401
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Eller P, Hochegger K, Wehinger A, Tancevski I, Schgoer W, Ritsch A, Patsch JR. Hepatic ENPP1 expression is induced in diabetic rabbits. Mamm Genome 2006; 17:886-91. [PMID: 16897338 DOI: 10.1007/s00335-006-0028-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 03/31/2006] [Indexed: 11/28/2022]
Abstract
The ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is an inhibitor of the insulin receptor. Variants of ENPP1 are associated with infantile arterial calcification, obesity, and insulin resistance. To study the functional relevance of this protein in vivo, we cloned rabbit ENPP1 and studied its regulation in experimentally induced diabetes mellitus. We amplified and sequenced the complete coding sequence of rabbit ENPP1 gene out of a liver cDNA library using redundant primers deduced from other species. Next, we performed quantitative PCR of ENPP1 to study the tissue distribution of ENPP1 expression and its regulation in an alloxan-dependent diabetes model. The putative rabbit ENPP1 protein contains 873 amino acids and is highly conserved when compared with human ENPP1 (90% amino acid identity). Particularly high levels of ENPP1 mRNA expression were found in adipose tissue. Quantitative PCR analysis revealed a significant upregulation of ENPP1 transcription in liver (p = 0.025) and brain (p = 0.034) of diabetic rabbits compared with controls. Hepatic ENPP1 expression is induced in diabetic rabbits when compared with controls. This approximately twofold upregulation of ENPP1 mRNA in rabbit liver parallels previous findings in patients with type 2 diabetes mellitus. We provide further molecular information about ENPP1 as a potential pharmacologic target and characterize its regulation in an insulin-dependent diabetes mellitus animal model.
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Affiliation(s)
- Philipp Eller
- Department of Internal Medicine, Division of General Internal Medicine, Medical University Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
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402
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Lemire JM, Patis C, Gordon LB, Sandy JD, Toole BP, Weiss AS. Aggrecan expression is substantially and abnormally upregulated in Hutchinson–Gilford Progeria Syndrome dermal fibroblasts. Mech Ageing Dev 2006; 127:660-9. [PMID: 16650460 DOI: 10.1016/j.mad.2006.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 03/10/2006] [Accepted: 03/13/2006] [Indexed: 12/21/2022]
Abstract
Hutchinson-Gilford Progeria syndrome (HGPS) is a rare genetic disorder that displays features of segmental aging. It is manifested predominantly in connective tissue, with most prominent histological changes occurring in the skin, cartilage, bone and cardiovascular tissues. Detailed quantitative real time reverse-transcription polymerase chain reaction studies confirmed the previous observation that platelet-derived growth factor A-chain transcripts are consistently elevated 11+/-2- to 13+/-2-fold in two HGPS dermal fibroblast lines compared with age-matched controls. Furthermore, we identified two additional genes with substantially altered transcript levels. Nucleotide pyrophosphatase transcription was virtually shut down with decreased expression of 13+/-3- to 59+/-3-fold in HGPS, whereas aggrecan mRNA was elevated to 24+/-5 times to 41+/-4 times that of chronologically age-matched controls. Aggrecan, normally a component of cartilage and not always detectable in normal fibroblasts cultures, was secreted by HGPS fibroblast lines and was produced as a proteoglycan. This demonstrates that elevated aggrecan expression and its secretion are aberrant features of HGPS. We conclude that HGPS cells can display massively altered transcript levels leading to the secretion of inappropriate protein species.
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Affiliation(s)
- Joan M Lemire
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA, USA
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403
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Gurley KA, Chen H, Guenther C, Nguyen ET, Rountree RB, Schoor M, Kingsley DM. Mineral formation in joints caused by complete or joint-specific loss of ANK function. J Bone Miner Res 2006; 21:1238-47. [PMID: 16869722 DOI: 10.1359/jbmr.060515] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED To reveal the ANK complete loss of function phenotype in mice, we generated conditional and null alleles. Mice homozygous for the null allele exhibited widespread joint mineralization, similar in severity to animals harboring the original ank allele. A delayed yet similar phenotype was observed in mice with joint-specific loss of ANK function. INTRODUCTION The ANK pyrophosphate regulator was originally identified and proposed to play a key role in articular cartilage maintenance based on a single spontaneous mouse mutation (ank) that causes severe generalized arthritis. A number of human mutations have subsequently been reported in the human ortholog (ANKH), some of which produce skull and long bone defects with no apparent defects in joints or articular cartilage. None of the currently known mouse or human mutations clearly eliminate the function of the endogenous gene. MATERIALS AND METHODS Two new Ank alleles were generated using homologous recombination in mouse embryonic stem (ES) cells. Joint range of motion assays and muCT studies were used to quantitatively assess phenotypic severity in wildtype, heterozygous, and homozygous mice carrying either the null (Anknull) or original (Ankank) allele. A Gdf5-Cre expressing line was crossed to mice harboring the conditional (Ankfloxp) allele to eliminate ANK function specifically in the joints. Histological stains and beta-galactosidase (LACZ) activity were used to determine the correlation between local loss of ANK function and defective joint phenotypes. RESULTS Anknull/Anknull mice develop severe ectopic postnatal crystal deposition in almost every joint of the body, leading to eventual joint fusion and loss of mobility. The severity of phenotype in these mice is indistinguishable from that of Ankank/Ankank mice. In addition, despite the widespread expression of Ank in many tissues, the specific deletion of Ank in joints also produces joint mineralization and ankylosis. CONCLUSIONS These studies show that ANK function is required locally in joints to inhibit mineral formation and that the Ank gene plays a key role in postnatal maintenance of joint mobility and function.
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Affiliation(s)
- Kyle A Gurley
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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404
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Abstract
PURPOSE OF REVIEW Physiological mineralization is necessary for the formation of skeletal tissues and for their appropriate functions during adulthood. Pathological or ectopic mineralization of soft tissues, including articular cartilage and cardiovascular tissues, leads to morbidity and mortality. Recent findings suggest that the mechanisms and factors regulating physiological mineralization may be identical or similar to those regulating ectopic mineralization. Therefore, the purpose of this review is to describe the current knowledge of mechanisms and determinants that regulate physiological mineralization and how these determinants can be used to understand ectopic mineralization better. RECENT FINDINGS Recent findings have indicated that physiological and pathological mineralization are initiated by matrix vesicles, membrane-enclosed particles released from the plasma membrane of mineralization-competent cells. An understanding of how these vesicles initiate the physiological mineralization process may provide novel therapeutic strategies to prevent ectopic mineralization. In addition, other regulators (activators and inhibitors) of physiological mineralization have been identified and characterized, and evidence indicates that the same factors also contribute to the regulation of ectopic mineralization. Finally, programmed cell death (apoptosis) may be a contributor to physiological mineralization, and if occurring after tissue injury may induce ectopic mineralization and mineralization-related differentiation events in the injured area and surrounding areas. SUMMARY This review describes how the understanding of mechanisms and factors regulating physiological mineralization can be used to develop new therapeutic strategies to prevent pathological or ectopic mineralization events.
