In vitro expression analysis of collagen biosynthesis and assembly

The main product of specialized tissues regulates cell life and may cause neoplastic transformation

Many tissues and cells in vertebrates are highly specialized and devoted to a single function through the action of a single molecule, that we call the "main product" (MP) of the cell. The hypothesis here proposed is that these MPs control all aspects of the cell life, namely activity, division, differentiation and apoptosis. Evidences supporting this hypothesis are reported for the immune system, pancreatic beta-cells, melanocytes, connective tissues, thyroid cells, skin and erythroid cells. In all cases cell division and differentiation is promoted by a normal activity of the MP, while hyperactivity leads to cell apoptosis. Evidences are also provided that alterations of the activity of the MP may elicit pathological disorders; in particular mutations altering the structure of the MP may elicit tumoural transformation.

Effects of collagen matrix on Sindbis virus infection of BHK cells

The effects of extracellular matrix (ECM) components on the outcomes of alphavirus interaction with cells are not known. Studies that address such interactions have to address several methodological difficulties, including: the survival of the cells within the matrix; the passage of the virus through the matrix to infect embedded cells; and the dissociation of cells and matrix into single-cell suspension, before and after virus infection, for quantitative analysis. Herein, these issues were addressed in the context of a model system of collagen as the ECM component, baby hamster kidney (BHK) cells, and Sindbis virus. The outcomes of Sindbis virus infection of BHK cells, grown in three-dimensional (3D) collagen gel versus on plastic, and on two-dimensional (2D) collagen versus bovine serum albumin (BSA)-coated surfaces were compared. Cell morphology was more slender in 3D and on 2D collagen than on plastic or BSA-coated surfaces. The cells were able to survive in the 3D environment. Using Sindbis virus carrying the green fluorescent protein gene, the virions were found to be capable of penetrating the 3D collagen matrix and infecting the cells. There was more infectious virus in cultures of cells in 3D and on 2D collagen than on plastic or BSA-coated surfaces, respectively. Higher virus titers from cells on 2D collagen compared to BSA-coated surfaces was not associated with uninfected cell number or viability but with increased cell survival after infection. Infected cells on BSA surfaces became detached, while those on 2D collagen remained attached. These experiments establish procedures for analysis of interaction of collagen, BHK cells, and Sindbis virus and suggest that collagen increases infectious Sindbis virus titers from BHK cells by enhancing post-infection cell survival.

A dominant interference collagen X mutation disrupts hypertrophic chondrocyte pericellular matrix and glycosaminoglycan and proteoglycan distribution in transgenic mice

Collagen X transgenic (Tg) mice displayed skeleto-hematopoietic defects in tissues derived by endochondral skeletogenesis.(1) Here we demonstrate that co-expression of the transgene product containing truncated chicken collagen X with full-length mouse collagen X in a cell-free translation system yielded chicken-mouse hybrid trimers and truncated chicken homotrimers; this indicated that the mutant could assemble with endogenous collagen X and thus had potential for dominant interference. Moreover, species-specific collagen X antibodies co-localized the transgene product with endogenous collagen X to hypertrophic cartilage in growth plates and ossification centers; proliferative chondrocytes also stained diffusely. Electron microscopy revealed a disrupted hexagonal lattice network in the hypertrophic chondrocyte pericellular matrix in Tg growth plates, as well as altered mineral deposition. Ruthenium hexamine trichloride-positive aggregates, likely glycosaminoglycans (GAGs)/proteoglycans (PGs), were also dispersed throughout the chondro-osseous junction. These defects likely resulted from transgene co-localization and dominant interference with endogenous collagen X. Moreover, altered GAG/PG distribution in growth plates of both collagen X Tg and null mice was confirmed by a paucity of staining for hyaluronan and heparan sulfate PG. A provocative hypothesis links the disruption of the collagen X pericellular network and GAG/PG decompartmentalization to the potential locus for hematopoietic failure in the collagen X mice.

Use of Bombyx mori silk fibroin as a substratum for cultivation of animal cells

The growth of animal cells on silk fibroin-coated plates was examined. The anchorage-dependent cells showed almost the same growth on both fibroin- and collagen-coated plates, and it was 30-50% higher than that on polystyrene plates coated with hydrophilic groups. On the other hand, the growth of the anchorage-independent hybridomas on the three different plates did not show a significant difference. The cells grown on the respective plates produced their products with the same efficiency despite the difference in the chemical properties of the plates. In this paper, it is demonstrated that silk fibroin can be used as the substratum for the culture of animal cells in place of collagen.