The avian corneal primary stroma has a unique structure. It consists of orthogonally arranged layers of collagen fibrils, composed of type I and II collagens that are produced by corneal epithelial cells. The primary stroma contains also type IX collagen, at least as a transitory component, and my recent studies show that the corneal form of this unique extracellular matrix molecule is different from that which is expressed in cartilage. Whereas cartilage type IX molecules contain a large globular amino-terminal domain located in the perifibrillar matrix along collagen fibrils, this domain is absent in corneal type IX collagen molecules. I propose that analysis of this difference will provide novel and exciting clues to answer the general question of what mechanisms cells utilize to build unique extracellular matrices in different tissues from a common set of extracellular matrix genes. As a first step in this analysis, DNA cloning and sequencing techniques will be applied to characterize the structure of corneal type IX collagen. In addition, rotary shadowing electron microscopy, western blotting and immunoprecipitation will be used to characterize the corneal type IX collagen protein. Second, the differential expression of the two different type IX collagens, the corneal and cartilage forms, will be examined by means of RNase protection methods in different tissues such as cornea, sclera, lens, retina, notochord, neural tube epithelium and cartilage. Third, to precisely locate the cells expressing the two forms of type IX collagen, in situ hybridization studies will be performed using DNA probes containing cornea and cartilage specific type IX collagen nucleotide sequences. Finally, the al(IX) gene will be examined in experiments aimed at deciphering the molecular mechanisms involved in expression of the corneal form of type IX collagen.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29EY008219-04
Application #
3465760
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1989-08-01
Project End
1994-07-31
Budget Start
1992-08-01
Budget End
1993-07-31
Support Year
4
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Harvard University
Department
Type
Schools of Dentistry
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Ting, K; Ramachandran, H; Chung, K S et al. (1999) A short isoform of Col9a1 supports alveolar bone repair. Am J Pathol 155:1993-9
Jahangiri, L; Devlin, H; Ting, K et al. (1998) Current perspectives in residual ridge remodeling and its clinical implications: a review. J Prosthet Dent 80:224-37
Chung, K S; Park, H H; Ting, K et al. (1995) Modulated expression of type X collagen in Meckel's cartilage with different developmental fates. Dev Biol 170:387-96
Karimbux, N Y; Nishimura, I (1995) Temporal and spatial expressions of type XII collagen in the remodeling periodontal ligament during experimental tooth movement. J Dent Res 74:313-8
Ting, K; Petropulos, L A; Iwatsuki, M et al. (1993) Altered cartilage phenotype expressed during intramembranous bone formation. J Bone Miner Res 8:1377-87
Asahina, I; Sampath, T K; Nishimura, I et al. (1993) Human osteogenic protein-1 induces both chondroblastic and osteoblastic differentiation of osteoprogenitor cells derived from newborn rat calvaria. J Cell Biol 123:921-33
Karimbux, N Y; Rosenblum, N D; Nishimura, I (1992) Site-specific expression of collagen I and XII mRNAs in the rat periodontal ligament at two developmental stages. J Dent Res 71:1355-62
Muragaki, Y; Nishimura, I; Henney, A et al. (1990) The alpha 1 (IX) collagen gene gives rise to two different transcripts in both mouse embryonic and human fetal RNA. Proc Natl Acad Sci U S A 87:2400-4