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Address correspondence to Alan C. Rapraeger, Dept. of Pathology and Laboratory Medicine, University of WisconsinMadison, 1300 University Ave., Madison, WI 53706. Tel.: (608) 262-7577. Fax: (608) 265-3301. E-mail: acraprae{at}facstaff.wisc.edu
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Abstract |
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Key Words: heparan sulfate proteoglycan; fibroblast growth factors; FGF receptors; development; sulfation
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Introduction |
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Binding of growth factors to HS has several potential functions. One established function for FGFs is protection of the growth factors from endogenous proteases (Gospodarowicz and Cheng, 1986). A second is retention of the growth factors at sites of function by the extracellular matrix (Flaumenhaft et al., 1990). Indeed, HS may limit their diffusion and maintain them in active or inactive states, thus generating sites of local activity and morphogenetic boundaries, roles that have been confirmed by emerging genetic studies (Lin et al., 1999; The et al., 1999; Tsuda et al., 1999). Regulation of active or inactive states depends on a third HS function: direct participation of the HS in assembly of the cell surface signaling apparatus. This was first identified in cells deprived of endogenous HS, which curtails FGF binding to its receptor tyrosine kinase (FR) and receptor signaling (Rapraeger et al., 1991; Yayon et al., 1991). This finding has been refined for several members of the FGF family as well as other growth factors, among them hepatocyte growth factor (Sakata et al., 1997; Sergeant et al., 2000), heparan-binding EGF (Kleeff et al., 1998; Paria et al., 1999), and vascular endothelial growth factor (Cohen et al., 1995; Gengrinovitch et al., 1999).
23 members of the FGF family have been identified and each retains an identifiable, although varying, HS-binding domain (Faham et al., 1998; Rapraeger, 2001). These proteins signal through a four-member family of receptor tyrosine kinases (Johnson and Williams, 1993; Szebenyi and Fallon, 1999). The ectodomain of the FR contains three Ig-like domains (D1D3), in which D2 and D3 mediate FGF binding. The interaction of FGF and D3 is a direct proteinprotein interaction using the membrane-proximal half of D3. This region is also subject to splicing variation, which influences FGF binding specificity (Miki et al., 1992; Werner et al., 1992; Ornitz et al., 1996). FGF binding to the D2 region also includes a direct interaction that can vary with FGF type (Chellaiah et al., 1999), and a second interaction that is mediated by a single HS chain that binds both proteins and stabilizes their association. This utilizes HS binding domains that are present in the FGF and within D2 of the FR (Kan et al., 1993). Multiple models for the FRFGFHS interaction have been proposed, attempting to explain how HS promotes binding, oligomerization, and signaling by this monomeric growth factor (Venkataraman et al., 1999; Pellegrini et al., 2000; Schlessinger et al., 2000). In each proposed model, a central question is whether the pattern of sulfation within the HS chain serves to stabilize different FGF and FR pairs, thus regulating the signaling by these growth factors.
It is postulated that HS is encoded with binding specificity by a highly regulated mechanism of synthesis involving sugar epimerization and variable sulfation (Lindahl, 1997; Lindahl et al., 1998; Guimond and Turnbull, 1999). Synthesis of the HS backbone of alternating glucuronate and N-acetylglucosamine residues is followed by the action of other enzymes that epimerize and variably modify regions within the chain by sulfation of specific residues (Wei et al., 1993; Kobayashi et al., 1997; Li et al., 1997; Shworak et al., 1997; Habuchi et al., 1998; Lindahl et al., 1998) (Fig. 1 A). Although the number of sites on a single sugar residue that can be sulfated is relatively few, the potential variation within a span of many saccharides increases geometrically with each subsequent disaccharide added, and leads to the formation of discrete domains within the HS chain. In fact, in vitro experiments with a library of HS saccharides generated by enzymatic or chemical cleavage has demonstrated that FGF binding to HS and signaling depends upon such block sequences of variable sulfation that arise during synthesis of the glycosaminoglycan chain (Turnbull et al., 1992; Guimond et al., 1993; Pye et al., 1998) (Fig. 1 B). However, an important question is whether specific HS binding structures are expressed in a distinct pattern in vivo. If specific binding domains are indeed present within different tissues, the next question is whether they are selectively recognized by specific FGFs, and whether the recognition of these FGFHS complexes by individual FRs is also determined by the HS to which the FGF is bound.
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Results |
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To test these possibilities, soluble extracellular ligand binding domains of FR1c and FR2c fused to human placental alkaline phosphatase (FR1cAP and FR2cAP, respectively) were used as probes to address receptor binding to the FGFHS complexes assembled on the tissue sections. Both FR1c and FR2c are strongly activated by complexes of FGF-2heparin and FGF-4heparin, and so are ideal receptors to use as probes for the detection of tissue-specific HS. Both FR1cAP and FR2cAP were expressed in COS-7 cells and purified from COS-7conditioned medium. Because each FR contains an HS binding domain, receptor constructs were subjected to 1-M NaCl washes during purification to remove any endogenous HS that may have bound the FR. Comparison of constructs purified with or without the 1-M NaCl wash showed no difference in the ability of either FRAP construct to bind to heparin or HS, suggesting that either no endogenous HS copurified with the receptors, or that a sufficiently low amount of HS copurified such that no differences could be detected (unpublished data).
