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Hamar J, Cnaani A, Kültz D. Transcriptional upregulation of the myo-inositol biosynthesis pathway is enhanced by NFAT5 in hyperosmotically stressed tilapia cells. Am J Physiol Cell Physiol 2024; 327:C545-C556. [PMID: 38946247 DOI: 10.1152/ajpcell.00187.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 06/13/2024] [Accepted: 06/16/2024] [Indexed: 07/02/2024]
Abstract
Euryhaline fish experience variable osmotic environments requiring physiological adjustments to tolerate elevated salinity. Mozambique tilapia (Oreochromis mossambicus) possess one of the highest salinity tolerance limits of any fish. In tilapia and other euryhaline fish species, the myo-inositol biosynthesis (MIB) pathway enzymes, myo-inositol phosphate synthase (MIPS) and inositol monophosphatase 1 (IMPA1.1), are among the most upregulated mRNAs and proteins indicating the high importance of this pathway for hyperosmotic (HO) stress tolerance. These abundance changes must be precluded by HO perception and signaling mechanism activation to regulate the expression of MIPS and IMPA1.1 genes. In previous work using a O. mossambicus cell line (OmB), a reoccurring osmosensitive enhancer element (OSRE1) in both MIPS and IMPA1.1 was shown to transcriptionally upregulate these enzymes in response to HO stress. The OSRE1 core consensus (5'-GGAAA-3') matches the core binding sequence of the predominant mammalian HO response transcription factor, nuclear factor of activated T-cells (NFAT5). HO-challenged OmB cells showed an increase in NFAT5 mRNA suggesting NFAT5 may contribute to MIB pathway regulation in euryhaline fish. Ectopic expression of wild-type NFAT5 induced an IMPA1.1 promoter-driven reporter by 5.1-fold (P < 0.01). Moreover, expression of dominant negative NFAT5 in HO media resulted in a 47% suppression of the reporter signal (P < 0.005). Furthermore, reductions of IMPA1.1 (37-49%) and MIPS (6-37%) mRNA abundance were observed in HO-challenged NFAT5 knockout cells relative to control cells. Collectively, these multiple lines of experimental evidence establish NFAT5 as a tilapia transcription factor contributing to HO-induced activation of the MIB pathway.NEW & NOTEWORTHY In our study, we use a multi-pronged synthetic biology approach to demonstrate that the fish homolog of the predominant mammalian osmotic stress transcription factor nuclear factor of activated T-cells (NFAT5) also contributes to the activation of hyperosmolality inducible genes in cells of extremely euryhaline fish. However, in addition to NFAT5 the presence of other strong osmotically inducible signaling mechanisms is required for full activation of osmoregulated tilapia genes.
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Affiliation(s)
- Jens Hamar
- Department of Animal Sciences and Genome Center, University of California Davis, Davis, California, United States
| | - Avner Cnaani
- Department of Poultry and Aquaculture, Institute of Animal Sciences, Agricultural Research Organization, Rishon LeZion, Israel
| | - Dietmar Kültz
- Department of Animal Sciences and Genome Center, University of California Davis, Davis, California, United States
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Fuse S, Fujisawa H, Murao N, Iwata N, Watanabe T, Seino Y, Takeuchi H, Suzuki A, Sugimura Y. Effects of hypernatremia on the microglia. Peptides 2024; 179:171267. [PMID: 38908517 DOI: 10.1016/j.peptides.2024.171267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 06/07/2024] [Accepted: 06/19/2024] [Indexed: 06/24/2024]
Abstract
Signs and symptoms of hypernatremia largely indicate central nervous system dysfunction. Acute hypernatremia can cause demyelinating lesions similar to that observed in osmotic demyelination syndrome (ODS). We have previously demonstrated that microglia accumulate in ODS lesions and minocycline protects against ODS by inhibiting microglial activation. However, the direct effect of rapid rise in the sodium concentrations on microglia is largely unknown. In addition, the effect of chronic hypernatremia on microglia also remains elusive. Here, we investigated the effects of acute (6 or 24 h) and chronic (the extracellular sodium concentration was increased gradually for at least 7 days) high sodium concentrations on microglia using the microglial cell line, BV-2. We found that both acute and chronic high sodium concentrations increase NOS2 expression and nitric oxide (NO) production. We also demonstrated that the expression of nuclear factor of activated T-cells-5 (NFAT5) is increased by high sodium concentrations. Furthermore, NFAT5 knockdown suppressed NOS2 expression and NO production. We also demonstrated that high sodium concentrations decreased intracellular Ca2+ concentration and an inhibitor of Na+/Ca2+ exchanger, NCX, suppressed a decrease in intracellular Ca2+ concentrations and NOS2 expression and NO production induced by high sodium concentrations. Furthermore, minocycline inhibited NOS2 expression and NO production induced by high sodium concentrations. These in vitro data suggest that microglial activity in response to high sodium concentrations is regulated by NFAT5 and Ca2+ efflux through NCX and is suppressed by minocycline.
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Affiliation(s)
- Sachiho Fuse
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Haruki Fujisawa
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Naoya Murao
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Naoko Iwata
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Takashi Watanabe
- Division of Gene Regulation, Oncology Innovation Center, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yusuke Seino
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Hideyuki Takeuchi
- Department of Neurology and Stroke Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa 236-0004, Japan; Department of Neurology, Graduate School of Medicine, International University of Health and Welfare, Narita, Chiba 286-8686, Japan; Center for Intractable Neurological Diseases and Dementia, International University of Health and Welfare Atami Hospital, Atami, Shizuoka 413-0012, Japan
| | - Atsushi Suzuki
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yoshihisa Sugimura
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan.
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Fujisawa H, Watanabe T, Komine O, Fuse S, Masaki M, Iwata N, Murao N, Seino Y, Takeuchi H, Yamanaka K, Sawada M, Suzuki A, Sugimura Y. Prolonged extracellular low sodium concentrations and subsequent their rapid correction modulate nitric oxide production dependent on NFAT5 in microglia. Free Radic Biol Med 2024; 223:458-472. [PMID: 39155026 DOI: 10.1016/j.freeradbiomed.2024.08.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2024] [Revised: 08/14/2024] [Accepted: 08/15/2024] [Indexed: 08/20/2024]
Abstract
Hyponatremia is the most common clinical electrolyte disorder. Chronic hyponatremia has been recently reported to be associated with falls, fracture, osteoporosis, neurocognitive impairment, and mental manifestations. In the treatment of chronic hyponatremia, overly rapid correction of hyponatremia can cause osmotic demyelination syndrome (ODS), a central demyelinating disease that is also associated with neurological morbidity and mortality. Using a rat model, we have previously shown that microglia play a critical role in the pathogenesis of ODS. However, the direct effect of rapid correction of hyponatremia on microglia is unknown. Furthermore, the effect of chronic hyponatremia on microglia remains elusive. Using microglial cell lines BV-2 and 6-3, we show here that low extracellular sodium concentrations (36 mmol/L decrease; LS) suppress Nos2 mRNA expression and nitric oxide (NO) production of microglia. On rapid correction of low sodium concentrations, NO production was significantly increased in both cells, suggesting that acute correction of hyponatremia partly directly contributes to increased Nos2 mRNA expression and NO release in ODS pathophysiology. LS also suppressed expression and nuclear translocation of nuclear factor of activated T cells-5 (NFAT5), a transcription factor that regulates the expression of genes involved in osmotic stress. Furthermore, overexpression of NFAT5 significantly increased Nos2 mRNA expression and NO production in BV-2 cells. Expressions of Nos2 and Nfat5 mRNA were also modulated in microglia isolated from cerebral cortex in chronic hyponatremia model mice. These data indicate that LS modulates microglial NO production dependent on NFAT5 and suggest that microglia contribute to hyponatremia-induced neuronal dysfunctions.
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Affiliation(s)
- Haruki Fujisawa
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Takashi Watanabe
- Division of Gene Regulation, Oncology Innovation Center, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Okiru Komine
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8560, Japan
| | - Sachiho Fuse
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Momoka Masaki
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Naoko Iwata
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Naoya Murao
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Yusuke Seino
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Hideyuki Takeuchi
- Department of Neurology and Stroke Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, 236-0004, Japan; Department of Neurology, Graduate School of Medicine, International University of Health and Welfare, Narita, Chiba, 286-8686, Japan; Center for Intractable Neurological Diseases and Dementia, International University of Health and Welfare Atami Hospital, Atami, Shizuoka, 413-0012, Japan
| | - Koji Yamanaka
- Department of Neuroscience and Pathobiology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Neuroscience and Pathobiology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8560, Japan
| | - Makoto Sawada
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 464-8601, Japan
| | - Atsushi Suzuki
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Yoshihisa Sugimura
- Department of Endocrinology, Diabetes and Metabolism, School of Medicine, Fujita Health University, Toyoake, Aichi, 470-1192, Japan.
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Joshi P, Mohr F, Rumig C, Kliemank E, Krenning G, Kopf S, Hecker M, Wagner AH. Impact of the -1T>C single-nucleotide polymorphism of the CD40 gene on the development of endothelial dysfunction in a pro-diabetic microenvironment. Atherosclerosis 2024; 394:117386. [PMID: 38030458 DOI: 10.1016/j.atherosclerosis.2023.117386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/23/2023] [Accepted: 11/09/2023] [Indexed: 12/01/2023]
Abstract
BACKGROUND AND AIMS Hyperglycemia reinforces pro-inflammatory conditions that enhance CD40 expression in endothelial cells (EC). Thymine to cytosine transition (-1T > C) in the promoter of the CD40 gene (rs1883832) further increases the abundance of CD40 protein on the EC surface. This study examines potential associations of the -1T > C SNP of the CD40 gene with type 1 (T1D) or type 2 (T2D) diabetes. Moreover, it investigates the impact of a pro-inflammatory diabetic microenvironment on gene expression in human cultured umbilical vein EC (HUVEC) derived from CC- vs. TT-genotype donors. METHODS Tetra-ARMS-PCR was used to compare genotype distribution in 252 patients with diabetes. Soluble CD40 ligand (sCD40L) and soluble CD40 receptor (sCD40) plasma levels were monitored using ELISA. RNA-sequencing was performed with sCD40L-stimulated CC- and TT-genotype HUVEC. Quantitative PCR, Western blot, multiplex-sandwich ELISA array, and immunocytochemistry were used to analyse changes in gene expression in these cells. RESULTS Homozygosity for the C-allele was associated with a significant 4.3-fold higher odds of developing T2D as compared to individuals homozygous for the T-allele. Inflammation and endothelial-to-mesenchymal transition (EndMT) driving genes were upregulated in CC-genotype but downregulated in TT-genotype HUVEC when exposed to sCD40L. Expression of EndMT markers significantly increased while that of endothelial markers decreased in HUVEC following exposure to hyperglycemia, tumour necrosis factor-α and sCD40L. CONCLUSIONS The -1T > C SNP of the CD40 gene is a risk factor for T2D. Depending on the genotype, it differentially affects gene expression in human cultured EC. CC-genotype HUVEC adopt a pro-inflammatory and intermediate EndMT-like phenotype in a pro-diabetic microenvironment.
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Affiliation(s)
- Pooja Joshi
- Department of Cardiovascular Physiology, Heidelberg University, Germany
| | - Franziska Mohr
- Department of Cardiovascular Physiology, Heidelberg University, Germany
| | - Cordula Rumig
- Department of Cardiovascular Physiology, Heidelberg University, Germany
| | - Elisabeth Kliemank
- Department of Internal Medicine I, Heidelberg University Hospital, Germany
| | - Guido Krenning
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, the Netherlands
| | - Stefan Kopf
- Department of Internal Medicine I, Heidelberg University Hospital, Germany
| | - Markus Hecker
- Department of Cardiovascular Physiology, Heidelberg University, Germany
| | - Andreas H Wagner
- Department of Cardiovascular Physiology, Heidelberg University, Germany.
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Zhang J, Wang X, Li K, Rao W, Jiao X, Liang W, Gao H, Wang D, Cao Y, Wei X, Yang J. Hyperosmotic Stress Induces Inflammation and Excessive Th17 Response to Blunt T-Cell Immunity in Tilapia. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2024; 212:1877-1890. [PMID: 38700398 DOI: 10.4049/jimmunol.2300251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 03/29/2024] [Indexed: 05/05/2024]
Abstract
Despite the advances in study on osmotic physiology in bony fish, the mechanism by which the immune system, especially T-cell immunity, adapts and responds to osmotic stress remains unknown. In the current study, we investigated the response of T cells to hyperosmotic stress in the bony fish Nile tilapia (Oreochromis niloticus). As a euryhaline fish, tilapia was able to adapt to a wide range of salinities; however, hypertonic stress caused inflammation and excessive T-cell activation. Furthermore, hypertonic stress increased the expression of IL-17A in T cells, upregulated the transcription factor RORα, and activated STAT3 signaling, along with IL-6- and TGF-β1-mediated pathways, revealing an enhanced Th17 response in this early vertebrate. These hypertonic stress-induced events collectively resulted in an impaired antibacterial immune response in tilapia. Hypertonic stress elevated the intracellular ROS level, which in turn activated the p38-MK2 signaling pathway to promote IL-17A production by T cells. Both ROS elimination and the p38-MK2 axis blockade diminished the increased IL-17A production in T cells under hypertonic conditions. Moreover, the produced proinflammatory cytokines further amplified the hypertonic stress signaling via the MKK6-p38-MK2 axis-mediated positive feedback loop. To our knowledge, these findings represent the first description of the mechanism by which T-cell immunity responds to hypertonic stress in early vertebrates, thus providing a novel perspective for understanding the adaptive evolution of T cells under environmental stress.
