Fibroblast growth factors, their receptors and signaling.
TL;DR: FGF signaling also appears to play a role in tumor growth and angiogenesis, and autocrine FGF signaling may be particularly important in the progression of steroid hormone-dependent cancers to a hormone-independent state.
Abstract: Fibroblast growth factors (FGFs) are small polypeptide growth factors, all of whom share in common certain structural characteristics, and most of whom bind heparin avidly. Many FGFs contain signal peptides for secretion and are secreted into the extracellular environment, where theycan bind to the heparan-like glycosaminoglycans (HLGAGs) of the extracellular matrix (ECM). From this reservoir, FGFs mayact directlyon target cells, or theycan be released through digestion of the ECM or the activityof a carrier protein, a secreted FGF binding protein. FGFs bind specific receptor tyrosine kinases in the context of HLGAGs and this binding induces receptor dimerization and activation, ultimatelyresulting in the activation of various signal transduction cascades. Some FGFs are potent angiogenic factors and most playimportant roles in embry onic development and wound healing. FGF signaling also appears to playa role in tumor growth and angiogenesis, and autocrine FGF signaling maybe particularlyimportant in the progression of steroid hormone-dependent cancers to a hormone-independent state.
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TL;DR: The study indicated that morphine-induced extracellular HSP70 was an alternative way for the activation of TLR4-NLRP3 in analgesic tolerance and suggested a promising target, KATP channel and a new leading compound, glibenclamide, for treating morphine tolerance.
Abstract: Long-term use of morphine induces analgesic tolerance, which limits its clinical efficacy. Evidence indicated morphine-evoked neuroinflammation mediated by toll-like receptor 4 (TLR4) - NOD-like receptor protein 3 (NLRP3) inflammasome was important for morphine tolerance. In our study, we investigated whether other existing alternative pathways caused morphine-induced activation of TLR4 in microglia. We focused on heat shock protein 70 (HSP70), a damage-associated molecular pattern (DAMP), which was released from various cells upon stimulations under the control of KATP channel and bound with TLR4-inducing inflammation. Glibenclamide, a classic KATP channel blocker, can improve neuroinflammation by inhibiting the activation of NLRP3 inflammasome. Our present study investigated the effect and possible mechanism of glibenclamide in improving morphine tolerance via its specific inhibition on the release of HSP70 and activation of NLRP3 inflammasome induced by morphine. CD-1 mice were used for tail-flick test to evaluate morphine tolerance. The microglial cell line BV-2 and neural cell line SH-SY5Y were used to investigate the pharmacological effects and the mechanism of glibenclamide on morphine-induced neuroinflammation. The activation of microglia was accessed by immunofluorescence staining. Neuroinflammation-related cytokines were measured by western blot and real-time PCR. The level of HSP70 and related signaling pathway were evaluated by western blot and immunofluorescence staining. Morphine induced the release of HSP70 from neurons. The released HSP70 activated microglia and triggered TLR4-mediated inflammatory response, leading to the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) p65 and the activation of NLRP3 inflammasome. Moreover, anti-HSP70 neutralizing antibody partly attenuated chronic morphine tolerance. The secretion of HSP70 was under the control of MOR/AKT/KATP/ERK signal pathway. Glibenclamide as a classic KATP channel blocker markedly inhibited the release of HSP70 induced by morphine and suppressed HSP70-TLR4-NLRP3 inflammasome-mediated neuroinflammation, which consequently attenuated morphine tolerance. Our study indicated that morphine-induced extracellular HSP70 was an alternative way for the activation of TLR4-NLRP3 in analgesic tolerance. The release of HSP70 was regulated by MOR/AKT/KATP/ERK pathway. Our study suggested a promising target, KATP channel and a new leading compound, glibenclamide, for treating morphine tolerance.
58 citations
Cites background from "Fibroblast growth factors, their re..."
...Previous studies noted out that HSP70, as an important DAMP, was released from intact human prostate carcinoma cell lines (PC-3 and LNCaP) by a mechanism independent of de novo HSP70 synthesis or cell death [30, 31]....
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TL;DR: A review of the relevant roles of FGF21 in metabolism is presented and it is shown that its administration to diabetic rodents and monkeys lowers blood glucose and triglyceride levels.
