C-terminal Tail of FGF19 Determines Its Specificity toward Klotho Co-receptors

Wu, Xiaohong; Lemon, Bryan; Li, Xiaofan; Gupte, Jamila; Weiszmann, Jennifer; Stevens, Jennitte; Hawkins, Nessa; Shen, Wenyan David; Lindberg, Richard A.; Chen, Jinlong; Tian, Hui; Li, Yang

doi:10.1074/jbc.m803319200

Cited by 79 publications

(66 citation statements)

References 20 publications

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“…Moreover, klotho gene can transcribe a secreted form of klotho by alternative RNA splicing encoding only the KL1 domain (13,14,23). Only full-length klotho can function as a coreceptor for FGF23 (19,44). Indeed, KL1 did not affect signaling by FGF23 in MDCT cells (Fig.…”

Section: Discussionmentioning

confidence: 99%

KL1 Internal Repeat Mediates Klotho Tumor Suppressor Activities and Inhibits bFGF and IGF-I Signaling in Pancreatic Cancer

Abramovitz

Rubinek

Ligumsky

et al. 2011

Clinical Cancer Research

126

123

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Purpose: Klotho is a transmembrane protein which can be shed, act as a circulating hormone and modulate the insulin-like growth factor (IGF)-I and the fibroblast growth factor (FGF) pathways. We have recently identified klotho as a tumor suppressor in breast cancer. Klotho is expressed in the normal pancreas and both the IGF-I and FGF pathways are involved in pancreatic cancer development. We, therefore, undertook to study the expression and activity of klotho in pancreatic cancer.Experimental Design: Klotho expression was studied using immunohistochemistry and quantitative RT-PCR. Effects of klotho on cell growth were assessed in the pancreatic cancer cells Panc1, MiaPaCa2, and Colo357, using colony and MTT assays and xenograft models. Signaling pathway activity was measured by Western blotting.Results: Klotho expression is downregulated in pancreatic adenocarcinoma. Overexpression of klotho, or treatment with soluble klotho, reduced growth of pancreatic cancer cells in vitro and in vivo, and inhibited activation of the IGF-I and the bFGF pathways. KL1 is a klotho subdomain formed by cleavage or alternative splicing. Compared with the full-length protein, KL1 showed similar growth inhibitory activity but did not promote FGF23 signaling. Thus, its administration to mice showed favorable safety profile.Conclusions: These studies indicate klotho as a potential tumor suppressor in pancreatic cancer, and suggest, for the first time, that klotho tumor suppressive activities are mediated through its KL1 domain. These results suggest the use of klotho or KL1 as potential strategy for the development of novel therapeutic interventions for pancreatic cancer. Clin Cancer Res; 17(13); 4254-66. Ó2011 AACR.

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Section: Discussionmentioning

confidence: 99%

KL1 Internal Repeat Mediates Klotho Tumor Suppressor Activities and Inhibits bFGF and IGF-I Signaling in Pancreatic Cancer

Abramovitz

Rubinek

Ligumsky

et al. 2011

Clinical Cancer Research

126

123

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“…Since both FGF19 and FGF21 bind to ␤Klotho, it raised the question whether these ligands bind to a shared site on ␤Klotho or whether each ligand has its own distinct binding site. Previous studies have suggested that, reminiscent of FGF23, FGF19 and FGF21 use their C-terminal tail to bind ␤Klotho (41,73,75). Based on this knowledge, we set up an SPR-based competition binding assay to examine whether the isolated C-terminal tail peptide of FGF19 (FGF19 C-tail [ Fig.…”

Section: Resultsmentioning

confidence: 99%

Klotho Coreceptors Inhibit Signaling by Paracrine Fibroblast Growth Factor 8 Subfamily Ligands

Goetz

Ohnishi

Ding

et al. 2012

Molecular and Cellular Biology

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e It has been recently established that Klotho coreceptors associate with fibroblast growth factor (FGF) receptor tyrosine kinases (FGFRs) to enable signaling by endocrine-acting FGFs. However, the molecular interactions leading to FGF-FGFR-Klotho ternary complex formation remain incompletely understood. Here, we show that in contrast to ␣Klotho, ␤Klotho binds its cognate endocrine FGF ligand (FGF19 or FGF21) and FGFR independently through two distinct binding sites. FGF19 and FGF21 use their respective C-terminal tails to bind to a common binding site on ␤Klotho. Importantly, we also show that Klotho coreceptors engage a conserved hydrophobic groove in the immunoglobulin-like domain III (D3) of the "c" splice isoform of FGFR. Intriguingly, this hydrophobic groove is also used by ligands of the paracrine-acting FGF8 subfamily for receptor binding. Based on this binding site overlap, we conclude that while Klotho coreceptors enhance binding affinity of FGFR for endocrine FGFs, they actively suppress binding of FGF8 subfamily ligands to FGFR. Fibroblast growth factor (FGF) signaling plays pleiotropic roles in metazoan development and metabolism (5, 24). Based on sequence homology and phylogenetic and structural considerations, the 18 mammalian FGF ligands are grouped into five paracrine-acting subfamilies and one endocrine-acting subfamily comprising FGF19, FGF21, and FGF23 (24,43). Paracrine FGFs have high affinity for pericellular heparan sulfate (HS) glycosaminoglycans (3, 5) and form distinct morphogenetic gradients in the pericellular matrix (27, 39) to fulfill essential roles during embryonic development (7,24,65). In contrast, endocrine FGFs exhibit poor affinity for HS (3, 15) and thus are able to enter the blood circulation to regulate key metabolic processes, including bile acid homeostasis (18,20,36) and hepatic glucose and protein metabolism (30, 57) (FGF19), glucose and lipid metabolism (4, 21, 29, 58) (FGF21), and vitamin D and phosphate homeostasis (1, 59, 62) (FGF23). These hormone-like FGFs have taken center stage in drug discovery for a number of inherited and acquired metabolic disorders (5, 6).Mammalian FGFs signal through four FGF receptor (FGFR) tyrosine kinases (FGFR1 to FGFR4) and their alternatively spliced isoforms (23, 43). The extracellular domain of a prototypical FGFR consists of three immunoglobulin-like domains (D1 to D3), and structural and biochemical studies have established that the region including D2, D3, and the D2-D3 linker comprises the minimal ligand-binding domain (54,55,63). The ligand-binding specificity of FGFR1 to FGFR3 is primarily regulated by a tissuespecific splicing in D3 of these receptors that generates "b" and "c" isoforms (9,26,42,52). Structural studies have revealed that this splicing alters the primary amino acid sequence of key ligandbinding loops/pockets in D3 (50,74).In addition to mediating paracrine FGF gradient formation in the pericellular matrix, HS is required for enhancing the affinity of paracrine FGF for FGFR and promoting dimerization of ligan...