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Affiliation(s)
- Jiansong Zhang
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Xiaodan Wang
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Kang Li
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Wenzhuo Rao
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Xinying Jiao
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Wei Liang
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Haiyou Gao
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Ding Wang
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Yi Cao
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Xiumei Wei
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
| | - Jialong Yang
- State Key Laboratory of Estuarine and Coastal Research, School of Life Sciences, East China Normal University, Shanghai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China
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ZHANG MINGCAI, CAMPBELL TANNER, FALCON SPENCER, WANG JINXI. Regulatory role of NFAT1 signaling in articular chondrocyte activities and osteoarthritis pathogenesis. BIOCELL 2023; 47:2125-2132. [PMID: 37974562 PMCID: PMC10651080 DOI: 10.32604/biocell.2023.030161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 07/26/2023] [Indexed: 11/19/2023]
Abstract
Osteoarthritis (OA), the most common form of joint disease, is characterized clinically by joint pain, stiffness, and deformity. OA is now considered a whole joint disease; however, the breakdown of the articular cartilage remains the major hallmark of the disease. Current treatments targeting OA symptoms have a limited impact on impeding or reversing the OA progression. Understanding the molecular and cellular mechanisms underlying OA development is a critical barrier to progress in OA therapy. Recent studies by the current authors' group and others have revealed that the nuclear factor of activated T cell 1 (NFAT1), a member of the NFAT family of transcription factors, regulates the expression of many anabolic and catabolic genes in articular chondrocytes of adult mice. Mice lacking NFAT1 exhibit normal skeletal development but display OA in both appendicular and spinal facet joints as adults. This review mainly focuses on the recent advances in the regulatory role of NFAT1 transcription factor in the activities of articular chondrocytes and its implication in the pathogenesis of OA.
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Affiliation(s)
- MINGCAI ZHANG
- Harrington Laboratory for Molecular Orthopedics, Department of Orthopedic Surgery, University of Kansas Medical Center, Kansas City, USA
| | - TANNER CAMPBELL
- Harrington Laboratory for Molecular Orthopedics, Department of Orthopedic Surgery, University of Kansas Medical Center, Kansas City, USA
| | - SPENCER FALCON
- Harrington Laboratory for Molecular Orthopedics, Department of Orthopedic Surgery, University of Kansas Medical Center, Kansas City, USA
| | - JINXI WANG
- Harrington Laboratory for Molecular Orthopedics, Department of Orthopedic Surgery, University of Kansas Medical Center, Kansas City, USA
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Crorkin P, Hao S, Ferreri NR. Responses to Ang II (Angiotensin II), Salt Intake, and Lipopolysaccharide Reveal the Diverse Actions of TNF-α (Tumor Necrosis Factor-α) on Blood Pressure and Renal Function. Hypertension 2022; 79:2656-2670. [PMID: 36129177 PMCID: PMC9649876 DOI: 10.1161/hypertensionaha.122.19464] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
TNF-α (tumor necrosis factor-alpha) is the best known as a proinflammatory cytokine; yet, this cytokine also has important immunomodulatory and regulatory functions. As the effects of TNF-α on immune system function were being revealed, the spectrum of its activities appeared in conflict with each other before investigators defined the settings and mechanisms by which TNF-α contributed to both host defense and chronic inflammation. These effects reflect self-protective mechanisms that may become harmful when dysregulated. The paradigm of physiological and pathophysiological effects of TNF-α has since been uncovered in the lung, colon, and kidney where its role has been identified in pulmonary edema, electrolyte reabsorption, and blood pressure regulation, respectively. Recent studies on the prohypertensive and inflammatory effects of TNF-α in the cardiovascular system juxtaposed to those related to NaCl and blood pressure homeostasis, the response of the kidney to lipopolysaccharide, and protection against bacterial infections are helping define the mechanisms by which TNF-α modulates distinct functions within the kidney. This review discusses how production of TNF-α by renal epithelial cells may contribute to regulatory mechanisms that not only govern electrolyte excretion and blood pressure homeostasis but also maintain the appropriate local hypersalinity environment needed for optimizing the innate immune response to bacterial infections in the kidney. It is possible that the wide range of effects mediated by TNF-α may be related to severity of disease, amount of inflammation and TNF-α levels, and the specific cell types that produce this cytokine, areas that remain to be investigated further.
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Affiliation(s)
- Patrick Crorkin
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Shoujin Hao
- Department of Pharmacology, New York Medical College, Valhalla, NY
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Snuggs JW, Tessier S, Bunning RAB, Shapiro IM, Risbud MV, Le Maitre CL. TonEBP regulates the hyperosmotic expression of aquaporin 1 and 5 in the intervertebral disc. Sci Rep 2021; 11:3164. [PMID: 33542263 PMCID: PMC7862284 DOI: 10.1038/s41598-021-81838-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/22/2020] [Indexed: 01/30/2023] Open
Abstract
The central region of the intervertebral disc (IVD) is rich in proteoglycans, leading to a hyperosmotic environment, which fluctuates with daily loading. The cells of the nucleus pulposus (NP cells) have adapted to this environment via the function of tonicity enhancer binding protein (TonEBP), and NP cells have been shown to express several water channels known as aquaporins (AQP). We have previously shown that AQP1 and 5 decrease during IVD degeneration. Here, the regulation of AQP1 and 5 by hyperosmotic conditions and the role of TonEBP in this regulation was investigated. AQP1 and 5 gene expression was upregulated by hyperosmotic conditions mimicking the osmolality of the healthy IVD, which was abrogated by TonEBP knockdown. Furthermore, AQP1 and 5 immunopositivity was significantly reduced in TonEBPΔ/Δ E17.5 mice when compared with wildtype controls, indicating in vivo expression of AQP1 and 5 is controlled at least in part by TonEBP. This hyperosmotic regulation of AQP1 and 5 could help to explain the decreased AQP1 and 5 expression during degeneration, when the osmolality of the NP decreases. Together this data suggests that TonEBP-regulated osmo-adaptation may be disrupted during IVD degeneration when the expression of both AQPs is reduced.
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Affiliation(s)
- J. W. Snuggs
- grid.5884.10000 0001 0303 540XBiomolecular Sciences Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield, S1 1WB UK
| | - S. Tessier
- grid.265008.90000 0001 2166 5843Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA USA
| | - R. A. B. Bunning
- grid.5884.10000 0001 0303 540XBiomolecular Sciences Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield, S1 1WB UK
| | - I. M. Shapiro
- grid.265008.90000 0001 2166 5843Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA USA ,grid.265008.90000 0001 2166 5843Graduate Program in Cell Biology and Regenerative Medicine, Thomas Jefferson University, Philadelphia, PA USA
| | - M. V. Risbud
- grid.265008.90000 0001 2166 5843Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA USA ,grid.265008.90000 0001 2166 5843Graduate Program in Cell Biology and Regenerative Medicine, Thomas Jefferson University, Philadelphia, PA USA
| | - C. L. Le Maitre
- grid.5884.10000 0001 0303 540XBiomolecular Sciences Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield, S1 1WB UK
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Huerga Encabo H, Traveset L, Argilaguet J, Angulo A, Nistal-Villán E, Jaiswal R, Escalante CR, Gekas C, Meyerhans A, Aramburu J, López-Rodríguez C. The transcription factor NFAT5 limits infection-induced type I interferon responses. J Exp Med 2020; 217:132619. [PMID: 31816635 PMCID: PMC7062515 DOI: 10.1084/jem.20190449] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 09/23/2019] [Accepted: 11/07/2019] [Indexed: 12/20/2022] Open
Abstract
Huerga Encabo et al. show that NFAT5, previously characterized as a pro-inflammatory transcription factor, limits the IFN-I response to control antiviral defenses and preserve HSC quiescence. NFAT5 represses IFN-I and ISG expression through an evolutionarily conserved DNA element that prevents IRF3 recruitment to the IFNB1 enhanceosome. Type I interferon (IFN-I) provides effective antiviral immunity but can exacerbate harmful inflammatory reactions and cause hematopoietic stem cell (HSC) exhaustion; therefore, IFN-I expression must be tightly controlled. While signaling mechanisms that limit IFN-I induction and function have been extensively studied, less is known about transcriptional repressors acting directly on IFN-I regulatory regions. We show that NFAT5, an activator of macrophage pro-inflammatory responses, represses Toll-like receptor 3 and virus-induced expression of IFN-I in macrophages and dendritic cells. Mice lacking NFAT5 exhibit increased IFN-I production and better control of viral burden upon LCMV infection but show exacerbated HSC activation under systemic poly(I:C)-induced inflammation. We identify IFNβ as a primary target repressed by NFAT5, which opposes the master IFN-I inducer IRF3 by binding to an evolutionarily conserved sequence in the IFNB1 enhanceosome that overlaps a key IRF site. These findings illustrate how IFN-I responses are balanced by simultaneously opposing transcription factors.
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Affiliation(s)
- Hector Huerga Encabo
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Laia Traveset
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Jordi Argilaguet
- Infection Biology Laboratory, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Ana Angulo
- Immunology Unit, Department of Biomedical Sciences, Medical School, University of Barcelona, Barcelona, Spain
| | - Estanislao Nistal-Villán
- Microbiology Section, Departamento de Ciencias, Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU San Pablo, CEU Universities, Madrid, Spain
| | - Rahul Jaiswal
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Carlos R Escalante
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Christos Gekas
- Program in Cancer Research, Institut Hospital del Mar d'Investigacions Mèdiques, Barcelona, Spain
| | - Andreas Meyerhans
- Infection Biology Laboratory, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - Jose Aramburu
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Cristina López-Rodríguez
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
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10
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Abnormal NFAT5 Physiology in Duchenne Muscular Dystrophy Fibroblasts as a Putative Explanation for the Permanent Fibrosis Formation in Duchenne Muscular Dystrophy. Int J Mol Sci 2020; 21:ijms21217888. [PMID: 33114289 PMCID: PMC7660673 DOI: 10.3390/ijms21217888] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/19/2020] [Accepted: 10/21/2020] [Indexed: 12/29/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is characterized by chronic inflammation and fibrotic tissue production by fibroblasts. The promyogenic factor nuclear factor of activated T-cells 5 (NFAT5) is virtually present in all cells, responding to hyperosmolar or pro-inflammatory stress. In embryogenic fibroblasts, absence of NFAT5 results in cell cycle arrest. Here, unaffected skeletal muscle fibroblasts from one healthy donor showed NFAT5 nuclear translocation upon hyperosmolar stress and normal cell viability. Absence of NFAT5 translocation under pro-inflammatory conditions resulted in decreased cell growth (Incucyte ZOOM). In DMD skeletal muscle fibroblasts from one DMD patient, NFAT5 was merely located in the nucleus. Exposure to hyperosmolar conditions or pro-inflammatory cytokines IFN-γ, IL-1β and TNF-α had no influence on NFAT5 physiology (immunofluorescence, western blotting, RT-qPCR). Hyperosmolarity resulted in decreased cell viability and pro-inflammatory stress in unaltered cell growth. These findings suggest that NFAT5 is vital to DMD fibroblast survival. Exposure to pro-inflammatory or hyperosmolar stress in DMD fibroblasts results in an unexpected NFAT5 response, where fibroblasts are not triggered by inflammatory cytokines and do not withstand hyperosmolarity. Chronic inflammation could be viewed as a non-restrictive factor in the formation of fibrosis in DMD. Abnormal NFAT5 physiology could provide a molecular explanation for permanent fibrotic matrix production by DMD fibroblasts.
