Heparanase deglycanation of syndecan-1 is required for binding of the epithelial-restricted prosecretory mitogen lacritin

Ma, Peisong; Beck, Shannon; Raab, Ronald W.; McKown, Robert L.; Coffman, George L.; Chirico, William J.; Rapraeger, Alan C.; Laurie, Gordon W.

doi:10.1083/jcb.20051113420110107c

Cited by 17 publications

(39 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…HSPGs have been shown to play important roles in cell adhesion, migration and tumorigenesis [82][83][84][85]. Syndecans play important roles in growth factor presentation and receptor activation [86], matrix adhesion [87], cell-cell adhesion [88], and tumour suppression [89] and progression [90,91].…”

Section: Cancermentioning

confidence: 99%

The glycocalyx and its significance in human medicine

2016

View full text Add to dashboard Cite

Cells are covered by a surface layer of glycans that is referred to as the 'glycocalyx'. In this review, we focus on the role of the glycocalyx in vascular diseases (atherosclerosis, stroke, hypertension, kidney disease and sepsis) and cancer. The glycocalyx and its principal glycosaminoglycans [heparan sulphate (HS) and hyaluronic acid (HA)] and core proteins (syndecans and glypicans) are degraded in vascular diseases, leading to a breakdown of the vascular permeability barrier, enhanced access of leucocytes to the arterial intima that propagate inflammation and alteration of endothelial mechanotransduction mechanisms that protect against disease. By contrast, the glycocalyx on cancer cells is generally robust, promoting integrin clustering and growth factor signalling, and mechanotransduction of interstitial flow shear stress that is elevated in tumours to upregulate matrix metalloproteinase release which enhances cell motility and metastasis. HS and HA are consistently elevated on cancer cells and are associated with tumour growth and metastasis. Later, we will review the agents that might be used to enhance or protect the glycocalyx to combat vascular disease, as well as a different set of compounds that can degrade the cancer cell glycocalyx to suppress cell growth and metastasis. It is clear that what is beneficial for either vascular disease or cancer will not be so for the other. The overarching conclusions are that (i) the importance of the glycocalyx in human medicine is only beginning to be recognized, and (ii) more detailed studies of glycocalyx involvement in vascular diseases and cancer will lead to novel treatment modalities.

show abstract

Section: Cancermentioning

confidence: 99%

The glycocalyx and its significance in human medicine

2016

View full text Add to dashboard Cite

show abstract

“…Bioactivity of Tgm2 modified lacritin was assessed via syndecan-1 affinity precipitation. 21 For affinity precipitation, lacritin-intein on chitin beads was either left untreated, or alternatively was incubated for 40 minutes with 1.5 lM Tgm2, 1.5 lM inactive recombinant TGM2, or 1.5 lM boiled Tgm2. Negative control C-25-intein truncation mutant 21 (incapable of binding syndecan-1) was similarly bacterialexpressed and linked to chitin.…”

Section: Tgm2 Modification Of Lacritin and Inhibition Studiesmentioning

confidence: 99%

“…Some has been detected in the thyroid gland, 15 lactating breast (McKown RL, et al IOVS 2012;53:ARVO E-Abstract 4235), and in lung lavage. 20 Lacritin targets cell surface syndecan-1, 21 which is extensively expressed on ocular surface epithelia, 22 and requires heparanase to expose 21 and in part create 40 the lacritin binding site within its N-terminus. Heparanase is normally expressed by the corneal epithelium.…”

mentioning

confidence: 99%

Tissue Transglutaminase Is a Negative Regulator of Monomeric Lacritin Bioactivity

Velez

Romano

McKown

et al. 2013

Invest. Ophthalmol. Vis. Sci.

