The family of calcium binding proteins called KChIPs associates with Kv4 family K(+) channels and modulates their biophysical properties. Here, using mutagenesis and X-ray crystallography, we explore the interaction between Kv4 subunits and KChIP1. Two regions in the Kv4.2 N terminus, residues 7-11 and 71-90, are necessary for KChIP1 modulation and interaction with Kv4.2. When inserted into the Kv1.2 N terminus, residues 71-90 of Kv4.2 are also sufficient to confer association with KChIP1. To provide a structural framework for these data, we solved the crystal structures of Kv4.3N and KChIP1 individually. Taken together with the mutagenesis data, the individual structures suggest that that the Kv4 N terminus is required for stable association with KChIP1, perhaps through a hydrophobic surface interaction, and that residues 71-90 in Kv4 subunits form a contact loop that mediates the specific association of KChIPs with Kv4 subunits.

Rapamycin is an immunosuppressive immunophilin ligand reported as having neurotrophic activity. We show that modification of rapamycin at the mammalian target of rapamycin (mTOR) binding region yields immunophilin ligands, WYE-592 and ILS-920, with potent neurotrophic activities in cortical neuronal cultures, efficacy in a rodent model for ischemic stroke, and significantly reduced immunosuppressive activity. Surprisingly, both compounds showed higher binding selectivity for FKBP52 versus FKBP12, in contrast to previously reported immunophilin ligands. Affinity purification revealed two key binding proteins, the immunophilin FKBP52 and the ␤1-subunit of L-type voltage-dependent Ca 2؉ channels (CACNB1). Electrophysiological analysis indicated that both compounds can inhibit L-type Ca 2؉ channels in rat hippocampal neurons and F-11 dorsal root ganglia (DRG)/neuroblastoma cells. We propose that these immunophilin ligands can protect neurons from Ca 2؉ -induced cell death by modulating Ca 2؉ channels and promote neurite outgrowth via FKBP52 binding.immunophilin ͉ L-type voltage-gated calcium channel ͉ natural products ͉ neurodegeneration ͉ stroke

The ␣7 nicotinic acetylcholine receptor (nAChR) has been implicated in Alzheimer's disease and schizophrenia, leading to efforts targeted toward discovering agonists and positive allosteric modulators (PAMs) of this receptor. In a Ca 2ϩ flux fluorometric imaging plate reader assay, SB-206553 (3,5-dihydro -5 -methyl -N -3 -pyridinylbenzo [1, 2 -b : 4, 5 -bЈ] -di pyrrole-1(2H)-carboxamide), a compound known as a 5-hydroxytryptamine 2B/2C receptor antagonist, produced an 8-fold potentiation of the evoked calcium signal in the presence of an EC 20 concentration of nicotine and a corresponding EC 50 of 1.5 M for potentiation of EC 20 nicotine responses in GH4C1 cells expressing the ␣7 receptor. SB-206553 was devoid of direct ␣7 receptor agonist activity and selective against other nicotinic receptors. Confirmation of the PAM activity of SB-206553 on the ␣7 nAChR was obtained in patch-clamp electrophysiological experiments in GH4C1 cells, where it failed to evoke any detectable currents when applied alone, yet dramatically potentiated the currents evoked by an EC 20 (17 M) and EC 100 (124 M) of acetylcholine (ACh). Native nicotinic receptors in CA1 stratum radiatum interneurons of rat hippocampal slices could also be activated by ACh (200 M), an effect that was entirely blocked by the ␣7-selective antagonist methyllycaconitine (MLA). These ACh currents were potentiated by SB-206553, which increased the area of the current response significantly, resulting in a 40-fold enhancement at 100 M. In behavioral experiments in rats, SB-206553 reversed an MK-801 (dizocilpine maleate)-induced deficit in the prepulse inhibition of acoustic startle response, an effect attenuated in the presence of MLA. This latter observation provides further evidence in support of the potential therapeutic utility of ␣7 nAChR PAMs in schizophrenia.Nicotinic acetylcholine receptors (nAChRs) are formed of pentameric combinations of ␣ and non-␣ subunits with a high degree of complexity conferred by 10 different ␣ subunits (␣1-␣10) and seven different non-␣ subunits (␤1-␤4, ␥␦, ε)Article, publication date, and citation information can be found at

These findings demonstrate that ASIC inhibition produces anxiolytic-like effects in some behavioral models and indicate a potential role for GABAergic mechanisms to underlie these anxiolytic-like effects.

Alpha-7 nicotinic acetylcholine receptor (alpha7 nAChR) agonists are promising therapeutic candidates for the treatment of cognitive impairment. We report a series of novel, potent small molecule agonists (4-18) of the alpha7 nAChR deriving from our continuing efforts in the areas of Alzheimer's disease and schizophrenia. One of the compounds of the series containing a urea moiety (16) was further shown to be a selective agonist of the alpha7 nAChR with excellent in vitro and in vivo profiles, brain penetration, and oral bioavailability and demonstrated in vivo efficacy in multiple behavioral cognition models. Structural modifications leading to the improved selectivity profile and the biological evaluation of this series of compounds are discussed.