8-(trifluoromethyl)-1-2-3-4-5-benzopentathiepin-6-amine and Cognition-Disorders

Brain-derived neurotrophic factor (BDNF) and STriatal-Enriched protein tyrosine Phosphatase 61 (STEP61) have opposing functions in the brain, with BDNF supporting and STEP61 opposing synaptic strengthening. BDNF and STEP61 also exhibit an inverse pattern of expression in a number of brain disorders, including schizophrenia (SZ). NMDAR antagonists such as phencyclidine (PCP) elicit SZ-like symptoms in rodent models and unaffected individuals, and exacerbate psychotic episodes in SZ. Here we characterize the regulation of BDNF expression by STEP61, utilizing PCP-treated cortical culture and PCP-treated mice. PCP-treated cortical neurons showed both an increase in STEP61 levels and a decrease in BDNF expression. The reduction in BDNF expression was prevented by STEP61 knockdown or use of the STEP inhibitor, TC-2153. The PCP-induced increase in STEP61 expression was associated with the inhibition of CREB-dependent BDNF transcription. Similarly, both genetic and pharmacologic inhibition of STEP prevented the PCP-induced reduction in BDNF expression in vivo and normalized PCP-induced hyperlocomotion and cognitive deficits. These results suggest a mechanism by which STEP61 regulates BDNF expression, with implications for cognitive functioning in CNS disorders.

Topics: Animals; Benzothiepins; Brain-Derived Neurotrophic Factor; Cells, Cultured; Cognition Disorders; CREB-Binding Protein; Down-Regulation; Male; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Motor Activity; Neurons; Phencyclidine; Phosphorylation; Protein Tyrosine Phosphatases; Receptors, N-Methyl-D-Aspartate; RNA Interference; Ubiquitination

STEP (STriatal-Enriched protein tyrosine Phosphatase) is a neuron-specific phosphatase that regulates N-methyl-D-aspartate receptor (NMDAR) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) trafficking, as well as ERK1/2, p38, Fyn, and Pyk2 activity. STEP is overactive in several neuropsychiatric and neurodegenerative disorders, including Alzheimer's disease (AD). The increase in STEP activity likely disrupts synaptic function and contributes to the cognitive deficits in AD. AD mice lacking STEP have restored levels of glutamate receptors on synaptosomal membranes and improved cognitive function, results that suggest STEP as a novel therapeutic target for AD. Here we describe the first large-scale effort to identify and characterize small-molecule STEP inhibitors. We identified the benzopentathiepin 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (known as TC-2153) as an inhibitor of STEP with an IC50 of 24.6 nM. TC-2153 represents a novel class of PTP inhibitors based upon a cyclic polysulfide pharmacophore that forms a reversible covalent bond with the catalytic cysteine in STEP. In cell-based secondary assays, TC-2153 increased tyrosine phosphorylation of STEP substrates ERK1/2, Pyk2, and GluN2B, and exhibited no toxicity in cortical cultures. Validation and specificity experiments performed in wild-type (WT) and STEP knockout (KO) cortical cells and in vivo in WT and STEP KO mice suggest specificity of inhibitors towards STEP compared to highly homologous tyrosine phosphatases. Furthermore, TC-2153 improved cognitive function in several cognitive tasks in 6- and 12-mo-old triple transgenic AD (3xTg-AD) mice, with no change in beta amyloid and phospho-tau levels.

Topics: Alzheimer Disease; Amino Acid Sequence; Animals; Benzothiepins; Catalytic Domain; Cell Death; Cerebral Cortex; Cognition Disorders; Cysteine; Disease Models, Animal; Enzyme Inhibitors; High-Throughput Screening Assays; Humans; Male; Mice, Inbred C57BL; Mice, Knockout; Molecular Sequence Data; Neurons; Phosphorylation; Phosphotyrosine; Protein Tyrosine Phosphatases, Non-Receptor; Substrate Specificity

Topics: Animals; Benzothiepins; Cognition Disorders; Enzyme Inhibitors; High-Throughput Screening Assays; Humans; Mice; Phosphorylation; Protein Tyrosine Phosphatases, Non-Receptor