Investigations into the structure and function of the 18kDa Translocator Protein (TSPO)

The translocator protein (TSPO) is a 5 transmembrane mitochondrial protein involved in regulating cholesterol transport and neurosteroid synthesis. TSPO is being investigated as an in vivo brain imaging and drug treatment target as it is upregulated in neuroglia in both acute and chronic neuroinflammatory conditions including Alzheimer’s disease. Although the functional receptor form is speculated to be a dimer, the effects of pharmacological ligands on dimerisation remain largely unknown. Ligand effects on complex formation of TSPO and its missense variant, A147T, were studied using co-immunoprecipitation, FLIM-FRET and confocal microscopy of cultured cells. Co-immunoprecipitation revealed the spontaneous formation of stable dimers that was disrupted by various TSPO ligands, particularly in the presence of the A147T mutation. In addition, it was demonstrated that the deletion of the cholesterol-recognition amino acid consensus sequence at the extreme carboxyl-terminus of TSPO affects homodimerisation. Deletion of the N-terminus had no discernable effect on homodimerisation, but confocal microscopy revealed mitochondrial dysfunctions that were also reflected in gene expression changes of proteins involved in mitochondrial fission and fusion. Novel TSPO ligands were also screened for binding affinities to identify potential leads for future investigations into the effects of ligands on the TSPO dimer and for development as therapeutics

The polyphenol altenusin inhibits in vitro fibrillization of tau and reduces induced tau pathology in primary neurons

In Alzheimer’s disease, the microtubule-associated protein tau forms intracellular neurofibrillary tangles (NFTs). A critical step in the formation of NFTs is the conversion of soluble tau into insoluble filaments. Accordingly, a current therapeutic strategy in clinical trials is aimed at preventing tau aggregation. Here, we assessed altenusin, a bioactive polyphenolic compound, for its potential to inhibit tau aggregation. Altenusin inhibits aggregation of tau protein into paired helical filaments in vitro. This was associated with stabilization of tau dimers and other oligomers into globular structures as revealed by atomic force microscopy. Moreover, altenusin reduced tau phosphorylation in cells expressing pathogenic tau, and prevented neuritic tau pathology induced by incubation of primary neurons with tau fibrils. However, treatment of tau transgenic mice did not improve neuropathology and functional deficits. Taken together, altenusin prevents tau fibrillization in vitro and induced tau pathology in neurons.This work has been funded by the National Health & Medical Research Council (NH&MRC 1037746, 1020562, 1083209) and the Australian Research Council (ARC 130102027) to L.M.I. A.C. was supported by Postdoctoral Fellowship CONICYT (74140034). L.M.I. is an NH&MRC Senior Research Fellow.Peer Reviewe

The Polyphenol Altenusin Inhibits in Vitro Fibrillization of Tau and Reduces Induced Tau Pathology in Primary Neurons

In Alzheimer’s disease, the microtubule-associated protein tau forms intracellular neurofibrillary tangles (NFTs). A critical step in the formation of NFTs is the conversion of soluble tau into insoluble filaments. Accordingly, a current therapeutic strategy in clinical trials is aimed at preventing tau aggregation. Here, we assessed altenusin, a bioactive polyphenolic compound, for its potential to inhibit tau aggregation. Altenusin inhibits aggregation of tau protein into paired helical filaments in vitro. This was associated with stabilization of tau dimers and other oligomers into globular structures as revealed by atomic force microscopy. Moreover, altenusin reduced tau phosphorylation in cells expressing pathogenic tau, and prevented neuritic tau pathology induced by incubation of primary neurons with tau fibrils. However, treatment of tau transgenic mice did not improve neuropathology and functional deficits. Taken together, altenusin prevents tau fibrillization in vitro and induced tau pathology in neurons

First Demonstration of Positive Allosteric-like Modulation at the Human Wild Type Translocator Protein (TSPO)

We show that changing the number and position of nitrogen atoms in the heteroatomic core of a pyrazolopyrimidine acetamide is sufficient to induce complex binding to wild type human TSPO. Only compounds with this complex binding profile lacked intrinsic effect on glioblastoma proliferation but positively modulated the antiproliferative effects of a synthetic TSPO ligand. To the best of our knowledge this is the first demonstration of allosteric-like interaction at the wild type human TSPO

Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons

The culturing of primary neurons represents a central pillar of neuroscience research. Primary neurons are derived directly from brain tissue and recapitulate key aspects of neuronal development in an in vitro setting. Unlike neural stem cells, primary neurons do not divide; thus, initial attachment of cells to a suitable substrate is critical. Commonly used polylysine substrates can suffer from batch variability owing to their polymeric nature. Herein, we report the use of chemically well-defined, self-assembling tetrapeptides as substrates for primary neuronal culture. These water-soluble peptides assemble into fibers which facilitate adhesion and development of primary neurons, their long-term survival (>40 days), synaptic maturation, and electrical activity. Furthermore, these substrates are permissive toward neuronal transfection and transduction which, coupled with their uniformity and reproducible nature, make them suitable for a wide variety of applications in neuroscience

Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons

The culturing of primary neurons represents a central pillar of neuroscience research. Primary neurons are derived directly from brain tissue and recapitulate key aspects of neuronal development in an in vitro setting. Unlike neural stem cells, primary neurons do not divide; thus, initial attachment of cells to a suitable substrate is critical. Commonly used polylysine substrates can suffer from batch variability owing to their polymeric nature. Herein, we report the use of chemically well-defined, self-assembling tetrapeptides as substrates for primary neuronal culture. These water-soluble peptides assemble into fibers which facilitate adhesion and development of primary neurons, their long-term survival (>40 days), synaptic maturation, and electrical activity. Furthermore, these substrates are permissive toward neuronal transfection and transduction which, coupled with their uniformity and reproducible nature, make them suitable for a wide variety of applications in neuroscience

Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons

The culturing of primary neurons represents a central pillar of neuroscience research. Primary neurons are derived directly from brain tissue and recapitulate key aspects of neuronal development in an in vitro setting. Unlike neural stem cells, primary neurons do not divide; thus, initial attachment of cells to a suitable substrate is critical. Commonly used polylysine substrates can suffer from batch variability owing to their polymeric nature. Herein, we report the use of chemically well-defined, self-assembling tetrapeptides as substrates for primary neuronal culture. These water-soluble peptides assemble into fibers which facilitate adhesion and development of primary neurons, their long-term survival (>40 days), synaptic maturation, and electrical activity. Furthermore, these substrates are permissive toward neuronal transfection and transduction which, coupled with their uniformity and reproducible nature, make them suitable for a wide variety of applications in neuroscience

Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons

The culturing of primary neurons represents a central pillar of neuroscience research. Primary neurons are derived directly from brain tissue and recapitulate key aspects of neuronal development in an in vitro setting. Unlike neural stem cells, primary neurons do not divide; thus, initial attachment of cells to a suitable substrate is critical. Commonly used polylysine substrates can suffer from batch variability owing to their polymeric nature. Herein, we report the use of chemically well-defined, self-assembling tetrapeptides as substrates for primary neuronal culture. These water-soluble peptides assemble into fibers which facilitate adhesion and development of primary neurons, their long-term survival (>40 days), synaptic maturation, and electrical activity. Furthermore, these substrates are permissive toward neuronal transfection and transduction which, coupled with their uniformity and reproducible nature, make them suitable for a wide variety of applications in neuroscience

Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons

The culturing of primary neurons represents a central pillar of neuroscience research. Primary neurons are derived directly from brain tissue and recapitulate key aspects of neuronal development in an in vitro setting. Unlike neural stem cells, primary neurons do not divide; thus, initial attachment of cells to a suitable substrate is critical. Commonly used polylysine substrates can suffer from batch variability owing to their polymeric nature. Herein, we report the use of chemically well-defined, self-assembling tetrapeptides as substrates for primary neuronal culture. These water-soluble peptides assemble into fibers which facilitate adhesion and development of primary neurons, their long-term survival (>40 days), synaptic maturation, and electrical activity. Furthermore, these substrates are permissive toward neuronal transfection and transduction which, coupled with their uniformity and reproducible nature, make them suitable for a wide variety of applications in neuroscience