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Saffie-Siebert S, Alam I, Sutera FM, Dehsorkhi A, Torabi-Pour N, Baran-Rachwalska P, Iamartino L, Teti A, Maurizi A, Gerard-O'Riley RL, Acton D, Econs MJ. Effect of Allele-Specific Clcn7 G213R siRNA Delivered Via a Novel Nanocarrier on Bone Phenotypes in ADO2 Mice on 129S Background. Calcif Tissue Int 2024:10.1007/s00223-024-01222-3. [PMID: 38733412 DOI: 10.1007/s00223-024-01222-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/18/2024] [Indexed: 05/13/2024]
Abstract
Autosomal dominant osteopetrosis type 2 (ADO2) is a rare inherited bone disorder characterised by dense but brittle bones. It displays striking phenotypic variability, with the most severe symptoms, including blindness and bone marrow failure. Disease management largely relies on symptomatic treatment since there is no safe and effective treatment. Most ADO2 cases are caused by heterozygous loss-of-function mutations in the CLCN7 gene, which encodes an essential Cl-/H+ antiporter for proper bone resorption by osteoclasts. Thus, siRNA-mediated silencing of the mutant allele is a promising therapeutic approach, but targeting bone for first-in-human translation remains challenging. Here, we demonstrate the utility of silicon-stabilised hybrid lipid nanoparticles (sshLNPs) as a next-generation nucleic acid nanocarrier capable of delivering allele-specific siRNA to bone. Using a Clcn7G213R knock-in mouse model recapitulating one of the most common human ADO2 mutations and based on the 129S genetic background (which produces the most severe disease phenotype amongst current models), we show substantial knockdown of the mutant allele in femur when siRNA targeting the pathogenic variant is delivered by sshLNPs. We observed lower areal bone mineral density in femur and reduced trabecular thickness in femur and tibia, when siRNA-loaded sshLNPs were administered subcutaneously (representing the most relevant administration route for clinical adoption and patient adherence). Importantly, sshLNPs have improved stability over conventional LNPs and enable 'post hoc loading' for point-of-care formulation. The treatment was well tolerated, suggesting that sshLNP-enabled gene therapy might allow successful clinical translation of essential new treatments for ADO2 and potentially other rare genetic bone diseases.
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Affiliation(s)
| | - Imranul Alam
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | | | | | | | | | | | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | - Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | - Rita L Gerard-O'Riley
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Dena Acton
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Michael J Econs
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
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2
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Alam I, Hardman SL, Gerard-O'Riley RL, Acton D, Parker RS, Hong JM, Bruzzaniti A, Econs MJ. Effect of Roflumilast, a Selective PDE4 Inhibitor, on Bone Phenotypes in ADO2 Mice. Calcif Tissue Int 2024; 114:419-429. [PMID: 38300304 DOI: 10.1007/s00223-023-01180-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 12/25/2023] [Indexed: 02/02/2024]
Abstract
Autosomal Dominant Osteopetrosis type II (ADO2) is a rare bone disease of impaired osteoclastic bone resorption that usually results from heterozygous missense mutations in the chloride channel 7 (CLCN7) gene. We previously created mouse models of ADO2 (p.G213R) with one of the most common mutations (G215R) as found in humans and demonstrated that this mutation in mice phenocopies the human disease of ADO2. Previous studies have shown that roflumilast (RF), a selective phosphodiesterase 4 (PDE4) inhibitor that regulates the cAMP pathway, can increase osteoclast activity. We also observed that RF increased bone resorption in both wild-type and ADO2 heterozygous osteoclasts in vitro, suggesting it might rescue bone phenotypes in ADO2 mice. To test this hypothesis, we administered RF-treated diets (0, 20 and 100 mg/kg) to 8-week-old ADO2 mice for 6 months. We evaluated bone mineral density and bone micro-architecture using longitudinal in-vivo DXA and micro-CT at baseline, and 6-, 12-, 18-, and 24-week post-baseline time points. Additionally, we analyzed serum bone biomarkers (CTX, TRAP, and P1NP) at baseline, 12-, and 24-week post-baseline. Our findings revealed that RF treatment did not improve aBMD (whole body, femur, and spine) and trabecular BV/TV (distal femur) in ADO2 mice compared to the control group treated with a normal diet. Furthermore, we did not observe any significant changes in serum levels of bone biomarkers due to RF treatment in these mice. Overall, our results indicate that RF does not rescue the osteopetrotic bone phenotypes in ADO2 heterozygous mice.
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Affiliation(s)
- Imranul Alam
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | - Sara L Hardman
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Rita L Gerard-O'Riley
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Dena Acton
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Reginald S Parker
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Jung Min Hong
- Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202, USA
| | - Angela Bruzzaniti
- Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN, 46202, USA
| | - Michael J Econs
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Medical and Molecular Genetics, Indiana University School of Medicine, 1120 West Michigan St, CL459, Indianapolis, IN, 46202, USA
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3
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Hong JM, Gerard-O'Riley RL, Acton D, Alam I, Econs MJ, Bruzzaniti A. The PDE4 Inhibitors Roflumilast and Rolipram Rescue ADO2 Osteoclast Resorption Dysfunction. Calcif Tissue Int 2024; 114:430-443. [PMID: 38483547 DOI: 10.1007/s00223-024-01191-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/29/2024] [Indexed: 03/22/2024]
Abstract
Autosomal Dominant Osteopetrosis type II (ADO2) is a rare bone disease of impaired osteoclastic bone resorption caused by heterozygous missense mutations in the chloride channel 7 (CLCN7). Adenylate cyclase, which catalyzes the formation of cAMP, is critical for lysosomal acidification in osteoclasts. We found reduced cAMP levels in ADO2 osteoclasts compared to wild-type (WT) osteoclasts, leading us to examine whether regulating cAMP would improve ADO2 osteoclast activity. Although forskolin, a known activator of adenylate cyclase and cAMP levels, negatively affected osteoclast number, it led to an overall increase in ADO2 and WT osteoclast resorption activity in vitro. Next, we examined cAMP hydrolysis by the phosphodiesterase 4 (PDE4) proteins in ADO2 versus WT osteoclasts. QPCR analysis revealed higher expression of the three major PDE4 subtypes (4a, 4b, 4d) in ADO2 osteoclasts compared in WT, consistent with reduced cAMP levels in ADO2 osteoclasts. In addition, we found that the PDE4 antagonists, rolipram and roflumilast, stimulated ADO2 and WT osteoclast formation in a dose-dependent manner. Importantly, roflumilast and rolipram displayed a concentration-dependent increase in osteoclast resorption activity which was greater in ADO2 than WT osteoclasts. Moreover, treatment with roflumilast rescued cAMP levels in ADO2 OCLs. The key findings from our studies demonstrate that osteoclasts from ADO2 mice exhibit reduced cAMP levels and PDE4 inhibition rescues cAMP levels and ADO2 osteoclast activity dysfunction in vitro. The mechanism of action of PDE4 inhibitors and their ability to reduce the high bone mass of ADO2 mice in vivo are currently under investigation. Importantly, these studies advance the understanding of the mechanisms underlying the ADO2 osteoclast dysfunction which is critical for the development of therapeutic approaches to treat clinically affected ADO2 patients.
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Affiliation(s)
- Jung Min Hong
- Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, 1121 West Michigan Street, DS266, Indianapolis, IN, 46202, USA
| | - Rita L Gerard-O'Riley
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Dena Acton
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Imranul Alam
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Michael J Econs
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Angela Bruzzaniti
- Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, 1121 West Michigan Street, DS266, Indianapolis, IN, 46202, USA.
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Maurizi A, Patrizii P, Teti A, Sutera FM, Baran-Rachwalska P, Burns C, Nandi U, Welsh M, Torabi-Pour N, Dehsorkhi A, Saffie-Siebert S. Novel hybrid silicon-lipid nanoparticles deliver a siRNA to cure autosomal dominant osteopetrosis in mice. Implications for gene therapy in humans. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 33:925-937. [PMID: 37680985 PMCID: PMC10480457 DOI: 10.1016/j.omtn.2023.08.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 08/16/2023] [Indexed: 09/09/2023]
Abstract
Rare skeletal diseases are still in need of proper clinically available transfection agents as the major challenge for first-in-human translation relates to intrinsic difficulty in targeting bone without exacerbating any inherent toxicity due to used vector. SiSaf's silicon stabilized hybrid lipid nanoparticles (sshLNPs) constitute next-generation non-viral vectors able to retain the integrity and stability of constructs and to accommodate considerable payloads of biologicals, without requiring cold-chain storage. sshLNP was complexed with a small interfering RNA (siRNA) specifically designed against the human CLCN7G215R mRNA. When tested via single intraperitoneal injection in pre-puberal autosomal dominant osteopetrosis type 2 (ADO2) mice, carrying a heterozygous mutation of the Clcn7 gene (Clcn7G213R), sshLNP, this significantly downregulated the Clcn7G213R related mRNA levels in femurs at 48 h. Confirmatory results were observed at 2 weeks and 4 weeks after treatments (3 intraperitoneal injections/week), with rescue of the bone phenotype and demonstrating safety. The pre-clinical results will enable advanced preclinical development of RNA-based therapy for orphan and genetic skeletal disorders by safely and effectively delivering biologicals of interest to cure human systemic conditions.
