC4/5-NHERF protein complex offers a new starting point to get deeper insights into the molecular basis of TRPC channel activation. Future studies will have to unravel the physiological and pathophysiological functions of this multi-protein channel complex.
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Wei L, Du Y, Jia L, Ma X, Chen Z, Lu J, Tian L, Duan Z, Dong F, Lv Z, Yao G, Fu R, Wang L. Therapeutic Effects of FK506 on IgA Nephropathy Rat. Kidney Blood Press Res 2017; 42:983-998. [PMID: 29179182 DOI: 10.1159/000485346] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 11/16/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS FK506 is an immunosuppressive drug and a calcineurin inhibitor that has been widely used in kidney disease in recent years. FK506 shows a wide range of biological and pharmaceutical effects; however, the mechanism of its anti- proliferative effect has not been well elucidated. An IgA nephropathy (IgAN) model was used to generate a mesangial cell proliferation model. This study aims to examine the effect of FK506 on IgAN rats and the underlying mechanisms. METHODS Hematuria, proteinuria and renal function were measured. To observe the pathological conditions, we performed HE (hematoxylin - eosin) and PAS (periodic acid - schiff) staining. Transcription and protein expression levels were detected by qRT - PCR (quantitative real-time polymerase chain reaction) and Wb (western blotting). The location and semi-quantitative expression levels of TRPCs, CaN (Calcineurin) and α-SMA were examined by IHC (Immunohistochemical staining). RESULTS We found that FK506 could improve hematuria, proteinuria and renal function, especially in the HF (high-dose FK506) groups. Renal pathological changes were ameliorated in the treatment groups. FK506 could significantly decrease TRPCs, CaN, phosphorylation of ERK1/2 and α-SMA expression. CONCLUSION Taken together, these results suggest that the therapeutic effect of FK506 on IgAN might be partially associated with the down-regulated expression of TRPC channels, CaN and phosphorylation of ERK1/2.
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Affiliation(s)
- Linting Wei
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yan Du
- Department of Nephrology, the First Affiliated Hospital of Xi'an Medical University, Xi'an, China
| | - Lining Jia
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiaotao Ma
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Zhao Chen
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Jiamei Lu
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Lifang Tian
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Zhaoyang Duan
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Fengming Dong
- Department of Nephrology, Jiangsu Taizhou People's Hospital, Taizhou, China
| | - Zhian Lv
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Ganglian Yao
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Rongguo Fu
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Li Wang
- Department of Nephrology, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
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Dynamic NHERF interaction with TRPC4/5 proteins is required for channel gating by diacylglycerol. Proc Natl Acad Sci U S A 2016; 114:E37-E46. [PMID: 27994151 DOI: 10.1073/pnas.1612263114] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The activation mechanism of the classical transient receptor potential channels TRPC4 and -5 via the Gq/11 protein-phospholipase C (PLC) signaling pathway has remained elusive so far. In contrast to all other TRPC channels, the PLC product diacylglycerol (DAG) is not sufficient for channel activation, whereas TRPC4/5 channel activity is potentiated by phosphatidylinositol 4,5-bisphosphate (PIP2) depletion. As a characteristic structural feature, TRPC4/5 channels contain a C-terminal PDZ-binding motif allowing for binding of the scaffolding proteins Na+/H+ exchanger regulatory factor (NHERF) 1 and 2. PKC inhibition or the exchange of threonine for alanine in the C-terminal PDZ-binding motif conferred DAG sensitivity to the channel. Altogether, we present a DAG-mediated activation mechanism for TRPC4/5 channels tightly regulated by NHERF1/2 interaction. PIP2 depletion evokes a C-terminal conformational change of TRPC5 proteins leading to dynamic dissociation of NHERF1/2 from the C terminus of TRPC5 as a prerequisite for DAG sensitivity. We show that NHERF proteins are direct regulators of ion channel activity and that DAG sensitivity is a distinctive hallmark of TRPC channels.
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Constantin B. Role of Scaffolding Proteins in the Regulation of TRPC-Dependent Calcium Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:379-403. [PMID: 27161237 DOI: 10.1007/978-3-319-26974-0_16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
Plasma membrane ion channels, and in particular TRPC channels need a specific membrane environment and association with scaffolding, signaling, and cytoskeleton proteins in order to play their important functional role. The molecular composition of TRPC channels is an important factor in determining channel activation mechanisms. TRPC proteins are incorporated in macromolecular complexes including several key Ca(2 +) signaling proteins as well as proteins involved in vesicle trafficking, cytoskeletal interactions, and scaffolding. Evidence has been provided for association of TRPC with calmodulin (CaM), IP3R, PMCA, Gq/11, RhoA, and a variety of scaffolding proteins. The interaction between TRPC channels with adaptor proteins, determines their mode of regulation as well as their cellular localization and function. Adaptor proteins do not display any enzymatic activity but act as scaffold for the building of signaling complexes. The scaffolding proteins are involved in the assembling of these Ca(2+) signaling complexes, the correct sub-cellular localization of protein partners, and the regulation of the TRPC channelosome. In particular, these proteins, via their multiple protein-protein interaction motifs, can interact with various ion channels involved in the transmembrane potential, and membrane excitability. Scaffolding proteins are key components for the functional organization of TRPC channelosomes that serves as a platform regulating slow Ca(2+) entry, spatially and temporally controlled [Ca(2+)]i signals and Ca(2+) -dependent cellular functions.
