Protein Polysaccharides from Bovine Nasal Cartilage Interactions with Glycoproteins and the Formation of Aggregates

Proteinpolysaccharides are macromolecules which consist primarily of chondroitin-4-sulfate associated with non-collagenous protein. They constitute about half of the dry weight of adult bovine nasal cartilage; the remaining material is predominantly collagen

The effect of cathepsins from varied sources on proteinpolysaccharide (PP-L) of bovine costal cartilage and on proteoglycan subunit (PGS) of bovine nasal cartilage

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48001/1/223_2005_Article_BF02152353.pd

Nuclear hyaluronidase 2 drives alternative splicing of CD44 pre-mRNA to determine profibrotic or antifibrotic cell phenotype

The cell surface protein CD44 is involved in diverse physiological processes, and its aberrant function is linked to various pathologies such as cancer, immune dysregulation, and fibrosis. The diversity of CD44 biological activity is partly conferred by the generation of distinct CD44 isoforms through alternative splicing. We identified an unexpected function for the ubiquitous hyaluronan-degrading enzyme, hyaluronidase 2 (HYAL2), as a regulator of CD44 splicing. Standard CD44 is associated with fibrotic disease, and its production is promoted through serine-arginine–rich (SR) protein–mediated exon exclusion. HYAL2 nuclear translocation was stimulated by bone morphogenetic protein 7, which inhibits the myofibroblast phenotype. Nuclear HYAL2 displaced SR proteins from the spliceosome, thus enabling HYAL2, spliceosome components (U1 and U2 small nuclear ribonucleoproteins), and CD44 pre-mRNA to form a complex. This prevented double-exon splicing and facilitated the inclusion of CD44 exons 11 and 12, which promoted the accumulation of the antifibrotic CD44 isoform CD44v7/8 at the cell surface. These data demonstrate previously undescribed mechanisms regulating CD44 alternative splicing events that are relevant to the regulation of cellular phenotypes in progressive fibrosis

The effect of proteoglycans on the formation of fibrils from collagen solutions

The precipitation of collagen fibrils from solutions at 37 [deg]C and approximately physiological pH and ionic strength is retarded markedly in the presence of small amounts of proteoglycan monomer (PGS), proteoglycan aggregate (PGC), reduced and alkylated PGS, or cyanogen bromide-cleavage products of PGS. The polysaccharide-peptide fragments produced from PGS with papain, trypsin, cathepsin D, or the protein core obtained by the digestion of PGS with chondroitinase ABC are ineffective in this regard. In the presence of the materials which affected the rate of precipitation of the collagen fibrils, the specific absorbance, [Delta]Asp, of the collagen gels was directly related to specific retardation, Rsp, when the ratio of proteoglycan to collagen was less than 25 [mu]g/mg, suggesting that the size and/or organization of the fibrils in the gels was dependent on the presence of proteoglycans. PGS binds to collagen if it is present in the solution before the collagen fibrils form and at a maximum of about 1 molecule of PGS for every 25-30 molecules of collagen. Although the protein core of PGS does not retard fibrillogenesis, it does bind to collagen and does so even in the presence of PGS. The data support the thesis that the organization of collagen fibrils in tissues may be related to amounts and kinds of proteoglycans in the tissues.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22193/1/0000624.pd

Hyaluronidase-2 regulates RhoA signalling, myofibroblast contractility and other key pro-fibrotic myofibroblast functions

Hyaluronidase-2 (HYAL2) is a weak, acid-active hyaluronan-degrading enzyme that is broadly expressed in somatic tissues. Aberrant HYAL2 expression is implicated in diverse pathology. However, a significant proportion of HYAL2 is enzymatically inactive, thus the mechanisms through which HYAL2 dysregulation influences pathobiology is unclear. Recently, non-enzymatic HYAL2 functions have been described and our group has shown that nuclear HYAL2 can influence mRNA splicing to prevent myofibroblast differentiation. Myofibroblasts drive fibrosis, thereby promoting progressive tissue damage and leading to multimorbidity. This study identifies a novel HYAL2 cytoplasmic function in myofibroblasts that is unrelated to its enzymatic activity. In fibroblasts and myofibroblasts HYAL2 interacts with the small GTPase signaling molecule, RhoA. Transforming Growth Factor (TGF)-β1-driven fibroblast-to-myofibroblast differentiation promotes HYAL2 cytoplasmic re-localization to bind to the actin cytoskeleton. Cytoskeletal-bound HYAL2 functions as a key regulator of downstream RhoA signaling and influences pro-fibrotic myofibroblast functions including myosin light-chain kinase (MLCK) mediated myofibroblast contractility, myofibroblast migration, myofibroblast collagen/fibronectin deposition, as well as connective tissue growth factor (CTGF/CCN2) and matrix metalloproteinase-2 (MMP2) expression. These data demonstrate that in certain biological contexts the non-enzymatic effects of HYAL2 are critical in orchestrating RhoA signaling and downstream pathways that are important for full pro-fibrotic myofibroblast functionality. In conjunction with previous data demonstrating the influence of HYAL2 on RNA splicing, these findings begin to explain the broad biological effects of HYAL2