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Affiliation(s)
- Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L'Aquila, Italy
| | - Piergiorgio Patrizii
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L'Aquila, Italy
| | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L'Aquila, Italy
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Cao X, Lenk GM, Mikusevic V, Mindell JA, Meisler MH. The chloride antiporter CLCN7 is a modifier of lysosome dysfunction in FIG 4 and VAC14 mutants. PLoS Genet 2023; 19:e1010800. [PMID: 37363915 DOI: 10.1371/journal.pgen.1010800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 05/26/2023] [Indexed: 06/28/2023] Open
Abstract
The phosphatase FIG 4 and the scaffold protein VAC14 function in the biosynthesis of PI(3,5)P2, a signaling lipid that inhibits the lysosomal chloride transporter ClC-7. Loss-of-function mutations of FIG 4 and VAC14 reduce PI(3,5)P2 and result in lysosomal disorders characterized by accumulation of enlarged lysosomes and neurodegeneration. Similarly, a gain of function mutation of CLCN7 encoding ClC-7 also results in enlarged lysosomes. We therefore tested the ability of reduced CLCN7 expression to compensate for loss of FIG 4 or VAC14. Knock-out of CLCN7 corrected lysosomal swelling and partially corrected lysosomal hyperacidification in FIG 4 null cell cultures. Knockout of the related transporter CLCN6 (ClC-6) in FIG 4 null cells did not affect the lysosome phenotype. In the Fig 4 null mouse, reduction of ClC-7 by expression of the dominant negative CLCN7 variant p.Gly215Arg improved growth and neurological function and increased lifespan by 20%. These observations demonstrate a role for the CLCN7 chloride transporter in pathogenesis of FIG 4 and VAC14 disorders. Reduction of CLCN7 provides a new target for treatment of FIG 4 and VAC14 deficiencies that lack specific therapies, such as Charcot-Marie-Tooth Type 4J and Yunis-Varón syndrome.
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Affiliation(s)
- Xu Cao
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Guy M Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Vedrana Mikusevic
- Membrane Transport Biophysics Section, National Institutes of Neurological Disorders and Stroke, Bethesda, Maryland, United States of America
| | - Joseph A Mindell
- Membrane Transport Biophysics Section, National Institutes of Neurological Disorders and Stroke, Bethesda, Maryland, United States of America
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
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Ma Y, Xu Y, Zhang Y, Duan X. Molecular Mechanisms of Craniofacial and Dental Abnormalities in Osteopetrosis. Int J Mol Sci 2023; 24:10412. [PMID: 37373559 DOI: 10.3390/ijms241210412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
Osteopetrosis is a group of genetic bone disorders characterized by increased bone density and defective bone resorption. Osteopetrosis presents a series of clinical manifestations, including craniofacial deformities and dental problems. However, few previous reports have focused on the features of craniofacial and dental problems in osteopetrosis. In this review, we go through the clinical features, types, and related pathogenic genes of osteopetrosis. Then we summarize and describe the characteristics of craniofacial and dental abnormalities in osteopetrosis that have been published in PubMed from 1965 to the present. We found that all 13 types of osteopetrosis have craniomaxillofacial and dental phenotypes. The main pathogenic genes, such as chloride channel 7 gene (CLCN7), T cell immune regulator 1 (TCIRG1), osteopetrosis-associated transmembrane protein 1 (OSTM1), pleckstrin homology domain-containing protein family member 1 (PLEKHM1), and carbonic anhydrase II (CA2), and their molecular mechanisms involved in craniofacial and dental phenotypes, are discussed. We conclude that the telltale craniofacial and dental abnormalities are important for dentists and other clinicians in the diagnosis of osteopetrosis and other genetic bone diseases.
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Affiliation(s)
- Yu Ma
- College of Life Sciences, Northwest University, Xi'an 710069, China
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Disease, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an 710032, China
| | - Yali Xu
- College of Life Sciences, Northwest University, Xi'an 710069, China
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Disease, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an 710032, China
| | - Yanli Zhang
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Disease, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an 710032, China
| | - Xiaohong Duan
- State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Disease, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an 710032, China
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7
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Maurizi A. Experimental therapies for osteopetrosis. Bone 2022; 165:116567. [PMID: 36152941 DOI: 10.1016/j.bone.2022.116567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 09/13/2022] [Accepted: 09/20/2022] [Indexed: 11/17/2022]
Abstract
The medical treatment of osteopetrosis is an ongoing clinical problem. There are no effective and safer therapeutic approaches for all its forms. However, recent discoveries concerning the etiology and the pathogenesis of osteopetrosis, the development of dedicated cellular and animal models, and the advent of new technologies are paving the way for the development of targeted and safer therapies for both lethal and milder osteopetrosis. This review summarizes the huge effort and successes made by researchers to identify and develop new experimental approaches with this objective, such as the use of non-genotoxic myeloablation, gene correction of inducible Pluripotent Stem Cells (iPSCs), lentiviral-based gene therapy, protein replacement, prenatal treatment, osteoclast precursors transplantation and RNA Interference.
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Affiliation(s)
- Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
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Alam I, Gerard-O’Riley RL, Acton D, Hardman SL, Murphy M, Alvarez MB, Blosser RJ, Sinn A, Srour EF, Kacena MA, Econs MJ. Bone marrow transplantation as a therapy for autosomal dominant osteopetrosis type 2 in mice. FASEB J 2022; 36:e22471. [PMID: 35959867 PMCID: PMC9397585 DOI: 10.1096/fj.202200678r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/01/2022] [Accepted: 07/14/2022] [Indexed: 01/02/2023]
Abstract
Autosomal dominant osteopetrosis type II (ADO2) is a heritable bone disease of impaired osteoclastic bone resorption caused by missense mutations in the chloride channel 7 (CLCN7) gene. Clinical features of ADO2 include fractures, osteomyelitis of jaw, vision loss, and in severe cases, bone marrow failure. Currently, there is no effective therapy for ADO2, and patients usually receive symptomatic treatments. Theoretically, bone marrow transplantation (BMT), which is commonly used in recessive osteopetrosis, could be used to treat ADO2, although the frequency of complications related to BMT is quite high. We created an ADO2 knock-in (p.G213R mutation) mouse model on the 129 genetic background, and their phenotypes mimic the human disease of ADO2. To test whether BMT could restore osteoclast function and rescue the bone phenotypes in ADO2 mice, we transplanted bone marrow cells from 6-8 weeks old male WT donor mice into recipient female ADO2 mice. Also, to determine whether age at the time of transplant may play a role in transplant success, we performed BMT in young (12-week-old) and old (9-month-old) ADO2 mice. Our data indicate that ADO2 mice transplanted with WT marrow achieved more than 90% engraftment up to 6 months post-transplantation at both young and old ages. The in-vivo DXA data revealed that young ADO2 mice transplanted with WT marrow had significantly lower whole body and spine areal bone mineral density (aBMD) at month 6 post-transplantation compared to the ADO2 control mice. The old ADO2 mice also displayed significantly lower whole body, femur, and spine aBMD at months 4 and 5 post-transplantation compared to the age-matched control mice. The in-vivo micro-CT data showed that ADO2 experimental mice transplanted with WT marrow had significantly lower BV/TV at months 2 and 4 post-transplantation compared to the ADO2 control mice at a young age. In contrast, ADO2 control and experimental mice displayed similar BV/TV values for all post-transplantation time points at old age. In addition, serum CTX was significantly higher at month 2 post-transplantation in both young and old ADO2 experimental mice compared to the ADO2 control mice. Serum P1NP levels in young ADO2 experimental mice were significantly higher at baseline and month 2 post-transplantation compared to the ADO2 control mice. These data suggest that BMT may provide, at least, some beneficial effect at both young and adult ages.
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Affiliation(s)
- Imranul Alam
- Medicine, Indiana University School of Medicine, IN 46202, USA
| | | | - Dena Acton
- Medicine, Indiana University School of Medicine, IN 46202, USA
| | - Sara L. Hardman
- Medicine, Indiana University School of Medicine, IN 46202, USA
| | - Madeline Murphy
- Medicine, Indiana University School of Medicine, IN 46202, USA
| | - Marta B. Alvarez
- Orthopaedic Surgery, Indiana University School of Medicine, IN 46202, USA
| | - Rachel J. Blosser
- Orthopaedic Surgery, Indiana University School of Medicine, IN 46202, USA
| | - Anthony Sinn
- Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, IN 46202, USA
| | - Edward F. Srour
- Medicine, Indiana University School of Medicine, IN 46202, USA
- Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, IN 46202, USA
| | - Melissa A. Kacena
- Orthopaedic Surgery, Indiana University School of Medicine, IN 46202, USA
- Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, IN 46202, USA
| | - Michael J. Econs
- Medicine, Indiana University School of Medicine, IN 46202, USA
- Medical and Molecular Genetics, Indiana University School of Medicine, IN 46202, USA
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The Role of the Lysosomal Cl−/H+ Antiporter ClC-7 in Osteopetrosis and Neurodegeneration. Cells 2022; 11:cells11030366. [PMID: 35159175 PMCID: PMC8833911 DOI: 10.3390/cells11030366] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/16/2022] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
CLC proteins comprise Cl− channels and anion/H+ antiporters involved in several fundamental physiological processes. ClC-7 is a lysosomal Cl−/H+ antiporter that together with its beta subunit Ostm1 has a critical role in the ionic homeostasis of lysosomes and of the osteoclasts’ resorption lacuna, although the specific underlying mechanism has so far remained elusive. Mutations in ClC-7 cause osteopetrosis, but also a form of lysosomal storage disease and neurodegeneration. Interestingly, both loss-of- and gain-of-function mutations of ClC-7 can be pathogenic, but the mechanistic implications of this finding are still unclear. This review will focus on the recent advances in our understanding of the biophysical properties of ClC-7 and of its role in human diseases with a focus on osteopetrosis and neurodegeneration.
