Regeneration of the periodontium is one of the ultimate goals of periodontal therapy. To achieve successful regeneration, we must have a thorough understanding of the cellular and molecular biologic events in the given tissue. The extracellular matrix glycoproteins - tenascin (Tn) and fibronectin (Fn) are prominently expressed during embryonic development and wound healing. The proposed studies are aimed at analyzing the biologic functions of specific domains of Tn and Fn using in vitro and in vivo assays. In the first specific aim of the continuing proposal, we will continue studies on the mapping of functional domains of Tn. All the members of the Tn family (Tn-C and its two paralogues Tn-R and Tn-X) have the last three Fn-III repeats and the C-terminal fibrinogen-like domain well conserved. Since this region in Tn-C has cell- and heparin-binding activity, we will further characterize the biologic activity in this region. We will test the hypothesis that the C-terminal ends of TnC, TnR and TnX have significant biological activities. These would include mediating cell-cell adhesion (important in events such as angiogenesis and epithelial cell migration in healing wounds), downregulating cell proliferation, and probably affecting programmed cell death. In the second specific aim, the biologic functions of the alternatively- spliced domains EIIIB and ElIIA of human Fn will be characterized in detail. Preliminary data shows that the presence of these domains enhances cell adhesion at low concentrations. We will test the hypothesis that domains EIIIB and for EIIIA of human Fn serve important functions during development and wound healing by either conformational modifications or having their own novel sites with biologic activities. The structural and biologic effects of including these domains in recombinant human Fn fragments will be studied. In the third specific aim, we will examine periodontal wound healing/tissue regeneration and bone matrix-induced endochondral bone formation in TnC-/- (TnC knockout mice) mice. Since TnC is prominently expressed during cartilage/bone formation and in the adult periodontal ligament, we expect to see differences in the healing events in TnC-1- mice compared to the TNC +/- and TNC +/+ mice. The date from these studies should shed some important light on the biologic functions of Tn and Fn. Information gained from these studies will be used to develop strategies for biochemically-mediated healing and regeneration of periodontal tissues where recombinant polypeptides of these proteins can be used to enhance specific cellular events.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE007801-09
Application #
2668237
Study Section
Special Emphasis Panel (ZRG4-OBM-2 (02))
Project Start
1988-07-01
Project End
2000-02-29
Budget Start
1998-03-01
Budget End
1999-02-28
Support Year
9
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Dentistry
Type
Schools of Dentistry
DUNS #
078861598
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Sahlberg, C; Aukhil, I; Thesleff, I (2001) Tenascin-C in developing mouse teeth: expression of splice variants and stimulation by TGFbeta and FGF. Eur J Oral Sci 109:114-24
Aukhil, I (2000) Biology of wound healing. Periodontol 2000 22:44-50
Hashimoto-Uoshima, M; Yan, Y Z; Schneider, G et al. (1997) The alternatively spliced domains EIIIB and EIIIA of human fibronectin affect cell adhesion and spreading. J Cell Sci 110 ( Pt 18):2271-80
Leahy, D J; Aukhil, I; Erickson, H P (1996) 2.0 A crystal structure of a four-domain segment of human fibronectin encompassing the RGD loop and synergy region. Cell 84:155-64
Aukhil, I; Sahlberg, C; Thesleff, I (1996) Basal layer of epithelium expresses tenascin mRNA during healing of incisional skin wounds. J Periodontal Res 31:105-12
Leahy, D J; Erickson, H P; Aukhil, I et al. (1994) Crystallization of a fragment of human fibronectin: introduction of methionine by site-directed mutagenesis to allow phasing via selenomethionine. Proteins 19:48-54
Aukhil, I; Joshi, P; Yan, Y et al. (1993) Cell- and heparin-binding domains of the hexabrachion arm identified by tenascin expression proteins. J Biol Chem 268:2542-53
Joshi, P; Chung, C Y; Aukhil, I et al. (1993) Endothelial cells adhere to the RGD domain and the fibrinogen-like terminal knob of tenascin. J Cell Sci 106 ( Pt 1):389-400
Leahy, D J; Hendrickson, W A; Aukhil, I et al. (1992) Structure of a fibronectin type III domain from tenascin phased by MAD analysis of the selenomethionyl protein. Science 258:987-91
Aukhil, I (1991) Biology of tooth-cell adhesion. Dent Clin North Am 35:459-67

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