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Jiang M, Salari A, Stock C, Nikolovska K, Boedtkjer E, Amiri M, Seidler UE. The electroneutral Na +-HCO 3- cotransporter NBCn1 (SLC4A7) modulates colonic enterocyte pH i, proliferation, and migration. Am J Physiol Cell Physiol 2024; 326:C1625-C1636. [PMID: 38646790 DOI: 10.1152/ajpcell.00079.2024] [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: 02/01/2024] [Revised: 04/05/2024] [Accepted: 04/06/2024] [Indexed: 04/23/2024]
Abstract
NBCn1 (SLC4A7) is one of the two major Na+-HCO3- cotransporters in the human colonic epithelium, expressed predominantly in the highly proliferating colonocytes at the cryptal base. Increased NBCn1 expression levels are reported in tumors, including colorectal cancer. The study explores its importance for maintenance of the intracellular pH (pHi), as well as the proliferative, adhesive, and migratory behavior of the self-differentiating Caco2BBe colonic tumor cell line. In the self-differentiating Caco2BBe cells, NBCn1 mRNA was highly expressed from the proliferative stage until full differentiation. The downregulation of NBCn1 expression by RNA interference affected proliferation and differentiation and decreased intracellular pH (pHi) of the cells in correlation with the degree of knockdown. In addition, a disturbed cell adhesion and reduced migratory speed were associated with NBCn1 knockdown. Murine colonic Nbcn1-/- enteroids also displayed reduced proliferative activity. In the migrating Caco2BBe cells, NBCn1 was found at the leading edge and in colocalization with the focal adhesion markers vinculin and paxillin, which suggests that NBCn1 is involved in the establishment of cell-matrix adhesion. Our data highlight the physiological significance of NBCn1 in modulating epithelial pH homeostasis and cell-matrix interactions in the proliferative region of the colonic epithelium and unravel the molecular mechanism behind pathological overexpression of this transporter in human colorectal cancers.NEW & NOTEWORTHY The transporter NBCn1 plays a central role in maintaining homeostasis within Caco2BBe colonic epithelial cells through its regulation of intracellular pH, matrix adhesion, migration, and proliferation. These observations yield valuable insights into the molecular mechanism of the aberrant upregulation of this transporter in human colorectal cancers.
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Affiliation(s)
- Min Jiang
- Department of Gastroenterology, Hepatology, Infectious Diseases and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Azam Salari
- Department of Gastroenterology, Hepatology, Infectious Diseases and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Christian Stock
- Department of Gastroenterology, Hepatology, Infectious Diseases and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Katerina Nikolovska
- Department of Gastroenterology, Hepatology, Infectious Diseases and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Mahdi Amiri
- Department of Gastroenterology, Hepatology, Infectious Diseases and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Ursula E Seidler
- Department of Gastroenterology, Hepatology, Infectious Diseases and Endocrinology, Hannover Medical School, Hannover, Germany
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Axelsen TV, Olesen C, Khan D, Mohammadi A, Bouzinova EV, Nielsen CJF, Mele M, Hauerslev KR, Pedersen HL, Balling E, Vahl P, Tramm T, Christiansen PM, Boedtkjer E. Antibodies toward Na +,HCO 3--cotransporter NBCn1/SLC4A7 block net acid extrusion and cause pH-dependent growth inhibition and apoptosis in breast cancer. Br J Cancer 2024; 130:1206-1220. [PMID: 38310186 PMCID: PMC10991555 DOI: 10.1038/s41416-024-02591-0] [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: 09/20/2023] [Revised: 01/09/2024] [Accepted: 01/17/2024] [Indexed: 02/05/2024] Open
Abstract
BACKGROUND Na+,HCO3--cotransporter NBCn1/Slc4a7 accelerates murine breast carcinogenesis. Lack of specific pharmacological tools previously restricted therapeutic targeting of NBCn1 and identification of NBCn1-dependent functions in human breast cancer. METHODS We develop extracellularly-targeted anti-NBCn1 antibodies, screen for functional activity on cells, and evaluate (a) mechanisms of intracellular pH regulation in human primary breast carcinomas, (b) proliferation, cell death, and tumor growth consequences of NBCn1 in triple-negative breast cancer, and (c) association of NBCn1-mediated Na+,HCO3--cotransport with human breast cancer metastasis. RESULTS We identify high-affinity (KD ≈ 0.14 nM) anti-NBCn1 antibodies that block human NBCn1-mediated Na+,HCO3--cotransport in cells, without cross-reactivity towards human NBCe1 or murine NBCn1. These anti-NBCn1 antibodies abolish Na+,HCO3--cotransport activity in freshly isolated primary organoids from human breast carcinomas and lower net acid extrusion effectively in primary breast cancer tissue from patients with macrometastases in axillary lymph nodes. Inhibitory anti-NBCn1 antibodies decelerate tumor growth in vivo by ~50% in a patient-derived xenograft model of triple-negative breast cancer and pH-dependently reduce colony formation, cause G2/M-phase cell cycle accumulation, and increase apoptosis of metastatic triple-negative breast cancer cells in vitro. CONCLUSIONS Inhibitory anti-NBCn1 antibodies block net acid extrusion in human breast cancer tissue, particularly from patients with disseminated disease, and pH-dependently limit triple-negative breast cancer growth.
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Affiliation(s)
- Trine V Axelsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Claus Olesen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Danish Khan
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Ali Mohammadi
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | | | - Marco Mele
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
| | - Katrine R Hauerslev
- Department of Plastic and Breast Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Helene L Pedersen
- Department of Pathology, Randers Regional Hospital, Randers, Denmark
| | - Eva Balling
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
| | - Pernille Vahl
- Department of Pathology, Aarhus University Hospital, Aarhus, Denmark
| | - Trine Tramm
- Department of Pathology, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Peer M Christiansen
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
- Department of Plastic and Breast Surgery, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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Stock C. pH-regulated single cell migration. Pflugers Arch 2024; 476:639-658. [PMID: 38214759 PMCID: PMC11006768 DOI: 10.1007/s00424-024-02907-2] [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: 11/22/2023] [Revised: 12/21/2023] [Accepted: 01/02/2024] [Indexed: 01/13/2024]
Abstract
Over the last two decades, extra- and intracellular pH have emerged as fundamental regulators of cell motility. Fundamental physiological and pathological processes relying on appropriate cell migration, such as embryonic development, wound healing, and a proper immune defense on the one hand, and autoimmune diseases, metastatic cancer, and the progression of certain parasitic diseases on the other, depend on surrounding pH. In addition, migrating single cells create their own localized pH nanodomains at their surface and in the cytosol. By this means, the migrating cells locally modulate their adhesion to, and the re-arrangement and digestion of, the extracellular matrix. At the same time, the cytosolic nanodomains tune cytoskeletal dynamics along the direction of movement resulting in concerted lamellipodia protrusion and rear end retraction. Extracellular pH gradients as found in wounds, inflamed tissues, or the periphery of tumors stimulate directed cell migration, and long-term exposure to acidic conditions can engender a more migratory and invasive phenotype persisting for hours up to several generations of cells after they have left the acidic milieu. In the present review, the different variants of pH-dependent single cell migration are described. The underlying pH-dependent molecular mechanisms such as conformational changes of adhesion molecules, matrix protease activity, actin (de-)polymerization, and signaling events are explained, and molecular pH sensors stimulated by H+ signaling are presented.
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Affiliation(s)
- Christian Stock
- Department of Gastroenterology, Hepatology, Infectiology & Endocrinology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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4
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Boedtkjer E, Ara T. Strengthening the basics: acids and bases influence vascular structure and function, tissue perfusion, blood pressure, and human cardiovascular disease. Pflugers Arch 2024; 476:623-637. [PMID: 38383822 DOI: 10.1007/s00424-024-02926-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/08/2024] [Accepted: 02/09/2024] [Indexed: 02/23/2024]
Abstract
Acids and their conjugate bases accumulate in or dissipate from the interstitial space when tissue perfusion does not match the metabolic demand. Extracellular acidosis dilates most arterial beds, but associated acid-base disturbances-e.g., intracellular acidification and decreases in HCO3- concentration-can also elicit pro-contractile influences that diminish vasodilation and even dominate in some vascular beds to cause vasoconstriction. The ensemble activities of the acid-base-sensitive reactions in vascular smooth muscle and endothelial cells optimize vascular resistance for blood pressure control and direct the perfusion towards active tissue. In this review, we describe the mechanisms of intracellular pH regulation in the vascular wall and discuss how vascular smooth muscle and endothelial cells sense acid-base disturbances. We further deliberate on the functional effects of local acid-base disturbances and their integrated cardiovascular consequences under physiological and pathophysiological conditions. Finally, we address how mutations and polymorphisms in the molecular machinery that regulates pH locally and senses acid-base disturbances in the vascular wall can result in cardiovascular disease. Based on the emerging molecular insight, we propose that targeting local pH-dependent effectors-rather than systemic acid-base disturbances-has therapeutic potential to interfere with the progression and reduce the severity of cardiovascular disease.
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Affiliation(s)
- Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, DK-8000, Aarhus, Denmark.
| | - Tarannum Ara
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, DK-8000, Aarhus, Denmark
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5
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Pedersen SHF. Acid-base transporters in the context of tumor heterogeneity. Pflugers Arch 2024; 476:689-701. [PMID: 38332178 DOI: 10.1007/s00424-024-02918-z] [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: 12/01/2023] [Revised: 01/20/2024] [Accepted: 01/29/2024] [Indexed: 02/10/2024]
Abstract
The copious metabolic acid production and -extrusion by cancer cells render poorly vascularized regions of solid tumors highly acidic. A growing list of proton - and bicarbonate transporters has been suggested to contribute to net acid extrusion from cancer cells, and/or been shown to be dysregulated and favor malignant development in various cancers. The great majority of these roles have been studied at the level of the cancer cells. However, recent advances in understanding of the cellular and physicochemical heterogeneity of solid tumors both enable and necessitate a reexamination of the regulation and roles of acid-base transporters in such malignancies. This review will briefly summarize the state-of-the-art, with a focus on the SLC9A and SLC4A families, for which most evidence is available. This is followed by a discussion of key concepts and open questions arising from recent insights and of the challenges that need to be tackled to address them. Finally, opportunities and challenges in therapeutic targeting of the acid-base transportome in cancers will be addressed.