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Li C, Shangguan Y, Zhu P, Dai W, Tang D, Ou M, Dai Y. Multiomics landscape of the autosomal dominant osteopetrosis type II disease-specific induced pluripotent stem cells. Hereditas 2021; 158:40. [PMID: 34702373 PMCID: PMC8549315 DOI: 10.1186/s41065-021-00204-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/08/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Autosomal dominant osteopetrosis type II (ADO2) is a genetically and phenotypically metabolic bone disease, caused by osteoclast abnormalities. The pathways dysregulated in ADO2 could lead to the defects in osteoclast formation and function. However, the mechanism remains elusive. MATERIALS AND METHODS To systematically explore the molecular characterization of ADO2, we performed a multi-omics profiling from the autosomal dominant osteopetrosis type II iPSCs (ADO2-iPSCs) and healthy normal control iPSCs (NC-iPSCs) using whole genome re-sequencing, DNA methylation and N6-methyladenosine (m6A) analysis in this study. RESULTS Totally, we detected 7,095,817 single nucleotide polymorphisms (SNPs) and 1,179,573 insertion and deletions (InDels), 1,001,943 differentially methylated regions (DMRs) and 2984 differential m6A peaks, and the comprehensive multi-omics profile was generated from the two cells. Interestingly, the ISG15 m6A level in ADO2-iPSCs is higher than NC-iPSCs by IGV software, and the differentially expressed m6A-modified genes (DEMGs) were highly enriched in the osteoclast differentiation and p53 signaling pathway, which associated with the development of osteopetrosis. In addition, combining our previously published transcriptome and proteome datasets, we found that the change in DNA methylation levels correlates inversely with some gene expression levels. CONCLUSION Our results indicate that the global multi-omics landscape not only provides a high-quality data resource but also reveals a dynamic pattern of gene expression, and found that the pathogenesis of ADO2 may begin early in life.
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Affiliation(s)
- Chunhong Li
- Central Laboratory, Guangxi Health Commission Key Laboratory of Glucose and Lipid Metabolism Disorders, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, 541199, People's Republic of China
| | - Yu Shangguan
- Clinical Medical Research Center, Guangdong Provincial Engineering Research Center of Autoimmune Disease Precision Medicine, Shenzhen Engineering Research Center of Autoimmune Disease, The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology, Shenzhen People's Hospital, Shenzhen, Guangdong, 518020, People's Republic of China.,Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin, NO. 924 Hospital, Guilin, 541002, People's Republic of China
| | - Peng Zhu
- Clinical Medical Research Center, Guangdong Provincial Engineering Research Center of Autoimmune Disease Precision Medicine, Shenzhen Engineering Research Center of Autoimmune Disease, The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology, Shenzhen People's Hospital, Shenzhen, Guangdong, 518020, People's Republic of China
| | - Weier Dai
- College of Natural Science, University of Texas at Austin, Austin, TX, 78712, USA
| | - Donge Tang
- Clinical Medical Research Center, Guangdong Provincial Engineering Research Center of Autoimmune Disease Precision Medicine, Shenzhen Engineering Research Center of Autoimmune Disease, The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology, Shenzhen People's Hospital, Shenzhen, Guangdong, 518020, People's Republic of China.
| | - Minglin Ou
- Central Laboratory, Guangxi Health Commission Key Laboratory of Glucose and Lipid Metabolism Disorders, The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, 541199, People's Republic of China.
| | - Yong Dai
- Clinical Medical Research Center, Guangdong Provincial Engineering Research Center of Autoimmune Disease Precision Medicine, Shenzhen Engineering Research Center of Autoimmune Disease, The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology, Shenzhen People's Hospital, Shenzhen, Guangdong, 518020, People's Republic of China.
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11
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Formosa MM, Bergen DJM, Gregson CL, Maurizi A, Kämpe A, Garcia-Giralt N, Zhou W, Grinberg D, Ovejero Crespo D, Zillikens MC, Williams GR, Bassett JHD, Brandi ML, Sangiorgi L, Balcells S, Högler W, Van Hul W, Mäkitie O. A Roadmap to Gene Discoveries and Novel Therapies in Monogenic Low and High Bone Mass Disorders. Front Endocrinol (Lausanne) 2021; 12:709711. [PMID: 34539568 PMCID: PMC8444146 DOI: 10.3389/fendo.2021.709711] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/12/2021] [Indexed: 12/24/2022] Open
Abstract
Genetic disorders of the skeleton encompass a diverse group of bone diseases differing in clinical characteristics, severity, incidence and molecular etiology. Of particular interest are the monogenic rare bone mass disorders, with the underlying genetic defect contributing to either low or high bone mass phenotype. Extensive, deep phenotyping coupled with high-throughput, cost-effective genotyping is crucial in the characterization and diagnosis of affected individuals. Massive parallel sequencing efforts have been instrumental in the discovery of novel causal genes that merit functional validation using in vitro and ex vivo cell-based techniques, and in vivo models, mainly mice and zebrafish. These translational models also serve as an excellent platform for therapeutic discovery, bridging the gap between basic science research and the clinic. Altogether, genetic studies of monogenic rare bone mass disorders have broadened our knowledge on molecular signaling pathways coordinating bone development and metabolism, disease inheritance patterns, development of new and improved bone biomarkers, and identification of novel drug targets. In this comprehensive review we describe approaches to further enhance the innovative processes taking discoveries from clinic to bench, and then back to clinic in rare bone mass disorders. We highlight the importance of cross laboratory collaboration to perform functional validation in multiple model systems after identification of a novel disease gene. We describe the monogenic forms of rare low and high rare bone mass disorders known to date, provide a roadmap to unravel the genetic determinants of monogenic rare bone mass disorders using proper phenotyping and genotyping methods, and describe different genetic validation approaches paving the way for future treatments.
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Affiliation(s)
- Melissa M. Formosa
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta
- Centre for Molecular Medicine and Biobanking, University of Malta, Msida, Malta
| | - Dylan J. M. Bergen
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
- The Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Celia L. Gregson
- The Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Antonio Maurizi
- Department of Applied Clinical Sciences and Biotechnological, University of L’Aquila, L’Aquila, Italy
| | - Anders Kämpe
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Natalia Garcia-Giralt
- IMIM (Hospital del Mar Research Institute), Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Barcelona, Spain
| | - Wei Zhou
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Daniel Grinberg
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Institut de Biomedicina de la Universitat de Barcelona (IBUB), Institut de Recerca Sant Joan de Déu (IRSJD), Barcelona, Spain
| | - Diana Ovejero Crespo
- IMIM (Hospital del Mar Research Institute), Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Barcelona, Spain
| | - M. Carola Zillikens
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Graham R. Williams
- Molecular Endocrinology Laboratory, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom
| | - J. H. Duncan Bassett
- Molecular Endocrinology Laboratory, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom
| | - Maria Luisa Brandi
- Department of Surgery and Translational Medicine (M.L.B.), University of Florence, Florence, Italy
| | - Luca Sangiorgi
- Department of Medical Genetics and Skeletal Rare Diseases, IRCCS Rizzoli Orthopaedic Institute, Bologna, Italy
| | - Susanna Balcells
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Institut de Biomedicina de la Universitat de Barcelona (IBUB), Institut de Recerca Sant Joan de Déu (IRSJD), Barcelona, Spain
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
| | - Wim Van Hul
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Outi Mäkitie
- Children’s Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Folkhälsan Research Centre, Folkhälsan Institute of Genetics, Helsinki, Finland
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12
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Norwood I, Szondi D, Ciocca M, Coudert A, Cohen-Solal M, Rucci N, Teti A, Maurizi A. Transcriptomic and bioinformatic analysis of Clcn7-dependent Autosomal Dominant Osteopetrosis type 2. Preclinical and clinical implications. Bone 2021; 144:115828. [PMID: 33359007 DOI: 10.1016/j.bone.2020.115828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/26/2020] [Accepted: 12/17/2020] [Indexed: 12/30/2022]
Abstract
Autosomal Dominant Osteopetrosis type 2 (ADO2) is a rare genetic disease characterized by dense yet fragile bones. To date, the radiological approach remains the gold standard for ADO2 diagnosis. However, recent observations unveiled that ADO2 is a systemic disease affecting various organs beyond bone, including lung, kidney, muscle, and brain. Monitoring disease status and progression would greatly benefit from specific biomarkers shared by the affected organs. In this work, data derived from RNA deep sequencing (RNA dSeq) of bone, lung, kidney, muscle, brain, and osteoclasts isolated from wildtype (WT) and Clcn7G213R ADO2 mice were subjected to gene ontology and pathway analyses. Results showed the presence of alterations in gene ontology terms and pathways associated with bone metabolism and osteoclast biology, including JAK-STAT, cytokine-cytokine receptor, and hematopoietic cell lineage. Furthermore, in line with the multiorgan alterations caused by ADO2, the analysis of soft organs showed an enrichment of PPAR and neuroactive ligand-receptor interaction pathways known to be involved in the onset of tissue fibrosis and behavioral alterations, respectively. Finally, we observed the modulations of potential ADO2 biomarkers in organs and cells of ADO2 mice and in the peripheral blood mononuclear cells of patients, using conventional methods. Of note, some of these biomarkers could be possibly responsive to an effective experimental therapy based on a mutation-specific siRNA. Overall, the identified gene signature and the soluble forms of the encoded proteins could potentially represent reliable disease biomarkers that could improve the ADO2 diagnosis, the monitoring of both the skeletal and non-skeletal dysfunctions, and the assessment of the response to therapy.
