Osteogenesis imperfecta (OI) is a clinically, genetically and biochemically heterogeneous disorder characterized by bone fragility and other connective tissue abnormalities. In the vast majority of affected individuals the clinical condition results from mutations in the two genes (COL1A1 and COL1A2) that encode the chains of type I procoliagen. The objectives of the studies proposed in this application are to characterize the mutations in the collagen genes that give rise to different forms of OI, to determine the relationship among the nature of the mutation, the gene in which it is located, and the clinical phenotype, to determine how mutations alter the intracellular and extracellular behavior of molecules that contain abnormal chains, to identify the parent of origin of new dominant mutations, and to determine the extent of mosaicism for mutations in collagen genes among parents of first affected individuals. For mutations that alter chain structure, the site of the mutation will be approximated by peptide mapping, the precise location of the mutation will be determined by single-base mismatch chemical cleavage or single stranded conformational polymorphisms, the appropriate region of cDNA from fibroblasts or genomic DNA will be amplified and either sequenced directly or cloned into M13 and selected clones will be sequenced. For mutations that alter the expression of collagen genes, the abnormal allele will be identified by the absence of expressed polymorphic markers from the mRNA synthesized from that gene (in heterozygotes) and the structure of the mutation identified and characterized following search of the gene using base mismatch chemical cleavage of single stranded conformational polymorphisms to detect regions of difference. The effects of abnormal chains in type I procollagen molecules will be determined by examinining the kinetics of secretion and the effects of RER binding proteins on secretion, the efficiency of secretion of molecules with one or more than one abnormal chain, the effect-,of these molecules on molecular structure at the EM level, the thermal stability of molecules, and the ability of molecules to participate in fibrillogenesis. Finally, the extent of mosaicism will be determined by examination of tissues from parents and measuring the presence of the mutant allele by digestions with appropriate restriction enzymes or by allele-specific oligonucleotide hybridization. These studies should help to understand the molecular basis of OI, and how mutations are translated to phenotype. Finally, they have implications for the pathogenesis of more common disorders of bone formation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR041223-04
Application #
2080564
Study Section
General Medicine B Study Section (GMB)
Project Start
1992-01-05
Project End
1996-07-31
Budget Start
1995-01-01
Budget End
1996-07-31
Support Year
4
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Washington
Department
Pathology
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Pace, James M; Wiese, Mary; Drenguis, Andrea S et al. (2008) Defective C-propeptides of the proalpha2(I) chain of type I procollagen impede molecular assembly and result in osteogenesis imperfecta. J Biol Chem 283:16061-7
Morello, Roy; Bertin, Terry K; Chen, Yuqing et al. (2006) CRTAP is required for prolyl 3- hydroxylation and mutations cause recessive osteogenesis imperfecta. Cell 127:291-304
Persikov, Anton V; Pillitteri, Rian J; Amin, Priyal et al. (2004) Stability related bias in residues replacing glycines within the collagen triple helix (Gly-Xaa-Yaa) in inherited connective tissue disorders. Hum Mutat 24:330-7
Schwarze, Ulrike; Hata, Ryu-Ichiro; McKusick, Victor A et al. (2004) Rare autosomal recessive cardiac valvular form of Ehlers-Danlos syndrome results from mutations in the COL1A2 gene that activate the nonsense-mediated RNA decay pathway. Am J Hum Genet 74:917-30
Pace, James M; Corrado, Marcella; Missero, Caterina et al. (2003) Identification, characterization and expression analysis of a new fibrillar collagen gene, COL27A1. Matrix Biol 22:3-14
Johnson, M T; Morrison, S; Heeger, S et al. (2002) A variant of osteogenesis imperfecta type IV with resolving kyphomelia is caused by a novel COL1A2 mutation. J Med Genet 39:128-32
Marlowe, A; Pepin, M G; Byers, P H (2002) Testing for osteogenesis imperfecta in cases of suspected non-accidental injury. J Med Genet 39:382-6
Pace, J M; Kuslich, C D; Willing, M C et al. (2001) Disruption of one intra-chain disulphide bond in the carboxyl-terminal propeptide of the proalpha1(I) chain of type I procollagen permits slow assembly and secretion of overmodified, but stable procollagen trimers and results in mild osteogenesis imperfec J Med Genet 38:443-9
Byers, P H (2001) Folding defects in fibrillar collagens. Philos Trans R Soc Lond B Biol Sci 356:151-7; discussion 157-8
Bateman, J F; Freddi, S; Lamande, S R et al. (1999) Reliable and sensitive detection of premature termination mutations using a protein truncation test designed to overcome problems of nonsense-mediated mRNA instability. Hum Mutat 13:311-7

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