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Affiliation(s)
- Stine Helene Falsig Pedersen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen, Denmark.
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Rognant S, Baldwin SN, Pritchard HAT, Greenstein A, Calloe K, Aalkjaer C, Jepps TA. Acute, pro-contractile effects of prorenin on rat mesenteric arteries. FASEB J 2023; 37:e23282. [PMID: 37994700 DOI: 10.1096/fj.202301480] [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: 07/25/2023] [Accepted: 10/16/2023] [Indexed: 11/24/2023]
Abstract
Prorenin and the prorenin receptor ((P)RR) are important, yet controversial, members of the renin-angiotensin-aldosterone system. The ((P)RR) is expressed throughout the body, including the vasculature, however, the direct effect of prorenin on arterial contractility is yet to be determined. Within rat mesenteric arteries, immunostaining and proximity ligation assays were used to determine the interacting partners of (P)RR in freshly isolated vascular smooth muscle cells (VSMCs). Wire myography examined the functional effect of prorenin. Simultaneous changes in [Ca2+ ]i and force were recorded in arteries loaded with Fura-2AM. Spontaneously transient outward currents were recorded via perforated whole-cell patch-clamp configuration in freshly isolated VSMCs. We found that the (P)RR is located within a distance of less than 40 nm from the V-ATPase, caveolin-1, ryanodine receptors, and large conductance Ca2+ -activated K+ channels (BKCa ) in VSMCs. [Ca2+ ]i imaging and isometric tension recordings indicate that 1 nM prorenin enhanced α1-adrenoreceptor-mediated contraction, associated with an increased number of Ca2+ waves, independent of voltage-gated Ca2+ channels activation. Incubation of VSMCs with 1 nM prorenin decreased the amplitude and frequency of spontaneously transient outward currents and attenuated BKCa -mediated relaxation. Inhibition of the V-ATPase with 100 nM bafilomycin prevented prorenin-mediated inhibition of BKCa -derived relaxation. Renin (1 nM) had no effect on BKCa -mediated relaxation. In conclusion, prorenin enhances arterial contractility by inhibition of BKCa and increasing intracellular Ca2+ release. It is likely that this effect is mediated through a local shift in pH upon activation of the (P)RR and stimulation of the V-ATPase.
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Affiliation(s)
- Salomé Rognant
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Samuel N Baldwin
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Harry A T Pritchard
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, Manchester University Teaching Hospitals NHS Foundation Trust, University of Manchester, Manchester, UK
- Geoffrey Jefferson Brain Research Centre, The Manchester Academic Health Science Centre, Northern Care Alliance NHS Foundation Trust, University of Manchester, Manchester, UK
| | - Adam Greenstein
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, Manchester University Teaching Hospitals NHS Foundation Trust, University of Manchester, Manchester, UK
- Geoffrey Jefferson Brain Research Centre, The Manchester Academic Health Science Centre, Northern Care Alliance NHS Foundation Trust, University of Manchester, Manchester, UK
| | - Kirstine Calloe
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | | | - Thomas A Jepps
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
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7
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Lee S, Toft NJ, Axelsen TV, Espejo MS, Pedersen TM, Mele M, Pedersen HL, Balling E, Johansen T, Burton M, Thomassen M, Vahl P, Christiansen P, Boedtkjer E. Carbonic anhydrases reduce the acidity of the tumor microenvironment, promote immune infiltration, decelerate tumor growth, and improve survival in ErbB2/HER2-enriched breast cancer. Breast Cancer Res 2023; 25:46. [PMID: 37098526 PMCID: PMC10127511 DOI: 10.1186/s13058-023-01644-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/30/2023] [Indexed: 04/27/2023] Open
Abstract
BACKGROUND Carbonic anhydrases catalyze CO2/HCO3- buffer reactions with implications for effective H+ mobility, pH dynamics, and cellular acid-base sensing. Yet, the integrated consequences of carbonic anhydrases for cancer and stromal cell functions, their interactions, and patient prognosis are not yet clear. METHODS We combine (a) bioinformatic analyses of human proteomic data and bulk and single-cell transcriptomic data coupled to clinicopathologic and prognostic information; (b) ex vivo experimental studies of gene expression in breast tissue based on quantitative reverse transcription and polymerase chain reactions, intracellular and extracellular pH recordings based on fluorescence confocal microscopy, and immunohistochemical protein identification in human and murine breast cancer biopsies; and (c) in vivo tumor size measurements, pH-sensitive microelectrode recordings, and microdialysis-based metabolite analyses in mice with experimentally induced breast carcinomas. RESULTS Carbonic anhydrases-particularly the extracellular isoforms CA4, CA6, CA9, CA12, and CA14-undergo potent expression changes during human and murine breast carcinogenesis. In patients with basal-like/triple-negative breast cancer, elevated expression of the extracellular carbonic anhydrases negatively predicts survival, whereas, surprisingly, the extracellular carbonic anhydrases positively predict patient survival in HER2/ErbB2-enriched breast cancer. Carbonic anhydrase inhibition attenuates cellular net acid extrusion and extracellular H+ elimination from diffusion-restricted to peripheral and well-perfused regions of human and murine breast cancer tissue. Supplied in vivo, the carbonic anhydrase inhibitor acetazolamide acidifies the microenvironment of ErbB2-induced murine breast carcinomas, limits tumor immune infiltration (CD3+ T cells, CD19+ B cells, F4/80+ macrophages), lowers inflammatory cytokine (Il1a, Il1b, Il6) and transcription factor (Nfkb1) expression, and accelerates tumor growth. Supporting the immunomodulatory influences of carbonic anhydrases, patient survival benefits associated with high extracellular carbonic anhydrase expression in HER2-enriched breast carcinomas depend on the tumor inflammatory profile. Acetazolamide lowers lactate levels in breast tissue and blood without influencing breast tumor perfusion, suggesting that carbonic anhydrase inhibition lowers fermentative glycolysis. CONCLUSIONS We conclude that carbonic anhydrases (a) elevate pH in breast carcinomas by accelerating net H+ elimination from cancer cells and across the interstitial space and (b) raise immune infiltration and inflammation in ErbB2/HER2-driven breast carcinomas, restricting tumor growth and improving patient survival.
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Affiliation(s)
- Soojung Lee
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, Building 1115, DK-8000, Aarhus C, Denmark
| | - Nicolai J Toft
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, Building 1115, DK-8000, Aarhus C, Denmark
| | - Trine V Axelsen
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, Building 1115, DK-8000, Aarhus C, Denmark
| | - Maria Sofia Espejo
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, Building 1115, DK-8000, Aarhus C, Denmark
| | - Tina M Pedersen
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, Building 1115, DK-8000, Aarhus C, Denmark
| | - Marco Mele
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
| | - Helene L Pedersen
- Department of Pathology, Randers Regional Hospital, Randers, Denmark
| | - Eva Balling
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
| | - Tonje Johansen
- Department of Pathology, Randers Regional Hospital, Randers, Denmark
| | - Mark Burton
- Department of Clinical Genetics, University of Southern Denmark, Odense, Denmark
- Clinical Genome Center, University and Region of Southern Denmark, Odense, Denmark
- Department of Clinical Medicine, University of Southern Denmark, Odense, Denmark
| | - Mads Thomassen
- Department of Clinical Genetics, University of Southern Denmark, Odense, Denmark
- Clinical Genome Center, University and Region of Southern Denmark, Odense, Denmark
| | - Pernille Vahl
- Department of Pathology, Aarhus University Hospital, Aarhus, Denmark
| | - Peer Christiansen
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
- Department of Plastic and Breast Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Hoegh-Guldbergs Gade 10, Building 1115, DK-8000, Aarhus C, Denmark.
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Abstract
Significance: Cancer-associated tissue-specific lactic acidosis stimulates and mediates tumor invasion and metastasis and is druggable. Rarely, malignancy causes systemic lactic acidosis, the role of which is poorly understood. Recent Advances: The understanding of the role of lactate has shifted dramatically since its discovery. Long recognized as only a waste product, lactate has become known as an alternative metabolism substrate and a secreted nutrient that is exchanged between the tumor and the microenvironment. Tissue-specific lactic acidosis is targeted to improve the host body's anticancer defense and serves as a tool that allows the targeting of anticancer compounds. Systemic lactic acidosis is associated with poor survival. In patients with solid cancer, systemic lactic acidosis is associated with an extremely poor prognosis, as revealed by the analysis of 57 published cases in this study. Although it is considered a pathology worth treating, targeting systemic lactic acidosis in patients with solid cancer is usually inefficient. Critical Issues: Research gaps include simple questions, such as the unknown nuclear pH of the cancer cells and its effects on chemotherapy outcomes, pH sensitivity of glycosylation in cancer cells, in vivo mechanisms of response to acidosis in the absence of lactate, and overinterpretation of in vitro results that were obtained by using cells that were not preadapted to acidic environments. Future Directions: Numerous metabolism-targeting anticancer compounds induce lactatemia, lactic acidosis, or other types of acidosis. Their potential to induce acidic environments is largely overlooked, although the acidosis might contribute to a substantial portion of the observed clinical effects. Antioxid. Redox Signal. 37, 1130-1152.
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Affiliation(s)
- Petr Heneberg
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
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9
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Wang J, Zahra A, Wang Y, Wu J. Understanding the Physiological Role of Electroneutral Na+-Coupled HCO3− Cotransporter and Its Therapeutic Implications. Pharmaceuticals (Basel) 2022; 15:ph15091082. [PMID: 36145304 PMCID: PMC9505461 DOI: 10.3390/ph15091082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Acid–base homeostasis is critical for proper physiological function and pathology. The SLC4 family of HCO3− transmembrane cotransporters is one of the HCO3− transmembrane transport carriers responsible for cellular pH regulation and the uptake or secretion of HCO3− in epithelial cells. NBCn1 (SLC4A7), an electroneutral Na+/HCO3− cotransporter, is extensively expressed in several tissues and functions as a cotransporter for net acid extrusion after cellular acidification. However, the expression and activity level of NBCn1 remain elusive. In addition, NBCn1 has been involved in numerous other cellular processes such as cell volume, cell death/survival balance, transepithelial transport, as well as regulation of cell viability. This review aims to give an inclusive overview of the most recent advances in the research of NBCn1, emphasizing the basic features, regulation, and tissue-specific physiology as well as the development and application of potent inhibitors of NBCn1 transporter in cancer therapy. Research and development of targeted therapies should be carried out for NBCn1 and its associated pathways.