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Affiliation(s)
- Iona Norwood
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Denis Szondi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Michela Ciocca
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Amélie Coudert
- Université de Paris, INSERM U 1132 Bioscar and Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Martine Cohen-Solal
- Université de Paris, INSERM U 1132 Bioscar and Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Nadia Rucci
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
| | - Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
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13
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Bose S, He H, Stauber T. Neurodegeneration Upon Dysfunction of Endosomal/Lysosomal CLC Chloride Transporters. Front Cell Dev Biol 2021; 9:639231. [PMID: 33708769 PMCID: PMC7940362 DOI: 10.3389/fcell.2021.639231] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/03/2021] [Indexed: 12/15/2022] Open
Abstract
The regulation of luminal ion concentrations is critical for the function of, and transport between intracellular organelles. The importance of the acidic pH in the compartments of the endosomal-lysosomal pathway has been well-known for decades. Besides the V-ATPase, which pumps protons into their lumen, a variety of ion transporters and channels is involved in the regulation of the organelles' complex ion homeostasis. Amongst these are the intracellular members of the CLC family, ClC-3 through ClC-7. They localize to distinct but overlapping compartments of the endosomal-lysosomal pathway, partially with tissue-specific expression. Functioning as 2Cl−/H+ exchangers, they can support the vesicular acidification and accumulate luminal Cl−. Mutations in the encoding genes in patients and mouse models underlie severe phenotypes including kidney stones with CLCN5 and osteopetrosis or hypopigmentation with CLCN7. Dysfunction of those intracellular CLCs that are expressed in neurons lead to neuronal defects. Loss of endosomal ClC-3, which heteromerizes with ClC-4, results in neurodegeneration. Mutations in ClC-4 are associated with epileptic encephalopathy and intellectual disability. Mice lacking the late endosomal ClC-6 develop a lysosomal storage disease with reduced pain sensitivity. Human gene variants have been associated with epilepsy, and a gain-of-function mutation causes early-onset neurodegeneration. Dysfunction of the lysosomal ClC-7 leads to a lysosomal storage disease and neurodegeneration in mice and humans. Reduced luminal chloride, as well as altered calcium regulation, has been associated with lysosomal storage diseases in general. This review discusses the properties of endosomal and lysosomal Cl−/H+ exchange by CLCs and how various alterations of ion transport by CLCs impact organellar ion homeostasis and function in neurodegenerative disorders.
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Affiliation(s)
- Shroddha Bose
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Hailan He
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
| | - Tobias Stauber
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Department of Human Medicine and Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
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14
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Sims NA, Martin TJ. Osteoclasts Provide Coupling Signals to Osteoblast Lineage Cells Through Multiple Mechanisms. Annu Rev Physiol 2019; 82:507-529. [PMID: 31553686 DOI: 10.1146/annurev-physiol-021119-034425] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bone remodeling is essential for the repair and replacement of damaged and old bone. The major principle underlying this process is that osteoclast-mediated resorption of a quantum of bone is followed by osteoblast precursor recruitment; these cells differentiate to matrix-producing osteoblasts, which form new bone to replace what was resorbed. Evidence from osteopetrotic syndromes indicate that osteoclasts not only resorb bone, but also provide signals to promote bone formation. Osteoclasts act upon osteoblast lineage cells throughout their differentiation by facilitating growth factor release from resorbed matrix, producing secreted proteins and microvesicles, and expressing membrane-bound factors. These multiple mechanisms mediate the coupling of bone formation to resorption in remodeling. Additional interactions of osteoclasts with osteoblast lineage cells, including interactions with canopy and reversal cells, are required to achieve coordination between bone formation and resorption during bone remodeling.
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Affiliation(s)
- Natalie A Sims
- Bone Cell Biology and Disease Unit, St. Vincent's Institute of Medical Research, Melbourne, Victoria 3065, Australia; , .,Department of Medicine, The University of Melbourne, St. Vincent's Hospital, Melbourne, Victoria 3065, Australia
| | - T John Martin
- Bone Cell Biology and Disease Unit, St. Vincent's Institute of Medical Research, Melbourne, Victoria 3065, Australia; , .,Department of Medicine, The University of Melbourne, St. Vincent's Hospital, Melbourne, Victoria 3065, Australia
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15
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Ou M, Li C, Tang D, Xue W, Xu Y, Zhu P, Li B, Xie J, Chen J, Sui W, Yin L, Dai Y. Genotyping, generation and proteomic profiling of the first human autosomal dominant osteopetrosis type II-specific induced pluripotent stem cells. Stem Cell Res Ther 2019; 10:251. [PMID: 31412925 PMCID: PMC6693165 DOI: 10.1186/s13287-019-1369-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/14/2022] Open
Abstract
Background Autosomal dominant osteopetrosis type II (ADO2) is a rare human genetic disease that has been broadly studied as an important osteopetrosis model; however, there are no disease-specific induced pluripotent stem cells (ADO2-iPSCs) that may be valuable for understanding the pathogenesis and may be a potential source of cells for autologous cell-based therapies. Methods To generate the first human ADO2-iPSCs from a Chinese family with ADO2 and to identify their characteristics, blood samples were collected from the proband and his parents and were used for genotyping by whole-exome sequencing (WES); the urine-derived cells of the proband were reprogrammed with episomal plasmids that contained transcription factors, such as KLF4, OCT4, c-MYC, and SOX2. The proteome-wide protein quantification and lysine 2-hydroxyisobutyrylation detection of the ADO2-iPSCs and normal control iPSCs (NC-iPSCs) were performed by high-resolution LC-MS/MS and bioinformatics analysis. Results WES with filtering strategies identified a mutation in CLCN7 (R286W) in the proband and his father, which was absent in the proband’s mother and the healthy controls; this was confirmed by Sanger sequencing. The ADO2-iPSCs were successfully generated, which carried a normal male karyotype (46, XY) and the mutation of CLCN7 (R286W); the ADO2-iPSCs positively expressed alkaline phosphatase and other surface markers; and no vector and transgene were detected. The ADO2-iPSCs could differentiate into all three germ cell layers, both in vitro and in vivo. The proteomic profiling revealed similar expression of pluripotency markers in the two cell lines and identified 7405 proteins and 3664 2-hydroxyisobutyrylated peptides in 1036 proteins in the ADO2-iPSCs. Conclusions Our data indicated that the mutation CLCN7 (R286W) may be a cause of the osteopetrosis family. The generated vector-free and transgene-free ADO2-iPSCs with known proteomic characteristics may be valuable for personalized and cell-based regenerative medicine in the future. Electronic supplementary material The online version of this article (10.1186/s13287-019-1369-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Minglin Ou
- Clinical Medical Research Center of The Second Clinical Medical College, Jinan University, Shenzhen People's Hospital, No.1017, Dongmen North Road, Luohu District, Shenzhen, 518020, China.,Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin No. 181 Hospital, No. 1, Xinqiaoyuan Road, Guilin, 541002, China
| | - Chunhong Li
- Clinical Medical Research Center of The Second Clinical Medical College, Jinan University, Shenzhen People's Hospital, No.1017, Dongmen North Road, Luohu District, Shenzhen, 518020, China.,Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin No. 181 Hospital, No. 1, Xinqiaoyuan Road, Guilin, 541002, China.,College of Life Science, Guangxi Normal University, Guilin, 541004, China
| | - Donge Tang
- Clinical Medical Research Center of The Second Clinical Medical College, Jinan University, Shenzhen People's Hospital, No.1017, Dongmen North Road, Luohu District, Shenzhen, 518020, China.,Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin No. 181 Hospital, No. 1, Xinqiaoyuan Road, Guilin, 541002, China
| | - Wen Xue
- Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin No. 181 Hospital, No. 1, Xinqiaoyuan Road, Guilin, 541002, China
| | - Yong Xu
- Clinical Medical Research Center of The Second Clinical Medical College, Jinan University, Shenzhen People's Hospital, No.1017, Dongmen North Road, Luohu District, Shenzhen, 518020, China
| | - Peng Zhu
- Clinical Medical Research Center of The Second Clinical Medical College, Jinan University, Shenzhen People's Hospital, No.1017, Dongmen North Road, Luohu District, Shenzhen, 518020, China
| | - Bo Li
- Clinical Medical Research Center of The Second Clinical Medical College, Jinan University, Shenzhen People's Hospital, No.1017, Dongmen North Road, Luohu District, Shenzhen, 518020, China
| | - Jiansheng Xie
- Shenzen Maternity & Child Healthcare Hospital, Shenzhen, 518017, China
| | - Jiejing Chen
- Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin No. 181 Hospital, No. 1, Xinqiaoyuan Road, Guilin, 541002, China
| | - Weiguo Sui
- Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin No. 181 Hospital, No. 1, Xinqiaoyuan Road, Guilin, 541002, China
| | - Lianghong Yin
- Department of Nephrology, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, China
| | - Yong Dai
- Clinical Medical Research Center of The Second Clinical Medical College, Jinan University, Shenzhen People's Hospital, No.1017, Dongmen North Road, Luohu District, Shenzhen, 518020, China. .,Guangxi Key Laboratory of Metabolic Disease Research, Central Laboratory of Guilin No. 181 Hospital, No. 1, Xinqiaoyuan Road, Guilin, 541002, China.
