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Inhibition of SGLT2 co-transporter by dapagliflozin ameliorates tubular proteinuria and tubule-interstitial injury at the early stage of diabetic kidney disease. Eur J Pharmacol 2023; 942:175521. [PMID: 36681317 DOI: 10.1016/j.ejphar.2023.175521] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/20/2023]
Abstract
Diabetic kidney disease (DKD) is characterized by progressive impairment of kidney function. It has been postulated that tubule-interstitial injury, associated with tubular albuminuria, precedes glomerular damage in the early stage of DKD. Here, we wanted to determine if the development of tubule-interstitial injury at the early stage of DKD implies modulation of megalin-mediated protein reabsorption in proximal tubule epithelial cells (PTECs) by SGLT2-dependent high glucose influx. Rats with streptozotocin (STZ)-induced diabetes were treated or not with dapagliflozin (DAPA) for 8 weeks. Four experimental groups were generated: (1) CONT, control; (2) DAPA, rats treated with DAPA; (3) STZ, diabetic rats; (4) STZ + DAPA, diabetic rats treated with DAPA. No changes in glomerular structure and function were observed. The STZ group presented proteinuria and albuminuria associated with an increase in the fractional excretion of proteins. A positive correlation between glycemia and proteinuria was found. These phenomena were linked to a decrease in luminal and total megalin expression and, consequently, in albumin reabsorption in PTECs. We also observed tubule-interstitial injury characterized by an increase in urinary tubular injury biomarkers and changes in tubular histomorphometry parameters. In addition, inverse correlations were found between cortical albumin uptake and tubule-interstitial injury or glycemia. All these modifications were attenuated in the STZ + DAPA group. These results suggest that SGLT2-dependent high glucose influx into PTECs promotes a harmful effect on the PTECs, leading to the development of tubular albuminuria and tubule-interstitial injury preceding glomerular damage. These results expand current knowledge on the renoprotective effects of gliflozins.
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Smaha J, Jackuliak P, Kužma M, Max F, Binkley N, Payer J. Vitamin D Deficiency Prevalence in Hospitalized Patients with COVID-19 Significantly Decreased during the Pandemic in Slovakia from 2020 to 2022 Which Was Associated with Decreasing Mortality. Nutrients 2023; 15:1132. [PMID: 36904131 PMCID: PMC10005285 DOI: 10.3390/nu15051132] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 02/26/2023] Open
Abstract
The coronavirus disease 2019 (COVID-19) pandemic has led to changes in lifestyle, which could influence vitamin D status on a population level. The purpose of our study was to compare 25-hydroxyvitamin D (25[OH]D) levels in patients hospitalized because of severe COVID-19 during two waves of the pandemic (2020/21 vs. 2021/22). A total of 101 patients from the 2021/22 wave were compared with 101 sex- and age-matched subjects from the 2020/21 wave. Patients from both groups were hospitalized during the winter season from 1 December to 28 February. Men and women were analyzed together and separately. The mean 25(OH)D concentration increased from 17.8 ± 9.7 ng/mL to 25.2 ± 12.6 ng/mL between waves. The prevalence of vitamin D deficiency (<20 ng/mL) decreased from 82% to 54%. The prevalence of adequate serum 25(OH)D concentration (>30 ng/mL) increased from 10% to 34% (p < 0.0001). The proportion of patients with a history of vitamin D supplementation increased from 18% to 44% (p < 0.0001). Low serum 25(OH)D concentration was independently associated with mortality after adjusting for age and sex for the whole cohort of patients (p < 0.0001). The prevalence of inadequate vitamin D status in hospitalized patients with COVID-19 in Slovakia decreased significantly, probably due to a higher rate of vitamin D supplementation during the COVID-19 pandemic.
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Affiliation(s)
- Juraj Smaha
- 5th Department of Internal Medicine, Comenius University Faculty of Medicine, University Hospital, Ruzinovska 6, 826 06 Bratislava, Slovakia
| | - Peter Jackuliak
- 5th Department of Internal Medicine, Comenius University Faculty of Medicine, University Hospital, Ruzinovska 6, 826 06 Bratislava, Slovakia
| | - Martin Kužma
- 5th Department of Internal Medicine, Comenius University Faculty of Medicine, University Hospital, Ruzinovska 6, 826 06 Bratislava, Slovakia
| | - Filip Max
- Department of Pharmacology and Toxicology, Comenius University Faculty of Pharmacy, Odbojarov 10, 832 32 Bratislava, Slovakia
| | - Neil Binkley
- Department of Medicine, Geriatrics Faculty, Medical Sciences Center, University of Wisconsin, 1300 University Ave, Madison, WI 53706-1510, USA
| | - Juraj Payer
- 5th Department of Internal Medicine, Comenius University Faculty of Medicine, University Hospital, Ruzinovska 6, 826 06 Bratislava, Slovakia
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Liu W, Cao S, Ma J, Shi D, Yu L, Ye Z, Yang M, Wang B, Chen W. Exposures to volatile organic compounds, serum vitamin D, and kidney function: association and interaction assessment in the US adult population. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:7605-7616. [PMID: 36044140 DOI: 10.1007/s11356-022-22637-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
The relationships of exposures to volatile organic compounds (VOCs) with vitamin D and kidney function remain unclear. Our analyses included 6070 adults from 2003 to 2010 survey cycles of the National Health and Nutrition Examination Survey to explore associations of six VOCs with serum vitamin D, albumin-to-creatinine ratio (ACR), and estimated glomerular filtration rate (eGFR). The results suggested that dibromochloromethane was positively associated with ACR, and chloroform was inversely associated with ACR. U-shaped associations of toluene, m-/p-xylene, bromodichloromethane, and 1,4-dichlorobenzene with ACR were observed. Toluene, m-/p-xylene, and 1,4-dichlorobenzene were associated with eGFR in U-shaped manners, while bromodichloromethane and chloroform were inversely associated with eGFR. Elevation in 1,4-dichlorobenzene was associated with decrease in vitamin D, while chloroform and m-/p-xylene were in U-shaped associations with vitamin D. VOCs mixture was U-shaped associated with ACR, inversely associated with eGFR, and inversely associated with vitamin D. Vitamin D was in a U-shaped association with ACR. Vitamin D significantly interacted with VOCs on the two kidney parameters. In the US adult population, exposures to VOCs were associated with kidney function and serum vitamin D level decline, and the serum vitamin D may have interaction effects with VOCs exposures on kidney function.
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Affiliation(s)
- Wei Liu
- Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Shuting Cao
- Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Jixuan Ma
- Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Da Shi
- Food and Human Nutritional Science, Faculty of Agriculture and Food Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Linling Yu
- Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Zi Ye
- Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Meng Yang
- Wuhan Children's Hospital (Wuhan Maternal and Child Health Care Hospital), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430016, Hubei, China.
| | - Bin Wang
- Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China.
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China.
| | - Weihong Chen
- Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China.
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China.
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Bouazza A, Tahar A, AitAbderrhmane S, Saidani M, Koceir EA. Modulation of cardiometabolic risk and CardioRenal syndrome by oral vitamin D 3 supplementation in Black and White Southern Sahara residents with chronic kidney disease Stage 3: focus on racial and ethnic disparities. Ren Fail 2022; 44:1243-1262. [PMID: 35930297 PMCID: PMC9359195 DOI: 10.1080/0886022x.2022.2106244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 06/20/2022] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVES Several studies have shown that cholecalciferol supplementation (25OHD-S) in chronic kidney disease (CKD) improves kidney injury by reducing fibrosis-related vascular calcification and declining apoptosis-linked nephron damage. METHODS The oral 25OHD-S was evaluated in 60,000 IU/month/36 weeks versus in 2000 IU/d/24 weeks in CKD Stage 3 with serum 25OHD level < 20 ng/mL. The study was undertaken on 156 black subjects and 150 white subjects Southern Sahara (SS). All biomarkers of cardiometabolic (CMet) and cardiorenal (CRenal) syndrome, Renin-angiotensin-aldosterone system (RAAS) profile, secondary hyperparathyroidism (SHPT), N-terminal pro B-type natriuretic peptide (NT-proBNP), Troponin T (cTnT) and atherogenicity risk were assessed by biochemical methods. Estimate glomerular filtration rate (eGFR) by chronic CKD-EPI equation formula. Total serum vitamin D by liquid chromatography-tandem mass spectrometry (MS). RESULTS Vitamin D deficiency alters in the same manner CMet, CRenal, and others biomarkers in both groups SS; however, these disorders are more acute in blacks compared to whites SS. Oral 25OHD-S a highlighted improvement of eGFR drop, SHPT decrease, decline proteinuria, and cardiac failure risk (NT-proBNP and cTnT) attenuation. Concomitantly, 25OHD-S normalizes Renin, Aldosterone, and Angiotensin System (RAAS) activity. Nevertheless, homocysteine and Lp (a) do not modulate by 25OHD-S. CONCLUSIONS The oral vitamin D3 supplementation, according the dose, and the treatment duration does not like in black-skinned people versus to white-skinned inhabitants, while the 02 groups are native to the same Saharan environment. It emerge that a high intermittent dose through an extensive supplementation (60,000 IU/36 weeks) was more effective in black subjects. At opposite, a lower dose during a short period supplementation is sufficient (2000 IU/24 weeks) in white subjects.
