Human Hsp70 Substrate-Binding Domains Recognize Distinct Client Proteins

The 13 Hsp70 proteins in humans act on unique sets of substrates with diversity often being attributed to J-domain-containing protein (Hsp40 or JDP) cofactors. We were therefore surprised to find drastically different binding affinities for Hsp70-peptide substrates, leading us to probe substrate specificity among the 8 canonical Hsp70s from humans. We used peptide arrays to characterize Hsp70 binding and then mined these data using machine learning to develop an algorithm for isoform-specific prediction of Hsp70 binding sequences. The results of this algorithm revealed recognition patterns not predicted based on local sequence alignments. We then showed that none of the human isoforms can complement heat-shocked DnaK knockout Escherichia coli cells. However, chimeric Hsp70s consisting of the human nucleotide-binding domain and the substrate-binding domain of DnaK complement during heat shock, providing further evidence in vivo of the divergent function of the Hsp70 substrate-binding domains. We also demonstrated that the differences in heat shock complementation among the chimeras are not due to loss of DnaJ binding. Although we do not exclude JDPs as additional specificity factors, our data demonstrate substrate specificity among the Hsp70s, which has important implications for inhibitor development in cancer and neurodegeneration.

A peptidomimetic modulator of the CaV2.2 N-type calcium channel for chronic pain

Transmembrane Cav2.2 (N-type) voltage-gated calcium channels are genetically and pharmacologically validated, clinically relevant pain targets. Clinical block of Cav2.2 (e.g., with Prialt/Ziconotide) or indirect modulation [e.g., with gabapentinoids such as Gabapentin (GBP)] mitigates chronic pain but is encumbered by side effects and abuse liability. The cytosolic auxiliary subunit collapsin response mediator protein 2 (CRMP2) targets Cav2.2 to the sensory neuron membrane and regulates their function via an intrinsically disordered motif. A CRMP2-derived peptide (CBD3) uncouples the Cav2.2-CRMP2 interaction to inhibit calcium influx, transmitter release, and pain. We developed and applied a molecular dynamics approach to identify the A1R2 dipeptide in CBD3 as the anchoring Cav2.2 motif and designed pharmacophore models to screen 27 million compounds on the open-access server ZincPharmer. Of 200 curated hits, 77 compounds were assessed using depolarization-evoked calcium influx in rat dorsal root ganglion neurons. Nine small molecules were tested electrophysiologically, while one (CBD3063) was also evaluated biochemically and behaviorally. CBD3063 uncoupled Cav2.2 from CRMP2, reduced membrane Cav2.2 expression and Ca2+ currents, decreased neurotransmission, reduced fiber photometry-based calcium responses in response to mechanical stimulation, and reversed neuropathic and inflammatory pain across sexes in two different species without changes in sensory, sedative, depressive, and cognitive behaviors. CBD3063 is a selective, first-in-class, CRMP2-based peptidomimetic small molecule, which allosterically regulates Cav2.2 to achieve analgesia and pain relief without negative side effect profiles. In summary, CBD3063 could potentially be a more effective alternative to GBP for pain relief.

Identification and targeting of a unique NaV1.7 domain driving chronic pain

Small molecules directly targeting the voltage-gated sodium channel (VGSC) NaV1.7 have not been clinically successful. We reported that preventing the addition of a small ubiquitin-like modifier onto the NaV1.7-interacting cytosolic collapsin response mediator protein 2 (CRMP2) blocked NaV1.7 function and was antinociceptive in rodent models of neuropathic pain. Here, we discovered a CRMP2 regulatory sequence (CRS) unique to NaV1.7 that is essential for this regulatory coupling. CRMP2 preferentially bound to the NaV1.7 CRS over other NaV isoforms. Substitution of the NaV1.7 CRS with the homologous domains from the other eight VGSC isoforms decreased NaV1.7 currents. A cell-penetrant decoy peptide corresponding to the NaV1.7-CRS reduced NaV1.7 currents and trafficking, decreased presynaptic NaV1.7 expression, reduced spinal CGRP release, and reversed nerve injury-induced mechanical allodynia. Importantly, the NaV1.7-CRS peptide did not produce motor impairment, nor did it alter physiological pain sensation, which is essential for survival. As a proof-of-concept for a NaV1.7 -targeted gene therapy, we packaged a plasmid encoding the NaV1.7-CRS in an AAV virus. Treatment with this virus reduced NaV1.7 function in both rodent and rhesus macaque sensory neurons. This gene therapy reversed and prevented mechanical allodynia in a model of nerve injury and reversed mechanical and cold allodynia in a model of chemotherapy-induced peripheral neuropathy. These findings support the conclusion that the CRS domain is a targetable region for the treatment of chronic neuropathic pain.

