Possible involvement of altered RGD sequence in reduced adhesive and spreading activities of advanced glycation end product-modified fibronectin to vascular smooth muscle cells

Skin wound healing in diabetic β6 integrin-deficient mice

Integrin αvβ6 is a heterodimeric cell surface receptor, which is absent from the normal epithelium, but is expressed in wound-edge keratinocytes during re-epithelialization. However, the function of the αvβ6 integrin in wound repair remains unclear. Impaired wound healing in patients with diabetes constitutes a major clinical problem worldwide and has been associated with the accumulation of advanced glycated endproducts (AGEs) in the tissues. AGEs may account for aberrant interactions between integrin receptors and their extracellular matrix ligands such as fibronectin (FN). In this study, we compared healing of experimental excisional skin wounds in wild-type (WT) and β6-knockout (β6(-/-) ) mice with streptozotocin-induced diabetes. Results showed that diabetic β6(-/-) mice had a significant delay in early wound closure rate compared with diabetic WT mice, suggesting that αvβ6 integrin may serve as a protective role in re-epithelialization of diabetic wounds. To mimic the glycosylated wound matrix, we generated a methylglyoxal (MG)-glycated variant of FN. Keratinocytes utilized αvβ6 and β1 integrins for spreading on both non-glycated and FN-MG, but their spreading was reduced on FN-MG. These findings indicated that glycation of FN and possibly other integrin ligands could hamper keratinocyte interactions with the provisional matrix proteins during re-epithelialization of diabetic wounds.

Evaluation of RGD Modification on Collagen Matrix

OBJECTIVE

To observe the changes during the process of modificating collagen with Arg-Gly-Asp (RGD) peptide, a series experiments were designed.

METHODS

The 3D porous collagen matrices modified with RGD peptide were constructed by lyophilization. The modified and unmodified matrices were characterized by Scanning Electron Microscopy (SEM) and Electron Spectroscopy for Chemical Analysis (ESCA). Fibroblasts were used to evaluate the cell compatibility of the matrices.

RESULTS

In terms of cell growth, the cells attached much better on the modified matrix than on the unmodified one. Compare to the unmodified matrices, the polar groups on the modified matrix increased.

CONCLUSIONS

The introducing of specific RGD receptor-mediated adhesion site on matrices obviously enhanced the cells adhesion on collagen matrices.

Impact of the non-cellular tumor microenvironment on metastasis: potential therapeutic and imaging opportunities

Evidence is accumulating that the malignant phenotype of a given tumor is dependent not only on the intrinsic characteristics of tumor cells, but also on the cooperative interactions of non-neoplastic cells, soluble secreted factors and the non-cellular solid-state ECM network that comprise the tumor microenvironment. Given the ability of the tumor microenvironment to regulate the cellular phenotype, recent efforts have focused on understanding the molecular mechanisms by which cells sense, assimilate, interpret, and ultimately respond to their immediate surroundings. Exciting new studies are beginning to unravel the complex interactions between the numerous cell types and regulatory factors within the tumor microenvironment that function cooperatively to control tumor cell invasion and metastasis. Here, we will focus on studies concerning a common theme, which is the central importance of the non-cellular solid-state compartment as a master regulator of the malignant phenotype. We will highlight the non-cellular solid-state compartment as a relatively untapped source of therapeutic and imaging targets and how cellular interactions with these targets may regulate tumor metastasis.

What Is the Future of Diabetic Wound Care?

With diabetes affecting 5% to 10% of the US population, development of a more effective treatment for chronic diabetic wounds is imperative. Clinically, the current treatment in topical wound management includes debridement, topical antibiotics, and a state-of-the-art topical dressing. State-of-the-art dressings are a multi-layer system that can include a collagen cellulose substrate, neonatal foreskin fibroblasts, growth factor containing cream, and a silicone sheet covering for moisture control. Wound healing time can be up to 20 weeks. The future of diabetic wound healing lies in the development of more effective artificial "smart" matrix skin substitutes. This review article will highlight the need for novel smart matrix therapies. These smart matrices will release a multitude of growth factors, cytokines, and bioactive peptide fragments in a temporally and spatially specific, event-driven manner. This timed and focal release of cytokines, enzymes, and pharmacological agents should promote optimal tissue regeneration and repair of full-thickness wounds. Development of these kinds of therapies will require multidisciplinary translational research teams. This review article outlines how current advances in proteomics and genomics can be incorporated into a multidisciplinary translational research approach for developing novel smart matrix dressings for ulcer treatment. With the recognition that the research approach will require both time and money, the best treatment approach is the prevention of diabetic ulcers through better foot care, education, and glycemic control.

