Rat Articular Cartilages Change Their Tissue and Protein Compositions During Perinatal Period.

Articular cartilage (AC) covers the surface of bones in joints and functions as a cushion against mechanical loading. The tissue contains abundant extracellular matrix (ECM), which mainly consists of proteoglycans (PG) and collagen (COL) fibres. The property of AC is gradually changing by ageing with gravity loading. To know the property change of AC by initial gravity loading during short period after birth, we performed histological assays and proteomics assay on the AC of the femoral condyle in knee joints of perinatal rats. The water content (%) was significantly decreased in neonate AC compared with fetal AC. During the perinatal stages (E19 and P0), the localizations of glycosaminoglycan (GAG) and type I and II COLs were homogeneous. The density of chondrocytes was significantly decreased in the deeper layers comparing with the surface layer in neonate AC. In addition, we found a drastic change in the protein expression pattern on proteomic analysis. The expressions of ECM components were relatively increased in neonate AC compared with fetal AC.

Effect of tenascin-X together with vascular endothelial growth factor A on cell proliferation in cultured embryonic hearts.

Tenascin-X (TNX) is a large glycoprotein that appears in extracellular matrices. Previously, we demonstrated that TNX binds to vascular endothelial growth factors A and B (VEGF-A and -B) and that VEGF-B in combination with TNX induces DNA synthesis in endothelial cells via increased signals mediated by the VEGFR-1 receptor. In this study, we investigated the effect of TNX with VEGF-A on the cell proliferation in embryonic mouse heart explants from either wild-type (TNX+/+) or TNX-deficient (TNX-/-) mice. The addition of VEGF-A to the explants from TNX+/+ mice increased cell proliferation by 1.5 fold compared with that in TNX-/- mice, indicating that TNX with VEGF family member plays an important role in the control of endothelial cell proliferation in vivo.

Chemical states and lattice dynamics of alpha-diimine Fe2+ complexes intercalated into gamma-zirconium phosphate.

The alpha-diimine Fe2+ complexes, [Fe(phen)3]2+, [Fe(bpy)3]2+, and [Fe(terpy)2]2+, (phen: 1,10-phenanthroline, bpy: 2,2'-bipyridyl, terpy: alpha,alpha',alpha''-tripyridine) were intercalated into zirconium dihydrogenphosphate phosphate dihydrate (gamma-zirconium phosphate, gamma-ZrP), Zr(PO4)(H2PO4).2H2O. The rate of the intercalation, the molar ratio of Fe to Zr, was found to be 3.82-7.76%. Mössbauer spectra indicated that one part of [Fe(phen)3]2+ and [Fe(bpy)3]2+ changed from a low-spin Fe2+ to high-spin Fe2+ state on intercalation, but [Fe(terpy)2]2+ did not change in chemical state. The lattice dynamics of the complexes and the intercalation compounds were investigated in terms of the temperature dependence of the area intensity on the Mössbauer spectra. A linear relationship was established for all the complex salts and the intercalation compounds investigated between the ln[A(T)/A(82)] and absolute temperature, T, where A(T) and A(82) show the intensities of a doublet at T and 82 K of the Mössbauer spectra, respectively. From the slope of the linear relation, the theta2M values, which were derived based on the Debye approximation of lattice vibration, were evaluated for the complex salts and the intercalation compounds. The Fe2+ complexes showed theta2M values of 1.27 to 2.32 x 10(6), whereas the intercalation compounds showed very similar values to each other, ranging from 2.19 to 2.39 x 10(6), irrespective of different alpha-diimine ligands. The results were explained in terms of the characteristic layered structure of zirconium phosphate, and by the tight bond between the alpha-diimine Fe2+ complexes and the host gamma-ZrP.

Structures and comparison of genomic and complementary DNAs of mouse MSSP, a c-Myc binding protein.

Two cDNAs encoding mouse MSSP and Scr3 were cloned. Both proteins, like those in humans, share significant homology of the region near the N-terminus containing the RNA-binding protein, RNP, while little homology exists near the C-terminal region of the proteins. Expression of mouse MSSP and Scr3 in mouse tissues were examined by Northern blot hybridization and both mRNAs were ubiquitously expressed in all the tissues except for testis, where the smaller sizes of MSSP mRNAs, but not Scr3 mRNA, were highly expressed. Then, the genomic DNA of mouse MSSP was cloned. Mouse genomic MSSP gene was comprised of at least 13 exons over the region spanning 60 kb. Furthermore, a chromosome location of human MSSP gene was identified at 2q24 by FISH mapping.

Transcription factor Sp1 activates the expression of the mouse tenascin-X gene.

Tenascin-X (TNX) is an extracellular matrix protein that is prominent in the heart and muscle. We previously showed that TNX is expressed in fibroblast cells in culture. To elucidate the molecular basis of the TNX gene expression, the promoter region of the mouse TNX gene (mTnx) has been characterized. The two adjacent transcription initiation sites were identified at 68 and 67 bp upstream of the previously known 5'-untranslated exon. Transient transfection of L and 293T cells with 5'-deletion constructs of the promoter region linked to the luciferase reporter revealed that the region (-141 to -136) containing a transcription factor Sp1-binding element contributes to the expression of mTnx. Site-directed mutagenesis of the Sp1-binding region confirmed this result. Electrophoretic mobility shift analysis using nuclear extracts obtained from the cells demonstrated that a distinct Sp1-DNA complex is formed at the element. Our results show that Sp1 plays a critical role in the gene expression of mTnx.