To confirm that the receptor constructs are functional, each receptor was incubated with heparin agarose beads (HABs) in the presence or absence of either FGF-2 or FGF-4. In the absence of FGF, FR1cAP fails to bind HABs (Fig. 6 A, white bar), although FR2cAP does display some binding (Fig. 6 B, white bar). The binding of FR2cAP to HABs is specific, as it is competed with excess soluble heparin (Fig. 6 B, black bar). Additionally, FR2cAP binding to heparin can also be disrupted by washing the beads with 0.35 M NaCl (Fig. 6 B, gray bar). In contrast, in the presence of either FGF-2 or FGF-4, FR1cAP and FR2cAP bind strongly (Fig. 6, A and B, vertical and horizontal lined bars), and this is not disrupted by a 0.35-M NaCl wash. This is consistent with previously published results (Ornitz et al., 1992). As with the binding of FR2cAP alone, formation of a ternary complex of FGFHABFRAP is abrogated by incubation with excess soluble heparin (Fig. 6, A and B, cross-hatched and brick bars).
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HS regulation of FR1c and FR2c signaling
To confirm that the binding of soluble FRAPs to FGFHS complexes on the frozen tissue sections recapitulates the mechanism by which an active FGFHSFGFR signaling complex is assembled, cell proliferation assays were performed with BaF3 cells expressing either FR1c or FR2c (FR1c11 and FR2c2 cells, respectively). The parental BaF3 cells are a lymphoid cell line that is negative for both HS and FGF receptor expression. These cells normally require interleukin (IL)3 for survival; however, cells expressing FR constructs overcome this requirement and survive and proliferate when grown in the presence of the appropriate FGF together with heparin. Both FR1c11 cells and FR2c2 cells have been previously shown to proliferate equally in response to treatment with either FGF-2 or FGF-4 in the presence of heparin (Ornitz et al., 1996). The response to FGF-4, either in the presence or absence of heparin is also demonstrated here, indicating that this FGF activates either FR1c or FR2c in the presence of this glycosaminoglycan (Fig. 10, B and C).
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To test the ability of these receptors to be activated by the FGFHS complexes on the Raji-S1 cells, the BaF3 cells expressing either FR1c or FR2c were cultured with FGF-2 or FGF-4 on fixed monolayers of Raji-S1 cells. Similar to our prior published work (Filla et al., 1998), the FR1c11 cells cultured on fixed monolayers of Raji-S1 cells in the presence of FGF-2 utilize the HS on the Raji cells to bind and respond to the FGF (Fig. 10 B). In contrast, FR1c11 cells do not respond to FGF-4 when grown on a fixed monolayer of Raji-S1 cells, confirming the failure of FR1c to recognize FGF-4 bound to this HS. FR2c2 cells also confirm the results seen using the FGFs and FRAP receptor probes in situ (Fig. 10 C). In contrast to the FR1c11 cells, the FR2c2 cells respond to both FGF-2 and FGF-4 when grown on a fixed monolayer of the Raji-S1 cells shown to express HS that promotes binding of FGF-4 to FR2c.
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Discussion |
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It is also surprising that FGF-4 fails to bind in the heart because of its role in early heart development. There is nothing known about FGF-specific HS expression during heart development, although it is clear that FGF induction of precardiac differentiation in vitro requires HS (Zhu et al., 1996). Heart development from precardiac mesenchyme is initiated before gastrulation by paracrine signaling originating in the endoderm and acting on the adjacent mesodermal layer. This has been studied mostly in the chick embryo in which the underlying endoderm at stage 5 expresses FGF-4, along with FGF-1 and FGF-2. Any of these FGFs will induce the proliferation and differentiation of cardiac myocytes from the precardiac mesenchyme (Lough et al., 1996; Zhu et al., 1996). These same FGFs reappear later during heart chamber formation, where they are expressed in the myocardium with autocrine roles in cardiomyocyte proliferation and differentiation (Zhu et al., 1996). Expression of these FGFs in the heart is subsequently lost at later stages of development. Interestingly, FGF expression in the chick is largely paralleled by expression of FR1, which peaks at stage 24, the stage when heart chamber formation is completed, but persists until day 7 (Sugi et al., 1995). Expression then declines in the ventricle but persists in the atrium. Importantly, these stages of FGF-4 expression in the chick compare with E9E11 in the mouse, which precede the mouse E18 stage examined here. Because FGF-4 fails to bind the heart HS and FR1c recognizes it only rarely when bound elsewhere in the E18 embryo, it suggests that the HS structure may change with development. This is indeed suggested by our preliminary data (unpublished data).
These results suggest that specific differences exist in HS of both the heart and large blood vessels such that FGF-2, but not FGF-4, is recognized. The ability of FGF-2 to bind to most, if not all HS, indicates either that the FGF-2 binding motif in HS is a common HS sequence that is present in all tissues, or that FGF-2 is able to recognize multiple HS sulfation patterns, such that binding is not dramatically affected by variations in HS structure. Where examined in detail using isolated heparin or HS fragments, it has been shown that FGF-2 binding is dependent on the minimum of a pentasaccharide containing 2-O-sulfation (Turnbull et al., 1992; Guimond et al., 1993; Maccarana et al., 1993) (Fig. 1 B). Thus, the presence of 2-O-sulfation may be sufficient for FGF-2 binding, regardless of what other sulfate groups are present.
