Tissue remodeling in Guinea pig lateral prostate at different ages after estradiol treatment

Estrogen seems to have an essential role in the fibromuscular growth characteristic of benign prostatic hyperplasia (BPH). This paper describes the effects of chronic estradiol treatment on Guinea pig prostatic stroma at different ages. Tissues from experimental animals were studied by histological and histochemical procedures, morphometric-stereological analysis and transmission electron microscopy (TEM). Marked fibromuscular hypertrophy was observed after estradiol treatment in animals of pre-pubertal and adult ages. Increases in the density and thickness of the collagen and elastic fibers were observed by histochemistry. TEM revealed wide distributions of collagen fibrils and large elastic fibers adjacent to the epithelial basal lamina and between the stromal cells, establishing contacts between them. These results indicate that the Guinea pig prostate simulates the stromal modifications observed in BPH in some aged animals after estrogen treatment at different ages, making it a good model for this disease.     

Global gene expression profiling and cluster analysis in Xenopus laevis

We have undertaken a large-scale microarray gene expression analysis using cDNAs corresponding to 21,000 Xenopus laevis ESTs. mRNAs from 37 samples, including embryos and adult organs, were profiled. Cluster analysis of embryos of different stages was carried out and revealed expected affinities between gastrulae and neurulae, as well as between advanced neurulae and tadpoles, while egg and feeding larvae were clearly separated. Cluster analysis of adult organs showed some unexpected tissue-relatedness, e.g. kidney is more related to endodermal than to mesodermal tissues and the brain is separated from other neuroectodermal derivatives. Cluster analysis of genes revealed major phases of co-ordinate gene expression between egg and adult stages. During the maternal-early embryonic phase, genes maintaining a rapidly dividing cell state are predominantly expressed (cell cycle regulators, chromatin proteins). Genes involved in protein biosynthesis are progressively induced from mid-embryogenesis onwards. The larval-adult phase is characterised by expression of genes involved in metabolism and terminal differentiation. Thirteen potential synexpression groups were identified, which encompass components of diverse molecular processes or supra-molecular structures, including chromatin, RNA processing and nucleolar function, cell cycle, respiratory chain/Krebs cycle, protein biosynthesis, endoplasmic reticulum, vesicle transport, synaptic vesicle, microtubule, intermediate filament, epithelial proteins and collagen. Data filtering identified genes with potential stage-, region- and organ-specific expression. The dataset was assembled in the iChip microarray database, , which allows user-defined queries. The study provides insights into the higher order of vertebrate gene expression, identifies synexpression groups and marker genes, and makes predictions for the biological role of numerous uncharacterized genes.     

Role of water content in dielectric properties and delayed luminescence of bovine Achilles' tendon

In order to investigate the role of water network in collagen structure, measurement of dielectric permittivity was performed on bovine Achilles' tendon as a function of water content. The data show a sudden decrease of the permittivity at each measured frequency value when the tendon humidity decreases. A similar behaviour is shown by the total number of photons emitted in delayed luminescence (DL) experiments. The comparison of the two results is in agreement with the hypothesis that DL is connected to the excitation and subsequent decay of collective electronic states, whose properties depend on the organized structure of the system.     

Adiponectin inhibits the binding of low-density lipoprotein to biglycan, a vascular proteoglycan

The aim of this study was to test the possibility that adiponectin has an antiatherogenic effect through the inhibition of LDL binding to proteoglycans, an initial event in atherogenesis. Both full-length and globular adiponectin inhibited LDL binding in a dose-dependent manner. Both types of adiponectin bound to biglycan in a dose-dependent manner. Immunoprecipitation and immunoblotting analysis showed interaction of full-length adiponectin with LDL. Pretreatment of biglycan with globular adiponectin prior to LDL addition diminished the inhibitory effect, while pretreatment with full-length adiponectin retained the effect. This is a new antiatherogenic property that appears independent of the receptor-mediated hormonal action of adiponectin.     

Single amino acid substitutions in the C-terminus of collagen II alter its affinity for collagen IX

The structural integrity of cartilage depends on the presence of extracellular matrices (ECM) formed by heterotypic fibrils composed of collagen II, collagen IX, and collagen XI. The formation of these fibrils depends on the site-specific binding between relatively small regions of interacting collagen molecules. Single amino acid substitutions in collagen II change the physicochemical and structural characteristics of those sites, thereby leading to an alteration of intermolecular collagen II/collagen IX interaction. Employing a biosensor to study interactions between R75C, R789C or G853E collagen II mutants and collagen IX, we demonstrated significant changes in the binding affinities. Moreover, analyses of computer models representing mutation sites defined exact changes in physicochemical characteristics of collagen II mutants. Our study shows that changes in collagen II/collagen IX affinity could represent one of the steps in a cascade of changes occurring in the ECM of cartilage as a result of single amino acid substitutions in collagen II.     