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“…This requirement for either ␣Klotho or ␤Klotho provides another level of selectivity to FGFR signaling and may restrict the target tissues for this endocrine FGF subfamily. We showed that the Klotho-interaction domain of FGF19 subfamily members resides in their C-terminal region (12). The sole exception for this co-receptor requirement is the ability of FGF19 to bind directly to FGFR4, but not to other FGFRs, in the absence of the Klothos (11,13).…”

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confidence: 97%

Selective activation of FGFR4 by an FGF19 variant does not improve glucose metabolism in ob/ob mice

Lemon

et al. 2009

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

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FGF19 is a hormone that regulates bile acid and glucose homeostasis. Progress has been made in identifying cofactors for receptor activation. However, several functions of FGF19 have not yet been fully defined, including the actions of FGF19 on target tissues, its FGF receptor specificity, and the contributions of other cofactors, such as heparin. Here, we explore the requirements for FGF19-FGFR/co-receptor interactions and signaling in detail. We show that ␤Klotho was essential for FGF19 interaction with FGFRs 1c, 2c, and 3c, but FGF19 was able to interact directly with FGFR4 in the absence of ␤Klotho in a heparin-dependent manner. Further, FGF19 activated FGFR4 signaling in the presence or absence of ␤Klotho, but activation of FGFRs 1c, 2c, or 3c was completely ␤Klotho dependent. We then generated an FGF19 molecule, FGF19dCTD, which has a deletion of the C-terminal region responsible for ␤Klotho interaction. We determined that ␤Klotho-dependent FGFR1c, 2c, and 3c interactions and activation were abolished, and ␤Klotho-independent FGFR4 activation was preserved; therefore, FGF19dCTD is an FGFR4-specific activator. This unique FGF19 molecule specifically activated FGFR4-dependent signaling in liver and suppressed CYP7A1 expression in vivo, but was unable to activate signaling in adipose where FGFR4 expression is very low. Interestingly, unlike FGF19, treatment of ob/ob mice with FGF19dCTD failed to improve glucose levels and insulin sensitivity. These results suggest that FGF19-regulated liver bile acid metabolism could be independent of its glucose-lowering effect, and direct FGFR activation in adipose tissue may play an important role in the regulation of glucose homeostasis.T he FGF19 subfamily of fibroblast growth factors (FGFs), consisting of FGF19, FGF21, and FGF23, has been implicated in the regulation of many metabolic processes (1-4). One of the properties of this subfamily is atypical heparin binding (5). FGFs generally have a positively charged heparin-binding region that helps create high-affinity interactions with cell surface FGF receptors (FGFRs) (6). Compared with other FGFs, the crystal structures of FGF19 and FGF23 revealed a disrupted heparinbinding motif, which could weaken interactions with heparin or heparan sulfate (5, 7). Consistent with this, direct measurement of affinity for immobilized heparin showed that FGF21 did not interact with heparin and that FGF19 and FGF23 bound to heparin weakly compared with the affinity of immobilized heparin for the other FGFs (6). Consequently, members of this subfamily may not be retained by heparin-containing tissues or the extracellular matrix, thus making it possible for them to function as endocrine hormones.Another distinctive feature of this subfamily is the requirement for the co-receptors ␣Klotho or ␤Klotho in FGFR signaling complexes (8-11). With reduced affinity toward heparin, FGF19, 21, and 23 may use ␣Klotho or ␤Klotho proteins to stabilize their interactions with FGFRs to activate downstream signaling pathways. This requirement for either...

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C-terminal Tail of FGF19 Determines Its Specificity toward Klotho Co-receptors

Cited by 79 publications

References 20 publications

KL1 Internal Repeat Mediates Klotho Tumor Suppressor Activities and Inhibits bFGF and IGF-I Signaling in Pancreatic Cancer

KL1 Internal Repeat Mediates Klotho Tumor Suppressor Activities and Inhibits bFGF and IGF-I Signaling in Pancreatic Cancer

Klotho Coreceptors Inhibit Signaling by Paracrine Fibroblast Growth Factor 8 Subfamily Ligands

Selective activation of FGFR4 by an FGF19 variant does not improve glucose metabolism in ob/ob mice

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