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Affiliation(s)
- Thorsten Kirsch
- Musculoskeletal Research Laboratories, Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
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405
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Physiologic and pathologic functions of the NPP nucleotide pyrophosphatase/phosphodiesterase family focusing on NPP1 in calcification. Purinergic Signal 2006; 2:371-7. [PMID: 18404477 PMCID: PMC2254483 DOI: 10.1007/s11302-005-5304-3] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 11/11/2005] [Accepted: 11/14/2005] [Indexed: 02/07/2023] Open
Abstract
The catabolism of ATP and other nucleotides participates partly in the important function of nucleotide salvage by activated cells and also in removal or de novo generation of compounds including ATP, ADP, and adenosine that stimulate purinergic signaling. Seven nucleotide pyrophosphatase/phosphodiesterase NPP family members have been identified to date. These isoenzymes, related by up conservation of catalytic domains and certain other modular domains, exert generally non-redundant functions via distinctions in substrates and/or cellular localization. But they share the capacity to hydrolyze phosphodiester or pyrophosphate bonds, though generally acting on distinct substrates that include nucleoside triphosphates, lysophospholipids and choline phosphate esters. PPi generation from nucleoside triphosphates, catalyzed by NPP1 in tissues including cartilage, bone, and artery media smooth muscle cells, supports normal tissue extracellular PPi levels. Balance in PPi generation relative to PPi degradation by pyrophosphatases holds extracellular PPi levels in check. Moreover, physiologic levels of extracellular PPi suppress hydroxyapatite crystal growth, but concurrently providing a reservoir for generation of pro-mineralizing Pi. Extracellular PPi levels must be supported by cells in mineralization-competent tissues to prevent pathologic calcification. This support mechanism becomes dysregulated in aging cartilage, where extracellular PPi excess, mediated in part by upregulated NPP1 expression stimulates calcification. PPi generated by NPP1modulates not only hydroxyapatite crystal growth but also chondrogenesis and expression of the mineralization regulator osteopontin. This review pays particular attention to the role of NPP1-catalyzed PPi generation in the pathogenesis of certain disorders associated with pathologic calcification.
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406
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Stefan C, Jansen S, Bollen M. Modulation of purinergic signaling by NPP-type ectophosphodiesterases. Purinergic Signal 2006; 2:361-70. [PMID: 18404476 PMCID: PMC2254485 DOI: 10.1007/s11302-005-5303-4] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 11/11/2005] [Accepted: 11/11/2005] [Indexed: 12/17/2022] Open
Abstract
Extracellular nucleotides can elicit a wide array of cellular responses by binding to specific purinergic receptors. The level of ectonucleotides is dynamically controlled by their release from cells, synthesis by ectonucleoside diphosphokinases and ectoadenylate kinases, and hydrolysis by ectonucleotidases. One of the four structurally unrelated families of ectonucleotidases is represented by the NPP-type ectophosphodiesterases. Three of the seven members of the NPP family, namely NPP1–3, are known to hydrolyze nucleotides. The enzymatic action of NPP1–3 (in)directly results in the termination of nucleotide signaling, the salvage of nucleotides and/or the generation of new messengers like ADP, adenosine or pyrophosphate. NPP2 is unique in that it hydrolyzes both nucleotides and lysophospholipids and, thereby, generates products that could synergistically promote cell motility. We review here the enzymatic properties of NPPs and analyze current evidence that links their nucleotide-hydrolyzing capability to epithelial and neural functions, the immune response and cell motility.
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Affiliation(s)
- Cristiana Stefan
- Division of Biochemistry, Department of Molecular Cell Biology, Faculty of Medicine, KULeuven, B-3000, Leuven, Belgium,
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407
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McKee MD, Addison WN, Kaartinen MT. Hierarchies of Extracellular Matrix and Mineral Organization in Bone of the Craniofacial Complex and Skeleton. Cells Tissues Organs 2006; 181:176-88. [PMID: 16612083 DOI: 10.1159/000091379] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Structural hierarchies are common in biologic systems and are particularly evident in biomineralized structures. In the craniofacial complex and skeleton of vertebrates, extracellular matrix and mineral of bone are structurally ordered at many dimensional scales from the macro level to the nano level. Indeed, the nanocomposite texture of bone, with nanocrystals of apatitic mineral embedded within a crosslinked matrix of fibrillar and nonfibrillar proteins, imparts to bone the very mechanical properties and toughness it needs to function in vital organ protection, musculoskeletal movement and mastication. This article focuses on how hierarchies of extracellular matrix protein organization influence bone cell behavior, tissue architecture and mineralization. Additional attention is given to recent work on the molecular determinants of mineral induction in bone, and how the mineralization process is subsequently regulated by inhibitory proteins.
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Affiliation(s)
- M D McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada.
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408
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Ketteler M, Schlieper G, Floege J. Calcification and cardiovascular health: new insights into an old phenomenon. Hypertension 2006; 47:1027-34. [PMID: 16618842 DOI: 10.1161/01.hyp.0000219635.51844.da] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Markus Ketteler
- Department of Nephrology and Clinical Immunology, University Hospital Aachen, Germany.
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409
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Horikoshi T, Maeda K, Kawaguchi Y, Chiba K, Mori K, Koshizuka Y, Hirabayashi S, Sugimori K, Matsumoto M, Kawaguchi H, Takahashi M, Inoue H, Kimura T, Matsusue Y, Inoue I, Baba H, Nakamura K, Ikegawa S. A large-scale genetic association study of ossification of the posterior longitudinal ligament of the spine. Hum Genet 2006; 119:611-6. [PMID: 16609882 DOI: 10.1007/s00439-006-0170-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 03/14/2006] [Indexed: 10/24/2022]
Abstract
Research to date has identified several genes that are implicated in the etiology of ossification of the posterior longitudinal ligament of the spine (OPLL); however, their pathogenetic relevance remains obscure. The aim of this study is to identify susceptibility genes for OPLL through a large-scale case-control association study and to re-examine previously reported associations. A total of 109 single nucleotide polymorphisms (SNPs) in 35 candidate genes were genotyped for 711 sporadic OPLL patients and 896 controls. The differences in allelic and genotypic distribution between patients and controls were assessed using the chi (2) test with Bonferroni's correction. We also analyzed the association by separating patients into subgroups according to sex, age and the number of ossified vertebrae. The nominal P values fell below 0.05 for five SNPs in three genes. An intronic SNP in the TGF3 gene (P=0.00040) showed the most significant association. Previously reported associations of COL11A2, NPPS and TGFB1 with OPLL could not be reproduced. Further, no significant associations were detected in stratified analyses based on sex, age or the number of ossified vertebrae. TGFB3 warrants further investigation because it is located within a genomic region that has been positively linked with OPLL.
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Affiliation(s)
- Taizo Horikoshi
- Laboratory for Bone and Joint Diseases, SNP Research Center, RIKEN, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan
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410
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Ciana G, Trappan A, Bembi B, Benettoni A, Maso G, Zennaro F, Ruf N, Schnabel D, Rutsch F. Generalized arterial calcification of infancy: two siblings with prolonged survival. Eur J Pediatr 2006; 165:258-63. [PMID: 16315058 DOI: 10.1007/s00431-005-0035-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 09/12/2005] [Accepted: 09/18/2005] [Indexed: 01/31/2023]
Abstract
In generalized arterial calcification of infancy (OMIM no. 208000), calcification of the media and proliferation of the intima lead to arterial stenoses. Most affected patients present with untreatable arterial hypertension and die within the first months of life. The disease has recently been linked to mutations in ENPP1. We report two siblings with prolonged survival, both of whom carry the compound heterozygous ENPP1 mutations c.913C>A and c.1164+2T>A. In both siblings, spontaneous regression of arterial calcifications occurred, and antihypertensive treatment could be tapered off gradually. In some patients, the natural course of GACI may be more favourable than previously assumed.