Generation of an iPSC line from a Pontocerebellar Hypoplasia 1B patient harboring a homozygous c.395 A > C mutation in EXOSC3 along with a family matched control

Pontocerebellar Hypoplasia 1B (PCH1B) is a severe autosomal recessive neurological disorder that is associated with mutations in the exosome complex component RRP40 (EXOSC3) gene. We generated and characterized an iPSC line from an individual with PCH1B that harbors a recessive homozygous c.395 A > C mutation in EXOSC3 and a family matched control from the probands unaffected mother. Each iPSC line presents with normal morphology and karyotype and express high levels of pluripotent markers. UAZTi009-A and UAZTi011-A are capable of directed differentiation and can be used as a vital experimental tool to study the development of PCH1B.

Heat shock protein Grp78/BiP/HspA5 binds directly to TDP-43 and mitigates toxicity associated with disease pathology

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with no cure or effective treatment in which TAR DNA Binding Protein of 43 kDa (TDP-43) abnormally accumulates into misfolded protein aggregates in affected neurons. It is widely accepted that protein misfolding and aggregation promotes proteotoxic stress. The molecular chaperones are a primary line of defense against proteotoxic stress, and there has been long-standing interest in understanding the relationship between chaperones and aggregated protein in ALS. Of particular interest are the heat shock protein of 70 kDa (Hsp70) family of chaperones. However, defining which of the 13 human Hsp70 isoforms is critical for ALS has presented many challenges. To gain insight into the specific Hsp70 that modulates TDP-43, we investigated the relationship between TDP-43 and the Hsp70s using proximity-dependent biotin identification (BioID) and discovered several Hsp70 isoforms associated with TDP-43 in the nucleus, raising the possibility of an interaction with native TDP-43. We further found that HspA5 bound specifically to the RNA-binding domain of TDP-43 using recombinantly expressed proteins. Moreover, in a Drosophila strain that mimics ALS upon TDP-43 expression, the mRNA levels of the HspA5 homologue (Hsc70.3) were significantly increased. Similarly we observed upregulation of HspA5 in prefrontal cortex neurons from human ALS patients. Finally, overexpression of HspA5 in Drosophila rescued TDP-43-induced toxicity, suggesting that upregulation of HspA5 may have a compensatory role in ALS pathobiology.

Aptamers Targeting Hallmark Proteins of Neurodegeneration

Neurodegeneration is a progressive deterioration of neural structures leading to cognitive or motor impairment of the affected patient. There is still no effective therapy for any of the most common neurodegenerative diseases (NDs) such as Alzheimer's or Parkinson's disease. Although NDs exhibit distinct clinical characteristics, many are characterized by the accumulation of misfolded proteins or peptide fragments in the brain and/or spinal cord. The presence of similar inclusion bodies in patients with diverse NDs provides a rationale for developing therapies directed at overlapping disease mechanisms. A novel targeting strategy involves the use of aptamers for therapeutic development. Aptamers are short nucleic acid ligands able to recognize molecular targets with high specificity and high affinity. Despite the fact that several academic groups have shown that aptamers have the potential to be used in therapeutic and diagnostic applications, their clinical translation is still limited. In this study, we describe aptamers that have been developed against proteins relevant to NDs, including prion protein and amyloid beta (Aβ), cell surface receptors and other cytoplasmic proteins. This review also describes advances in the application of these aptamers in imaging, protein detection, and protein quantification, and it provides insights about their accelerated clinical use for disease diagnosis and therapy.

Animal Models of Neurodegenerative Disease: Recent Advances in Fly Highlight Innovative Approaches to Drug Discovery

Neurodegenerative diseases represent a formidable challenge to global health. As advances in other areas of medicine grant healthy living into later decades of life, aging diseases such as Alzheimer's disease (AD) and other neurodegenerative disorders can diminish the quality of these additional years, owed largely to the lack of efficacious treatments and the absence of durable cures. Alzheimer's disease prevalence is predicted to more than double in the next 30 years, affecting nearly 15 million Americans, with AD-associated costs exceeding $1 billion by 2050. Delaying onset of AD and other neurodegenerative diseases is critical to improving the quality of life for patients and reducing the burden of disease on caregivers and healthcare systems. Significant progress has been made to model disease pathogenesis and identify points of therapeutic intervention. While some researchers have contributed to our understanding of the proteins and pathways that drive biological dysfunction in disease using in vitro and in vivo models, others have provided mathematical, biophysical, and computational technologies to identify potential therapeutic compounds using in silico modeling. The most exciting phase of the drug discovery process is now: by applying a target-directed approach that leverages the strengths of multiple techniques and validates lead hits using Drosophila as an animal model of disease, we are on the fast-track to identifying novel therapeutics to restore health to those impacted by neurodegenerative disease.

Selective targeting of NaV1.7 via inhibition of the CRMP2-Ubc9 interaction reduces pain in rodents

The voltage-gated sodium NaV1.7 channel, critical for sensing pain, has been actively targeted by drug developers; however, there are currently no effective and safe therapies targeting NaV1.7. Here, we tested whether a different approach, indirect NaV1.7 regulation, could have antinociceptive effects in preclinical models. We found that preventing addition of small ubiquitin-like modifier (SUMO) on the NaV1.7-interacting cytosolic collapsin response mediator protein 2 (CRMP2) blocked NaV1.7 functions and had antinociceptive effects in rodents. In silico targeting of the SUMOylation site in CRMP2 (Lys374) identified >200 hits, of which compound 194 exhibited selective in vitro and ex vivo NaV1.7 engagement. Orally administered 194 was not only antinociceptive in preclinical models of acute and chronic pain but also demonstrated synergy alongside other analgesics—without eliciting addiction, rewarding properties, or neurotoxicity. Analgesia conferred by 194 was opioid receptor dependent. Our results demonstrate that 194 is a first-in-class protein-protein inhibitor that capitalizes on CRMP2-NaV1.7 regulation to deliver safe analgesia in rodents.

Antihypertensive drug treatment and susceptibility to SARS-CoV-2 infection in human PSC-derived cardiomyocytes and primary endothelial cells

The pathogenicity of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been attributed to its ability to enter through the membrane-bound angiotensin-converting enzyme 2 (ACE2) receptor. Therefore, it has been heavily speculated that angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) therapy may modulate SARS-CoV-2 infection. In this study, exposure of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) and human endothelial cells (hECs) to SARS-CoV-2 identified significant differences in protein coding genes involved in immunity, viral response, and cardiomyocyte/endothelial structure. Specifically, transcriptome changes were identified in the tumor necrosis factor (TNF), interferon α/β, and mitogen-activated protein kinase (MAPK) (hPSC-CMs) as well as nuclear factor kappa-B (NF-κB) (hECs) signaling pathways. However, pre-treatment of hPSC-CMs or hECs with two widely prescribed antihypertensive medications, losartan and lisinopril, did not affect the susceptibility of either cell type to SARS-CoV-2 infection. These findings demonstrate the toxic effects of SARS-CoV-2 in hPSC-CMs/hECs and, taken together with newly emerging multicenter trials, suggest that antihypertensive drug treatment alone does not alter SARS-CoV-2 infection.

Direct targeting of TDP-43, from small molecules to biologics: the therapeutic landscape

Tar DNA binding (TDP)-43 proteinopathy, typically described as cytoplasmic accumulation of highly modified and misfolded TDP-43 molecules, is characteristic of several neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS) and limbic-predominant age-related TDP-43 encephalopathy (LATE). TDP-43 proposed proteinopathies include homeostatic imbalance between nuclear and cytoplasmic localization, aggregation of ubiquitinated and hyper-phosphorylated TDP-43, and an increase in protein truncation of cytoplasmic TDP-43. Given the therapeutic interest of targeting TDP-43, this review focuses on the current landscape of strategies, ranging from biologics to small molecules, that directly target TDP-43. Antibodies, peptides and compounds have been designed or found to recognize specific TDP-43 sequences but alleviate TDP-43 toxicity through different mechanisms. While two antibodies described here were able to induce degradation of pathological TDP-43, the peptides and small molecules were primarily designed to reduce aggregation of TDP-43. Furthermore, we discuss promising emerging therapeutic targets.