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Affiliation(s)
- Bruno Constantin
- Laboratory STIM, ERL-7368 CNRS-Université de Poitiers, 1, rue Georges Bonnet, Bat. B36, Pôle Biologie-Santé, 86000, Poitiers, France.
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Ren A, Moon C, Zhang W, Sinha C, Yarlagadda S, Arora K, Wang X, Yue J, Parthasarathi K, Heil-Chapdelaine R, Tigyi G, Naren AP. Asymmetrical macromolecular complex formation of lysophosphatidic acid receptor 2 (LPA2) mediates gradient sensing in fibroblasts. J Biol Chem 2014; 289:35757-69. [PMID: 25542932 DOI: 10.1074/jbc.m114.595512] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chemotactic migration of fibroblasts toward growth factors relies on their capacity to sense minute extracellular gradients and respond to spatially confined receptor-mediated signals. Currently, mechanisms underlying the gradient sensing of fibroblasts remain poorly understood. Using single-particle tracking methodology, we determined that a lysophosphatidic acid (LPA) gradient induces a spatiotemporally restricted decrease in the mobility of LPA receptor 2 (LPA2) on chemotactic fibroblasts. The onset of decreased LPA2 mobility correlates to the spatial recruitment and coupling to LPA2-interacting proteins that anchor the complex to the cytoskeleton. These localized PDZ motif-mediated macromolecular complexes of LPA2 trigger a Ca(2+) puff gradient that governs gradient sensing and directional migration in response to LPA. Disruption of the PDZ motif-mediated assembly of the macromolecular complex of LPA2 disorganizes the gradient of Ca(2+) puffs, disrupts gradient sensing, and reduces the directional migration of fibroblasts toward LPA. Our findings illustrate that the asymmetric macromolecular complex formation of chemoattractant receptors mediates gradient sensing and provides a new mechanistic basis for models to describe gradient sensing of fibroblasts.
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Affiliation(s)
- Aixia Ren
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Changsuk Moon
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, the Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Weiqiang Zhang
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, the Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee 38103
| | - Chandrima Sinha
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Sunitha Yarlagadda
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, the Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Kavisha Arora
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, the Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Xusheng Wang
- the Department of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, and
| | - Junming Yue
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Kaushik Parthasarathi
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | | | - Gabor Tigyi
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Anjaparavanda P Naren
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, the Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229,
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Burdyga T, Borysova L. Calcium signalling in pericytes. J Vasc Res 2014; 51:190-9. [PMID: 24903335 DOI: 10.1159/000362687] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 04/06/2014] [Indexed: 11/19/2022] Open
Abstract
Recent advances in pericyte research have contributed to our understanding of the physiology and pathophysiology of microvessels. The microvasculature consists of arteriolar and venular networks located upstream and downstream of the capillaries. Arterioles are surrounded by a monolayer of spindle-shaped myocytes, while terminal branches of precapillary arterioles, capillaries and all sections of postcapillary venules are encircled by a monolayer of morphologically diverse pericytes. There are physiological differences in the response of pericytes and myocytes to vasoactive molecules, suggesting that these two vascular cell types could have different functional roles in the regulation of local blood flow. The contractile activity of pericytes and myocytes is controlled by changes of cytosolic free Ca(2+) concentration. In this short review, we summarize our results and those of other authors on the contractility of pericytes and their Ca(2+) signalling. We describe results regarding sources of Ca(2+) and mechanisms of Ca(2+) release and Ca(2+) entry in control of the spatiotemporal characteristics of the Ca(2+) signals in pericytes.
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Affiliation(s)
- Theodor Burdyga
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
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10
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Abstract
TRPC4 proteins comprise six transmembrane domains, a putative pore-forming region, and an intracellularly located amino- and carboxy-terminus. Among eleven splice variants identified so far, TRPC4α and TRPC4β are the most abundantly expressed and functionally characterized. TRPC4 is expressed in various organs and cell types including the soma and dendrites of numerous types of neurons; the cardiovascular system including endothelial, smooth muscle, and cardiac cells; myometrial and skeletal muscle cells; kidney; and immune cells such as mast cells. Both recombinant and native TRPC4-containing channels differ tremendously in their permeability and other biophysical properties, pharmacological modulation, and mode of activation depending on the cellular environment. They vary from inwardly rectifying store-operated channels with a high Ca(2+) selectivity to non-store-operated channels predominantly carrying Na(+) and activated by Gαq- and/or Gαi-coupled receptors with a complex U-shaped current-voltage relationship. Thus, individual TRPC4-containing channels contribute to agonist-induced Ca(2+) entry directly or indirectly via depolarization and activation of voltage-gated Ca(2+) channels. The differences in channel properties may arise from variations in the composition of the channel complexes, in the specific regulatory pathways in the corresponding cell system, and/or in the expression pattern of interaction partners which comprise other TRPC proteins to form heteromultimeric channels. Additional interaction partners of TRPC4 that can mediate the activity of TRPC4-containing channels include (1) scaffolding proteins (e.g., NHERF) that may mediate interactions with signaling molecules in or in close vicinity to the plasma membrane such as Gα proteins or phospholipase C and with the cytoskeleton, (2) proteins in specific membrane microdomains (e.g., caveolin-1), or (3) proteins on cellular organelles (e.g., Stim1). The diversity of TRPC4-containing channels hampers the development of specific agonists or antagonists, but recently, ML204 was identified as a blocker of both recombinant and endogenous TRPC4-containing channels with an IC50 in the lower micromolar range that lacks activity on most voltage-gated channels and other TRPs except TRPC5 and TRPC3. Lanthanides are specific activators of heterologously expressed TRPC4- and TRPC5-containing channels but can block individual native TRPC4-containing channels. The biological relevance of TRPC4-containing channels was demonstrated by knockdown of TRPC4 expression in numerous native systems including gene expression, cell differentiation and proliferation, formation of myotubes, and axonal regeneration. Studies of TRPC4 single and TRPC compound knockout mice uncovered their role for the regulation of vascular tone, endothelial permeability, gastrointestinal contractility and motility, neurotransmitter release, and social exploratory behavior as well as for excitotoxicity and epileptogenesis. Recently, a single-nucleotide polymorphism (SNP) in the Trpc4 gene was associated with a reduced risk for experience of myocardial infarction.