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MESH Headings
- Aorta, Abdominal
- Aortic Diseases/diagnosis
- Aortic Diseases/genetics
- Arterial Occlusive Diseases/diagnosis
- Arterial Occlusive Diseases/genetics
- Calcinosis/diagnosis
- Calcinosis/genetics
- Cardiomyopathies/diagnosis
- Cardiomyopathies/genetics
- Child
- Child, Preschool
- Chromosome Aberrations
- Echocardiography
- Female
- Follow-Up Studies
- Genes, Recessive
- Heart Failure/diagnosis
- Heart Failure/genetics
- Humans
- Hypophosphatemia, Familial/diagnosis
- Hypophosphatemia, Familial/genetics
- Infant, Newborn
- Mutation, Missense
- Phosphoric Diester Hydrolases/genetics
- Pregnancy
- Prenatal Diagnosis
- Pyrophosphatases/genetics
- Remission, Spontaneous
- Sequence Analysis, DNA
- Survivors
- Ultrasonography, Doppler
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Affiliation(s)
- Giovanni Ciana
- S.C. di Neonatologia e Terapia Intensiva Neonatale, Istituto per l'Infanzia Burlo Garofolo, Via dell'Istria 65/1-34100, Trieste, Italy
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411
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Glatz AC, Pawel BR, Hsu DT, Weinberg P, Chrisant MRK. Idiopathic infantile arterial calcification: two case reports, a review of the literature and a role for cardiac transplantation. Pediatr Transplant 2006; 10:225-33. [PMID: 16573612 DOI: 10.1111/j.1399-3046.2005.00414.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Idiopathic infantile arterial calcification (IIAC) is a rare, but important, cause of rapidly progressive ischemic heart disease in children. In this paper, we report two recent cases of IIAC seen at tertiary referral hospitals. Both cases presented in infancy with signs of heart failure and, ultimately, died with the diagnosis of IIAC confirmed at postmortem examination. A thorough review of the literature reveals approximately 160 reported cases of IIAC. The clinical outcomes, radiographic findings and pathologic details are summarized. Proposed etiologic mechanisms are reviewed, including promising research into the role of inorganic pyrophosphate as a regulatory factor in the development of IIAC. Because of the typically fatal outcome of IIAC and the lack of proven therapies, the potential role for cardiac transplantation is discussed.
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Affiliation(s)
- Andrew C Glatz
- Division of Cardiology, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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412
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Ruf N, Dünzinger U, Brinckmann A, Haaf T, Nürnberg P, Zechner U. Expression profiling of uniparental mouse embryos is inefficient in identifying novel imprinted genes. Genomics 2006; 87:509-19. [PMID: 16455231 DOI: 10.1016/j.ygeno.2005.12.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 12/15/2005] [Accepted: 12/15/2005] [Indexed: 12/23/2022]
Abstract
Imprinted genes are expressed from only one allele in a parent-of-origin-specific manner. We here describe a systematic approach to identify novel imprinted genes using quantification of allele-specific expression by Pyrosequencing, a highly accurate method to detect allele-specific expression differences. Sixty-eight candidate imprinted transcripts mapping to known imprinted chromosomal regions were selected from a recent expression profiling study of uniparental mouse embryos and analyzed. Three novel imprinted transcripts encoding putative non-protein-coding RNAs were identified on the basis of parent-of-origin-specific monoallelic expression in E11.5 (C57BL/6 x Cast/Ei)F1 and informative (C57BL/6 x Cast/Ei) x C57BL/6 backcross embryos. In addition, four transcripts with preferential expression of a strain-specific allele were found. Intriguingly, a vast majority of the analyzed transcripts showed no imprinting-associated expression in F1 embryos. These data strengthen the view that a large fraction of nonimprinted genes is differentially expressed between parthenogenetic and androgenetic embryos and question the efficiency of expression profiling of uniparental embryos to identify novel imprinted genes.
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MESH Headings
- Alleles
- Animals
- Chromosome Mapping
- Chromosomes
- Crosses, Genetic
- DNA/genetics
- DNA/isolation & purification
- DNA, Complementary/genetics
- Databases, Genetic
- Embryo, Mammalian
- Female
- Gene Expression
- Gene Expression Profiling
- Genetic Variation
- Genomic Imprinting
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Models, Genetic
- Parthenogenesis
- Polymorphism, Single Nucleotide
- Prader-Willi Syndrome/genetics
- Pregnancy
- RNA/isolation & purification
- RNA, Messenger/genetics
- Software
- Transcription, Genetic
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Affiliation(s)
- Nico Ruf
- Max-Delbrueck-Center for Molecular Medicine, Berlin-Buch, Germany
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413
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Ketteler M, Westenfeld R, Schlieper G, Brandenburg V. Pathogenesis of vascular calcification in dialysis patients. Clin Exp Nephrol 2006; 9:265-270. [PMID: 16362152 DOI: 10.1007/s10157-005-0385-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Accepted: 09/12/2005] [Indexed: 01/15/2023]
Abstract
Soft-tissue and vascular calcification are highly prevalent in end-stage renal disease (ESRD). Vascular calcifications manifest as both medial and intimal calcification of arteries and are a hallmark of the accelerated atherosclerosis observed in uremia. The nature of vascular calcification is progressive, and is associated with arterial stiffness and increased cardiovascular mortality. Age, duration of dialysis, and diabetes mellitus are clear determinants of the severity of vascular calcification; however, more recently novel insights into the pathomechanisms of unwanted calcification processes have been gained. Disturbances of mineral metabolism such as hyperphosphatemia and hypercalcemia appear to contribute to progressive calcification, not only by passive precipitation but by actively inducing changes in vascular smooth muscle cell behavior toward an osteoblast-like phenotype. Specific calcium-regulatory proteins may act locally or systemically as calcification inhibitors. Dysregulations of calcification inhibitors, including fetuin-A, matrix Gla protein, osteoprotegerin, and pyrophosphates may also be pathophysiologically relevant factors in the context of uremic extraosseous calcification. In this context, low serum fetuin-A levels were recently found to be associated with increased mortality in cohorts of dialysis patients. This overview intends to summarize current knowledge of the scientific concepts involved in the pathogenesis of extraosseous calcification in ESRD.
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Affiliation(s)
- Markus Ketteler
- Department of Nephrology and Clinical Immunology, University Hospital Aachen, Pauwelsstrasse 30, D-52057, Aachen, Germany.
| | - Ralf Westenfeld
- Department of Nephrology and Clinical Immunology, University Hospital Aachen, Pauwelsstrasse 30, D-52057, Aachen, Germany
| | - Georg Schlieper
- Department of Nephrology and Clinical Immunology, University Hospital Aachen, Pauwelsstrasse 30, D-52057, Aachen, Germany
| | - Vincent Brandenburg
- Department of Nephrology and Clinical Immunology, University Hospital Aachen, Pauwelsstrasse 30, D-52057, Aachen, Germany
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414
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Numakura C, Yamada M, Ariyasu D, Maesaka A, Kobayashi H, Nishimura G, Ikeda M, Hasegawa Y. Genetic and enzymatic analysis for two Japanese patients with idiopathic infantile arterial calcification. J Bone Miner Metab 2006; 24:48-52. [PMID: 16369898 DOI: 10.1007/s00774-005-0645-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Accepted: 07/15/2005] [Indexed: 11/26/2022]
Abstract
Idiopathic infantile arterial calcification (IIAC) is a life-threatening disorder in young infants. Cardiovascular symptoms are usually apparent within the first month of life. The symptoms are caused by calcification of large and medium-sized arteries, including the aorta, coronary arteries, and renal arteries. Most of the patients die by 6 months of age because of heart failure. Recently, homozygous or compound heterozygous mutations for the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) gene were reported as causative for the disorder. ENPP1 regulates extracellular inorganic pyrophosphate (PPi), a major inhibiter of extracellular matrix calcification. Two Japanese patients with IIAC were studied. One, from first-cousin parents, showed a typical clinical course. The onset in the second patient was late. Both of the patients were clinically compatible for IIAC; arterial calcification was shown, and hypertension was prominent. We sequenced all the exons and exon-intron boundaries of the gene and measured nucleotide pyrophosphohydrolase (NPPH) activity of ENPP1. Homozygous Arg730Stop was detected in the typical IIAC patient. The mutation was a novel nonsense mutation and not detected in 60 healthy controls. His NPPH activity was 4% of normal. On the other hand, the late-onset patient was not shown to have any mutations. NPPH activity in this patient was 70% of normal. We confirmed that ENPP1 was also responsible for the Japanese patient with IIAC. The atypical late-onset phenotype may not be associated with ENPP1 abnormalities. IIAC is considered to be a clinically and genetically heterogeneous disorder.
