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Martineau C, Naja RP, Husseini A, Hamade B, Kaufmann M, Akhouayri O, Arabian A, Jones G, St-Arnaud R. Optimal bone fracture repair requires 24R,25-dihydroxyvitamin D3 and its effector molecule FAM57B2. J Clin Invest 2018; 128:3546-3557. [PMID: 30010626 DOI: 10.1172/jci98093] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 05/08/2018] [Indexed: 12/18/2022] Open
Abstract
The biological activity of 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3] remains controversial, but it has been suggested that it contributes to fracture healing. Cyp24a1-/- mice, synthesizing no 24R,25(OH)2D3, show suboptimal endochondral ossification during fracture repair, with smaller callus and reduced stiffness. These defects were corrected by 24R,25(OH)2D3 treatment, but not by 1,25-dihydroxyvitamin D3. Microarrays with Cyp24a1-/- callus mRNA identified FAM57B2 as a mediator of the 24R,25(OH)2D3 effect. FAM57B2 produced lactosylceramide (LacCer) upon specific binding of 24R,25(OH)2D3. Fam57b inactivation in chondrocytes (Col2-Cre Fam57bfl/fl) phenocopied the callus formation defect of Cyp24a1-/- mice. LacCer or 24R,25(OH)2D3 injections restored callus volume, stiffness, and mineralized cartilage area in Cyp24a1-null mice, but only LacCer rescued Col2-Cre Fam57bfl/fl mice. Gene expression in callus tissue suggested that the 24R,25(OH)2D3/FAM57B2 cascade affects cartilage maturation. We describe a previously unrecognized pathway influencing endochondral ossification during bone repair through LacCer production upon binding of 24R,25(OH)2D3 to FAM57B2. Our results identify potential new approaches to ameliorate fracture healing.
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Affiliation(s)
- Corine Martineau
- Research Centre, Shriners Hospitals for Children - Canada, Montreal, Quebec, Canada
| | - Roy Pascal Naja
- Research Centre, Shriners Hospitals for Children - Canada, Montreal, Quebec, Canada.,Department of Human Genetics, and
| | - Abdallah Husseini
- Research Centre, Shriners Hospitals for Children - Canada, Montreal, Quebec, Canada.,Department of Surgery, McGill University, Montreal, Quebec, Canada
| | - Bachar Hamade
- Research Centre, Shriners Hospitals for Children - Canada, Montreal, Quebec, Canada.,Department of Surgery, McGill University, Montreal, Quebec, Canada
| | - Martin Kaufmann
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Omar Akhouayri
- Research Centre, Shriners Hospitals for Children - Canada, Montreal, Quebec, Canada
| | - Alice Arabian
- Research Centre, Shriners Hospitals for Children - Canada, Montreal, Quebec, Canada
| | - Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - René St-Arnaud
- Research Centre, Shriners Hospitals for Children - Canada, Montreal, Quebec, Canada.,Department of Human Genetics, and.,Department of Surgery, McGill University, Montreal, Quebec, Canada.,Department of Medicine, McGill University, Montreal, Quebec, Canada.,Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
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Abstract
PURPOSE OF REVIEW In addition to the actions of the endocrine hormone, 1alpha,25-dihydroxyvitamin D (1,25(OH)2D) in stimulating intestinal calcium absorption, the regulation of bone mineral metabolism by 1,25(OH)2D is also considered an important contributor to calcium homeostasis. However, recent evidence suggest that 1,25(OH)2D acting either via endocrine or autocrine pathways plays varied roles in bone, which suggests that vitamin D contributes to the maintenance of bone mineral in addition to its catabolic roles. This review highlights the contrasting evidence for the direct action for vitamin D metabolism and activity in bone. RECENT FINDINGS Numerous cells within bone express vitamin D receptor (VDR), synthesise and catabolise 1,25(OH)2D via 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1), and 25-hydroxyvitamin D 24-hydroxylase (CYP24A1) enzymes, respectively. Recent evidence suggests that all three genes are required to regulate processes of bone resorption, mineralization and fracture repair. The actions of vitamin D in bone appear to negatively or positively regulate bone mineral depending on the physiological and pathological circumstances, suggesting that vitamin D plays pleiotropic roles in bone.
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Affiliation(s)
- Paul H Anderson
- Musculoskeletal Biology Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, 5001, Australia.
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