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Navarro-Pérez M, Estadella I, Benavente-Garcia A, Orellana-Fernández R, Petit A, Ferreres JC, Felipe A. The Phosphorylation of Kv1.3: A Modulatory Mechanism for a Multifunctional Ion Channel. Cancers (Basel) 2023; 15:2716. [PMID: 37345053 DOI: 10.3390/cancers15102716] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/04/2023] [Accepted: 05/09/2023] [Indexed: 06/23/2023] Open
Abstract
The voltage-gated potassium channel Kv1.3 plays a pivotal role in a myriad of biological processes, including cell proliferation, differentiation, and apoptosis. Kv1.3 undergoes fine-tuned regulation, and its altered expression or function correlates with tumorigenesis and cancer progression. Moreover, posttranslational modifications (PTMs), such as phosphorylation, have evolved as rapid switch-like moieties that tightly modulate channel activity. In addition, kinases are promising targets in anticancer therapies. The diverse serine/threonine and tyrosine kinases function on Kv1.3 and the effects of its phosphorylation vary depending on multiple factors. For instance, Kv1.3 regulatory subunits (KCNE4 and Kvβ) can be phosphorylated, increasing the complexity of channel modulation. Scaffold proteins allow the Kv1.3 channelosome and kinase to form protein complexes, thereby favoring the attachment of phosphate groups. This review compiles the network triggers and signaling pathways that culminate in Kv1.3 phosphorylation. Alterations to Kv1.3 expression and its phosphorylation are detailed, emphasizing the importance of this channel as an anticancer target. Overall, further research on Kv1.3 kinase-dependent effects should be addressed to develop effective antineoplastic drugs while minimizing side effects. This promising field encourages basic cancer research while inspiring new therapy development.
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Affiliation(s)
- María Navarro-Pérez
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | - Irene Estadella
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | - Anna Benavente-Garcia
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | | | - Anna Petit
- Departament de Patologia, Hospital Universitari de Bellvitge, IDIBELL, L'Hospitalet del Llobregat, 08908 Barcelona, Spain
| | - Joan Carles Ferreres
- Servei d'Anatomia Patològica, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT-CERCA), 08208 Sabadell, Spain
- Departament de Ciències Morfològiques, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
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Liu H, Liu J, Xu E, Tu G, Guo M, Liang S, Xiong H. Human immunodeficiency virus protein Tat induces oligodendrocyte injury by enhancing outward K + current conducted by K V1.3. Neurobiol Dis 2016; 97:1-10. [PMID: 27816768 DOI: 10.1016/j.nbd.2016.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/21/2016] [Accepted: 10/30/2016] [Indexed: 12/28/2022] Open
Abstract
Brain white matter damage is frequently detected in patients infected with human immunodeficiency virus type 1 (HIV-1). White matter is composed of neuronal axons sheathed by oligodendrocytes (Ols), the myelin-forming cells in central nervous system. Ols are susceptible to HIV-1 viral trans-activator of transcription (Tat) and injury of Ols results in myelin sheath damage. It has been demonstrated that activation of voltage-gated K+ (KV) channels induces cell apoptosis and Ols predominantly express K+ channel KV1.3. It is our hypothesis that Tat injures Ols via activation of KV1.3. To test this hypothesis, we studied the involvement of KV1.3 in Tat-induced Ol/myelin injury both in vitro and ex vivo. Application of Tat to primary rat Ol cultures enhanced whole-cell KV1.3 current recorded under voltage clamp configuration and confirmed by specific KV1.3 antagonists Margatoxin (MgTx) and 5-(4-phenoxybutoxy) psoralen (PAP). The Tat enhancement of KV1.3 current was associated with Tat-induced Ol apoptosis, which was blocked by MgTx and PAP or by siRNA knockdown of KV1.3 gene. The Tat-induced Ol injury was validated in cultured rat brain slices, particularly in corpus callosum and striatum, that incubation of the slices with Tat resulted in myelin damage and reduction of myelin basic protein which were also blocked by aforementioned KV1.3 antagonists. Further studies revealed that Tat interacts with KV1.3 as determined by protein pull-down of recombinant GST-Tat with KV1.3 expressed in rat brains and HEK293 cells. Such protein-protein interaction may alter channel protein phosphorylation, resultant channel activity and consequent Ol/myelin injury. Taken together, these results demonstrate an involvement of KV1.3 in Tat- induced Ol/myelin injury, a potential mechanism for the pathogenesis of HIV-1-associated white matter damage.
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Affiliation(s)
- Han Liu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Jianuo Liu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Enquan Xu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Guihua Tu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Minglei Guo
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Shangdong Liang
- Department of Physiology, College of Basic Medical Sciences, Nanchang University, Nanchang, Jiangxi, People's Republic of China
| | - Huangui Xiong
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA.
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Bae SH, Kim DH, Shin SK, Choi JS, Park KS. Src regulates membrane trafficking of the Kv3.1b channel. FEBS Lett 2013; 588:86-91. [PMID: 24291260 DOI: 10.1016/j.febslet.2013.11.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/01/2013] [Accepted: 11/05/2013] [Indexed: 10/26/2022]
Abstract
The Kv3.1 channel plays a crucial role in regulating the high-frequency firing properties of neurons. Here, we determined whether Src regulates the subcellular distributions of the Kv3.1b channel. Co-expression of active Src induced a dramatic redistribution of Kv3.1b to the endoplasmic reticulum. Furthermore, co-expression of the Kv3.1b channel with active Src induced a remarkable decrease in the pool of Kv3.1b at the cell surface. Moreover, the co-expression of active Src results in a significant decrease in the peak current densities of the Kv3.1b channel, and a substantial alteration in the voltage dependence of its steady-state inactivation. Taken together, these results indicate that Src kinase may play an important role in regulating membrane trafficking of Kv3.1b channels.
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Affiliation(s)
- Seong Han Bae
- Department of Physiology, Kyung Hee University School of Medicine, Seoul 130-701, South Korea
| | - Dong Hyun Kim
- College of Pharmacy, Catholic University of Korea, Bucheon 420-743, Gyeonggi-Do, South Korea
| | - Seok Kyo Shin
- Department of Physiology, Kyung Hee University School of Medicine, Seoul 130-701, South Korea
| | - Jin Sung Choi
- College of Pharmacy, Catholic University of Korea, Bucheon 420-743, Gyeonggi-Do, South Korea
| | - Kang-Sik Park
- Department of Physiology, Kyung Hee University School of Medicine, Seoul 130-701, South Korea; Biomedical Science Institute, Kyung Hee University School of Medicine, Seoul 130-701, South Korea.
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Tucker KR, Godbey SJ, Thiebaud N, Fadool DA. Olfactory ability and object memory in three mouse models of varying body weight, metabolic hormones, and adiposity. Physiol Behav 2012; 107:424-32. [PMID: 22995978 PMCID: PMC3513555 DOI: 10.1016/j.physbeh.2012.09.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/18/2012] [Accepted: 09/11/2012] [Indexed: 01/15/2023]
Abstract
Physiological and nutritional state can modify sensory ability and perception through hormone signaling. Obesity and related metabolic disorders present a chronic imbalance in hormonal signaling that could impact sensory systems. In the olfactory system, external chemical cues are transduced into electrical signals to encode information. It is becoming evident that this system can also detect internal chemical cues in the form of molecules of energy homeostasis and endocrine hormones, whereby neurons of the olfactory system are modulated to change animal behavior towards olfactory cues. We hypothesized that chronic imbalance in hormonal signaling and energy homeostasis due to obesity would thereby disrupt olfactory behaviors in mice. To test this idea, we utilized three mouse models of varying body weight, metabolic hormones, and visceral adiposity - 1) C57BL6/J mice maintained on a condensed-milk based, moderately high-fat diet (MHF) of 32% fat for 6 months as the diet-induced obesity model, 2) an obesity-resistant, lean line of mice due to a gene-targeted deletion of a voltage-dependent potassium channel (Kv 1.3-null), and 3) a genetic model of obesity as a result of a gene-targeted deletion of the melanocortin 4 receptor (MC4R-null). Diet-induced obese (DIO) mice failed to find a fatty-scented hidden peanut butter cracker, based solely on olfactory cues, any faster than an unscented hidden marble, initially suggesting general anosmia. However, when these DIO mice were challenged to find a sweet-scented hidden chocolate candy, they had no difficulty. Furthermore, DIO mice were able to discriminate between fatty acids that differ by a single double bond and are components of the MHF diet (linoleic and oleic acid) in a habituation-dishabituation paradigm. Obesity-resistant, Kv1.3-null mice exhibited no change in scented object retrieval when placed on the MHF-diet, nor did they perform differently than wild-type mice in parallel habituation-dishabituation paradigms of fatty food-related odor components. Genetically obese, MC4R-null mice successfully found hidden scented objects, but did so more slowly than lean, wild-type mice, in an object-dependent fashion. In habituation-dishabituation trials of general odorants, MC4R-null mice failed to discriminate a novel odor, but were able to distinguish two fatty acids. Object memory recognition tests for short- and long-term memory retention demonstrated that maintenance on the MHF diet did not modify the ability to perform these tasks independent of whether mice became obese or were resistant to weight gain (Kv1.3-null), however, the genetically predisposed obese mice (MC4R-null) failed the long-term object memory recognition performed at 24h. These results demonstrate that even though both the DIO mice and genetically predisposed obese mice are obese, they vary in the degree to which they exhibit behavioral deficits in odor detection, odor discrimination, and long-term memory.
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Affiliation(s)
- Kristal R Tucker
- Department of Biological Science, 319 Stadium Drive, Suite 3008, King Life Sciences Building, The Florida State University, Tallahassee, FL 32306-4295, United States; Program in Neuroscience, 319 Stadium Drive, Suite 3008, King Life Sciences Building, The Florida State University, Tallahassee, FL 32306-4295, United States.
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5
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Kuras Z, Kucher V, Gordon SM, Neumeier L, Chimote AA, Filipovich AH, Conforti L. Modulation of Kv1.3 channels by protein kinase A I in T lymphocytes is mediated by the disc large 1-tyrosine kinase Lck complex. Am J Physiol Cell Physiol 2012; 302:C1504-12. [PMID: 22378744 DOI: 10.1152/ajpcell.00263.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The cAMP/PKA signaling system constitutes an inhibitory pathway in T cells and, although its biochemistry has been thoroughly investigated, its possible effects on ion channels are still not fully understood. K(V)1.3 channels play an important role in T-cell activation, and their inhibition suppresses T-cell function. It has been reported that PKA modulates K(V)1.3 activity. Two PKA isoforms are expressed in human T cells: PKAI and PKAII. PKAI has been shown to inhibit T-cell activation via suppression of the tyrosine kinase Lck. The aim of this study was to determine the PKA isoform modulating K(V)1.3 and the signaling pathway underneath. 8-Bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP), a nonselective activator of PKA, inhibited K(V)1.3 currents both in primary human T and in Jurkat cells. This inhibition was prevented by the PKA blocker PKI(6-22). Selective knockdown of PKAI, but not PKAII, with siRNAs abolished the response to 8-BrcAMP. Additional studies were performed to determine the signaling pathway mediating PKAI effect on K(V)1.3. Overexpression of a constitutively active mutant of Lck reduced the response of K(V)1.3 to 8-Br-cAMP. Moreover, knockdown of the scaffolding protein disc large 1 (Dlg1), which binds K(V)1.3 to Lck, abolished PKA modulation of K(V)1.3 channels. Immunohistochemistry studies showed that PKAI, but not PKAII, colocalizes with K(V)1.3 and Dlg1 indicating a close proximity between these proteins. These results indicate that PKAI selectively regulates K(V)1.3 channels in human T lymphocytes. This effect is mediated by Lck and Dlg1. We thus propose that the K(V)1.3/Dlg1/Lck complex is part of the membrane pathway that cAMP utilizes to regulate T-cell function.
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Affiliation(s)
- Zerrin Kuras
- Department of Internal Medicine, 231 Albert Sabin Way, University of Cincinnati, Cincinnati, OH 45267-0585, USA
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6
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Martin GV, Yun Y, Conforti L. Modulation of T cell activation by localized K⁺ accumulation at the immunological synapse--a mathematical model. J Theor Biol 2012; 300:173-82. [PMID: 22285786 DOI: 10.1016/j.jtbi.2012.01.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 12/21/2011] [Accepted: 01/11/2012] [Indexed: 01/06/2023]
Abstract
The response of T cells to antigens (T cell activation) is marked by an increase in intracellular Ca²⁺ levels. Voltage-gated and Ca²⁺-dependent K⁺ channels control the membrane potential of human T cells and regulate Ca²⁺ influx. This regulation is dependent on proper accumulation of K⁺ channels at the immunological synapse (IS) a signaling zone that forms between a T cell and antigen presenting cell. It is believed that the IS provides a site for regulation of the activation response and that K⁺ channel inhibition occurs at the IS, but the underlying mechanisms are unknown. A mathematical model was developed to test whether K⁺ efflux through K⁺ channels leads to an accumulation of K⁺ in the IS cleft, ultimately reducing K⁺ channel function and intracellular Ca²⁺ concentration ([Ca²⁺](i)). Simulations were conducted in models of resting and activated T cell subsets, which express different levels of K⁺ channels, by varying the K⁺ diffusion constant and the spatial localization of K⁺ channels at the IS. K⁺ accumulation in the IS cleft was calculated to increase K⁺ concentration ([K⁺]) from its normal value of 5.0 mM to 5.2-10.0 mM. Including K⁺ accumulation in the model of the IS reduced calculated K⁺ current by 1-12% and consequently, reduced calculated [Ca²⁺](i) by 1-28%. Significant reductions in K⁺ current and [Ca²⁺](i) only occurred in activated T cell simulations when most K⁺ channels were centrally clustered at the IS. The results presented show that the localization of K⁺ channels at the IS can produce a rise in [K⁺] in the IS cleft and lead to a substantial decrease in K⁺ currents and [Ca²⁺](i) in activated T cells thus providing a feedback inhibitory mechanism during T cell activation.