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Affiliation(s)
- Jingjing Wang
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Aqeela Zahra
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - YunFu Wang
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan 442000, China
| | - Jianping Wu
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan 442000, China
- Correspondence:
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10
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Ji MJ, Son KH, Hong JH. Addition of oh8dG to Cardioplegia Attenuated Myocardial Oxidative Injury through the Inhibition of Sodium Bicarbonate Cotransporter Activity. Antioxidants (Basel) 2022; 11:antiox11091641. [PMID: 36139714 PMCID: PMC9495749 DOI: 10.3390/antiox11091641] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/19/2022] [Accepted: 08/23/2022] [Indexed: 11/28/2022] Open
Abstract
The biomarker 8-hydroxy-2′-deoxyguanosine (oh8dG) is derived from oxidized nucleic acids or products of oxidant-mediated DNA damage. Enhanced sodium bicarbonate cotransporter (NBC) activity is caused by reactive oxygen species (ROS) production in ventricular myocytes. Thus, we hypothesized that cardioplegia-solution-mediated ROS generation may be involved in the regulation of NBC activity in cardiomyocytes and that oh8dG treatment may modulate ROS and associated NBC activity. Langendorff-free cardioplegia-arrested cardiac strips and cardiomyocytes were isolated to determine the NBC activity and effects of oh8dG on oxidative-stress-mediated cardiac damage markers. We first determined the histidine-tryptophan-ketoglutarate (HTK) solution mediated NBC activity in cardiac strips and cells. The oh8dG treatment attenuated NBC activity in the electroneutral or electrogenic form of NBC. Additionally, exposure to HTK solution induced ROS, whereas co-administration of oh8dG attenuated ROS-mediated NBC activity, reduced ROS levels, and decreased the expression of apoptotic markers and fibrosis-associated proteins in cardiac cells. The oh8dG-administrated cardiac tissues were also protected from enhanced HTK-induced damage markers, heat shock protein 60 and polyADP-ribose. Our results show that oh8dG has a protective role against myocardial oxidative damage and provides a useful treatment strategy for restoring cardiac function.
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Affiliation(s)
- Min Jeong Ji
- Department of Health Sciences and Technology, Lee Gil Ya Cancer and Diabetes Institute, GAIHST, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, Korea
| | - Kuk Hui Son
- Department of Thoracic and Cardiovascular Surgery, Gachon University Gil Medical Center, Gachon University, Incheon 21565, Korea
- Correspondence: (K.H.S.); (J.H.H.); Tel.: +82-32-899-6682 (J.H.H.)
| | - Jeong Hee Hong
- Department of Health Sciences and Technology, Lee Gil Ya Cancer and Diabetes Institute, GAIHST, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, Korea
- Correspondence: (K.H.S.); (J.H.H.); Tel.: +82-32-899-6682 (J.H.H.)
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Affiliation(s)
- Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Christian Aalkjaer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Carroll CP, Bolland H, Vancauwenberghe E, Collier P, Ritchie AA, Clarke PA, Grabowska AM, Harris AL, McIntyre A. Targeting hypoxia regulated sodium driven bicarbonate transporters reduces triple negative breast cancer metastasis. Neoplasia 2022; 25:41-52. [PMID: 35150959 PMCID: PMC8844412 DOI: 10.1016/j.neo.2022.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/18/2022] [Accepted: 01/21/2022] [Indexed: 11/25/2022]
Abstract
Regions of low oxygen (hypoxia) are found in >50% of breast tumours, most frequently in the more aggressive triple negative breast cancer subtype (TNBC). Metastasis is the cause of 90% of breast cancer patient deaths. Regions of tumour hypoxia tend to be more acidic and both hypoxia and acidosis increase tumour metastasis. In line with this the metastatic process is dependent on pH regulatory mechanisms. We and others have previously identified increased hypoxic expression of Na+ driven bicarbonate transporters (NDBTs) as a major mechanism of tumour pH regulation. Hypoxia induced the expression of NDBTs in TNBC, most frequently SLC4A4 and SLC4A5. NDBT inhibition (S0859) and shRNA knockdown suppressed migration (40% reduction) and invasion (70% reduction) in vitro. Tumour xenograft metastasis in vivo was significantly reduced by NDBT knockdown. To investigate the mechanism by which NDBTs support metastasis, we investigated their role in regulation of phospho-signalling, epithelial-to-mesenchymal transition (EMT) and metabolism. NDBT knockdown resulted in an attenuation in hypoxic phospho-signalling activation; most notably LYN (Y397) reduced by 75%, and LCK (Y394) by 72%. The metastatic process is associated with EMT. We showed that NDBT knockdown inhibited EMT, modulating the expression of key EMT transcription factors and ablating the expression of vimentin whilst increasing the expression of E-cadherin. NDBT knockdown also altered metabolic activity reducing overall ATP and extracellular lactate levels. These results demonstrate that targeting hypoxia-induced NDBT can be used as an approach to modulate phospho-signalling, EMT, and metabolic activity and reduce tumour migration, invasion, and metastasis in vivo.
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Affiliation(s)
- Christopher Paul Carroll
- Hypoxia and Acidosis Group, Nottingham Breast Cancer Research Centre, School of Medicine, Biodiscovery Institute, University of Nottingham
| | - Hannah Bolland
- Hypoxia and Acidosis Group, Nottingham Breast Cancer Research Centre, School of Medicine, Biodiscovery Institute, University of Nottingham
| | - Eric Vancauwenberghe
- Hypoxia and Acidosis Group, Nottingham Breast Cancer Research Centre, School of Medicine, Biodiscovery Institute, University of Nottingham
| | - Pamela Collier
- Ex Vivo Cancer Pharmacology Centre, Biodiscovery Institute, University of Nottingham
| | - Alison A Ritchie
- Ex Vivo Cancer Pharmacology Centre, Biodiscovery Institute, University of Nottingham
| | - Philip A Clarke
- Ex Vivo Cancer Pharmacology Centre, Biodiscovery Institute, University of Nottingham
| | - Anna M Grabowska
- Ex Vivo Cancer Pharmacology Centre, Biodiscovery Institute, University of Nottingham
| | - Adrian L Harris
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Alan McIntyre
- Hypoxia and Acidosis Group, Nottingham Breast Cancer Research Centre, School of Medicine, Biodiscovery Institute, University of Nottingham.
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13
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Ion Channels, Transporters, and Sensors Interact with the Acidic Tumor Microenvironment to Modify Cancer Progression. Rev Physiol Biochem Pharmacol 2021; 182:39-84. [PMID: 34291319 DOI: 10.1007/112_2021_63] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Solid tumors, including breast carcinomas, are heterogeneous but typically characterized by elevated cellular turnover and metabolism, diffusion limitations based on the complex tumor architecture, and abnormal intra- and extracellular ion compositions particularly as regards acid-base equivalents. Carcinogenesis-related alterations in expression and function of ion channels and transporters, cellular energy levels, and organellar H+ sequestration further modify the acid-base composition within tumors and influence cancer cell functions, including cell proliferation, migration, and survival. Cancer cells defend their cytosolic pH and HCO3- concentrations better than normal cells when challenged with the marked deviations in extracellular H+, HCO3-, and lactate concentrations typical of the tumor microenvironment. Ionic gradients determine the driving forces for ion transporters and channels and influence the membrane potential. Cancer and stromal cells also sense abnormal ion concentrations via intra- and extracellular receptors that modify cancer progression and prognosis. With emphasis on breast cancer, the current review first addresses the altered ion composition and the changes in expression and functional activity of ion channels and transporters in solid cancer tissue. It then discusses how ion channels, transporters, and cellular sensors under influence of the acidic tumor microenvironment shape cancer development and progression and affect the potential of cancer therapies.
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14
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Toft NJ, Axelsen TV, Pedersen HL, Mele M, Burton M, Balling E, Johansen T, Thomassen M, Christiansen PM, Boedtkjer E. Acid-base transporters and pH dynamics in human breast carcinomas predict proliferative activity, metastasis, and survival. eLife 2021; 10:68447. [PMID: 34219652 PMCID: PMC8282339 DOI: 10.7554/elife.68447] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/02/2021] [Indexed: 12/13/2022] Open
Abstract
Breast cancer heterogeneity in histology and molecular subtype influences metabolic and proliferative activity and hence the acid load on cancer cells. We hypothesized that acid-base transporters and intracellular pH (pHi) dynamics contribute inter-individual variability in breast cancer aggressiveness and prognosis. We show that Na+,HCO3- cotransport and Na+/H+ exchange dominate cellular net acid extrusion in human breast carcinomas. Na+/H+ exchange elevates pHi preferentially in estrogen receptor-negative breast carcinomas, whereas Na+,HCO3- cotransport raises pHi more in invasive lobular than ductal breast carcinomas and in higher malignancy grade breast cancer. HER2-positive breast carcinomas have elevated protein expression of Na+/H+ exchanger NHE1/SLC9A1 and Na+,HCO3- cotransporter NBCn1/SLC4A7. Increased dependency on Na+,HCO3- cotransport associates with severe breast cancer: enlarged CO2/HCO3--dependent rises in pHi predict accelerated cell proliferation, whereas enhanced CO2/HCO3--dependent net acid extrusion, elevated NBCn1 protein expression, and reduced NHE1 protein expression predict lymph node metastasis. Accordingly, we observe reduced survival for patients suffering from luminal A or basal-like/triple-negative breast cancer with high SLC4A7 and/or low SLC9A1 mRNA expression. We conclude that the molecular mechanisms of acid-base regulation depend on clinicopathological characteristics of breast cancer patients. NBCn1 expression and dependency on Na+,HCO3- cotransport for pHi regulation, measured in biopsies of human primary breast carcinomas, independently predict proliferative activity, lymph node metastasis, and patient survival.