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Affiliation(s)
- Marc Freichel
- Pharmakologisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 366, 69120, Heidelberg, Germany,
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11
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Abstract
TRP channels constitute a large superfamily of cation channel forming proteins, all related to the gene product of the transient receptor potential (trp) locus in Drosophila. In mammals, 28 different TRP channel genes have been identified, which exhibit a large variety of functional properties and play diverse cellular and physiological roles. In this article, we provide a brief and systematic summary of expression, function, and (patho)physiological role of the mammalian TRP channels.
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Affiliation(s)
- Maarten Gees
- Laboratory Ion Channel Research and TRP Research Platform Leuven (TRPLe), KU Leuven, Campus Gasthuisberg, Leuven, Belgium
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Moccia F, Berra-Romani R, Tanzi F. Update on vascular endothelial Ca 2+ signalling: A tale of ion channels, pumps and transporters. World J Biol Chem 2012; 3:127-58. [PMID: 22905291 PMCID: PMC3421132 DOI: 10.4331/wjbc.v3.i7.127] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 07/04/2012] [Accepted: 07/11/2012] [Indexed: 02/05/2023] Open
Abstract
A monolayer of endothelial cells (ECs) lines the lumen of blood vessels and forms a multifunctional transducing organ that mediates a plethora of cardiovascular processes. The activation of ECs from as state of quiescence is, therefore, regarded among the early events leading to the onset and progression of potentially lethal diseases, such as hypertension, myocardial infarction, brain stroke, and tumor. Intracellular Ca2+ signals have long been know to play a central role in the complex network of signaling pathways regulating the endothelial functions. Notably, recent work has outlined how any change in the pattern of expression of endothelial channels, transporters and pumps involved in the modulation of intracellular Ca2+ levels may dramatically affect whole body homeostasis. Vascular ECs may react to both mechanical and chemical stimuli by generating a variety of intracellular Ca2+ signals, ranging from brief, localized Ca2+ pulses to prolonged Ca2+ oscillations engulfing the whole cytoplasm. The well-defined spatiotemporal profile of the subcellular Ca2+ signals elicited in ECs by specific extracellular inputs depends on the interaction between Ca2+ releasing channels, which are located both on the plasma membrane and in a number of intracellular organelles, and Ca2+ removing systems. The present article aims to summarize both the past and recent literature in the field to provide a clear-cut picture of our current knowledge on the molecular nature and the role played by the components of the Ca2+ machinery in vascular ECs under both physiological and pathological conditions.
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Affiliation(s)
- Francesco Moccia
- Francesco Moccia, Franco Tanzi, Department of Biology and Biotechnologies "Lazzaro Spallanzani", Laboratory of Physiology, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy
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14
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Ritter SL, Hall RA. Fine-tuning of GPCR activity by receptor-interacting proteins. Nat Rev Mol Cell Biol 2009; 10:819-30. [PMID: 19935667 DOI: 10.1038/nrm2803] [Citation(s) in RCA: 362] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors (GPCRs) mediate physiological responses to various ligands, such as hormones, neurotransmitters and sensory stimuli. The signalling and trafficking properties of GPCRs are often highly malleable depending on the cellular context. Such fine-tuning of GPCR function can be attributed in many cases to receptor-interacting proteins that are differentially expressed in distinct cell types. In some cases these GPCR-interacting partners directly mediate receptor signalling, whereas in other cases they act mainly as scaffolds to modulate G protein-mediated signalling. Furthermore, GPCR-interacting proteins can have a big impact on the regulation of GPCR trafficking, localization and/or pharmacological properties.