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11
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Madonna R, Pieragostino D, Rossi C, Confalone P, Cicalini I, Minnucci I, Zucchelli M, Del Boccio P, De Caterina R. Simulated hyperglycemia impairs insulin signaling in endothelial cells through a hyperosmolar mechanism. Vascul Pharmacol 2020; 130:106678. [DOI: 10.1016/j.vph.2020.106678] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 02/18/2020] [Accepted: 03/25/2020] [Indexed: 12/24/2022]
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12
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Minshawi F, White MRH, Muller W, Humphreys N, Jackson D, Campbell BJ, Adamson A, Papoutsopoulou S. Human TNF-Luc reporter mouse: A new model to quantify inflammatory responses. Sci Rep 2019; 9:193. [PMID: 30655563 PMCID: PMC6336827 DOI: 10.1038/s41598-018-36969-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 11/19/2018] [Indexed: 12/26/2022] Open
Abstract
Tumour necrosis factor (TNF) is a key cytokine during inflammatory responses and its dysregulation is detrimental in many inflammatory diseases, such as rheumatoid arthritis and inflammatory bowel disease. Here, we used a bacterial artificial chromosome (BAC) construct that expresses luciferase under the control of the human TNF locus to generate a novel transgenic mouse, the hTNF.LucBAC strain. In vitro stimulation of hTNF.LucBAC cells of different origin revealed a cell specific response to stimuli demonstrating the integrated construct's ability as a proxy for inflammatory gene response. Lipopolysaccharide was the most potent luciferase inducer in macrophages, while TNF was a strong activator in intestinal organoids. Lipopolysaccharide-induced luciferase activity in macrophages was downregulated by inhibitors of NF-κB pathway, as well as by Interleukin-10, a known anti-inflammatory cytokine. Moreover, the transgene-dependent luciferase activity showed a positive correlation to the endogenous murine soluble TNF secreted to the culture medium. In conclusion, the hTNF.LucBAC strain is a valuable tool for studying and screening molecules that target TNF synthesis and will allow further functional studies of the regulatory elements of the TNF locus.
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Affiliation(s)
- Faisal Minshawi
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester, M13 9PT, United Kingdom.,Department of Laboratory Medicine, Faculty of Applied Medical Science, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Mike R H White
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester, M13 9PT, United Kingdom
| | - Werner Muller
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester, M13 9PT, United Kingdom
| | - Neil Humphreys
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester, M13 9PT, United Kingdom
| | - Dean Jackson
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester, M13 9PT, United Kingdom
| | - Barry J Campbell
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, L69 3GE, United Kingdom
| | - Antony Adamson
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester, M13 9PT, United Kingdom.
| | - Stamatia Papoutsopoulou
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester, M13 9PT, United Kingdom. .,Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, L69 3GE, United Kingdom.
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13
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Yang XL, Wang X, Peng BW. NFAT5 Has a Job in the Brain. Dev Neurosci 2018; 40:289-300. [PMID: 30391952 DOI: 10.1159/000493789] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/14/2018] [Indexed: 11/19/2022] Open
Abstract
Nuclear factor of activated T cells 5 (NFAT5) has recently been classified as a new member of the Rel family. In addition, there are 5 more well-defined members (NF-κB and NFAT1-4) in the Rel family, which participate in regulating the expression of immune and inflammatory response-related genes. NFAT5 was initially identified in renal medullary cells where it regulated the expression of osmoprotective-related genes during the osmotic response. Many studies have demonstrated that NFAT5 is highly expressed in the nuclei of neurons in fetal and adult brains. Additionally, its expression is approximately 10-fold higher in fetal brains. With the development of detection technologies (laser scanning confocal microscopy, transgene technology, etc.), recent studies suggest that NFAT5 is also expressed in glial cells and plays a more diverse functional role. This article aims to summarize the current knowledge regarding the expression of NFAT5, its regulation of activation, and varied biological functions in the brain.
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Affiliation(s)
- Xing-Liang Yang
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Xin Wang
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Bi-Wen Peng
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan, China,
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14
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Herbelet S, De Vlieghere E, Gonçalves A, De Paepe B, Schmidt K, Nys E, Weynants L, Weis J, Van Peer G, Vandesompele J, Schmidt J, De Wever O, De Bleecker JL. Localization and Expression of Nuclear Factor of Activated T-Cells 5 in Myoblasts Exposed to Pro-inflammatory Cytokines or Hyperosmolar Stress and in Biopsies from Myositis Patients. Front Physiol 2018. [PMID: 29515464 PMCID: PMC5826317 DOI: 10.3389/fphys.2018.00126] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Aims: Regeneration in skeletal muscle relies on regulated myoblast migration and differentiation, in which the transcription factor nuclear factor of activated T-cells 5 (NFAT5) participates. Impaired muscle regeneration and chronic inflammation are prevalent in myositis. Little is known about the impact of inflammation on NFAT5 localization and expression in this group of diseases. The goal of this study was to investigate NFAT5 physiology in unaffected myoblasts exposed to cytokine or hyperosmolar stress and in myositis. Methods: NFAT5 intracellular localization and expression were studied in vitro using a cell culture model of myositis. Myoblasts were exposed to DMEM solutions enriched with pro-inflammatory cytokines IFN-γ with IL-1β or hyperosmolar DMEM obtained by NaCl supplementation. NFAT5 localization was visualized using immunohistochemistry (IHC) and Western blotting (WB) in fractionated cell lysates. NFAT5 expression was assessed by WB and RT-qPCR. In vivo localization and expression of NFAT5 were studied in muscle biopsies of patients diagnosed with polymyositis (n = 6), dermatomyositis (n = 10), inclusion body myositis (n = 11) and were compared to NFAT5 localization and expression in non-myopathic controls (n = 13). Muscle biopsies were studied by means of quantitative IHC and WB of total protein extracts. Results: In unaffected myoblasts, hyperosmolar stress ensues in NFAT5 nuclear translocation and increased NFAT5 mRNA and protein expression. In contrast, pro-inflammatory cytokines did not lead to NFAT5 nuclear translocation nor increased expression. Cytokines IL-1β with IFN-γ induced colocalization of NFAT5 with histone deacetylase 6 (HDAC6), involved in cell motility. In muscle biopsies from dermatomyositis and polymyositis patients, NFAT5 colocalized with HDAC6, while in IBM, this was often absent. Conclusions: Our data suggest impaired NFAT5 localization and expression in unaffected myoblasts in response to inflammation. This disturbed myogenic NFAT5 physiology could possibly explain deleterious effects on muscle regeneration in myositis.
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Affiliation(s)
- Sandrine Herbelet
- Department of Neurology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Elly De Vlieghere
- Cancer Research Institute Ghent and Department of Radiation Oncology and Experimental Cancer Research, Ghent University, Ghent, Belgium
| | - Amanda Gonçalves
- VIB Inflammation Research Center, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.,VIB Bio Imaging Core Gent, Ghent, Belgium
| | - Boel De Paepe
- Department of Neurology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Karsten Schmidt
- Department of Neurology and Department of Experimental and Clinical Neuroimmunology, University of Göttingen, Göttingen, Germany
| | - Eline Nys
- Department of Neurology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Laurens Weynants
- Department of Neurology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen Medical School, Aachen, Germany
| | - Gert Van Peer
- Center for Medical Genetics and Cancer Research Institute Ghent, Ghent, Belgium
| | - Jo Vandesompele
- Center for Medical Genetics and Cancer Research Institute Ghent, Ghent, Belgium
| | - Jens Schmidt
- Department of Neurology and Department of Experimental and Clinical Neuroimmunology, University of Göttingen, Göttingen, Germany
| | - Olivier De Wever
- Cancer Research Institute Ghent and Department of Radiation Oncology and Experimental Cancer Research, Ghent University, Ghent, Belgium
| | - Jan L De Bleecker
- Department of Neurology, Ghent University and Ghent University Hospital, Ghent, Belgium
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15
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Cleavage of osmosensitive transcriptional factor NFAT5 by Coxsackieviral protease 2A promotes viral replication. PLoS Pathog 2017; 13:e1006744. [PMID: 29220410 PMCID: PMC5738146 DOI: 10.1371/journal.ppat.1006744] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 12/20/2017] [Accepted: 11/10/2017] [Indexed: 12/16/2022] Open
Abstract
Nuclear factor of activated T cells 5 (NFAT5)/Tonicity enhancer binding protein (TonEBP) is a transcription factor induced by hypertonic stress in the kidney. However, the function of NFAT5 in other organs has rarely been studied, even though it is ubiquitously expressed. Indeed, although NFAT5 was reported to be critical for heart development and function, its role in infectious heart diseases has remained obscure. In this study, we aimed to understand the mechanism by which NFAT5 interferes with infection of Coxsackievirus B3 (CVB3), a major cause of viral myocarditis. Our initial results demonstrated that although the mRNA level of NFAT5 remained constant during CVB3 infection, NFAT5 protein level decreased because the protein was cleaved. Bioinformatic prediction and verification of the predicted site by site-directed mutagenesis experiments determined that the NFAT5 protein was cleaved by CVB3 protease 2A at Glycine 503. Such cleavage led to the inactivation of NFAT5, and the 70-kDa N-terminal cleavage product (p70-NFAT5) exerted a dominant negative effect on the full-length NFAT5 protein. We further showed that elevated expression of NFAT5 to counteract viral protease cleavage, especially overexpression of a non-cleavable mutant of NFAT5, significantly inhibited CVB3 replication. Ectopic expression of NFAT5 resulted in elevated expression of inducible nitric oxide synthase (iNOS), a factor reported to inhibit CVB3 replication. The necessity of iNOS for the anti-CVB3 effect of NFAT5 was supported by the observation that inhibition of iNOS blocked the anti-CVB3 effect of NFAT5. In a murine model of viral myocarditis, we observed that treatment with hypertonic saline or mannitol solution upregulated NFAT5 and iNOS expression, inhibited CVB3 replication and reduced tissue damage in the heart. Taken together, our data demonstrate that the anti-CVB3 activity of NFAT5 is impaired during CVB3 infection due to 2A-mediated cleavage of NFAT5. Thus induction of NFAT5 by hypertonic agents may be a promising strategy for the development of anti-CVB3 therapeutics.
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16
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Aker L, Ghannam M, Alzuabi MA, Jumah F, Alkhdour SM, Mansour S, Samara A, Cronk K, Massengale J, Holsapple J, Adeeb N, Oskouian RJ, Tubbs RS. Molecular Biology and Interactions in Intervertebral Disc Development, Homeostasis, and Degeneration, with Emphasis on Future Therapies: A Systematic Review. ACTA ACUST UNITED AC 2017. [DOI: 10.26632/ss.3.2017.1.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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17
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Bittner S, Knoll G, Ehrenschwender M. Hyperosmotic stress enhances cytotoxicity of SMAC mimetics. Cell Death Dis 2017; 8:e2967. [PMID: 28771230 PMCID: PMC5596546 DOI: 10.1038/cddis.2017.355] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/26/2017] [Accepted: 07/03/2017] [Indexed: 01/10/2023]
Abstract
Inhibitors of apoptosis (IAP) proteins contribute to cell death resistance in malignancies and emerged as promising targets in cancer therapy. Currently, small molecules mimicking the IAP-antagonizing activity of endogenous second mitochondria-derived activator of caspases (SMAC) are evaluated in phase 1/2 clinical trials. In cancer cells, SMAC mimetic (SM)-mediated IAP depletion induces tumor necrosis factor (TNF) secretion and simultaneously sensitizes for TNF-induced cell death. However, tumor cells lacking SM-induced autocrine TNF release survive and thus limit therapeutic efficacy. Here, we show that hyperosmotic stress boosts SM cytotoxicity in human and murine cells through hypertonicity-induced upregulation of TNF with subsequent induction of apoptosis and/or necroptosis. Hypertonicity allowed robust TNF-dependent killing in SM-treated human acute lymphoblastic leukemia cells, which under isotonic conditions resisted SM treatment due to poor SM-induced TNF secretion. Mechanistically, hypertonicity-triggered TNF release bypassed the dependency on SM-induced TNF production to execute SM cytotoxicity, effectively reducing the role of SM to TNF-sensitizing, but not necessarily TNF-inducing agents. Perspectively, these findings could extend the clinical application of SM.