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Affiliation(s)
- Nicolai J Toft
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Trine V Axelsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Helene L Pedersen
- Department of Pathology, Regionshospitalet Randers, Randers, Denmark
| | - Marco Mele
- Department of Surgery, Regionshospitalet Randers, Randers, Denmark
| | - Mark Burton
- Department of Clinical Genetics, University of Southern Denmark, Odense, Denmark.,Clinical Genome Center, University and Region of Southern Denmark, Odense, Denmark
| | - Eva Balling
- Department of Surgery, Regionshospitalet Randers, Randers, Denmark
| | - Tonje Johansen
- Department of Pathology, Regionshospitalet Randers, Randers, Denmark
| | - Mads Thomassen
- Department of Clinical Genetics, University of Southern Denmark, Odense, Denmark.,Clinical Genome Center, University and Region of Southern Denmark, Odense, Denmark
| | - Peer M Christiansen
- Department of Surgery, Regionshospitalet Randers, Randers, Denmark.,Department of Plastic and Breast Surgery, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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15
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Olsen JSM, Svendsen S, Berg P, Dam VS, Sorensen MV, Matchkov VV, Leipziger J, Boedtkjer E. NBCn1 Increases NH 4 + Reabsorption Across Thick Ascending Limbs, the Capacity for Urinary NH 4 + Excretion, and Early Recovery from Metabolic Acidosis. J Am Soc Nephrol 2021; 32:852-865. [PMID: 33414245 PMCID: PMC8017549 DOI: 10.1681/asn.2019060613] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 11/23/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The electroneutral Na+/HCO3 - cotransporter NBCn1 (Slc4a7) is expressed in basolateral membranes of renal medullary thick ascending limbs (mTALs). However, direct evidence that NBCn1 contributes to acid-base handling in mTALs, urinary net acid excretion, and systemic acid-base homeostasis has been lacking. METHODS Metabolic acidosis was induced in wild-type and NBCn1 knockout mice. Fluorescence-based intracellular pH recordings were performed and NH4 + transport measured in isolated perfused mTALs. Quantitative RT-PCR and immunoblotting were used to evaluate NBCn1 expression. Tissue [NH4 +] was measured in renal biopsies, NH4 + excretion and titratable acid quantified in spot urine, and arterial blood gasses evaluated in normoventilated mice. RESULTS Basolateral Na+/HCO3 - cotransport activity was similar in isolated perfused mTALs from wild-type and NBCn1 knockout mice under control conditions. During metabolic acidosis, basolateral Na+/HCO3 - cotransport activity increased four-fold in mTALs from wild-type mice, but remained unchanged in mTALs from NBCn1 knockout mice. Correspondingly, NBCn1 protein expression in wild-type mice increased ten-fold in the inner stripe of renal outer medulla during metabolic acidosis. During systemic acid loading, knockout of NBCn1 inhibited the net NH4 + reabsorption across mTALs by approximately 60%, abolished the renal corticomedullary NH4 + gradient, reduced the capacity for urinary NH4 + excretion by approximately 50%, and delayed recovery of arterial blood pH and standard [HCO3 -] from their initial decline. CONCLUSIONS During metabolic acidosis, NBCn1 is required for the upregulated basolateral HCO3 - uptake and transepithelial NH4 + reabsorption in mTALs, renal medullary NH4 + accumulation, urinary NH4 + excretion, and early recovery of arterial blood pH and standard [HCO3 -]. These findings support that NBCn1 facilitates urinary net acid excretion by neutralizing intracellular H+ released during NH4 + reabsorption across mTALs.
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Affiliation(s)
| | - Samuel Svendsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Peder Berg
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Vibeke S. Dam
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | | | - Jens Leipziger
- Department of Biomedicine, Aarhus University, Aarhus, Denmark,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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16
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Hansen KB, Staehr C, Rohde PD, Homilius C, Kim S, Nyegaard M, Matchkov VV, Boedtkjer E. PTPRG is an ischemia risk locus essential for HCO 3--dependent regulation of endothelial function and tissue perfusion. eLife 2020; 9:e57553. [PMID: 32955439 PMCID: PMC7541084 DOI: 10.7554/elife.57553] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 09/18/2020] [Indexed: 12/22/2022] Open
Abstract
Acid-base conditions modify artery tone and tissue perfusion but the involved vascular-sensing mechanisms and disease consequences remain unclear. We experimentally investigated transgenic mice and performed genetic studies in a UK-based human cohort. We show that endothelial cells express the putative HCO3--sensor receptor-type tyrosine-protein phosphatase RPTPγ, which enhances endothelial intracellular Ca2+-responses in resistance arteries and facilitates endothelium-dependent vasorelaxation only when CO2/HCO3- is present. Consistent with waning RPTPγ-dependent vasorelaxation at low [HCO3-], RPTPγ limits increases in cerebral perfusion during neuronal activity and augments decreases in cerebral perfusion during hyperventilation. RPTPγ does not influence resting blood pressure but amplifies hyperventilation-induced blood pressure elevations. Loss-of-function variants in PTPRG, encoding RPTPγ, are associated with increased risk of cerebral infarction, heart attack, and reduced cardiac ejection fraction. We conclude that PTPRG is an ischemia susceptibility locus; and RPTPγ-dependent sensing of HCO3- adjusts endothelium-mediated vasorelaxation, microvascular perfusion, and blood pressure during acid-base disturbances and altered tissue metabolism.
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Affiliation(s)
| | | | - Palle D Rohde
- Department of Chemistry and Bioscience, Aalborg UniversityAalborgDenmark
| | | | - Sukhan Kim
- Department of Biomedicine, Aarhus UniversityAarhusDenmark
| | - Mette Nyegaard
- Department of Biomedicine, Aarhus UniversityAarhusDenmark
| | | | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus UniversityAarhusDenmark
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17
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Hwang S, Shin DM, Hong JH. Protective Role of IRBIT on Sodium Bicarbonate Cotransporter-n1 for Migratory Cancer Cells. Pharmaceutics 2020; 12:pharmaceutics12090816. [PMID: 32867284 PMCID: PMC7558343 DOI: 10.3390/pharmaceutics12090816] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/19/2020] [Accepted: 08/25/2020] [Indexed: 12/17/2022] Open
Abstract
IP3 receptor-binding protein released with IP3 (IRBIT) interacts with various ion channels and transporters. An electroneutral type of sodium bicarbonate cotransporter, NBCn1, participates in cell migration, and its enhanced expression is related to cancer metastasis. The effect of IRBIT on NBCn1 and its relation to cancer cell migration remain obscure. We therefore aimed to determine the effect of IRBIT on NBCn1 and the regulation of cancer cell migration due to IRBIT-induced alterations in NBCn1 activity. Overexpression of IRBIT enhanced cancer cell migration and NBC activity. Knockdown of IRBIT or NBCn1 and treatment with an NBC-specific inhibitor, S0859, attenuated cell migration. Stimulation with oncogenic epidermal growth factor enhanced the expression of NBCn1 and migration of cancer cells by recruiting IRBIT. The recruited IRBIT stably maintained the expression of the NBCn1 transporter machinery in the plasma membrane. Combined inhibition of IRBIT and NBCn1 dramatically inhibited the migration of cancer cells. Combined modulation of IRBIT and NBCn1 offers an effective strategy for attenuating cancer metastasis.
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Affiliation(s)
- Soyoung Hwang
- Department of Physiology, College of Medicine, Department of Health Sciences and Technology, GAIHST, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, Korea;
| | - Dong Min Shin
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul 03722, Korea
- Correspondence: (D.M.S.); (J.H.H.); Tel.: +82-22-228-3051 (D.M.S.); +82-32-899-6682 (J.H.H.); Fax: +82-23-64-1085 (D.M.S.); +82-32-899-6039 (J.H.H.)
| | - Jeong Hee Hong
- Department of Physiology, College of Medicine, Department of Health Sciences and Technology, GAIHST, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, Korea;
- Correspondence: (D.M.S.); (J.H.H.); Tel.: +82-22-228-3051 (D.M.S.); +82-32-899-6682 (J.H.H.); Fax: +82-23-64-1085 (D.M.S.); +82-32-899-6039 (J.H.H.)
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18
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Rode M, Teren A, Wirkner K, Horn K, Kirsten H, Loeffler M, Scholz M, Pott J. Genome-wide association analysis of pulse wave velocity traits provide new insights into the causal relationship between arterial stiffness and blood pressure. PLoS One 2020; 15:e0237237. [PMID: 32790701 PMCID: PMC7425880 DOI: 10.1371/journal.pone.0237237] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 07/22/2020] [Indexed: 11/19/2022] Open
Abstract
Background The pathophysiology of arterial stiffness is not completely understood. Pulse wave velocity (PWV) is an established marker for arterial stiffness. We compare genetics of three PWV modes, namely carotid-femoral PWV (cfPWV), brachial-ankle (baPWV) and brachial-femoral (bfPWV), reflecting different vascular segments to analyse association with genetic variants, heritability and genetic correlation with other biological traits. Furthermore we searched for shared genetic architecture concerning PWV, blood pressure (BP) and coronary artery disease (CAD) and examined the causal relationship between PWV and BP. Methods and results We performed a genome-wide association study (GWAS) for cfPWV, baPWV and bfPWV in LIFE-Adult (N = 3,643–6,734). We analysed the overlap of detected genetic loci with those of BP and CAD and performed genetic correlation analyses. By bidirectional Mendelian Randomization, we assessed the causal relationships between PWV and BP. For cfPWV we identified a new locus with genome-wide significance near SLC4A7 on cytoband 3p24.1 (lead SNP rs939834: p = 2.05x10-8). We replicated a known PWV locus on cytoband 14q32.2 near RP11-61O1.1 (lead SNPs: rs17773233, p = 1.38x10-4; rs1381289, p = 1.91x10-4) For baPWV we estimated a heritability of 28% and significant genetic correlation with hypertension (rg = 0.27, p = 6.65x10-8). We showed a positive causal effect of systolic blood pressure on PWV modes (cfPWV: p = 1.51x10-4; bfPWV: p = 1.45x10-3; baPWV: p = 6.82x10-15). Conclusions We identified a new locus for arterial stiffness and successfully replicated an earlier proposed locus. PWV shares common genetic architecture with BP and CAD. BP causally affects PWV. Larger studies are required to further unravel the genetic determinants and effects of PWV.
