Inter-alpha-inhibitor, hyaluronan and inflammation.

Inter-alpha-inhibitor is an abundant plasma protein whose physiological function is only now beginning to be revealed. It consists of three polypeptides: two heavy chains and one light chain called bikunin. Bikunin, which has antiproteolytic activity, carries a chondroitin sulphate chain to which the heavy chains are covalently linked. The heavy chains can be transferred from inter-alpha-inhibitor to hyaluronan molecules and become covalently linked. This reaction seems to be mediated by TSG-6, a protein secreted by various cells upon stimulation by inflammatory cytokines. Inter-alpha-inhibitor has been shown to be required for the stabilization of the cumulus cell-oocyte complex during the expansion that occurs prior to ovulation. Hyaluronan-linked heavy chains in the extracellular matrix of this cellular complex have recently been shown to be tightly bound to TSG-6. Since TSG-6 binds to hyaluronan, its complex with heavy chains could stabilize the extracellular matrix by cross-linking hyaluronan molecules. Heavy chains linked to hyaluronan molecules have also been found in inflamed tissues. The physiological role of these complexes is not known but there are indications that they might protect hyaluronan against fragmentation by reactive oxygen species. TSG-6 also binds to bikunin thereby enhancing its antiplasmin activity. Taken together, these results suggest that inter-alpha-inhibitor is an anti-inflammatory agent which is activated by TSG-6.

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The extracellular matrix of the developing cornea: diversity, deposition and function*

Development ◽

10.1242/dev.103.supplement.195 ◽

1988 ◽

Vol 103 (Supplement) ◽

pp. 195-205

Author(s):

J. B. L. Bard ◽

M. K. Bansal ◽

A. S. A. Ross

Keyword(s):

Extracellular Matrix ◽

Chondroitin Sulphate ◽

Corneal Stroma ◽

Experimental System ◽

Collagen I ◽

And Function ◽

20 Nm

This paper examines the role of the extracellular matrix (ECM) in the development of the cornea. After a brief summary of the corneal structure and ECM, we describe evidence suggesting that the differentiation of neural crest (NC) cells into endothelium and fibroblasts is under the control of ocular ECM. We then examine the role of collagen I in stromal morphogenesis by comparing normal corneas with those of homozygous Movl3 mice which do not make collagen I. We report that, in spite of this absence, the cellular morphology of the Movl3 eye is indistinguishable from that of the wild type. In the 16-day mutant stroma, however, the remaining collagens form small amounts of disorganized, thin fibrils rather than orthogonally organized 20 nm-diameter fibrils; a result implying that collagen I plays only a structural role and that its absence is not compensated for. It also suggests that, because these remaining collagens will not form the normal fibrils that they will in vitro, fibrillogenesis in the corneal stroma differs from that elsewhere. The latter part of the paper describes our current work on chick stromal deposition using corneal epithelia isolated with an intact basal lamina that lay down in vitro ∼3μm-thick stromas of organized fibrils similar to that seen in vivo. This experimental system has yielded two unexpected results. First, the amount of collagen and proteoglycans produced by such epithelia is not dependent on whether its substratum is collagenous and we therefore conclude that stromal production by the intact epithelium is more autonomous than hitherto thought. Second, chondroitin sulphate (CS), the predominant proteoglycan, appears to play no role in stromal morphogenesis: epithelia cultured in testicular hyaluronidase, which degrades CS, lay down stromas whose organization and fibrildiameter distribution are indistinguishable from controls. One possible role for CS, however, is as a lubricant which facilitates corneal growth: it could allow fibrils to move over one another without deforming their orthogonal organization. Finally, we have examined the processes of fibrillogenesis in the corneal stroma and conclude that they are different from those elsewhere in the embryo and in vitro, perhaps because there is in the primary stroma an unidentified, highly hydrated ECM macromolecule that embeds the fibrils and that may mediate their morphogenesis.

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Visualizing endogenous opioid receptors in living neurons using ligand-directed chemistry

eLife ◽

10.7554/elife.49319 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 8

Author(s):

Seksiri Arttamangkul ◽

Andrew Plazek ◽

Emily J Platt ◽

Haihong Jin ◽

Thomas F Murray ◽

...

