Biomedical subjects
Publications and source records attributed to Jun-Hyeog Jang.
New bone formation on an RGD-containing oligopeptide-coated surface in vitro and in vivo was investigated. The surface showed two-fold higher osteoblastic cell adhesion and differentiation in vitro, and revealed statistically significant in vivo bone formation compared with the control (P < 0.05).
OBJECTIVES: Outstanding mechanical properties, resistance to scratching and high biocompatibility make zirconia/alumina ceramics interesting for dental applications. To solve the problem of the well-known low temperature degradation and to provide stable mechanical properties a novel zirconia alloy ((Y,Nb)-TZP/alumina) was developed. The aim of this study was to investigate the initial bone cell response to this new zirconia/alumina composite ceramic. METHODS: HOS cells were cultured on zirconia/alumina composite (Zc) and pure titanium (Ti) discs. Surface topography was examined by atomic force microscopy (AFM), cell morphology by scanning electron microscopy (SEM). Cell proliferation (MTS) and alkaline phosphatase activity was measured at 1, 4 and 8 days. The mRNA expression of Cycline D1, the cell cycle regulating gene, integrin beta 1, osteonectin (ON) and beta-actin were evaluated by RT-PCR analysis after 12, 24 and 48 h. RESULTS: Both substrates showed a very smooth character with R(a)-values in the range of 0.002-0.113 microm supporting a continuous cellular growth. After 8 days, cell proliferation on Zc was higher than on Ti. The mRNA expression of cyclin D1 showed similar activity after 48 h on both surfaces, ALP activity was higher on Zc after 8 days. ON expression however showed no difference between the two groups. SIGNIFICANCE: Our data demonstrate that this new zirconia composite ceramic showed at least equivalent or slightly better biological response of osteoblast-like HOS cells than pure titanium during a short-time cell culture period.
We have previously shown that the recombinant human fibronectin (FN) fragment composed of central cell binding domains (CCBD) spanning the ninth and tenth type III domains promotes cell adhesion and proliferation of osteoblasts. In the present study, we investigated the biological potency of heparin-binding domain (HBD) of FN spanning the twelfth and fourteenth type III domains. The HBD of FN significantly enhances the RGD-containing CCBD-mediated cell adhesion and proliferation in HOS cells (P < 0.05).
We have previously demonstrated that the expression of FGFR3 is frequently downregulated in colorectal carcinoma cells. Here we have shown that FGFR1 is overexpressed in colorectal carcinoma cells and the gene expressions between FGFR1 and FGFR3 are mutually exclusive. Moreover, we have also shown that the disruption of FGFR1 expression by introducing of FGFR1 siRNA was effective in elevating FGFR3 expression and tumor suppressive activities. Thus, FGFR1 may confer a selectable advantage on clones of cells in colorectal tumorigenesis, favoring proliferation, whereas FGFR3 may have the effect of an unfavorable negative regulation of progression of the carcinomas to malignancy, promoting differentiation. Our results indicate that the reciprocal relationship in gene expression between FGFR1 and FGFR3 in colorectal tissue plays an important role in the progression of the carcinomas to malignancy.
Tenascin-C (TnC) is an extracellular matrix protein that is highly expressed in tumor stroma. In this report, we examined the roles of TnC-mediated cell adhesion in the modulation of chondrosarcoma cell survival. We found that hTnC-mediated adhesion could confer a significant (P<0.05) survival advantage to human chondrosarcoma cell line, JJ012, following serum-deprivation compared with the same cells grown on poly-lysine. This pro-survival signal was due to the activation of the Akt upon adhesion to hTnC. Moreover, hTnC-induced Akt activation was blocked by LY294002 and the expression of dominant-negative Akt. Taken together, these studies support that the TnC-mediated adhesion can promote cell survival through Akt in human chondrosarcoma cells.
Osteopontin is a major non-collagenous bone matrix protein secreted into the mineralizing extracellular matrix by osteoblasts during bone development. Recombinant human osteopontin (hOPN) that includes the Arg-Gly-Asp (RGD) cell recognition site was expressed in Escherichia coli and the purified osteopontin increased cell adhesion, proliferation and differentiation of osteoblast cells (p<0.05).