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Affiliation(s)
- Michael Rode
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
| | - Andrej Teren
- LIFE Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
- Heart Center Leipzig, Leipzig, Germany
| | - Kerstin Wirkner
- LIFE Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - Katrin Horn
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
- LIFE Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - Holger Kirsten
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
- LIFE Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - Markus Loeffler
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
- LIFE Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - Markus Scholz
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
- LIFE Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
- Leipzig University Medical Center, IFB Adiposity Diseases, Leipzig, Germany
- * E-mail:
| | - Janne Pott
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
- LIFE Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
- Leipzig University Medical Center, IFB Adiposity Diseases, Leipzig, Germany
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19
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Zhang Y, Zhang Y, Sun K, Meng Z, Chen L. The SLC transporter in nutrient and metabolic sensing, regulation, and drug development. J Mol Cell Biol 2020; 11:1-13. [PMID: 30239845 PMCID: PMC6359923 DOI: 10.1093/jmcb/mjy052] [Citation(s) in RCA: 129] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/18/2018] [Indexed: 02/07/2023] Open
Abstract
The prevalence of metabolic diseases is growing worldwide. Accumulating evidence suggests that solute carrier (SLC) transporters contribute to the etiology of various metabolic diseases. Consistent with metabolic characteristics, the top five organs in which SLC transporters are highly expressed are the kidney, brain, liver, gut, and heart. We aim to understand the molecular mechanisms of important SLC transporter-mediated physiological processes and their potentials as drug targets. SLC transporters serve as ‘metabolic gate’ of cells and mediate the transport of a wide range of essential nutrients and metabolites such as glucose, amino acids, vitamins, neurotransmitters, and inorganic/metal ions. Gene-modified animal models have demonstrated that SLC transporters participate in many important physiological functions including nutrient supply, metabolic transformation, energy homeostasis, tissue development, oxidative stress, host defense, and neurological regulation. Furthermore, the human genomic studies have identified that SLC transporters are susceptible or causative genes in various diseases like cancer, metabolic disease, cardiovascular disease, immunological disorders, and neurological dysfunction. Importantly, a number of SLC transporters have been successfully targeted for drug developments. This review will focus on the current understanding of SLCs in regulating physiology, nutrient sensing and uptake, and risk of diseases.
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Affiliation(s)
- Yong Zhang
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China.,Advanced Biotechnology and Application Research Center, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, China
| | - Yuping Zhang
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Kun Sun
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Ziyi Meng
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Ligong Chen
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
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20
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Becker HM, Deitmer JW. Transport Metabolons and Acid/Base Balance in Tumor Cells. Cancers (Basel) 2020; 12:cancers12040899. [PMID: 32272695 PMCID: PMC7226098 DOI: 10.3390/cancers12040899] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/03/2020] [Accepted: 04/04/2020] [Indexed: 02/07/2023] Open
Abstract
Solid tumors are metabolically highly active tissues, which produce large amounts of acid. The acid/base balance in tumor cells is regulated by the concerted interplay between a variety of membrane transporters and carbonic anhydrases (CAs), which cooperate to produce an alkaline intracellular, and an acidic extracellular, environment, in which cancer cells can outcompete their adjacent host cells. Many acid/base transporters form a structural and functional complex with CAs, coined "transport metabolon". Transport metabolons with bicarbonate transporters require the binding of CA to the transporter and CA enzymatic activity. In cancer cells, these bicarbonate transport metabolons have been attributed a role in pH regulation and cell migration. Another type of transport metabolon is formed between CAs and monocarboxylate transporters, which mediate proton-coupled lactate transport across the cell membrane. In this complex, CAs function as "proton antenna" for the transporter, which mediate the rapid exchange of protons between the transporter and the surroundings. These transport metabolons do not require CA catalytic activity, and support the rapid efflux of lactate and protons from hypoxic cancer cells to allow sustained glycolytic activity and cell proliferation. Due to their prominent role in tumor acid/base regulation and metabolism, transport metabolons might be promising drug targets for new approaches in cancer therapy.
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Affiliation(s)
- Holger M. Becker
- Institute of Physiological Chemistry, University of Veterinary Medicine Hannover, D-30559 Hannover, Germany
- Correspondence:
| | - Joachim W. Deitmer
- Department of Biology, University of Kaiserslautern, D-67653 Kaiserslautern, Germany;
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21
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Targeting the Acidic Tumor Microenvironment: Unexpected Pro-Neoplastic Effects of Oral NaHCO 3 Therapy in Murine Breast Tissue. Cancers (Basel) 2020; 12:cancers12040891. [PMID: 32268614 PMCID: PMC7226235 DOI: 10.3390/cancers12040891] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/31/2020] [Accepted: 03/31/2020] [Indexed: 11/16/2022] Open
Abstract
The acidic tumor microenvironment modifies malignant cell behavior. Here, we study consequences of the microenvironment in breast carcinomas. Beginning at carcinogen-based breast cancer induction, we supply either regular or NaHCO3-containing drinking water to female C57BL/6j mice. We evaluate urine and blood acid-base status, tumor metabolism (microdialysis sampling), and tumor pH (pH-sensitive microelectrodes) in vivo. Based on freshly isolated epithelial organoids from breast carcinomas and normal breast tissue, we assess protein expression (immunoblotting, mass spectrometry), intracellular pH (fluorescence microscopy), and cell proliferation (bromodeoxyuridine incorporation). Oral NaHCO3 therapy increases breast tumor pH in vivo from 6.68 ± 0.04 to 7.04 ± 0.09 and intracellular pH in breast epithelial organoids by ~0.15. Breast tumors develop with median latency of 85.5 ± 8.2 days in NaHCO3-treated mice vs. 82 ± 7.5 days in control mice. Oral NaHCO3 therapy does not affect tumor growth, histopathology or glycolytic metabolism. The capacity for cellular net acid extrusion is increased in NaHCO3-treated mice and correlates negatively with breast tumor latency. Oral NaHCO3 therapy elevates proliferative activity in organoids from breast carcinomas. Changes in protein expression patterns-observed by high-throughput proteomics analyses-between cancer and normal breast tissue and in response to oral NaHCO3 therapy reveal complex influences on metabolism, cytoskeleton, cell-cell and cell-matrix interaction, and cell signaling pathways. We conclude that oral NaHCO3 therapy neutralizes the microenvironment of breast carcinomas, elevates the cellular net acid extrusion capacity, and accelerates proliferation without net effect on breast cancer development or tumor growth. We demonstrate unexpected pro-neoplastic consequences of oral NaHCO3 therapy that in breast tissue cancel out previously reported anti-neoplastic effects.
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22
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Abstract
Acidic metabolic waste products accumulate in the tumor microenvironment because of high metabolic activity and insufficient perfusion. In tumors, the acidity of the interstitial space and the relatively well-maintained intracellular pH influence cancer and stromal cell function, their mutual interplay, and their interactions with the extracellular matrix. Tumor pH is spatially and temporally heterogeneous, and the fitness advantage of cancer cells adapted to extracellular acidity is likely particularly evident when they encounter less acidic tumor regions, for instance, during invasion. Through complex effects on genetic stability, epigenetics, cellular metabolism, proliferation, and survival, the compartmentalized pH microenvironment favors cancer development. Cellular selection exacerbates the malignant phenotype, which is further enhanced by acid-induced cell motility, extracellular matrix degradation, attenuated immune responses, and modified cellular and intercellular signaling. In this review, we discuss how the acidity of the tumor microenvironment influences each stage in cancer development, from dysplasia to full-blown metastatic disease.
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Affiliation(s)
- Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Stine F. Pedersen
- Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark
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23
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Lee D, Hong JH. The Fundamental Role of Bicarbonate Transporters and Associated Carbonic Anhydrase Enzymes in Maintaining Ion and pH Homeostasis in Non-Secretory Organs. Int J Mol Sci 2020; 21:ijms21010339. [PMID: 31947992 PMCID: PMC6981687 DOI: 10.3390/ijms21010339] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/02/2020] [Accepted: 01/03/2020] [Indexed: 12/18/2022] Open
Abstract
The bicarbonate ion has a fundamental role in vital systems. Impaired bicarbonate transport leads to various diseases, including immune disorders, cystic fibrosis, tumorigenesis, kidney diseases, brain dysfunction, tooth fracture, ischemic reperfusion injury, hypertension, impaired reproductive system, and systemic acidosis. Carbonic anhydrases are involved in the mechanism of bicarbonate movement and consist of complex of bicarbonate transport systems including bicarbonate transporters. This review focused on the convergent regulation of ion homeostasis through various ion transporters including bicarbonate transporters, their regulatory enzymes, such as carbonic anhydrases, pH regulatory role, and the expression pattern of ion transporters in non-secretory systems throughout the body. Understanding the correlation between these systems will be helpful in order to obtain new insights and design potential therapeutic strategies for the treatment of pH-related disorders. In this review, we have discussed the broad prospects and challenges that remain in elucidation of bicarbonate-transport-related biological and developmental systems.