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Affiliation(s)
- Asma Bouazza
- Nutrition and Dietetics in Human Pathologies Post Graduate School, Bioenergetics, Intermediary Metabolism team, Biology and Organisms Physiology laboratory, USTHB, Algiers, Algeria
| | - Amina Tahar
- Nutrition and Dietetics in Human Pathologies Post Graduate School, Bioenergetics, Intermediary Metabolism team, Biology and Organisms Physiology laboratory, USTHB, Algiers, Algeria
| | | | - Messaoud Saidani
- Clinical Nephrology Exploration Unit, Dialysis and Kidney Transplantation Unit, University Hospital Center of Beni Messous, Algiers, Algeria
| | - Elhadj-Ahmed Koceir
- Nutrition and Dietetics in Human Pathologies Post Graduate School, Bioenergetics, Intermediary Metabolism team, Biology and Organisms Physiology laboratory, USTHB, Algiers, Algeria
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5
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Long KR, Rbaibi Y, Bondi CD, Ford BR, Poholek AC, Boyd-Shiwarski CR, Tan RJ, Locker JD, Weisz OA. Cubilin-, megalin-, and Dab2-dependent transcription revealed by CRISPR/Cas9 knockout in kidney proximal tubule cells. Am J Physiol Renal Physiol 2022; 322:F14-F26. [PMID: 34747197 PMCID: PMC8698540 DOI: 10.1152/ajprenal.00259.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 11/01/2021] [Accepted: 11/01/2021] [Indexed: 01/03/2023] Open
Abstract
The multiligand receptors megalin (Lrp2) and cubilin (Cubn) and their endocytic adaptor protein Dab2 (Dab2) play essential roles in maintaining the integrity of the apical endocytic pathway of proximal tubule (PT) cells and have complex and poorly understood roles in the development of chronic kidney disease. Here, we used RNA-sequencing and CRISPR/Cas9 knockout (KO) technology in a well-differentiated cell culture model to identify PT-specific transcriptional changes that are directly consequent to the loss of megalin, cubilin, or Dab2 expression. KO of Lrp2 had the greatest transcriptional effect, and nearly all genes whose expression was affected in Cubn KO and Dab2 KO cells were also changed in Lrp2 KO cells. Pathway analysis and more granular inspection of the altered gene profiles suggested changes in pathways with immunomodulatory functions that might trigger the pathological changes observed in KO mice and patients with Donnai-Barrow syndrome. In addition, differences in transcription patterns between Lrp2 and Dab2 KO cells suggested the possibility that altered spatial signaling by aberrantly localized receptors contributes to transcriptional changes upon the disruption of PT endocytic function. A reduction in transcripts encoding sodium-glucose cotransporter isoform 2 was confirmed in Lrp2 KO mouse kidney lysates by quantitative PCR analysis. Our results highlight the role of megalin as a master regulator and coordinator of ion transport, metabolism, and endocytosis in the PT. Compared with the studies in animal models, this approach provides a means to identify PT-specific transcriptional changes that are directly consequent to the loss of these target genes.NEW & NOTEWORTHY Megalin and cubilin receptors together with their adaptor protein Dab2 represent major components of the endocytic machinery responsible for efficient uptake of filtered proteins by the proximal tubule (PT). Dab2 and megalin expression have been implicated as both positive and negative modulators of kidney disease. We used RNA sequencing to knock out CRISPR/Cas9 cubilin, megalin, and Dab2 in highly differentiated PT cells to identify PT-specific changes that are directly consequent to knockout of each component.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Agenesis of Corpus Callosum/genetics
- Agenesis of Corpus Callosum/metabolism
- Agenesis of Corpus Callosum/pathology
- Animals
- Apoptosis Regulatory Proteins/genetics
- Apoptosis Regulatory Proteins/metabolism
- CRISPR-Associated Protein 9/genetics
- CRISPR-Cas Systems
- Cells, Cultured
- Databases, Genetic
- Gene Knockout Techniques
- Gene Regulatory Networks
- Hearing Loss, Sensorineural/genetics
- Hearing Loss, Sensorineural/metabolism
- Hearing Loss, Sensorineural/pathology
- Hernias, Diaphragmatic, Congenital/genetics
- Hernias, Diaphragmatic, Congenital/metabolism
- Hernias, Diaphragmatic, Congenital/pathology
- Humans
- Kidney Tubules, Proximal/metabolism
- Kidney Tubules, Proximal/pathology
- Low Density Lipoprotein Receptor-Related Protein-2/genetics
- Low Density Lipoprotein Receptor-Related Protein-2/metabolism
- Male
- Mice, Knockout
- Monodelphis
- Myopia/genetics
- Myopia/metabolism
- Myopia/pathology
- Proteinuria/genetics
- Proteinuria/metabolism
- Proteinuria/pathology
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Renal Tubular Transport, Inborn Errors/genetics
- Renal Tubular Transport, Inborn Errors/metabolism
- Renal Tubular Transport, Inborn Errors/pathology
- Transcription, Genetic
- Mice
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Affiliation(s)
- Kimberly R Long
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Youssef Rbaibi
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Corry D Bondi
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - B Rhodes Ford
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Amanda C Poholek
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Cary R Boyd-Shiwarski
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Roderick J Tan
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Joseph D Locker
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ora A Weisz
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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Shipman KE, Weisz OA. Making a Dent in Dent Disease. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa017. [PMID: 33015630 PMCID: PMC7519470 DOI: 10.1093/function/zqaa017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/04/2020] [Accepted: 09/09/2020] [Indexed: 01/06/2023]
Abstract
Dent disease (DD) is a rare kidney disorder caused by mutations in the Cl-/H+ exchanger ClC-5. Extensive physiologic characterization of the transporter has begun to illuminate its role in endosomal ion homeostasis. Nevertheless, we have yet to understand how loss of ClC-5 function in the kidney proximal tubule impairs membrane traffic of megalin and cubilin receptors to cause the low molecular weight proteinuria characteristic of DD. This review identifies open questions that remain to be answered, evaluates the current literature addressing these questions, and suggests new testable models that may link loss of ClC-5 function to tubular proteinuria in DD.
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Affiliation(s)
- Katherine E Shipman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA,Address correspondence to O.A.W. (e-mail: )
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7
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Zmijewski MA, Carlberg C. Vitamin D receptor(s): In the nucleus but also at membranes? Exp Dermatol 2020; 29:876-884. [PMID: 32654294 DOI: 10.1111/exd.14147] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/10/2020] [Accepted: 06/25/2020] [Indexed: 12/11/2022]
Abstract
The genomic actions of the vitamin D are mediated via its biologically most potent metabolite 1α,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ) and the transcription factor vitamin D receptor (VDR). Activation of VDR by 1,25(OH)2 D3 leads to change in the expression of more 1000 genes in various human tissues. Based on (epi)genome, transcriptome and crystal structure data the molecular details of this nuclear vitamin D signalling pathway are well understood. Vitamin D is known for its role on calcium homeostasis and bone formation, but it also modulates energy metabolism, innate and adaptive immunity as well as cellular growth, differentiation and apoptosis. The observation of rapid, non-genomic effects of 1,25(OH)2 D3 at cellular membranes and in the cytosol initiated the question, whether there are alternative vitamin D-binding proteins in these cellular compartments. So far, the best candidate is the enzyme PDIA3 (protein disulphide isomerase family A member 3), which is found at various subcellular locations. Furthermore, also VDR seems to play a role in membrane-based responses to vitamin D. In this viewpoint, we will dispute whether these rapid, non-genomic pathways are a meaningful addition to the genome-wide effects of vitamin D.