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16
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Imel EA, Liu Z, Acton D, Coffman M, Gebregziabher N, Tong Y, Econs MJ. Interferon Gamma-1b Does Not Increase Markers of Bone Resorption in Autosomal Dominant Osteopetrosis. J Bone Miner Res 2019; 34:1436-1445. [PMID: 30889272 PMCID: PMC6697186 DOI: 10.1002/jbmr.3715] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 02/27/2019] [Accepted: 03/10/2019] [Indexed: 12/24/2022]
Abstract
In autosomal dominant osteopetrosis type 2 (ADO2) CLCN7 mutations cause impaired osteoclast function. Severe consequences include skeletal fragility despite high bone mass, osteomyelitis, osteonecrosis, bone marrow failure, and severe cranial nerve impingement. There is no effective medical treatment for ADO2. We recruited subjects with ADO2 into a 14-week, open-label, pilot clinical trial of interferon gamma-1b. Doses were titrated based on tolerability and if fasting serum C-telopeptide (CTX) was <25% above baseline at week 8, targeting doses of 100 µg/m2 three times a week. The primary outcomes were change from baseline in CTX and N-telopeptide/creatinine ratio (NTX/Cr) at week 14. Secondary outcomes included changes in urine calcium/creatinine ratio, bone formation markers and tolerability. Nine adults and three children were recruited. Severe manifestations of ADO2 included histories of fractures (100%), osteomyelitis (16.7%), vision loss (50%), and anemia (58.3%). Baseline CTX and NTX/Cr were generally low-normal. Procollagen type I N-terminal propeptide was elevated or in the upper-normal range in 11 of 12 (91.6%) subjects. Elevations of aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were common. One subject withdrew due to rash. Five subjects achieved doses of 50 µg/m2 3 days a week, while six reached the full dose of 100 µg/m2 3 days a week. Only 3 of 11 (27.3%) completing subjects achieved the primary outcome of increasing CTX ≥25% above baseline at week 14. The mean ± SD change from baseline in CTX at week 14 was +2.2% ± 43.2%, p = 0.86). Likewise, there was no significant change in NTX/Cr (mean change -2.1%, p = 0.81). Interferon gamma-1b was poorly tolerated. Most subjects had adverse events, and the Mental Health and Mental Component Scales of the SF-36v2 health survey declined slightly (p < 0.05). Over 14 weeks, interferon gamma-1b failed to significantly increase bone turnover markers in ADO2 and was poorly tolerated. Consequently, interferon gamma-1b is unlikely to be effective for decreasing bone mass in ADO2. © 2019 American Society for Bone and Mineral Research.
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Affiliation(s)
- Erik A Imel
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ziyue Liu
- Department of Biostatistics, Indiana University School of Public Health, Indianapolis, IN, USA
| | - Dena Acton
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Melissa Coffman
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Netsanet Gebregziabher
- Department of Biostatistics, Indiana University School of Public Health, Indianapolis, IN, USA
| | - Yan Tong
- Department of Biostatistics, Indiana University School of Public Health, Indianapolis, IN, USA
| | - Michael J Econs
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
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17
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Maurizi A, Capulli M, Curle A, Patel R, Ucci A, Côrtes JA, Oxford H, Lamandé SR, Bateman JF, Rucci N, Teti A. Extra-skeletal manifestations in mice affected by Clcn7-dependent autosomal dominant osteopetrosis type 2 clinical and therapeutic implications. Bone Res 2019; 7:17. [PMID: 31231577 PMCID: PMC6559989 DOI: 10.1038/s41413-019-0055-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 05/10/2019] [Indexed: 12/16/2022] Open
Abstract
Autosomal dominant osteopetrosis type 2 (ADO2) is a high-density brittle bone disease characterized by bone pain, multiple fractures and skeletal-related events, including nerve compression syndrome and hematological failure. We demonstrated that in mice carrying the heterozygous Clcn7G213R mutation, whose human mutant homolog CLCN7G215R affects patients, the clinical impacts of ADO2 extend beyond the skeleton, affecting several other organs. The hallmark of the extra-skeletal alterations is a consistent perivascular fibrosis, associated with high numbers of macrophages and lymphoid infiltrates. Fragmented clinical information in a small cohort of patients confirms extra-skeletal alterations consistent with a systemic disease, in line with the observation that the CLCN7 gene is expressed in many organs. ADO2 mice also show anxiety and depression and their brains exhibit not only perivascular fibrosis but also β-amyloid accumulation and astrogliosis, suggesting the involvement of the nervous system in the pathogenesis of the ADO2 extra-skeletal alterations. Extra-skeletal organs share a similar cellular pathology, confirmed also in vitro in bone marrow mononuclear cells and osteoclasts, characterized by an impairment of the exit pathway of the Clcn7 protein product, ClC7, through the Golgi, with consequent reduced ClC7 expression in late endosomes and lysosomes, associated with high vesicular pH and accumulation of autophagosome markers. Finally, an experimental siRNA therapy, previously proven to counteract the bone phenotype, also improves the extra-skeletal alterations. These results could have important clinical implications, supporting the notion that a systematic evaluation of ADO2 patients for extra-skeletal symptoms could help improve their diagnosis, clinical management, and therapeutic options.
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Affiliation(s)
- Antonio Maurizi
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Mattia Capulli
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Annabel Curle
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Rajvi Patel
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Argia Ucci
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Juliana Alves Côrtes
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Harriet Oxford
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Shireen R Lamandé
- 2Murdoch Children's Research Institute and University of Melbourne, Melbourne, Australia
| | - John F Bateman
- 2Murdoch Children's Research Institute and University of Melbourne, Melbourne, Australia
| | - Nadia Rucci
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Anna Teti
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
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18
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Testing the Cre-mediated genetic switch for the generation of conditional knock-in mice. PLoS One 2019; 14:e0213660. [PMID: 30865697 PMCID: PMC6415906 DOI: 10.1371/journal.pone.0213660] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 02/25/2019] [Indexed: 12/20/2022] Open
Abstract
The Cre-mediated genetic switch combines the ability of Cre recombinase to stably invert or excise a DNA fragment depending upon the orientation of flanking mutant loxP sites. In this work, we have tested this strategy in vivo with the aim to generate two conditional knock-in mice for missense mutations in the Impad1 and Clcn7 genes causing two different skeletal dysplasias. Targeting constructs were generated in which the Impad1 exon 2 and an inverted exon 2* and the Clcn7 exon 7 and an inverted exon 7* containing the point mutations were flanked by mutant loxP sites in a head-to-head orientation. When the Cre recombinase is present, the DNA flanked by the mutant loxP sites is expected to be stably inverted leading to the activation of the mutated exon. The targeting vectors were used to generate heterozygous floxed mice in which inversion of the wild-type with the mutant exon has not occurred yet. To generate knock-in mice, floxed animals were mated to a global Cre-deleter mouse strain for stable inversion and activation of the mutation. Unexpectedly the phenotype of homozygous Impad1 knock-in animals overlaps with the lethal phenotype described previously in Impad1 knock-out mice. Similarly, the phenotype of homozygous Clcn7 floxed mice overlaps with Clcn7 knock-out mice. Expression studies by qPCR and RT-PCR demonstrated that mutant mRNA underwent abnormal splicing leading to the synthesis of non-functional proteins. Thus, the skeletal phenotypes in both murine strains were not caused by the missense mutations, but by aberrant splicing. Our data demonstrate that the Cre mediated genetic switch strategy should be considered cautiously for the generation of conditional knock-in mice.
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19
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Yang Y, Ye W, Guo J, Zhao L, Tu M, Zheng Y, Li L. CLCN7 and TCIRG1 mutations in a single family: Evidence for digenic inheritance of osteopetrosis. Mol Med Rep 2018; 19:595-600. [PMID: 30431110 DOI: 10.3892/mmr.2018.9648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 10/22/2018] [Indexed: 01/26/2023] Open
Abstract
Osteopetrosis is a monogenic condition with various inheritance patterns, including autosomal dominant, autosomal recessive and X‑linked. Several disease‑causing genes have been identified and three distinguished types of osteopetrosis have been reported. In the present study, a family with osteopetrosis was investigated. Two novel mutations in chloride voltage‑gated channel 7 (CLCN7) and T cell immune regulator 1 (TCIRG1) were identified by exome sequencing, Sanger sequencing and microsatellite marker analysis. The CLCN7 mutation occurred in amino acid R286, the same position as previously reported. The TCIRG1 mutation occurred on a splicing site of exon 15, thereby leading to a truncated transcript. These two mutations were undetected in 496 ethnic‑matched controls. To the best of our knowledge, this is the first report of human osteopetrosis involving digenic inheritance in a single family, which has important implications for decisions on clinical therapeutic regimen, prognosis evaluation and antenatal diagnosis.
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Affiliation(s)
- Yongjia Yang
- The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute (HCRI), Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
| | - Weihua Ye
- The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute (HCRI), Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
| | - Jihong Guo
- The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute (HCRI), Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
| | - Liu Zhao
- The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute (HCRI), Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
| | - Ming Tu
- The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute (HCRI), Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
| | - Yu Zheng
- The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute (HCRI), Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
| | - Liping Li
- The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute (HCRI), Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
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Jentsch TJ, Pusch M. CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease. Physiol Rev 2018; 98:1493-1590. [DOI: 10.1152/physrev.00047.2017] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.
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Affiliation(s)
- Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
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21
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Maurizi A, Capulli M, Patel R, Curle A, Rucci N, Teti A. RNA interference therapy for autosomal dominant osteopetrosis type 2. Towards the preclinical development. Bone 2018; 110:343-354. [PMID: 29501587 DOI: 10.1016/j.bone.2018.02.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 02/12/2018] [Accepted: 02/27/2018] [Indexed: 12/18/2022]
Abstract
Autosomal Dominant Osteopetrosis type 2 (ADO2) is a rare bone disease characterized by dense and brittle bones due to impairment of osteoclast bone resorption. Dominant negative mutations of the CLCN7 gene affect about 70% of ADO2 patients. ADO2 has no cure and our recent work established that it is suitable for gene silencing by a specific small interfering RNA that does not affect the normal mRNA, thus inducing a condition of pseudo-haplosufficiency and rescuing the bone phenotype. We performed a systematic study to test the likelihood that the therapy could progress towards clinical trials, treating Clcn7G213R/WT ADO2 mice with Clcn7G213R-specific siRNA and investigating the bone phenotype by μCT and histomorphometry, and safety, by histopathology and serology. We demonstrated that our Clcn7G213R siRNA is not only effective in pre-pubertal ADO2 male mice as we showed in our previous study, but also in adult and ageing mice, in males and females, by intraperitoneal and subcutaneous administration. Furthermore, the study also showed safety following prolonged chronic administration and allowed us to identify specific end-points to be potentially used in clinical trials. These results may pave the way towards regulatory toxicity studies, through which the therapy, that is patent-protected, can obtain approval from public health authorities for the transition to the Phase I/II clinical trials. The study also suggests that similar strategies could be applied to other autosomal dominant bone diseases, opening an avenue for a wider use of the RNA interference therapy in rare genetic disorders.
