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Abstract
PURPOSE OF REVIEW Kidney development depends on outgrowth of the ureteric bud into the metanephric mesenchyme. The number of ureteric bud branching events determines the final number of nephrons, which correlates inversely with the risk for development of chronic kidney disease and arterial hypertension during lifetime. The purpose of this review is to highlight the influence of oxygen on nephrogenesis and to describe cellular mechanisms by which hypoxia can impair nephron formation. RECENT FINDINGS Although kidney development normally takes place under hypoxic conditions, nephrogenesis is impaired when oxygen availability falls below the usual range. Hypoxia-inducible factors (HIF) play an important role in linking low oxygen concentrations to the biology of nephron formation, but their effect appears to be cell type dependent. In ureteric bud cells, HIF stimulates tubulogenesis, whereas HIF stabilization in cells of the metanephric mesenchyme results in secretion of growth factors, including vascular endothelial growth factor A, which in aggregate inhibit ureteric bud branching. The balance between pro and antibranching effects may be altered in various ways, but the inhibitory effect usually seems to predominate under reduced oxygen concentrations, explaining how intrauterine hypoxia can lead to low nephron numbers. SUMMARY Oxygen availability has a complex influence on nephrogenesis. Oxygen concentrations outside an optimal low range may affect nephron endowment. Associations between placental insufficiency and increased risk for chronic kidney disease and arterial hypertension during later life may to a large extent be due to direct effects of reduced oxygen supply to the metanephric mesenchyme and mediated through the HIF pathway.
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Effect of Hypoxia on the Differentiation and the Self-Renewal of Metanephrogenic Mesenchymal Stem Cells. Stem Cells Int 2017; 2017:7168687. [PMID: 28194187 PMCID: PMC5282446 DOI: 10.1155/2017/7168687] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 11/24/2016] [Accepted: 12/07/2016] [Indexed: 12/31/2022] Open
Abstract
Hypoxia is an important and influential factor in development. The embryonic kidney is exposed to a hypoxic environment throughout its development. The Wnt/β-catenin pathway plays vital roles in the differentiation and self-renewal of metanephrogenic mesenchymal stem cells (MMSCs) from which the kidney is derived. Thus, we hypothesized that hypoxia can regulate the differentiation and pluripotency of MMSCs through the Wnt/β-catenin pathway. To test this hypothesis, MMSCs from rats at embryonic day 18.5 were cultured in normoxic (21% O2) and hypoxic (1% O2) conditions. The effects of hypoxia on differentiation, stemness, proliferation, and apoptosis of cultured MMSCs and on the activity of the Wnt/β-catenin pathway were tested. Our results revealed that the hypoxic condition increased the number of epithelial cells (E-cadherin+ or CK18+) as well the expression of markers of renal tubule epithelia cells (CDH6, Aqp1, and OPN), decreased the number and proliferation of stem cells (SIX-2+ or CITED1+), and induced apoptosis. Additionally, hypoxia reduced the expression of Wnt4 as well as its downstream molecules β-catenin, LEF-1, and Axin2. Activation of the Wnt/β-catenin pathway by LiCl or BIO modified the effects of hypoxia on the differentiation and self-renewal of MMSCs. Thus, we concluded that hypoxia induces the differentiation and inhibits the self-renewal of MMSCs by inhibiting the Wnt/β-catenin pathway. The observations further our understanding of the effects of hypoxia on kidney.
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Hemker SL, Sims-Lucas S, Ho J. Role of hypoxia during nephrogenesis. Pediatr Nephrol 2016; 31:1571-7. [PMID: 26872484 PMCID: PMC4982845 DOI: 10.1007/s00467-016-3333-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 01/20/2016] [Accepted: 01/22/2016] [Indexed: 11/26/2022]
Abstract
Mammals develop in a physiologically hypoxic state, and the oxygen tension of different tissues in the embryo is precisely controlled. Deviation from normal oxygenation, such as what occurs in placental insufficiency, can disrupt fetal development. Several studies demonstrate that intrauterine hypoxia has a negative effect on kidney development. As nascent nephrons are forming from nephron progenitors in the nephrogenic zone, they are exposed to varying oxygen tension by virtue of the development of the renal vasculature. Thus, nephrogenesis may be linked to oxygen tension. However, the mechanism(s) by which this occurs remains unclear. This review focuses on what is known about molecular mechanisms active in physiological and pathological hypoxia and their effects on kidney development.
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Affiliation(s)
- Shelby L Hemker
- Division of Nephrology, Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
- University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Rangos Research Center, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Ave, Pittsburgh, PA, 15224, USA
| | - Sunder Sims-Lucas
- Division of Nephrology, Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
- University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Rangos Research Center, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Ave, Pittsburgh, PA, 15224, USA
| | - Jacqueline Ho
- Division of Nephrology, Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA.
- University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Rangos Research Center, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Ave, Pittsburgh, PA, 15224, USA.