Intracellular trafficking and degradation of unassociated proalpha2 chains of collagen type I

Procollagen I is a trimer consisting of two proalpha1(I) chains and one proalpha 2(I) chain. In certain cases of mild osteogenesis imperfecta, abnormal proalpha1(I) chains are degraded very soon after synthesis. As a consequence, the cells produce excess proalpha2(I) chains, which cannot form trimers and are not secreted. The objective of this work was to determine the intracellular fate of unassociated proalpha2(I) chains. Mov13 mouse fibroblasts, which do not synthesize proalpha1(I) mRNA, but do produce proalpha2(I) mRNA, were incubated with radioactive amino acids using pulse-chase protocols, and proteins were analyzed by gel electrophoresis, autoradiography, and Western blotting. Mov13 cells produced proalpha2(I) chains that were degraded intracellularly within 30 min. Degradation was inhibited when cells were treated with brefeldin-A, which blocks transit from endoplasmic reticulum to Golgi. Fixed cells exposed to various immunofluorescence markers and imaged by confocal laser scanning microscopy showed that proalpha2(I) chains colocalized with Golgi and lysosome markers. Degradation was inhibited and chains were secreted when cells were treated with wortmannin, which blocks trafficking to lysosomes. These results demonstrate that unassociated proalpha2(I) chains leave the endoplasmic reticulum, transit the Golgi, and enter lysosomes where they are degraded.     

Molecular and cellular events at the site of myocardial infarction: from the perspective of rebuilding myocardial tissue

The potential for bone marrow-derived progenitor cells (BMDPC) to regenerate myocardial tissue following infarction depends on homing, migration, nourishment, and spatially appropriate growth of BMDPC. Requisite to these objectives is the expression of adhesion molecules (ICAM-1) and chemoattractant cytokines (MCP-1), matrix metalloproteinase (MMP) activity, a neovasculature, and fibrillar collagen scaffolding. We found that enhanced ICAM-l and MCP-1, as well as MMP activity on day 3 and 7 postMI, are present to facilitate the homing, chemotaxis, and migration of circulating cells into the infarct site. The vascular network formed at the infarct site contains a ratio of conduit to exchange vessels that is greater than that for control tissue and therefore its ability to nourish BMDPC for their growth appears to be tenuous. These findings, together with the dense formation of a fibrillar collagen scar beyond week 2, suggest the optimal time to rebuild myocardium from BMDPC resides within 2 week postMI.     

A bioactive collagen-β tricalcium phosphate scaffold for tissue engineering

Collagen-phosphate composites (COL/β-TCP) are novel materials that have the potential to be used as bone analogues. The aim of our study was to develop a porous bioactive material composed of type I collagen, the main bone protein and tricalcium phosphate, the mineral phase of natural bone, and investigate their in vitro biocompatibility in a human dermal fibroblast culture system. In order to obtain the bioactive materials, type I collagen was isolated from bovine tendon and characterized by physicochemical methods. β-TCP was obtained from calcium carbonate by thermal decomposition at 900 °C temperature. The powder was examined with X-ray diffraction. Two variants of COL/β-TCP scaffolds (P1 and P2) were prepared and examined by scanning electron microscopy. Our results revealed a microporous structure with small white aggregates of β-TCP, non-homogenous scattered in the collagen framework without any preferential orientation. The biocompatibility of the obtained scaffolds was tested by biochemical and histological methods on human fibroblast cultures. Both materials acted as good subtrates for human dermal fibroblast proliferation and migration.     

The Streptococcal Binding Site in the Gelatin-binding Domain of Fibronectin Is Consistent with a Non-linear Arrangement of Modules

Fibronectin-binding proteins (FnBPs) of Staphylococcus aureus and Streptococcus pyogenes mediate invasion of human endothelial and epithelial cells in a process likely to aid the persistence and/or dissemination of infection. In addition to binding sites for the N-terminal domain (NTD) of fibronectin (Fn), a number of streptococcal FnBPs also contain an upstream region (UR) that is closely associated with an NTD-binding region; UR binds to the adjacent gelatin-binding domain (GBD) of Fn. Previously, UR was shown to be required for efficient streptococcal invasion of epithelial cells. Here we show, using a Streptococcus zooepidemicus FnBP, that the UR-binding site in GBD resides largely in the ⁸F1⁹F1 module pair. We also show that UR inhibits binding of a peptide from the α1 chain of type I collagen to ⁸F1⁹F1 and that UR binding to ⁸F1 is likely to occur through anti-parallel β-zipper formation. Thus, we propose that streptococcal proteins that contain adjacent NTD- and GBD-binding sites form a highly unusual extended tandem β-zipper that spans the two domains and mediates high affinity binding to Fn through a large intermolecular interface. The proximity of the UR- and NTD-binding sequences in streptococcal FnBPs is consistent with a non-linear arrangement of modules in the tertiary structure of the GBD of Fn.     

Type IIB Procollagen NH2-propeptide Induces Death of Tumor Cells via Interaction with Integrins αVβ3 and αVβ5

Cartilage is resistant to tumor invasion. In the present study, we found that the NH₂-propeptide of the cartilage-characteristic collagen, type IIB, PIIBNP, is capable of killing tumor cells. The NH₂-propeptide is liberated into the extracellular matrix prior to deposition of the collagen fibrils. This peptide adheres to and kills cells from chondrosarcoma and cervical and breast cancer cell lines via the integrins α_vβ₅ and α_vβ₃. Adhesion is abrogated by blocking with anti α_vβ₅ and α_vβ₃ antibodies. When α_v is suppressed by small intefering RNA, adhesion and cell killing are blocked. Normal chondrocytes from developing cartilage do not express α_vβ₃ and α_vβ₅ integrins and are thus protected from cell death. Morphological, DNA, and biochemical evidence indicates that the cell death is not by apoptosis but probably by necrosis. In an assay for invasion, PIIBNP reduced the number of cells crossing the membrane. In vivo, in a tumor model for breast cancer, PIIBNP was consistently able to reduce the size of the tumor.