Tissue transglutaminase clusters soluble A-type ephrins into functionally active high molecular weight oligomers

Alford, Spencer C.; Bazowski, Jessa; Lorimer, Heather E.; Elowe, Sabine; Howard, Perry L.

doi:10.1016/j.yexcr.2007.07.019

Cited by 26 publications

(23 citation statements)

References 31 publications

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“…Whereas ephrin-A1 principally exists as a membrane-anchored protein, soluble forms (both monomeric and multimeric) have also been described (18)(19)(20). Our results suggest that such forms of ephrin-A1 are released into the alveolar space in the setting of lung injury.…”

Section: Discussionmentioning

confidence: 59%

Eph-A2 Promotes Permeability and Inflammatory Responses to Bleomycin-Induced Lung Injury

Carpenter

Schroeder²,

Stenmark³

et al. 2012

Am J Respir Cell Mol Biol

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Stimulation by the ephrin-A1 ligand of the EphA2 receptor increases endothelial permeability. Lung injury increases the expression of EphA2, but the role of EphA2 in such injury is not well understood. To determine whether EphA2 contributes to changes in permeability and inflammation in the injured lung, we studied wild-type (WT) and EphA2 knockout (KO) mice, using isolated, perfused lung (IPL) preparations and a model of bleomycin-induced lung injury. We also studied the response of endothelial cells to ephrin-A1. In the IPL preparations, ephrin-A1 increased the filtration coefficient in WT mice, but not in EphA2 KO mice, demonstrating that EphA2 regulates vascular permeability. In early bleomycin injury in WT mice, the expression of both EphA2 and ephrin-A1 increased. EphA2 KO animals were protected from lung injury, showing less water and alveolar protein in the lungs than WT mice, consistent with reduced permeability. Bleomycin caused less accumulation of lung leukocytes in EphA2 KO animals than in WT animals, suggesting that EphA2 regulates inflammation. To determine whether EphA2 deficiency alters the production of chemokines, CXCL1 and CCL2 in the lungs were measured. After bleomycin injury, EphA2 KO animals produced less CXCL1 and CCL2 than WT animals. Because NF-kb mediates the production of chemokines, the effect of the ephrin-A1 ligand on the activation of NF-kb and the expression of chemokines was measured in endothelial cells. Ephrin-a1 significantly increased NFkb nuclear translocation and the expression of chemokine mRNA. This study demonstrates that the expression of EphA2 increases in the injured lung, and not only contributes to changes in permeability, but also plays a previously unrecognized role in promoting inflammatory responses.Keywords: chemokine; ephrin-A1; inflammation; vascular leakThe ephrins are a large family of receptor tyrosine kinases and ligands with demonstrated importance in both neural and vascular development. Ephrin ligands and Eph receptors are both cellsurface molecules, and as such, are primarily described to mediate cell-cell interactions, leading to either repulsive or attractive cell contacts and the regulation of behaviors such as axonal pathfinding in the central nervous system. Although less is known about the role of ephrins in the vasculature, some members of the family have been implicated in postnatal angiogenesis. In particular, the EphA2 receptor and its cognate ligand ephrin-A1 were shown to contribute to migration and tube formation in lung endothelial cells (1-3).Responses that promote cell migration and repulsive cell contacts are generally associated with a loss of cell-cell junctions, and might be expected to increase vascular permeability. We previously demonstrated that stimulation by the ephrin-A1 ligand leads both in vitro and in vivo to increases in lung endothelial permeability (4). These effects are associated with evidence of a breakdown of both adherens and tight junctions in endothelial cells. In addition, we recently presented data demonstra...

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Section: Discussionmentioning

confidence: 59%

Eph-A2 Promotes Permeability and Inflammatory Responses to Bleomycin-Induced Lung Injury

Carpenter

Schroeder²,

Stenmark³

et al. 2012

Am J Respir Cell Mol Biol

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“…This requirement was thought to be due to the necessity of Eph receptors themselves to undergo clustering in order to be activated (16,24,61). Until recently, while there has been evidence put forth demonstrating the existence of soluble ephrins (3,22,65), there has been sparse evidence for functionality of a soluble, monomeric form of any member of the ephrinA family. In fact, soluble, unclustered ephrinA5 stimulated autophosphorylation of EphA5 only weakly, and it was proposed that soluble ephrinA5 is actually an antagonist of axon bundling (65).…”

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confidence: 99%

“…Furthermore, ephrinA1 and ephrinA5 exist in soluble forms and are substrates for clustering by tissue transglutaminase (3). This clustering was considered necessary for formation of functional soluble forms of ephrinA family members.…”

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confidence: 99%

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EphrinA1 Is Released in Three Forms from Cancer Cells by Matrix Metalloproteases