A preformed basal lamina alters the metabolism and distribution of hyaluronan in epidermal keratinocyte "organotypic" cultures grown on collagen matrices

A rat epidermal keratinocyte (REK) line which exhibits histodifferentiation nearly identical to the native epidermis when cultured at an air–liquid interface was used to study the metabolism of hyaluronan, the major intercellular macromolecule present in basal and spinous cell layers. Two different support matrices were used: reconstituted collagen fibrils with and without a covering basal lamina previously deposited by canine kidney cells. REKs formed a stratified squamous, keratinized epithelium on both support matrices. Hyaluronan and its receptor, CD44, colocalized in the basal and spinous layers similar to their distribution in the native epidermis. Most (approximately 75%) of the hyaluronan was retained in the epithelium when a basal lamina was present while most (approximately 80%) diffused out of the epithelium in its absence. While REKs on the two matrices synthesized hyaluronan at essentially the same rate, catabolism of this macromolecule was much higher in the epithelium on the basal lamina (half-life approximately 1 day, similar to its half-life in native human epidermis). The formation of a true epidermal compartment in culture bounded by the cornified layer on the surface and the basal lamina subjacent to the basal cells provides a good model within which to study epidermal metabolism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42232/1/418-113-4-265_s004180000128.pd

Age-related differences in human skin proteoglycans

Previous work has shown that versican, decorin and a catabolic fragment of decorin, termed decorunt, are the most abundant proteoglycans in human skin. Further analysis of versican indicates that four major core protein species are present in human skin at all ages examined from fetal to adult. Two of these are identified as the V0 and V1 isoforms, with the latter predominating. The other two species are catabolic fragments of V0 and V1, which have the amino acid sequence DPEAAE as their carboxyl terminus. Although the core proteins of human skin versican show no major age-related differences, the glycosaminoglycans (GAGs) of adult skin versican are smaller in size and show differences in their sulfation pattern relative to those in fetal skin versican. In contrast to human skin versican, human skin decorin shows minimal age-related differences in its sulfation pattern, although, like versican, the GAGs of adult skin decorin are smaller than those of fetal skin decorin. Analysis of the catabolic fragments of decorin from adult skin reveals the presence of other fragments in addition to decorunt, although the core proteins of these additional decorin catabolic fragments have not been identified. Thus, versican and decorin of human skin show age-related differences, versican primarily in the size and the sulfation pattern of its GAGs and decorin in the size of its GAGs. The catabolic fragments of versican are detected at all ages examined, but appear to be in lower abundance in adult skin compared with fetal skin. In contrast, the catabolic fragments of decorin are present in adult skin, but are virtually absent from fetal skin. Taken together, these data suggest that there are age-related differences in the catabolism of proteoglycans in human skin. These age-related differences in proteoglycan patterns and catabolism may play a role in the age-related changes in the physical properties and injury response of human ski

Roles of Proteoglycans and Glycosaminoglycans in Wound Healing and Fibrosis

A wound is a type of injury that damages living tissues. In this review, we will be referring mainly to healing responses in the organs including skin and the lungs. Fibrosis is a process of dysregulated extracellular matrix (ECM) production that leads to a dense and functionally abnormal connective tissue compartment (dermis). In tissues such as the skin, the repair of the dermis after wounding requires not only the fibroblasts that produce the ECM molecules, but also the overlying epithelial layer (keratinocytes), the endothelial cells, and smooth muscle cells of the blood vessel and white blood cells such as neutrophils and macrophages, which together orchestrate the cytokine-mediated signaling and paracrine interactions that are required to regulate the proper extent and timing of the repair process. This review will focus on the importance of extracellular molecules in the microenvironment, primarily the proteoglycans and glycosaminoglycan hyaluronan, and their roles in wound healing. First, we will briefly summarize the physiological, cellular, and biochemical elements of wound healing, including the importance of cytokine cross-talk between cell types. Second, we will discuss the role of proteoglycans and hyaluronan in regulating these processes. Finally, approaches that utilize these concepts as potential therapies for fibrosis are discussed

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie