Gene Expression and Accumulation of Fibrillin-1, Fibrillin-2, and Tropoelastin in Cultured Periodontal Fibroblasts

The elastic system fibers consist of three types--oxytalan, elaunin, and elastic fibers--differing in their relative microfibril and elastin contents. All three types are found in human gingiva, but human periodontal ligaments contain only elastin-free fibers. We examined cultured human gingival fibroblasts (HGF) and cultured human periodontal ligament fibroblasts (HPLF) to determine the gene expression of fibrillin-1 and fibrillin-2 (the major components of microfibrils) and of tropoelastin. In addition, we assessed the degree of accumulation of these proteins in the extracellular matrix. Northern blot analysis revealed that the level of expression of fibrillin-1 and fibrillin-2 was higher in HGF than in HPLF. However, examination of matrix samples from HGF and HPLF cell layers showed that there was no difference in fibrillin-1 accumulation, although fibrillin-2 accumulated to a much greater extent in the HGF-derived matrix. Tropoelastin was expressed only in and around HGF. These results show a correlation between gene expression and the accumulation of tropoelastin and fibrillin-2 in HGF.