N-deacetylase/N-sulfotransferase-1 Research Articles

Dissection of N-deacetylase and N-sulfotransferase activities of NDST1 and their effects on Wnt8 distribution and signaling in Xenopus embryos.

Wnt is a family of secreted signaling proteins involved in the regulation of cellular processes, including maintenance of stem cells, carcinogenesis, and cell differentiation. In the context of early vertebrate embryogenesis, graded distribution of Wnt proteins has been thought to regulate positional information along the antero-posterior axis. However, understanding of the molecular basis for Wnt spatial distribution remains poor. Modified states of heparan sulfate (HS) proteoglycans are essential for Wnt8 localization, because depletion of N-deacetylase/N-sulfotransferase 1 (NDST1), a modification enzyme of HS chains, decreases Wnt8 levels and NDST1 overexpression increases Wnt8 levels on the cell surface. Since overexpression of NDST1 increases both deacetylation and N-sulfation of HS chains, it is not clear which function of NDST1 is actually involved in Wnt8 localization. In the present study, we generated an NDST1 mutant that specifically increases deacetylation, but not N-sulfation, of HS chains in Xenopus embryos. Unlike wild-type NDST1, this mutant did not increase Wnt8 accumulation on the cell surface, but it reduced canonical Wnt signaling, as determined with the TOP-Flash reporter assay. These results suggest that N-sulfation of HS chains is responsible for localization of Wnt8 and Wnt8 signaling, whereas deacetylation has an inhibitory effect on canonical Wnt signaling. Consistently, overexpression of wild-type NDST1, but not the mutant, resulted in small eyes in Xenopus embryos. Thus, our NDST1 mutant enables us to dissect the regulation of Wnt8 localization and signaling by HS proteoglycans by specifically manipulating the enzymatic activities of NDST1.

The role and mechanism of NDST1/NULP1 regulating right ventricular hypertrophy in hypoxic pulmonary hypertension.

Hypoxia leads to hypoxic pulmonary hypertension (HPH), causing right ventricular hypertrophy (RVH). RVH becomes a significant and nonnegligible public health issue in the world. In our study, we successfully established the HPH rat model and found that RVH happened in HPH, and then we observed an increased inflammation response in the heart tissue of HPH-induced RVH rats. Moreover, increased N-deacetylase-N-sulfotransferase-1 (NDST1) and decreased nuclear localized protein 1 (NULP1) were found in the heart tissue of HPH-induced RVH rats. An in vitro cell experiment showed that inhibition of NDST1 expression enhanced cell viability, reduced cell apoptosis, alleviated cardiomyocyte hypertrophy, decreased inflammation and increased phosphorylated AKT level, however, over-expression of NDST1 had opposite effects on these aspects. NULP1 reversed the effects of NDST1 on these regulations. Finally, we found that up-regulated NDST1 reduced NULP1 expression and down-regulated NDST1 increased NULP1 expression. Our study confirmed that inhibition of the NDST1/NULP1 pathway might contribute to the attenuation of HPH-induced RVH, and the mechanism may be related to the reduction of inflammation, cardiomyocyte apoptosis, and AKT phosphorylation.

The construction of a dual-functional strain that produces both polysaccharides and sulfotransferases.