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Affiliation(s)
- Chikahiko Numakura
- Endocrinology and Metabolism Unit, Tokyo Metropolitan Kiyose Children's Hospital, Kiyose, Japan.
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415
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El-Abbadi M, Giachelli CM. Arteriosclerosis, calcium phosphate deposition and cardiovascular disease in uremia: current concepts at the bench. Curr Opin Nephrol Hypertens 2005; 14:519-24. [PMID: 16205469 DOI: 10.1097/01.mnh.0000168335.29381.23] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Cardiovascular disease is the leading cause of death in patients with chronic kidney disease. A growing body of data points to nontraditional risk factors, including disturbances in mineral metabolism, as important determinants of the extremely high cardiovascular morbidity and mortality rates in these patients. Disturbances in mineral metabolism, especially elevated calcium and phosphate levels, have been linked to vascular and valvular calcification, both of which are associated with poor prognosis in chronic kidney disease patients. This review highlights important recent findings regarding the etiology of vascular calcification, with special emphasis on pathways that may be particularly relevant in chronic kidney disease patients. RECENT FINDINGS New studies indicate that not only vascular intimal calcification (associated with atherosclerosis) but also vascular medial calcification are correlated with decreased survival in chronic kidney disease patients. With the relatively recent recognition of vascular calcification as an actively regulated process, a growing list of inducers (calcium, phosphate, inflammatory cytokines) and inhibitors (matrix Gla protein, fetuin, pyrophosphate, osteopontin) have been discovered. Interesting recent evidence suggests that they may contribute to the prevalence of this pathology in chronic kidney disease patients. SUMMARY Vascular calcification is associated with decreased survival in chronic kidney disease patients. Understanding the causes and regulatory factors controlling vascular calcification will help refine therapeutic modalities currently in use, as well as develop novel therapeutics to abate and potentially reverse this deleterious process.
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Affiliation(s)
- Mohga El-Abbadi
- Bioengineering Department, University of Washington, Seattle, Washington 98195, USA
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416
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London GM, Marchais SJ, Guérin AP, Métivier F. Arteriosclerosis, vascular calcifications and cardiovascular disease in uremia. Curr Opin Nephrol Hypertens 2005; 14:525-31. [PMID: 16205470 DOI: 10.1097/01.mnh.0000168336.67499.c0] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Arterial calcification in chronic kidney disease (CKD) is associated with increased cardiovascular risk. The mechanisms responsible for arterial calcification include alterations of mineral metabolism and expression of mineral-regulating proteins. RECENT FINDINGS Arterial calcification is similar to bone formation, involving differentiation of vascular smooth muscle cells (VSMCs) into phenotypically distinct osteoblast-like cells. Elevated phosphate and/or calcium trigger a concentration-dependent increase of calcium precipitates in VSMC in vitro. The calcification is initiated by VSMC release of membrane-bound matrix vesicles and formation of apoptotic bodies. The presence of serum prevents these changes, indicating the presence of calcification inhibitors. Arterial calcification occurs in two sites: the tunica intima and tunica media. Intimal calcification is a marker of atherosclerotic disease and is associated with arterial stenotic lesions. Medial calcification influences outcome by promoting arterial stiffening whose principal consequences are left-ventricular hypertrophy and altered coronary perfusion. Aortic stiffness is an independent predictor of all-cause and cardiovascular mortality in CKD patients. Age, duration of dialysis, smoking and diabetes are risk factors for the development of arterial calcification in end-stage renal disease. Oversuppression of parathyroid hormone and low bone turnover potentiate the development of arterial calcification. SUMMARY Arterial disease in CKD patients is characterized by extensive calcification. Evidence has accumulated pointing to the active and regulated nature of the calcification process. Elevated phosphate and calcium may stimulate sodium-dependent phosphate cotransport involving osteoblast-like changes in cellular gene expression. Arterial calcification is responsible for stiffening of the arteries with increased left-ventricular afterload and abnormal coronary perfusion as the principal clinical consequences.
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Affiliation(s)
- Gérard M London
- Service d'Hémodialyse, Hôpital F.H. Manhès, 8, rue Roger Clavier, 91712 Fleury-Mérogis, Cedex, France.
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417
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Stefan C, Jansen S, Bollen M. NPP-type ectophosphodiesterases: unity in diversity. Trends Biochem Sci 2005; 30:542-50. [PMID: 16125936 DOI: 10.1016/j.tibs.2005.08.005] [Citation(s) in RCA: 286] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 07/25/2005] [Accepted: 08/15/2005] [Indexed: 02/07/2023]
Abstract
Nucleotide pyrophosphatase/phosphodiesterase (NPP)-type ectophosphodiesterases are found at the cell surface as type-I or type-II transmembrane proteins, but are also found extracellularly as secreted or shedded enzymes. They hydrolyze pyrophosphate or phosphodiester bonds in a variety of extracellular compounds including nucleotides, (lyso)phospholipids and choline phosphate esters. Despite their structurally related catalytic domain, each enzyme has well-defined substrate specificity. Catalysis by NPPs affects processes as diverse as cell proliferation and motility, angiogenesis, bone mineralization and digestion. In addition, there is emerging evidence for non-catalytic functions of NPPs in cell signaling. NPP-type ectophosphodiesterases are also implicated in the pathophysiology of cancer, insulin resistance and calcification diseases, and they hold great promise as easily accessible therapeutic targets.
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Affiliation(s)
- Cristiana Stefan
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
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418
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Towler DA. Inorganic pyrophosphate: a paracrine regulator of vascular calcification and smooth muscle phenotype. Arterioscler Thromb Vasc Biol 2005; 25:651-4. [PMID: 15790939 DOI: 10.1161/01.atv.0000158943.79580.9d] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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419
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Abstract
Vascular calcification is prevalent in aging as well as a number of pathological conditions, and it is now recognized as a strong predictor of cardiovascular events in the general population as well as diabetic and end-stage renal disease patients. Vascular calcification is a highly regulated process involving inductive and inhibitory mechanisms. This article focuses on two molecules, phosphate and osteopontin, that have been implicated in the induction or inhibition of vascular calcification, respectively. Elevated phosphate is of interest because hyperphosphatemia is recognized as a major nonconventional risk factor for cardiovascular disease mortality in end-stage renal disease patients. Studies to date suggest that elevated phosphate stimulates smooth muscle cell phenotypic transition and mineralization via the activity of a sodium-dependent phosphate cotransporter. Osteopontin, however, appears to block vascular calcification most likely by preventing calcium phosphate crystal growth and inducing cellular mineral resorption.
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Affiliation(s)
- Cecilia M Giachelli
- Bioengineering Department, University of Washington, Seattle, Wash 98195, USA.
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420
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Farzaneh-Far A, Shanahan CM. Biology of vascular calcification in renal disease. NEPHRON. EXPERIMENTAL NEPHROLOGY 2005; 101:e134-8. [PMID: 16113585 DOI: 10.1159/000087578] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The high rates of atherosclerotic vascular disease in patients with end-stage renal disease (ESRD) cannot be fully explained by the excess of traditional risk factors. Interest has therefore arisen in the possible role of vascular calcification, which is increased in these patients and may effect plaque stability and have detrimental hemodynamic consequences. Considerable evidence has accumulated recently pointing to the regulated nature of the calcification process. The initiation of calcium crystal formation appears to require the presence of small membrane bound vesicles released by living or apoptotic cells. The cellular release, content and phagocytosis of these vesicles appear to be important regulatory pathways in vascular calcification. Better understanding of these mechanisms may have therapeutic potential in reducing the adverse cardiovascular event rates in patients with (ESRD).