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Affiliation(s)
- Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio - Coppito 2, 67100 L'Aquila, Italy
| | - Mattia Capulli
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio - Coppito 2, 67100 L'Aquila, Italy
| | - Rajvi Patel
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio - Coppito 2, 67100 L'Aquila, Italy
| | - Annabel Curle
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio - Coppito 2, 67100 L'Aquila, Italy
| | - Nadia Rucci
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio - Coppito 2, 67100 L'Aquila, Italy
| | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Via Vetoio - Coppito 2, 67100 L'Aquila, Italy.
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22
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Caetano-Lopes J, Lessard SG, Hann S, Espinoza K, Kang KS, Lim KE, Horan DJ, Noonan HR, Hu D, Baron R, Robling AG, Warman ML. Clcn7 F318L/+ as a new mouse model of Albers-Schönberg disease. Bone 2017; 105:253-261. [PMID: 28942122 PMCID: PMC5752150 DOI: 10.1016/j.bone.2017.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/08/2017] [Accepted: 09/15/2017] [Indexed: 12/21/2022]
Abstract
Dominant negative mutations in CLCN7, which encodes a homodimeric chloride channel needed for matrix acidification by osteoclasts, cause Albers-Schönberg disease (also known as autosomal dominant osteopetrosis type 2). More than 25 different CLCN7 mutations have been identified in patients affected with Albers-Schönberg disease, but only one mutation (Clcn7G213R) has been introduced in mice to create an animal model of this disease. Here we describe a mouse with a different osteopetrosis-causing mutation (Clcn7F318L). Compared to Clcn7+/+ mice, 12-week-old Clcn7F318L/+ mice have significantly increased trabecular bone volume, consistent with Clcn7F318L acting as a dominant negative mutation. Clcn7F318L/F318L and Clcn7F318L/G213R mice die by 1month of age and resemble Clcn7 knockout mice, which indicate that p.F318L mutant protein is non-functional and p.F318L and p.G213R mutant proteins do not complement one another. Since it has been reported that treatment with interferon gamma (IFN-G) improves bone properties in Clcn7G213R/+ mice, we treated Clcn7F318L/+ mice with IFN-G and observed a decrease in osteoclast number and mineral apposition rate, but no overall improvement in bone properties. Our results suggest that the benefits of IFN-G therapy in patients with Albers-Schönberg disease may be mutation-specific.
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Affiliation(s)
- J Caetano-Lopes
- Orthopaedic Research Laboratories, Boston Children's Hospital, Boston, MA, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - S G Lessard
- Orthopaedic Research Laboratories, Boston Children's Hospital, Boston, MA, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - S Hann
- Orthopaedic Research Laboratories, Boston Children's Hospital, Boston, MA, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - K Espinoza
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA
| | - K S Kang
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - K E Lim
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - D J Horan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - H R Noonan
- BBS Program, Harvard Medical School, Boston, MA, USA
| | - D Hu
- Division of Bone and Mineral Research, Harvard School of Dental Medicine, Boston, MA, USA
| | - R Baron
- Division of Bone and Mineral Research, Harvard School of Dental Medicine, Boston, MA, USA
| | - A G Robling
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - M L Warman
- Orthopaedic Research Laboratories, Boston Children's Hospital, Boston, MA, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.
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23
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Teti A, Econs MJ. Osteopetroses, emphasizing potential approaches to treatment. Bone 2017; 102:50-59. [PMID: 28167345 DOI: 10.1016/j.bone.2017.02.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 02/02/2017] [Accepted: 02/02/2017] [Indexed: 12/22/2022]
Abstract
Osteopetroses are a heterogeneous group of rare genetic bone diseases sharing the common hallmarks of reduced osteoclast activity, increased bone mass and high bone fragility. Osteoclasts are bone resorbing cells that contribute to bone growth and renewal through the erosion of the mineralized matrix. Alongside the bone forming activity by osteoblasts, osteoclasts allow the skeleton to grow harmonically and maintain a healthy balance between bone resorption and formation. Osteoclast impairment in osteopetroses prevents bone renewal and deteriorates bone quality, causing atraumatic fractures. Osteopetroses vary in severity and are caused by mutations in a variety of genes involved in bone resorption or in osteoclastogenesis. Frequent signs and symptoms include osteosclerosis, deformity, dwarfism and narrowing of the bony canals, including the nerve foramina, leading to hematological and neural failures. The disease is autosomal, with only one extremely rare form associated so far to the X-chromosome, and can have either recessive or dominant inheritance. Recessive ostepetroses are generally lethal in infancy or childhood, with a few milder forms clinically denominated intermediate osteopetroses. Dominant osteopetrosis is so far associated only with mutations in the CLCN7 gene and, although described as a benign form, it can be severely debilitating, although not at the same level as recessive forms, and can rarely result in reduced life expectancy. Severe osteopetroses due to osteoclast autonomous defects can be treated by Hematopoietic Stem Cell Transplant (HSCT), but those due to deficiency of the pro-osteoclastogenic cytokine, RANKL, are not suitable for this procedure. Likewise, it is unclear as to whether HSCT, which has high intrinsic risks, results in clinical improvement in autosomal dominant osteopetrosis. Therefore, there is an unmet medical need to identify new therapies and studies are currently in progress to test gene and cell therapies, small interfering RNA approach and novel pharmacologic treatments.
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Affiliation(s)
- Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, via Vetoio-Coppito 2, 67100 L'Aquila, Italy.
| | - Michael J Econs
- Department of Medicine, Indiana University, 1120 W. Michigan St., Indianapolis, IN 46202, USA; Department of Medical and Molecular Genetics, Indiana University, 1120 W. Michigan St., Indianapolis, IN 46202, USA.
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24
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Foote JR, Behe P, Frampton M, Levine AP, Segal AW. An Exploration of Charge Compensating Ion Channels across the Phagocytic Vacuole of Neutrophils. Front Pharmacol 2017; 8:94. [PMID: 28293191 PMCID: PMC5329019 DOI: 10.3389/fphar.2017.00094] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/13/2017] [Indexed: 11/13/2022] Open
Abstract
Neutrophils phagocytosing bacteria and fungi exhibit a burst of non-mitochondrial respiration that is required to kill and digest the engulfed microbes. This respiration is accomplished by the movement of electrons across the wall of the phagocytic vacuole by the neutrophil NADPH oxidase, NOX2. In this study, we have attempted to identify the non-proton ion channels or transporters involved in charge compensation by examining the effect of inhibitors on vacuolar pH and cross-sectional area, and on oxygen consumption. The chloride channel inhibitors 4-[(2-Butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid (DCPIB) and flufenamic acid (FFA) were the most effective inhibitors of alkalinisation in human neutrophil vacuoles, suggesting an efflux of chloride from the vacuole. The proton channel inhibitor, zinc (Zn2+), combined with DCPIB caused more vacuolar swelling than either compound alone, suggesting the conductance of osmotically active cations into the vacuole. Support for cation influx was provided by the broad-spectrum cation transport inhibitors anandamide and quinidine which inhibited vacuolar alkalinisation and swelling when applied with zinc. Oxygen consumption was generally unaffected by these anion or cation inhibitors alone, but when combined with Zn2+ it was dramatically reduced, suggesting that multiple channels in combination can compensate the charge. In an attempt to identify specific channels, we tested neutrophils from knock-out mouse models including CLIC1, ClC3, ClC4, ClC7, KCC3, KCNQ1, KCNE3, KCNJ15, TRPC1/3/5/6, TRPA1/TRPV1, TRPM2, and TRPV2, and double knockouts of CLIC1, ClC3, KCC3, TRPM2, and KCNQ1 with HVCN1, and humans with channelopathies involving BEST1, ClC7, CFTR, and MCOLN1. No gross abnormalities in vacuolar pH or area were found in any of these cells suggesting that we had not tested the correct channel, or that there is redundancy in the system. The respiratory burst was suppressed in the KCC3-/- and enhanced in the CLIC1-/- cells, but was normal in all others, including ClC3-/-. These results suggest charge compensation by a chloride conductance out of the vacuole and by cation/s into it. The identity of these channels remains to be established.