Heparosan is used as the starting polysaccharide sulfated using sulfotransferase to generate fully elaborate heparin, a widely used clinical drug. However, the preparation of heparosan and enzymes was considered tedious since such material must be prepared in separate fermentation batches. In this study, a commonly admitted probiotic, Escherichia coli strain Nissle 1917 (EcN), was engineered to intracellularly express sulfotransferases and, simultaneously, secreting heparosan into the culture medium. The engineered strain EcN::T7M, carrying the λDE3 region of BL21(DE3) encoding T7 RNA polymerase, expressed the sulfotransferase domain (NST) of human N-deacetylase/N-sulfotransferase-1 (NDST-1) and the catalytic domain of mouse 3-O-sulfotransferase-1 (3-OST-1) in a flask. The fed-batch fermentation of EcN::T7M carrying the plasmid expressing NST was carried out, which brought the yield of NST to 0.21g/L and the yield of heparosan to 0.85g/L, respectively. Furthermore, the heparosan was purified, characterized by 1H nuclear magnetic resonance (NMR), and sulfated by NST using 3'-phosphoadenosine-5'-phosphosulfate (PAPS) as the sulfo donor. The analysis of element composition showed that over 80% of disaccharide repeats of heparosan were N-sulfated. These results indicate that EcN::T7M is capable of preparing sulfotransferase and heparosan at the same time. The EcN::T7M strain is also a suitable host for expressing exogenous proteins driven by tac promoter and T7 promoter.

MiRNA-191 functions as an oncogene in primary glioblastoma by directly targeting NDST1.

Glioblastoma is identified as the most aggressive primary brain tumor. Growing evidence has demonstrated that aberrant expression of miR-191 has oncogenic potentiality in many cancers. However, the effects and the underlying mechanisms of miR-191 in the development of glioblastoma remain largely unknown. The aim of this study was to elucidate the pathobiological functions of miR-191 expression by targeting N-deacetylase/N-sulfotransferase 1 (NDST1) in human glioblastoma. The miR-191 level in human glioblastoma tissues and four cell lines was examined using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Animals study and MTT (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay were used to examine the effects of miR-191 on human glioblastoma proliferation. Western blot and Luciferase reporter were used to confirm that miR-191 could regulate NDST1 expression. We found that the miR-191 expression was upregulated in human glioblastoma tissues and cells. MiR-191 over-expression was sufficient to promote human glioblastoma cells growth in vivo and in vitro. We also found that miR-191 directly targeted NDST1 and negatively regulated the NDST1 expression in human glioblastoma cells. In summary, our finding suggested that miR-191 acted as an important regulator in promoting glioblastoma cell proliferation in vivo and in vitro, and this cellular function may be because of its negative regulation of NDST1.

N-sulfation of heparan sulfate is critical for syndecan-4-mediated podocyte cell-matrix interactions.

Previous research has shown that podocytes unable to assemble heparan sulfate on cell surface proteoglycan core proteins have compromised cell-matrix interactions. This report further explores the role of N-sulfation of intact heparan chains in podocyte-matrix interactions. For the purposes of this study, a murine model in which the enzyme N-deacetylase/N-sulfotransferase 1 (NDST1) was specifically deleted in podocytes and immortalized podocyte cell lines lacking NDST1 were developed and used to explore the effects of such a mutation on podocyte behavior in vitro. NDST1 is a bifunctional enzyme, ultimately responsible for N-sulfation of heparan glycosaminoglycans produced by cells. Immunostaining of glomeruli from mice whose podocytes were null for Ndst1 (Ndst1(-/-)) showed a disrupted pattern of localization for the cell surface proteoglycan, syndecan-4, and for α-actinin-4 compared with controls. The pattern of immunostaining for synaptopodin and nephrin did not show as significant alterations. In vitro studies showed that Ndst1(-/-) podocytes attached, spread, and migrated less efficiently than Ndst1(+/+) podocytes. Immunostaining in vitro for several markers for molecules involved in cell-matrix interactions showed that Ndst1(-/-) cells had decreased clustering of syndecan-4 and decreased recruitment of protein kinase-Cα, α-actinin-4, vinculin, and phospho-focal adhesion kinase to focal adhesions. Total intracellular phospho-focal adhesion kinase was decreased in Ndst1(-/-) compared with Ndst1(+/+) cells. A significant decrease in the abundance of activated integrin α5β1 on the cell surface of Ndst1(-/-) cells compared with Ndst1(+/+) cells was observed. These results serve to highlight the critical role of heparan sulfate N-sulfation in facilitating normal podocyte-matrix interactions.

Methylation-regulated miR-149 modulates chemoresistance by targeting GlcNAc N-deacetylase/N-sulfotransferase-1 in human breast cancer.

Dysregulation of microRNA is strongly implicated in the chemoresistance of cancer. In this study, we found that miR-149 was downregulated and involved in chemoresistance in adriamycin (ADM)-resistant human breast cancer cells (MCF-7/ADM). Downregulation of miR-149 was related to hypermethylation of its 5'-UTR; this methylation also affected the expression of the glypican 1 gene, which is both the host and the target gene of miR-149. Furthermore, we found that miR-149 modulated chemoresistance through targeting the expression of GlcNAc N-deacetylase/N-sulfotransferase-1 (NDST1). With downregulated miR-149, NDST1 expression was increased in chemoresistant MCF-7/ADM cells versus control MCF-7 wild-type cells. The increased NDST1 then activated a heparan sulfate-related pathway involving activation of heparanase. Finally, expression of miR-149 and NDST1 was confirmed in clinical chemoresistant samples of breast cancers receiving anthracycline/taxane-based chemotherapies. The high expression of NDST1 was also an unfavorable predictor for distant relapse-free survival in Her2 and basal breast cancers. Taken together, our findings demonstrate that miR-149 is regulated by methylation, and is a modulator of cancer chemoresistance by targeting NDST1.

Heparan Sulfate Containing Unsubstituted Glucosamine Residues: BIOSYNTHESIS AND HEPARANASE-INHIBITORY ACTIVITY

Degradation of heparan sulfate (HS) in the extracellular matrix by heparanase is linked to the processes of tumor invasion and metastasis. Thus, a heparanase inhibitor can be a potential anticancer drug. Because HS with unsubstituted glucosamine residues accumulates in heparanase-expressing breast cancer cells, we assumed that these HS structures are resistant to heparanase and can therefore be utilized as a heparanase inhibitor. As expected, chemically synthetic HS-tetrasaccharides containing unsubstituted glucosamine residues, GlcAβ1-4GlcNH3 (+)(6-O-sulfate)α1-4GlcAβ1-4GlcNH3 (+)(6-O-sulfate), inhibited heparanase activity and suppressed invasion of breast cancer cells in vitro. Bifunctional NDST-1 (N-deacetylase/N-sulfotransferase-1) catalyzes the modification of N-acetylglucosamine residues within HS chains, and the balance of N-deacetylase and N-sulfotransferase activities of NDST-1 is thought to be a determinant of the generation of unsubstituted glucosamine. We also report here that EXTL3 (exostosin-like 3) controls N-sulfotransferase activity of NDST-1 by forming a complex with NDST-1 and contributes to generation of unsubstituted glucosamine residues.

MicroRNA-24 Suppression of N-Deacetylase/N-Sulfotransferase-1 (NDST1) Reduces Endothelial Cell Responsiveness to Vascular Endothelial Growth Factor A (VEGFA)

Heparan sulfate (HS) proteoglycans, present at the plasma membrane of vascular endothelial cells, bind to the angiogenic growth factor VEGFA to modulate its signaling through VEGFR2. The interactions between VEGFA and proteoglycan co-receptors require sulfated domains in the HS chains. To date, it is essentially unknown how the formation of sulfated protein-binding domains in HS can be regulated by microRNAs. In the present study, we show that microRNA-24 (miR-24) targets NDST1 to reduce HS sulfation and thereby the binding affinity of HS for VEGFA. Elevated levels of miR-24 also resulted in reduced levels of VEGFR2 and blunted VEGFA signaling. Similarly, suppression of NDST1 using siRNA led to a reduction in VEGFR2 expression. Consequently, not only VEGFA binding, but also VEGFR2 protein expression is dependent on NDST1 function. Furthermore, overexpression of miR-24, or siRNA-mediated reduction of NDST1, reduced endothelial cell chemotaxis in response to VEGFA. These findings establish NDST1 as a target of miR-24 and demonstrate how such NDST1 suppression in endothelial cells results in reduced responsiveness to VEGFA.