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Affiliation(s)
| | - Carsten Carlberg
- School of Medicine, Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
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8
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Gao Y, Zhou S, Luu S, Glowacki J. Megalin mediates 25-hydroxyvitamin D 3 actions in human mesenchymal stem cells. FASEB J 2019; 33:7684-7693. [PMID: 30893561 DOI: 10.1096/fj.201802578r] [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: 01/08/2023]
Abstract
Osteoblast differentiation of human mesenchymal stem cells (hMSCs) is stimulated by 1α,25-dihydroxycholecalciferol [1α,25(OH)2D3] and 25-hydroxycholecalciferol [25(OH)D3]; the latter's effects require intracellular hydroxylation to 1α,25(OH)2D3. Thus, hMSCs are both a source of and target for 1α,25(OH)2D3. Megalin is a transmembrane receptor for serum d-binding protein (DBP) in kidney cells and is required for uptake of the 25(OH)D3-DBP complex. We tested the hypothesis that megalin is required for D actions in hMSCs with cells from surgically discarded marrow for RT-PCR, for effects of 25(OH)D3 and 1α,25(OH)2D3, for 1α,25(OH)2D3 biosynthesis, for osteoblastogenesis, and for small interfering RNA for megalin (si-Meg) and control (si-Ctr). In hMSCs with high constitutive megalin expression, both 1α,25(OH)2D3 and 25(OH)D3 stimulated osteoblastogenesis (P < 0.05), but only 1α,25(OH)2D3 did so in hMSCs with lower megalin (lo-Meg, P < 0.001) or in si-Meg cells (P < 0.05). In addition, 1α,25(OH)2D3 biosynthesis was significantly lower in lo-Meg (46%, P = 0.034) and in si-Meg (23%, P < 0.001) than each control. Leptin significantly stimulated megalin expression 2.1-fold in lo-Meg cells (P < 0.01). These studies show that megalin is expressed in hMSCs and is required for the biosynthesis of 1α,25(OH)2D3 and for the 25(OH)D3/DBP complex to stimulate vitamin D receptor targets and osteoblastogenesis.-Gao, Y., Zhou, S., Luu, S., Glowacki, J. Megalin mediates 25-hydroxyvitamin D3 actions in human mesenchymal stem cells.
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Affiliation(s)
- Yuan Gao
- Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Orthopedic Surgery, Xin Hua Hospital, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China
| | - Shuanhu Zhou
- Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Simon Luu
- Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Julie Glowacki
- Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Oral and Maxillofacial Surgery, Harvard School of Dental Medicine, Boston, Massachusetts, USA
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9
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Selamet U, Katz R, Ginsberg C, Rifkin DE, Fried LF, Kritchevsky SB, Hoofnagle AN, Bibbins-Domingo K, Drew D, Harris T, Newman A, Gutiérrez OM, Sarnak MJ, Shlipak MG, Ix JH. Serum Calcitriol Concentrations and Kidney Function Decline, Heart Failure, and Mortality in Elderly Community-Living Adults: The Health, Aging, and Body Composition Study. Am J Kidney Dis 2018; 72:419-428. [PMID: 29885925 PMCID: PMC6245577 DOI: 10.1053/j.ajkd.2018.03.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 03/16/2018] [Indexed: 12/19/2022]
Abstract
RATIONALE & OBJECTIVES Lower 25-hydroxyvitamin D concentrations have been associated with risk for kidney function decline, heart failure, and mortality. However, 25-hydroxyvitamin D requires conversion to its active metabolite, calcitriol, for most biological effects. The associations of calcitriol concentrations with clinical events have not been well explored. STUDY DESIGN Case-cohort study. SETTING & PARTICIPANTS Well-functioning community-living older adults aged 70 to 79 years at inception who participated in the Health, Aging, and Body Composition (Health ABC) Study. PREDICTOR Serum calcitriol measured using positive ion electrospray ionization-tandem mass spectrometry. OUTCOMES Major kidney function decline (≥30% decline in estimated glomerular filtration rate from baseline), incident heart failure (HF), and all-cause mortality during 10 years of follow-up. ANALYTIC APPROACH Baseline calcitriol concentrations were measured in a random subcohort of 479 participants and also in cases with major kidney function decline [n=397]) and incident HF (n=207) during 10 years of follow-up. Associations of serum calcitriol concentrations with these end points were evaluated using weighted Cox regression to account for the case-cohort design, while associations with mortality were assessed in the subcohort alone using unweighted Cox regression. RESULTS During 8.6 years of mean follow-up, 212 (44%) subcohort participants died. In fully adjusted models, each 1-standard deviation lower calcitriol concentration was associated with 30% higher risk for major kidney function decline (95% CI, 1.03-1.65; P=0.03). Calcitriol was not significantly associated with incident HF (HR, 1.16; 95% CI, 0.94-1.47) or mortality (HR, 1.01; 95% CI, 0.81-1.26). We observed no significant interactions between calcitriol concentrations and chronic kidney disease status, baseline intact parathyroid or fibroblast factor 23 concentrations. LIMITATIONS Observational study design, calcitriol measurements at a single time point, selective study population of older adults only of white or black race. CONCLUSIONS Lower calcitriol concentrations are independently associated with kidney function decline in community-living older adults. Future studies will be needed to clarify whether these associations reflect lower calcitriol concentrations resulting from abnormal kidney tubule dysfunction or direct mechanisms relating lower calcitriol concentrations to more rapid loss of kidney function.
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Affiliation(s)
- Umut Selamet
- Division of Nephrology, Department of Medicine, University of California Los Angeles, Los Angeles, CA
| | - Ronit Katz
- Kidney Research Institute, Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA
| | - Charles Ginsberg
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, CA; Nephrology Section, Veterans Affairs San Diego Healthcare System, San Diego, CA
| | - Dena E Rifkin
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, CA; Nephrology Section, Veterans Affairs San Diego Healthcare System, San Diego, CA; Division of Preventive Medicine, Department of Family Medicine and Public Health, University of California San Diego, San Diego, CA
| | - Linda F Fried
- Nephrology Section, Veterans Affairs Hospital, University of Pittsburgh, Pittsburgh, PA; Division of Nephrology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA; Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA
| | | | - Andrew N Hoofnagle
- Department of Laboratory Medicine, University of Washington, Seattle, WA; Department of Medicine, University of Washington, Seattle, WA
| | | | - David Drew
- Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA
| | - Tamara Harris
- Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, MD
| | - Anne Newman
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA
| | - Orlando M Gutiérrez
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL; Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL
| | - Mark J Sarnak
- Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA
| | - Michael G Shlipak
- Kidney Health Research Collaborative, San Francisco Veterans Affairs Medical Center, University of California, San Francisco, CA; Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA
| | - Joachim H Ix
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, CA; Nephrology Section, Veterans Affairs San Diego Healthcare System, San Diego, CA; Division of Preventive Medicine, Department of Family Medicine and Public Health, University of California San Diego, San Diego, CA.
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10
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Abstract
The vitamin D receptor (VDR) binds the secosteroid hormone 1,25(OH)2D3 with high affinity and regulates gene programs that control a serum calcium levels, as well as cell proliferation and differentiation. A significant focus has been to exploit the VDR in cancer settings. Although preclinical studies have been strongly encouraging, to date clinical trials have delivered equivocal findings that have paused the clinical translation of these compounds. However, it is entirely possible that mining of genomic data will help to refine precisely what are the key anticancer actions of vitamin D compounds and where these can be used most effectively.