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Affiliation(s)
- Geoffrey V Martin
- Department of Internal Medicine, 231 A. Sabin Way, Division of Nephrology, University of Cincinnati, Cincinnati, OH 45267-0585, USA
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7
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Nicolaou SA, Neumeier L, Steckly A, Kucher V, Takimoto K, Conforti L. Localization of Kv1.3 channels in the immunological synapse modulates the calcium response to antigen stimulation in T lymphocytes. THE JOURNAL OF IMMUNOLOGY 2009; 183:6296-302. [PMID: 19841189 DOI: 10.4049/jimmunol.0900613] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The immunological synapse (IS), a highly organized structure that forms at the point of contact between a T cell and an APC, is essential for the proper development of signaling events, including the Ca(2+) response. Kv1.3 channels control Ca(2+) homeostasis in human T cells and move into the IS upon Ag presentation. However, the process involved in channel accumulation in the IS and the functional implications of this localization are not yet known. Here we define the movement of Kv1.3 into the IS and study whether Kv1.3 localization into the IS influences Ca(2+) signaling in Jurkat T cells. Crosslinking of the channel protein with an extracellular Ab limits Kv1.3 mobility and accumulation at the IS. Moreover, Kv1.3 recruitment to the IS does not involve the transport of newly synthesized channels and it does not occur through recycling of membrane channels. Kv1.3 localization in the IS modulates the Ca(2+) response. Blockade of Kv1.3 movement into the IS by crosslinking significantly increases the amplitude of the Ca(2+) response triggered by anti-CD3/anti-CD28-coated beads, which induce the formation of the IS. On the contrary, the Ca(2+) response induced by TCR stimulation without the formation of the IS with soluble anti-CD3/anti-CD28 Abs is unaltered. The results presented herein indicate that, upon Ag presentation, membrane-incorporated Kv1.3 channels move along the plasma membrane to localize in the IS. This localization is important to control the amplitude of the Ca(2+) response, and disruption of this process can account for alterations of downstream Ca(2+)-dependent signaling events.
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Affiliation(s)
- Stella A Nicolaou
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
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8
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Abstract
For more than 25 years, it has been widely appreciated that Ca2+ influx is essential to trigger T-lymphocyte activation. Patch clamp analysis, molecular identification, and functional studies using blockers and genetic manipulation have shown that a unique contingent of ion channels orchestrates the initiation, intensity, and duration of the Ca2+ signal. Five distinct types of ion channels--Kv1.3, KCa3.1, Orai1+ stromal interacting molecule 1 (STIM1) [Ca2+-release activating Ca2+ (CRAC) channel], TRPM7, and Cl(swell)--comprise a network that performs functions vital for ongoing cellular homeostasis and for T-cell activation, offering potential targets for immunomodulation. Most recently, the roles of STIM1 and Orai1 have been revealed in triggering and forming the CRAC channel following T-cell receptor engagement. Kv1.3, KCa3.1, STIM1, and Orai1 have been found to cluster at the immunological synapse following contact with an antigen-presenting cell; we discuss how channels at the synapse might function to modulate local signaling. Immuno-imaging approaches are beginning to shed light on ion channel function in vivo. Importantly, the expression pattern of Ca2+ and K+ channels and hence the functional network can adapt depending upon the state of differentiation and activation, and this allows for different stages of an immune response to be targeted specifically.