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Affiliation(s)
- Stefanie L Ritter
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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15
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Navar LG, Arendshorst WJ, Pallone TL, Inscho EW, Imig JD, Bell PD. The Renal Microcirculation. Compr Physiol 2008. [DOI: 10.1002/cphy.cp020413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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16
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Kruger WA, Yun CC, Monteith GR, Poronnik P. Muscarinic-induced recruitment of plasma membrane Ca2+-ATPase involves PSD-95/Dlg/Zo-1-mediated interactions. J Biol Chem 2008; 284:1820-30. [PMID: 19017653 DOI: 10.1074/jbc.m804590200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Efflux of cytosolic Ca2+ mediated by plasma membrane Ca2+-ATPases (PMCA) plays a key role in fine tuning the magnitude and duration of Ca2+ signaling following activation of G-protein-coupled receptors. However, the molecular mechanisms that underpin the trafficking of PMCA to the membrane during Ca2+ signaling remain largely unexplored in native cell models. One potential mechanism for the recruitment of proteins to the plasma membrane involves PDZ interactions. In this context, we investigated the role of PMCA interactions with the Na+/H+ exchanger regulatory factor 2 (NHERF-2) during muscarinic-induced Ca2+ mobilization in the HT-29 epithelial cell line. GST pull-downs in HT-29 cell lysates showed that the PDZ2 module of NHERF-2 bound to the PDZ binding motif on the C terminus of PMCA. Co-immunoprecipitations confirmed that PMCA1b and NHERF-2 associated under normal conditions in HT-29 cells. Cell surface biotinylations revealed significant increases in membrane-associated NHERF-2 and PMCA within 60 s following muscarinic activation, accompanied by increased association of the two proteins as seen by confocal microscopy. The recruitment of NHERF-2 to the membrane preceded that of PMCA, suggesting that NHERF-2 was involved in nucleating an efflux complex at the membrane. The muscarinic-mediated translocation of PMCA was abolished when NHERF-2 was silenced, and the rate of relative Ca2+ efflux was also reduced. These experiments also uncovered a NHERF-2-independent PMCA retrieval mechanism. Our findings describe rapid agonist-induced translocation of PMCA in a native cell model and suggest that NHERF-2 plays a key role in scaffolding and maintaining PMCA at the cell membrane.
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Affiliation(s)
- Wade A Kruger
- School of Biomedical Sciences and School of Pharmacy, The University of Queensland, Brisbane QLD 4072, Australia
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Cao C, Payne K, Lee-Kwon W, Zhang Z, Lim SW, Hamlyn J, Blaustein MP, Kwon HM, Pallone TL. Chronic ouabain treatment induces vasa recta endothelial dysfunction in the rat. Am J Physiol Renal Physiol 2008; 296:F98-F106. [PMID: 18945826 DOI: 10.1152/ajprenal.90429.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Descending vasa recta (DVR) are 15-microm vessels that perfuse the renal medulla. Ouabain has been shown to augment DVR endothelial cytoplasmic Ca(2+) ([Ca(2+)](CYT)) signaling. In this study, we examined the expression of the ouabain-sensitive Na-K-ATPase alpha2 subunit in the rat renal vasculature and tested effects of acute ouabain exposure and chronic ouabain treatment on DVR. Immunostaining with antibodies directed against the alpha2 subunit verified its expression in both DVR pericytes and endothelium. Acute application of ouabain (100 or 500 nM) augmented the DVR nitric oxide generation stimulated by acetylcholine (ACh; 10 microM). At a concentration of 1 mM, ouabain constricted microperfused DVR, whereas at 100 nM, it was without effect. Acute ouabain (100 nM) did not augment constriction by angiotensin II (0.5 or 10 nM), whereas l-nitroarginine methyl ester-induced contraction of DVR was slightly enhanced. Ouabain-hypertensive (OH) rats were generated by chronic ouabain treatment (30 microg.kg(-1).day(-1), 5 wk). The acute endothelial [Ca(2+)](CYT) elevation by ouabain (100 nM) was absent in DVR endothelia of OH rats. The [Ca(2+)](CYT) response to 10 nM ACh was also eliminated, whereas the response to 10 microM ACh was not. The endothelial [Ca(2+)](CYT) response to bradykinin (100 nM) was significantly attenuated. We conclude that endothelial responses may offset the ability of acute ouabain exposure to enhance DVR vasoconstriction. Chronic exposure to ouabain, in vivo, leads to hypertension and DVR endothelial dysfunction, manifested as reduced [Ca(2+)](CYT) responses to both ouabain- and endothelium-dependent vasodilators.
