ABSTRACT
The fibroblast growth factor receptor (FGFR) plays a vital role in the development of the nervous system regulating a multitude of cellular processes. One of the interaction partners of the FGFR is the neural cell adhesion molecule (NCAM), which is known to play an important role in neuronal development, regeneration and synaptic plasticity. Thus, simultaneous activation of FGFR- and NCAM-mediated signaling pathways may be expected to affect processes underlying neurodegenerative diseases. We here report the identification of a peptide compound, Enreptin, capable of interacting with both FGFR and NCAM. We demonstrate that this dual specificity agonist induces phosphorylation of FGFR and differentiation and survival of primary neurons in vitro, and that these effects are inhibited by abrogation of both NCAM and FGFR signaling pathways. Furthermore, Enreptin crosses the blood-brain barrier after subcutaneous administration, enhances long-term memory in normal mice and ameliorates memory deficit in mice with induced brain inflammation. Moreover, Enreptin reduces cognitive impairment and neuronal death induced by Aß25-35 in a rat model of Alzheimer's disease, and reduces the mortality rate and clinical signs of experimental autoimmune encephalomyelitis in rats. Thus, Enreptin is an attractive candidate for the treatment of neurological diseases.
Subject(s)
Memory/drug effects , Neural Cell Adhesion Molecules/agonists , Neurons/drug effects , Neuroprotective Agents/pharmacology , Oligopeptides/pharmacology , Receptors, Fibroblast Growth Factor/agonists , Animals , Behavior, Animal/drug effects , Brain Diseases/pathology , Cell Differentiation/drug effects , Cells, Cultured , Cognition Disorders/pathology , Disease Models, Animal , Humans , Male , Mice , Mice, Inbred BALB C , Neurons/cytology , Rats , Rats, Wistar , Surface Plasmon ResonanceABSTRACT
Basic fibroblast growth factor (FGF2, bFGF) is the most extensively studied member of the FGF family and is involved in neurogenesis, differentiation, neuroprotection, and synaptic plasticity in the CNS. FGF2 executes its pleiotropic biologic actions by binding, dimerizing, and activating FGF receptors (FGFRs). The present study reports the physiologic impact of various FGF2-FGFR1 contact sites employing three different synthetic peptides, termed canofins, designed based on structural analysis of the interactions between FGF2 and FGFR1. Canofins mimic the cognate ligand interaction with the receptor and preserve the neuritogenic and neuroprotective properties of FGF2. Canofins were shown by surface plasmon resonance analysis to bind to FGFR1 and promote receptor activation. However, FGF2-induced receptor phosphorylation was inhibited by canofins, indicating that canofins are partial FGFR agonists. Furthermore, canofins were demonstrated to induce neuronal differentiation determined by neurite outgrowth from cerebellar granule neurons, and this effect was dependent on FGFR activation. Additionally, canofins acted as neuroprotectants, promoting survival of cerebellar granule neurons induced to undergo apoptosis. Our results suggest that canofins mirror the effect of specific interaction sites in FGF2 for FGFR. Thus, canofins are valuable pharmacological tools to study the functional roles of specific molecular interactions of FGF2 with FGFR.
Subject(s)
Dendrimers/pharmacology , Fibroblast Growth Factor 2/metabolism , Neurons/drug effects , Oligopeptides/pharmacology , Receptor, Fibroblast Growth Factor, Type 1/metabolism , Animals , Apoptosis/drug effects , Cell Differentiation/drug effects , Cell Survival/drug effects , Cells, Cultured , Cerebellum/cytology , Dendrimers/chemistry , Drug Partial Agonism , Fibroblast Growth Factor 2/chemistry , Ligands , Models, Molecular , Neurites/drug effects , Neurites/physiology , Neurons/cytology , Neuroprotective Agents/chemistry , Neuroprotective Agents/pharmacology , Oligopeptides/chemistry , Phosphorylation , Rats , Rats, Wistar , Receptor, Fibroblast Growth Factor, Type 1/agonists , Receptor, Fibroblast Growth Factor, Type 1/chemistry , Surface Plasmon ResonanceABSTRACT
Fibroblast growth factor (FGF) receptor (FGFR) consists extracellularly of three immunoglobulin (Ig) modules (Ig1-3). Currently, there are two competing models (symmetric and asymmetric) of the FGF-FGFR-heparin complex based on crystal structures. Indirect evidence exists in support of both models. However, it is not clear which model is physiologically relevant. Our aim was to obtain direct, non-crystallographic evidence in support of them. We found by nuclear magnetic resonance that Ig2 could bind to FGF1 not only via the primary site (present in both models), but also via the secondary site (present only in the symmetric model). Thus, our data support the symmetric model.
