• Journal of Plant Biology
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• 제36권4호
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• pp.391-398
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• 1993

식물에서도 동물에서와 같이 RGD(Arg-Gly-Asp) sequence를 매개로 원형질막과 extracellular matrix(ECM)가 연결되어 있다는 사실이 알려지고 있으므로 RGD sequence가 식물세포의 생장, 분화 등의 여러 가지 생리적인 현상에 관여하리라는 가능성을 생각할 수 있다. 그래서 RGD sequence가 당근(Daucus carota L.) 배양세포에서 에틸렌 생성에 미치는 영향을 조사하였다. RGD sequence를 포함하는 합성 peptide는 당근 배양세포에서 에틸렌의 생성을 촉진시켰다. RGD peptide는 Indole-3-acetic acid(IAA)와 함께 처리한 경우 에틸렌 생성을 더욱 촉진시켰으며, ACC synthase의 활성도 증가시켰다. RGD sequence가 에틸렌 생성을 촉진시킬 때 어떠한 특이성이 있는가를 확인하기 위해 이와 유사한 RGE(Arg-Gly-Glu) peptide, RGK(Arg-Gly-Lys) peptide를 각각 처리하여 보았다. RGE peptide는 RGD peptide와 마찬가지로 에틸렌 생성을 촉진시켰으나 RGK peptide는 에틸렌 생성에 영향을 미치지 않았다. 따라서 RGD peptide의 에틸렌 생성 촉진작용은 RGD dequence를 포함하는 RGD peptide가 ACC synthase의 활성을 증가시켜서 일어나는 현상이라 생각되며, 또한 특정한 아미노산 서열을 요구하는 특이적 반응이라고 생각된다.

• Molecules and Cells
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• 제19권2호
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• pp.205-211
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• 2005

The Arg-Gly-Asp (RGD) sequence serves as the primary recognition site in extracellular matrix proteins, and peptides containing this sequence can mimic the biological activities of matrix proteins. We have initiated structure-function studies of two RGD containing peptides, RGD-5(AGGDD) and cyclic RGD-6(CARGDDC). Assays have shown that cyclic RGD-peptides inhibit platelet aggregation more efficiently than linear ones. NMR data revealed that RGD-5 and RGD-6 have entirely different conformation. RGD-5 has a linear extended structure and RGD-6 has a stable loop conformation. In RGD-5 the guanidinium group of Arg2 and the carboxyl group of Asp4 lie in parallel, whereas the side-chains of Arg3 and Asp5 of RGD-6 are located in different planes, supporting the idea that the stability of the cyclic form derives from the packing of the side chain of the Arg and Asp residues. The structural features of these peptides could provide a basis for designing new drugs against diseases related to platelet aggregation and as cancer antagonists.

• Macromolecular Research
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• 제16권6호
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• pp.517-523
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• 2008

A RGD (Arg-Gly-Asp) conjugated chitosan hydrogel was used as a cell-supporting scaffold for articular cartilage regeneration. Thermosensitive chitosan-Pluronic (CP) has potential biomedical applications on account of its biocompatibility and injectability. A RGD-conjugated CP (RGD-CP) copolymer was prepared by coupling the carboxyl group in the peptide with the residual amine group in the CP copolymer. The chemical structure of RGD-CP was characterized by $^1H$ NMR and FT IR. The concentration of conjugated RGD was quantified by amino acid analysis (AAA) and rheology of the RGD-CP hydrogel was investigated. The amount of bound RGD was $0.135{\mu}g$ per 1 mg of CP copolymer. The viscoelastic parameters of RGD-CP hydrogel showed thermo-sensitivity and suitable mechanical strength at body temperature for cell scaffolds (a> 100 kPa storage modulus). The viability of the bovine chondrocyte and the amount of synthesized glycosaminoglycans (GAGs) on the RGD-CP hydrogels were evaluated together with the alginate hydrogels as a control over a 14 day period. Both results showed that the RGD-CP hydrogel was superior to the alginate hydrogel. These results show that conjugating RGD to CP hydro gels improves cell viability and proliferation, including extra cellular matrix (ECM) expression. Therefore, RGD conjugated CP hydrogels are quite suitable for a chondrocyte culture and have potential applications to the tissue engineering of articular cartilage tissue.

• 공업화학
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• 제31권1호
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• pp.67-72
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• 2020

Biomaterials are frequently functionalized with Arg-Gly-Asp (RGD) peptides to provide cell adhesion sites. In this study, RGD peptides were enzymatically coupled on to the surface of fibroin microspheres. Papain exhibited a strong preference for dansyl phenylalanine for the peptide formation with fibroin microspheres. Thus, RGD1 peptide was designed to carry cysteine to both sides of the sequence, glycine as a spacer and two residues of phenylalanine at the C-terminal (CRGDCGFF). The enzymatic modification facilitated by an increasing amount of substrate and by the presence of organic solvent, dimethylsulfoxide at 25% (v/v). Microspheres coupled with RGD1, showed a significantly different precipitation property and an increased apparent volume, possibly due to the steric hindrance of RGD peptides on the surface. Transmission electron microscopy also confirmed the presence of cysteine residues in RGD1 coupled on the surface of microspheres stained with gold nanoparticles. RGD1-microspheres significantly facilitated the growth of murine fibroblast 3T3 cells even under non-adhesion culture conditions.

• Journal of Microbiology and Biotechnology
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• 제24권7호
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• pp.905-913
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• 2014

Lj-RGD3, an RGD (Arg-Gly-Asp) toxin protein from the salivary gland of Lampetra japonica, exhibits antifungal activity against Candida albicans. Lj-RGD3 has three RGD motifs and shows homology to histidine-rich glycoprotein. We synthesised two mutant derivatives of Lj-RGD3: Lj-26, which lacks all three RGD motifs and contains no His residues; and Lj-112, which lacks only the three RGD motifs. We investigated the effects of the wild-type and mutated toxins on a gram-positive bacterium (Escherichia coli), a gram-negative bacterium (Staphylococcus aureus), and a fungus (C. albicans). rLj-RGD3 and its mutants exhibited antifungal but not antibacterial activity, as measured by a radial diffusion assay. The C. albicans inhibition zone induced by rLj-112 was larger than that induced by the other proteins, and its inhibitory effect on C. albicans was dose-dependent. In viable-count assays, the rLj-112 MIC was $7.7{\mu}M$, whereas the MIC of the positive control (ketoconazole) was $15{\mu}M$. Time-kill kinetics demonstrated that rLj-112 effectively killed C. albicans at $1{\times}$ and $2{\times}$ MIC within 12 and 6 h, respectively. Electron microscopy analysis showed that rLj-RGD3 and rLj-112 induced C. albicans lysis. Our results demonstrate a novel anticandidal activity for rLj-RGD3 and its mutant derivatives.

• 대한방사성의약품학회지
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• 제6권2호
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• pp.92-101
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• 2020

The cyclic Arg-Gly-Asp (cRGD) peptide is well-known as a binding molecule to the integrin α_vβ₃ receptor which is highly expressed on activated endothelial cells and new blood vessels in tumors. Although numerous results have been reported by the usage of cRGD peptide-based ligands for cancer diagnosis and therapy, the distinct mechanisms, and functions of cRGD-integrin binding to cancer cells are still being investigated. In this study, we evaluated the internalization efficacy of different types of cRGD peptides (monomer, dimer and tetramer form) in integrin α_vβ₃ overexpressing cancer cells. Western blot and flow cytometric analysis showed U87MG expresses highly integrin α_vβ₃, whereas CT-26 does not show integrin α_vβ₃ expression. Cytotoxicity assay indicated that all cRGD peptides (0-200 µM) had at least 70-80% of viability in U87MG cells. Fluorescence images showed cRGD dimer peptides have the highest cellular internalization compare to cRGD monomer and cRGD tetramer peptides. Additionally, transmission electron microscope results clearly visualized the endocytic internalization of integrin α_vβ₃ receptors and correlated with confocal microscopic results. These results support the rationale for the use of cRGD dimer peptides for imaging, diagnosis, or therapy of integrin α_vβ₃-rich glioblastoma.

• Advances in nano research
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• 제15권2호
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• pp.105-111
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• 2023

Integrin αvβ3 is one of the receptors expressed in cancer cells. RGD peptides have the potential to target integrin αvβ3 (receptor), which can increase drug delivery efficiency. In this study, 55 different RGD dimer motifs were investigated. At first, the binding energy between RGD peptides and the receptor was calculated using molecular docking. Then, three RGD peptides with the strongest binding energy with the receptor were selected, and their dynamic adsorption on the receptor was simulated by molecular dynamics (MD). The obtained results showed that a sequence that has RGD at the beginning and end with tryptophan (TRP) has strong Lennard-Jones (LJ) and electrostatic interactions with Integrin αvβ3 and has changed the conformation of receptor significantly, which analyzed by root mean square deviation (RMSD) and radius of gyration.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.6073-6080
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• 2015

Background: Melanoma differentiation-associated gene-7 (MDA-7)/interleukin-24 (IL-24), a unique tumor suppressor gene, has killing activity in a broad spectrum of cancer cells. Herein, plasmids producing mda-7 proteins fused to different RGD peptides (full RGD4C and shortened RGD, tRGD) were evaluated for apoptosis induction with a hepatocellular carcinoma cell line, Hep-G2. The study aim was to improve the apoptosis potency of mda-7 by tethering to RGD peptides. Materials and Methods: Three plasmids including mda-7, mda-7-RGD and mda-7-tRGD genes beside a control vector were transfected into Hep-G2 cells. After 72 hours incubation, cell viability was evaluated by MTT assay. In addition, the rate of apoptosis was analyzed by flow cytometry using PI/annexin staining. To detect early events in apoptosis, 18 hours after transfection, expression of the BAX gene was quantified by real time PCR. Modeling of proteins was also performed to extrapolate possible consequences of RGD modification on their structures and subsequent attachment to receptors. Results and Conclusions: In MTT assays, while all mda-7 forms showed measurable inhibition of proliferation, unmodified mda-7 protein exhibited most significant effect compared to control plasmid (P<0.001). Again, flow cytometry analysis showed a significant apoptosis induction by simple mda-7 gene but not for those RGD-fused mda-7 proteins. These findings were also supported by expression analysis of BAX gene (P<0.001). Protein modelling analysis revealed that tethering RGD at the end of IL-24/Mda7 disrupt attachment to cognate receptor, IL-20R1/IL-20R2. In conclusion, fusion of RGD4C and shortened RGD peptides to carboxyl terminal of mda7, not only reduce apoptosis property in vitro but also disrupt receptor attachment as demonstrated by protein modelling.

• 방사선산업학회지
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• 제12권4호
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• pp.355-363
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• 2018

A novel $N_3S_1$ chelate, Pro-Lys-Cys (PKC) to cyclic RGD to radiolabel with $^{99m}Tc$ was conjugated in an effort to decrease the high intestinal accumulation observed for $^{99m}Tc$-labeled PGC-RGD. The target specificity of the resulting PKC-RGD was similar to that of PGC-RGD as determined by a cell binding assay and a competition binding assay. The $^{99m}Tc$ radiolabeling of PKC-RGD resulted in radiochemical yields of 98% under mild conditions at high specific activities. Biodistribution data in normal mice clearly showed a significant decrease in intestinal uptake at 2 h postinjection for the $^{99m}Tc-PKC-c$ (RGDyK) compared to the $^{99m}Tc-GC-c$ (RGDyK) (from $19.65%ID{\cdot}g^{-1}$ to $7.31%ID{\cdot}g^{-1}$ for the GI tract). The $^{99m}Tc-PKC-c$ (RGDyK) biodistribution was also shown by a higher retention of radioactivity in the whole body, but with kidney accumulation over 8-fold higher than observed with $^{99m}Tc-PGC-c$ (RGDyK) at 2 h ($12.62%ID{\cdot}g^{-1}$ for PKC-RGD and $1.54%ID{\cdot}g^{-1}$ for PGC-RGD, respectively). These results show that the biodistribution may be altered especially concerning lipophilicity resulting in renal rather than hepatobiliary excretion. This comparative study made it possible to explore the effects of lipophilicity on the biodistribution of $^{99m}Tc$-labeled c (RGDyK) through the use of different tripeptide $N_3S_1$ chelators. Therefore, $^{99m}Tc-PKC-c$ (RGDyK) may be an attractive alternative for the in vivo imaging of integrin receptors.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.268-268
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• 2006

Due to their multipotency, stem cells can differentiate into a variety of specialized cell types, such as chondrocytes, osteoblasts, myoblasts, and nerve cells. As an alternative to mature tissue cells, stem cells are of importance in tissue engineering and regenerative medicine. Since interactions between scaffold and cells play an important role in the tissue development in vitro, synthetic oligopeptides have been immobilized onto polymeric scaffolds to improve specific cell attachment and even to stimulate cell differentiation. In this study, chondrogenic differentiation of stem cells was evaluated using surface-modified PLLA scaffolds, i.e., either hydrophilic acrylic acid (AA)-grafted PLLA or RGD-immobilized one. Porous PLLA scaffolds were prepared using a gas foaming method, followed by plasma treatment and subsequent grafting of AA to introduce a hydrophilicity (PLLA-PAA). This was further processed to fix RGD peptide to make an RGD-immobilized scaffold (PLLA-PAA-RGD). Stem cells were seeded at $1{\times}10^{6}$ cells per scaffold and the cell-PLLA constructs were cultured for up to 4 weeks in the chondrogenic medium. Using these surface-modified scaffolds, adhesion, proliferation, and chondrogenic differentiation of stem cells were evaluated. The surface of PLLA scaffolds turned hydrophilic (water contact angle, 45 degrees) with both plasma treatment and AA grafting. The hydrophilicity of RGD-immobilized surface was not significantly altered. Cell proliferation rate on the either PLLA-PAA or PLLA-PAA-RGD surface was obviously improved, especially with the RGD-immobilized one as compared to the control PLLA one. Chondrogenic differentiation was clearly identified with Safranin O staining of GAG in the AA- or RGD-grafted PLLA substrates. This study demonstrated that modified polymer surfaces may provide better environment for chondrogenesis of stem cells.