Background: Polydom/SVEP1 is a putative extracellular matrix protein of unknown function. Results: Polydom/SVEP1 is a potent ligand for integrin ␣91 and colocalizes with the integrin in vivo. Conclusion: Polydom/SVEP1 is a hitherto unknown high affinity ligand for integrin ␣91. Significance: The identification of this high affinity ligand offers important clues toward better understanding of the consequences of integrin ␣91-mediated cell-extracellular matrix interactions.
Changes in several components and properties were examined to find appropriate indicators of freshness of common squid during storage at o"C, 5°C and 10°C. Total viable counts of bacteria, pH and volatile basic nitrogen did not change significantly during 2 wk storage at 0°C. Unlike usual fish meat, Kvalue in squid muscle changed very quickly, but Hx/AMP ratio was a better indicator. Agmatine increased before initial decomposition started but was not suitable as an early freshness indicator. Free basic amino acids, arginine and ornithine also changed rapidly. Basic amino acids such as arginine and ornithine appeared to be appropriate indicators of freshness of common squid.
The present study was carried out to examine the effects of valproic acid (VPA), a histone deacetylase inhibitor, on in vitro development of miniature pig somatic cell nuclear transfer (SCNT) embryos and on expression of a mouse Oct-3/4 promoter-driven enhanced green fluorescent protein (EGFP) gene (EGFP expression only detected in Oct-3/4-expressing cells) introduced into donor cells for SCNT during their development. The addition of 4 mM VPA to embryo culture medium for 48 h after activation significantly (p < 0.01) increased the blastocyst formation rate of SCNT embryos compared with the control, whereas VPA did not affect their cleavage rate. The rate of SCNT embryos expressing EGFP at 5 days of culture was not affected by the presence or absence of VPA treatment. At 7 days of culture, however, the addition of 4 mM VPA to embryo culture medium for 48 h after activation significantly (p < 0.05) increased the rate of SCNT embryos expressing EGFP compared with the control. The results indicate that VPA enhances the ability of miniature pig SCNT embryos to develop into blastocysts and maintains the ability of them to express Oct-3/4 gene.
␣v8 is an integrin that recognizes an Arg-Gly-Asp (RGD) motif and interacts with fibronectin, vitronectin, and latent TGF-1. We comprehensively determined the binding activity of the ␣v8 integrin toward 25 secreted proteins having an RGD motif. The ␣v8 integrin strongly bound to latent TGF-1 but showed marginal activity for other RGD-containing proteins, including fibronectin and vitronectin. Site-directed mutagenesis of latent TGF-1 demonstrated that the high affinity binding of ␣v8 integrin to latent TGF-1 was defined by Leu-218 immediately following the RGD motif within the latency-associated peptide of TGF-1. Consistent with the critical role of Leu-218 in latent TGF-1 recognition by ␣v8 integrin, a 9-mer synthetic peptide containing an RGDL sequence strongly inhibited interactions of latent TGF-1 with ␣v8 integrin, whereas a 9-mer peptide with an RGDA sequence was ϳ60-fold less inhibitory. Because ␣v3 integrin did not exhibit strong binding to latent TGF-1 or distinguish between RGDL-and RGDA-containing peptides, we explored the mechanism by which the integrin 8 subunit defines the high affinity binding of latent TGF-1 by ␣v8 integrin. Production of a series of swap mutants of integrin 8 and 3 subunits indicated that the high affinity binding of ␣v8 integrin with latent TGF-1 was ensured by interactions between the Leu-218 residue and the 8 I-like domain, with the former serving as an auxiliary recognition residue defining the restricted ligand specificity of ␣v8 integrin toward latent TGF-1. In support of this conclusion, high affinity binding toward the ␣v8 integrin was conferred on fibronectin by substitution of its RGDS motif with an RGDL sequence.Integrins are a family of adhesion receptors that bind to a variety of extracellular ligands, typically cell adhesion proteins in the extracellular matrix (ECM).2 Integrins play mandatory roles in embryonic development and the maintenance of tissue architecture by providing essential links between cells and the ECM (1). Integrins are composed of two non-covalently associated subunits, termed ␣ and . In mammals, 18 ␣ and 8  subunits have been identified, and combinations of these subunits give rise to at least 24 distinct integrin heterodimers, among which 18 isoforms function as ECM receptors. Based on their ligand binding specificities, ECM-binding integrins are classified into three major groups as follows: laminin-, collagen-, and Arg-Gly-Asp (RGD)-binding integrins (1, 2), of which the RGD-binding integrins have been most extensively investigated. The RGD-binding integrins include ␣51, ␣81, ␣IIb3, and ␣v-containing integrins, which interact with a variety of ECM ligands containing RGD motifs with distinct binding specificities.The integrin ␣v subunit was originally identified as a receptor for vitronectin (3). The ␣v-containing integrins are widely expressed on many cell types, including neural crest cells, glial cells, muscle cells, osteoclasts, epithelial cells, and vascular endothelial cells during embryonic development (4...
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