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Affiliation(s)
- Juliet R Foote
- Division of Medicine, Centre for Molecular Medicine, University College London London, UK
| | - Philippe Behe
- Division of Medicine, Centre for Molecular Medicine, University College London London, UK
| | - Mathew Frampton
- Division of Medicine, Centre for Molecular Medicine, University College London London, UK
| | - Adam P Levine
- Division of Medicine, Centre for Molecular Medicine, University College London London, UK
| | - Anthony W Segal
- Division of Medicine, Centre for Molecular Medicine, University College London London, UK
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25
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Alam I, McQueen AK, Acton D, Reilly AM, Gerard-O'Riley RL, Oakes DK, Kasipathi C, Huffer A, Wright WB, Econs MJ. Phenotypic severity of autosomal dominant osteopetrosis type II (ADO2) mice on different genetic backgrounds recapitulates the features of human disease. Bone 2017; 94:34-41. [PMID: 27746321 DOI: 10.1016/j.bone.2016.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 10/20/2022]
Abstract
Autosomal dominant osteopetrosis type II (ADO2) is a heritable osteosclerotic bone disorder due to dysfunctional osteoclast activity. ADO2 is caused by missense mutations in the chloride channel 7 (CLCN7) gene characterized by osteosclerosis with multiple fractures. ADO2 can result in osteomyelitis, visual loss and bone marrow failure. Currently, there is no cure for ADO2, and until recently no appropriate animal model of ADO2 existed to understand better the pathogenesis of this disease and to test new therapies. Therefore, we created ADO2 knock-in mouse model with a G213R (human homolog of G215R) missense mutation in the Clcn7 gene on 129S1 background, and demonstrated that this mouse model phenocopies human ADO2. As ADO2 gives rise to incomplete penetrance (66%) in human and marked phenotypic variability is observed among patients with the same mutation, we hypothesized that the severity and penetrance of ADO2 will also vary in mouse models on different genetic backgrounds. To test this, we created ADO2 mouse models in DBA/D2, C57BL/6J/B6 and Balb/c strains, and compared bone phenotypes and performed serum biochemical analysis between strain- and age-matched wild-type (WT) and ADO2 mice. At 3months of age, whole body aBMD was higher (4-7% in male; 1-5% in female) in the ADO2 mice compared to their wild-type littermates. In addition, ADO2 male mice on 129 background displayed highest percent increase of BV/TV (106%), followed by D2 (92%), B6 (46%), and Balb/c (33%) compared to strain-matched wild-type mice. We observed similar differences for BV/TV between ADO2 and wild-type mice on different genetic backgrounds in female: 129 (96%)>D2 (73%)>Balb/c (39%) and B6 (36%). Serum calcium, phosphorus, alkaline phosphatase and P1NP levels were similar in the WT and ADO2 mice on all genetic backgrounds but TRAP was higher (76% to 220% in male; 33-95% in female) and CTX/TRAP ratio was lower (39-65% in male and 3-41% in female) in the ADO2 mice compared to their strain-matched wild-type littermates. We also found that young (3months) ADO2 mice on 129S1 background exhibited 200% higher trabecular BV/TV whereas old (18months) ADO2 mice displayed 400-700% higher BV/TV compared to their age-matched wild-type controls. In summary, phenotypic severity in ADO2 mice varied markedly on different genetic backgrounds (129>D2>Balb/c>B6) and became more pronounced with age, which resembles the wide variations in phenotype observed in ADO2 patients. These mouse models will help us to identify genes/factors that influence severity and penetrance of ADO2, and test innovative therapies to treat this disease.
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Affiliation(s)
- Imranul Alam
- Medicine, Indiana University School of Medicine, IN, USA.
| | - Amie K McQueen
- Medicine, Indiana University School of Medicine, IN, USA
| | - Dena Acton
- Medicine, Indiana University School of Medicine, IN, USA
| | | | | | - Dana K Oakes
- Medicine, Indiana University School of Medicine, IN, USA
| | | | - Abigail Huffer
- Medicine, Indiana University School of Medicine, IN, USA
| | | | - Michael J Econs
- Medicine, Indiana University School of Medicine, IN, USA; Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
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26
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Chen X, Zhang K, Hock J, Wang C, Yu X. Enhanced but hypofunctional osteoclastogenesis in an autosomal dominant osteopetrosis type II case carrying a c.1856C>T mutation in CLCN7. Bone Res 2016; 4:16035. [PMID: 27990310 PMCID: PMC5126728 DOI: 10.1038/boneres.2016.35] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 08/03/2016] [Accepted: 08/25/2016] [Indexed: 02/05/2023] Open
Abstract
Type II autosomal dominant osteopetrosis (ADO2), which is the most common form of osteopetrosis, is caused by heterozygous mutations in the chloride channel 7 (CLCN7) gene. The osteopetrosis of ADO2 has been attributed to hypofunctional osteoclasts. The mechanism underlying the abnormality in osteoclast function remains largely unknown. This study was designed to investigate gene mutations and osteoclast function in a case that was clinically diagnosed as ADO2. Genomic DNA was extracted from blood samples of this patient, and the 25 exons of CLCN7 were amplified. Peripheral blood from the ADO2 subject and a healthy age- and sex-matched control was used to evaluate osteoclastogenesis, osteoclast morphology, and bone resorption. Analysis of DNA from the patient showed a germline heterozygous missense mutation, c.1856C>T (p.P619L), in exon 20 of CLCN7. A similar homozygous mutation at this site was previously reported in a patient with autosomal recessive osteopetrosis. When cultured, the peripheral blood mononuclear cells (PBMCs) from the ADO2 patient spontaneously differentiated into mature osteoclasts in vitro. The ADO2 patient’s PBMCs formed enhanced, but heterogeneous, osteoclasts in both the presence and absence of macrophage-colony stimulating factor, and nuclear factor-ĸB ligand. Bone resorption was reduced in the ADO2 patient’s osteoclasts, which exhibited aberrant morphology and abnormal distribution of integrin avβ3. Gene analysis found increased c-fos expression and reduced RhoA and integrin beta 3 expression in ADO2 cells. In conclusion, our data suggest that enhanced, heterogeneous osteoclast induction may be an intrinsic characteristic of ADO2.
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Affiliation(s)
- Xiang Chen
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University , Chengdu, China
| | - Kun Zhang
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University , Chengdu, China
| | - Janet Hock
- The Polis Center, Indiana University-Purdue University Indianapolis , Indianapolis, IN, USA
| | - Chunyu Wang
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University , Chengdu, China
| | - Xijie Yu
- Laboratory of Endocrinology and Metabolism, Department of Endocrinology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University , Chengdu, China
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27
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Piret SE, Gorvin CM, Trinh A, Taylor J, Lise S, Taylor JC, Ebeling PR, Thakker RV. Autosomal dominant osteopetrosis associated with renal tubular acidosis is due to a CLCN7 mutation. Am J Med Genet A 2016; 170:2988-2992. [PMID: 27540713 PMCID: PMC5132132 DOI: 10.1002/ajmg.a.37755] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 04/21/2016] [Indexed: 12/16/2022]
Abstract
The aim of this study was to identify the causative mutation in a family with an unusual presentation of autosomal dominant osteopetrosis (OPT), proximal renal tubular acidosis (RTA), renal stones, epilepsy, and blindness, a combination of features not previously reported. We undertook exome sequencing of one affected and one unaffected family member, followed by targeted analysis of known candidate genes to identify the causative mutation. This identified a missense mutation (c.643G>A; p.Gly215Arg) in the gene encoding the chloride/proton antiporter 7 (gene CLCN7, protein CLC‐7), which was confirmed by amplification refractory mutation system (ARMS)‐PCR, and to be present in the three available patients. CLC‐7 mutations are known to cause autosomal dominant OPT type 2, also called Albers–Schonberg disease, which is characterized by osteosclerosis, predominantly of the spine, pelvis and skull base, resulting in bone fragility and fractures. Albers–Schonberg disease is not reported to be associated with RTA, but autosomal recessive OPT type 3 (OPTB3) with RTA is associated with carbonic anhydrase type 2 (CA2) mutations. No mutations were detected in CA2 or any other genes known to cause proximal RTA. Neither CLCN7 nor CA2 mutations have previously been reported to be associated with renal stones or epilepsy. Thus, we identified a CLCN7 mutation in a family with autosomal dominant osteopetrosis, RTA, renal stones, epilepsy, and blindness. © 2016 The Authors. American Journal of Medical Genetics Part A Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Sian E Piret
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Caroline M Gorvin
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Anne Trinh
- Faculty of Medicine, Nursing and Health Sciences, Department of Medicine, School of Clinical Sciences, Monash Medical Centre, Monash University, Clayton, Victoria, Australia
| | - John Taylor
- Oxford Medical Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford, United Kingdom
| | - Stefano Lise
- Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
- Oxford NIHR Comprehensive Biomedical Research Centre, Oxford, United Kingdom
| | - Jenny C Taylor
- Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
- Oxford NIHR Comprehensive Biomedical Research Centre, Oxford, United Kingdom
| | - Peter R Ebeling
- Faculty of Medicine, Nursing and Health Sciences, Department of Medicine, School of Clinical Sciences, Monash Medical Centre, Monash University, Clayton, Victoria, Australia
| | - Rajesh V Thakker
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Oxford, United Kingdom.
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28
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Deng H, He D, Rong P, Xu H, Yuan L, Li L, Lu Q, Guo Y. Novel CLCN7 mutation identified in a Han Chinese family with autosomal dominant osteopetrosis-2. Mol Pain 2016; 12:12/0/1744806916652628. [PMID: 27325559 PMCID: PMC4955969 DOI: 10.1177/1744806916652628] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/06/2016] [Indexed: 12/25/2022] Open
Abstract
Osteopetrosis is a heritable bone condition featuring increased bone density due to defective osteoclastic bone resorption. Exome sequencing and Sanger sequencing were conducted in Han Chinese family members, some of whom had typical osteopetrosis, and a novel missense variant c.2350A>T (p.R784W) in the chloride channel 7 gene (CLCN7) was identified. This variant cosegregated with the disorder in the family but was not observed in 800 controls. The data indicate that exome sequencing is a powerful and effective molecular diagnostic tool for detecting mutations in osteopetrosis, which is a genetically and clinically heterogeneous disorder. This discovery broadens the CLCN7 gene mutation spectrum and has important implications for clinical therapeutic regimen decisions, prognosis evaluations, and antenatal diagnoses.