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Affiliation(s)
- Sebastian Bittner
- Institute of Clinical Microbiology and Hygiene, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, Regensburg 93053, Germany
| | - Gertrud Knoll
- Institute of Clinical Microbiology and Hygiene, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, Regensburg 93053, Germany
| | - Martin Ehrenschwender
- Institute of Clinical Microbiology and Hygiene, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, Regensburg 93053, Germany
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18
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Guo JY, Li F, Wen YB, Cui HX, Guo ML, Zhang L, Zhang YF, Guo YJ, Guo YX. Melatonin inhibits Sirt1-dependent NAMPT and NFAT5 signaling in chondrocytes to attenuate osteoarthritis. Oncotarget 2017; 8:55967-55983. [PMID: 28915567 PMCID: PMC5593538 DOI: 10.18632/oncotarget.18356] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/12/2017] [Indexed: 12/24/2022] Open
Abstract
Osteoarthritis (OA) is a degenerative joint disease mainly characterized by cartilage degradation. Interleukin-1β (IL-1β) contributes to OA pathogenesis by enhancing oxidative stress and inflammation. Melatonin reportedly elicits potent protection against OA. However, the role of melatonin and underlying mechanism in IL-1β-stimulated chondrocytes remain largely unclear. In this study, we found that melatonin inhibited IL-1β-induced toxicity and sirtuin 1 (Sirt1) enhancement in human chondrocytes. Melatonin reduced the IL-1β-increased nicotinamide phosphoribosyltransferase (NAMPT) expression and the NAD+ level in chondrocytes in a Sirt1-dependent manner. In turn, the inhibitory effect of melatonin on Sirt1 was mediated by NAMPT. Moreover, melatonin suppressed IL-1β-induced Sirt1-mediated matrix metalloproteinase (MMP)-3 and MMP-13 production. Melatonin also decreased the Sirt1-steered nuclear factor of activated T cells 5 (NFAT5) expression in IL-1β-challenged chondrocytes. NFAT5 depletion mimicked the suppressive effects of melatonin on IL-1β-elevated production of inflammatory mediators, including tumor necrosis factor-α (TNF-α), IL-1β, prostaglandin E2 (PGE2), and nitric oxide (NO) in chondrocytes. TNF-α, IL-1β, PGE2, or NO decrease caused the similar reduction of MMP-3 and MMP-13 by melatonin in IL-1β-insulted chondrocytes. Highly consistent with in vitro findings, in vivo results demonstrated that melatonin repressed the expression of relevant genes in rat OA pathogenesis in anterior cruciate ligament transection model. Overall, these results indicate that melatonin effectively reduced IL-1β-induced MMP production by inhibiting Sirt1-dependent NAMPT and NFAT5 signaling in chondrocytes, suggesting melatonin as a potential therapeutic alternative for chondroprotection of OA patients.
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Affiliation(s)
- Jia Yi Guo
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
| | - Feng Li
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
| | - Yong Bing Wen
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
| | - Hong Xun Cui
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
| | - Ma Long Guo
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
| | - Lin Zhang
- Department of Surgery, Advanced Clinical Skills Centre, University of Auckland, Auckland, New Zealand
| | - Yun Fei Zhang
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
| | - Yan Jin Guo
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
| | - Yan Xing Guo
- Luoyang Orthopedic Hospital of Henan Province, Luoyang, Henan, China
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19
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Madonna R, Balistreri CR, Geng YJ, De Caterina R. Diabetic microangiopathy: Pathogenetic insights and novel therapeutic approaches. Vascul Pharmacol 2017; 90:1-7. [PMID: 28137665 DOI: 10.1016/j.vph.2017.01.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 01/26/2017] [Indexed: 12/11/2022]
Abstract
Diabetic microangiopathy, including retinopathy, is characterized by abnormal growth and leakage of small blood vessels, resulting in local edema and functional impairment of the depending tissues. Mechanisms leading to the impairment of microcirculation in diabetes are multiple and still largely unclear. However, a dysregulated vascular regeneration appears to play a key role. In addition, oxidative and hyperosmolar stress, as well as the activation of inflammatory pathways triggered by advanced glycation end-products and toll-like receptors, have been recognized as key underlying events. Here, we review recent knowledge on cellular and molecular pathways of microvascular disease in diabetes. We also highlight how new insights into pathogenic mechanisms of vascular damage in diabetes may indicate new targets for prevention and treatment.
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Affiliation(s)
- Rosalinda Madonna
- Center of Excellence on Aging (CesiMet), Institute of Cardiology, Department of Neurosciences, Imaging and Clinical Sciences, "G. d'Annunzio" University, Chieti, Italy; The Texas Heart Institute, Center for Cardiovascular Biology and Atherosclerosis Research, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Carmela Rita Balistreri
- Department of Pathobiology and Medical Biotechnologies, University of Palermo, Palermo, Italy
| | - Yong-Jian Geng
- The Texas Heart Institute, Center for Cardiovascular Biology and Atherosclerosis Research, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Raffaele De Caterina
- Center of Excellence on Aging (CesiMet), Institute of Cardiology, Department of Neurosciences, Imaging and Clinical Sciences, "G. d'Annunzio" University, Chieti, Italy.
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20
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De Paepe B. A recipe for myositis: nuclear factor κB and nuclear factor of activated T-cells transcription factor pathways spiced up by cytokines. AIMS ALLERGY AND IMMUNOLOGY 2017. [DOI: 10.3934/allergy.2017.1.31] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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21
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Johnson ZI, Shapiro IM, Risbud MV. RNA Sequencing Reveals a Role of TonEBP Transcription Factor in Regulation of Pro-inflammatory Genes in Response to Hyperosmolarity in Healthy Nucleus Pulposus Cells: A HOMEOSTATIC RESPONSE? J Biol Chem 2016; 291:26686-26697. [PMID: 27875309 DOI: 10.1074/jbc.m116.757732] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/12/2016] [Indexed: 11/06/2022] Open
Abstract
Transcription factor tonicity-responsive enhancer-binding protein (TonEBP/NFAT5) is critical for osmo-adaptation and extracellular matrix homeostasis of nucleus pulposus (NP) cells in their hypertonic tissue niche. Recent studies implicate TonEBP signaling in inflammatory disease and rheumatoid arthritis pathogenesis. However, broader functions of TonEBP in the disc remain unknown. RNA sequencing was performed on NP cells with TonEBP knockdown under hypertonic conditions. 1140 TonEBP-dependent genes were identified and categorized using Ingenuity Pathway Analysis. Bioinformatic analysis showed enrichment of matrix homeostasis and cytokine/chemokine signaling pathways. C-C motif chemokine ligand 2 (CCL2), interleukin 6 (IL6), tumor necrosis factor (TNF), and nitric oxide synthase 2 (NOS2) were studied further. Knockdown experiments showed that TonEBP was necessary to maintain expression levels of these genes. Gain- and loss-of-function experiments and site-directed mutagenesis demonstrated that TonEBP binding to a specific site in the CCL2 promoter is required for hypertonic inducibility. Despite inhibition by dominant-negative TonEBP, IL6 and NOS2 promoters were not hypertonicity-inducible. Whole-disc response to hypertonicity was studied in an ex vivo organ culture model, using wild-type and haploinsufficient TonEBP mice. Pro-inflammatory targets were induced by hypertonicity in discs from wild-type but not TonEBP-haploinsufficient mice. Mechanistically, NF-κB activity increased with hypertonicity and was necessary for hypertonic induction of target genes IL6, TNF, and NOS2 but not CCL2 Although TonEBP maintains transcription of genes traditionally considered pro-inflammatory, it is important to note that some of these genes also serve anabolic and pro-survival roles. Therefore, in NP cells, this phenomenon may reflect a physiological adaptation to diurnal osmotic loading of the intervertebral disc.
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Affiliation(s)
- Zariel I Johnson
- Graduate Program in Cell and Developmental Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Irving M Shapiro
- Graduate Program in Cell and Developmental Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.,From the Department of Orthopaedic Surgery and
| | - Makarand V Risbud
- Graduate Program in Cell and Developmental Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 .,From the Department of Orthopaedic Surgery and
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22
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Küper C, Beck FX, Neuhofer W. Autocrine MCP-1/CCR2 signaling stimulates proliferation and migration of renal carcinoma cells. Oncol Lett 2016; 12:2201-2209. [PMID: 27602164 DOI: 10.3892/ol.2016.4875] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 05/13/2016] [Indexed: 12/31/2022] Open
Abstract
The chemokine monocyte chemoattractant protein-1 [MCP-1; also known as chemokine (C-C motif) ligand 2] is an important mediator of monocyte recruitment during inflammatory processes. Pathologically high expression levels of MCP-1 by tumor cells have been observed in a variety of cancer types. In the majority of cases, high MCP-1 expression is associated with a poor prognosis, as infiltration of the tumor with inflammatory monocytes promotes tumor progression and metastasis. MCP-1 is also expressed in renal cell carcinoma (RCC). In the present study, the function and the regulation of MCP-1 was investigated in two RCC cell lines, CaKi-1 and 786-O. In both cell lines, expression of MCP-1 was significantly enhanced compared with non-cancerous control cells. As expected, secretion of MCP-1 into the medium facilitated the recruitment of peripheral blood monocytes via the chemokine (C-C motif) receptor type 2 (CCR2). As expression of CCR2 was also detected in 786-O and CaKi-1 cells, the effect of autocrine MCP-1/CCR2 signaling was evaluated in these cells. In proliferation assays, administration of an MCP-1 neutralizing antibody or of a CCR2 antagonist to CaKi-1 and 786-O cells significantly decreased cell growth; supplementation of the growth medium with recombinant human MCP-1 had no additional effect on proliferation. The migration ability of RCC cells was impaired by MCP-1 neutralization or pharmacological CCR2 inhibition, while it was stimulated by the addition of recombinant human MCP-1, compared with untreated control cells. Finally, substantial differences in the regulation of MCP-1 expression were observed between RCC cell lines. In CaKi-1 cells, expression of MCP-1 appears to be largely mediated by the transcription factor nuclear factor of activated T cells 5, while in 786-O cells, deletion of the tumor suppressor gene Von-Hippel-Lindau appeared to be responsible for MCP-1 upregulation, as suggested by previous studies. Taken together, the results of the current study indicate that expression of MCP-1 in RCC cells promotes tumor progression and metastasis not only by paracrine, but also by autocrine, MCP-1/CCR2 signaling events, enhancing cell proliferation and migration ability. Therefore, the present findings suggest the MCP-1/CCR2 axis is a potential target for future therapeutic strategies in the treatment of metastatic RCC.
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Affiliation(s)
- Christoph Küper
- Department of Physiology, University of Munich, D-80336 Munich, Germany
| | - Franz-Xaver Beck
- Department of Physiology, University of Munich, D-80336 Munich, Germany
| | - Wolfgang Neuhofer
- Division of Nephrology and Rheumatology, Clinical Center Traunstein, D-83278 Traunstein, Germany
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23
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Park MH, Park E, Kim HJ, Na HS, Chung J. Porphyromonas gingivalis-induced miR-132 regulates TNFα expression in THP-1 derived macrophages. SPRINGERPLUS 2016; 5:761. [PMID: 27386246 PMCID: PMC4912528 DOI: 10.1186/s40064-016-2363-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/18/2016] [Indexed: 01/07/2023]
Abstract
Background Periodontitis is a chronic inflammatory disease induced by periodontopathogens such as Porphyromonas gingivalis (P. gingivalis). MicroRNAs (miRNAs) are small single-stranded noncoding RNAs that regulate gene expression at the level of translation. MiRNAs have been reported to be involved in inflammatory processes. In this study, we examined the effects of P. gingivalis-induced inflammatory miRNAs expression on TNFα production in THP-1 derived macrophages. Results Porphyromonas gingivalis induced the expression of miR-132. P. gingivalis-induced miR-132 expression was significantly inhibited by TLR2/4 knock-down and NF-κB inhibitor. Additionally, miR-132 antagomir strongly repressed production of TNFα. The expression of NFE2L2 and NFAT5, the putative target genes of miR-132 involved in regulation of TNFα, decreased in response to P. gingivalis. Furthermore, miR-132 antagomir rescued P. gingivalis-induced suppression of NFE2L2 and NFAT5. Conclusions These results suggest that the induction of miR-132 by P. gingivalis can modulate the pathogenesis of periodontitis induced via regulatory expression of TNFα.
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Affiliation(s)
- Mi Hee Park
- Department of Oral Microbiology, School of Dentistry, Pusan National University, Yangsan-si, Gyeongsangnam-do 626-870 South Korea
| | - Eunjoo Park
- Department of Oral Microbiology, School of Dentistry, Pusan National University, Yangsan-si, Gyeongsangnam-do 626-870 South Korea
| | - Hyung-Joon Kim
- Department of Oral Physiology, School of Dentistry, Pusan National University, Yangsan-si, 626-870 South Korea
| | - Hee Sam Na
- Department of Oral Microbiology, School of Dentistry, Pusan National University, Yangsan-si, Gyeongsangnam-do 626-870 South Korea
| | - Jin Chung
- Department of Oral Microbiology, School of Dentistry, Pusan National University, Yangsan-si, Gyeongsangnam-do 626-870 South Korea
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Cell cycle and apoptosis regulation by NFAT transcription factors: new roles for an old player. Cell Death Dis 2016; 7:e2199. [PMID: 27100893 PMCID: PMC4855676 DOI: 10.1038/cddis.2016.97] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/13/2016] [Accepted: 03/16/2016] [Indexed: 12/11/2022]
Abstract
The NFAT (nuclear factor of activated T cells) family of transcription factors consists of four Ca2+-regulated members (NFAT1–NFAT4), which were first described in T lymphocytes. In addition to their well-documented role in T lymphocytes, where they control gene expression during cell activation and differentiation, NFAT proteins are also expressed in a wide range of cells and tissue types and regulate genes involved in cell cycle, apoptosis, angiogenesis and metastasis. The NFAT proteins share a highly conserved DNA-binding domain (DBD), which allows all NFAT members to bind to the same DNA sequence in enhancers or promoter regions. The same DNA-binding specificity suggests redundant roles for the NFAT proteins, which is true during the regulation of some genes such as IL-2 and p21. However, it has become increasingly clear that different NFAT proteins and even isoforms can have unique functions. In this review, we address the possible reasons for these distinct roles, particularly regarding N- and C-terminal transactivation regions (TADs) and the partner proteins that interact with these TADs. We also discuss the genes regulated by NFAT during cell cycle regulation and apoptosis and the role of NFAT during tumorigenesis.