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Affiliation(s)
- Afshin Farzaneh-Far
- Division of Cardiology, New York Presbyterian Hospital, Cornell University Medical Center, New York, NY, USA
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421
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Abstract
A genetic association of the ENPP1 gene with primary hand osteoarthritis was recently reported in this journal. ENPP1 encodes an enzyme that regulates soft tissue calcification. The study as it stands is far from complete because the actual causal variant(s) within ENPP1 has not been identified and no functional study on the activity of the enzyme in hand osteoarthritis was presented. Nevertheless, the study stimulates interest and will encourage others in the field to test ENPP1 as a possible osteoarthritis susceptibility gene in their cohorts. The genetic basis of osteoarthritis is slowly being uncovered, and this report constitutes another interesting find.
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Affiliation(s)
- John Loughlin
- University of Oxford, Institute of Musculoskeletal Sciences, Botnar Research Centre, Oxford, UK.
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422
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Suk EK, Malkin I, Dahm S, Kalichman L, Ruf N, Kobyliansky E, Toliat M, Rutsch F, Nürnberg P, Livshits G. Association of ENPP1 gene polymorphisms with hand osteoarthritis in a Chuvasha population. Arthritis Res Ther 2005; 7:R1082-90. [PMID: 16207325 PMCID: PMC1257435 DOI: 10.1186/ar1786] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 05/31/2005] [Accepted: 06/14/2005] [Indexed: 02/04/2023] Open
Abstract
Periarticular calcification is a common attendant symptom of generalized arterial calcification of infancy, a rare Mendelian disorder caused by mutations of the gene coding for ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). This prompted us to perform a family-based association study to test the hypothesis that genetic variation at the ENPP1 locus is involved in the etiology of osteoarthritis of the hand. The study population comprised 126 nuclear families with 574 adult individuals living in small villages in the Chuvasha and Bashkirostan autonomies of the Russian Federation. The extent of osteoarthritis was determined by analyzing plain hand radiographs. The outcome of a principal component analysis of osteoarthritis scores of a total of 28 joints of both hands was used as a primary phenotype in this study. Maximum likelihood estimates of the variance component analysis revealed a substantial contribution of genetic factors to the overall trait variance of about 25% in this homogeneous population. Three short tandem repeat (STR) polymorphisms – one intragenic and two flanking markers – and four single-nucleotide polymorphisms were tested. The markers tagged the ENPP1 locus at nearly equal intervals. We used three different transmission disequilibrium tests and obtained highly significant association signals. Alleles of the upstream microsatellite marker as well as several single-nucleotide polymorphism haplotypes consistently revealed the association. Thus, our data highlights variability of ENPP1 as an important genetic factor in the pathogenesis of idiopathic osteoarthritis.
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Affiliation(s)
- Eun-Kyung Suk
- Gene Mapping Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ida Malkin
- Human Population Biology, Research Unit, Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - Stefan Dahm
- Bioinformatics Section, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Leonid Kalichman
- Human Population Biology, Research Unit, Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - Nico Ruf
- Gene Mapping Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Eugene Kobyliansky
- Human Population Biology, Research Unit, Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - Mohammad Toliat
- Gene Mapping Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Cologne Center for Genomics and Institute for Genetics, University of Cologne, Germany
| | - Frank Rutsch
- Department of Pediatrics, University Medical School Münster, Germany
| | - Peter Nürnberg
- Gene Mapping Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Institute of Medical Genetics, Charité – University Hospitals of Berlin, Germany
- Cologne Center for Genomics and Institute for Genetics, University of Cologne, Germany
| | - Gregory Livshits
- Human Population Biology, Research Unit, Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
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423
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Abstract
PURPOSE OF REVIEW Accumulating evidence suggests that the high cardiovascular mortality observed in patients with end-stage renal disease is due in part to the deleterious effects of vascular calcification that develops over time on dialysis. This review focuses on recent cell biological and animal studies that have shed light on the mechanisms and regulators of vascular smooth muscle cell calcification in end-stage renal disease. RECENT FINDINGS Clinical studies demonstrate that high circulating levels of phosphate or calcium predict vascular calcification. Recent cell biological studies have provided novel insights into how vascular smooth muscle cells regulate calcification in response to such insults. Vascular smooth muscle cell damage and subsequent vesicle release from viable and dying cells create an environment permissive for the nucleation of basic calcium phosphate mineral. This, combined with osteogenic conversion of vascular smooth muscle cells and consequent loss of their normal inhibitory processes/pathways, results in calcification. Circulating factors such as fetuin-A, with the potential to impact on vessel wall calcification, have also been identified. Animal studies suggest that the 'uremic milieu' potentiates calcification and have clearly established a link between vascular calcification and bone metabolism. However, our understanding of the factors that contribute to vascular smooth muscle cell calcification in end-stage renal disease remains incomplete. SUMMARY Systematic studies are required that integrate epidemiological studies to identify risk factors with in-vitro experiments to investigate mechanisms leading to vascular smooth muscle cell calcification in response to these factors. Animal and clinical studies can subsequently be used to assess how modifying risk factors under the complex physiological conditions of end-stage renal disease impacts on vessel wall health.
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424
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Abstract
Extraosseus calcification has plagued management of renal failure since the beginning of hemodialysis, but the issue has largely been neglected because the impact on survival was thought to be limited. The recent recognition that hyperphosphatemia is a strong predictor of all-cause mortality, and particularly of cardiac mortality, has transformed the situation. Relatively stringent, though difficult to implement, guidelines have been proposed for the management of hyperphosphatemia. Important recent insights document that, for different reasons, both high and low turnover of bone disease increase the risk of vascular calcifications. Vascular calcification impacts cardiac death not only by complicating coronary atherosclerosis, but also by increasing the stiffness of central arteries, impacting on heart function (increased impedance, reduced coronary perfusion). While in the past extraosseous calcification, including vascular calcification, was thought to be a passive process resulting from transgression of a critical Ca x P product, recent studies show that the adverse effect of hyperphosphatemia is also mediated by active processes (e.g., induction of "osteogenic" genetic programs), and is modulated by calcification inhibitors.
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Affiliation(s)
- Markus Ketteler
- University Hospital Aachen, and Ruperto-Carola University, Heidelberg, Germany.
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425
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Abstract
PURPOSE OF REVIEW Our understanding of the causation of the chondrocalcinosis and other disorders characterized by ectopic mineralization is rapidly increasing, and genetic studies have contributed substantially to recent major advances in the field. This review will discuss what is known about the genetics of chondrocalcinosis and what we have learned from genetic studies to date. RECENT FINDINGS Chondrocalcinosis is one of a family of conditions associated with ectopic mineralization. This family also includes disorders of mineralization of bone and spinal and other ligaments, and vascular calcification. There has been increasing evidence of the key role of transport and metabolism of inorganic pyrophosphate (PPi) in control of mineralization, and as the likely explanation for the association of a variety of genetic variants with chondrocalcinosis and ectopic mineralization elsewhere. This may be an overly simplistic view of this family of conditions, with recent evidence suggesting that, for example, ANKH variants may not all predispose to chondrocalcinosis by effects on PPi transport, but may also influence chondrocyte maturation. SUMMARY Understanding the control of the process of mineralization and its tissue specificity are important steps in the search for rational therapies for these conditions.