The failure of FGF-4 to bind in the vascular tissue suggests that the binding motif for FGF-4 is different from that of FGF-2, and that this motif is lacking in the heart and major blood vessels. Although there are fewer data regarding the HS binding requirements of FGF-4 than FGF-2, previous studies have suggested that binding of this growth factor is dependent on HS containing a high content of N-sulfoglucosaminebearing 6-O-sulfate groups (Guimond et al., 1993). This supports the findings here that FGF-2 and FGF-4 recognize different sites; however, these prior experiments, which are aimed primarily at specific types of sulfation (i.e., 2-O-sulfation, or 6-O-sulfation) rather than specific motifs within the HS chain, provide insufficient information on what the specific motifs might be.
Overall, these results suggest that the HS in the walls of vascular elements has very different FGF binding capabilities, which may have far-reaching implications during vascular development and tumor-mediated angiogenesis, where FGFs are known to play an important role (Slavin, 1995; Beckner, 1999). Additionally, the finding that tissue-specific HS regulates FGF binding is likely to have a major impact not only on the 23 FGFs, but also on other HS-binding growth factors, including BMPs, wnts, and hedgehogs, among others (Bernfield et al., 1999).
The ability of FGFs to bind tissue-specific HS fulfills only part of the requirement necessary for activation of FGF signaling, however, as FRs must also recognize specific HS structures in order to bind to and be activated by a particular FGF. Previous studies have shown that FGF-2 activity via FR1c requires a dodecasaccharide (twice the length necessary for binding alone) bearing glucosaminyl-6-O-sulfates in addition to the iduronysyl-2-O-sulfates necessary for FGF-2 binding (Guimond et al., 1993; Pye et al., 1998; Turnbull et al., 1992) (Fig. 1 B). This additional length and sulfation requirement represents a second level of HS specificity that is likely to be important for assembly with FRs leading to signaling. Indeed, heparin depleted of 6-O-sulfates will bind FGF-2 essentially as well as native heparin or HS, but will inhibit the growth factor by failing to assemble with the FR (Guimond et al., 1993). Importantly, recent evidence suggests that it is not merely the presence of 6-O-sulfates that is critical for signaling, but also the location of the 6-O-sulfates on the HS chain that plays a critical role in FR activation (Guimond and Turnbull, 1999).
In the current study, FR1c recognizes FGF-2HS complexes throughout the E18 mouse embryo; this recognition is duplicated by FR2c. Given these data alone, it would be tempting to conclude that HS serves as nothing more than a nonspecific partner for the FGF and receptor. However, When taken in the context of the inability of FR1c to recognize FGF-4HS in the vast majority of sites within the embryo, a different story emerges. The fact that FR1c recognizes FGF-4heparin both in vitro and in vivo, but fails to recognize FGF-4HS at most sites suggests that FRs do indeed require specific HS sulfation sequences in order to recognize a specific FGF. Additionally, the data suggest that the HS sequence necessary for FGF recognition differs between FRs, as FR2c does recognize FGF-4HS throughout the embryo. Indeed, one wonders if FR2c and FR1c are binding exactly the same sites even when they bind to the FGF-2HS complexes. It is entirely possible that these are actually distinct HS chains, or at least distinct sites on HS chains.
Previous studies provide at least partial explanations for the two tissues, namely the liver and the kidney, where FR1c does recognize FGF-4. In the liver, the structure of HS has been characterized as being highly sulfated, and in fact, heparin-like (Lyon et al., 1994). As a result, it is likely that the rare sulfation sequence necessary for FR1c recognition of FGF-4, which exists in heparin, also exists on the heparin-like HS chains present in this site. In the kidney, it has been shown that the HS is heterogeneous, with the detection of at least five different HS species by antibodies generated via phage display (van Kuppevelt et al., 1998). The presence of an HS sequence in the kidney that promotes FR1cFGF-4 complex formation, when combined with the knowledge that both FGF-4 and FR1c are expressed simultaneously in the developing kidney (Cancilla et al., 1999), supports the notion that HS has a regulatory role in FGF-4 signaling during kidney development. The fact that mice that lack the enzyme necessary for 2-O-sulfation of HS fail to develop functional kidneys may also implicate the HS in binding either FGFs or FRs (Bullock et al., 1998).
The lack of binding specificity in the case of FR1c recognition of FGF-2 or FR2c recognition of either FGF-2 or FGF-4 suggests several possibilities. In the case of FGF-2, it is likely that the minimum HS requirements necessary for receptor recognition are common components of HS biosynthesis. This is an intuitive result, as FGF-2 is one of the most widely expressed FGF family members and likely serves to signal in a wide variety of tissues and under a wide variety of physiological and pathological conditions (Baird, 1994; Szebenyi and Fallon, 1999). In this case, HS may serve as a facilitator of FGF-2 signaling rather than as a regulator. However, in the case of FGF-4, HS appears to be serving a regulatory role. It is clear that HS allows recognition of FGF-4 by FR1c in only very specific sites in the E18 stage embryo, whereas FR2c recognizes FGF-4HS on a much broader level. In each of these cases, it will be of interest to examine both FGF and receptor binding at earlier stages of development and in tissues where the FGFs and FRs are expressed and known to play a role, such as limb development in the case of FGF-4 (Martin, 1998). Further studies using other potential FGF receptors (including splice variants) as well as other FGF family members should identify additional specificity of these HS moieties in the regulation of FGF signaling.