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Affiliation(s)
- Moray J Campbell
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, The Ohio State University, 536 Parks Hall, Columbus, OH 43210, USA.
| | - Donald L Trump
- Department of Medicine, Inova Schar Cancer Institute, Virginia Commonwealth University, 3221 Gallows Road, Fairfax, VA 22031, USA
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11
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Endocytic receptor LRP2/megalin—of holoprosencephaly and renal Fanconi syndrome. Pflugers Arch 2017; 469:907-916. [DOI: 10.1007/s00424-017-1992-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 12/31/2022]
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12
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Dambal S, Giangreco AA, Acosta AM, Fairchild A, Richards Z, Deaton R, Wagner D, Vieth R, Gann PH, Kajdacsy-Balla A, Van der Kwast T, Nonn L. microRNAs and DICER1 are regulated by 1,25-dihydroxyvitamin D in prostate stroma. J Steroid Biochem Mol Biol 2017; 167:192-202. [PMID: 28089917 PMCID: PMC5304339 DOI: 10.1016/j.jsbmb.2017.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 01/06/2017] [Accepted: 01/09/2017] [Indexed: 12/31/2022]
Abstract
Vitamin D deficiency increases the risk of lethal prostate adenocarcinomas (PCa) and the majority of older men are deficient. Although PCa arises from the epithelium, the surrounding stroma has hormonal regulatory control over the epithelium and contributes to carcinogenesis. Herein, we describe regulation of microRNAs (miRs) by the active hormone dihydroxyvitamin D (1,25(OH)2D) in human prostate stroma. 1,25(OH)2D binds the vitamin D receptor (VDR) transcription factor to regulate gene expression, including miRs, which have emerged as potent regulators of protein expression. 1,25(OH)2D-regulated miRs were identified by profiling in primary human prostatic stromal cells (PrS) and three miRs, miR-126-3p, miR 154-5p and miR-21-5p were subsequently validated in laser-capture micro-dissected prostate stromal tissue from a vitamin D3 clinical trial (N=45). Regulation of these miRs by 1,25(OH)2D was VDR-dependent. Network analysis of known and putative mRNA targets of these miRs was enriched with cancer and inflammation pathways, consistent with known roles of stroma and of vitamin D in carcinogenesis. Expression of the miR processing ribonuclease, DICER1, positively correlated with vitamin D metabolite levels in the clinical trial specimens. High epithelial/stromal ratios of DICER1 were significantly associated biochemical recurrence (OR 3.1, p=0.03) in a tissue microarray of 170 matched PCa patients. In summary, these results underscore the role of the prostate stroma in regulating responses to the hormone 1,25(OH)2D and identified miRs and DICER1 as being regulated in human prostate stroma. Regulation of stromal DICER1 by 1,25(OH)2D may also have clinical relevance in protection against aggressive PCa.
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Affiliation(s)
- Shweta Dambal
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States
| | - Angeline A Giangreco
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States
| | - Andres M Acosta
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States
| | - Andrew Fairchild
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States
| | - Zachary Richards
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States
| | - Ryan Deaton
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States
| | - Dennis Wagner
- Department of Nutritional Sciences, Laboratory Medicine and Pathobiology, University of Toronto, ON, Canada
| | - Reinhold Vieth
- Department of Nutritional Sciences, Laboratory Medicine and Pathobiology, University of Toronto, ON, Canada
| | - Peter H Gann
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States; University of Illinois Cancer Center, Chicago, IL, United States
| | - Andre Kajdacsy-Balla
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States; University of Illinois Cancer Center, Chicago, IL, United States
| | | | - Larisa Nonn
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, United States; University of Illinois Cancer Center, Chicago, IL, United States.
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13
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Richards Z, Batai K, Farhat R, Shah E, Makowski A, Gann PH, Kittles R, Nonn L. Prostatic compensation of the vitamin D axis in African American men. JCI Insight 2017; 2:e91054. [PMID: 28138564 DOI: 10.1172/jci.insight.91054] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND. African American (AA) men are disproportionately affected by both prostate cancer (PCa) and vitamin D deficiency compared with European American (EA) men. Vitamin D deficiency is linked to increased PCa aggressiveness and mortality. Therefore, it has been hypothesized that vitamin D deficiency may contribute to the PCa disparity between AA and EA men. METHODS. We studied a cross sectional group of 60 PCa patients (AA, n = 31; EA, n = 29) who underwent radical prostatectomy. Vitamin D metabolites 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured in the serum and tissue by uHPLC-MS-MS. Tissue was laser capture microdissected, and gene expression was quantified by microarray. DNA isolated from whole blood was genotyped for West African ancestry markers and vitamin D-related SNPs. RESULTS. Serum concentrations of 25(OH)D were lower in AAs, but concentrations of 1,25(OH)2D in the prostate tissue were higher compared with EAs. Expression of the vitamin D receptor was higher in prostate tissue from AAs. Expression of the extracellular receptor of vitamin D binding protein, LRP2, was positively associated with West African ancestry and inversely associated with tissue 25(OH)D concentrations in AAs. CONCLUSIONS. The relationships between vitamin D binding protein LRP2 and vitamin D metabolites suggest that the prohormone is actively transported into the prostate, followed by intraprostatic conversion to the active hormone, rather than passive diffusion. These findings support the presence of a compensatory response in prostate tissue to vitamin D deficiency in AAs and reveal a previously unknown complexity involving tissue distribution of vitamin D metabolites. FUNDING. Department of Defense Prostate Cancer Research Program Idea Award for Disparities Research PC121923 (LN and RK) and the NIH 1R01MD007105 (RK).
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Affiliation(s)
- Zachary Richards
- Department of Pathology, University of Illinois at Chicago (UIC), Chicago, Illinois, USA
| | - Ken Batai
- Division of Urology, Department of Surgery, University of Arizona College of Medicine, Tucson, Arizona, USA
| | - Rachael Farhat
- Department of Pathology, University of Illinois at Chicago (UIC), Chicago, Illinois, USA
| | - Ebony Shah
- Division of Urology, Department of Surgery, University of Arizona College of Medicine, Tucson, Arizona, USA
| | | | - Peter H Gann
- Department of Pathology, University of Illinois at Chicago (UIC), Chicago, Illinois, USA
| | - Rick Kittles
- Division of Urology, Department of Surgery, University of Arizona College of Medicine, Tucson, Arizona, USA
| | - Larisa Nonn
- Department of Pathology, University of Illinois at Chicago (UIC), Chicago, Illinois, USA.,University of Illinois Cancer Center, Chicago, Illinois, USA
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14
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Costanzo PR, Knoblovits P. Vitamin D and male reproductive system. Horm Mol Biol Clin Investig 2016; 28:151-159. [PMID: 27902451 DOI: 10.1515/hmbci-2016-0049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 11/02/2016] [Indexed: 01/20/2023]
Abstract
Vitamin D deficiency is a highly prevalent worldwide condition and affects people of all ages. The most important role of vitamin D is the regulation of intestinal calcium absorption and metabolism of calcium and phosphorus to maintain muscle and bone homeostasis. Furthermore, in recent years it has been discovered that the vitamin D receptor (VDR) is widely distributed in many organs and tissues where vitamin D can perform other actions that include the modulation of the immune response, insulin secretion, anti-proliferative effect on cells of vascular smooth muscle, modulation of the renin-angiotensin-aldosterone system and regulates cell growth in several organs. The VDR is widely distributed in the male reproductive system. Vitamin D induces changes in the spermatozoa's calcium and cholesterol content and in protein phosphorylation to tyrosine/threonine residues. These changes could be involved in sperm capacitation. Vitamin D seems to regulate aromatase expression in different tissues. Studies analyzing seasonal variations of sex steroids in male populations yield conflicting results. This is probably due to the wide heterogeneity of the populations included according to age, systemic diseases and obesity.