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Affiliation(s)
- Michael D Cahalan
- Department of Physiology and Biophysics, and the Institute for Immunology, University of California, Irvine, Irvine, CA 92697-4561, USA.
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9
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Szigligeti P, Neumeier L, Duke E, Chougnet C, Takimoto K, Lee SM, Filipovich AH, Conforti L. Signalling during hypoxia in human T lymphocytes--critical role of the src protein tyrosine kinase p56Lck in the O2 sensitivity of Kv1.3 channels. J Physiol 2006; 573:357-70. [PMID: 16600997 PMCID: PMC1779731 DOI: 10.1113/jphysiol.2006.109967] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
T lymphocytes encounter hypoxia when they migrate to pathological sites such as tumours and wounds. The inability of T cells to provide an efficient defence at these sites can in part be explained by the hypoxic environment. Kv 1.3 channels, important components of the T cell activation process are inhibited by hypoxia and their inhibition accounts for a hypoxia-induced decrease in T cell proliferation. Although Kv 1.3 channels play a key role in T cell O(2) sensing, the signalling mechanisms mediating their response to hypoxia are still not understood. In this study, we show that the src-protein tyrosine kinase p56Lck (Lck) is required for Kv 1.3 channel response to hypoxia. Pre-exposure to the src inhibitor PP2 abolished the hypoxia-induced inhibition of Kv 1.3 channels in primary human T lymphocytes. Moreover, Kv 1.3 channel sensitivity to hypoxia was lost in Lck-deficient Jurkat T cells. Further studies with recombinant Kv 1.3 channels showed that Kv 1.3 channels lack intrinsic O(2) sensitivity, but delivery of Lck into the cells and transfection of a constitutively active Lck (Y505FLck) restored their sensitivity to hypoxia. Although Lck is necessary for the Kv 1.3 channel response to hypoxia, it does not directly inhibit Kv 1.3 channels. Indeed, under normal oxygen tension, delivery of active Lck into L929 cells and overexpression of Y505FLck did not decrease recombinant Kv 1.3 currents. On the contrary, activation of endogenous src kinases increased wild-type Kv 1.3 currents in T lymphocytes. Our findings indicate that Lck is required for the acute response to hypoxia of human T lymphocytes as it is necessary to confer O(2) sensitivity on Kv 1.3 channels.
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Affiliation(s)
- Peter Szigligeti
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267-0585, USA
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10
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Abstract
SRC family kinases are a group of nine cytoplasmic protein tyrosine kinases essential for many cell functions. Some appear to be ubiquitously expressed, whereas others are highly tissue specific. The ability of members of the SRC family to influence ion transport has been recognized for several years. Mounting evidence suggests a broad role for SRC family kinases in the cell response to both hypertonic and hypotonic stress, and in the ensuing regulatory volume increase or decrease. In addition, members of this tyrosine kinase family participate in the mechanotransduction that accompanies cell membrane deformation. Finally, at least one SRC family member operates in concert with the p38 MAPK to regulate tonicity-dependent gene transcription.
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Affiliation(s)
- David M Cohen
- Division of Nephrology, Mailcode PP262, Oregon Health and Science Univ. 3314 SW US Veterans Hospital Rd., Portland, OR 97239, USA.
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Richman RW, Tombler E, Lau KK, Anantharam A, Rodriguez J, O'Bryan JP, Diversé-Pierluissi MA. N-type Ca2+ Channels as Scaffold Proteins in the Assembly of Signaling Molecules for GABAB Receptor Effects. J Biol Chem 2004; 279:24649-58. [PMID: 15047708 DOI: 10.1074/jbc.m312182200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An emerging concept in signal transduction is the organization of neuronal receptors and channels into microdomains in which signaling proteins are brought together to regulate functional responses. With the multiplicity of potential protein-protein interactions arises the need for the regulation and timing of these interactions. We have identified N-type Ca(2+) channel-signaling molecule complexes formed at different times upon activation of gamma-aminobutyric acid, type B, receptors. The first type of interaction involves pre-association of signaling proteins such as Src kinase with the Ca(2+) channel, because it is rapidly activated by the receptors and regulates the magnitude of the inhibition of the Ca(2+) channel. The second type of interaction involves signaling molecules that are recruited to the channel by receptor activation and control the rate of the channel response. Recruitment of members of the Ras pathway has two effects as follows: 1) modulation of the rate of onset of the gamma-aminobutyric acid-mediated inhibition of Ca(2+) current, and 2) activation of MAP kinase. Our results suggest that the Ca(2+) channel alpha(1) subunit functions as a dynamic scaffold allowing assembly of intracellular signaling components that alter channel activity and route signals to the MAP kinase pathway.