Beauchamp

Lively

Mintz

et al. 2012

Molecular and Cellular Biology

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EphrinA1 is a glycosylphosphatidylinositol (GPI)-linked ligand for the EphA2 receptor, which is overexpressed in glioblastoma (GBM), among other cancers. Activation of the receptor by ephrinA1 leads to a suppression of oncogenic properties of GBM cells. We documented that a monomeric functional form of ephrinA1 is released from cancer cells and thus explored the mechanism of ephrinA1 release and the primary protein sequence. We demonstrate here that multiple metalloproteases (MMPs) are able to cleave ephrinA1, most notably MMP-1, -2, -9, and -13. The proteolytic cleavage that releases ephrinA1 occurs at three positions near the C terminus, producing three forms ending in valine-175, histidine-177, or serine-178. Moreover, deletion of amino acids 174 to 181 or 175 to 181 yields ephrinA1 that is still GPI linked but not released by proteolysis, underlining the necessity of amino acids 175 to 181 for release from the membrane. Furthermore, recombinant ephrinA1 ending at residue 175 retains activity toward the EphA2 receptor. These findings suggest a mechanism of release and provide evidence for the existence of several forms of monomeric ephrinA1. Moreover, ephrinA1 should be truncated at a minimum at amino acid 175 in fusions or conjugates with other molecules in order to prevent likely proteolysis within physiological and pathobiological environments.

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“…Interestingly, A-type ephrins are also cleaved by ADAM family metalloproteases (32). Although regulated ephrin-A cleavage upon EphA receptor binding has recently attracted much attention, other studies have demonstrated constitutive release of A-type ephrins from cells (33)(34)(35) and suggest possible long-range activities of released A-type ephrins (36). Although the physiological significance of these shedding events remains to be determined, these observations suggest the possibility that heparan sulfate serves to capture released ephrin-A3 on the cell surface.…”

Section: Discussionmentioning

confidence: 99%

Heparan sulfate regulates ephrin-A3/EphA receptor signaling

Irie¹,

Okuno²,

Matsumoto³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Increasing evidence indicates that many signaling pathways involve not only ligands and receptors but also various types of coreceptors and matrix components as additional layers of regulation. Signaling by Eph receptors and their ephrin ligands plays a key role in a variety of biological processes, such as axon guidance and topographic map formation, synaptic plasticity, angiogenesis, and cancer. Little is known about whether the ephrin-Eph receptor signaling system is subject to such additional layers of regulation. Here, we show that ephrin-A3 binds to heparan sulfate, and that the presence of cell surface heparan sulfate is required for the full biological activity of ephrin-A3. Among the ephrins tested, including ephrin-A1, -A2, -A5, -B1, and -B2, only ephrin-A3 binds heparin or heparan sulfate. Ephrin-A3-dependent EphA receptor activation is reduced in mutant cells that are defective in heparan sulfate synthesis, in wild-type cells from which cell surface heparan sulfate has been removed, and in the hippocampus of conditional knockout mice defective in heparan sulfate synthesis. Ephrin-A3-dependent cell rounding is impaired in CHO cells lacking heparan sulfate, and cortical neurons lacking heparan sulfate exhibit impaired growth cone collapse. In contrast, cell rounding and growth cone collapse in response to ephrin-A5, which does not bind heparan sulfate, are not affected by the absence of heparan sulfate. These results show that heparan sulfate modulates ephrin/Eph signaling and suggest a physiological role for heparan sulfate proteoglycans in the regulation of ephrin-A3-dependent biological processes.proteoglycan ͉ cell adhesion ͉ growth cone collapse H eparan sulfate is a class of sulfated glycosaminoglycans. It occurs as heparan sulfate proteoglycans, in which one or more heparan sulfate chains are covalently attached to a variety of core proteins (1). Heparin is a specialized form of heparan sulfate synthesized exclusively by connective tissue mast cells, whereas heparan sulfate is expressed in many cell types. The negatively charged sulfate groups of heparan sulfate mediate interactions with a variety of proteins. Increasing evidence indicates that heparan sulfate acts as an integral component of a number of morphogen and growth factor signaling pathways by interacting with these molecules. For example, fibroblast growth factors, Wnts, Sonic hedgehog, bone morphogenetic proteins, and neuregulins bind to heparan sulfate and are functionally modulated by it (2, 3). Molecules involved in axon pathfinding, such as netrin-1, Slit, and semaphorins, are other major targets of regulation by heparan sulfate (4). We have used genetic ablation of the Ext1 gene, which encodes a glycosyltransferase essential for heparan sulfate synthesis (5, 6), to demonstrate the physiological significance of the interactions of some of these molecules with heparan sulfate (7-9).The Eph receptors form the largest family of receptor tyrosine kinases. Together with their membrane-bound ligands, the ephrins, they are involved in b...

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Tissue transglutaminase clusters soluble A-type ephrins into functionally active high molecular weight oligomers

Cited by 26 publications

References 31 publications

Eph-A2 Promotes Permeability and Inflammatory Responses to Bleomycin-Induced Lung Injury

Eph-A2 Promotes Permeability and Inflammatory Responses to Bleomycin-Induced Lung Injury

EphrinA1 Is Released in Three Forms from Cancer Cells by Matrix Metalloproteases

Heparan sulfate regulates ephrin-A3/EphA receptor signaling

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