In Silico Targeting of the Long Noncoding RNA MALAT1

RNA targeting has gained traction over the past decade. It has become clear that dysregulation of RNA can be linked to many diseases, leading to a need for new scaffolds recognizing RNA specifically. Long noncoding RNAs are emerging as key controllers of gene expression and potential therapeutic targets. However, traditional targeting methods have overwhelmingly been focused on proteins. In this study, we used a protein computational tool and found several possible targetable pockets in a structurally characterized long noncoding RNA, MALAT1. Screening against those identified pockets revealed several hit compounds. We tested the binding of those compounds to MALAT1 RNA and tRNA as a negative control, using SPR. While several compounds were nonspecific binders, others were able to recognize MALAT1 specifically. One of them, MTC07, has an apparent affinity of 400.2 ± 14.4 μM. Although it has weak affinity, MTC07 is the first compound targeting MALAT1 originating from in silico docking.

Mucosal IL-4R antagonist HIV vaccination with SOSIP-gp140 booster can induce high-quality cytotoxic CD4+/CD8+ T cells and humoral responses in macaques

Inducing humoral, cellular and mucosal immunity is likely to improve the effectiveness of HIV-1 vaccine strategies. Here, we tested a vaccine regimen in pigtail macaques using an intranasal (i.n.) recombinant Fowl Pox Virus (FPV)-gag pol env-IL-4R antagonist prime, intramuscular (i.m.) recombinant Modified Vaccinia Ankara Virus (MVA)-gag pol-IL-4R antagonist boost followed by an i.m SOSIP-gp140 boost. The viral vector-expressed IL-4R antagonist transiently inhibited IL-4/IL-13 signalling at the vaccination site. The SOSIP booster not only induced gp140-specific IgG, ADCC (antibody-dependent cellular cytotoxicity) and some neutralisation activity, but also bolstered the HIV-specific cellular and humoral responses. Specifically, superior sustained systemic and mucosal HIV Gag-specific poly-functional/cytotoxic CD4⁺ and CD8⁺ T cells were detected with the IL-4R antagonist adjuvanted strategy compared to the unadjuvanted control. In the systemic compartment elevated Granzyme K expression was linked to CD4⁺ T cells, whilst Granzyme B/TIA-1 to CD8⁺ T cells. In contrast, the cytotoxic marker expression by mucosal CD4⁺ and CD8⁺ T cells differed according to the mucosal compartment. This vector-based mucosal IL-4R antagonist/SOSIP booster strategy, which promotes cytotoxic mucosal CD4⁺ T cells at the first line of defence, and cytotoxic CD4⁺ and CD8⁺ T cells plus functional antibodies in the blood, may prove valuable in combating mucosal infection with HIV-1 and warrants further investigation.

An Allosteric Modulator of RNA Binding Targeting the N-Terminal Domain of TDP-43 Yields Neuroprotective Properties

In this study, we targeted the N-terminal domain (NTD) of transactive response (TAR) DNA binding protein (TDP-43), which is implicated in several neurodegenerative diseases. In silico docking of 50K compounds to the NTD domain of TDP-43 identified a small molecule (nTRD22) that is bound to the N-terminal domain. Interestingly, nTRD22 caused allosteric modulation of the RNA binding domain (RRM) of TDP-43, resulting in decreased binding to RNA in vitro. Moreover, incubation of primary motor neurons with nTRD22 induced a reduction of TDP-43 protein levels, similar to TDP-43 RNA binding-deficient mutants and supporting a disruption of TDP-43 binding to RNA. Finally, nTRD22 mitigated motor impairment in a Drosophila model of amyotrophic lateral sclerosis. Our findings provide an exciting way of allosteric modulation of the RNA-binding region of TDP-43 through the N-terminal domain.