Although it is widely accepted that HS is required for the formation of a high affinity FGFFR signaling complex, there are few in vivo data regarding the ability of specific HS structures to regulate complex formation. The method used here provides a highly useful approach for mapping differences in HS structure and relating them directly to FGF activity. Although it is difficult to be certain that the binding of exogenous FGFs to the tissue sections is dependent only on the HS and is not influenced also by endogenous FRs, this seems unlikely as the FGFs bind to sites in the matrix where FRs are not expressed. In addition, we have shown that the putative FGFHS complexes that are formed can be recognized by the exogenous FR probes. Furthermore, the predictions derived from the use of these FGF and FR probes are verified by activity studies using the BaF3 cells expressing FR1c or FR2c. Thus, it seems apparent that tissue-specific HS differentially regulates the binding of FGF-2 and FGF-4 in the developing mouse and also regulates the recognition of these FGFs by FR1c and FR2c in a tissue-specific manner. These results suggest a new paradigm where the formation of specific FGFFR signaling complexes is regulated not only by the presence of HS, but also by site specific expression of distinct HS sequences necessary for complex formation.
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Materials and methods |
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FRAP protein was purified from conditioned medium on an antihuman placental AP-agarose column (Sigma-Aldrich) (Chang et al., 2000). FRAP immobilized on the column was washed with PBS containing 1 M NaCl to remove any endogenous HS that may have been bound to the receptor. The amount of active FRAP protein was quantified by measuring the AP activity of the samples using p-nitrophenyl phosphate (Ornitz et al., 1992). The activities of human placental AP standards (Sigma-Aldrich) of known concentrations were used to estimate FRAP concentration.
In vitro heparan binding assays
Analysis of FRAP binding to FGFheparin complexes was performed using HABs (Bio-Rad Laboratories). FRAP was incubated in tissue culture media (Hepes-buffered RPMI [HbRPMI] + 10% CS + L-gln) at a concentration of 100 nM with 10 µl HABs in either the absence or the presence of 30 nM human recombinant FGF-2, provided by B. Olwin (University of Colorado, Boulder, CO) or 30 nM human recombinant FGF-4 (R&D Systems) for 1 h at room temperature on a rotator. The HABs bearing FRAP were washed three times with either PBS or PBS containing 350 mM NaCl, resuspended in PBS, and loaded into 96-well plates with an equal volume of AP substrate solution and AP activity determined by absorbance at 405 nm. The amount of receptor bound was calculated as a percent of the total amount of receptor added to each treatment group.
In situ HS binding assays
Frozen tissue sections were incubated for FGF detection as described (Friedl et al., 1997). Sections from E16 and E18 stage CD-1 mouse embryos (Charles River Laboratories) were cut at a thickness of 5 µm, air dried, and then fixed in 4% paraformaldehyde on ice. Two washes with cold 0.05% NaBH4 followed by overnight treatment in PBS containing 0.1 M glycine at 4°C served to reduce autofluoresence of the tissues. Sections were blocked for 1 h at room temperature in TBS containing 10% fetal calf serum (Hyclone). Incubation of sections with FGF was for 1 h with 30 nM FGF-2 or 30 nM FGF-4. After three washes with TBS, bound FGF-2 was detected with 1:500 DE6 antiFGF-2 antibody (a gift of DuPont), or bound FGF-4 was detected with 1:100 AF235 antiFGF-4 antibody (R&D Systems) and Alexa-conjugated secondary antibodies (Molecular Probes).
Treatment of sections with 0.006 IU/ml heparin lyase I and heparin lyase III (referred to as heparitinase treatment) (Seikagaku America) for 2 h at 37°C, followed by addition of fresh enzyme for an additional 2 h completely removes endogenous HS. The unsaturated glucuronate remaining on the core protein is recognized by mAb3G10 (Seikagaku America), allowing examination of total HS distribution. Sections were incubated with 1:200 dilution of mAb3G10 in TBS containing 10% fetal calf serum for 1 h at room temperature, followed by 1:300 Cy3-conjugated donkey antimouse secondary antibody (Molecular Probes). Staining of sections without prior enzyme treatment shows no 3G10 staining (unpublished data).
For analysis of FRAP binding to FGF immobilized on endogenous HS, frozen sections were incubated with 30 nM native FGF-2 or FGF-4 for 1 h, then washed and incubated for an additional hour with 100 nM FR1cAP or FR2cAP in TBS containing 10% fetal calf serum. Sections were then treated with polyclonal rabbit anti-PLAP (Biomeda Corp.) for 30 min followed by Alexa 546conjugated goat antirabbit antibody (Molecular Probes) for 30 min. Parallel sections were incubated with 1:10 fluorescein-conjugated PECAM-1 to identify capillaries. Parallel sections were incubated with 1:300 smooth muscle actin monoclonal antibody, a gift of Dr. Zsuzsa Fabry (University of WisconsinMadison, Madison, WI) to identify large blood vessels.
