A Newly Established Cell Line from Normal Human Bone Responds to 1alpha, 25-Dihydroxyvitamin D3, Retinoic Acid and Transforming Growth Factor-beta1

We have recently established a new osteoblastic cell line, designated SV-HFO, from normal human bone by immortalization with simian virus 40. In the present study, we examined the effects of diffusive factors on the expression of osteoblastic phenotype in SV-HFO cell line. lα, 25-dihydroxyvitamin D? in-duced the expression of alkaline phosphatase (ALP) and osteocalcin. Retinoic acid down-regulated the expression of ALP, whereas it up-regulated the expres-sion of osteocalcin. Transforming growth factor-β?, reduced the expression of both osteoblastic properties. These effects were time- and dose-dependent. These results show that the SV-HFO cell line maintains responsiveness to these diffusive factors. This cell line is suitable model for studying both metabolism and multistep carcinogenesis of human bone

Effects of the Protein Phosphatase Inhibitors, Okadaic Acid and Vanadate, on Localization of Occludin in Primary Cultures of Rat Hepatocytes

To elucidate whether protein phosphorylation is associated with the loca-lization of the tight junction protein occludin, we determined the changes of occludin protein expression in primary cultures of rat hepatocytes after treat-ment with the protein phosphatase inhibitors okadaic acid and vanadate. After 2 h of treatment with 1myu M okadaic acid or 5 mM vanadate, occludin immunoreactivity showing continuous lines in non-treated cells changed to a few spots on the plasma membrane. In western blots, broad bands above the occludin protein (65 kD) became conspicuous after treatment with okadaic acid and vanadate. We treated the same samples with alkaline phosphatase to examine whether the broad bands depended on the changes in the phos-phorylation states of occludin protein. The broad bands disappeared and the occludin was observed as a narrow band corresponding to 65 kD. Neither a significant change in the mRNA of occludin nor a change in the immunoreac-tivity of the tight junction associated protein, ZO-1, was observed after treatment with okadaic acid or vanadate. These results suggested that the phosphorylation of occludin is closely associated with localization of the protein in cultured hepatocytes and that protein phosphatase inhibitors affect the loca-lization of occludin but not ZO-1 on the plasma membrane

Structure and properties of densified silica glass: characterizing the order within disorder

世界一構造秩序のあるガラスの合成と構造解析に成功 --ガラスの一見無秩序な構造の中に潜む秩序を抽出--. 京都大学プレスリリース. 2021-12-25.The broken symmetry in the atomic-scale ordering of glassy versus crystalline solids leads to a daunting challenge to provide suitable metrics for describing the order within disorder, especially on length scales beyond the nearest neighbor that are characterized by rich structural complexity. Here, we address this challenge for silica, a canonical network-forming glass, by using hot versus cold compression to (i) systematically increase the structural ordering after densification and (ii) prepare two glasses with the same high-density but contrasting structures. The structure was measured by high-energy X-ray and neutron diffraction, and atomistic models were generated that reproduce the experimental results. The vibrational and thermodynamic properties of the glasses were probed by using inelastic neutron scattering and calorimetry, respectively. Traditional measures of amorphous structures show relatively subtle changes upon compacting the glass. The method of persistent homology identifies, however, distinct features in the network topology that change as the initially open structure of the glass is collapsed. The results for the same high-density glasses show that the nature of structural disorder does impact the heat capacity and boson peak in the low-frequency dynamical spectra. Densification is discussed in terms of the loss of locally favored tetrahedral structures comprising oxygen-decorated SiSi4 tetrahedra

The role of osteopontin in tendon tissue remodeling after denervation-induced mechanical stress deprivation

It has been shown that musculoskeletal tissues undergo dynamic tissue remodeling by a process that is quite sensitive to the mechanical environment. However, the detailed molecular mechanism underlying this process remains unclear. We demonstrate here that after denervation-induced mechanical stress deprivation, tendons undergo dynamic tissue remodeling as evidenced by a significant reduction of the collagen fibril diameter. Importantly, the transient up-regulation of osteopontin (OPN) expression was characteristic during the early phase of tendon tissue remodeling. Following this dynamic change of OPN expression, matrix metalloproteinase (MMP)-13 expression was induced, which presumably accounts for the morphological changes of tendon by degrading tendon collagen fibrils. The modulation of MMP-13 expression by OPN was specific, since the expression of MMP-2, which is also known to be involved in tissue remodeling, did not alter in the tendons under the absence or presence of OPN. We also demonstrate that the modulation of MMP-13 expression by OPN is due to the signaling through cell surface receptors for OPN. Thus, we conclude that OPN plays a crucial role in conveying the effect of denervation-induced mechanical stress deprivation to the tendon fibroblasts to degrade the extracellular matrices by regulating MMP-13 expression in tendon fibroblasts