N‐sulfation of Cell Surface Heparan Sulfate Glycosaminoglycans is Critical for Podocyte‐Matrix Interactions

Podocytes adhere to the glomerular basement membrane via cell surface receptors which include heparan sulfate (HS) proteoglycans (PG). Podocytes unable to assemble HS glycosaminoglycan chains have defective cell attachment and spreading, and cytoskeletal disruption in vitro and in vivo. The current report explores the importance of heparan sulfation in regulating podocyte cell‐matrix interactions, using an immortalized podocyte cell line having the genomic deletion of N‐deacetylase/ N‐sulfotransferase 1 (NDST1), the enzyme responsible for N‐sulfation of HS. Compared to wild type podocytes, mutant podocytes attached, spread and migrated less efficiently in assays than control cells. In the process of cell‐matrix interaction, the mutant cells showed decreased clustering of syndecan 4, the cell surface HSPG involved in focal adhesion formation, and decreased recruitment of PKCα, α‐actinin 4, vinculin, and pFAK to focal adhesions. Cell surface integrin expression and integrin activation/signaling was significantly diminished in the mutant cells. These results serve to highlight the critical role of HS N‐sulfation in regulating the ability of podocytes to interact with the extracellular matrix.Grant Funding Source: NIDDK RO1‐DK07786

Lowered Expression of Heparan Sulfate/Heparin Biosynthesis Enzyme N-Deacetylase/N-Sulfotransferase 1 Results in Increased Sulfation of Mast Cell Heparin

Deficiency of the heparan sulfate biosynthesis enzyme N-deacetylase/N-sulfotransferase 1 (NDST1) in mice causes severely disturbed heparan sulfate biosynthesis in all organs, whereas lack of NDST2 only affects heparin biosynthesis in mast cells (MCs). To investigate the individual and combined roles of NDST1 and NDST2 during MC development, in vitro differentiated MCs derived from mouse embryos and embryonic stem cells, respectively, have been studied. Whereas MC development will not occur in the absence of both NDST1 and NDST2, lack of NDST2 alone results in the generation of defective MCs. Surprisingly, the relative amount of heparin produced in NDST1(+/-) and NDST1(-/-) MCs is higher (≈30%) than in control MCs where ≈95% of the (35)S-labeled glycosaminoglycans produced is chondroitin sulfate. Lowered expression of NDST1 also results in a higher sulfate content of the heparin synthesized and is accompanied by increased levels of stored MC proteases. A model of the GAGosome, a hypothetical Golgi enzyme complex, is used to explain the results.

Epac1 promotes melanoma metastasis via modification of heparan sulfate

Our previous report suggested the potential role of the exchange protein directly activated by cyclic AMP (Epac) in melanoma metastasis via heparan sulfate (HS)-mediated cell migration. In order to obtain conclusive evidence that Epac1 plays a critical role in modification of HS and melanoma metastasis, we extensively investigated expression and function of Epac1 in human melanoma samples and cell lines. We have found that, in human melanoma tissue microarray, protein expression of Epac1 was higher in metastatic melanoma than in primary melanoma. In addition, expression of Epac1 positively correlated with that of N-sulfated HS, and N-deacetylase/N-sulfotransferase-1 (NDST-1), an enzyme that increases N-sulfation of HS. Further, an Epac agonist increased, but ablation of Epac1 decreased, expressions of NDST-1, N-sulfated HS, and cell migration in various melanoma cell lines. Finally, C8161 cells with stable knockdown of Epac1 showed a decrease in cell migration, and metastasis in mice. These data suggest that Epac1 plays a critical role in melanoma metastasis presumably because of modification of HS.