Cell culture
MAECs were obtained from Dr. Robert Auerbach (University of WisconsinMadison, Madison, WI) and cultured in DME, 10% fetal calf serum, 4 mM L-glutamine, and 1% antibiotics (10,000 U penicillin/10 mg/ml streptomycin). Generation of Raji-S1 Burkitt's lymphoma cells has been described previously (Lebakken and Rapraeger, 1996). Raji cells are negative for proteoglycan expression and have been transfected with the cDNA for mouse syndecan-1. Raji-S1 cells were cultured in RPMI 1640, 10% fetal bovine serum, 4 mM glutamine, 1.5 mg/ml G418 sulfate, and 1% antibiotics. FR1c11 and FR2c2 cells, BaF3 lymphoid cells expressing FR1c and FR2c, respectively, were provided by Dr. David Ornitz. FR1c11 and FR2c2 cells were cultured in RPMI 1640, 10% fetal calf serum, 10% WEHI-3conditioned medium, 4 mM L-glutamine, 1% antibiotics, and 0.0035% ß-mercaptoethanol.
Morphology assay
MAECs were plated in DME containing 10% fetal calf serum at a concentration of 4 x 103 cells/well in 8-well chamber slides (LAB-TEK). After 24 h, cells were washed with serum-free DME, and incubated at 37°C in serum free DME with 10 nM FGF in the absence or presence of 10 nM porcine intestinal mucosa heparin (Sigma-Aldrich) for 72 h. Cells were then fixed in 1% glutaraldehyde and photographed.
BaF3 proliferation assays
FR1c11 and FR2c2 cells were added to 96-well flat bottom plates (Fisher Scientific) at a concentration of 105 cells/ml in IL-3deficient media. FGF (10 nM) was added and incubated at 37°C for 72 h in the presence or absence of 10 nM porcine intestinal mucosa heparin. After 72 h, CellTiter 96 AQueous One Solution reagent (Promega) was added to quantify relative cell numbers using the manufacturer's instructions.
For Raji-S1 cellmediated survival/proliferation of the BaF3 cells, 2.5 x 106 Raji-S1 cells/ml were allowed to adhere as a confluent monolayer to 96-well flat bottom plates for 2 h at 37°C in Hepes-buffered RPMI [HbRPMI], 0.1% BSA, 4 mM L-glutamine, and 1% antibiotics. The monolayer was fixed for 1 h in 0.5% glutaraldehyde, followed by three washes in PBS containing 0.2 M glycine, and incubated overnight in RPMI containing 10% CS, 4mM L-glutamine, and 1% antibiotics. FR1c11 and FR2c2 cells were added to the Raji-S1 monolayer the next day in IL-3deficient media with or without FGF and treated as described above.
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Footnotes |
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Acknowledgments |
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Submitted: 31 May 2001
Revised: 27 September 2001
Accepted: 1 October 2001
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References |
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Aird, W.C., J.M. Edelberg, H. Weiler-Guettler, W.W. Simmons, T.W. Smith, and R.D. Rosenberg. 1997. Vascular bedspecific expression of an endothelial cell gene is programmed by the tissue microenvironment. J. Cell Biol. 138:11171124.
Andres, J.L., K. Stanley, S. Cheifetz, and J. Massague. 1989. Membrane-anchored and soluble forms of betaglycan, a polymorphic proteoglycan that binds transforming growth factorß. J. Cell Biol. 109:31373145.[Abstract]
Baird, A. 1994. Potential mechanisms regulating the extracellular activities of basic fibroblast growth factor (FGF-2). Mol. Reprod. Dev. 39:4348.[Medline]
Bastaki, M., E.E. Nelli, P. Dell'Era, M. Rusnati, M.P. Molinari-Tosatti, S. Parolini, R. Auerbach, L.P. Ruco, L. Possati, and M. Presta. 1997. Basic fibroblast growth factor-induced angiogenic phenotype in mouse endothelium. A study of aortic and microvascular endothelial cell lines. Arterioscler. Thromb. Vasc. Biol. 17:454464.
Beckner, M.E. 1999. Factors promoting tumor angiogenesis. Cancer Invest. 17:594623.[Medline]
Bennett, K.L., D.G. Jackson, J.C. Simon, E. Tanczos, R. Peach, B. Modrell, I. Stamenkovic, G. Plowman, and A. Aruffo. 1995. CD44 isoforms containing exon V3 are responsible for the presentation of heparin-binding growth factor. J. Cell Biol. 128:687698.[Abstract]
Bernfield, M., M. Gotte, P.W. Park, O. Reizes, M.L. Fitzgerald, J. Lincecum, and M. Zako. 1999. Functions of cell surface heparan sulfate proteoglycans. Annu. Rev. Biochem. 68:729777.[Medline]
Bullock, S.L., J.M. Fletcher, R.S. Beddington, and V.A. Wilson. 1998. Renal agenesis in mice homozygous for a gene trap mutation in the gene encoding heparan sulfate 2-sulfotransferase. Genes Dev. 12:18941906.