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15
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Jennersjö P, Guldbrand H, Björne S, Länne T, Fredrikson M, Lindström T, Wijkman M, Östgren CJ, Nystrom FH. A prospective observational study of all-cause mortality in relation to serum 25-OH vitamin D3 and parathyroid hormone levels in patients with type 2 diabetes. Diabetol Metab Syndr 2015; 7:53. [PMID: 26078787 PMCID: PMC4466811 DOI: 10.1186/s13098-015-0049-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 06/01/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Low levels of vitamin D have been related to increased mortality and morbidity in several non-diabetic studies. We aimed to prospectively study relationships between serum 25-OH vitamin D3 (vitamin D) and of serum parathyroid hormone (PTH) to total mortality in type 2 diabetes. We also aimed to compare the levels of these potential risk-factors in patients with and without diabetes. METHODS The main study design was prospective and observational. We used baseline data from 472 men and 245 women who participated in the "Cardiovascular Risk factors in Patients with Diabetes-a Prospective study in Primary care" study. Patients were 55-66 years old at recruitment, and an age-matched non-diabetic sample of 129 individuals constituted controls for the baseline data. Carotid-femoral pulse-wave velocity (PWV) was measured with applanation-tonometry and carotid intima-media thickness (IMT) with ultrasound. Patients with diabetes were followed for all-cause mortality using the national Swedish Cause of Death Registry. RESULTS Levels of vitamin D were lower in patients with diabetes than in controls, also after correction for age and obesity, while PTH levels did not differ. Nine women and 24 men died during 6 years of median follow up of the final cohort (n = 698). Vitamin D levels were negatively related to all-cause mortality in men independently of age, PTH, HbA1c, waist circumference, 24-h systolic ambulatory-blood pressure (ABP) and serum-apoB (p = 0.049). This finding was also statistically significant when PWV and IMT were added to the analyses (p = 0.028) and was not affected statistically when medications were also included in the regression-analysis (p = 0.01). In the women with type 2 diabetes, levels of PTH were positively related with all-cause mortality in the corresponding calculations (p = 0.016 without PWV and IMT, p = 0.006 with PWV and IMT, p = 0.045 when also adding medications to the analysis), while levels of vitamin D was without statistical significance (p >0.9). CONCLUSIONS Serum vitamin D in men and serum PTH in women give prognostic information in terms of total-mortality that are independent of regular risk factors in addition to levels of ABP, IMT and PWV. TRIAL REGISTRATION ClinicalTrials.gov: NCT01049737.
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Affiliation(s)
- Pär Jennersjö
- />Department of Medical and Health Sciences, Linköping University, SE 581 83 Linköping, Sweden
| | - Hans Guldbrand
- />Department of Medical and Health Sciences, Linköping University, SE 581 83 Linköping, Sweden
| | - Stefan Björne
- />Department of Medical and Health Sciences, Linköping University, SE 581 83 Linköping, Sweden
| | - Toste Länne
- />Department of Medical and Health Sciences, Linköping University, SE 581 83 Linköping, Sweden
| | - Mats Fredrikson
- />Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Torbjörn Lindström
- />Department of Medical and Health Sciences, Linköping University, SE 581 83 Linköping, Sweden
| | - Magnus Wijkman
- />Department of Internal Medicine and Department of Medical and Health Sciences, Linköping University, Norrköping, Sweden
| | - Carl Johan Östgren
- />Department of Medical and Health Sciences, Linköping University, SE 581 83 Linköping, Sweden
| | - Fredrik H. Nystrom
- />Department of Medical and Health Sciences, Linköping University, SE 581 83 Linköping, Sweden
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16
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Abstract
Chronic kidney disease (CKD) has been recognized as a significant global health problem because of the increased risk of total and cardiovascular morbidity and mortality. Vitamin D deficiency or insufficiency is common in patients with CKD, and serum levels of vitamin D appear to have an inverse correlation with kidney function. Growing evidence has indicated that vitamin D deficiency may contribute to deteriorating renal function, as well as increased morbidity and mortality in patients with CKD. Recent studies have suggested that treatment with active vitamin D or its analogues can ameliorate renal injury by reducing fibrosis, apoptosis, and inflammation in animal models; this treatment also decreases proteinuria and mortality in patients with CKD. These renoprotective effects of vitamin D treatment are far beyond its classical role in the maintenance of bone and mineral metabolism, in addition to its pleiotropic effects on extra-mineral metabolism. In this review, we discuss the altered metabolism of vitamin D in kidney disease, and the potential renoprotective mechanisms of vitamin D in experimental and clinical studies. In addition, issues regarding the effects of vitamin D treatment on clinical outcomes are discussed.
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Affiliation(s)
- Chang Seong Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
| | - Soo Wan Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
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17
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Christensen EI, Birn H, Storm T, Weyer K, Nielsen R. Endocytic Receptors in the Renal Proximal Tubule. Physiology (Bethesda) 2012; 27:223-36. [DOI: 10.1152/physiol.00022.2012] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Protein reabsorption is a predominant feature of the renal proximal tubule. Animal studies show that the ability to rescue plasma proteins relies on the endocytic receptors megalin and cubilin. Recently, studies of patients with syndromes caused by dysfunctional receptors have supported the importance of these for protein clearance of human ultrafiltrate. This review focuses on the molecular biology and physiology of the receptors and their involvement in renal pathological conditions.
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Affiliation(s)
- Erik I. Christensen
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Henrik Birn
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Tina Storm
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Kathrin Weyer
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Rikke Nielsen
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
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18
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Nigwekar SU, Bhan I, Thadhani R. Ergocalciferol and Cholecalciferol in CKD. Am J Kidney Dis 2012; 60:139-56. [DOI: 10.1053/j.ajkd.2011.12.035] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 12/27/2011] [Indexed: 12/14/2022]
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19
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Qazi RA, Martin KJ. Vitamin D in kidney disease: pathophysiology and the utility of treatment. Rheum Dis Clin North Am 2012; 38:115-23. [PMID: 22525847 DOI: 10.1016/j.rdc.2012.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
CKD is associated with decreased vitamin D metabolites, both the storage form 25(OH)D and the active form 1,25-dihydroxyvitamin D. This contributes to hyperparathyroidism, and increased levels of PTH mobilize minerals from the skeleton and increase the risk for fractures. Treatment with vitamin D sterols efficiently reduces secondary hyperparathyroidism of CKD. Observational studies suggest survival and other potential benefits of vitamin D treatment in the CKD population. These observations need to be verified with controlled prospective trials.
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Affiliation(s)
- Rizwan A Qazi
- Division of Nephrology, Saint Louis University, Saint Louis, MO 63110, USA.
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20
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Molecular anatomy of the kidney: what have we learned from gene expression and functional genomics? Pediatr Nephrol 2010; 25:1005-16. [PMID: 20049614 PMCID: PMC3189493 DOI: 10.1007/s00467-009-1392-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 09/15/2009] [Accepted: 09/18/2009] [Indexed: 12/15/2022]
Abstract
The discipline of paediatric nephrology encompasses the congenital nephritic syndromes, renal dysplasias, neonatal renal tumours, early onset cystic disease, tubulopathies and vesicoureteric reflux, all of which arise due to defects in normal kidney development. Indeed, congenital anomalies of the kidney and urinary tract (CAKUT) represent 20-30% of prenatal anomalies, occurring in 1 in 500 births. Developmental biologists have studied the anatomical and morphogenetic processes involved in kidney development for the last five decades. However, with the advent of transgenic mice, the sequencing of the genome, improvements in mutation detection and the advent of functional genomics, our understanding of the molecular basis of kidney development has grown significantly. Here we discuss how the advent of new genetic and genomics approaches has added to our understanding of kidney development and paediatric renal disease, as well as identifying areas in which we are still lacking knowledge.
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21
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Qazi RA, Martin KJ. Vitamin D in kidney disease: pathophysiology and the utility of treatment. Endocrinol Metab Clin North Am 2010; 39:355-63, table of contents. [PMID: 20511057 DOI: 10.1016/j.ecl.2010.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Vitamin D physiology has gained more importance and publicity than any of its counterparts in the water- and fat-soluble vitamin groups combined. This is partly because vitamin D deficiency is still widely prevalent in the developed world and the beneficial effects are thought to extend beyond the regulation of calcium and phosphorus homeostasis alone. Vitamin D deficiency becomes even more important in the various stages of chronic kidney disease (CKD); CKD itself is also on the increase. How vitamin D physiology is altered in CKD and how the various treatment modalities can alter the morbidity and mortality associated with CKD is the topic of discussion for this article.
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Affiliation(s)
- Rizwan A Qazi
- Division of Nephrology, Saint Louis University, Saint Louis, MO 63110, USA.