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Affiliation(s)
- Ryan W Richman
- Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, New York 10029, USA
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Uzdensky A, Kolosov M, Bragin D, Dergacheva O, Vanzha O, Oparina L. Involvement of adenylate cyclase and tyrosine kinase signaling pathways in response of crayfish stretch receptor neuron and satellite glia cell to photodynamic treatment. Glia 2004; 49:339-48. [PMID: 15494984 DOI: 10.1002/glia.20122] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neuroglial interactions are most profound during development or damage of nerve tissue. We studied the responses of crayfish stretch receptor neurons (SRN) and satellite glial cells to photosensitization with sulfonated aluminum phthalocyanine Photosens. Although Photosens was localized mainly in the glial envelope, neurons were very sensitive to photodynamic treatment. Photosensitization gradually inhibited and then abolished neuron activity. Neuronal and glial nuclei shrank. Some neurons and glial cells lost the integrity of the plasma membrane and died through necrosis after the treatment. The nuclei of other glial cells but not neurons become fragmented, indicating apoptosis. The number of glial nuclei around neuron soma increased, probably indicating proliferation for enhanced neuron protection. Adenylate cyclase (AC) inhibition by MDL-12330A, or tyrosine kinase (TK) inhibition by genistein, shortened neuron lifetime, whereas AC activation by forskolin or protein tyrosine phosphatases (PTP) inhibition by sodium orthovanadate prolonged neuronal activity. Therefore, cAMP and phosphotyrosines produced by AC and TK, respectively, protected SRN against photoinactivation. AC inhibition reduced photodamage of the plasma membrane and subsequent necrosis in neuronal and glial cells. AC activation prevented apoptosis in photosensitized glial cells and stimulated glial proliferation. TK inhibition protected neurons but not glia against photoinduced membrane permeabilization and subsequent necrosis whereas PTP inhibition more strongly protected glial cells. Therefore, both signaling pathways involving cAMP and phosphotyrosines might contribute to the maintenance of neuronal activity and the integrity of the neuronal and glial plasma membranes. Adenylate cyclase but not phosphotyrosine signaling pathways modulated glial apoptosis and proliferation under photooxidative stress.
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Affiliation(s)
- Anatoly Uzdensky
- Department of Biophysics and Biocybernetics, Rostov State University, 194/1 Stachky ave., Institute of Neurocybernetics, Rostov-on-Don 344090, Russia.
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13
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Modulation of Kv1.5 currents by Src tyrosine phosphorylation: potential role in the differentiation of astrocytes. J Neurosci 2000. [PMID: 10884308 DOI: 10.1523/jneurosci.20-14-05245.2000] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Using biophysical techniques, we previously have implicated outwardly rectifying potassium currents in the proliferation of cultured spinal cord astrocytes and have demonstrated that delayed rectifier potassium currents (I(Kd)), in particular, are upregulated on entry into the cell cycle and downregulated with cell cycle exit and differentiation. In the present study, using specific antibodies and antisense oligodeoxynucleotides, we show that this proliferation-dependent potassium current is mediated by the Shaker potassium channel Kv1.5. Downregulation of Kv1.5 protein by antisense oligodeoxynucleotides reduces astrocyte proliferation by approximately 50%, although no observed changes occur in Kv1.5 protein expression during spontaneous differentiation in culture. Tyrosine phosphorylation of Kv1.5, however, is downregulated markedly in differentiated cells but unaltered on cell cycle arrest. Using immunoprecipitation, we show that Kv1.5 is associated with Src family protein tyrosine kinases and that this association does not change with cell differentiation. Inhibition of kinase activity with the Src-specific inhibitor PP2 decreases Kv1.5 phosphorylation, reduces I(Kd), and inhibits astrocyte proliferation, specifically in the G(0)/G(1) phase of cell cycle. Conversely, I(Kd) are potentiated when active Src is present in the pipette. Transfection of quiescent astrocytes with constitutively active Src (Src Y529F) causes marked upregulation of astrocyte proliferation. These data suggest that Kv1. 5 is phosphorylated constitutively by Src kinases during growth and that downregulation of Src activity may underlie both astrocyte differentiation and the accompanying changes in delayed rectifier potassium channel activity.
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