Abstract: FGF21 is a novel member of the FGFs family, is mainly expressed in liver and it functions as a potent activator of glucose uptake on adipocytes. When over expressed in transgenic mice, it protects animals from diet-induced obesity and its administration to diabetic rodents and monkeys lowers blood glucose and triglyceride levels. Recently, increased levels of FGF21 have been identified as an independent risk factor related with metabolic syndrome. A review of the relevant roles of FGF21 in metabolism is presented here.
58 citations
Cites background from "Fibroblast growth factors, their re..."
...FGFs are usually involved in cellular growth, angiogenesis and wound repair [1, 2]....
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TL;DR: Interestingly, FGF23 induces phospholipase Cγ activity in primary hippocampal neurons and enhances the synaptic density in a FGF‐receptor (FGF‐R) dependent manner, compared with other FGFs.
Abstract: Endocrine fibroblast growth factor 23 (FGF23) is predominantly secreted by osteocytes and facilitates renal phosphate excretion. However, FGF23 is also present in cerebrospinal fluid. In chronic kidney disease, FGF23 serum levels are excessively elevated and associated with learning and memory deficits. Structural plasticity of the hippocampus such as formation of new synapses or an altered dendritic arborization comprises a cellular and morphological correlate of memory formation. Therefore, we hypothesize that FGF23 alters hippocampal neuron morphology and synapses. To address this, we prepared primary murine hippocampal cultures and incubated them with recombinant FGF23 alone or together with a soluble isoform of its co-receptor α-Klotho. Neuronal expression of a fluorescent reporter allowed for a detailed evaluation of the neuronal morphology by Sholl analysis. Additionally, we evaluated synaptic density, identified by stainings, for synaptic markers. We show an enhanced number of primary neurites combined with a reduced arborization, resulting in a less complex morphology of neurons treated with FGF23. Moreover, FGF23 enhances the synaptic density in a FGF-receptor (FGF-R) dependent manner. Finally, we addressed the corresponding signaling events downstream of FGF-R employing a combination of western blots and quantitative immunofluorescence. Interestingly, FGF23 induces phospholipase Cγ activity in primary hippocampal neurons. Co-application of soluble α-Klotho leads to activation of the Akt-pathway and modifies FGF23-impact on neuronal morphology and synaptic density. Compared with other FGFs, this alternative signaling pattern is a possible reason for differential effects of FGF23 on hippocampal neurons and may thereby contribute to learning and memory deficits in chronic kidney disease patients. In this study, we show that fibroblast growth factor 23 inhibits neuronal ramification and enhances the synaptic density in primary hippocampal cultures accompanied by phospholipase Cγ-activation. Co-application of the co-receptor α-Klotho leads to an Akt-activation and further modifies neuronal morphology and number of synapses. Those effects provide a mechanistic basis for memory deficits in patients suffering from chronic kidney disease (CKD) characterized by excessively elevated FGF23 levels as well as memory deficits.
57 citations
TL;DR: A spatial/temporal map of the signaling pathways active in the postnatal intervertebral disc during growth, differentiation, and aging of the disc is presented.
Abstract: STUDY DESIGN Intervertebral discs at different postnatal ages were assessed for active intercellular signaling pathways. OBJECTIVE To generate a spatial and temporal map of the signaling pathways active in the postnatal intervertebral disc (IVD). SUMMARY OF BACKGROUND DATA The postnatal IVD is a complex structure, consisting of 3 histologically distinct components, the nucleus pulposus, fibrous anulus fibrosus, and endplate. These differentiate and grow during the first 9 weeks of age in the mouse. Identification of the major signaling pathways active during and after the growth and differentiation period will allow functional analysis using mouse genetics and identify targets for therapy for individual components of the disc. METHODS Antibodies specific for individual cell signaling pathways were used on cryostat sections of IVD at different postnatal ages to identify which components of the IVD were responding to major classes of intercellular signal, including sonic hedgehog, Wnt, TGFbeta, FGF, and BMPs. RESULTS We present a spatial/temporal map of these signaling pathways during growth, differentiation, and aging of the disc. CONCLUSION During growth and differentiation of the disc, its different components respond at different times to different intercellular signaling ligands. Most of these are dramatically downregulated at the end of disc growth.