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Affiliation(s)
- Chunhua Cao
- Department of Medicine, UMMS, Baltimore, MD 21201, USA
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Navar LG, Arendshorst WJ, Pallone TL, Inscho EW, Imig JD, Bell PD. The Renal Microcirculation. Microcirculation 2008. [DOI: 10.1016/b978-0-12-374530-9.00015-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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19
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Cao C, Lee-Kwon W, Payne K, Edwards A, Pallone TL. Descending vasa recta endothelia express inward rectifier potassium channels. Am J Physiol Renal Physiol 2007; 293:F1248-55. [PMID: 17670900 DOI: 10.1152/ajprenal.00278.2007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Descending vasa recta (DVR) are capillary-sized microvessels that supply blood flow to the renal medulla. They are composed of contractile pericytes and endothelial cells. In this study, we used the whole cell patch-clamp method to determine whether inward rectifier potassium channels (K(IR)) exist in the endothelia, affect membrane potential, and modulate intracellular Ca(2+) concentration ([Ca(2+)](cyt)). The endothelium was accessed for electrophysiology by removing abluminal pericytes from collagenase-digested vessels. K(IR) currents were recorded using symmetrical 140 mM K(+) solutions that served to maximize currents and eliminate cell-to-cell coupling by closing gap junctions. Large, inwardly rectifying currents were observed at membrane potentials below the equilibrium potential for K(+). Ba(2+) potently inhibited those currents in a voltage-dependent manner, with affinity k = 0.18, 0.33, 0.60, and 1.20 microM at -160, -120, -80, and -40 mV, respectively. Cs(+) also blocked those currents with k = 20, 48, 253, and 1,856 microM at -160, -120, -80, and -40 mV, respectively. In the presence of 1 mM ouabain, increasing extracellular K(+) concentration from 5 to 10 mM hyperpolarized endothelial membrane potential by 15 mV and raised endothelial [Ca(2+)](cyt). Both the K(+)-induced membrane hyperpolarization and the [Ca(2+)](cyt) elevation were reversed by Ba(2+). Immunochemical staining verified that both pericytes and endothelial cells of DVR express K(IR)2.1, K(IR)2.2, and K(IR)2.3 subunits. We conclude that strong, inwardly rectifying K(IR)2.x isoforms are expressed in DVR and mediate K(+)-induced hyperpolarization of the endothelium.
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Affiliation(s)
- Chunhua Cao
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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20
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Murata T, Lin MI, Stan RV, Bauer PM, Yu J, Sessa WC. Genetic evidence supporting caveolae microdomain regulation of calcium entry in endothelial cells. J Biol Chem 2007; 282:16631-43. [PMID: 17416589 DOI: 10.1074/jbc.m607948200] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Various cellular signals initiate calcium entry into cells, and there is evidence that lipid rafts and caveolae may concentrate proteins that regulate transmembrane calcium fluxes. Here, using mice deficient in caveolin-1 (Cav-1) and Cav-1 knock-out reconstituted with endothelium-specific Cav-1, we show that Cav-1 is essential for calcium entry in endothelial cells and governs the localization and protein-protein interactions between transient receptor channels C4 and C1. Thus, Cav-1 is required for calcium entry in vascular endothelial cells and perhaps other specialized cell types containing caveolae.
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Affiliation(s)
- Takahisa Murata
- Department of Pharmacology and Program in Vascular Cell Signaling and Therapeutics, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA
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Abstract
Endothelial cells, which form the inner cellular lining of blood vessels and lymphatics, display remarkable heterogeneity in structure and function. This is the second of a 2-part review on the phenotypic heterogeneity of blood vessel endothelial cells. The first part discusses the scope, the underlying mechanisms, and the diagnostic and therapeutic implications of phenotypic heterogeneity. Here, these principles are applied to an understanding of organ-specific phenotypes in representative vascular beds including arteries and veins, heart, lung, liver, and kidney. The goal is to underscore the importance of site-specific properties of the endothelium in mediating homeostasis and focal vascular pathology, while at the same time emphasizing the value of approaching the endothelium as an integrated system.
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Affiliation(s)
- William C Aird
- Division of Molecular and Vascular Medicine, Department of Medicine, and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass 02215, USA.
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22
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Lee-Kwon W, Goo JH, Zhang Z, Silldorff EP, Pallone TL. Vasa recta voltage-gated Na+ channel Nav1.3 is regulated by calmodulin. Am J Physiol Renal Physiol 2006; 292:F404-14. [PMID: 16912065 DOI: 10.1152/ajprenal.00070.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Rat descending vasa recta (DVR) express a tetrodotoxin (TTX)-sensitive voltage-operated Na(+) (Na(V)) conductance. We examined expression of Na(V) isoforms in DVR and tested for regulation of Na(V) currents by calmodulin (CaM). RT-PCR in isolated permeabilized DVR using degenerate primers targeted to TTX-sensitive isoforms amplified a product whose sequence identified only Na(V)1.3. Immunoblot of outer medullary homogenate verified Na(V)1.3 expression, and fluorescent immunochemistry showed Na(V)1.3 expression in isolated vessels. Immunochemistry in outer medullary serial sections confirmed that Na(V)1.3 is confined to alpha-smooth muscle actin-positive vascular bundles. Na(V)1.3 possesses a COOH-terminal CaM binding motifs. Using pull-down assays and immunoprecipitation experiments, we verified that CaM binds to either full-length Na(V)1.3 or a GST-Na(V)1.3 COOH-terminal fusion protein. In patch-clamp experiments, Na(V) currents were suppressed by calmodulin inhibitory peptide (CIP; 100 nM) or the CaM inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalene-sulphonamide hydrochloride (W7). Neither CIP nor W7 altered the voltage dependence of pericyte Na(V) currents; however, raising electrode free Ca(2+) from 20 to approximately 2,000 nM produced a depolarizing shift of activation. In vitro binding of CaM to GST-Na(V)1.3C was not affected by Ca(2+) concentration. We conclude that Na(V)1.3 is expressed by DVR, binds to CaM, and is regulated by CaM and Ca(2+). Inhibition of CaM binding suppresses pericyte Na(V) currents.