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Affiliation(s)
| | - Jeong Hee Hong
- Correspondence: ; Tel.: +82-32-899-6682; Fax: +82-32-899-6039
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24
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Jiang S, Wang X, Wei J, Zhang G, Zhang J, Xie P, Xu L, Wang L, Zhao L, Li L, Wilcox CS, Chen J, Lai EY, Liu R. NaHCO 3 Dilates Mouse Afferent Arteriole Via Na +/HCO 3- Cotransporters NBCs. Hypertension 2019; 74:1104-1112. [PMID: 31522618 DOI: 10.1161/hypertensionaha.119.13235] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sodium bicarbonate has long been used to treat chronic kidney disease. It has been demonstrated to slow the decline in glomerular filtration rate in chronic kidney disease patient; however, the mechanisms are not completely understood. We hypothesized that NaHCO3 dilates afferent arterioles (Af-Art) by stimulating nitric oxide (NO) release mediated by the Na+/HCO3- cotransporter (NBC) contributing to the elevation in glomerular filtration rate. Isolated microperfused mouse renal Af-Art, preconstricted with norepinephrine (1 µmol/L), dilated 45±2% (n=6, P<0.05) in response to NaHCO3 (44 mmol/L). Whereas, NaCl solution containing the same Na+ concentration was not effective. The mRNA for NBCn1 and NBCe1 were detected in microdissected Af-Art using reverse transcription-polymerase chain reaction and quantitative polymerase chain reaction. The Af-Art intracellular pH measured with 2',7'-bis-(2-carboxyethyl)-5-(and-6) carboxyfluorescein, acetoxymethyl ester increased significantly by 0.29±0.02 (n=6; P<0.05) in the presence of NaHCO3, which was blunted by N-cyanosulphonamide compound (S0859) that is an inhibitor of the NBC family. After clamping the intracellular pH with 10 μM nigericin, changing the bath solution pH from 7.4 to 7.8 still dilates the Af-Art by 53±4% (n=7; P<0.005) and increases NO generation by 22±3% (n=7; P<0.005). Both pH-induced NO generation and vasodilation were blocked by L-NG-Nitroarginine Methyl Ester. NaHCO3 increased NO generation in Af-Art by 19±4% (n=5; P<0.005) and elevated glomerular filtration rate in conscious mice by 36% (233 versus 318 ul/min; n=9-10; P<0.0001). S0859 and L-NG-nitroarginine methyl ester blocked NaHCO3-induced increases in NO generation and vasodilation. We conclude that NBCn1 and NBCe1 are expressed in Af-Art and that NaHCO3 dilates Af-Art via NBCs mediated by NO that increases the glomerular filtration rate.
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Affiliation(s)
- Shan Jiang
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Ximing Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.).,Shandong Provincial Hospital, Affiliated Hospital of Shandong University, Jinan, China (X.W.)
| | - Jin Wei
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Gensheng Zhang
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Jie Zhang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Peng Xie
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.)
| | - Lan Xu
- College of Public Health, University of South Florida, Tampa (L.X.)
| | - Lei Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Liang Zhao
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Physiology, School of Basic Medical Sciences, Guangzhou Medical University, China (L.Z., E.Y.L.).,Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Germany (L.Z., E.Y.L.)
| | - Lingli Li
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Division of Nephrology and Hypertension, and Hypertension Center, Georgetown University, Washington, DC (L.L., C.S.W.)
| | - Christopher S Wilcox
- Division of Nephrology and Hypertension, and Hypertension Center, Georgetown University, Washington, DC (L.L., C.S.W.)
| | - Jianghua Chen
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.)
| | - En Yin Lai
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Physiology, School of Basic Medical Sciences, Guangzhou Medical University, China (L.Z., E.Y.L.).,Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Germany (L.Z., E.Y.L.)
| | - Ruisheng Liu
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
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25
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Yang NY, Mukaibo T, Kurtz I, Melvin JE. The apical Na + -HCO 3 - cotransporter Slc4a7 (NBCn1) does not contribute to bicarbonate transport by mouse salivary gland ducts. J Cell Physiol 2019; 234:16376-16388. [PMID: 30767201 PMCID: PMC6694005 DOI: 10.1002/jcp.28306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/05/2019] [Accepted: 01/18/2019] [Indexed: 01/25/2023]
Abstract
The HCO3 - secretion mechanism in salivary glands is unclear but is thought to rely on the co-ordinated activity of multiple ion transport proteins including members of the Slc4 family of bicarbonate transporters. Slc4a7 was immunolocalized to the apical membrane of mouse submandibular duct cells. In contrast, Slc4a7 was not detected in acinar cells, and correspondingly, Slc4a7 disruption did not affect fluid secretion in response to cholinergic or β-adrenergic stimulation in the submandibular gland (SMG). Much of the Na + -dependent intracellular pH (pH i ) regulation in SMG duct cells was insensitive to 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid, S0859, and to the removal of extracellular HCO 3 - . Consistent with these latter observations, the Slc4a7 null mutation had no impact on HCO 3 - secretion nor on pH i regulation in duct cells. Taken together, our results revealed that Slc4a7 targets to the apical membrane of mouse SMG duct cells where it contributes little if any to pH i regulation or stimulated HCO 3 - secretion.
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Affiliation(s)
- Ning-Yan Yang
- Secretory Mechanisms and Dysfunctions Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA,Department of Pediatric Dentistry, Beijing Stomatological Hospital & School of Stomatology, Capital Medical University, Beijing, 100050, China
| | - Taro Mukaibo
- Secretory Mechanisms and Dysfunctions Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA,Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Kitakyushu, Fukuoka, 803-8580, Japan
| | - Ira Kurtz
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, and the Brain Research Institute, University of California, Los Angeles, CA, 90095, USA
| | - James E. Melvin
- Secretory Mechanisms and Dysfunctions Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA
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26
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CAIX Regulates Invadopodia Formation through Both a pH-Dependent Mechanism and Interplay with Actin Regulatory Proteins. Int J Mol Sci 2019; 20:ijms20112745. [PMID: 31167468 PMCID: PMC6600150 DOI: 10.3390/ijms20112745] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/24/2019] [Accepted: 05/28/2019] [Indexed: 12/11/2022] Open
Abstract
Tumor metastasis is tightly linked with invasive membrane protrusions, invadopodia, formed by actively invading tumor cells. Hypoxia and pH modulation play a role in the invadopodia formation and in their matrix degradation ability. Tumor-associated carbonic anhydrase IX (CAIX), induced by hypoxia, is essential for pH regulation and migration, predisposing it as an active component of invadopodia. To investigate this assumption, we employed silencing and inhibition of CA9, invadopodia isolation and matrix degradation assay. Quail chorioallantoic membranes with implanted tumor cells, and lung colonization assay in murine model were used to assess efficiency of in vivo invasion and the impact of CAIX targeting antibodies. We showed that CAIX co-distributes to invadopodia with cortactin, MMP14, NBCe1, and phospho-PKA. Suppression or enzymatic inhibition of CAIX leads to impaired invadopodia formation and matrix degradation. Loss of CAIX attenuated phosphorylation of Y421-cortactin and influenced molecular machinery coordinating actin polymerization essential for invadopodia growth. Treatment of tumor cells by CAIX-specific antibodies against carbonic or proteoglycan domains results in reduced invasion and extravasation in vivo. For the first time, we demonstrated in vivo localization of CAIX within invadopodia. Our findings confirm the key role of CAIX in the metastatic process and gives rationale for its targeting during anti-metastatic therapy.
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Pillai SR, Damaghi M, Marunaka Y, Spugnini EP, Fais S, Gillies RJ. Causes, consequences, and therapy of tumors acidosis. Cancer Metastasis Rev 2019; 38:205-222. [PMID: 30911978 PMCID: PMC6625890 DOI: 10.1007/s10555-019-09792-7] [Citation(s) in RCA: 183] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
While cancer is commonly described as "a disease of the genes," it is also associated with massive metabolic reprogramming that is now accepted as a disease "Hallmark." This programming is complex and often involves metabolic cooperativity between cancer cells and their surrounding stroma. Indeed, there is emerging clinical evidence that interrupting a cancer's metabolic program can improve patients' outcomes. The most commonly observed and well-studied metabolic adaptation in cancers is the fermentation of glucose to lactic acid, even in the presence of oxygen, also known as "aerobic glycolysis" or the "Warburg Effect." Much has been written about the mechanisms of the Warburg effect, and this remains a topic of great debate. However, herein, we will focus on an important sequela of this metabolic program: the acidification of the tumor microenvironment. Rather than being an epiphenomenon, it is now appreciated that this acidosis is a key player in cancer somatic evolution and progression to malignancy. Adaptation to acidosis induces and selects for malignant behaviors, such as increased invasion and metastasis, chemoresistance, and inhibition of immune surveillance. However, the metabolic reprogramming that occurs during adaptation to acidosis also introduces therapeutic vulnerabilities. Thus, tumor acidosis is a relevant therapeutic target, and we describe herein four approaches to accomplish this: (1) neutralizing acid directly with buffers, (2) targeting metabolic vulnerabilities revealed by acidosis, (3) developing acid-activatable drugs and nanomedicines, and (4) inhibiting metabolic processes responsible for generating acids in the first place.
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Affiliation(s)
- Smitha R Pillai
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Dr., Tampa, FL, 33602, USA
| | - Mehdi Damaghi
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Dr., Tampa, FL, 33602, USA
| | - Yoshinori Marunaka
- Research Institute for Clinical Physiology, Kyoto, 604-8472, Japan
- Research Center for Drug Discovery and Pharmaceutical Development Science, Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, 525-8577, Japan
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | | | - Stefano Fais
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità (National Institute of Health), Viale Regina Elena, 299, 00161, Rome, Italy.
| | - Robert J Gillies
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Dr., Tampa, FL, 33602, USA.
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29
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Flinck M, Kramer SH, Schnipper J, Andersen AP, Pedersen SF. The acid-base transport proteins NHE1 and NBCn1 regulate cell cycle progression in human breast cancer cells. Cell Cycle 2018; 17:1056-1067. [PMID: 29895196 DOI: 10.1080/15384101.2018.1464850] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Precise acid-base homeostasis is essential for maintaining normal cell proliferation and growth. Conversely, dysregulated acid-base homeostasis, with increased acid extrusion and marked extracellular acidification, is an enabling feature of solid tumors, yet the mechanisms through which intra- and extracellular pH (pHi, pHe) impact proliferation and growth are incompletely understood. The aim of this study was to determine the impact of pH, and specifically of the Na+/H+ exchanger NHE1 and Na+, HCO3- transporter NBCn1, on cell cycle progression and its regulators in human breast cancer cells. Reduction of pHe to 6.5, a common condition in tumors, significantly delayed cell cycle progression in MCF-7 human breast cancer cells. The NHE1 protein level peaked in S phase and that of NBCn1 in G2/M. Steady state pHi changed through the cell cycle, from 7.1 in early S phase to 6.8 in G2, recovering again in M phase. This pattern, as well as net acid extrusion capacity, was dependent on NHE1 and NBCn1. Accordingly, knockdown of either NHE1 or NBCn1 reduced proliferation, prolonged cell cycle progression in a manner involving S phase prolongation and delayed G2/M transition, and altered the expression pattern and phosphorylation of cell cycle regulatory proteins. Our work demonstrates, for the first time, that both NHE1 and NBCn1 regulate cell cycle progression in breast cancer cells, and we propose that this involves cell cycle phase-specific pHi regulation by the two transporters.