Abstract 3664: Epac1 activates migration of melanoma and angiogenesis of endothelial cells via FGF-2 intercellular signaling

Abstract Background: Fibroblast growth factor (FGF-2) regulates migration and angiogenesis in cancer. The binding of FGF-2 to its receptor requires N-sulfated glucosamine in heparan sulfate (HS), suggesting that a molecule that increases N-sulfation of glucosamine could enhance FGF-2 signaling. Recently, we demonstrated that Epac1, an exchange protein activated by cAMP, increases expression of N-deacetylase/N-sulfotransferase-1 (NDST-1) that increases N-sulfation of glucosamine. It is plausible that melanoma cells with abundant expression of Epac1 produce N-sulfation-rich glucosamine, which results in enhancement of intercellular FGF-2 signaling in melanoma microenvironment. The purpose of this study was to examine whether Epac1-rich melanoma cells can increase migration of surrounding Epac1-poor melanoma cells and endothelial cells. Methods: Immunohistochemistry was performed on human melanoma tissue microarrays to examine expressions of Epac1, NDST-1 and N-sulfated glucosamine. For in vitro studies, we used 2 human melanoma cell lines, WM1552C (radial growth phase melanoma) and C8161 (metastatic melanoma), and human umbilical vein endothelial cells (HUVEC). Since Epac1 expression was much lower in WM1552C than C8161 cells, WM1552C were used as Epac1-poor, and C8161 as Epac1-rich melanoma cells. We evaluated the migratory responses in WM1552C and HUVEC cells to conditioned medium (CM) from C8161 cells with or without Epac1 ablation (C8161/Epac1(−)) or overexpression (C8161/Epac1OE). Endothelial tube formation assay was performed in HUVEC with conditioned media. Results: The expression of Epac1 positively correlated with that of NDST-1, and N-sulfated glucosamine in human melanoma tissue microarray. Migration of WM1552C and HUVEC cells was increased by CM from C8161 cells, which was significantly enhanced by CM from C8161/Epac1OE, but reduced by CM from C8161/Epac1(−). The CM-induced migration was inhibited by a neutralizing antibody against FGF-2 (nFGF-2 ab) or heparitinase, a HS-degrading enzyme, suggesting involvement of FGF-2 and HS in the CM-induced migration. Binding of FGF-2 to FGF receptors in HUVEC cells was increased by CM from C8161 cells, which was significantly enhanced by CM from C8161/Epac1OE but reduced by CM from C8161/Epac1(−). Similar to migration, the CM-induced FGF-2 binding was inhibited by nFGF-2 ab or heparitinase. Since the expression of FGF-2 in C8161 cells was not changed by ablation of Epac1 or Epac1 overexpression, these data suggested that C8161 cells increase migration of WM1552C and HUVEC cells via modification of HS. Finally, tube formation of HUVEC was increased by CM from C8161 cells, but it was inhibited by Epac1 ablation on these cells. Conclusion: Epac1-rich melanoma cells increase migration of Epac1-poor melanoma cell, and endothelial cells via intercellular FGF-2-signaling, suggesting the role of Epac1 in melanoma progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3664. doi:10.1158/1538-7445.AM2011-3664

Heparan Sulfate Proteoglycans Mediate Interstitial Flow Mechanotransduction Regulating MMP-13 Expression and Cell Motility via FAK-ERK in 3D Collagen