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22
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Willnow TE, Nykjaer A. Cellular uptake of steroid carrier proteins--mechanisms and implications. Mol Cell Endocrinol 2010; 316:93-102. [PMID: 19646505 DOI: 10.1016/j.mce.2009.07.021] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 07/21/2009] [Accepted: 07/21/2009] [Indexed: 01/05/2023]
Abstract
Steroid hormones are believed to enter cells solely by free diffusion through the plasma membrane. However, recent studies suggest the existence of cellular uptake pathways for carrier-bound steroids. Similar to the clearance of cholesterol via lipoproteins, these pathways involve the recognition of carrier proteins by endocytic receptors on the surface of target cells, followed by internalization and cellular delivery of the bound sterols. Here, we discuss the emerging concept that steroid hormones can selectively enter steroidogenic tissues by receptor-mediated endocytosis, and we discuss the implications of these uptake pathways for steroid hormone metabolism and action in vivo.
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23
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Abstract
Abnormalities in vitamin D metabolism play a major role in the pathogenesis of secondary hyperparathyroidism in chronic kidney disease. The gradual and progressive decline in 1,25-dihydroxyvitamin D in the course of chronic kidney disease is the result of several mechanisms that limit the ability of the failing kidney to maintain the levels of 1,25-dihydroxyvitamin D despite increasing levels of parathyroid hormone. Recent observations have indicated that chronic kidney disease seems to be associated with a high incidence of nutritional vitamin D insufficiency or deficiency as manifested by decreased levels of 25-hydroxyvitamin D. This contributes to the inability to maintain the levels of 1,25-dihydroxyvitamin D; therefore, current practice guidelines suggest repleting vitamin D status by the administration of native vitamin D as a first step in the therapy of the abnormalities of bone and mineral metabolism in chronic kidney disease. The efficacy of this therapy is extremely variable, and active vitamin D sterols may be required, especially as kidney disease progresses. The importance of the abnormal vitamin D metabolism is being investigated vigorously in view of the observations that vitamin D may have important biologic actions in many tissues in addition to bone and parathyroid. Thus, observational data have suggested potential survival benefits of vitamin D sterol administration in this clinical setting, and experimental data have suggested a potential beneficial effect of vitamin D sterols on the progression of kidney disease. Further work is required to define the mechanisms involved and to examine the effects of vitamin D therapy on outcomes in randomized, controlled trials.
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Affiliation(s)
- Wisam Al-Badr
- Division of Nephrology, Saint Louis University, St. Louis, Missouri, USA
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24
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van Driel M, Koedam M, Buurman CJ, Hewison M, Chiba H, Uitterlinden AG, Pols HAP, van Leeuwen JPTM. Evidence for auto/paracrine actions of vitamin D in bone: 1alpha-hydroxylase expression and activity in human bone cells. FASEB J 2006; 20:2417-9. [PMID: 17023519 DOI: 10.1096/fj.06-6374fje] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Vitamin D is an important regulator of mineral homeostasis and bone metabolism. 1Alpha-hydroxylation of 25-(OH)D3 to form the bioactive vitamin D hormone, 1alpha,25-(OH)2D3, is classically considered to take place in the kidney. However, 1alpha-hydroxylase has been reported at extrarenal sites. Whether bone is a 1alpha,25-(OH)2D3 synthesizing tissue is not univocal. The aim of this study was to investigate an autocrine/paracrine function for 1alpha,25-(OH)2D3 in bone. We show that 1alpha-hydroxylase is expressed in human osteoblasts, as well as the vitamin D binding protein receptors megalin and cubilin. Functional analyses demonstrate that after incubation with the 1alpha-hydroxylase substrate 25-(OH)D3, the osteoblasts can produce sufficient 1alpha,25-(OH)2D3 to modulate osteoblast activity, resulting in induced alkaline phosphatase (ALP) activity, osteocalcin (OC) and CYP24 mRNA expression, and mineralization. The classical renal regulators of 1alpha-hydroxylase, parathyroid hormone, and ambient calcium do not regulate 1alpha-hydroxylase in osteoblasts. In contrast, interleukin (IL)-1beta strongly induces 1alpha-hydroxylase. Besides the bone-forming cells, we demonstrate 1alpha-hydroxylase activity in the bone resorbing cells, the osteoclasts. This is strongly dependent on osteoclast inducer RANKL. This study showing expression, activity, and functionality of 1alpha-hydroxylase unequivocally demonstrates that vitamin D can act in an auto/paracrine manner in bone.
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Affiliation(s)
- M van Driel
- Department of Internal Medicine, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
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25
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Ritter CS, Armbrecht HJ, Slatopolsky E, Brown AJ. 25-Hydroxyvitamin D(3) suppresses PTH synthesis and secretion by bovine parathyroid cells. Kidney Int 2006; 70:654-9. [PMID: 16807549 DOI: 10.1038/sj.ki.5000394] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Active vitamin D compounds repress parathyroid hormone (PTH) gene transcription and block chief cell hyperplasia, making them integral tools in the treatment of secondary hyperparathyroidism in patients with chronic kidney disease. Recently, human parathyroid glands have been shown to express 25-hydroxyvitamin D 1alpha-hydroxylase (1alphaOHase), but documentation of the 1alphaOHase activity in parathyroid cells and its potential role in activating 25-hydroxyvitamin D(3) (25(OH)D(3)) to 1,25-dihydroxyvitamin D(3) (1,25(OH)2D3) have not been reported. The relative potencies of 25(OH)D(3) and 1,25(OH)(2)D(3) in reducing PTH secretion and mRNA were determined in primary cultures of bovine parathyroid cells (bPTC). The effects of blocking 1alphaOHase activity on suppression of PTH mRNA and induction of 24-hydroxylase mRNA were examined. Vitamin D receptor (VDR) affinities were estimated by intact cell competitive binding assay. Metabolism of 25(OH)D(3) by bPTC was assessed using a radioimmunoassay that measures all 1-hydroxylated metabolites of vitamin D. 25(OH)D(3) suppressed PTH secretion and mRNA (ED(50)=2 nM), but was several hundred times less potent than 1,25(OH)(2)D(3). The lower potency of 25(OH)D(3) correlated with its lower VDR affinity. bPTCs converted 25(OH)D(3) to 1-hydroxylated metabolites, but the rate of conversion was low. Inhibition of 1alphaOHase with the cytochrome P450 inhibitor clotrimazole did not block 25(OH)D(3)-mediated suppression of PTH. Clotrimazole enhanced 24-hydroxylase mRNA induction, presumably by inhibiting catabolism of 25(OH)D(3). In conclusion, 25(OH)D(3) suppresses PTH synthesis by parathyroid cells, possibly by direct activation of the VDR.
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Affiliation(s)
- C S Ritter
- Renal Division, Washington University School of Medicine, St Louis, Missouri 63110, USA
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26
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Fisher CE, Howie SEM. The role of megalin (LRP-2/Gp330) during development. Dev Biol 2006; 296:279-97. [PMID: 16828734 DOI: 10.1016/j.ydbio.2006.06.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 04/21/2006] [Accepted: 06/05/2006] [Indexed: 11/17/2022]
Abstract
Megalin (LRP-2/GP330), a member of the LDL receptor family, is an endocytic receptor expressed mainly in polarised epithelial cells. Identified as the pathogenic autoantigen of Heymann nephritis in rats, its functions have been studied in greatest detail in adult mammalian kidney, but there is increasing recognition of its involvement in embryonic development. The megalin homologue LRP-1 is essential for growth and development in Caenorhabditis elegans and megalin plays a role in CNS development in zebrafish. There is now also evidence for a homologue in Drosophila. However, most research concerns mammalian embryogenesis; it is widely accepted to be important during forebrain development and the developing renal proximal tubule. Megalin is also expressed in lung, eye, intestine, uterus, oviduct, and male reproductive tract. It is found in yolk sacs and the outer cells of pre-implantation mouse embryos, where interactions with cubilin result in nutrient endocytosis, and it may be important during implantation. Models for megalin interaction(s) with Sonic Hedgehog (Shh) have been proposed. The importance of Shh signalling during embryogenesis is well established; how and when megalin interacts with Shh is becoming a pertinent question in developmental biology.
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Affiliation(s)
- Carolyn E Fisher
- Centre for Inflammation Research, Queen's Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH 16 4JT, Scotland, UK.