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Affiliation(s)
- Mette Flinck
- a Section for Cell Biology and Physiology, Department of Biology , University of Copenhagen , Copenhagen Ø , Denmark
| | - Signe Hoejland Kramer
- a Section for Cell Biology and Physiology, Department of Biology , University of Copenhagen , Copenhagen Ø , Denmark
| | - Julie Schnipper
- a Section for Cell Biology and Physiology, Department of Biology , University of Copenhagen , Copenhagen Ø , Denmark
| | - Anne Poder Andersen
- a Section for Cell Biology and Physiology, Department of Biology , University of Copenhagen , Copenhagen Ø , Denmark
| | - Stine Falsig Pedersen
- a Section for Cell Biology and Physiology, Department of Biology , University of Copenhagen , Copenhagen Ø , Denmark
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30
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Na+,HCO3–-cotransporter NBCn1 (Slc4a7) accelerates ErbB2-induced breast cancer development and tumor growth in mice. Oncogene 2018; 37:5569-5584. [DOI: 10.1038/s41388-018-0353-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/07/2018] [Accepted: 05/13/2018] [Indexed: 12/20/2022]
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31
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Rorsman NJG, Ta CM, Garnett H, Swietach P, Tammaro P. Defining the ionic mechanisms of optogenetic control of vascular tone by channelrhodopsin-2. Br J Pharmacol 2018; 175:2028-2045. [PMID: 29486056 PMCID: PMC5979753 DOI: 10.1111/bph.14183] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 01/16/2018] [Accepted: 02/14/2018] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Optogenetic control of electromechanical coupling in vascular smooth muscle cells (VSMCs) is emerging as a powerful research tool with potential applications in drug discovery and therapeutics. However, the precise ionic mechanisms involved in this control remain unclear. EXPERIMENTAL APPROACH Cell imaging, patch-clamp electrophysiology and muscle tension recordings were used to define these mechanisms over a wide range of light stimulations. KEY RESULTS Transgenic mice expressing a channelrhodopsin-2 variant [ChR2(H134R)] selectively in VSMCs were generated. Isolated VSMCs obtained from these mice demonstrated blue light-induced depolarizing whole-cell currents. Fine control of artery tone was attained by varying the intensity of the light stimulus. This arterial response was sufficient to overcome the endogenous, melanopsin-mediated, light-evoked, arterial relaxation observed in the presence of contractile agonists. Ca2+ entry through voltage-gated Ca2+ channels, and opening of plasmalemmal depolarizing channels (TMEM16A and TRPM) and intracellular IP3 receptors were involved in the ChR2(H134R)-dependent arterial response to blue light at intensities lower than ~0.1 mW·mm-2 . Light stimuli of greater intensity evoked a significant Ca2+ influx directly through ChR2(H134R) and produced marked intracellular alkalinization of VSMCs. CONCLUSIONS AND IMPLICATIONS We identified the range of light intensity allowing optical control of arterial tone, primarily by means of endogenous channels and without substantial alteration to intracellular pH. Within this range, mice expressing ChR2(H134R) in VSMCs are a powerful experimental model for achieving accurate and tuneable optical voltage-clamp of VSMCs and finely graded control of arterial tone, offering new approaches to the discovery of vasorelaxant drugs.
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Affiliation(s)
- Nils J G Rorsman
- Department of PharmacologyUniversity of OxfordOxfordUK
- OXION Initiative in Ion Channels and DiseaseUniversity of OxfordOxfordUK
| | - Chau M Ta
- Department of PharmacologyUniversity of OxfordOxfordUK
| | | | - Pawel Swietach
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Paolo Tammaro
- Department of PharmacologyUniversity of OxfordOxfordUK
- OXION Initiative in Ion Channels and DiseaseUniversity of OxfordOxfordUK
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32
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Boedtkjer E. Acid-base regulation and sensing: Accelerators and brakes in metabolic regulation of cerebrovascular tone. J Cereb Blood Flow Metab 2018; 38:588-602. [PMID: 28984162 PMCID: PMC5888856 DOI: 10.1177/0271678x17733868] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 08/10/2017] [Accepted: 09/06/2017] [Indexed: 12/29/2022]
Abstract
Metabolic regulation of cerebrovascular tone directs blood flow to areas of increased neuronal activity and during disease states partially compensates for insufficient perfusion by enhancing blood flow in collateral blood vessels. Acid-base disturbances frequently occur as result of enhanced metabolism or insufficient blood supply, but despite definitive evidence that acid-base disturbances alter arterial tone, effects of individual acid-base equivalents and the underlying signaling mechanisms are still being debated. H+ is an important intra- and extracellular messenger that modifies cerebrovascular tone. In addition, low extracellular [HCO3-] promotes cerebrovascular contraction through an endothelium-dependent mechanism. CO2 alters arterial tone development via changes in intra- and extracellular pH but it is still controversial whether CO2 also has direct vasomotor effects. Vasocontractile responses to low extracellular [HCO3-] and acute CO2-induced decreases in intracellular pH can counteract H+-mediated vasorelaxation during metabolic and respiratory acidosis, respectively, and may thereby reduce the risk of capillary damage and cerebral edema that could be consequences of unopposed vasodilation. In this review, the signaling mechanisms for acid-base equivalents in cerebral arteries and the mechanisms of intracellular pH control in the arterial wall are discussed in the context of metabolic regulation of cerebrovascular tone and local perfusion.
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Affiliation(s)
- Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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33
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Froelunde AS, Ohlenbusch M, Hansen KB, Jessen N, Kim S, Boedtkjer E. Murine breast cancer feed arteries are thin-walled with reduced α 1A-adrenoceptor expression and attenuated sympathetic vasocontraction. Breast Cancer Res 2018; 20:20. [PMID: 29566737 PMCID: PMC5863844 DOI: 10.1186/s13058-018-0952-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 03/06/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Perfusion of breast cancer tissue limits oxygen availability and metabolism but angiogenesis inhibitors have hitherto been unsuccessful for breast cancer therapy. In order to identify abnormalities and possible therapeutic targets in mature cancer arteries, we here characterize the structure and function of cancer feed arteries and corresponding control arteries from female FVB/N mice with ErbB2-induced breast cancer. METHODS We investigated the contractile function of breast cancer feed arteries and matched control arteries by isometric myography and evaluated membrane potentials and intracellular [Ca2+] using sharp electrodes and fluorescence microscopy, respectively. Arterial wall structure is assessed by transmission light microscopy of arteries mounted in wire myographs and by evaluation of histological sections using the unbiased stereological disector technique. We determined the expression of messenger RNA by reverse transcription and quantitative polymerase chain reaction and studied receptor expression by confocal microscopy of arteries labelled with the BODIPY-tagged α1-adrenoceptor antagonist prazosin. RESULTS Breast cancer feed arteries are thin-walled and produce lower tension than control arteries of similar diameter in response to norepinephrine, thromboxane-analog U46619, endothelin-1, and depolarization with elevated [K+]. Fewer layers of similarly-sized vascular smooth muscle cells explain the reduced media thickness of breast cancer arteries. Evidenced by lower media stress, norepinephrine-induced and thromboxane-induced tension development of breast cancer arteries is reduced more than is explained by the thinner media. Conversely, media stress during stimulation with endothelin-1 and elevated [K+] is similar between breast cancer and control arteries. Correspondingly, vascular smooth muscle cell depolarizations and intracellular Ca2+ responses are attenuated in breast cancer feed arteries during norepinephrine but not during endothelin-1 stimulation. Protein expression of α1-adrenoceptors and messenger RNA levels for α1A-adrenoceptors are lower in breast cancer arteries than control arteries. Sympathetic vasocontraction elicited by electrical field stimulation is inhibited by α1-adrenoceptor blockade and reduced in breast cancer feed arteries compared to control arteries. CONCLUSION Thinner media and lower α1-adrenoceptor expression weaken contractions of breast cancer feed arteries in response to sympathetic activity. We propose that abnormalities in breast cancer arteries can be exploited to modify tumor perfusion and thereby either starve cancer cells or facilitate drug and oxygen delivery during chemotherapy or radiotherapy.
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Affiliation(s)
- Anne Sofie Froelunde
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, building 1170, DK-8000, Aarhus C, Denmark
| | - Marit Ohlenbusch
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, building 1170, DK-8000, Aarhus C, Denmark
| | - Kristoffer B Hansen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, building 1170, DK-8000, Aarhus C, Denmark
| | - Nicolai Jessen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, building 1170, DK-8000, Aarhus C, Denmark
| | - Sukhan Kim
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, building 1170, DK-8000, Aarhus C, Denmark
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, building 1170, DK-8000, Aarhus C, Denmark.
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Rasmussen JK, Boedtkjer E. Carbonic anhydrase inhibitors modify intracellular pH transients and contractions of rat middle cerebral arteries during CO 2/HCO 3- fluctuations. J Cereb Blood Flow Metab 2018; 38:492-505. [PMID: 28318362 PMCID: PMC5851140 DOI: 10.1177/0271678x17699224] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The CO2/HCO3- buffer minimizes pH changes in response to acid-base loads, HCO3- provides substrate for Na+,HCO3--cotransporters and Cl-/HCO3--exchangers, and H+ and HCO3- modify vasomotor responses during acid-base disturbances. We show here that rat middle cerebral arteries express cytosolic, mitochondrial, extracellular, and secreted carbonic anhydrase isoforms that catalyze equilibration of the CO2/HCO3- buffer. Switching from CO2/HCO3--free to CO2/HCO3--containing extracellular solution results in initial intracellular acidification due to hydration of CO2 followed by gradual alkalinization due to cellular HCO3- uptake. Carbonic anhydrase inhibition decelerates the initial acidification and attenuates the associated transient vasoconstriction without affecting intracellular pH or artery tone at steady-state. Na+,HCO3--cotransport and Na+/H+-exchange activity after NH4+-prepulse-induced intracellular acidification are unaffected by carbonic anhydrase inhibition. Extracellular surface pH transients induced by transmembrane NH3 flux are evident under CO2/HCO3--free conditions but absent when the buffer capacity and apparent H+ mobility increase in the presence of CO2/HCO3- even after the inhibition of carbonic anhydrases. We conclude that (a) intracellular carbonic anhydrase activity accentuates pH transients and vasoconstriction in response to acute elevations of pCO2, (b) CO2/HCO3- minimizes extracellular surface pH transients without requiring carbonic anhydrase activity, and (c) carbonic anhydrases are not rate limiting for acid–base transport across cell membranes during recovery from intracellular acidification.