BackgroundInterstitial flow directly affects cells that reside in tissues and regulates tissue physiology and pathology by modulating important cellular processes including proliferation, differentiation, and migration. However, the structures that cells utilize to sense interstitial flow in a 3-dimensional (3D) environment have not yet been elucidated. Previously, we have shown that interstitial flow upregulates matrix metalloproteinase (MMP) expression in rat vascular smooth muscle cells (SMCs) and fibroblasts/myofibroblasts via activation of an ERK1/2-c-Jun pathway, which in turn promotes cell migration in collagen. Herein, we focused on uncovering the flow-induced mechanotransduction mechanism in 3D.Methodology/Principal FindingsCleavage of rat vascular SMC surface glycocalyx heparan sulfate (HS) chains from proteoglycan (PG) core proteins by heparinase or disruption of HS biosynthesis by silencing N-deacetylase/N-sulfotransferase 1 (NDST1) suppressed interstitial flow-induced ERK1/2 activation, interstitial collagenase (MMP-13) expression, and SMC motility in 3D collagen. Inhibition or knockdown of focal adhesion kinase (FAK) also attenuated or blocked flow-induced ERK1/2 activation, MMP-13 expression, and cell motility. Interstitial flow induced FAK phosphorylation at Tyr925, and this activation was blocked when heparan sulfate proteoglycans (HSPGs) were disrupted. These data suggest that HSPGs mediate interstitial flow-induced mechanotransduction through FAK-ERK. In addition, we show that integrins are crucial for mechanotransduction through HSPGs as they mediate cell spreading and maintain cytoskeletal rigidity.Conclusions/SignificanceWe propose a conceptual mechanotransduction model wherein cell surface glycocalyx HSPGs, in the presence of integrin-mediated cell-matrix adhesions and cytoskeleton organization, sense interstitial flow and activate the FAK-ERK signaling axis, leading to upregulation of MMP expression and cell motility in 3D. This is the first study to describe a flow-induced mechanotransduction mechanism via HSPG-mediated FAK activation in 3D. This study will be of interest in understanding the flow-related mechanobiology in vascular lesion formation, tissue morphogenesis, cancer cell metastasis, and stem cell differentiation in 3D, and also has implications in tissue engineering.

Heparan sulfate Ndst1 regulates vascular smooth muscle cell proliferation, vessel size and vascular remodeling

Heparan sulfate proteoglycans are abundant molecules in the extracellular matrix and at the cell surface. Heparan sulfate chains are composed of groups of disaccharides whose side chains are modified through a series of enzymatic reactions. Deletion of these enzymes alters heparan sulfate fine structure and leads to changes in cell proliferation and tissue development. The role of heparan sulfate modification has not been explored in the vessel wall. The goal of this study was to test the hypothesis that altering heparan sulfate fine structure would impact vascular smooth muscle cell (VSMC) proliferation, vessel structure, and remodeling in response to injury. A heparan sulfate modifying enzyme, N-deacetylase N-sulfotransferase1 (Ndst1) was deleted in smooth muscle resulting in decreased N- and 2-O sulfation of the heparan sulfate chains. Smooth muscle specific deletion of Ndst1 led to a decrease in proliferating VSMCs and the circumference of the femoral artery in neonatal and adult mice. In response to vascular injury, mice lacking Ndst1 exhibited a significant reduction in lesion formation. Taken together, these data provide new evidence that modification of heparan sulfate fine structure through deletion of Ndst1 is sufficient to decrease VSMC proliferation and alter vascular remodeling.

Glycome and transcriptome regulation of vasculogenesis.

Therapeutic vasculogenesis is an emerging concept that can potentially be harnessed for the management of ischemic pathologies. The present study elucidates the potential coregulation of vasculogenesis by the heparan sulfate glycosaminoglycan-rich cell-surface glycome and the transcriptome. Differentiation of embryonic stem cells into endothelial cells in an in vitro embryoid body is paralleled by an amplification of heparan sulfate glycosaminoglycan sulfation, which correlates with the levels of the enzyme N-deacetylase/N-sulfotransferase 1 (NDST1). Small hairpin RNA-mediated knockdown of NDST1 or modification of heparan sulfate glycosaminoglycans in embryonic stem cells with heparinases or sodium chlorate inhibited differentiation of embryonic stem cells into endothelial cells. This was translated to an in vivo zebrafish embryo model, in which the genetic knockdown of NDST1 resulted in impaired vascularization characterized by a concentration-dependent decrease in intersegmental vessel lumen and a large tail-vessel configuration, which could be rescued by use of exogenous sulfated heparan sulfate glycosaminoglycans. To explore the cross talk between the glycome and the transcriptome during vasculogenesis, we identified by microarray and then validated wild-type and NDST1 knockdown-associated gene-expression patterns in zebrafish embryos. Temporal analysis at 3 developmental stages critical for vasculogenesis revealed a cascade of pathways that may mediate glycocalyx regulation of vasculogenesis. These pathways were intimately connected to cell signaling, cell survival, and cell fate determination. Specifically, we demonstrated that forkhead box O3A/5 proteins and insulin-like growth factor were key downstream signals in this process. The present study for the first time implicates interplay between the glycome and the transcriptome during vasculogenesis, revealing the possibility of harnessing specific cellular glyco-microenvironments for therapeutic vascularization.