Cancilla, B., M.D. Ford-Perriss, and J.F. Bertram. 1999. Expression and localization of fibroblast growth factors and fibroblast growth factor receptors in the developing rat kidney. Kidney Int. 56:20252039.[Medline]
Chang, Z., K. Meyer, A.C. Rapraeger, and A. Friedl. 2000. Differential ability of heparan sulfate proteoglycans to assemble the fibroblast growth factor receptor complex in situ. FASEB J. 14:137144.
Chellaiah, A., W. Yuan, M. Chellaiah, and D.M. Ornitz. 1999. Mapping ligand binding domains in chimeric fibroblast growth factor receptor molecules. Multiple regions determine ligand binding specificity. J. Biol. Chem. 274:3478534794.
Cohen, T., H. Gitay-Goren, R. Sharon, M. Shibuya, R. Halaban, B.Z. Levi, and G. Neufeld. 1995. VEGF121, a vascular endothelial growth factor (VEGF) isoform lacking heparin binding ability, requires cell-surface heparan sulfates for efficient binding to the VEGF receptors of human melanoma cells. J. Biol. Chem. 270:1132211326.
Dell'Era, P., M. Belleri, H. Stabile, M.L. Massardi, D. Ribatti, and M. Presta. 2001. Paracrine and autocrine effects of fibroblast growth factor-4 in endothelial cells. Oncogene. 20:26552663.[Medline]
Delli-Bovi, P., A.M. Curatola, K.M. Newman, Y. Sato, D. Moscatelli, R.M. Hewick, D.B. Rifkin, and C. Basilico. 1988. Processing, secretion, and biological properties of a novel growth factor of the fibroblast growth factor family with oncogenic potential. Mol. Cell. Biol. 8:29332941.[Medline]
Faham, S., R.J. Linhardt, and D.C. Rees. 1998. Diversity does make a difference: fibroblast growth factor-heparin interactions. Curr. Opin. Struct. Biol. 8:578586.[Medline]
Filla, M.S., P. Dam, and A.C. Rapraeger. 1998. The cell surface proteoglycan syndecan-1 mediates fibroblast growth factor-2 binding and activity. J. Cell. Physiol. 174:310321.[Medline]
Filmus, J. 2001. Glypicans in growth control and cancer. Glycobiology. 11:19R23R.
Flaumenhaft, R., D. Moscatelli, and D.B. Rifkin. 1990. Heparin and heparan sulfate increase the radius of diffusion and action of basic fibroblast growth factor. J. Cell Biol. 111:16511659.[Abstract]
Friedl, A., Z. Chang, A. Tierney, and A.C. Rapraeger. 1997. Differential binding of fibroblast growth factor-2 and -7 to basement membrane heparan sulfate: comparison of normal and abnormal human tissues. Am. J. Pathol. 150:14431455.[Abstract]
Gengrinovitch, S., B. Berman, G. David, L. Witte, G. Neufeld, and D. Ron. 1999. Glypican-1 is a VEGF165 binding proteoglycan that acts as an extracellular chaperone for VEGF165. J. Biol. Chem. 274:1081610822.
Gospodarowicz, D., and J. Cheng. 1986. Heparin protects basic and acidic FGF from inactivation. J. Cell Physiol. 128:475484.[Medline]
Guimond, S.E., and J.E. Turnbull. 1999. Fibroblast growth factor receptor signalling is dictated by specific heparan sulphate saccharides. Curr. Biol. 9:13431346.[Medline]
Guimond, S., M. Maccarana, B.B. Olwin, U. Lindahl, and A.C. Rapraeger. 1993. Activating and inhibitory heparin sequences for FGF-2 (basic FGF). Distinct requirements for FGF-1, FGF-2, and FGF-4. J. Biol. Chem. 268:2390623914.
Habuchi, H., M. Kobayashi, and K. Kimata. 1998. Molecular characterization and expression of heparan-sulfate 6-sulfotransferase. Complete cDNA cloning in human and partial cloning in Chinese hamster ovary cells. J. Biol. Chem. 273:92089213.
Iozzo, R.V. 1998. Matrix proteoglycans: from molecular design to cellular function. Annu. Rev. Biochem. 67:609652.[Medline]
Jackson, D.G., J.I. Bell, R. Dickinson, J. Timans, J. Shields, and N. Whittle. 1995. Proteoglycan forms of the lymphocyte homing receptor CD44 are alternatively spliced variants containing the v3 exon. J. Cell Biol. 128:673685.[Abstract]
Johnson, D.E., and L.T. Williams. 1993. Structural and functional diversity in the FGF receptor multigene family. Adv. Cancer Res. 60:141.[Medline]
Kan, M., F. Wang, J. Xu, J.W. Crabb, J. Hou, and W.L. McKeehan. 1993. An essential heparin-binding domain in the fibroblast growth factor receptor kinase. Science. 259:19181921.[Medline]
Kleeff, J., T. Ishiwata, A. Kumbasar, H. Friess, M.W. Buchler, A.D. Lander, and M. Korc. 1998. The cell-surface heparan sulfate proteoglycan glypican-1 regulates growth factor action in pancreatic carcinoma cells and is overexpressed in human pancreatic cancer. J. Clin. Invest. 102:16621673.