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Affiliation(s)
- Hao Deng
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
- Department of Neurology, the Third Xiangya Hospital, Central South University, Changsha, China
- Hao Deng, the Third Xiangya Hospital, Central South University, 138 Tongzipo Road, Changsha, Hunan 410013, China. Yi Guo, Department of Medical Information, Information Security and Big Data Research Institute, Central South University, 172 Tongzipo Road, Changsha, Hunan 410013, China.
| | - Dan He
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Pengfei Rong
- Department of Radiology, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Hongbo Xu
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Lamei Yuan
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Liu Li
- Department of Pediatrics, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Qian Lu
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
| | - Yi Guo
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, China
- Department of Medical Information, Information Security and Big Data Research Institute, Central South University, Changsha, China
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Alam I, Gray AK, Acton D, Gerard-O'Riley RL, Reilly AM, Econs MJ. Interferon Gamma, but not Calcitriol Improves the Osteopetrotic Phenotypes in ADO2 Mice. J Bone Miner Res 2015; 30:2005-13. [PMID: 25943708 DOI: 10.1002/jbmr.2545] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/23/2015] [Accepted: 04/27/2015] [Indexed: 02/02/2023]
Abstract
ADO2 is a heritable osteosclerotic disorder that usually results from heterozygous missense dominant negative mutations in the chloride channel 7 gene (CLCN7). ADO2 is characterized by a wide range of features and severity, including multiple fractures, impaired vision due to secondary bony overgrowth and/or the lack of the optical canal enlargement with growth, and osteonecrosis/osteomyelitis. The disease is presently incurable, although anecdotal evidence suggests that calcitriol and interferon gamma-1b (IFN-G) may have some beneficial effects. To identify the role of these drugs for the treatment of ADO2, we utilized a knock-in (G213R mutation in Clcn7) ADO2 mouse model that resembles the human disease. Six-week-old ADO2 heterozygous mice were administered vehicle (PBS) or calcitriol or IFN-G 5 times per week for 8 weeks. We determined bone phenotypes using DXA and μCT, and analyzed serum biochemistry and bone resorption markers. ADO2 mice treated with all doses of IFN-G significantly (p<0.05) attenuated the increase of whole body aBMD and distal femur BV/TV gain in both male and female compared to the vehicle group. In contrast, mice treated with low and medium doses of calcitriol showed a trend of higher aBMD and BV/TV whereas high dose calcitriol significantly (p<0.05) increased bone mass compared to the vehicle group. The calcium and phosphorus levels did not differ between vehicle and IFN-G or calcitriol treated mice; however, we detected significantly (p<0.05) elevated levels of CTX/TRAP5b ratio in IFN-G treated mice. Our findings indicate that while IFN-G at all doses substantially improved the osteopetrotic phenotypes in ADO2 heterozygous mice, calcitriol treatment at any dose did not improve the phenotype and at high dose further increased bone mass. Thus, use of high dose calcitriol therapy in ADO2 patients merits serious reconsideration. Importantly, our data support the prospect of a clinical trial of IFN-G in ADO2 patients.
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Affiliation(s)
- Imranul Alam
- Medicine, Indiana University School of Medicine, IN, USA
| | - Amie K Gray
- Medicine, Indiana University School of Medicine, IN, USA
| | - Dena Acton
- Medicine, Indiana University School of Medicine, IN, USA
| | | | | | - Michael J Econs
- Medicine, Indiana University School of Medicine, IN, USA.,Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
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Effective Small Interfering RNA Therapy to Treat CLCN7-dependent Autosomal Dominant Osteopetrosis Type 2. MOLECULAR THERAPY. NUCLEIC ACIDS 2015; 4:e248. [PMID: 26325626 PMCID: PMC4877447 DOI: 10.1038/mtna.2015.21] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/15/2015] [Indexed: 01/14/2023]
Abstract
In about 70% of patients affected by autosomal dominant osteopetrosis type 2 (ADO2), osteoclast activity is reduced by heterozygous mutations of the CLCN7 gene, encoding the ClC-7 chloride/hydrogen antiporter. CLCN7(G215R)-, CLCN7(R767W)-, and CLCN7(R286W)-specific siRNAs silenced transfected mutant mRNA/EGFP in HEK293 cells, in RAW264.7 cells and in human osteoclasts, with no change of CLCN7(WT) mRNA and no effect of scrambled siRNA on the mutant transcripts. Osteoclasts from Clcn7(G213R) ADO2 mice showed reduced bone resorption, a condition rescued by Clcn7(G213R)-specific siRNA. Treatment of ADO2 mice with Clcn7(G213R)-specific siRNA induced increase of bone resorption variables and decrease of trabecular bone mass, leading to an overall improvement of the osteopetrotic bone phenotype. Treatment did not induce overt adverse effects and was effective also with siRNAs specific for other mutants. These results demonstrate that a siRNA-based experimental treatment of ADO2 is feasible, and underscore a translational impact for future strategy to cure this therapeutically neglected form of osteopetrosis.
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Brommage R, Liu J, Hansen GM, Kirkpatrick LL, Potter DG, Sands AT, Zambrowicz B, Powell DR, Vogel P. High-throughput screening of mouse gene knockouts identifies established and novel skeletal phenotypes. Bone Res 2014; 2:14034. [PMID: 26273529 PMCID: PMC4472125 DOI: 10.1038/boneres.2014.34] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 12/13/2022] Open
Abstract
Screening gene function in vivo is a powerful approach to discover novel drug targets. We present high-throughput screening (HTS) data for 3 762 distinct global gene knockout (KO) mouse lines with viable adult homozygous mice generated using either gene-trap or homologous recombination technologies. Bone mass was determined from DEXA scans of male and female mice at 14 weeks of age and by microCT analyses of bones from male mice at 16 weeks of age. Wild-type (WT) cagemates/littermates were examined for each gene KO. Lethality was observed in an additional 850 KO lines. Since primary HTS are susceptible to false positive findings, additional cohorts of mice from KO lines with intriguing HTS bone data were examined. Aging, ovariectomy, histomorphometry and bone strength studies were performed and possible non-skeletal phenotypes were explored. Together, these screens identified multiple genes affecting bone mass: 23 previously reported genes (Calcr, Cebpb, Crtap, Dcstamp, Dkk1, Duoxa2, Enpp1, Fgf23, Kiss1/Kiss1r, Kl (Klotho), Lrp5, Mstn, Neo1, Npr2, Ostm1, Postn, Sfrp4, Slc30a5, Slc39a13, Sost, Sumf1, Src, Wnt10b), five novel genes extensively characterized (Cldn18, Fam20c, Lrrk1, Sgpl1, Wnt16), five novel genes with preliminary characterization (Agpat2, Rassf5, Slc10a7, Slc26a7, Slc30a10) and three novel undisclosed genes coding for potential osteoporosis drug targets.
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Affiliation(s)
| | - Jeff Liu
- Lexicon Pharmaceuticals , The Woodlands, TX, USA
| | | | | | | | | | | | | | - Peter Vogel
- Lexicon Pharmaceuticals , The Woodlands, TX, USA
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Capulli M, Olstad OK, Onnerfjord P, Tillgren V, Muraca M, Gautvik KM, Heinegård D, Rucci N, Teti A. The C-terminal domain of chondroadherin: a new regulator of osteoclast motility counteracting bone loss. J Bone Miner Res 2014; 29:1833-46. [PMID: 24616121 DOI: 10.1002/jbmr.2206] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 01/23/2014] [Accepted: 02/06/2014] [Indexed: 11/12/2022]
Abstract
Chondroadherin (CHAD) is a leucine-rich protein promoting cell attachment through binding to integrin α2 β1 and syndecans. We observed that CHAD mRNA and protein were lower in bone biopsies of 50-year-old to 65-year-old osteoporotic women and in bone samples of ovariectomized mice versus gender/age-matched controls, suggesting a role in bone metabolism. By the means of an internal cyclic peptide (cyclicCHAD), we observed that its integrin binding sequence impaired preosteoclast migration through a nitric oxide synthase 2-dependent mechanism, decreasing osteoclastogenesis and bone resorption in a concentration-dependent fashion, whereas it had no effect on osteoblasts. Consistently, cyclicCHAD reduced transcription of two nitric oxide downstream genes, migfilin and vasp, involved in cell motility. Furthermore, the nitric oxide donor, S-nitroso-N-acetyl-D,L-penicillamine, stimulated preosteoclast migration and prevented the inhibitory effect of cyclicCHAD. Conversely, the nitric oxide synthase 2 (NOS2) inhibitor, N5-(1-iminoethyl)-l-ornithine, decreased both preosteoclast migration and differentiation, confirming a role of the nitric oxide pathway in the mechanism of action triggered by cyclicCHAD. In vivo, administration of cyclicCHAD was well tolerated and increased bone volume in healthy mice, with no adverse effect. In ovariectomized mice cyclicCHAD improved bone mass by both a preventive and a curative treatment protocol, with an effect in line with that of the bisphosphonate alendronate, that was mimicked by the NOS2 inhibitor [L-N6-(1-Iminoethyl)-lysine.2 dihydrochloride]. In both mouse models, cyclicCHAD reduced osteoclast and bone resorption without affecting osteoblast parameters and bone formation. In conclusion, CHAD is a novel regulator of bone metabolism that, through its integrin binding domain, inhibits preosteoclast motility and bone resorption, with a potential translational impact for the treatment of osteoporosis.
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Affiliation(s)
- Mattia Capulli
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
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