Keyword(s):

Opioid Receptors ◽

Physiological Role ◽

Loss Of Function ◽

Wild Type ◽

Endogenous Opioid ◽

Covalently Linked ◽

Living Tissues ◽

Living Neurons ◽

Post Hoc

Identifying neurons that have functional opioid receptors is fundamental for the understanding of the cellular, synaptic and systems actions of opioids. Current techniques are limited to post hoc analyses of fixed tissues. Here we developed a fluorescent probe, naltrexamine-acylimidazole (NAI), to label opioid receptors based on a chemical approach termed ‘traceless affinity labeling’. In this approach, a high affinity antagonist naltrexamine is used as the guide molecule for a transferring reaction of acylimidazole at the receptor. This reaction generates a fluorescent dye covalently linked to the receptor while naltrexamine is liberated and leaves the binding site. The labeling induced by this reagent allowed visualization of opioid-sensitive neurons in rat and mouse brains without loss of function of the fluorescently labeled receptors. The ability to locate endogenous receptors in living tissues will aid considerably in establishing the distribution and physiological role of opioid receptors in the CNS of wild type animals.

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Inhibition of cell adhesion to glycoproteins of the extracellular matrix by peptides corresponding to serum amyloid A. Toward understanding the physiological role of an enigmatic protein

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1994.tb18963.x ◽

1994 ◽

Vol 223 (1) ◽

pp. 35-42 ◽

Cited By ~ 48

Author(s):

Liana PRECIADO-PATT ◽

David LEVARTOWSKY ◽

Mordechai PRASS ◽

Rami HERSHKOVIZ ◽

Ofer LIDER ◽

...

Keyword(s):

Extracellular Matrix ◽

Cell Adhesion ◽

Serum Amyloid A ◽

Physiological Role ◽

Serum Amyloid ◽

Amyloid A

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The crosstalk of hyaluronan-based extracellular matrix and synapses

Neuron Glia Biology ◽

10.1017/s1740925x09990226 ◽

2008 ◽

Vol 4 (3) ◽

pp. 249-257 ◽

Cited By ~ 46

Author(s):

Renato Frischknecht ◽

Constanze I. Seidenbecher

Keyword(s):

Extracellular Matrix ◽

Nervous System ◽

Hyaluronic Acid ◽

Chondroitin Sulphate ◽

Specific Form ◽

Perineuronal Net ◽

Chondroitin Sulphate Proteoglycans ◽

And Function ◽

Brain Extracellular Space

Many neurons and their synapses are enwrapped in a brain-specific form of the extracellular matrix (ECM), the so-called perineuronal net (PNN). It forms late in the postnatal development around the time when synaptic contacts are stabilized. It is made of glycoproteins and proteoglycans of glial as well as neuronal origin. The major organizing polysaccharide of brain extracellular space is the polymeric carbohydrate hyaluronic acid (HA). It forms the backbone of a meshwork consisting of CNS proteoglycans such as the lectican family of chondroitin sulphate proteoglycans (CSPG). This family comprises four abundant components of brain ECM: aggrecan and versican as broadly expressed CSPGs and neurocan and brevican as nervous-system-specific family members. In this review, we intend to focus on the specific role of the HA-based ECM in synapse development and function.

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Under the ECM Dome: The Physiological Role of the Perinodal Extracellular Matrix as an Ion Diffusion Barrier

Advances in Experimental Medicine and Biology - Myelin ◽

10.1007/978-981-32-9636-7_8 ◽

2019 ◽

pp. 107-122

Author(s):

Yoko Bekku ◽

Toshitaka Oohashi

Keyword(s):

Extracellular Matrix ◽

Diffusion Barrier ◽

Physiological Role ◽

Ion Diffusion

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Extracellular matrix: the gatekeeper of tumor angiogenesis

Biochemical Society Transactions ◽

10.1042/bst20190653 ◽

2019 ◽

Vol 47 (5) ◽

pp. 1543-1555 ◽

Cited By ~ 10

Author(s):

Maurizio Mongiat ◽

Simone Buraschi ◽

Eva Andreuzzi ◽

Thomas Neill ◽

Renato V. Iozzo

Keyword(s):

Extracellular Matrix ◽

Tumor Angiogenesis ◽

Signaling Cascades ◽

Cancer Growth ◽

Cell Behavior ◽

Metastatic Progression ◽

Surface Receptors ◽

The Matrix ◽

Multiple Signaling

Abstract The extracellular matrix is a network of secreted macromolecules that provides a harmonious meshwork for the growth and homeostatic development of organisms. It conveys multiple signaling cascades affecting specific surface receptors that impact cell behavior. During cancer growth, this bioactive meshwork is remodeled and enriched in newly formed blood vessels, which provide nutrients and oxygen to the growing tumor cells. Remodeling of the tumor microenvironment leads to the formation of bioactive fragments that may have a distinct function from their parent molecules, and the balance among these factors directly influence cell viability and metastatic progression. Indeed, the matrix acts as a gatekeeper by regulating the access of cancer cells to nutrients. Here, we will critically evaluate the role of selected matrix constituents in regulating tumor angiogenesis and provide up-to-date information concerning their primary mechanisms of action.

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