Evaluation of modifying collagen matrix with RGD peptide through periodate oxidation

The aim of the study is to evaluate the effect of modifying collagen matrices with Arg-Gly-Asp (RGD) peptide through periodate oxidation. The collagen matrices were modified with RGD peptide, by periodate activation. The modified collagen matrices and unmodified matrices were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and electron spectroscopy for chemical analysis (ESCA). Mesenchymal stem cells (MSCs) were used to evaluate the cell compatibility of collagen matrices. In terms of cell growth, the MSCs attached much better on the modified matrix than on the unmodified one. But there was no significant difference between two groups regarding the MSC proliferation. Compared to the unmodified matrices, the mechanical strength of the modified matrix decreased sharply, and its 3D structure was destroyed. Introducing specific RGD receptor-mediated adhesion sites on matrices obviously enhanced the MSC adhesion on collagen matrices, but the coupled method of periodate oxidation would likely result in the declination of the mechanical strength of the matrix, as well as the destruction of the matrix structure. This would affect the cell growth on the matrix, and decrease the histocompatibility of the matrices.

Advanced glycation endproducts interfere with integrin-mediated osteoblastic attachment to a type-I collagen matrix

The adhesion of osteoblasts to bone extracellular matrix, of which type-I collagen constitutes >85%, can modulate diverse aspects of their physiology such as growth, differentiation and mineralisation. In this study we examined the adhesion of UMR106 rat osteoblast-like cells either to a control (Col) or advanced-glycation-endproduct-modified (AGEs-Col) type I collagen matrix. We investigated the possible role of different integrin receptors in osteoblastic adhesion, by co-incubating these cells either with beta-peptide (conserved sequence 113-125 of the beta subunit of integrins) or with two other peptides, RGD (Arg-Gly-Asp) and DGEA (Asp-Gly-Glu-Ala), which are recognition sequences for the alpha-subunits of alpha(1,5)beta(1) and alpha(2)beta(1) integrins. Collagen glycation inhibited the adhesion of UMR106 osteoblasts to the matrix (40% reduction versus Col, P > 0.001). beta-Peptide showed a dose- and glycation-dependent inhibitory effect on adhesion, and at a concentration of 100 microM decreased the attachment of UMR106 cells to both matrices (42% to Col, P<0.001and 25% to AGEs-Col, P<0.01). The synthetic peptides RGD (1mM) and DGEA (5mM) inhibited the attachment of UMR106 cells to Col (30 and 20%, P > 0.01 and P< 0.001, respectively), but not to AGEs-Col. beta-Peptide induced an increase in UMR106 cell clumping and a decrease in cellular spreading, while DGEA increased spreading with cellular extensions in multiple directions. These results indicate that both alpha and beta integrin subunits participate in osteoblastic attachment to type-I collagen, probably through the alpha(1,5)beta(1) and alpha(2)beta(1) integrins. AGEs-modification of type-I collagen impairs the integrin-mediated adhesion of osteoblastic cells to the matrix, and could thus contribute to the pathogenesis of diabetic osteopenia.

Identification and sequence analysis of mouse homologous gene coding for hepatitis C virus non-structural protein 5A-binding protein 37

AIM: To clone murine homologous gene to human NS5ABP37 gene, and to elucidate its biological functions and the possible effects in the pathogenesis of hepatitis C virus (HCV) infection.

METHODS: Yeast-two hybrid system was employed to screen the human liver cDNA library by using non-structural protein 5A (NS5A) of hepatitis C virus (HCV) as the bait. According to the homologous role between the species, a murine NS5ABP37 homologous to human NS5ABP37 was deduced by bioinformatics methods. The primary sequence of murine NS5ABP37 was searched for conserved domains by online tools of GeneBank.

RESULTS: Human NS5ABP37 was screened and cloned from human liver cDNA library by yeast-two hybrid system 3. The murine NS5ABP37 was deduced by bioinformatics methods. The open reading frame (ORF) of murine NS5ABP37 consisted of 1 488 nt encoding a protein of 495 amino acids. Calculated molecular weight was 54 583.67 dalton and predicted pI was 4.70. From the homologous protein search, murine NS5ABP37 was demonstrated homologous to leukocyte antigen related (LAR) protein precursor. The sequence of murine NS5ABP37 was deposited into GenBank, and the accession number was AY234860.

CONCLUSION: Successful identification and cloning of murine NS5ABP37, which is homologous to LAR protein precursor, paves a way for elucidating the biological function of murine NS5ABP37 and pathogenesis of hepatitis C virus infection.