Self Cite

View full text Add to dashboard Cite

PURPOSE. Molar accounting of bioactive fluids can expose new regulatory mechanisms in the growing proteomic focus on epithelial biology. Essential for the viability of the surface epithelium of the eye and for normal vision is the thin, but protein-rich, tear film in which the small tear glycoprotein lacritin appears to play a prominent prosecretory, cytoprotective, and mitogenic role. Although optimal bioactive levels in cell culture are 1 to 10 nM over a biphasic dose optimum, ELISA suggests a sustained tear lacritin concentration in the midmicromolar range in healthy adults. Here we identify a reconciling mechanism.METHODS. Monoclonal anti-lacritin 1F5 antibody was generated, and applied together with a new anti-C-terminal polyclonal antibody to tear and tissue Western blotting. In vitro tissue transglutaminase (Tgm2) cross-linking was monitored and characterized by mass spectrometry.RESULTS. Blotting for lacritin in human tears or saliva surprisingly detected immunoreactive material with a higher molecular weight and prominence equal or exceeding the~23 to 25 kDa band of monomeric glycosylated lacritin. Exogenous Tgm2 initiated lacritin cross-linking within 1 minute and was complete by 90 minutes-even with as little as 0.1 nM lacritin, and involved the donors lysine 82 and 85 and the acceptor glutamine 106 in the syndecan-1 binding domain. Lacritin spiked into lacritin-depleted tears formed multimers, in keeping with~0.6 lM TGM2 in tears. Cross-linking was absent when Tgm2 was inactive, and cross-linked lacritin, unlike recombinant monomer, bound syndecan-1 poorly. Enhanced TGM2 expression correlates with reduced cell viability, caspase activation, TNF receptor clustering, 7 and mitochondrial dysfunction 8 associated with hyperosmolar stress in dry eye. 9 Transglutaminases encompass a multifunctional family of enzymes involved in high-fidelity posttranslational modifications that catalyze Ca 2þ -dependent covalent bond formation between primary amines or e-amino groups of lysine and c-carboxamide groups of glutamine. Cross-linking affects function, both negatively and positively. TGM2 crosslinked collagen is resistant to metalloproteinase digestion and less mitogenic 10 ; and cross-linked IL-2 (unlike IL-2 monomer) is cytotoxic for oligodendrocytes. 11 TGM2 also positively regulates the activity of midkine, a small heparin binding growth factor, 12 and is required for the activation of latent TGF-b 13 and S100A11.14 Could TGM2 in tears regulate ocular surface biology?Lacritin is a 12.3 kDa tear prosecretory mitogen 15 with glutamine and lysine residues suitable for TGM2 catalyzed cross-linking. Lacritin promotes corneal epithelial cell survival (Zimmerman K, et al. IOVS 2012;53:ARVO E-Abstract 4231) and proliferation, 16 and basal tear protein secretion by lacrimal acinar cells. 15 When topically applied to rabbit eyes, lacritin acutely increases basal tear flow. 17 Lacritin is largely restricted to tears and to a lesser extent saliva, through its lacrimal acinar cell, 15

show abstract

“…Indeed, lacritin promoted protein secretion from cultured rat acinar cells 16 and stimulated proliferation in cultured human corneal cells and salivary ductal cells. 17,18 Furthermore, in vivo instillation of recombinant human lacritin stimulated basal tear flow in rabbits. 19 However, no data are available on lacritin-induced secretion of tear proteins in the more relevant monkey model.…”

mentioning

confidence: 99%

Lacritin-Induced Secretion of Tear Proteins From Cultured Monkey Lacrimal Acinar Cells

Fujii

Morimoto-Tochigi

Walkup

et al. 2013

Invest. Ophthalmol. Vis. Sci.

View full text Add to dashboard Cite

PURPOSE. During inflammation of the ocular surface, increased proinflammatory cytokines depress tear protein secretion, suggesting that a decline in lacrimal cell function contributes to dry eye. Lacritin, a glycoprotein secreted from lacrimal acinar cells, may function as an autocrine factor to stimulate tear protein secretion. The purpose of the present experiment was to investigate lacritin-induced protein secretion in normal and cytokine-pretreated (inflammation model) monkey acinar cells.METHODS. Acinar cells from monkey lacrimal glands were cultured with or without tumor necrosis factor alpha (TNF-a) plus interferon gamma (IFN-c). Protein secretion was induced by lacritin or carbachol (Cch, positive control). Proteins were detected and identified by immunoblotting and immunocytochemistry. Intracellular Ca 2þ was measured with the fluorophore Calcium-4, and cell damage was determined by LDH leakage into the culture medium. RESULTS. In cultured monkey acinar cells, lacritin stimulated tear protein secretion in normal cells without elevating intracellular Ca 2þ. In contrast, Cch elevated intracellular Ca 2þ and release of tear proteins. This contrast suggested an alternate, calcium-independent mechanism for lacritin-induced protein secretion. TNF-a plus IFN-c caused LDH leakage from sensitive human corneal epithelial cells, but even higher doses of TNF-a plus IFN-c did not cause LDH leakage from monkey acinar cells, suggesting a higher tolerance against these cytokines. In cytokine-treated acinar cells, lacritin stimulated protein secretion as much as that in normal cells. In contrast, Cch-induced elevation of Ca 2þ and release of proteins were depressed by cytokines.CONCLUSIONS. Lacritin might be a useful biotechnology-based treatment agent against ocular surface diseases where endogenous lacritin is inadequate.

show abstract

Heparanase deglycanation of syndecan-1 is required for binding of the epithelial-restricted prosecretory mitogen lacritin

Cited by 17 publications

References 0 publications

The glycocalyx and its significance in human medicine

The glycocalyx and its significance in human medicine

Tissue Transglutaminase Is a Negative Regulator of Monomeric Lacritin Bioactivity

Lacritin-Induced Secretion of Tear Proteins From Cultured Monkey Lacrimal Acinar Cells

Contact Info

Product

Resources

About