ABSTRACT
Our recent study demonstrated that an amyloid-ß binding molecule, BTA-EG4, increases dendritic spine number via Ras-mediated signaling. To potentially optimize the potency of the BTA compounds, we synthesized and evaluated an amyloid-ß binding analog of BTA-EG4 with increased solubility in aqueous solution, BTA-EG6. We initially examined the effects of BTA-EG6 on dendritic spine formation and found that BTA-EG6-treated primary hippocampal neurons had significantly increased dendritic spine number compared to control treatment. In addition, BTA-EG6 significantly increased the surface level of AMPA receptors. Upon investigation into the molecular mechanism by which BTA-EG6 promotes dendritic spine formation, we found that BTA-EG6 may exert its effects on spinogenesis via RasGRF1-ERK signaling, with potential involvement of other spinogenesis-related proteins such as Cdc42 and CDK5. Taken together, our data suggest that BTA-EG6 boosts spine and synapse number, which may have a beneficial effect of enhancing neuronal and synaptic function in the normal healthy brain.
Subject(s)
Benzothiazoles/chemistry , Benzothiazoles/pharmacology , Dendritic Spines/drug effects , Signal Transduction/drug effects , ras Proteins/metabolism , ras-GRF1/metabolism , Aniline Compounds/chemistry , Aniline Compounds/pharmacology , Animals , Cells, Cultured , Dendritic Spines/metabolism , Dendritic Spines/ultrastructure , Ethylene Glycol/chemistry , Ethylene Glycol/pharmacology , MAP Kinase Signaling System/drug effects , Rats, Sprague-Dawley , Receptors, AMPA/metabolismABSTRACT
The tetra(ethylene glycol) derivative of benzothiazole aniline, BTA-EG4, is a novel amyloid-binding small molecule that can penetrate the blood-brain barrier and protect cells from Aß-induced toxicity. However, the effects of Aß-targeting molecules on other cellular processes, including those that modulate synaptic plasticity, remain unknown. We report here that BTA-EG4 decreases Aß levels, alters cell surface expression of amyloid precursor protein (APP), and improves memory in wild-type mice. Interestingly, the BTA-EG4-mediated behavioral improvement is not correlated with LTP, but with increased spinogenesis. The higher dendritic spine density reflects an increase in the number of functional synapses as determined by increased miniature EPSC (mEPSC) frequency without changes in presynaptic parameters or postsynaptic mEPSC amplitude. Additionally, BTA-EG4 requires APP to regulate dendritic spine density through a Ras signaling-dependent mechanism. Thus, BTA-EG4 may provide broad therapeutic benefits for improving neuronal and cognitive function, and may have implications in neurodegenerative disease therapy.
Subject(s)
Aniline Compounds/pharmacology , Benzothiazoles/pharmacology , Dendritic Spines/drug effects , Ethylene Glycols/pharmacology , Genes, ras/drug effects , Neurogenesis/drug effects , Amyloid beta-Protein Precursor/genetics , Animals , Biotinylation , COS Cells , Cerebrovascular Circulation/drug effects , Chlorocebus aethiops , Cognition Disorders/chemically induced , Cognition Disorders/psychology , Enzyme-Linked Immunosorbent Assay , Excitatory Postsynaptic Potentials/drug effects , Immunohistochemistry , Long-Term Potentiation/physiology , Male , Maze Learning/physiology , Mice , Mice, Inbred C57BL , Mice, Knockout , Neurons/drug effects , Receptors, AMPA/drug effectsABSTRACT
This paper describes the spontaneous formation of well-defined pores in planar lipid bilayers from the self-assembly of a small synthetic molecule that contains a benzothiazole aniline (BTA) group attached to a tetra-ethylene glycol (EG4) moiety. Macroscopic and single-channel current recordings suggest that these pores are formed by the assembly of four BTA-EG4 monomers with an open pore diameter that appears similar to the one of gramicidin pores (~0.4 nm). The single-channel conductance of these pores is modulated by the pH of the electrolyte and has a minimum at pH~3. Self-assembled pores from BTA-EG4 are selective for monovalent cations and have long open channel lifetimes on the order of seconds. BTA-EG4 monomers in these pores appear to be arranged symmetrically across both leaflets of the bilayer, and spectroscopy studies suggest that the fluorescent BTA group is localized inside the lipid bilayers. In terms of biological activity, BTA-EG4 molecules inhibited growth of gram-positive Bacillus subtilis bacteria (IC50~50 µM) and human neuroblastoma SH-SY5Y cells (IC50~60 µM), while they were not toxic to gram-negative Escherichia coli bacteria at a concentration up to 500 µM. Based on these properties, this drug-like, synthetic, pore-forming molecule with a molecular weight below 500 g mol(-1) might be appealing as a starting material for development of antibiotics or membrane-permeating moieties for drug delivery. From a biophysical point of view, long-lived, well-defined ion-selective pores from BTA-EG4 molecules offer an example of a self-assembled synthetic supramolecule with biological function.
Subject(s)
Benzothiazoles/chemistry , Ethylene Glycols/chemistry , Ion Channels/chemistry , Cations , Cell Line, Tumor , Humans , Magnetic Resonance Spectroscopy , Spectrometry, Mass, Electrospray IonizationABSTRACT
Semen was recently shown to contain amyloid fibrils formed from a self-assembling peptide fragment of the protein prostatic acid phosphatase. These amyloid fibrils, termed semen-derived enhancer of virus infection, or SEVI, have been shown to strongly enhance HIV infectivity and may play an important role in sexual transmission of HIV, making them a potential microbicide target. One novel approach to target these fibrils is the use of small molecules known to intercalate into the structure of amyloid fibrils, such as derivatives of thioflavin-T. Here, we show that the amyloid-binding small molecule BTA-EG(6) (the hexa(ethylene glycol) derivative of benzothiazole aniline) is able to bind SEVI fibrils and effectively inhibit both SEVI-mediated and semen-mediated enhancement of HIV infection. BTA-EG(6) also blocks the interactions of SEVI with HIV-1 virions and HIV-1 target cells but does not cause any inflammation or toxicity to cervical epithelial cells. These results suggest that an amyloid-binding small molecule may have utility as a microbicide, or microbicidal supplement, for HIV-1.
Subject(s)
Amyloid/metabolism , Benzothiazoles/pharmacology , HIV-1/drug effects , Semen/metabolism , Animals , Benzothiazoles/chemistry , Benzothiazoles/metabolism , Cell Line, Tumor , Cells, Cultured , Competitive Bidding , Dose-Response Relationship, Drug , Flow Cytometry , HIV-1/physiology , Humans , Jurkat Cells , Kinetics , Male , Molecular Structure , Protein Binding , Thiazoles/chemistry , Virion/metabolism , Virus Attachment/drug effectsABSTRACT
A general method for synthesizing alpha-hydroxy N-acylindoles in one-pot via an acid-catalyzed condensation of a convertible isonitrile with water and various aldehydes is presented. These intermediates were incorporated into poly(alpha-hydroxy acid) copolymers bearing residues with functionalizable side chains, which could be further modified through Cu(I)-catalyzed azide-alkyne cylcoaddition reactions. This versatile synthetic strategy provides access to side chain functionalized poly(alpha-hydroxy acid) copolymers from readily available aldehydes, making it potentially useful as an approach to synthesize biodegradable polymers with new, tunable properties.