Epac increases melanoma cell migration by a heparan sulfate-related mechanism

Melanoma, the most malignant form of human skin cancer, has a poor prognosis due to its strong metastatic ability. It was recently demonstrated that Epac, an effector molecule of cAMP, is involved in regulating cell migration; however, the role of Epac in melanoma cell migration remains unclear. We thus examined whether Epac regulates cell migration and metastasis of melanoma. Epac activation, by either specific agonist or overexpression of Epac, increased melanoma cell migration. Deletion of endogenous Epac with small interfering RNA decreased basal melanoma cell migration. These data suggested a major role of Epac in melanoma cell migration. Epac-induced cell migration was mediated by translocation of syndecan-2, a cell-surface heparan sulfate proteoglycan, to lipid rafts. This syndecan-2 translocation was regulated by tubulin polymerization via the Epac/phosphoinositol-3 kinase pathway. Epac-induced cell migration was also regulated by the production of heparan sulfate, a major extracellular matrix. Epac-induced heparan sulfate production was attributable to the increased expression of N-deacetylase/N-sulfotransferase-1 (NDST-1) accompanied by an increased NDST-1 translation rate. Finally, Epac overexpression enhanced lung colonization of melanoma cells in mice. Taken together, these data indicate that Epac regulates melanoma cell migration/metastasis mostly via syndecan-2 translocation and heparan sulfate production.

Vasculogenesis, a story of glycome and transcriptomal regulation

Impaired vascularization is implicated in diverse pathological conditions such as cardiac ischemia. Therapeutic vasculogenesis is an emerging concept that can be harnessed to treat this condition, contingent upon better molecular understanding. We evaluated the contribution of the microenvironment during vasculogenesis by modifying heparan sulfate gycosaminoglycans (HSGAGs) using a pharmacologic‐genetic approach. Using an embryoid body model, we show that the de novo development of endothelial cells correlates with an increase in the HSGAG‐sulfating enzyme N‐deacetylase‐N‐sulfotransferase‐1 (NDST1) and that inhibiting HSGAGs blocked vasculogenesis. Similarly, in zebrafish embryos, NDST1 knock‐down resulted in a significantly impaired vasculature. To explore the cross‐talk between the glycocalyx and the cellular transcriptome during vasculogenesis, we identified gene expression patterns that are distinct between wild‐type and NDST1‐knock down zebrafish embryos at stages critical for vasculogenesis. Our analyses revealed an emerging picture of a cascade of pathways downstream of the glycocalyx that are intricately connected to cell signaling, matrix, cell survival/apoptosis and cell fate determination.