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Affiliation(s)
- Yun Zhang
- Institute of Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Nuffield Orthopaedic Centre, Headington, Oxford, UK
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426
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Rutsch F, Terkeltaub R. Deficiencies of physiologic calcification inhibitors and low-grade inflammation in arterial calcification: lessons for cartilage calcification. Joint Bone Spine 2005; 72:110-8. [PMID: 15797489 DOI: 10.1016/j.jbspin.2004.05.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Accepted: 05/10/2004] [Indexed: 11/28/2022]
Abstract
Apart from clinical parallels, similarities in the pathogenesis of arterial and articular cartilage calcification have come to light in recent years. These include the roles of aging, of chronic low-grade inflammation and of genetic and acquired dysregulation of inorganic pyrophosphate (PP(i)) metabolism. This review focuses on recent developments in understanding the pathogenesis of artery calcification pertinent to interpretation of the mechanistic basis for articular cartilage calcification in aging and osteoarthritis.
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Affiliation(s)
- Frank Rutsch
- Klinik und Poliklinik für Kinder- und Jugendmedizin, Universitätsklinikum Münster, Albert-Schweitzer-Strasse 33, D-48149 Münster, Germany.
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427
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Ketteler M, Westenfeld R, Schlieper G, Brandenburg V, Floege J. "Missing" inhibitors of calcification: general aspects and implications in renal failure. Pediatr Nephrol 2005; 20:383-8. [PMID: 15549415 DOI: 10.1007/s00467-004-1614-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Revised: 07/02/2004] [Accepted: 07/08/2004] [Indexed: 11/24/2022]
Abstract
In the recent past, it has become increasingly clear that extracellular calcium and phosphate homeostasis is a tightly regulated process. Since the physiological serum concentrations of calcium and phosphate are several orders of magnitude above their solubility product, mechanisms inhibiting precipitation must be operative to prevent extraosseous calcification. A number of local and systemic calcification inhibitors, including fetuin-A, matrix Gla protein, and osteoprotegerin, have been identified in recent years. Deficiency and dysregulation of such factors may contribute to morbidity and even mortality. Extraosseous calcifications occur with high prevalence in patients with end-stage renal disease. In particular, vascular manifestations are clearly associated with cardiovascular events and decreased survival. In addition to the well-established roles of hyperphosphatemia and an increased calcium x phosphate product, the biological and potential clinical roles of disturbances in calcification inhibition in uremia are discussed in this overview.
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Affiliation(s)
- Markus Ketteler
- Department of Nephrology and Clinical Immunology, University Hospital Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany.
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428
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Goldsmith D, Ritz E, Covic A. Vascular calcification: a stiff challenge for the nephrologist: does preventing bone disease cause arterial disease? Kidney Int 2005; 66:1315-33. [PMID: 15458425 DOI: 10.1111/j.1523-1755.2004.00895.x] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
There has been an explosion of interest in vascular calcification in the last 5 years. Four key "germinal" findings have fallen onto very fertile soil. First, on the background of an increasing cardiovascular disease burden it has been found that at least cross-sectionally, and in a limited fashion prospectively, achieved dialysis plasma phosphate levels are linked to all-cause and cardiovascular mortality. Second, there are increasing reports of calcific uremic arteriolopathy in Australia and the United States. Third, we know know that the mechanical properties of the carotid artery, and the aorta, have a profound influence on survival for dialysis patients. Vascular calcification itself (as assessed by x-ray films and ultrasound) has been linked to aortic stiffness. Fourth, increasing numbers of studies are showing extremely extensive coronary artery calcification (CAC) in dialysis patients, even at a young age. From these apparently unlinked observations the following assertion has been posited-that in the widespread (over) use of calcium-containing oral phosphate binders (OPB) to prevent uremic osteodystrophy in our dialysis population we have unwittingly accelerated widespread uremic vasculopathy and thereby contributed to premature cardiovascular mortality. It is the purpose of this article to discuss vascular calcification (and particularly CAC) in dialysis patients as we understand it today. We will review the published series, with special reference to the Sevelamer Treat to Goal trial and also discuss the new Kidney Disease Outcome Quality Initiative (K-DOQI) guidelines on the use of phosphate binders in chronic kidney disease.
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429
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Dong H, Maddux BA, Altomonte J, Meseck M, Accili D, Terkeltaub R, Johnson K, Youngren JF, Goldfine ID. Increased hepatic levels of the insulin receptor inhibitor, PC-1/NPP1, induce insulin resistance and glucose intolerance. Diabetes 2005; 54:367-72. [PMID: 15677494 DOI: 10.2337/diabetes.54.2.367] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The ectoenzyme, plasma cell membrane glycoprotein-1 (PC-1), is an insulin receptor (IR) inhibitor that is elevated in cells and tissues of insulin-resistant humans. However, the effects of PC-1 overexpression on insulin action have not been studied in animal models. To produce mice with overexpression of PC-1 in liver, a key glucose regulatory organ in this species, we injected them with a PC-1 adenovirus vector that expresses human PC-1. Compared with controls, these mice had two- to threefold elevations of PC-1 content in liver but no changes in other tissues such as skeletal muscle. In liver of PC-1 animals, insulin-stimulated IR tyrosine kinase and Akt/protein kinase B activation were both decreased. In this tissue, the IR-dependent nuclear factor Foxo1 was increased along with two key gluconeogenic enzymes, glucose-6-phosphatase and phosphenolpyruvate carboxykinase. The PC-1 animals had 30-40 mg/dl higher glucose levels and twofold higher insulin levels. During glucose tolerance tests, these animals had peak glucose levels that were >100 mg/dl higher than those of controls. These in vivo data support the concept, therefore, that PC-1 plays a role in insulin resistance and suggest that animals with overexpression of human PC-1 in liver may be interesting models to investigate this pathological process.
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Affiliation(s)
- Hengjiang Dong
- Department of Gene Therapy and Molecular Medicine, Mount Sinai School of Medicine, New York, New York, USA
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430
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Cheng KS, Chen MR, Ruf N, Lin SP, Rutsch F. Generalized arterial calcification of infancy: Different clinical courses in two affected siblings. Am J Med Genet A 2005; 136:210-3. [PMID: 15940697 DOI: 10.1002/ajmg.a.30800] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Generalized arterial calcification of infancy (GACI) is a rare autosomal recessive disease caused by mutations in ENPP1. Due to extensive calcification of the arterial media associated with intimal proliferation leading to vascular occlusion, most affected children die within the first 6 months of life. We report on two Taiwanese siblings with an identical genotype, but different clinical course. The male sibling developed heart failure and severe hypertension, and died at the age of 6 weeks despite of treatment with bisphosphonates, ACE inhibitors, and hydralazine. The subsequent female, who was monitored closely pre- and post-natally, is having an uncomplicated clinical course up to the age of 1(1/2) year now. There were similar characteristic sonographic and roentgenographic findings in both siblings in early infancy. In both siblings, the same compound heterozygous mutations (c.1025G > T [p.Gly342Val] and c.1112A > T [Tyr371Phe]) in ENPP1 were identified. Despite the same genotype and similar sonographic and radiographic features in early infancy, the phenotype of GACI can vary to a great extent within one family.