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Affiliation(s)
- Whaseon Lee-Kwon
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore 21201, USA
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Paquet M, Asay MJ, Fam SR, Inuzuka H, Castleberry AM, Oller H, Smith Y, Yun CC, Traynelis SF, Hall RA. The PDZ scaffold NHERF-2 interacts with mGluR5 and regulates receptor activity. J Biol Chem 2006; 281:29949-61. [PMID: 16891310 PMCID: PMC4670778 DOI: 10.1074/jbc.m602262200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The two members of the group I metabotropic glutamate receptor family, mGluR1 and mGluR5, both couple to G(q) to mediate rises in intracellular calcium. The alternatively spliced C termini (CT) of mGluRs1 and 5are known to be critical for regulating receptor activity and to terminate in motifs suggestive of potential interactions with PDZ domains. We therefore screened the CTs of both mGluR1a and mGluR5 against a PDZ domain proteomic array. Out of 96 PDZ domains examined, the domain that bound most strongly to mGluR5-CT was the second PDZ domain of the Na(+)/H(+) exchanger regulatory factor 2 (NHERF-2). This interaction was confirmed by reverse overlay, and a single point mutation to the mGluR5-CT was found to completely disrupt the interaction. Full-length mGluR5 robustly associated with full-length NHERF-2 in cells, as assessed by co-immunoprecipitation and confocal microscopy experiments. In contrast, mGluR1a was found to bind NHERF-2 in vitro with a weaker affinity than mGluR5, and furthermore mGluR1a did not detectably associate with NHERF-2 in a cellular context. Immunohistochemical experiments revealed that NHERF-2 and mGluR5 exhibit overlapping patterns of expression in mouse brain, being found most abundantly in astrocytic processes and postsynaptic neuronal elements. In functional experiments, the interaction of NHERF-2 with mGluR5 in cells was found to prolong mGluR5-mediated calcium mobilization and to also potentiate mGluR5-mediated cell death, whereas coexpression of mGluR1a with NHERF-2 had no evident effects on mGluR1a functional activity. These observations reveal that NHERF-2 can selectively modulate mGluR5 signaling, which may contribute to cell-specific regulation of mGluR5 activity.
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Affiliation(s)
- Maryse Paquet
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Matthew J. Asay
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Sami R. Fam
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Hiroyuki Inuzuka
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Amanda M. Castleberry
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Heide Oller
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Yoland Smith
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
- Yerkes National Primate Research Center, Emory University School of Medicine, Atlanta, Georgia 30322
| | - C. Chris Yun
- Division of Digestive Disease, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Stephen F. Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Randy A. Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
- To whom correspondence should be addressed: Dept. of Pharmacology, Emory University School of Medicine, 5113 Rollins Research Center, 1510 Clifton Rd., Atlanta, GA 30322. Tel.: 404-727-3699; Fax: 404-727-0365;
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Zhang Q, Cao C, Mangano M, Zhang Z, Silldorff EP, Lee-Kwon W, Payne K, Pallone TL. Descending vasa recta endothelium is an electrical syncytium. Am J Physiol Regul Integr Comp Physiol 2006; 291:R1688-99. [PMID: 16840652 DOI: 10.1152/ajpregu.00261.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined gap junction coupling of descending vasa recta (DVR). DVR endothelial cells or pericytes were depolarized to record the associated capacitance transients. Virtually all endothelia and some pericytes exhibited prolonged transients lasting 10-30 ms. Carbenoxolone (100 microM) and 18beta-glycyrrhetinic acid (18betaGRA; 100 microM) markedly shortened the endothelial transients. Carbenoxolone and heptanol (2 mM) reduced the pericyte capacitance transients when they were prolonged. Lucifer yellow (LY; 2 mM) was dialyzed into the cytoplasm of endothelial cells and pericytes. LY spread diffusely along the endothelial monolayer, whereas in most pericytes, it was confined to a single cell. In some pericytes, complex patterns of LY spreading were observed. DVR cells were depolarized by voltage clamp as fluorescence of bis(1,3-dibarbituric acid)-trimethine oxanol [DiBAC(4)(3)] was monitored approximately 200 microm away. A 40-mV endothelial depolarization was accompanied by a 26.1 +/- 5.5-mV change in DiBAC(4)(3) fluorescence. DiBAC(4)(3) fluorescence did not change after 18betaGRA or when pericytes were depolarized. Similarly, propagated cytoplasmic Ca(2+) responses arising from mechanical perturbation of the DVR wall were attenuated by 18betaGRA or heptanol. Connexin (Cx) immunostaining showed predominant linear Cx40 and Cx43 in endothelia, whereas Cx37 stained smooth muscle actin-positive pericytes. We conclude that the DVR endothelium is an electrical syncytium and that gap junction coupling in DVR pericytes exists but is less pronounced.