NDST1-dependent heparan sulfate regulates BMP signaling and internalization in lung development

Heparan sulfate proteoglycans (HSPGs) are required for various signaling pathways, one of which is the bone morphogenetic protein (BMP) signaling pathway. N-deacetylase/N-sulfotransferase-1 (NDST1) participates in synthesizing heparan sulfate (HS) chains of HSPGs, and is involved in bone and lung development. Here, we report that in spite of the redundant expression of Ndst2, Ndst3 and Ndst4 genes, Ndst1(-/-) mice display defective differentiation of lung cells and increased cell proliferation. Loss of Ndst1 in the lung enhances downstream BMP signaling in vivo. Noggin, which is an antagonist of BMP, can rescue the Ndst1(-/-) lung morphogenetic defects in explant cultures. Further studies in vitro indicated that loss of Ndst1 significantly impairs BMP internalization by decreasing BMP binding to endogenous HS. Exogenous heparin can rescue both the BMP signaling and BMP internalization abnormalities in Ndst1(-/-) lung. Thus, we propose that HS regulates BMP signaling by controlling the balance between BMP binding to HS, and that BMP receptors and NDST1-dependent modification are essential for this process. The results suggest that NDST1-dependent HS is essential for proper functioning of BMP in embryonic lung development.

Epac1, an exchange protein activated by cAMP, increases cell migration through syndecan clustering, PI3K activation and heparan sulphate production.

Background: The role of epac1, an exchange protein activated by cAMP, in melanoma migration is largely unknown. Heparan sulfate (HS), a major ECM, and syndecan2, a HS‐binding protein on the cell surface, play important roles in regulating such migration. Syndecan2, when activated, translocates to lipid‐rich plasma microdomains, known as lipid rafts. We thus examined the role of epac1 in HS production and syndecan2 translocation in melanoma migration.Methods: SK‐MEL‐2, a human melanoma cell line, and migration assays with Boyden chambers were employed.Results: Activation of Epac1 by adenoviral Epac1 overexpression or 8pMeOPT, an Epac‐specific cAMP analog, significantly increased cell migration in a time‐ and dose‐dependent manner. Epac1 also increased HS production by 3.5‐fold, and the removal of HS abolished Epac1‐induced migration. Epac1 also increased expression of N‐deacetylase/N‐sulfotransferase‐1 (NDST‐1), a key synthetic enzyme for HS. Sucrose gradient fractionation showed that Epac1 markedly increased syndecan2 translocation to rafts. In addition, disruption of rafts with lipid depletion abolished Epac1‐induced migration.Summary: Epac1 increased migration in malignant melanoma through HS production and syndecan2 translocation to rafts.

Fibroblast growth factor-binding protein and N-deacetylase/N-sulfotransferase-1 expression in type II cells is modulated by heparin and extracellular matrix

Fibroblast growth factors (FGFs) play critical roles in development, maintenance, and repair following injury or disease in the lung. Their activity is modulated by a variety of factors, including FGF-binding protein (FGF-BP; HBp-17) and N-deacetylase/N-sulfotransferase-1 (NDST-1). Functionally, FGF-BP shuttles FGFs from binding sites in ECMs to cell surfaces and enhances FGF binding and signaling, whereas NDST-1 adds sulfate groups to FGF coreceptor proteoglycans and modulates alveolar type II (ATII) cell maturation and differentiation. Since the sulfated nature of ECMs is a critical determinant of their relationship with FGFs, we predicted that ECMs and their sulfation would modulate the expression of FGF-BP and NDST-1. To examine this question, selected culture conditions of rat ATII cells were manipulated [with and without coculture with rat lung fibroblasts (RLFs)] by treatment with heparin or sodium chlorate (inhibitor of sulfation) for 24-96 h. In addition, ECMs biosynthesized by RLFs for up to 10 days before coculture were used as model intervening barriers to communication between alveolar cells and fibroblasts. FGF-BP expression was enhanced in ATII cells by coculture with RLF cells and least suppressed by desulfated heparin. NDST-1 expression in ATII cells was most sensitive to the amount of sulfation in medium and ECM and enhanced by fully sulfated heparin. Preformed ECM appears to supply factors that modify subsequent treatment effects. These results demonstrate a potentially important modulatory influence of sulfated ECMs and fibroblasts on FGF-BP and NDST-1 at the gene expression level.