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Affiliation(s)
- Kun-Shan Cheng
- Department of Pediatrics, Mackay Memorial Hospital, Taipei, Taiwan
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431
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Johnson K, Polewski M, van Etten D, Terkeltaub R. Chondrogenesis mediated by PPi depletion promotes spontaneous aortic calcification in NPP1-/- mice. Arterioscler Thromb Vasc Biol 2004; 25:686-91. [PMID: 15625282 DOI: 10.1161/01.atv.0000154774.71187.f0] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE We recently linked human arterial media calcification of infancy to heritable PC-1/nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) deficiency. NPP1 hydrolyzes ATP to generate PP(i), a physicochemical inhibitor of hydroxyapatite crystal growth. But pathologic calcification in NPP1 deficiency states is tissue-restricted and in perispinal ligaments is endochondral differentiation-mediated rather than simply a dystrophic process. Because ectopic chondro-osseous differentiation promotes artery calcification in atherosclerosis and other disorders, we tested the hypothesis that NPP1 and PP(i) deficiencies regulate cell phenotype plasticity to promote artery calcification. METHODS AND RESULTS Using cultured multipotential NPP1-/- mouse bone marrow stromal cells, we demonstrated spontaneous chondrogenesis inhibitable by treatment with exogenous PP(i). We also demonstrated cartilage-specific gene expression, upregulated alkaline phosphatase, decreased expression of the physiological calcification inhibitor osteopontin, and increased calcification in NPP1-/- aortic smooth muscle cells (SMCs). Similar changes were demonstrated in aortic SMCs from ank/ank mice, which are extracellular PP(i)-depleted because of defective ANK transmembrane PP(i) transport activity. Moreover, NPP1-/- and ank/ank mice demonstrated aortic media calcification by von Kossa staining, and intra-aortic cartilage-specific collagen gene expression was demonstrated in situ in NPP1-/- mice. CONCLUSIONS NPP1 and PP(i) deficiencies modulate phenotype plasticity in artery SMCs and chondrogenesis in mesenchymal precursors, thereby stimulating artery calcification by modulating cell differentiation.
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MESH Headings
- Animals
- Aorta/enzymology
- Aorta/pathology
- Aorta/physiopathology
- Bone Marrow Cells/cytology
- Bone Marrow Cells/physiology
- Calcinosis/metabolism
- Calcinosis/pathology
- Calcinosis/physiopathology
- Cell Differentiation/physiology
- Cells, Cultured
- Chondrogenesis/physiology
- Diphosphates/metabolism
- Female
- Male
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/pathology
- Muscle, Smooth, Vascular/physiopathology
- Phenotype
- Phosphate Transport Proteins
- Phosphoric Diester Hydrolases/genetics
- Phosphoric Diester Hydrolases/metabolism
- Pyrophosphatases/genetics
- Pyrophosphatases/metabolism
- Stromal Cells/cytology
- Stromal Cells/physiology
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Affiliation(s)
- Kristen Johnson
- Rheumatology/Medicine, Veterans Affairs Medical Center/University of California at San Diego, School of Medicine, CA 92161, USA
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432
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Ea HK, Lioté F. Calcium pyrophosphate dihydrate and basic calcium phosphate crystal-induced arthropathies: update on pathogenesis, clinical features, and therapy. Curr Rheumatol Rep 2004; 6:221-7. [PMID: 15134602 DOI: 10.1007/s11926-004-0072-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Calcium-containing crystals are the most common class for the osteoarthritic joint. They are responsible for acute periarthritis and destructive arthropathies, and for tissue deposits mimicking tumor-like masses. These crystals encompassed mainly calcium pyrophosphate dihydrate and basic calcium phosphate crystals, with the latter being related to hydroxyapatite, carbonate-substituted apatite, and octacalcium phosphate. Calcification deposit mechanisms will be reviewed with respect to extracellular inorganic pyrophosphate dysregulation mainly caused by modulation of specific membrane channel disorders. Genetic defects have been extensively studied and identified mutation of specific genes such as ANKH and COL. Pathogenesis of crystal-induced inflammation is related to synovial tissue and direct cartilage activation. Besides classical knee or wrist pseudogout attacks or Milwaukee shoulder arthropathies, clinicians should be aware of other specific common presentations, such as erosive calcifications, spinal cord compression by intraspinal masses, ligamentum flavum calcification, or atypical calcified tophus. Promising clinical results for preventing calcium crystal deposits and cartilage degradation are lacking. Practical imaging tools are needed to monitor reduction of calcification of fibrocartilage and articular cartilage as markers of drug efficacy.
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Affiliation(s)
- Hang-Korng Ea
- Inserm U606 Fédération de Rhumatologie, Hôpital Lariboisière, 2 rue Ambroise Paré, F75475 Paris Cedex 10, France
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433
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Costello JC, Ryan LM. Modulation of chondrocyte production of extracellular inorganic pyrophosphate. Curr Opin Rheumatol 2004; 16:268-72. [PMID: 15103256 DOI: 10.1097/00002281-200405000-00017] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Extracellular inorganic pyrophosphate (ePPi) both inhibits and promotes different forms of pathologic mineralization. Basic calcium phosphate (BCP) deposition results from depressed levels of ePPi while excess levels of ePPi leads to calcium pyrophosphate dihydrate crystal deposition (CPPD) disease. These crystals are also often identified in patients with osteoarthritis, the most prevalent form of arthritis causing significant morbidity. RECENT STUDIES The two primary hypotheses for generation of ePPi, export of inorganic pyrophosphate through the multipass transmembrane protein ANK and generation of ePPi by ectoenzyme activity, continue to be supported and better understood through animal models and study of families with CPPD deposition disease. SUMMARY As the pathophysiology of crystal formation in both articular cartilage and synovial fluid is better understood, the opportunity for prevention and treatment of pathologic mineralization increases. In particular, a more complex understanding of the ank gene, ectoenzyme PC-1, and the transglutaminase enzyme family may eventually translate into therapeutic application for both BCP deposition and CPPD deposition disease.
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Affiliation(s)
- Jill C Costello
- Division of Rheumatology, Medical College of Wisconsin, 9200 West Wisconsin Avenue, Milwaukee, WI 53226, USA.
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434
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Abedin M, Tintut Y, Demer LL. Vascular calcification: mechanisms and clinical ramifications. Arterioscler Thromb Vasc Biol 2004; 24:1161-70. [PMID: 15155384 DOI: 10.1161/01.atv.0000133194.94939.42] [Citation(s) in RCA: 653] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular calcification, long thought to result from passive degeneration, involves a complex, regulated process of biomineralization resembling osteogenesis. Evidence indicates that proteins controlling bone mineralization are also involved in the regulation of vascular calcification. Artery wall cells grown in culture are induced to become osteogenic by inflammatory and atherogenic stimuli. Furthermore, osteoclast-like cells are found in calcified atherosclerotic plaques, and active resorption of ectopic vascular calcification has been demonstrated. In general, soft tissue calcification arises in areas of chronic inflammation, possibly functioning as a barrier limiting the spread of the inflammatory stimulus. Atherosclerotic calcification may be one example of this process, in which oxidized lipids are the inflammatory stimulus. Calcification is widely used as a clinical indicator of atherosclerosis. It progresses nonlinearly with time, following a sigmoid-shaped curve. The relationship between calcification and clinical events likely relates to mechanical instability introduced by calcified plaque at its interface with softer, noncalcified plaque. In general, as calcification proceeds, interface surface area increases initially, but eventually decreases as plaques coalesce. This phenomenon may account for reports of less calcification in unstable plaque. Vascular calcification is exacerbated in certain clinical entities, including diabetes, menopause, and osteoporosis. Mechanisms linking them must be considered in clinical decisions. For example, treatments for osteoporosis may have unanticipated effects on vascular calcification; the converse also applies. Further understanding of processes governing vascular calcification may yield new therapeutic options for vascular disease.
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Affiliation(s)
- Moeen Abedin
- Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, Calif 90095-1679, USA
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435
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Affiliation(s)
- Jürgen Floege
- Division of Nephrology and Immunology, University of Aachen, Aachen, Germany.