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Schley G, Scholz H, Kraus A, Hackenbeck T, Klanke B, Willam C, Wiesener MS, Heinze E, Burzlaff N, Eckardt KU, Buchholz B. Hypoxia inhibits nephrogenesis through paracrine Vegfa despite the ability to enhance tubulogenesis. Kidney Int 2015. [PMID: 26200943 DOI: 10.1038/ki.2015.214] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Reduced nephron number predisposes to hypertension and kidney disease. Interaction of the branching ureteric bud and surrounding mesenchymal cells determines nephron number. Since oxygen supply may be critical for intrauterine development, we tested whether hypoxia and hypoxia-inducible factor-1α (HIF-1α) influence nephrogenesis. We found that HIF-1α is required for branching of MDCK cells. In addition, culture of metanephric mouse kidneys with ureteric bud cell-specific stabilization or knockout of HIF-1α revealed a positive impact of HIF-1α on nephrogenesis. In contrast, widespread stabilization of HIF-1α in metanephric kidneys through hypoxia or HIF stabilizers impaired nephrogenesis, and pharmacological HIF inhibition enhanced nephrogenesis. Several lines of evidence suggest an inhibitory effect through the hypoxia response of mesenchymal cells. HIF-1α was expressed in mesenchymal cells during nephrogenesis. Expression of the anti-branching factors Bmp4 and Vegfa, secreted by mesenchymal cells, was increased upon HIF stabilization. The conditioned medium from hypoxic metanephric kidneys inhibited MDCK branching, which was partially rescued by Vegfa antibodies. Thus, the effect of HIF-1α on nephrogenesis appears context dependent. While HIF-1α in the ureteric bud is of importance for proper branching morphogenesis, the net effect of hypoxia-induced HIF activation in the embryonic kidney appears to be mesenchymal cell-dependent inhibition of ureter branching.
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Affiliation(s)
- Gunnar Schley
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Holger Scholz
- Department of Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Andre Kraus
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Thomas Hackenbeck
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Bernd Klanke
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Carsten Willam
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Michael S Wiesener
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Eva Heinze
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Nicolai Burzlaff
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Kai-Uwe Eckardt
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Bjoern Buchholz
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
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Tsuji K, Kitamura S, Makino H. Hypoxia-inducible factor 1α regulates branching morphogenesis during kidney development. Biochem Biophys Res Commun 2014; 447:108-14. [PMID: 24690177 DOI: 10.1016/j.bbrc.2014.03.111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 03/23/2014] [Indexed: 12/30/2022]
Abstract
The kidneys are exposed to hypoxic conditions during development. Hypoxia-inducible factor (HIF), an important mediator of the response to hypoxia, is believed to have an important role in development. However, the relationship between HIF and branching morphogenesis has not been elucidated clearly. In this study, we examined whether HIF regulates kidney development. We harvested kidneys from day 13 rat embryos (E13Ks) and cultured the organs under normoxic (20% O2/5% CO2) or hypoxic (5% O2/5% CO2) conditions. We evaluated the kidneys based on morphology and gene expression. E13Ks cultured under hypoxic conditions had significantly more ureteric bud (UB) branching than the E13Ks cultured under normoxic conditions. In addition, the mRNA levels of GDNF and GDNF receptor (GFR-α1), increased under hypoxic conditions in E13Ks. When we cultured E13Ks with the HIF-1α inhibitor digoxin or with siRNA targeting HIF-1α under hypoxic conditions, we did not observe increased UB branching. In addition, the expression of GDNF and GFR-α1 was inhibited under hypoxic conditions when the kidneys were treated with siRNA targeting HIF-1α. We also elucidated that hypoxia inhibited UB cell apoptosis and promoted the expression of FGF7 mRNA levels in metanephric mesenchymal (MM) cells in vitro. These findings suggest that hypoxic condition has important roles in inducing branching morphogenesis during kidney development. Hypoxia might mediate branching morphogenesis via not only GDNF/Ret but also FGF signaling pathway.
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Affiliation(s)
- Kenji Tsuji
- Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Shinji Kitamura
- Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
| | - Hirofumi Makino
- Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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Sebinger DDR, Unbekandt M, Ganeva VV, Ofenbauer A, Werner C, Davies JA. A novel, low-volume method for organ culture of embryonic kidneys that allows development of cortico-medullary anatomical organization. PLoS One 2010; 5:e10550. [PMID: 20479933 PMCID: PMC2866658 DOI: 10.1371/journal.pone.0010550] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 04/16/2010] [Indexed: 02/05/2023] Open
Abstract
Here, we present a novel method for culturing kidneys in low volumes of medium that offers more organotypic development compared to conventional methods. Organ culture is a powerful technique for studying renal development. It recapitulates many aspects of early development very well, but the established techniques have some disadvantages: in particular, they require relatively large volumes (1–3 mls) of culture medium, which can make high-throughput screens expensive, they require porous (filter) substrates which are difficult to modify chemically, and the organs produced do not achieve good cortico-medullary zonation. Here, we present a technique of growing kidney rudiments in very low volumes of medium–around 85 microliters–using silicone chambers. In this system, kidneys grow directly on glass, grow larger than in conventional culture and develop a clear anatomical cortico-medullary zonation with extended loops of Henle.
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Affiliation(s)
- David D. R. Sebinger
- Max Bergmann Center of Biomaterials, Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany
| | - Mathieu Unbekandt
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, Scotland
| | - Veronika V. Ganeva
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, Scotland
| | - Andreas Ofenbauer
- Max Bergmann Center of Biomaterials, Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany
| | - Carsten Werner
- Max Bergmann Center of Biomaterials, Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany
| | - Jamie A. Davies
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, Scotland
- * E-mail:
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