Keratinocyte growth factor-2 (KGF-2) is found in dermal papilla fibroblasts and its receptor, fibroblast growth factor receptor 2 (FGFR2), in the neighboring outer root sheath of keratinocytes. Administration of recombinant human KGF-2 (rhKGF-2) at 10 ng ml(-1) significantly stimulated human hair-follicle cell proliferation in organ culture (26-35%). Thus, rhKGF-2 is a promising therapeutic agent to stimulate human hair growth.
Cell adhesion to extracellular matrices, including fibronectin, results in clustering of integrins in focal adhesions. To promote the clustering of fibronectin and thus enhance its activity at the sites of focal adhesion formation, we have engineered a fusion protein containing recombinant fibronectin fragment (hFN) connected to the tetramerization helix domain of lac repressor for oligomeric assembly. Purified Lac-hFN fusion protein exhibited significant increase of cell adhesion and proliferation of GF cells compared with hFN alone (p < 0.05).
The surface of titanium implants is in direct contact with host tissue and plays a critical role in determining biocompatibility. Fibronectin (FN) and vitronectin (VN) are major cell adhesive proteins found in the extracellular matrix (ECM) of various tissues, and in circulating blood. The aim of this study was to evaluate the engineered biomimetic surface of titanium by using recombinant fragment of FN(8-10) and VN(NTD) that contains the binding site for integrins. MC3T3-E1 cells seeded upon the FN(8-10)-coated titanium showed a marked increase in cell adhesion, proliferation, and differentiation over VN(NTD)-coated titanium. In addition, we confirmed that the surface properties of titanium prefer for FN(8-10) over VN(NTD) (p<0.05) in protein adhesion. These results suggest that the FN(8-10)-modified titanium surface can be used to improve the osseointegration of titanium implants by enhancing bone formation.
We have previously shown that fibroblast growth factor receptor 2 (FGFR2) plays an important role in gastric carcinogenesis. In this study, we have used a differential display approach to identify basic fibroblast growth factor (bFGF)-inducible genes in gastric cancer cells. Here, we report that one of these genes is predicted to encode a RING finger protein, designated FIGC. The FIGC gene was found to encode a polypeptide of 381 amino acids with a novel RING finger module at the NH2-terminus and the COOH-terminal proline-rich region. Using an in vitro ubiquitination assay with recombinant protein, we demonstrate that FIGC has intrinsic E3 ubiquitin ligase activity and promotes ubiquitination. Our data indicate that FIGC upregulation in response to bFGF in gastric cancer might be implicated in carcinogenesis through dysregulation of growth modulator.
The interaction between tenascin-C (TN-C), a multi-subunit extracellular matrix protein, and heparin was examined using a surface plasmon resonance-based technique on a Biacore system. The aims of the present study were to examine the affinity of fibronectin type III repeats of TN-C fragments (TNIII) for heparin, to investigate the role of the TNIII4 domains in the binding of TN-C to heparin, and to delineate a sequence of amino acids within the TNIII4 domain, which mediates cooperative heparin binding. At a physiological salt concentration, and pH 7.4, TNIII3-5 binds to heparin with high affinity (K(D) = 30 nm). However, a major heparin-binding site in TNIII5 produces a modest affinity binding at a K(D) near 4 microm, and a second site in TNIII4 enhances the binding by several orders of magnitude, although it was far too weak to produce an observable binding of TNIII4 by itself. Moreover, mutagenesis of the KEDK sequence in the TNIII4 domain resulted in the significant reduction of heparin-binding affinity. In addition, residues in the KEDK sequences are conserved in TN-C throughout mammalian evolution. Thus the structure-based sequence alignment, mutagenesis, and sequence conservation data together reveal a KEDK sequence in TNIII4 suggestive of a minor heparin-binding site. Finally, we demonstrate that TNIII4 contains binding sites for heparin sulfate proteoglycan and enhances the heparin sulfate proteoglycan-dependent human gingival fibroblast adhesion to TNIII5, thus providing the biological significance of heparin-binding site of TNIII4. These results suggest that the heparin-binding sites may traverse TNIII4-5 and thus require KEDK in TNIII4 for optimal heparin-binding.