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Affiliation(s)
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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35
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Parker MD. Mouse models of SLC4-linked disorders of HCO 3--transporter dysfunction. Am J Physiol Cell Physiol 2018; 314:C569-C588. [PMID: 29384695 DOI: 10.1152/ajpcell.00301.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The SLC4 family Cl-/[Formula: see text] cotransporters (NBCe1, NBCe2, NBCn1, and NBCn2) contribute to a variety of vital physiological processes including pH regulation and epithelial fluid secretion. Accordingly, their dysfunction can have devastating effects. Disorders such as epilepsy, hemolytic anemia, glaucoma, hearing loss, osteopetrosis, and renal tubular acidosis are all genetically linked to SLC4-family gene loci. This review summarizes how studies of Slc4-modified mice have enhanced our understanding of the etiology of SLC4-linked pathologies and the interpretation of genetic linkage studies. The review also surveys the novel disease signs exhibited by Slc4-modified mice which could either be considered to presage their description in humans, or to highlight interspecific differences. Finally, novel Slc4-modified mouse models are proposed, the study of which may further our understanding of the basis and treatment of SLC4-linked disorders of [Formula: see text]-transporter dysfunction.
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Affiliation(s)
- Mark D Parker
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo , Buffalo, New York.,Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo: The State University of New York , Buffalo, New York.,State University of New York Eye Institutes, University at Buffalo: The State University of New York , Buffalo, New York
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36
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Gal D, Sipido KR, Vandevelde W. Editorial highlights from Cardiovascular Research. Cardiovasc Res 2017; 113:e64-e68. [PMID: 29186440 DOI: 10.1093/cvr/cvx210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Diane Gal
- Division of Experimental Cardiology, Department of Cardiovascular Sciences, Campus Gasthuisberg, KU Leuven, Belgium
| | - Karin R Sipido
- Division of Experimental Cardiology, Department of Cardiovascular Sciences, Campus Gasthuisberg, KU Leuven, Belgium
| | - Wouter Vandevelde
- Division of Experimental Cardiology, Department of Cardiovascular Sciences, Campus Gasthuisberg, KU Leuven, Belgium
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37
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Bonde L, Boedtkjer E. Extracellular acidosis and very low [Na + ] inhibit NBCn1- and NHE1-mediated net acid extrusion from mouse vascular smooth muscle cells. Acta Physiol (Oxf) 2017; 221:129-141. [PMID: 28319329 DOI: 10.1111/apha.12877] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 02/20/2017] [Accepted: 03/14/2017] [Indexed: 12/28/2022]
Abstract
AIM The electroneutral Na+ , HCO3- cotransporter NBCn1 and Na+ /H+ exchanger NHE1 regulate acid-base balance in vascular smooth muscle cells (VSMCs) and modify artery function and structure. Pathological conditions - notably ischaemia - can dramatically perturb intracellular (i) and extracellular (o) pH and [Na+ ]. We examined effects of low [Na+ ]o and pHo on NBCn1 and NHE1 activity in VSMCs of small arteries. METHODS We measured pHi by 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein-based fluorescence microscopy of mouse mesenteric arteries and induced intracellular acidification by NH4+ prepulse technique. RESULTS NBCn1 activity - defined as Na+ -dependent, amiloride-insensitive net base uptake with CO2 /HCO3- present - was inhibited equally when pHo decreased from 7.4 (22 mm HCO3-/5% CO2 ) by metabolic (pHo 7.1/11 mm HCO3-: 22 ± 8%; pHo 6.8/5.5 mm HCO3-: 61 ± 7%) or respiratory (pHo 7.1/10% CO2 : 35 ± 11%; pHo 6.8/20% CO2 : 56 ± 7%) acidosis. Extracellular acidosis more prominently inhibited NHE1 activity - defined as Na+ -dependent net acid extrusion without CO2 /HCO3- present - at both pHo 7.1 (45 ± 9%) and 6.8 (85 ± 5%). Independently of pHo , lowering [Na+ ]o from 140 to 70 mm reduced NBCn1 and NHE1 activity <20% whereas transport activities declined markedly (25-50%) when [Na+ ]o was reduced to 35 mm. Steady-state pHi decreased more during respiratory (ΔpHi /ΔpHo = 71 ± 4%) than metabolic (ΔpHi /ΔpHo = 30 ± 7%) acidosis. CONCLUSION Extracellular acidification inhibits NBCn1 and NHE1 activity in VSMCs. NBCn1 is equivalently inhibited when pCO2 is raised or [HCO3-]o decreased. Lowering [Na+ ]o inhibits NBCn1 and NHE1 markedly only below the typical physiological and pathophysiological range. We propose that inhibition of Na+ -dependent net acid extrusion at low pHo protects against cellular Na+ overload at the cost of intracellular acidification.
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Affiliation(s)
- L. Bonde
- Department of Biomedicine; Aarhus University; Aarhus Denmark
| | - E. Boedtkjer
- Department of Biomedicine; Aarhus University; Aarhus Denmark
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Ng FL, Boedtkjer E, Witkowska K, Ren M, Zhang R, Tucker A, Aalkjær C, Caulfield MJ, Ye S. Increased NBCn1 expression, Na+/HCO3- co-transport and intracellular pH in human vascular smooth muscle cells with a risk allele for hypertension. Hum Mol Genet 2017; 26:989-1002. [PMID: 28087731 PMCID: PMC5409084 DOI: 10.1093/hmg/ddx015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 12/21/2016] [Accepted: 12/30/2016] [Indexed: 02/05/2023] Open
Abstract
Genome-wide association studies have revealed an association between variation at the SLC4A7 locus and blood pressure. SLC4A7 encodes the electroneutral Na+/HCO3- co-transporter NBCn1 which regulates intracellular pH (pHi). We conducted a functional study of variants at this locus in primary cultures of vascular smooth muscle and endothelial cells. In both cell types, we found genotype-dependent differences for rs13082711 in DNA-nuclear protein interactions, where the risk allele is associated with increased SLC4A7 expression level, NBCn1 availability and function as reflected in elevated steady-state pHi and accelerated recovery from intracellular acidosis. However, in the presence of Na+/H+ exchange activity, the SLC4A7 genotypic effect on net base uptake and steady-state pHi persisted only in vascular smooth muscle cells but not endothelial cells. We found no discernable effect of the missense polymorphism resulting in the amino acid substitution Glu326Lys. The finding of a genotypic influence on SLC4A7 expression and pHi regulation in vascular smooth muscle cells provides an insight into the molecular mechanism underlying the association of variation at the SLC4A7 locus with blood pressure.
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Affiliation(s)
- Fu Liang Ng
- Department of Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Kate Witkowska
- Department of Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Meixia Ren
- Department of Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Ruoxin Zhang
- Department of Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Arthur Tucker
- Department of Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Christian Aalkjær
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Department of Biomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Mark J. Caulfield
- Department of Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
- To whom correspondence should be addressed at: Heart Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London EC1M 6BQ, UK. Tel: +44 2078823403; Fax: +44 2078823408; (M.J.C.); Department of Cardiovascular Sciences, University of Leicester, BHF Cardiovascular Research Centre, Glenfield Hospital, Leicester LE3 9QP, UK. Tel: +44 1162044754; Fax: +44 1162875792; (S.Y.)
| | - Shu Ye
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- NIHR Biomedical Research Centre in Cardiovascular Disease, Leicester, UK
- Shantou University Medical College, Shantou, China
- To whom correspondence should be addressed at: Heart Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London EC1M 6BQ, UK. Tel: +44 2078823403; Fax: +44 2078823408; (M.J.C.); Department of Cardiovascular Sciences, University of Leicester, BHF Cardiovascular Research Centre, Glenfield Hospital, Leicester LE3 9QP, UK. Tel: +44 1162044754; Fax: +44 1162875792; (S.Y.)
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Park HJ, Lee S, Ju E, Jones JA, Choi I. Alternative transcription of sodium/bicarbonate transporter SLC4A7 gene enhanced by single nucleotide polymorphisms. Physiol Genomics 2017; 49:167-176. [PMID: 28087757 PMCID: PMC5374452 DOI: 10.1152/physiolgenomics.00112.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/11/2017] [Accepted: 01/11/2017] [Indexed: 12/31/2022] Open
Abstract
Genome-wide association studies have identified the single nucleotide polymorphism (SNP) rs3278 in the human SLC4A7 gene as one of the marker loci for addiction vulnerability. This marker is located in an intron of the gene, and its genomic role has been unknown. In this study, we examined rs3278 and three adjacent SNPs prevalent in alcoholics for their effects on an alternative promoter that would lead to the production of the NH2-terminally truncated protein NBCn1ΔN450, missing the first 450 amino acids. Analysis of the transcription start site database and a promoter prediction algorithm identified a cluster of three promoters in intron 7 and two short CpG-rich sites in intron 6. The promoter closest to rs3278 showed strong transcription activity in luciferase reporter gene assays. Major-to-minor allele substitution at rs3278 resulted in increased transcription activity. Equivalent substitutions at adjacent rs3772723 (intron 7) and rs13077400 (exon 8) had negligible effect; however, the substitution at nonsynonymous rs3755652 (exon 8) increased the activity by more than twofold. The concomitant substitution at rs3278/rs3755652 produced an additive effect. The rs3755652 had more profound effects on the promoter than the upstream regulatory CpG sites. The amino acid change E326K caused by rs3755652 had negligible effect on transporter function. In HEK 293 cells, NBCn1ΔN450 was expressed in plasma membranes, but at significantly lower levels than the nontruncated NBCn1-E. The pH change mediated by NBCn1ΔN450 was also low. We conclude that rs3278 and rs3755652 stimulate an alternative transcription of the SLC4A7 gene, increasing the production of a defective transporter.
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Affiliation(s)
- Hae Jeong Park
- Department of Pharmacology, Kyung Hee University School of Medicine, Seoul, South Korea; and
| | - Soojung Lee
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Eunji Ju
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Jayre A Jones
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Inyeong Choi
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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