Refined Genomic Localization of the Genetic Lesion in the Osteopetrosis (op) Rat and Exclusion of Three Positional and Functional Candidate Genes, Clcn7, Atp6v0c, and Slc9a3r2
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Osteopetrosis is a disease characterised by a generalized skeletal sclerosis resulting from a reduced osteoclast-mediated bone resorption. Several spontaneous mutations lead to osteopetrotic phenotypes in animals. Moutier et al. (1974) discovered the osteopetrosis (op) rat as a spontaneous, lethal, autosomal recessive mutant. op rats have large nonfunctioning osteoclasts and severe osteopetrosis. Dobbins et al. (2002) localized the disease-causing gene to a 1.5-cM genetic interval on rat chromosome 10, which we confirm in the present report. We also refined the genomic localization of the disease gene and provide statistical evidence for a disease-causing gene in a small region of rat chromosome 10. Three strong functional candidate genes are within the delineated region. Clcn7 was previously shown to underlie different forms of osteopetrosis, in both human and mice. ATP6v0c encodes a subunit of the vacuolar H(+)-ATPase or proton pump. Mutations in TCIRG1, another subunit of the proton pump, are known to cause a severe form of osteopetrosis. Given the critical role of proton pumping in bone resorption, the Slc9a3r2 gene, a sodium/hydrogen exchanger, was also considered as a candidate for the op mutation. RT-PCR showed that all 3 genes are expressed in osteoclasts, but sequencing found no mutations either in the coding regions or in intron splice junctions. Our ongoing mutation analysis of other genes in the candidate region will lead to the discovery of a novel osteopetrosis gene and further insights into osteoclast functioning.
KeywordsOsteopetrosis Osteosclerosis Rat Clcn7 Atp6v0c Slc9a3r2
This work was supported by Grant DE07444 to P.R.O. B.P. holds a Ph.D. studentship from the European Calcified Tissue Society. This work was supported by F.W.O. Vlaanderen Grant G.0117.06 and by a grant from the Special Research Fund (B.O.F.) of the University of Antwerp, both to W.V.H.
- 6.Frattini A, Orchard PJ, Sobacchi C, Giliani S, Abinun M, Mattsson JP, Keeling DJ, Andersson AK, Wallbrandt P, Zecca L, Notarangelo LD, Vezzoni P, Villa A (2000) Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis. Nat Genet 25:343–346PubMedCrossRefGoogle Scholar
- 7.Van Wesenbeeck L, Odgren PR, Coxon FP, Frattini A, Moens P, Perdu B, Mackay CA, Van Hul E, Timmermans JP, Vanhoenacker F, Jacobs R, Peruzzi B, Teti A, Helfrich MH, Rogers MJ, Villa A, Van Hul W (2007) Involvement of PLEKHM1 in osteoclastic vesicular transport and osteopetrosis in incisors absent rats and humans. J Clin Invest 117:919–930PubMedCrossRefGoogle Scholar
- 8.Sobacchi C, Frattini A, Guerrini MM, Abinun M, Pangrazio A, Susani L, Bredius R, Mancini G, Cant A, Bishop N, Grabowski P, Del Fattore A, Messina C, Errigo G, Coxon FP, Scott DI, Teti A, Rogers MJ, Vezzoni P, Villa A, Helfrich MH (2007) Osteoclast-poor human osteopetrosis due to mutations in the gene encoding RANKL. Nat Genet 39:960–962PubMedCrossRefGoogle Scholar
- 9.Guerrini MM, Sobacchi C, Cassani B, Abinun M, Kilic SS, Pangrazio A, Moratto D, Mazzolari E, Clayton-Smith J, Orchard P, Coxon FP, Helfrich MH, Crockett JC, Mellis D, Vellodi A, Tezcan I, Notarangelo LD, Rogers MJ, Vezzoni P, Villa A, Frattini A (2008) Human osteoclast-poor osteopetrosis with hypogammaglobulinemia due to TNFRSF11A (RANK) mutations. Am J Hum Genet 83:64–76PubMedCrossRefGoogle Scholar
- 10.Driessen GJ, Gerritsen EJ, Fischer A, Fasth A, Hop WC, Veys P, Porta F, Cant A, Steward CG, Vossen JM, Uckan D, Friedrich W (2003) Long-term outcome of haematopoietic stem cell transplantation in autosomal recessive osteopetrosis: an EBMT report. Bone Marrow Transplant 32:657–663PubMedCrossRefGoogle Scholar
- 12.Van Wesenbeeck L, Odgren PR, MacKay CA, D’Angelo M, Safadi FF, Popoff SN, Van Hul W, Marks SC Jr (2002) The osteopetrotic mutation toothless (tl) is a loss-of-function frameshift mutation in the rat Csf1 gene: evidence of a crucial role for CSF-1 in osteoclastogenesis and endochondral ossification. Proc Natl Acad Sci USA 99:14303–14308PubMedCrossRefGoogle Scholar
- 19.Milhaud G, Labat ML, Graf B, Juster M, Balmain N, Moutier R, Toyama K (1975) Kinetic, radiographic, and histologic demonstration of the curing of congenital osteopetrosis in rats. CR Acad Sci Hebd Seances Acad Sci D 280:2485–2488Google Scholar
- 22.Dobbins DE, Joe B, Hashiramoto A, Salstrom JL, Dracheva S, Ge L, Wilder RL, Remmers EF (2002) Localization of the mutation responsible for osteopetrosis in the op rat to a 1.5-cM genetic interval on rat chromosome 10: identification of positional candidate genes by radiation hybrid mapping. J Bone Miner Res 17:1761–1767PubMedCrossRefGoogle Scholar
- 24.Pangrazio A, Poliani PL, Megarbane A, Lefranc G, Lanino E, Di Rocco M, Rucci F, Lucchini F, Ravanini M, Facchetti F, Abinun M, Vezzoni P, Villa A, Frattini A (2006) Mutations in OSTM1 (grey lethal) define a particularly severe form of autosomal recessive osteopetrosis with neural involvement. J Bone Miner Res 21:1098–1105PubMedCrossRefGoogle Scholar
- 26.Del Fattore A, Peruzzi B, Rucci N, Recchia I, Cappariello A, Longo M, Fortunati D, Ballanti P, Iacobini M, Luciani M, Devito R, Pinto R, Caniglia M, Lanino E, Messina C, Cesaro S, Letizia C, Bianchini G, Fryssira H, Grabowski P, Shaw N, Bishop N, Hughes D, Kapur R, Datta H, Taranta A, Fornari R, Migliaccio S, Teti A (2005) Clinical, genetic and cellular analysis of forty-nine osteopetrotic patients: implications for diagnosis and treatment. J Med Genet (online). Available at: http://jmg.bmj.com/cgi/content/abstract/jmg.2005.036673v1