There is a synergistic effect between fibronectin and fibroblast growth factor 2 (FGF-2) on osteoblast cell adhesion through an extracellular, signal-regulated kinase pathway. Here we describe the engineering of a fusion protein containing fibronectin fragment (FNIII9-10) connected to the COOH-terminus of FGF-2. Purified FGF2-FNIII9-10 fusion protein exhibited a significant increase of cell adhesion and proliferation of MG63 cells compared with FNIII9-10 alone (p < 0.05).
Recombinant human tenascin peptide (hTNCIII3) that includes the Arg-Gly-Asp (RGD) cell recognition site was expressed in Escherichia coli using a prokaryotic expression system. Addition of recombinant hTNCIII3 peptide enhanced cell adhesion and survival of human chondrocytes by about 3-fold in each case.
An anodized surface significantly enhanced the adhesion of human osteoblast-like MG-63 cells to titanium. Using cDNA microarray analysis, five genes were differentially expressed while the rest remained unaltered. The results demonstrated that the anodized surface enhances cellular adhesion without significantly affecting the pattern of gene expression.
BACKGROUND: Periodontal ligament (PDL) cells, connecting root cementum with alveolar bone, are important for periodontal wound healing. In order to obtain a predictable periodontal regeneration, selective adhesion and proliferation of PDL cells are essential. The purpose of this study was to investigate the effects of synthetic peptides mimicking cell-binding domain of fibronectin (FN) on human PDL cells. METHODS: Two types of oligopeptides, Gly3-Pro-His-Ser-Arg-Asn-Gly6-Arg-Gly-Asp-Gly (G3PHSRNG6RGDG) and Gly3-His-Pro-Asn-Arg-Ser-Gly6-Arg-Gly-Asp-Gly (G3HPNRSG6RGDG), were constructed using a solid-phase peptide synthesizer. Fibronectin type III ninth to tenth domain (FN III 9-10) and Arg-Gly-Asp-Ser (RGDS) were prepared for comparison with the effects of synthetic peptides. These peptides were coated onto 96-well cell culture plates with 0.001 approximately 100 microM concentrations. Cultured human PDL cells were then applied to the peptide-coated wells at a density of 1 x 10(4)/well. After 1 hour incubation at 37 degrees C, adhered cells were fixed, stained, and examined by phase contrast microscopy for cell spreading assay. Attached PDL cells were solubilized with 2% sodium dodecyl sulfate (SDS) for the cell attachment assay by measuring absorbance at 595 nm in microplate reader. Western blot analysis was performed to determine extracellular signal-regulated kinase (ERK1/2) activity. RESULTS: Cell attachment and spreading assays revealed that G3PHSRNG6RGDG (> or = 10 microM) possesses similar adhesive behavior to FN III 9-10. G3PHSRNG6RGDG showed a comparable ERK1/2 activity when compared to FN III 9-10. CONCLUSIONS: G3PHSRNG6RGDG enhanced an attachment and spreading of human PDL cells thereby increasing ERK1/2 activity. Taken together, it is anticipated that this peptide might be a potential tool for arranging a biologically attractive environment for PDL cells, which would enhance periodontal regeneration efficacy.
We have previously reported the alternatively spliced transcripts of fibroblast growth factor receptor (FGFR) 3 derived by aberrant splicing in human cancers. Here, we describe a novel splice variant of FGFR2 (FGFR2DeltaIII) arising from skipping exons 7-10, resulting in the deletion of Ig-like-III domain in human chondrosarcoma cell. Sf9 cells expressing FGFR2DeltaIII were able to bind FGF1, FGF2, and FGF7, leading to loss of ligand-binding specificity. Together with our previous findings, the present studies suggest that mRNA splicing plays an important role in the regulation of FGFRs' function.
A recombinant peptide fragment of vitronectin (rVN143), that includes the Arg-Gly-Asp (RGD) cell recognition site, was expressed in Escherichia coli using a prokaryotic expression system. The addition of recombinant rVN143 peptide enhances cell adhesion and proliferation similar (approximately 70%) to those of native VN.
A fibronectin fragment, which spans from the ninth to tenth type III domain, showed > 95% biological activity in promoting osteoblast adhesion, proliferation and differentiation level compared with those of native fibronectin (FN) molecule. This suggests that the FN type III ninth-tenth domain fragment serves a good substitute for native FN in biomimetic application for osteogenesis.