Kobayashi, M., H. Habuchi, M. Yoneda, O. Habuchi, and K. Kimata. 1997. Molecular cloning and expression of Chinese hamster ovary cell heparan-sulfate 2-sulfotransferase. J. Biol. Chem. 272:1398013985.
Lebakken, C.S., and A.C. Rapraeger. 1996. Syndecan-1 mediates cell spreading in transfected human lymphoblastoid (Raji) cells. J. Cell Biol. 132:12091221.[Abstract]
Li, J., A. Hagner-McWhirter, L. Kjellen, J. Palgi, M. Jalkanen, and U. Lindahl. 1997. Biosynthesis of heparin/heparan sulfate. cDNA cloning and expression of D-glucuronyl C5-epimerase from bovine lung. J. Biol. Chem. 272:2815828163.
Lin, X., E.M. Buff, N. Perrimon, and A.M. Michelson. 1999. Heparan sulfate proteoglycans are essential for FGF receptor signaling during Drosophila embryonic development. Development. 126:37153723.
Lindahl, U. 1997. Heparan sulfate: a polyanion with multiple messages. Pure Appl. Chem. 69:18971902.
Lindahl, U., M. Kusche-Gullberg, and L. Kjellen. 1998. Regulated diversity of heparan sulfate. J. Biol. Chem. 273:2497924982.
Lough, J., M. Barron, M. Brogley, Y. Sugi, D.L. Bolender, and X. Zhu. 1996. Combined BMP-2 and FGF-4, but neither factor alone, induces cardiogenesis in non-precardiac embryonic mesoderm. Dev. Biol. 178:198202.[Medline]
Lyon, M., J.A. Deakin, and J.T. Gallagher. 1994. Liver heparan sulfate structure. A novel molecular design. J. Biol. Chem. 269:1120811215.
Maccarana, M., B. Casu, and U. Lindahl. 1993. Minimal sequence in heparin/heparan sulfate required for binding of basic fibroblast growth factor. J. Biol. Chem. 268:2389823905.
Martin, G.R. 1998. The roles of FGFs in the early development of vertebrate limbs. Genes Dev. 12:15711586.
Miki, T., D.P. Bottaro, T.P. Fleming, C.L. Smith, W.H. Burgess, A.M. Chan, and S.A. Aaronson. 1992. Determination of ligand-binding specificity by alternative splicing: two distinct growth factor receptors encoded by a single gene. Proc. Natl. Acad. Sci. USA. 89:246250.[Abstract]
Miyagawa, K., H. Sakamoto, T. Yoshida, Y. Yamashita, Y. Mitsui, M. Furusawa, S. Maeda, F. Takaku, T. Sugimura, and M. Terada. 1988. hst-1 transforming protein: expression in silkworm cells and characterization as a novel heparin-binding growth factor. Oncogene. 3:383389.[Medline]
Noonan, D.M., A. Fulle, P. Valente, S. Cai, E. Horigan, M. Sasaki, Y. Yamada, and J.R. Hassell. 1991. The complete sequence of perlecan, a basement membrane heparan sulfate proteoglycan, reveals extensive similarity with laminin A chain, low density lipoprotein-receptor, and the neural cell adhesion molecule. J. Biol. Chem. 266:2293922947.
Ornitz, D.M., A. Yayon, J.G. Flanagan, C.M. Svahn, E. Levi, and P. Leder. 1992. Heparin is required for cell-free binding of basic fibroblast growth factor to a soluble receptor and for mitogenesis in whole cells. Mol.Cell Biol. 12:240247.[Abstract]
Ornitz, D.M., J. Xu, J.S. Colvin, D.G. McEwen, C.A. MacArthur, F. Coulier, G. Gao, and M. Goldfarb. 1996. Receptor specificity of the fibroblast growth factor family. J. Biol. Chem. 271:1529215297.
Paria, B.C., K. Elenius, M. Klagsbrun, and S.K. Dey. 1999. Heparin-binding EGF-like growth factor interacts with mouse blastocysts independently of ErbB1: a possible role for heparan sulfate proteoglycans and ErbB4 in blastocyst implantation. Development. 126:19972005.
Park, P.W., O. Reizes, and M. Bernfield. 2000. Cell surface heparan sulfate proteoglycans: selective regulators of ligand-receptor encounters. J. Biol. Chem. 275:2992329926.
Pellegrini, L., D.F. Burke, F. von Delft, B. Mulloy, and T.L. Blundell. 2000. Crystal structure of fibroblast growth factor receptor ectodomain bound to ligand and heparin. Nature. 407:10291034.[Medline]
Pye, D.A., R.R. Vives, J.E. Turnbull, P. Hyde, and J.T. Gallagher. 1998. Heparan sulfate oligosaccharides require 6-O-sulfation for promotion of basic fibroblast growth factor mitogenic activity. J. Biol. Chem. 273:2293622942.
Rapraeger, A.C. 2001. Heparan sulfate-growth factor interactions. Methods in Cell Adhesion. J.C. Adams, editor. Academic Press, New York. In press.