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Madonna R, Giovannelli G, Confalone P, Renna FV, Geng YJ, De Caterina R. High glucose-induced hyperosmolarity contributes to COX-2 expression and angiogenesis: implications for diabetic retinopathy. Cardiovasc Diabetol 2016; 15:18. [PMID: 26822858 PMCID: PMC4731895 DOI: 10.1186/s12933-016-0342-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/22/2016] [Indexed: 12/26/2022] Open
Abstract
Background We tested the hypothesis that glucose-induced hyperosmolarity, occurring in diabetic hyperglycemia, promotes retinal angiogenesis, and that interference with osmolarity signaling ameliorates excessive angiogenesis and retinopathy in vitro and in vivo. Methods and Results We incubated human aortic (HAECs) and dermal microvascular endothelial cells (HMVECs) with glucose or mannitol for 24 h and tested them for protein levels and in vitro angiogenesis. We used the Ins2 Akita mice as a model of type 1 diabetes to test the in vivo relevance of in vitro observations. Compared to incubations with normal (5 mmol/L) glucose concentrations, cells exposed to both high glucose and high mannitol (at 30.5 or 50.5 mmol/L) increased expression of the water channel aquaporin-1 (AQP1) and cyclooxygenase (COX)-2. This was preceded by increased activity of the osmolarity-sensitive transcription factor Tonicity enhancer binding protein (TonEBP), and enhanced endothelial migration and tubulization in Matrigel, reverted by treatment with AQP1 and TonEBP siRNA. Retinas of Ins2 Akita mice showed increased levels of AQP1 and COX-2, as well as angiogenesis, all reverted by AQP1 siRNA intravitreal injections. Conclusions Glucose-related hyperosmolarity seems to be able to promote angiogenesis and retinopathy through activation of TonEBP and possibly increasing expression of AQP1 and COX-2. Osmolarity signaling may be a target for therapy.
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Affiliation(s)
- Rosalinda Madonna
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy. .,The University of Texas Health Science Center at Houston and the Texas Heart Institute, Houston, TX, USA.
| | - Gaia Giovannelli
- Department of Neurosciences and Imaging, "G. d'Annunzio" University, Chieti, Italy.
| | - Pamela Confalone
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy.
| | - Francesca Vera Renna
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy.
| | - Yong-Jian Geng
- The University of Texas Health Science Center at Houston and the Texas Heart Institute, Houston, TX, USA.
| | - Raffaele De Caterina
- Laboratory of Experimental Cardiology, Center of Excellence on Aging, Institute of Cardiology, "G. d'Annunzio" University, C/o Ospedale SS. Annunziata, Via dei Vestini, 31, 66013, Chieti, Italy.
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Abstract
High extracellular NaCl is known to change expression of numerous genes, many of which are regulated by the osmoprotective transcription factor nuclear factor of activated T cells-5 (NFAT5). In the present study we employed RNA-Seq to provide a comprehensive, unbiased account of genes regulated by high NaCl in mouse embryonic fibroblast cells (MEFs). To identify genes regulated by NFAT5 we compared wild-type MEFs (WT-MEFs) to MEFs in which mutation of the NFAT5 gene inhibits its transcriptional activity (Null-MEFs). In WT-MEFs adding NaCl to raise osmolality from 300 to 500 mosmol/kg for 24 h increases expression of 167 genes and reduces expression of 412. Raising osmolality through multiple passages (adapted cells) increases expression of 196 genes and reduces expression of 528. In Null-MEFs, after 24 h of high NaCl, expression of 217 genes increase and 428 decrease, while in adapted Null-MEFs 143 increase and 622 decrease. Fewer than 10% of genes are regulated in common between WT- and null-MEFs, indicating a profound difference in regulation of high-NaCl induced genes induced by NFAT5 compared with those induced in the absence of NFAT5. Based on our findings we suggest a mechanism for this phenomenon, which had previously been unexplained. The NFAT5 DNA-binding motif (osmotic response element) is overrepresented in the vicinity of genes that NFAT5 upregulates, but not genes that it downregulates. We used Gene Ontology and manual curation to determine the function of the genes targeted by NFAT5, revealing many novel consequences of NFAT5 transcriptional activity.
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Affiliation(s)
- Yuichiro Izumi
- Systems Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Wenjing Yang
- Systems Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Jun Zhu
- Systems Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Maurice B Burg
- Systems Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Joan D Ferraris
- Systems Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Caldwell KL, Wang J. Cell-based articular cartilage repair: the link between development and regeneration. Osteoarthritis Cartilage 2015; 23:351-62. [PMID: 25450846 PMCID: PMC4339504 DOI: 10.1016/j.joca.2014.11.004] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 10/02/2014] [Accepted: 11/01/2014] [Indexed: 02/02/2023]
Abstract
Clinical efforts to repair damaged articular cartilage (AC) currently face major obstacles due to limited intrinsic repair capacity of the tissue and unsuccessful biological interventions. This highlights a need for better therapeutic strategies. This review summarizes the recent advances in the field of cell-based AC repair. In both animals and humans, AC defects that penetrate into the subchondral bone marrow are mainly filled with fibrocartilaginous tissue through the differentiation of bone marrow mesenchymal stem cells (MSCs), followed by degeneration of repaired cartilage and osteoarthritis (OA). Cell therapy and tissue engineering techniques using culture-expanded chondrocytes, bone marrow MSCs, or pluripotent stem cells with chondroinductive growth factors may generate cartilaginous tissue in AC defects but do not form hyaline cartilage-based articular surface because repair cells often lose chondrogenic activity or result in chondrocyte hypertrophy. The new evidence that AC and synovium develop from the same pool of precursors with similar gene profiles and that synovium-derived chondrocytes have stable chondrogenic activity has promoted use of synovium as a new cell source for AC repair. The recent finding that NFAT1 and NFAT2 transcription factors (TFs) inhibit chondrocyte hypertrophy and maintain metabolic balance in AC is a significant advance in the field of AC repair. The use of synovial MSCs and discovery of upstream transcriptional regulators that help maintain the AC phenotype have opened new avenues to improve the outcome of AC regeneration.
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Affiliation(s)
| | - Jinxi Wang
- Corresponding Author: Jinxi Wang, Address: University of Kansas Medical Center, Department of Orthopedic Surgery, 3901 Rainbow Blvd., Mail Stop 3017, Kansas City, KS 66160, USA, Phone: +1 913-588-0870, Fax: +1 913-945-7773,
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28
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Boland BS, Widjaja CE, Banno A, Zhang B, Kim SH, Stoven S, Peterson MR, Jones MC, Su HI, Crowe SE, Bui JD, Ho SB, Okugawa Y, Goel A, Marietta EV, Khosroheidari M, Jepsen K, Aramburu J, López-Rodríguez C, Sandborn WJ, Murray JA, Harismendy O, Chang JT. Immunodeficiency and autoimmune enterocolopathy linked to NFAT5 haploinsufficiency. THE JOURNAL OF IMMUNOLOGY 2015; 194:2551-60. [PMID: 25667416 DOI: 10.4049/jimmunol.1401463] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The link between autoimmune diseases and primary immunodeficiency syndromes has been increasingly appreciated. Immunologic evaluation of a young man with autoimmune enterocolopathy and unexplained infections revealed evidence of immunodeficiency, including IgG subclass deficiency, impaired Ag-induced lymphocyte proliferation, reduced cytokine production by CD8(+) T lymphocytes, and decreased numbers of NK cells. Genetic evaluation identified haploinsufficiency of NFAT5, a transcription factor regulating immune cell function and cellular adaptation to hyperosmotic stress, as a possible cause of this syndrome. Inhibition or deletion of NFAT5 in normal human and murine cells recapitulated several of the immune deficits identified in the patient. These results provide evidence of a primary immunodeficiency disorder associated with organ-specific autoimmunity linked to NFAT5 deficiency.
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Affiliation(s)
- Brigid S Boland
- Department of Medicine, University of California San Diego, La Jolla, CA 92093; Inflammatory Bowel Disease Center, University of California San Diego, La Jolla, CA 92093
| | | | - Asoka Banno
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Bing Zhang
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Stephanie H Kim
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | | | - Michael R Peterson
- Western Washington Pathology and Multicare Health System, Tacoma, WA 98405
| | - Marilyn C Jones
- Department of Pediatrics and Rady Children's Hospital, University of California San Diego, La Jolla, CA 92093
| | - H Irene Su
- Department of Reproductive Medicine, University of California San Diego, La Jolla, CA 92093
| | - Sheila E Crowe
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Jack D Bui
- Department of Pathology, University of California San Diego, La Jolla, CA 92093
| | - Samuel B Ho
- Department of Pathology, University of California San Diego, La Jolla, CA 92093
| | - Yoshinaga Okugawa
- Center for Gastrointestinal Research, Center for Epigenetics, Cancer Prevention and Cancer Genomics, Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246; Charles A. Sammons Cancer Center, Baylor University Medical Center, Dallas, TX 75246
| | - Ajay Goel
- Center for Gastrointestinal Research, Center for Epigenetics, Cancer Prevention and Cancer Genomics, Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246; Charles A. Sammons Cancer Center, Baylor University Medical Center, Dallas, TX 75246
| | | | - Mahdieh Khosroheidari
- Institute of Genomic Medicine, University of California San Diego, La Jolla, CA 92093
| | - Kristen Jepsen
- Institute of Genomic Medicine, University of California San Diego, La Jolla, CA 92093
| | - Jose Aramburu
- Immunology Unit, Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona 08003 Spain; and
| | - Cristina López-Rodríguez
- Immunology Unit, Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona 08003 Spain; and
| | - William J Sandborn
- Department of Medicine, University of California San Diego, La Jolla, CA 92093; Inflammatory Bowel Disease Center, University of California San Diego, La Jolla, CA 92093
| | | | - Olivier Harismendy
- Department of Medicine, University of California San Diego, La Jolla, CA 92093; Moores Cancer Center, University of California San Diego, La Jolla, CA 92093
| | - John T Chang
- Department of Medicine, University of California San Diego, La Jolla, CA 92093; Inflammatory Bowel Disease Center, University of California San Diego, La Jolla, CA 92093;
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Extracellular osmolarity regulates matrix homeostasis in the intervertebral disc and articular cartilage: evolving role of TonEBP. Matrix Biol 2014; 40:10-6. [PMID: 25172826 PMCID: PMC4390124 DOI: 10.1016/j.matbio.2014.08.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/18/2014] [Accepted: 08/19/2014] [Indexed: 12/20/2022]
Abstract
Degeneration of the intervertebral disc is characterized by changes in proteoglycan status, loss of bound water molecules, decreased tissue osmotic pressure and a resulting mechanical failure of the disc. A similar spectrum of changes is evident in osteoarthritic articular cartilage. When healthy, resident cells in these skeletal tissues respond to applied mechanical loads by regulating their own osmotic state and the hydration of the extracellular matrix. The transcription factor Tonicity-Responsive Enhancer Binding Protein (TonEBP or NFAT5) is known to mediate the osmoadaptive response in these and other tissues. While the molecular basis of how osmotic loading controls matrix homeostasis is not completely understood, TonEBP regulates the expression of aggrecan and β1,3-glucoronosyltransferase in nucleus pulposus cells, in addition to targets that allow for survival under hypertonic stress. Moreover, in chondrocytes, TonEBP controls expression of several collagen subtypes and Sox9, a master regulator of aggrecan and collagen II expression. Thus, TonEBP-mediated regulation of the matrix composition allows disc cells and chondrocytes to modify the extracellular osmotic state itself. On the other hand, TonEBP in immune cells induces expression of TNF-α, IL-6 and MCP-1, pro-inflammatory molecules closely linked to matrix catabolism and pathogenesis of both disc degeneration and osteoarthritis, warranting investigations of this aspect of TonEBP function in skeletal cells. In summary, the TonEBP system, through its effects on extracellular matrix and osmoregulatory genes can be viewed primarily as a protective or homeostatic response to physiological loading.