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Maritzen T, Rickheit G, Schmitt A, Jentsch TJ. Kidney-specific upregulation of vitamin D3 target genes in ClC-5 KO mice. Kidney Int 2006; 70:79-87. [PMID: 16672909 DOI: 10.1038/sj.ki.5000445] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mutations in ClC-5 cause Dent's disease, a disorder associated with low molecular weight proteinuria, hyperphosphaturia, and kidney stones. ClC-5 is a Cl(-)/H(+)-exchanger predominantly expressed in the kidney, where it facilitates the acidification of proximal tubular endosomes. The reduction in proximal tubular endocytosis resulting from a lack of ClC-5 raises the luminal concentration of filtered proteins and peptides like parathyroid hormone (PTH). The increase in PTH may explain the hyperphosphaturia observed in Dent's disease. Expression profiling, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), and hormone measurements were used to investigate whether the disruption of ClC-5 affects other signalling pathways. Although the upregulation of 25(OH)(2)-vitamin D(3) 1alpha-hydroxylase and downregulation of vitamin D(3) 24-hydroxylase suggested an increased formation of 1,25(OH)(2)-vitamin D(3), the concentration of this active metabolite was reduced in the serum of ClC-5 knockout (KO) mice. However, target genes of 1,25(OH)(2)-vitamin D(3) were upregulated in KO kidneys. Expression analysis of intestine and bone revealed that the upregulation of 1,25(OH)(2)-vitamin D(3) target genes was kidney intrinsic and not systemic. In spite of reduced serum levels of 1,25(OH)(2)-vitamin D(3) in ClC-5 KO mice, 1,25(OH)(2)-vitamin D(3) is increased in later nephron segments as a consequence of impaired proximal tubular endocytosis. This leads to a kidney-specific stimulation of 1,25(OH)(2)-vitamin D(3) target genes that may contribute to the pathogenesis of Dent's disease. The activation of genes in distal nephron segments by hormones that are normally endocytosed in the proximal tubule may extend to other pathways like those activated by retinoic acid.
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Affiliation(s)
- T Maritzen
- Zentrum für Molekulare Neurobiologie Hamburg, ZMNH, Universität Hamburg, Hamburg, Germany
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Ebert R, Schütze N, Adamski J, Jakob F. Vitamin D signaling is modulated on multiple levels in health and disease. Mol Cell Endocrinol 2006; 248:149-59. [PMID: 16406653 DOI: 10.1016/j.mce.2005.11.039] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vitamin D signaling is dependent on the availability and turnover of the active Vitamin D receptor (VDR) ligand 1,25-dihydroxycholecalciferol and on the efficiency of VDR transactivation. Activating and inactivating secosteroid metabolizing p450 enzymes, e.g. 25-hydroxylases, 1alpha-hydroxylase and 24-hydroxylase, are responsible for ligand availability on the basis of substrate production in the skin and of nutritional intake of precursors. Net availability of active hormone depends on the delivery of substrate and the balance of activating and inactivating enzymes. 1Alpha-hydroxylase is the critical activating enzyme. It is expressed in the kidney for systemic supply and in target tissues for local secosteroid activation. It is upregulated in the kidney by low calcium intake and parathyroid hormone, downregulated by phosphatonins and proinflammatory signal transduction. Transactivation of VDR depends on the correct molecule structure, effective nuclear translocation and the presence of the unliganded heterodimer partner retinoid X-receptor (RXR) and other nuclear cofactors. Rapid Vitamin D-dependent membrane associated effects and consecutive second messenger activation exert an own pattern of gene regulation. A membrane receptor for these effects is hypothesized but not yet identified. Rickets is the long known clinical syndrome of impaired Vitamin D signaling due to Vitamin D3 deficiency. It can be caused by inherited defects of the cascade, nutritional deficits, lack of sunlight exposure, malabsorption and underlying diseases like chronic inflammation. It has been shown during the last decades that many modifiers of Vitamin D signaling are targets of disease in terms of inherited and acquired syndromes and that Vitamin D signaling is modulated at multiple levels and is more complex than mere mechanistic ligand/receptor/DNA interaction.
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Affiliation(s)
- Regina Ebert
- Musculosceletal Research Center, Orthopedic Department, University of Wuerzburg, Brettreichstrasse 11, D-97074 Wuerzburg, Germany
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29
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Bajwa A, Horst RL, Beckman MJ. Gene profiling the effects of calcium deficiency versus 1,25-dihydroxyvitamin D induced hypercalcemia in rat kidney cortex. Arch Biochem Biophys 2005; 438:182-94. [PMID: 15913539 DOI: 10.1016/j.abb.2005.04.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Revised: 04/20/2005] [Accepted: 04/21/2005] [Indexed: 11/16/2022]
Abstract
Determinants involved in the activation and repression of 1,25-dihydroxyvitamin D (1,25(OH)(2)D(3)) synthesis in renal cortex by changes in extracellular Ca were studied. Cortical kidney RNA isolated from hypocalcemic (LC) rats generated by a low Ca diet, and hypercalcemic (HC) rats generated by a normal Ca diet and two sequential 1 microg doses of 1,25(OH)(2)D(3). Among the genes up-regulated were 1alpha-OHase (4.6-fold) in the LC group and high differential gene expression of VDR (4.0-fold) and 24-OHase (10.4-fold) in the HC group. Moreover, the exposure of renal cortex to LC versus HC conditions revealed a high differential expression of a PKA-dominated pathway involving CBP interacting protein, GATA-1 and CREB transcription factors in the LC model. In the HC model, elevated renal cortex gene expression of several growth factors, peptide receptors, and intracellular signaling molecules depicts a role for CaSR activation and receptor tyrosine kinase signaling in 1,25(OH)(2)D(3)-mediated gene activation and repression of 1alpha-OHase.
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Affiliation(s)
- A Bajwa
- Department of Biochemistry, Virginia Commonwealth University Medical Center, Richmond, 23298-0694, USA
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Liang M, Cowley AW, Hessner MJ, Lazar J, Basile DP, Pietrusz JL. Transcriptome analysis and kidney research: Toward systems biology. Kidney Int 2005; 67:2114-22. [PMID: 15882254 DOI: 10.1111/j.1523-1755.2005.00315.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An enormous amount of data has been generated in kidney research using transcriptome analysis techniques. In this review article, we first describe briefly the principles and major characteristics of several of these techniques. We then summarize the progress in kidney research that has been made by using transcriptome analysis, emphasizing the experience gained and the lessons learned. Several technical issues regarding DNA microarray are highlighted because of the rapidly increased use of this technology. It appears clear from this brief survey that transcriptome analysis is an effective and important tool for question-driven exploratory science. To further enhance the power of this and other high throughput, as well as conventional approaches, in future studies of the kidney, we propose a multidimensional systems biology paradigm that integrates investigation at multiple levels of biologic regulation toward the goal of achieving a global understanding of physiology and pathophysiology.
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Affiliation(s)
- Mingyu Liang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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31
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Mori K, Lee HT, Rapoport D, Drexler IR, Foster K, Yang J, Schmidt-Ott KM, Chen X, Li JY, Weiss S, Mishra J, Cheema FH, Markowitz G, Suganami T, Sawai K, Mukoyama M, Kunis C, D'Agati V, Devarajan P, Barasch J. Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury. J Clin Invest 2005. [PMID: 15711640 DOI: 10.1172/jci200523056] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with iron-binding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules. In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 microg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngal-dependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment.
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Affiliation(s)
- Kiyoshi Mori
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, USA
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Mori K, Lee HT, Rapoport D, Drexler IR, Foster K, Yang J, Schmidt-Ott KM, Chen X, Li JY, Weiss S, Mishra J, Cheema FH, Markowitz G, Suganami T, Sawai K, Mukoyama M, Kunis C, D'Agati V, Devarajan P, Barasch J. Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury. J Clin Invest 2005; 115:610-21. [PMID: 15711640 PMCID: PMC548316 DOI: 10.1172/jci23056] [Citation(s) in RCA: 673] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Accepted: 12/20/2004] [Indexed: 01/15/2023] Open
Abstract
Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with iron-binding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules. In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 microg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngal-dependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment.