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Affiliation(s)
- Qingli Zhang
- Division of Nephrology N3W143, University of Maryland School of Medicine, 22 S. Greene Street, Baltimore, MD 21201, USA
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25
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Lombard JH. A novel mechanism for regulation of retinal blood flow by lactate: gap junctions, hypoxia, and pericytes. Am J Physiol Heart Circ Physiol 2006; 290:H921-2. [PMID: 16467461 DOI: 10.1152/ajpheart.01268.2005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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26
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PAQUET MARYSE, KUWAJIMA MASAAKI, YUN CCHRIS, SMITH YOLAND, HALL RANDYA. Astrocytic and neuronal localization of the scaffold protein Na+/H+ exchanger regulatory factor 2 (NHERF-2) in mouse brain. J Comp Neurol 2006; 494:752-62. [PMID: 16374813 PMCID: PMC1472808 DOI: 10.1002/cne.20854] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The Na+/H+ exchanger regulatory factor 2 (NHERF-2) is a scaffold protein that regulates cellular signaling by forming protein complexes. Several proteins known to interact with NHERF-2 are abundantly expressed in the central nervous system, but little is known about NHERF-2 localization in the brain. By using immunohistochemistry combined with light and electron microscopy, we found that many populations of astrocytes, as well as some populations of neurons, were immunopositive for NHERF-2 throughout the mouse brain. Quantitative analysis of the subcellular distribution of NHERF-2 immunostaining in four brain structures, cerebral cortex, hippocampus, striatum, and cerebellar cortex, showed that NHERF-2 was expressed mainly in astrocytic processes but was also sometimes observed in both pre- and postsynaptic neuronal elements. NHERF-2 immunostaining was associated mainly with the plasma membrane of neurons and astrocytes. However, NHERF-2 immunoreactivity was also observed in association with synaptic vesicles in putative glutamatergic axon terminals. The subcellular localization of NHERF-2 in brain is consistent with a role for NHERF-2 in forming complexes between cell surface and cytosolic proteins, and the preferential expression of NHERF-2 in astrocytes suggests that this scaffold protein may play an important role in astrocytic physiology.
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Affiliation(s)
- MARYSE PAQUET
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - MASAAKI KUWAJIMA
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
- Yerkes National Primate Research Center, Emory University School of Medicine, Atlanta, Georgia 30322
| | - C. CHRIS YUN
- Department of Medicine, Division of Digestive Disease, Emory University School of Medicine, Atlanta, Georgia 30322
| | - YOLAND SMITH
- Yerkes National Primate Research Center, Emory University School of Medicine, Atlanta, Georgia 30322
- Department of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - RANDY A. HALL
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
- *Correspondence to: Randy A. Hall, Department of Pharmacology, Emory University School of Medicine, 5113 Rollins Research Center, 1510 Clifton Rd., Atlanta, GA 30322. E-mail:
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27
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Owsianik G, D'hoedt D, Voets T, Nilius B. Structure–function relationship of the TRP channel superfamily. Rev Physiol Biochem Pharmacol 2006. [DOI: 10.1007/s10254-005-0006-0] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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28
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Goel M, Sinkins WG, Zuo CD, Estacion M, Schilling WP. Identification and localization of TRPC channels in the rat kidney. Am J Physiol Renal Physiol 2005; 290:F1241-52. [PMID: 16303855 DOI: 10.1152/ajprenal.00376.2005] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
It is well established that transient receptor potential (TRP) channels are activated following stimulation of G protein-coupled membrane receptors linked to PLC, but their differential expression in various cells of the renal nephron has not been described. In the present study, immunoprecipitations from rat kidney lysates followed by Western blot analysis using TRPC-specific, affinity-purified antibodies revealed the presence of TRPC1, -C3, and -C6. TRPC4, -C5, and -C7 were nondetectable. TRPC1 immunofluorescence was detected in glomeruli and specific tubular cells of the cortex and outer medulla. TRPC1 colocalized with aquaporin-1, a marker for proximal tubule and thin descending limb, but not with aquaporin-2, a marker for connecting tubule and collecting duct cells. TRPC3 and -C6 immunolabeling was predominantly confined to glomeruli and specific tubular cells of the cortex and both the outer and inner medulla. TRPC3 and -C6 colocalized with aquaporin-2, but not with the Na(+)/Ca(2+) exchanger or peanut lectin. Thus TRPC3 and -C6 proteins are expressed in principle cells of the collecting duct. In polarized cultures of M1 and IMCD-3 collecting duct cells, TRPC3 was localized exclusively to the apical domain, whereas TRPC6 was found in both the basolateral and apical membranes. TRPC3 and TRPC6 were also detected in primary podocyte cultures, whereas TRPC1 was exclusively expressed in mesangial cell cultures. Specific immunopositive labeling for TRPC4, -C5, or -C7 was not observed in kidney sections or cell lines. These results suggest that TRPC1, -C3, and -C6 may play a functional role in PLC-dependent signaling in specific regions of the nephron.