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Epigenetic control of cytokine gene expression: regulation of the TNF/LT locus and T helper cell differentiation. Adv Immunol 2013; 118:37-128. [PMID: 23683942 DOI: 10.1016/b978-0-12-407708-9.00002-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Epigenetics encompasses transient and heritable modifications to DNA and nucleosomes in the native chromatin context. For example, enzymatic addition of chemical moieties to the N-terminal "tails" of histones, particularly acetylation and methylation of lysine residues in the histone tails of H3 and H4, plays a key role in regulation of gene transcription. The modified histones, which are physically associated with gene regulatory regions that typically occur within conserved noncoding sequences, play a functional role in active, poised, or repressed gene transcription. The "histone code" defined by these modifications, along with the chromatin-binding acetylases, deacetylases, methylases, demethylases, and other enzymes that direct modifications resulting in specific patterns of histone modification, shows considerable evolutionary conservation from yeast to humans. Direct modifications at the DNA level, such as cytosine methylation at CpG motifs that represses promoter activity, are another highly conserved epigenetic mechanism of gene regulation. Furthermore, epigenetic modifications at the nucleosome or DNA level can also be coupled with higher-order intra- or interchromosomal interactions that influence the location of regulatory elements and that can place them in an environment of specific nucleoprotein complexes associated with transcription. In the mammalian immune system, epigenetic gene regulation is a crucial mechanism for a range of physiological processes, including the innate host immune response to pathogens and T cell differentiation driven by specific patterns of cytokine gene expression. Here, we will review current findings regarding epigenetic regulation of cytokine genes important in innate and/or adaptive immune responses, with a special focus upon the tumor necrosis factor/lymphotoxin locus and cytokine-driven CD4+ T cell differentiation into the Th1, Th2, and Th17 lineages.
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31
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Cheung CY, Ko BC. NFAT5 in cellular adaptation to hypertonic stress - regulations and functional significance. J Mol Signal 2013; 8:5. [PMID: 23618372 PMCID: PMC3655004 DOI: 10.1186/1750-2187-8-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/11/2013] [Indexed: 12/22/2022] Open
Abstract
The Nuclear Factor of Activated T Cells-5 (NFAT5), also known as OREBP or TonEBP, is a member of the nuclear factors of the activated T cells family of transcription factors. It is also the only known tonicity-regulated transcription factor in mammals. NFAT5 was initially known for its role in the hypertonic kidney inner medulla for orchestrating a genetic program to restore the cellular homeostasis. Emerging evidence, however, suggests that NFAT5 might play a more diverse functional role, including a pivotal role in blood pressure regulation and the development of autoimmune diseases. Despite the growing significance of NFAT5 in physiology and diseases, our understanding of how its activity is regulated remains very limited. Furthermore, how changes in tonicities are converted into functional outputs via NFAT5 remains elusive. Therefore, this review aims to summarize our current knowledge on the functional roles of NFAT5 in osmotic stress adaptation and the signaling pathways that regulate its activity.
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Affiliation(s)
- Chris Yk Cheung
- Department of Anatomical and Cellular Pathology, and The State Key Laboratory in Oncology in South China, The Chinese University of Hong Kong, The Prince of Wales Hospital, Rm 38019, Clinical Sciences Building, Shatin, Hong Kong, China.
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Wang H, Dong D, Tang S, Chen X, Gao Q. PPE38 of Mycobacterium marinum triggers the cross-talk of multiple pathways involved in the host response, as revealed by subcellular quantitative proteomics. J Proteome Res 2013; 12:2055-66. [PMID: 23514422 PMCID: PMC3646403 DOI: 10.1021/pr301017e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
The
PE/PPE family of proteins which are in high abundance in pathogenic
species such as Mycobacterium tuberculosis and M. marinum, play the critical
role in generating antigenic variation and evasion of host immune
responses. However, little is known about their functional roles in
mycobacterial pathogenesis. Previously, we found that PPE38 is associated
with the virulence of mycobacteria, presumably by modulating the host
immune response. To clarify the link between PPE38 and host response,
we employed a subcellular, amino acid-coded mass tagging (AACT)/SILAC-based
quantitative proteomic approach to determine the proteome changes
during host response to M. marinum PPE38.
As a result, 291 or 290 proteins were found respectively to be up-
or down-regulated in the nucleus. Meanwhile, 576 upregulated and 272
downregulated proteins were respectively detected in the cytosol.
The data of quantitative proteomic changes and concurrent biological
validations revealed that M. marinum PPE38 could trigger extensive inflammatory responses in macrophages,
probably through interacting with toll-like receptor 2 (TLR2). We
also found that PPE38 may arrest MHC-1 processing and presentation
in infected macrophages. Using bioinformatics tools to analyze global
changes in the host proteome, we obtained a PPE38-respondor network involved in various transcriptional factors (TFs) and TF-associated
proteins. The results of our systems investigation now indicate that there is cross-talk involving a broad range of diverse biological pathways/processes that coordinate the host response to M. marinum PPE38.
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Affiliation(s)
- Hui Wang
- Key Laboratory of Medical Molecular Virology, Institute of Biomedical Sciences and Institute of Medical Microbiology, Shanghai Medical College, Fudan University, Shanghai 200032, China
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Hao S, Bellner L, Ferreri NR. NKCC2A and NFAT5 regulate renal TNF production induced by hypertonic NaCl intake. Am J Physiol Renal Physiol 2012; 304:F533-42. [PMID: 23269645 DOI: 10.1152/ajprenal.00243.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Pathways that contribute to TNF production by the kidney are not well defined. Mice given 1% NaCl in the drinking water for 3 days exhibited a 2.5-fold increase in urinary, but not plasma, TNF levels compared with mice given tap water. Since furosemide attenuated the increase in TNF levels, we hypothesized that hypertonic NaCl intake increases renal TNF production by a pathway involving the Na(+)-K(+)-2Cl(-) cotransporter (NKCC2). A 2.5-fold increase in NKCC2A mRNA accumulation was observed in medullary thick ascending limb (mTAL) tubules from mice given 1% NaCl; a concomitant 2-fold increase in nuclear factor of activated T cells 5 (NFAT5) mRNA and protein expression was observed in the outer medulla. Urinary TNF levels were reduced in mice given 1% NaCl after an intrarenal injection of a lentivirus construct designed to specifically knockdown NKCC2A (EGFP-N2A-ex4); plasma levels of TNF did not change after injection of EGFP-N2A-ex4. Intrarenal injection of EGFP-N2A-ex4 also inhibited the increase of NFAT5 mRNA abundance in the outer medulla of mice given 1% NaCl. TNF production by primary cultures of mTAL cells increased approximately sixfold in response to an increase in osmolality to 400 mosmol/kgH2O produced with NaCl and was inhibited in cells transiently transfected with a dnNFAT5 construct. Transduction of cells with EGFP-N2A-ex4 also prevented increases in TNF mRNA and protein production in response to high NaCl concentration and reduced transcriptional activity of a NFAT5 promoter construct. Since NKCC2A expression is restricted to the TAL, NKCC2A-dependent activation of NFAT5 is part of a pathway by which the TAL produces TNF in response to hypertonic NaCl intake.
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Affiliation(s)
- Shoujin Hao
- Dept. of Pharmacology, New York Medical College, Valhalla, NY 10595, USA
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Arroyo JA, Garcia-Jones P, Graham A, Teng CC, Battaglia FC, Galan HL. Placental TonEBP/NFAT5 osmolyte regulation in an ovine model of intrauterine growth restriction. Biol Reprod 2012; 86:94. [PMID: 22190709 DOI: 10.1095/biolreprod.111.094797] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
TonEBP/NFAT5 (the tonicity-responsive enhancer binding protein/nuclear factor of activated T cells) modulates cellular response to osmotic changes by accumulating inositol and sorbitol inside the cells. Our objective was to assess placental osmolytes, TonEBP/NFAT5 RNA and protein expression, and signaling molecules across gestation between control and intrauterine growth restriction (IUGR) ovine pregnancies. Pregnant sheep were placed in hyperthermic conditions to induce IUGR. Placental tissues were collected at 55, 95, and 130 days gestational age (dGA) to measure inositol, sorbitol, TonEBP/NFAT5 (NFAT5), sodium-dependent myo-inositol transporter (SMIT; official symbol SLC5A3), aldose reductase (AR), and NADPH (official symbol DE-CR1). Placental weight was reduced in IUGR compared to controls at 95 and 130 dGA. Osmolyte concentrations were similar between control and IUGR placentas, but both groups demonstrated a significant decrease in inositol concentration and an increase in sorbitol concentration with advancing gestation. Cytosolic NFAT5 protein decreased significantly from 55 to 95 dGA in both groups, and nuclear NFAT5 protein increased only at 130 dGA in the IUGR group, but no differences were seen between groups for either cytosolic or nuclear NFAT5 protein concentrations. DE-CR1 concentrations were similar between groups and increased significantly with advancing gestational age. AR was lowest at 55dGA, and SLC5A3 increased with advancing gestational age. We conclude that both placental osmolytes inositol and sorbitol (and their corresponding proteins SLC5A3 and AR) change with gestational age and are regulated, at least in part, by NFAT5 and DE-CR1 (NADPH). The inverse relationship between each osmolyte across gestation (e.g., inositol higher in early gestation and sorbitol higher in late gestation) may reflect nutritional needs that change across gestation.
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Affiliation(s)
- Juan A Arroyo
- Department of Obstetrics and Gynecology, University of Colorado Denver and Health Sciences Center, Aurora, Colorado, USA.
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Halterman JA, Kwon HM, Wamhoff BR. Tonicity-independent regulation of the osmosensitive transcription factor TonEBP (NFAT5). Am J Physiol Cell Physiol 2011; 302:C1-8. [PMID: 21998140 DOI: 10.1152/ajpcell.00327.2011] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Tonicity-responsive enhancer binding protein (TonEBP/nuclear factor of activated T-cells 5 [NFAT5]) is a Rel homology transcription factor classically known for its osmosensitive role in regulating cellular homeostasis during states of hypo- and hypertonic stress. A recently growing body of research indicates that TonEBP is not solely regulated by tonicity, but that it can be stimulated by various tonicity-independent mechanisms in both hypertonic and isotonic tissues. Physiological and pathophysiological stimuli such as cytokines, growth factors, receptor and integrin activation, contractile agonists, ions, and reactive oxygen species have been implicated in the positive regulation of TonEBP expression and activity in diverse cell types. These new data demonstrate that tonicity-independent stimulation of TonEBP is critical for tissue-specific functions like enhanced cell survival, migration, proliferation, vascular remodeling, carcinoma invasion, and angiogenesis. Continuing research will provide a better understanding as to how these and other alternative TonEBP stimuli regulate gene expression in both health and disease.
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Affiliation(s)
- Julia A Halterman
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
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Falvo JV, Ranjbar S, Jasenosky LD, Goldfeld AE. Arc of a vicious circle: pathways activated by Mycobacterium tuberculosis that target the HIV-1 long terminal repeat. Am J Respir Cell Mol Biol 2011; 45:1116-24. [PMID: 21852682 DOI: 10.1165/rcmb.2011-0186tr] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In this review, we examine how a subset of signal transduction cascades initiated by Mycobacterium tuberculosis (Mtb) infection modulates transcription mediated by the human immunodeficiency virus type 1 long terminal repeat (HIV-1 LTR). We describe two distinct phases of signaling that target transcription factors known to bind the HIV-1 LTR, and thus drive viral transcription and replication, in cells of the Mtb-infected host. First, Mtb-derived molecules, including cell wall components and DNA, interact with a number of host pattern recognition receptors. Second, cytokines and chemokines secreted in response to Mtb infection initiate signal transduction cascades through their cognate receptors. Given the variation in cell wall components among distinct clinical Mtb strains, the initial pattern recognition receptor interaction leading to direct LTR activation and differential cytokine and chemokine production is likely to be an important aspect of Mtb strain-specific regulation of HIV-1 transcription and replication. Improved understanding of these molecular mechanisms in the context of bacterial and host genetics should provide key insights into the accelerated viral replication and disease progression characteristic of HIV/TB coinfection.
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Affiliation(s)
- James V Falvo
- Immune Disease Institute and Program in Cellular and Molecular Medicine, Children’s Hospital Boston, MA, USA.
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Hypertonicity-enhanced TNF-α release from activated human monocytic THP-1 cells requires ERK activation. Biochim Biophys Acta Gen Subj 2011; 1810:475-84. [PMID: 21256190 DOI: 10.1016/j.bbagen.2011.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 12/23/2010] [Accepted: 01/14/2011] [Indexed: 01/10/2023]
Abstract
BACKGROUND Hypertonic stress enhances tumor necrosis factor (TNF)-α expression in activated monocytes. However, the underlying mechanism is unknown. The produced TNF-α is primarily cleaved and released by TNF-α-converting enzyme (TACE), and the surface expression of TACE is down-regulated by endocytosis. As hypertonicity inhibits endocytosis, we evaluated the mechanism of hypertonicity-induced TNF-α release from activated human monocytic THP-1 cells. METHODS THP-1 cells were stimulated with lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA) in the presence or absence of hypertonic agents (150 mM sucrose or 150-300 mM NaCl). The amount of TNF-α mRNA and protein, surface expression of TACE and activation of signaling pathways (mitogen-activated protein kinase, Akt and NF-κB) were assayed. RESULTS Hypertonic sucrose and NaCl significantly enhanced TNF-α release from THP-1 cells upon LPS or PMA stimulation. Hypertonic sucrose and other endocytosis inhibitors increased surface expression of TACE, but their effects on TNF-α release were inconsistent. This enhancement effect by hypertonicity was not attenuated by inhibition of TACE or IκB kinase, but it was blocked by cycloheximide and a MAP/ERK kinase inhibitor. The LPS- or PMA-induced TNF-α mRNA expression was not increased; rather, it was inhibited by hypertonicity. ERK1/2 was re-activated after sucrose treatment in LPS-stimulated THP-1 cells. CONCLUSIONS Hypertonicity-enhanced TNF-α protein synthesis from LPS- or PMA-activated THP-1 cells requires ERK activation and may proceed without TACE. GENERAL SIGNIFICANCE A vast amount of TNF-α production was regulated by a crucial post-transcriptional manner in activated human monocytic leukemia cells, and it may possibly be contributed to the cachexia condition.