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Affiliation(s)
- Kiyoshi Mori
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, USA
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Souza KLA, Elsner M, Mathias PCF, Lenzen S, Tiedge M. Cytokines activate genes of the endocytotic pathway in insulin-producing RINm5F cells. Diabetologia 2004; 47:1292-1302. [PMID: 15248046 DOI: 10.1007/s00125-004-1435-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Accepted: 05/06/2004] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Cytokines are important humoral mediators of beta cell destruction in autoimmune diabetes. The aim of this study was to identify novel cytokine-induced genes in insulin-producing RINm5F cells, which may contribute to beta cell death or survival. METHODS A global gene expression profile in cytokine-exposed insulin-producing RINm5F cells was achieved by automated restriction fragment differential display PCR. The expression of selected candidate genes was confirmed by real-time RT-PCR analysis. RESULTS Exposure of RINm5F cells to IL-1beta or to a cytokine mixture (IL-1beta, TNF-alpha, IFN-gamma) for 6 h resulted in the differential expression of a functional gene cluster. Apart from the well-known up-regulation of the cytokine-responsive genes iNOS, NF-kappaB, MnSOD and Hsp70, several genes that belong to the functional cluster of the endocytotic pathway were identified. These endocytotic genes comprised: clathrin, megalin, synaptotagmin and calcineurin, which were up-regulated by IL-1beta or the cytokine mixture. In contrast, the expression of the calcineurin inhibitor CAIN and of the GDP/GTP exchange protein Rab3 was down-regulated by cytokines. Other up-regulated cytokine-responsive genes were: agrin, murine adherent macrophage protein mRNA ( MAMA) and transport-associated protein ( TAP1/MTP), whereas the plasma membrane calcium ATPase ( PMCA) 2 and PMCA 3 genes were down-regulated by cytokines. CONCLUSIONS/INTERPRETATION Our results indicate that genes of the endocytotic pathway are regulated by pro-inflammatory cytokines. This might affect the density of cytokine receptors at the beta cell surface and concomitantly the sensitivity of the cells to cytokine toxicity. A better understanding of the functional cross-talk between endocytotic and cytokine signalling pathways could further the development of novel strategies to protect pancreatic beta cells against toxic effects of pro-inflammatory cytokines.
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Affiliation(s)
- K L A Souza
- Institute of Clinical Biochemistry, Hanover Medical School, 30623, Hanover, Germany
- Department of Cell Biology and Genetics, University of Maringá, Maringá, Brazil
| | - M Elsner
- Institute of Clinical Biochemistry, Hanover Medical School, 30623, Hanover, Germany
| | - P C F Mathias
- Department of Cell Biology and Genetics, University of Maringá, Maringá, Brazil
| | - S Lenzen
- Institute of Clinical Biochemistry, Hanover Medical School, 30623, Hanover, Germany
| | - M Tiedge
- Institute of Clinical Biochemistry, Hanover Medical School, 30623, Hanover, Germany.
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Hayden PS, El-Meanawy A, Schelling JR, Sedor JR. DNA expression analysis: serial analysis of gene expression, microarrays and kidney disease. Curr Opin Nephrol Hypertens 2003; 12:407-14. [PMID: 12815337 DOI: 10.1097/00041552-200307000-00009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Expression profiling using serial analysis of gene expression and microarray technologies allows global description of expressed genes present in biological systems. Although relatively new technologies, each having been developed in the mid-1990s, both have become established and widely used tools for identification of gene networks and gene function. RECENT FINDINGS This review highlights DNA expression analyses published in 2002, emphasizing primarily serial analysis of gene expression and microarray technologies. We focus on the applicability of DNA expression analysis to renal disease, especially as some investigators have developed custom serial analysis of gene expression kidney libraries and kidney disease-specific 'designer chip' microarrays. Data analysis techniques and statistics are also discussed, since the challenge is generation of accurate messenger RNA profiles and interpretation of data in a manner that is both coherent and reproducible. SUMMARY Because kidney disease pathophysiology is complex, expression analysis can identify candidate nephropathy pathogenesis genes and gene networks, which eventually could become targets for therapeutic intervention.
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Affiliation(s)
- Patrick S Hayden
- Departments of Medicine and Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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35
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36
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May P, Bock HH, Herz J. Integration of Endocytosis and Signal Transduction by Lipoprotein Receptors. Sci Signal 2003. [DOI: 10.1126/scisignal.1762003pe12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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May P, Bock HH, Herz J. Integration of endocytosis and signal transduction by lipoprotein receptors. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2003; 2003:PE12. [PMID: 12671190 DOI: 10.1126/stke.2003.176.pe12] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The members of the low density lipoprotein receptor (LDLR) gene family are cell surface molecules with diverse functions in cellular metabolism. All LDLR family members are endocytic receptors that mediate the uptake of extracellular cargo into the cell; recent research indicates that they also participate directly in signal transduction. Regulated proteolytic release of the intracellular domain of one of these lipoprotein receptors, the LDLR-related protein 1 (LRP1), has been described, along with the possible role of the released domain in transcriptional regulation. A recent study suggests that megalin, a member of the LDLR gene family that mediates the cellular uptake of vitamin D carrier protein, may also modulate vitamin D-related gene transcription through sequestration of a component of the vitamin D receptor transcriptional complex. May et al. discuss this research in the context of the integration of endocytosis and signaling by this receptor family.
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Affiliation(s)
- Petra May
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
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Leheste JR, Melsen F, Wellner M, Jansen P, Schlichting U, Renner-Müller I, Andreassen TT, Wolf E, Bachmann S, Nykjaer A, Willnow TE. Hypocalcemia and osteopathy in mice with kidney-specific megalin gene defect. FASEB J 2003; 17:247-9. [PMID: 12475886 DOI: 10.1096/fj.02-0578fje] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Megalin is an endocytic receptor highly expressed in the proximal tubules of the kidney. Recently, we demonstrated that this receptor is essential for the renal uptake and conversion of 25-OH vitamin D3 to 1,25-(OH)2 vitamin D3, a central step in vitamin D and bone metabolism. Unfortunately, the perinatal lethality of the conventional megalin knockout mouse model precluded the detailed analysis of the significance of megalin for calcium homeostasis and bone turnover in vivo. Here, we have generated a new mouse model with conditional inactivation of the megalin gene in the kidney by using Cre recombinase. Animals with a renal-specific receptor gene defect were viable and fertile. However, lack of receptor expression in the kidney results in plasma vitamin D deficiency, in hypocalcemia and in severe bone disease, characterized by a decrease in bone mineral content, an increase in osteoid surfaces, and a lack of mineralizing activity. These features are consistent with osteomalacia (softening of the bones) as a consequence of hypovitaminosis D and demonstrate the crucial importance of the megalin pathway for systemic calcium homeostasis and bone metabolism.
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Affiliation(s)
- Jörg R Leheste
- Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
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Petersen HH, Hilpert J, Militz D, Zandler V, Jacobsen C, Roebroek AJM, Willnow TE. Functional interaction of megalin with the megalinbinding protein (MegBP), a novel tetratrico peptide repeat-containing adaptor molecule. J Cell Sci 2003; 116:453-61. [PMID: 12508107 DOI: 10.1242/jcs.00243] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Megalin is a member of the LDL receptor gene family that plays an important role in forebrain development and in cellular vitamin D metabolism through endocytic uptake of vitamin D metabolites. Similar to other receptors in this gene family, megalin is believed to functionally interact with intracellular proteins through adaptors that bind to the receptor tail and regulate its endocytic and signal transducing activities. Using yeast two-hybrid screens, we identified a novel scaffold protein with tetratrico peptide repeats, the megalin-binding protein (MegBP) that associates with the receptor. The binding site of MegBP was mapped to an N-terminal region on the receptor tail harboring a proline-rich peptide element. MegBP binding did not block the endocytic activity of the receptor; however, overexpression resulted in cellular lethality. In further screens, we identified proteins that bound to MegBP and thus might be recruited to the megalin tail. MegBP-interacting partners included several transcriptional regulators such as the SKI-interacting protein (SKIP), a co-activator of the vitamin D receptor. These finding suggest a model whereby megalin directly participates in transcriptional regulation through controlled sequestration or release of transcription factors via MegBP.
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Affiliation(s)
- Helle Heibroch Petersen
- Max-Delbrueck-Center for Molecular Medicine and Medical Faculty of the Free University of Berlin, Germany
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