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Affiliation(s)
- Monu Goel
- Rammelkamp Ctr. for Education and Research, Rm. R-322, MetroHealth Medical Ctr., 2500 MetroHealth Dr., Cleveland, OH 44109-1998, USA
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Kanjhan R, Hryciw DH, Yun CC, Bellingham MC, Poronnik P. Postnatal developmental expression of the PDZ scaffolds Na+ -H+ exchanger regulatory factors 1 and 2 in the rat cochlea. Cell Tissue Res 2005; 323:53-70. [PMID: 16160858 PMCID: PMC1472810 DOI: 10.1007/s00441-005-0051-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2005] [Accepted: 06/28/2005] [Indexed: 01/07/2023]
Abstract
Sensory transduction in the mammalian cochlea requires the maintenance of specialized fluid compartments with distinct ionic compositions. This is achieved by the concerted action of diverse ion channels and transporters, some of which can interact with the PDZ scaffolds, Na(+)-H(+) exchanger regulatory factors 1 and 2 (NHERF-1, NHERF-2). Here, we report that NHERF-1 and NHERF-2 are widely expressed in the rat cochlea, and that their expression is developmentally regulated. Reverse transcription/polymerase chain reaction (RT-PCR) and Western blotting initially confirmed the RNA and protein expression of NHERFs. We then performed immunohistochemistry on cochlea during various stages of postnatal development. Prior to the onset of hearing (P8), NHERF-1 immunolabeling was prominently polarized to the apical membrane of cells lining the endolymphatic compartment, including the stereocilia and cuticular plates of the inner and outer hair cells, marginal cells of the stria vascularis, Reissner's epithelia, and tectorial membrane. With maturation (P21, P70), NHERF-1 immunolabeling was reduced in the above structures, whereas labeling increased in the apical membrane of the interdental cells of the spiral limbus and the inner and outer sulcus cells, Hensen's cells, the inner and outer pillar cells, Deiters cells, the inner border cells, spiral ligament fibrocytes, and spiral ganglion neurons (particularly type II). NHERF-1 expression in strial basal and intermediate cells was persistent. NHERF-2 immunolabeling was similar to that for NHERF-1 during postnatal development, with the exception of expression in the synaptic regions beneath the outer hair cells. NHERF-1 and NHERF-2 co-localized with glial fibrillary acidic protein and vimentin in glia. The cochlear localization of NHERF scaffolds suggests that they play important roles in the developmental regulation of ion transport, homeostasis, and auditory neurotransmission.
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Affiliation(s)
- Refik Kanjhan
- School of Biomedical Sciences, The University of Queensland, St Lucia, 4072, Queensland, Australia.
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30
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Cao C, Lee-Kwon W, Silldorff EP, Pallone TL. KATP channel conductance of descending vasa recta pericytes. Am J Physiol Renal Physiol 2005; 289:F1235-45. [PMID: 16048905 DOI: 10.1152/ajprenal.00111.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using nystatin-perforated patch-clamp and whole cell recording, we tested the hypothesis that K(ATP) channels contribute to resting conductance of rat descending vasa recta (DVR) pericytes and are modulated by vasoconstrictors. The K(ATP) blocker glybenclamide (Glb; 10 microM) depolarized pericytes and inhibited outward currents of cells held at -40 mV. K(ATP) openers pinacidil (Pnc; 10 microM) and P-1075 (1 microM) hyperpolarized pericytes and transiently augmented outward currents. All effects of Pnc and P-1075 were fully reversed by Glb. Inward currents of pericytes held at -60 mV in symmetrical 140 mM K(+) were markedly augmented by Pnc and fully reversed by Glb. Ramp depolarizations in symmetrical K(+), performed in Pnc and Pnc + Glb, yielded a Pnc-induced, Glb-sensitive K(ATP) difference current that lacked rectification and reversed at 0 mV. Immunostaining identified both K(IR)6.1, K(IR)6.2 inward rectifier subunits and sulfonurea receptor subtype 2B. ANG II (1 and 10 nM) and endothelin-1 (10 nM) but not vasopressin (100 nM) significantly lowered holding current at -40 mV and abolished Pnc-stimulated outward currents. We conclude that DVR pericytes express K(ATP) channels that make a significant contribution to basal K(+) conductance and are inhibited by ANG II and endothelin-1.
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Affiliation(s)
- Chunhua Cao
- Division of Nephrology, Department of Medicine, University of Maryland, Baltimore, 21201, USA
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31
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Schaefer M. Homo- and heteromeric assembly of TRP channel subunits. Pflugers Arch 2005; 451:35-42. [PMID: 15971080 DOI: 10.1007/s00424-005-1467-6] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2005] [Accepted: 05/07/2005] [Indexed: 12/29/2022]
Abstract
Mammalian homologues of the Drosophila melanogaster transient receptor potential (TRP) channels are the second largest cation channel family within the superfamily of hexahelical cation channels. Most mammalian TRP channels function as homooligomers and mediate mono- or divalent cation entry upon activation by a variety of stimuli. Because native TRP channels may be multimeric proteins of possibly complex composition, it is difficult to compare cation conductances in native tissues to those of clearly defined homomeric TRP channel complexes in living cells. Therefore, the possibility of heteromeric TRP channel assembly has been investigated in recent years by several groups. As a major conclusion of these studies, most heteromeric TRP channel complexes appear to consist of subunit combinations only within relatively narrow confines of phylogenetic subfamilies. Although the general capability of heteromer formation between closely related TRP channel subunits is now clearly established, we are only beginning to understand whether these heteromeric complexes are of physiological significance. This review summarizes the current knowledge on the promiscuity and specificity of the assembly of channel complexes composed of TRPC-, TRPV- and TRPM-subunits of mammalian TRP channels.
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Affiliation(s)
- Michael Schaefer
- Institut für Pharmakologie, Charité, Universitätsmedizin Berlin, Campus Benjamin Franklin, Thielallee 67-73, 14195 Berlin, Germany.
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