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Hao S, Zhao H, Darzynkiewicz Z, Battula S, Ferreri NR. Differential regulation of NFAT5 by NKCC2 isoforms in medullary thick ascending limb (mTAL) cells. Am J Physiol Renal Physiol 2011; 300:F966-75. [PMID: 21228109 DOI: 10.1152/ajprenal.00408.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The effects of Na(+)-K(+)-2Cl(-) cotransporter type 2 (NKCC2) isoforms on the regulation of nuclear factor of activated T cells isoform 5 (NFAT5) were determined in mouse medullary thick ascending limb (mTAL) cells exposed to high NaCl concentration. Primary cultures of mTAL cells and freshly isolated mTAL tubules, both derived from the outer medulla (outer stripe>inner stripe), express NKCC2 isoforms A and F. The relative expression of NKCC2A mRNA was approximately twofold greater than NKCC2F in these preparations. The abundance of NKCC2A mRNA, but not NKCC2F mRNA, increased approximately twofold when mTAL cells were exposed for 2 h to a change in osmolality from 300 to 500 mosmol/kgH₂O, produced with NaCl. Total NKCC2 protein expression also increased. Moreover, a 2.5-fold increase in NFAT5 mRNA accumulation was observed after cells were exposed to 500 mosmol/kgH₂O for 4 h. Laser-scanning cytometry detected a twofold increase in endogenous NFAT5 protein expression in response to high NaCl concentration. Pretreatment with the loop diuretic bumetanide dramatically reduced transcriptional activity of the NFAT5-specific reporter construct TonE-Luc in mTAL cells exposed to high NaCl. Transient transfection of mTAL cells with shRNA vectors targeting NKCC2A prevented increases in NFAT5 mRNA abundance and protein expression and inhibited NFAT5 transcriptional activity in response to hypertonic stress. Silencing of NKCC2F mRNA did not affect NFAT5 mRNA accumulation but partially inhibited NFAT5 transcriptional activity. These findings suggest that NKCC2A and NKCC2F exhibit differential effects on NFAT5 expression and transcriptional activity in response to hypertonicity produced by high NaCl concentration.
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Affiliation(s)
- Shoujin Hao
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
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Roth I, Leroy V, Kwon HM, Martin PY, Féraille E, Hasler U. Osmoprotective transcription factor NFAT5/TonEBP modulates nuclear factor-kappaB activity. Mol Biol Cell 2010; 21:3459-74. [PMID: 20685965 PMCID: PMC2947481 DOI: 10.1091/mbc.e10-02-0133] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Tonicity responsive binding protein (TonEBP) is a transcription factor that plays a key role in osmoprotection. Here, we demonstrate enhanced activity of prosurvival NF-κB—at the onset of hypertonic challenge that depends on p38 kinase—and Akt-dependent formation of p65-TonEBP complexes that bind to elements of NF-κB-responsive genes. Tonicity-responsive binding-protein (TonEBP or NFAT5) is a widely expressed transcription factor whose activity is regulated by extracellular tonicity. TonEBP plays a key role in osmoprotection by binding to osmotic response element/TonE elements of genes that counteract the deleterious effects of cell shrinkage. Here, we show that in addition to this “classical” stimulation, TonEBP protects cells against hypertonicity by enhancing nuclear factor-κB (NF-κB) activity. We show that hypertonicity enhances NF-κB stimulation by lipopolysaccharide but not tumor necrosis factor-α, and we demonstrate overlapping protein kinase B (Akt)-dependent signal transduction pathways elicited by hypertonicity and transforming growth factor-α. Activation of p38 kinase by hypertonicity and downstream activation of Akt play key roles in TonEBP activity, IκBα degradation, and p65 nuclear translocation. TonEBP affects neither of these latter events and is itself insensitive to NF-κB signaling. Rather, we reveal a tonicity-dependent interaction between TonEBP and p65 and show that NF-κB activity is considerably enhanced after binding of NF-κB-TonEBP complexes to κB elements of NF-κB–responsive genes. We demonstrate the key roles of TonEBP and Akt in renal collecting duct epithelial cells and in macrophages. These findings reveal a novel role for TonEBP and Akt in NF-κB activation on the onset of hypertonic challenge.
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Affiliation(s)
- Isabelle Roth
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland
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Kojima R, Taniguchi H, Tsuzuki A, Nakamura K, Sakakura Y, Ito M. Hypertonicity-induced expression of monocyte chemoattractant protein-1 through a novel cis-acting element and MAPK signaling pathways. THE JOURNAL OF IMMUNOLOGY 2010; 184:5253-62. [PMID: 20368270 DOI: 10.4049/jimmunol.0901298] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
MCP1 is upregulated by various stimuli, including LPS, high glucose, and hyperosmolality. However, the molecular mechanisms of transcriptional regulation of the MCP1 gene under hyperosmolar conditions are poorly understood. Treatment of NRK52E cells with NaCl or mannitol resulted in significant elevation of MCP1 mRNA and protein in a time- and dose-dependent manner. Treatment with a p38MAPK inhibitor (SB203580), an ERK inhibitor (PD98059), or an MEK inhibitor (U0126), suppressed the increase in MCP1 expression caused by hypertonic NaCl, whereas a JNK inhibitor (SP600125) and an AP1 inhibitor (curcumin) failed to attenuate MCP1 mRNA expression by NaCl. In the 5'-flanking region of the MCP1 gene, there is a sequence motif similar to the consensus TonE/ORE as well as the consensus C/E binding protein (BP), NF-kappaB, and AP1/Sp1 sites. Luciferase activity in cells transfected with reporter constructs containing a putative TonE/ORE element (MCP1-TonE/ORE) enhanced reporter gene expression under hypertonic stress. Results of electrophoretic gel mobility shift assay showed a slow migration of the MCP1-TonE/ORE probe, representing the binding of TonEBP/OREBP/NFAT5 to this enhancer element. These results indicate that the 5'-flanking region of MCP1 contains a hypertonicity-sensitive cis-acting element, MCP1-TonE/ORE, as a novel element in the MCP1 gene. Furthermore, p38MAPK and MEK-ERK pathways appear to be, at least in part, involved in hypertonic stress-mediated regulation of MCP1 expression through the MCP1-TonE/ORE.
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Affiliation(s)
- Ryoji Kojima
- Laboratory of Analytical Pharmacology, Faculty of Pharmacy, Meijo University, Nagoya 468-8503, Japan.
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Falvo JV, Tsytsykova AV, Goldfeld AE. Transcriptional control of the TNF gene. ACTA ACUST UNITED AC 2010; 11:27-60. [PMID: 20173386 DOI: 10.1159/000289196] [Citation(s) in RCA: 187] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cytokine TNF is a critical mediator of immune and inflammatory responses. The TNF gene is an immediate early gene, rapidly transcribed in a variety of cell types following exposure to a broad range of pathogens and signals of inflammation and stress. Regulation of TNF gene expression at the transcriptional level is cell type- and stimulus-specific, involving the recruitment of distinct sets of transcription factors to a compact and modular promoter region. In this review, we describe our current understanding of the mechanisms through which TNF transcription is specifically activated by a variety of extracellular stimuli in multiple cell types, including T cells, B cells, macrophages, mast cells, dendritic cells, and fibroblasts. We discuss the role of nuclear factor of activated T cells and other transcription factors and coactivators in enhanceosome formation, as well as the contradictory evidence for a role for nuclear factor kappaB as a classical activator of the TNF gene. We describe the impact of evolutionarily conserved cis-regulatory DNA motifs in the TNF locus upon TNF gene transcription, in contrast to the neutral effect of single nucleotide polymorphisms. We also assess the regulatory role of chromatin organization, epigenetic modifications, and long-range chromosomal interactions at the TNF locus.
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Affiliation(s)
- James V Falvo
- Immune Disease Institute and Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
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Chen S, Grigsby CL, Law CS, Ni X, Nekrep N, Olsen K, Humphreys MH, Gardner DG. Tonicity-dependent induction of Sgk1 expression has a potential role in dehydration-induced natriuresis in rodents. J Clin Invest 2009; 119:1647-58. [PMID: 19436108 DOI: 10.1172/jci35314] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Accepted: 03/18/2009] [Indexed: 01/06/2023] Open
Abstract
In various mammalian species, including humans, water restriction leads to an acute increase in urinary sodium excretion. This process, known as dehydration natriuresis, helps prevent further accentuation of hypernatremia and the accompanying rise in extracellular tonicity. Serum- and glucocorticoid-inducible kinase (Sgk1), which is expressed in the renal medulla, is regulated by extracellular tonicity. However, the mechanism of its regulation and the physiological role of hypertonicity-induced SGK1 gene expression remain unclear. Here, we identified a tonicity-responsive enhancer (TonE) upstream of the rat Sgk1 transcriptional start site. The transcription factor NFAT5 associated with TonE in a tonicity-dependent fashion in cultured rat renal medullary cells, and selective blockade of NFAT5 activity resulted in suppression of the osmotic induction of the Sgk1 promoter. In vivo, water restriction of rats or mice led to increased urine osmolality, increased Sgk1 expression, increased expression of the type A natriuretic peptide receptor (NPR-A), and dehydration natriuresis. In cultured rat renal medullary cells, siRNA-mediated Sgk1 knockdown blocked the osmotic induction of natriuretic peptide receptor 1 (Npr1) gene expression. Furthermore, Npr1-/- mice were resistant to dehydration natriuresis, which suggests that Sgk1-dependent activation of the NPR-A pathway may contribute to this response. Collectively, these findings define a specific mechanistic pathway for the osmotic regulation of Sgk1 gene expression and suggest that Sgk1 may play an important role in promoting the physiological response of the kidney to elevations in extracellular tonicity.
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Affiliation(s)
- Songcang Chen
- Diabetes Center, UCSF, San Francisco, California 94143-0540, USA
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Hao S, Zhao H, Darzynkiewicz Z, Battula S, Ferreri NR. Expression and function of NFAT5 in medullary thick ascending limb (mTAL) cells. Am J Physiol Renal Physiol 2009; 296:F1494-503. [PMID: 19369291 DOI: 10.1152/ajprenal.90436.2008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The contribution of nuclear factor of activated T cells 5 (NFAT5) to the regulation of tumor necrosis factor-alpha (TNF) production in medullary thick ascending limb (mTAL) cells is unclear. RT-PCR analysis was performed on primary cultures of mouse mTAL cells and freshly isolated mTAL tubules to determine which NFAT isoforms are present in this nephron segment. Primer pairs were designed, based on published sequences for mouse NFAT1-5, to produce fragments of approximately 200 bp. Analysis of PCR products by gel electrophoresis and subsequent DNA sequencing indicated that cells and tubules contained mRNA for all five NFAT isoforms. The relative expression of NFAT isoforms was then determined using quantitative real-time RT-PCR. The data indicate that NFAT isoforms 5 >/= 1 are the predominant isoforms present in mTAL cells and tubules. Western blot analysis demonstrated constitutive expression of NFAT5 in nuclear extracts from mTAL tubules and primary culture cells; expression in mTAL cells also was detected by immunofluorescence. Expression of NFAT5 was increased in mTAL cells transiently transfected with an NFAT5 overexpression vector (pcDNA3.1-NFAT5), resulting in increased basal and calcium-sensing receptor (CaR)-mediated TNF production. Transient transfection of mTAL cells with a small hairpin RNA vector that targeted exon 8 of NFAT5 (U6-N5 ex8) significantly inhibited TNF promoter activity. Transient transfection with U6-N5 ex8 also reduced nuclear expression of NFAT5, TNF mRNA accumulation, and attenuated CaR-mediated activation of Cl(-) entry into polarized mTAL cells. Collectively, these data suggest that activation of NFAT5 is part of a TNF-dependent pathway that inhibits apical Cl(-) influx in the mTAL after activation of CaR.