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436
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Vaingankar SM, Fitzpatrick TA, Johnson K, Goding JW, Maurice M, Terkeltaub R. Subcellular targeting and function of osteoblast nucleotide pyrophosphatase phosphodiesterase 1. Am J Physiol Cell Physiol 2004; 286:C1177-87. [PMID: 15075217 DOI: 10.1152/ajpcell.00320.2003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The ectonucleoside pyrophosphatase phosphodiesterase 1 (NPP1/PC-1) is a member of the NPP enzyme family that is critical in regulating mineralization. In certain mineralizing sites of bone and cartilage, membrane-limited vesicles [matrix vesicles (MVs)] provide a sheltered internal environment for nucleation of calcium-containing crystals, including hydroxyapatite. MV formation occurs by budding of vesicles from the plasma membrane of mineralizing cells. The MVs are enriched in proteins that promote mineralization. Paradoxically, NPP1, the type II transmembrane protein that generates the potent hydroxyapatite crystal growth inhibitor inorganic pyrophosphate (PPi), is also enriched in MVs. Although osteoblasts express NPP1, NPP2, and NPP3, only NPP1 is enriched in MVs. Therefore, this study uses mineralizing human osteoblastic SaOS-2 cells, a panel of NPP1 mutants, and NPP1 chimeras with NPP3, which does not concentrate in MVs, to investigate how NPP1 preferentially targets to MVs. We demonstrated that a cytosolic dileucine motif (amino acids 49–50) was critical in localizing NPP1 to regions of the plasma membrane that budded off into MVs. Moreover, transposition of the NPP1 cytoplasmic dileucine motif and flanking region (AAASLLAP) to NPP3 conferred to NPP3 the ability to target to the plasma membrane and, subsequently, concentrate in MVs. Functionally, the cytosolic tail dileucine motif NPP1 mutants lost the ability to support MV PPiconcentrations and to suppress calcification. The results identify a specific targeting motif in the NPP1 cytosolic tail that delivers PPi-generating NPP activity to osteoblast MVs for control of calcification.
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437
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Harmey D, Hessle L, Narisawa S, Johnson KA, Terkeltaub R, Millán JL, Liu S, Lu H, Verma A. Concerted regulation of inorganic pyrophosphate and osteopontin by akp2, enpp1, and ank: an integrated model of the pathogenesis of mineralization disorders. THE AMERICAN JOURNAL OF PATHOLOGY 2004. [PMID: 15039209 DOI: 10.1016/s0002-9440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Tissue-nonspecific alkaline phosphatase (TNAP) hydrolyzes the mineralization inhibitor inorganic pyrophosphate (PP(i)). Deletion of the TNAP gene (Akp2) in mice results in hypophosphatasia characterized by elevated levels of PP(i) and poorly mineralized bones, which are rescued by deletion of nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) that generates PP(i). Mice deficient in NPP1 (Enpp1(-/-)), or defective in the PP(i) channeling function of ANK (ank/ank), have decreased levels of extracellular PP(i) and are hypermineralized. Given the similarity in function between ANK and NPP1 we crossbred Akp2(-/-) mice to ank/ank mice and found a partial normalization of the mineralization phenotypes and PP(i) levels. Examination of Enpp1(-/-) and ank/ank mice revealed that Enpp1(-/-) mice have a more severe hypermineralized phenotype than ank/ank mice and that NPP1 but not ANK localizes to matrix vesicles, suggesting that failure of ANK deficiency to correct hypomineralization in Akp2(-/-) mice reflects the lack of ANK activity in the matrix vesicle compartment. We also found that the mineralization inhibitor osteopontin (OPN) was increased in Akp2(-/-), and decreased in ank/ank mice. PP(i) and OPN levels were normalized in [Akp2(-/-); Enpp1(-/-)] and [Akp2(-/-); ank/ank] mice, at both the mRNA level and in serum. Wild-type osteoblasts treated with PP(i) showed an increase in OPN, and a decrease in Enpp1 and Ank expression. Thus TNAP, NPP1, and ANK coordinately regulate PP(i) and OPN levels. The hypomineralization observed in Akp2(-/-) mice arises from the combined inhibitory effects of PP(i) and OPN. In contrast, NPP1 or ANK deficiencies cause a decrease in the PP(i) and OPN pools that leads to hypermineralization.
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438
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Harmey D, Hessle L, Narisawa S, Johnson KA, Terkeltaub R, Millán JL. Concerted regulation of inorganic pyrophosphate and osteopontin by akp2, enpp1, and ank: an integrated model of the pathogenesis of mineralization disorders. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 164:1199-209. [PMID: 15039209 PMCID: PMC1615351 DOI: 10.1016/s0002-9440(10)63208-7] [Citation(s) in RCA: 365] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/09/2003] [Indexed: 11/29/2022]
Abstract
Tissue-nonspecific alkaline phosphatase (TNAP) hydrolyzes the mineralization inhibitor inorganic pyrophosphate (PP(i)). Deletion of the TNAP gene (Akp2) in mice results in hypophosphatasia characterized by elevated levels of PP(i) and poorly mineralized bones, which are rescued by deletion of nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) that generates PP(i). Mice deficient in NPP1 (Enpp1(-/-)), or defective in the PP(i) channeling function of ANK (ank/ank), have decreased levels of extracellular PP(i) and are hypermineralized. Given the similarity in function between ANK and NPP1 we crossbred Akp2(-/-) mice to ank/ank mice and found a partial normalization of the mineralization phenotypes and PP(i) levels. Examination of Enpp1(-/-) and ank/ank mice revealed that Enpp1(-/-) mice have a more severe hypermineralized phenotype than ank/ank mice and that NPP1 but not ANK localizes to matrix vesicles, suggesting that failure of ANK deficiency to correct hypomineralization in Akp2(-/-) mice reflects the lack of ANK activity in the matrix vesicle compartment. We also found that the mineralization inhibitor osteopontin (OPN) was increased in Akp2(-/-), and decreased in ank/ank mice. PP(i) and OPN levels were normalized in [Akp2(-/-); Enpp1(-/-)] and [Akp2(-/-); ank/ank] mice, at both the mRNA level and in serum. Wild-type osteoblasts treated with PP(i) showed an increase in OPN, and a decrease in Enpp1 and Ank expression. Thus TNAP, NPP1, and ANK coordinately regulate PP(i) and OPN levels. The hypomineralization observed in Akp2(-/-) mice arises from the combined inhibitory effects of PP(i) and OPN. In contrast, NPP1 or ANK deficiencies cause a decrease in the PP(i) and OPN pools that leads to hypermineralization.
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439
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Doherty TM, Fitzpatrick LA, Shaheen A, Rajavashisth TB, Detrano RC. Genetic determinants of arterial calcification associated with atherosclerosis. Mayo Clin Proc 2004; 79:197-210. [PMID: 14959915 DOI: 10.4065/79.2.197] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Increasing research interest has focused on arterial calcification in the setting of atherosclerosis. Many features of atherosclerosis-related calcification provide useful clinical information. For example, calcium mineral deposits frequently form in atherosclerotic plaque, and intimal arterial calcification can be used as a surrogate marker for atherosclerosis; also, calcium deposits are readily and noninvasively quantified, which is useful because greater amounts of coronary calcification predict a higher risk of myocardial infarction and death. Several mechanisms leading to calcification associated with atherosclerosis have been proposed; however, no direct testing of proposed mechanisms has yet been reported. Studies in genetically altered animals and in humans have shed light on potential genetic determinants, which in turn could form the basis for a more comprehensive understanding of the factors affecting calcification within plaque and the associated pathobiologic implications. We review proposed molecular and cellular mechanisms of atherosclerosis-associated arterial calcification, summarize genetic influences, and suggest areas in which further investigation is needed. Understanding the molecular and genetic determinants of specific structural plaque components such as calcification can provide a solid foundation for the development of novel therapeutic approaches to favorably alter plaque structure and minimize vulnerability to arterial rupture.
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Affiliation(s)
- Terence M Doherty
- Burns and Allen Research Institute, Department of Medicine, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, Calif, USA
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