57 citations
57 citations
References
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TL;DR: It is demonstrated that free heparin and heparan sulfate can reconstitute a low affinity receptor that is, in turn, required for the high affinity binding of bFGF.
2,448 citations
TL;DR: This work highlights conserved protein domains that act as key regulatory participants in many of these different signalling pathways in multicellular organisms.
Abstract: Communication between cells assumes particular importance in multicellular organisms. The growth, migration and differentiation of cells in the embryo, and their organization into specific tissues, depend on signals transmitted from one cell to another. In the adult, cell signalling orchestrates normal cellular behaviour and responses to wounding and infection. The consequences of breakdowns in this signalling underlie cancer, diabetes and disorders of the immune and cardiovascular systems. Conserved protein domains that act as key regulatory participants in many of these different signalling pathways are highlighted.
2,433 citations
"Fibroblast growth factors, their re..." refers background in this paper
...One way these recruited target proteins may be localized to the activated receptor is through the interaction between their Src-homology 2 (SH2) domains and specific phosphotyrosine residues on the activated receptor (Pawson 1995)....
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...Phosphorylated tyrosine residues, in turn, recruit other signaling molecules to the activated receptors and propagate the signal through many possible transduction pathways (Pawson 1995)....
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TL;DR: Electron microscopic examination of the corneal neovascularization of thalidomide-treated rabbits revealed specific ultrastructural changes similar to those seen in the deformed limb bud vasculature of Thalidomid-treated embryos.
Abstract: Thalidomide is a potent teratogen causing dysmelia (stunted limb growth) in humans. We have demonstrated that orally administered thalidomide is an inhibitor of angiogenesis induced by basic fibroblast growth factor in a rabbit cornea micropocket assay. Experiments including the analysis of thalidomide analogs revealed that the antiangiogenic activity correlated with the teratogenicity but not with the sedative or the mild immunosuppressive properties of thalidomide. Electron microscopic examination of the corneal neovascularization of thalidomide-treated rabbits revealed specific ultrastructural changes similar to those seen in the deformed limb bud vasculature of thalidomide-treated embryos. These experiments shed light on the mechanism of thalidomide's teratogenicity and hold promise for the potential use of thalidomide as an orally administered drug for the treatment of many diverse diseases dependent on angiogenesis.
2,364 citations
TL;DR: It is demonstrated that FGF 1 is the only FGF that can activate all FGF receptor splice variants and the relative activity of all the other members of the FGF family is determined.
2,066 citations
"Fibroblast growth factors, their re..." refers background in this paper
...†From Ornitz et al. (1996), except where stated; ‡From Koga et al. (1995); §From Miralles et al. (1999); ¶From Xu et al. (1999). topologically identical to interleukin-1β (IL-1β) (Zhu et al. 1991), with which some members also share the feature of secretion by an endoplasmic reticulum…...
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...Mutation of all four cysteines to serines results in a protein with the same secondary structure and equally mitogenic for 3T3 cells as the wild-type FGF-2 (Foxet al. 1988), suggesting that the formation of disulfide bridges is not important for the secondary structure and mitogenic activity of…...
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...Ornitz et al. (1996) determined the specificity of different FGFs for different receptor isoforms by overexpressing these isoforms in Baf3 cells, which do not normally express FGFRs, and assaying for [3H]thymidine incorporation in these cells following treatment with different FGFs (see Table 2)....
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...1, IIIb 100 60 34 16 4 5 6 4 4 1, IIIc 100 104 0 102 59 55 0 1 21 2, IIIb 100 9 45 15 5 5 81 4 7 2, IIIc 100 64 4 94 25 61 2.5 16 89 3, IIIb 100 1 2 1 1 1 1 1 42 3, IIIc 100 107 1 69 12 9 1 41 96 4 100 113 6 108 7 79 2 76 75 Modified from Ornitz et al. (1996)....
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1,994 citations
"Fibroblast growth factors, their re..." refers background in this paper
...Defining features of the FGF family are a strong affinity for heparin and HLGAGs (Burgess & Maciag 1989), as well as a central core of 140 amino acids that is highly homologous between different family members....
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