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Affiliation(s)
- Shoujin Hao
- Department of Pharmacology, New York Medical College, Valhalla, NY 10595, USA
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Kino T, Takatori H, Manoli I, Wang Y, Tiulpakov A, Blackman MR, Su YA, Chrousos GP, DeCherney AH, Segars JH. Brx mediates the response of lymphocytes to osmotic stress through the activation of NFAT5. Sci Signal 2009; 2:ra5. [PMID: 19211510 DOI: 10.1126/scisignal.2000081] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Extracellular hyperosmolarity, or osmotic stress, generally caused by differences in salt and macromolecule concentrations across the plasma membrane, occurs in lymphoid organs and at inflammatory sites. The response of immune cells to osmotic stress is regulated by nuclear factor of activated T cells 5 (NFAT5), a transcription factor that induces the expression of hyperosmolarity-responsive genes and stimulates cytokine production. We report that the guanine nucleotide exchange factor (GEF) Brx [also known as protein kinase A-anchoring protein 13 (AKAP13)] is essential for the expression of nfat5 in response to osmotic stress, thus transmitting the extracellular hyperosmolarity signal and enabling differentiation of splenic B cells and production of immunoglobulin. This process required the activity of p38 mitogen-activated protein kinase (MAPK) and NFAT5 and involved a physical interaction between Brx and c-Jun N-terminal kinase (JNK)-interacting protein 4 (JIP4), a scaffold molecule specific to activation of the p38 MAPK cascade. Our results indicate that Brx integrates the responses of immune cells to osmotic stress and inflammation by elevating intracellular osmolarity and stimulating the production of cytokines.
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Affiliation(s)
- Tomoshige Kino
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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Liu MG, Li H, Xu X, Barnstable CJ, Zhang SSM. Comparison of gene expression during in vivo and in vitro postnatal retina development. J Ocul Biol Dis Infor 2008; 1:59-72. [PMID: 20072636 PMCID: PMC2802513 DOI: 10.1007/s12177-008-9009-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 06/05/2008] [Indexed: 10/31/2022] Open
Abstract
UNLABELLED Retina explants are widely used as a model of neural development. To define the molecular basis of differences between the development of retina in vivo and in vitro during the early postnatal period, we carried out a series of microarray comparisons using mouse retinas. About 75% of 8,880 expressed genes from retina explants kept the same expression volume and pattern as the retina in vivo. Fewer than 6% of the total gene population was changed at two consecutive time points, and only about 1% genes showed more than a threefold change at any time point studied. Functional Gene Ontology (GO) mapping for both changed and unchanged genes showed similar distribution patterns, except that more genes were changed in the GO clusters of response to stimuli and carbohydrate metabolism. Three distinct expression patterns of genes preferentially expressed in rod photoreceptors were observed in the retina explants. Some genes showed a lag in increased expression, some showed no change, and some continued to have a reduced level of expression. An early downregulation of cyclin D1 in the explanted retina might explain the reduction in numbers of precursors in explanted retina and suggests that external factors are required for maintenance of cyclin D1. The global view of gene profiles presented in this study will help define the molecular changes in retina explants over time and will provide criteria to define future changes that improve this model system. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s12177-008-9009-z) contains supplementary material, which is available to authorized users.
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Garrett S, Dietzmann-Maurer K, Song L, Sullivan KE. Polarization of primary human monocytes by IFN-gamma induces chromatin changes and recruits RNA Pol II to the TNF-alpha promoter. THE JOURNAL OF IMMUNOLOGY 2008; 180:5257-66. [PMID: 18390706 DOI: 10.4049/jimmunol.180.8.5257] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Monocyte polarization by IFN-gamma or IL-4 drives a complex series of cellular responses leading to increased intracellular killing (IFN-gamma) or enhanced healing (IL-4) among other functional responses. We studied the effect of IL-4 and IFN-gamma polarization on histone modifications at the TNF-alpha locus in human primary monocytes. IFN-gamma polarization markedly increased the expression of TNF-alpha, whereas IL-4 treatment decreased the expression. We found that IFN-gamma alone increased histone H4 acetylation at the TNF-alpha promoter. The effect of IFN-gamma on TNF-alpha expression was durable upon cytokine washout and even repolarization with IL-4. Concordantly, IFN-gamma-mediated H4 acetylation was also durable. IFN-gamma recruited activating transcription factor-2 via p38 to the TNF-alpha promoter, but inhibition of p38 had minimal effect on H4 acetylation. In a novel finding, we found that IFN-gamma recruited RNA Pol II to the human TNF-alpha promoter via ERK signaling, but did so without initiating transcription, leading to a poised condition. These studies provide an important perspective on monocyte polarization. Polarization by IFN-gamma has a durable effect on TNF-alpha expression, and histone acetylation may provide a mechanism for persistence of the effect.
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Affiliation(s)
- Stacey Garrett
- Division of Allergy Immunology, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Cho HJ, Jin SM, Youn HD, Huh K, Mook-Jung I. Disrupted intracellular calcium regulates BACE1 gene expression via nuclear factor of activated T cells 1 (NFAT 1) signaling. Aging Cell 2008; 7:137-47. [PMID: 18081741 DOI: 10.1111/j.1474-9726.2007.00360.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Beta-site APP-cleaving enzyme 1 (BACE1) expression is elevated in the brains of Alzheimer's disease (AD) patients and in aged-animal models. Because both AD and aging are associated with disrupted calcium homeostasis, we investigated the role of nuclear factor of activated T cells (NFAT) - a transcription factor regulated by the calcium- and calmodulin-dependent phosphatase calcineurin - in BACE1 expression. BACE1 expression was stimulated by a calcium ionophore in primary cortical cultures, and by SH-SY5Y neuroblastoma cells, which was both blocked by pretreatment with either cyclosporin A, an inhibitor of calcineurin, or ethyleneglycotetraacetic acid, a calcium chelator. Gel shift assays revealed direct binding of NFAT1 to specific DNA sequences within the BACE1 gene promoter region. Treatment with amyloid beta (Abeta), one of the major factors in AD pathogenesis, stimulated activation and nuclear translocation of NFAT1 following up-regulation of BACE1 expression. In addition, primary cortical cultures from Tg2576 mouse brains generated more Abeta by ionophore stimulation, which was reversed by cyclosporin A treatment. Furthermore, NFAT1 activation was observed in Tg2576 mouse brains. These results suggest that calcium ionophore- or Abeta-induced increases in intracellular calcium concentration stimulate BACE1 expression, resulting in accelerated Abeta generation, and that this process is mediated through the calcineurin-NFAT1 signaling pathway. This process may play a significant role in the pathogenesis of AD and aging.
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Affiliation(s)
- Hyun Jin Cho
- Department of Biochemistry and Cancer Research Institute, Seoul National University College of Medicine, Seoul, South Korea
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Morancho B, Minguillón J, Molkentin JD, López-Rodríguez C, Aramburu J. Analysis of the transcriptional activity of endogenous NFAT5 in primary cells using transgenic NFAT-luciferase reporter mice. BMC Mol Biol 2008; 9:13. [PMID: 18221508 PMCID: PMC2262899 DOI: 10.1186/1471-2199-9-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 01/25/2008] [Indexed: 12/13/2022] Open
Abstract
Background The transcription factor NFAT5/TonEBP regulates the response of mammalian cells to hypertonicity. However, little is known about the physiopathologic tonicity thresholds that trigger its transcriptional activity in primary cells. Wilkins et al. recently developed a transgenic mouse carrying a luciferase reporter (9xNFAT-Luc) driven by a cluster of NFAT sites, that was activated by calcineurin-dependent NFATc proteins. Since the NFAT site of this reporter was very similar to an optimal NFAT5 site, we tested whether this reporter could detect the activation of NFAT5 in transgenic cells. Results The 9xNFAT-Luc reporter was activated by hypertonicity in an NFAT5-dependent manner in different types of non-transformed transgenic cells: lymphocytes, macrophages and fibroblasts. Activation of this reporter by the phorbol ester PMA plus ionomycin was independent of NFAT5 and mediated by NFATc proteins. Transcriptional activation of NFAT5 in T lymphocytes was detected at hypertonic conditions of 360–380 mOsm/kg (isotonic conditions being 300 mOsm/kg) and strongly induced at 400 mOsm/kg. Such levels have been recorded in plasma in patients with osmoregulatory disorders and in mice deficient in aquaporins and vasopressin receptor. The hypertonicity threshold required to activate NFAT5 was higher in bone marrow-derived macrophages (430 mOsm/kg) and embryonic fibroblasts (480 mOsm/kg). Activation of the 9xNFAT-Luc reporter by hypertonicity in lymphocytes was insensitive to the ERK inhibitor PD98059, partially inhibited by the PI3-kinase inhibitor wortmannin (0.5 μM) and the PKA inhibitor H89, and substantially downregulated by p38 inhibitors (SB203580 and SB202190) and by inhibition of PI3-kinase-related kinases with 25 μM LY294002. Sensitivity of the reporter to FK506 varied among cell types and was greater in primary T cells than in fibroblasts and macrophages. Conclusion Our results indicate that NFAT5 is a sensitive responder to pathologic increases in extracellular tonicity in T lymphocytes. Activation of NFAT5 by hypertonicity in lymphocytes was mediated by a combination of signaling pathways that differed from those required in other cell types. We propose that the 9xNFAT-Luc transgenic mouse model might be useful to study the physiopathological regulation of both NFAT5 and NFATc factors in primary cells.
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Affiliation(s)
- Beatriz Morancho
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain.
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Irarrazabal CE, Williams CK, Ely MA, Birrer MJ, Garcia-Perez A, Burg MB, Ferraris JD. Activator protein-1 contributes to high NaCl-induced increase in tonicity-responsive enhancer/osmotic response element-binding protein transactivating activity. J Biol Chem 2007; 283:2554-63. [PMID: 18056707 DOI: 10.1074/jbc.m703490200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tonicity-responsive enhancer/osmotic response element-binding protein (TonEBP/OREBP) is a Rel protein that activates transcription of osmoprotective genes at high extracellular NaCl. Other Rel proteins NFAT1-4 and NF-kappaB complex with activator protein-1 (AP-1) to transactivate target genes through interaction at composite NFAT/NF-kappaB.AP-1 sites. TonEBP/OREBP target genes commonly have one or more conserved AP-1 binding sites near TonEBP/OREBP cognate elements (OREs). Also, TonEBP/OREBP and the AP-1 proteins c-Fos and c-Jun are all activated by high NaCl. We now find, using an ORE.AP-1 reporter from the target aldose reductase gene or the same reporter with a mutated AP-1 site, that upon stimulation by high extracellular NaCl, 1) the presence of a wild type, but not a mutated, AP-1 site contributes to TonEBP/OREBP-dependent transcription and 2) AP-1 dominant negative constructs inhibit TonEBP/OREBP-dependent transcription provided the AP-1 site is not mutated. Using supershifts and an ORE.AP-1 probe, we find c-Fos and c-Jun present in combination with TonEBP/OREBP. Also, c-Fos and c-Jun coimmunoprecipitate with TonEBP/OREBP, indicating physical association. Small interfering RNA knockdown of either c-Fos or c-Jun inhibits high NaCl-induced increase of mRNA abundance of the TonEBP/OREBP target genes AR and BGT1. Furthermore, a dominant negative AP-1 also reduces high NaCl-induced increase of TonEBP/OREBP transactivating activity. Inhibition of p38, which is known to stimulate TonEBP/OREBP transcriptional activity, reduces high NaCl-dependent transcription of an ORE.AP-1 reporter only if the AP-1 site is intact. Thus, AP-1 is part of the TonEBP/OREBP enhanceosome, and its role in high NaCl-induced activation of TonEBP/OREBP may require p38 activity.
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Affiliation(s)
- Carlos E Irarrazabal
- Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health/DHHS, 10 Center Drive, Bethesda, MD 20892, USA
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Abstract
Cells in the renal inner medulla are normally exposed to extraordinarily high levels of NaCl and urea. The osmotic stress causes numerous perturbations because of the hypertonic effect of high NaCl and the direct denaturation of cellular macromolecules by high urea. High NaCl and urea elevate reactive oxygen species, cause cytoskeletal rearrangement, inhibit DNA replication and transcription, inhibit translation, depolarize mitochondria, and damage DNA and proteins. Nevertheless, cells can accommodate by changes that include accumulation of organic osmolytes and increased expression of heat shock proteins. Failure to accommodate results in cell death by apoptosis. Although the adapted cells survive and function, many of the original perturbations persist, and even contribute to signaling the adaptive responses. This review addresses both the perturbing effects of high NaCl and urea and the adaptive responses. We speculate on the sensors of osmolality and document the multiple pathways that signal activation of the transcription factor TonEBP/OREBP, which directs many aspects of adaptation. The facts that numerous cellular functions are altered by hyperosmolality and remain so, even after adaptation, indicate that both the effects of hyperosmolality and adaptation to it involve profound alterations of the state of the cells.
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