Dual role for the latent transforming growth factor-beta binding protein in storage of latent TGF-beta in the extracellular matrix and as a structural matrix protein

The role of the latent TGF-beta binding protein (LTBP) is unclear. In cultures of fetal rat calvarial cells, which form mineralized bonelike nodules, both LTBP and the TGF-beta 1 precursor localized to large fibrillar structures in the extracellular matrix. The appearance of these fibrillar structures preceded the appearance of type I collagen fibers. Plasmin treatment abolished the fibrillar staining pattern for LTBP and released a complex containing both LTBP and TGF-beta. Antibodies and antisense oligonucleotides against LTBP inhibited the formation of mineralized bonelike nodules in long-term fetal rat calvarial cultures. Immunohistochemistry of fetal and adult rat bone confirmed a fibrillar staining pattern for LTBP in vivo. These findings, together with the known homology of LTBP to the fibrillin family of proteins, suggest a novel function for LTBP, in addition to its role in matrix storage of latent TGF-beta, as a structural matrix protein that may play a role in bone formation

Parathyroid hormone induces bone cell motility and loss of mature osteocyte phenotype through L-calcium channel dependent and independent mechanisms

Parathyroid Hormone (PTH) can exert both anabolic and catabolic effects on the skeleton, potentially through expression of the PTH type1 receptor (PTH1R), which is highly expressed in osteocytes. To determine the cellular and molecular mechanisms responsible, we examined the effects of PTH on osteoblast to osteocyte differentiation using primary osteocytes and the IDG-SW3 murine cell line, which differentiate from osteoblast to osteocyte-like cells in vitro and express GFP under control of the dentin matrix 1 (Dmp1) promoter. PTH treatment resulted in an increase in some osteoblast and early osteocyte markers and a decrease in mature osteocyte marker expression. The gene expression profile of PTH-treated Day 28 IDG-SW3 cells was similar to PTH treated primary osteocytes. PTH treatment induced striking changes in the morphology of the Dmp1-GFP positive cells in IDG-SW3 cultures and primary cells from Dmp1-GFP transgenic mice. The cells changed from a more dendritic to an elongated morphology and showed increased cell motility. E11/gp38 has been shown to be important for cell migration, however, deletion of the E11/gp38/podoplanin gene had no effect on PTH-induced motility. The effects of PTH on motility were reproduced using cAMP, but not with protein kinase A (PKA), exchange proteins activated by cAMP (Epac), protein kinase C (PKC) or phosphatidylinositol-4,5-bisphosphonate 3-kinase (Pi3K) agonists nor were they blocked by their antagonists. However, the effects of PTH were mediated through calcium signaling, specifically through L-type channels normally expressed in osteoblasts but decreased in osteocytes. PTH was shown to increase expression of this channel, but decrease the T-type channel that is normally more highly expressed in osteocytes. Inhibition of L-type calcium channel activity attenuated the effects of PTH on cell morphology and motility but did not prevent the downregulation of mature osteocyte marker expression. Taken together, these results show that PTH induces loss of the mature osteocyte phenotype and promotes the motility of these cells. These two effects are mediated through different mechanisms. The loss of phenotype effect is independent and the cell motility effect is dependent on calcium signaling.Matthew Prideaux, Sarah L. Dallas, Ning Zhao, Erica D. Johnsrud, Patricia A. Veno, Dayong Guo, Yuji Mishina, Stephen E. Harris, Lynda F. Bonewal

Drying colloidal systems: laboratory models for a wide range of applications

The drying of complex fluids provides a powerful insight into phenomena that take place on time and length scales not normally accessible. An important feature of complex fluids, colloidal dispersions and polymer solutions is their high sensitivity to weak external actions. Thus, the drying of complex fluids involves a large number of physical and chemical processes. The scope of this review is the capacity to tune such systems to reproduce and explore specific properties in a physics laboratory. A wide variety of systems are presented, ranging from functional coatings, food science, cosmetology, medical diagnostics and forensics to geophysics and art

Evolution during wine aging of colour and tannin differences induced by wine starters

The ability of threeSaccharomyces cerevisiae strains, with different colour adsorption aptitude, to induce and maintain colour differences in wines obtained from the Calabrian Gaglioppo and Magliocco black grape varieties was studied during one year of aging. The evolution of wine tannin content was also considered. Total polyphenols, colour parameters and total tannin values exhibited, both for Gaglioppo and Magliocco wines, significant (P < 0.05) or highly significant (P < 0.01) differences among strains. It is interesting to note that yeasts appear to exhibit a different adsorption aptitude for anthocyanins and tannins. The strain that gave wine with high values for the colour parameters was not the same as the one that produced wine with high values of tannins. The obtained results suggest that the choice of yeast strain in winemaking affects, in a significant way, the phenolic composition of wines with direct consequences on their colour and tannin content. Moreover, the interaction between grape cultivar and yeast is close and important, because grape variety, due to its phenolic composition, modulates yeast strain adsorption activity