Rapraeger, A.C., A. Krufka, and B.B. Olwin. 1991. Requirement of heparan sulfate for bFGF-mediated fibroblast growth and myoblast differentiation. Science. 252:17051708.[Medline]
Sakata, H., S.J. Stahl, W.G. Taylor, J.M. Rosenberg, K. Sakaguchi, P.T. Wingfield, and J.S. Rubin. 1997. Heparin binding and oligomerization of hepatocyte growth factor/scatter factor isoforms. Heparan sulfate glycosaminoglycan requirement for Met binding and signaling. J. Biol. Chem. 272:94579463.
Schlessinger, J., A.N. Plotnikov, O.A. Ibrahimi, A.V. Eliseenkova, B.K. Yeh, A. Yayon, R.J. Linhardt, and M. Mohammadi. 2000. Crystal structure of a ternary FGF-FGFR-heparin complex reveals a dual role for heparin in FGFR binding and dimerization. Mol. Cell. 6:743750.[Medline]
Sergeant, N., M. Lyon, P.S. Rudland, D.G. Fernig, and M. Delehedde. 2000. Stimulation of DNA synthesis and cell proliferation of human mammary myoepithelial-like cells by hepatocyte growth factor/scatter factor depends on heparan sulfate proteoglycans and sustained phosphorylation of mitogen-activated protein kinases p42/44. J. Biol. Chem. 275:1709417099.
Shworak, N.W., J. Liu, L.M. Fritze, J.J. Schwartz, L. Zhang, D. Logeart, and R.D. Rosenberg. 1997. Molecular cloning and expression of mouse and human cDNAs encoding heparan sulfate D-glucosaminyl 3-O-sulfotransferase. J. Biol. Chem. 272:2800828019.
Slavin, J. 1995. Fibroblast growth factors: at the heart of angiogenesis. Cell. Biol. Int. 19:431444.[Medline]
Sugi, Y., J. Sasse, M. Barron, and J. Lough. 1995. Developmental expression of fibroblast growth factor receptor-1 (cek-1; flg) during heart development. Dev. Dyn. 202:115125.[Medline]
Szebenyi, G., and J.F. Fallon. 1999. Fibroblast growth factors as multifunctional signaling factors. Int. Rev. Cytol. 185:45106.[Medline]
The, I., Y. Bellaiche, and N. Perrimon. 1999. Hedgehog movement is regulated through tout velu-dependent synthesis of a heparan sulfate proteoglycan. Mol. Cell. 4:633639.[Medline]
Tsuda, M., K. Kamimura, H. Nakato, M. Archer, W. Staatz, B. Fox, M. Humphrey, S. Olson, T. Futch, V. Kaluza, et al. 1999. The cell-surface proteoglycan Dally regulates Wingless signalling in Drosophila. Nature. 400:276280.[Medline]
Turnbull, J.E., D.G. Fernig, Y. Ke, M.C. Wilkinson, and J.T. Gallagher. 1992. Identification of the basic fibroblast growth factor binding sequence in fibroblast heparan sulfate. J. Biol. Chem. 267:1033710341.
van Kuppevelt, T.H., M.A. Dennissen, W.J. van Venrooij, R.M. Hoet, and J.H. Veerkamp. 1998. Generation and application of type-specific anti-heparan sulfate antibodies using phage display technology. Further evidence for heparan sulfate heterogeneity in the kidney. J. Biol. Chem. 273:1296012966.
Venkataraman, G., R. Raman, V. Sasisekharan, and R. Sasisekharan. 1999. Molecular characteristics of fibroblast growth factor-fibroblast growth factor receptor-heparin-like glycosaminoglycan complex. Proc. Natl. Acad. Sci. USA. 96:36583663.
Wei, Z., S.J. Swiedler, M. Ishihara, A. Orellana, and C.B. Hirschberg. 1993. A single protein catalyzes both N-deacetylation and N-sulfation during the biosynthesis of heparan sulfate. Proc. Natl. Acad. Sci. USA. 90:38853888.[Abstract]
Werner, S., D.S. Duan, C. de Vries, K.G. Peters, D.E. Johnson, and L.T. Williams. 1992. Differential splicing in the extracellular region of fibroblast growth factor receptor 1 generates receptor variants with different ligand-binding specificities. Mol. Cell. Biol. 12:8288.[Abstract]
Yayon, A., M. Klagsbrun, J.D. Esko, P. Leder, and D.M. Ornitz. 1991. Cell surface, heparin-like molecules are required for binding of basic fibroblast growth factor to its high affinity receptor. Cell. 64:841848.[Medline]
Yoshida, T., K. Ishimaru, H. Sakamoto, J. Yokota, S. Hirohashi, K. Igarashi, K. Sudo, and M. Terada. 1994. Angiogenic activity of the recombinant hst-1 protein. Cancer Lett. 83:261268.[Medline]
Zhu, X., J. Sasse, D. McAllister, and J. Lough. 1996. Evidence that fibroblast growth factors 1 and 4 participate in regulation of cardiogenesis. Dev. Dyn. 207:429438.[Medline]
Zimmermann, P., and G. David. 1999. The syndecans, tuners of transmembrane signaling. FASEB J. 13:S91S100.