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Yoshida T, Kanegane H, Osato M, Yanagida M, Miyawaki T, Ito Y, Shigesada K. Functional analysis of RUNX2 mutations in Japanese patients with cleidocranial dysplasia demonstrates novel genotype-phenotype correlations. Am J Hum Genet 2002; 71:724-38. [PMID: 12196916 PMCID: PMC378531 DOI: 10.1086/342717] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2002] [Accepted: 06/25/2002] [Indexed: 12/18/2022] Open
Abstract
Cleidocranial dysplasia (CCD) is an autosomal dominant heritable skeletal disease caused by heterozygous mutations in the osteoblast-specific transcription factor RUNX2. We have performed mutational analysis of RUNX2 on 24 unrelated patients with CCD. In 17 patients, 16 distinct mutations were detected in the coding region of RUNX2: 4 frameshift, 3 nonsense, 6 missense, and 2 splicing mutations, in addition to 1 polymorphism. The missense mutations were all clustered within the Runt domain, and their protein products were severely impaired in DNA binding and transactivation. In contrast, two RUNX2 mutants had the Runt domain intact and remained partially competent for transactivation. One criterion of CCD, short stature, was much milder in the patients with the intact Runt domain than in those without. Furthermore, a significant correlation was found between short stature and the number of supernumerary teeth. On the one hand, these genotype-phenotype correlations highlight a general, quantitative dependency, by skeleto-dental developments, on the gene dosage of RUNX2, which has hitherto been obscured by extreme clinical diversities of CCD; this gene-dosage effect is presumed to manifest on small reductions in the total RUNX2 activity, by approximately one-fourth of the normal level at minimum. On the other hand, the classic CCD phenotype, hypoplastic clavicles or open fontanelles, was invariably observed in all patients, including those with normal height. Thus, the cleidocranial bone formation, as mediated by intramembranous ossification, may require a higher level of RUNX2 than does skeletogenesis (mediated by endochondral ossification), as well as odontogenesis (involving still different complex processes). Overall, these results suggest that CCD could result from much smaller losses in the RUNX2 function than has been envisioned on the basis of the conventional haploinsufficiency model.
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Affiliation(s)
- Taketoshi Yoshida
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan; and Departments of Genetics and Molecular Biology and Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto
| | - Hirokazu Kanegane
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan; and Departments of Genetics and Molecular Biology and Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto
| | - Motomi Osato
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan; and Departments of Genetics and Molecular Biology and Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto
| | - Masatoshi Yanagida
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan; and Departments of Genetics and Molecular Biology and Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto
| | - Toshio Miyawaki
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan; and Departments of Genetics and Molecular Biology and Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto
| | - Yoshiaki Ito
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan; and Departments of Genetics and Molecular Biology and Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto
| | - Katsuya Shigesada
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan; and Departments of Genetics and Molecular Biology and Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto
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202
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Zhang X, Kuroda S, Carpenter D, Nishimura I, Soo C, Moats R, Iida K, Wisner E, Hu FY, Miao S, Beanes S, Dang C, Vastardis H, Longaker M, Tanizawa K, Kanayama N, Saito N, Ting K. Craniosynostosis in transgenic mice overexpressing Nell-1. J Clin Invest 2002; 110:861-70. [PMID: 12235118 PMCID: PMC151127 DOI: 10.1172/jci15375] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2002] [Accepted: 07/16/2002] [Indexed: 11/17/2022] Open
Abstract
Previously, we reported NELL-1 as a novel molecule overexpressed during premature cranial suture closure in patients with craniosynostosis (CS), one of the most common congenital craniofacial deformities. Here we describe the creation and analysis of transgenic mice overexpressing Nell-1. Nell-1 transgenic animals exhibited CS-like phenotypes that ranged from simple to compound synostoses. Histologically, the osteogenic fronts of abnormally closing/closed sutures in these animals revealed calvarial overgrowth and overlap along with increased osteoblast differentiation and reduced cell proliferation. Furthermore, anomalies were restricted to calvarial bone, despite generalized, non-tissue-specific overexpression of Nell-1. In vitro, Nell-1 overexpression accelerated calvarial osteoblast differentiation and mineralization under normal culture conditions. Moreover, Nell-1 overexpression in osteoblasts was sufficient to promote alkaline phosphatase expression and micronodule formation. Conversely, downregulation of Nell-1 inhibited osteoblast differentiation in vitro. In summary, Nell-1 overexpression induced calvarial overgrowth resulting in premature suture closure in a rodent model. Nell-1, therefore, has a novel role in CS development, perhaps as part of a complex chain of events resulting in premature suture closure. On a cellular level, Nell-1 expression may modulate and be both sufficient and required for osteoblast differentiation.
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Affiliation(s)
- Xinli Zhang
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California 90095, USA
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