Abstract LB-226: Discovery of small molecule Mcl-1 and Bfl-1 inhibitors

Anti-apoptotic Bcl-2 family proteins are frequently overexpressed in various cancers and are established therapeutic targets. Cancer cells can either display dependence on individual or subsets of these pro-survival proteins, which gives therapeutic relevance to both selective and multimodal inhibitors. Selective Bcl-2, Bcl-xL, and Mcl-1 inhibitors are being evaluated clinically in a wide spectrum of cancers. Bfl-1 is another homologous anti-apoptotic protein with closest structural relation to Mcl-1, but drug discovery efforts on this protein have been limited to peptide inhibitors. There is increasing evidence of Bfl-1 being a viable therapeutic target, particularly in the context of drug resistance. Both Mcl-1 and Bfl-1 share the selective endogenous binding partner, Noxa, which highlights the relevance of these proteins being therapeutically co-inhibited, especially in cancers where they are commonly overexpressed together. Mcl-1 and Bfl-1 have emerged as key players in melanoma, associated with poor clinical responses to BRAF/MEK pathway inhibitors and cell death resistance, thus representing attractive new therapeutic targets.We report herein the structure-based design, synthesis, SAR, and biological characterization of dual inhibitors displaying equipotent binding to Mcl-1 and Bfl-1. This class of inhibitors was designed based on the validated hit molecule identified in our recently reported integrated high throughput and virtual screening study. Several co-crystal structures of these molecules were solved, which guided the structure-based design efforts and led to the optimization of compounds that bind both Mcl-1 and Bfl-1 with Ki values in the 100 nM range and >250-fold selectivity over Bcl-2/Bcl-xL. Direct binding of optimized inhibitors to the Mcl-1 and Bfl-1 proteins was validated by several biophysical methods, including HSQC-NMR, and bio-layer interferometry (BLI). Selectivity over Bcl-2/Bcl-xL was demonstrated on the cellular level by the ability to selectively bind endogenous Mcl-1 and Bfl-1 and disrupt interactions with Bim. On-target cellular activity was further confirmed using Eµ-Myc lymphoma cell lines, which stably overexpress individual anti-apoptotic Bcl-2 proteins with a strong survival dependence on each of these targets. Eµ-Myc cells overexpressing Mcl-1 and Bfl-1 showed dose-dependent cell death in response to treatment with the most potent compounds, while cells overexpressing Bcl-2 and Bcl-xL were not affected even at the highest tested concentration, further demonstrating the selective targeting of Mcl-1 and Bfl-1. With a selective set of chemical tools, we employed the BH3 profiling assay across a panel of melanoma cell lines in order to functionally dissect survival dependence. The obtained data suggests that melanoma cell lines mainly rely on Bcl-xL and Mcl-1, with certain cell lines displaying increased involvement of Bfl-1. Importantly, the vemurafenib resistant SK-MEL-239 melanoma cell line showed increased functional Mcl-1 and Bfl-1 dependence compared to the parental line. Overall, this work contributes to the drug discovery efforts of Bcl-2 family inhibitors and provides novel dual Mcl-1/Bfl-1 selective inhibitors. Further optimization of these dual inhibitors may provide valuable therapeutics to help combat acquired resistance in melanoma, where Mcl-1 and Bfl-1 play prominent functional roles, as determined by BH3 profiling.

Citation Format: Karson J. Kump, Lei Miao, Ahmed A. Mady, Nurul H. Ansari, Uttar K. Shrestha, Yuting Yang, Mohan Pal, Chenzhong Liao, Andrej Perdih, Fardokht A. Abulwerdi, Krishnapriya Chinnaswamy, Jennifer L. Meagher, Jacob M. Carlson, May Khanna, Jeanne A. Stuckey, Zaneta Nikolovska-Coleska. Discovery of small molecule Mcl-1 and Bfl-1 inhibitors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-226.

Evaluation of edonerpic maleate as a CRMP2 inhibitor for pain relief

We have previously reported that the microtubule-associated collapsin response mediator protein 2 (CRMP2) is necessary for the expression of chronic pain. CRMP2 achieves this control of nociceptive signaling by virtue of its ability to regulate voltage-gated calcium and sodium channels. To date, however, no drugs exist that target CRMP2. Recently, the small molecule edonerpic maleate (1 -{3-[2-(1-benzothiophen-5-yl)ethoxy]propyl}azetidin-3-ol maleate), a candidate therapeutic for Alzheimer’s disease was reported to be a novel CRMP2 binding compound with the potential to decrease its phosphorylation level in cortical tissues in vivo. Here we sought to determine the mechanism of action of edonerpic maleate and test its possible effect in a rodent model of chronic pain. We observed: (i) no binding between human CRMP2 and edonerpic maleate; (ii) edonerpic maleate had no effect on CRMP2 expression and phosphorylation in dorsal root ganglion (DRG) neurons; (iii) edonerpic maleate-decreased calcium but increased sodium current density in DRG neurons; and (iv) edonerpic maleate was ineffective in reversing post-surgical allodynia in male and female mice. Thus, while CRMP2 inhibiting compounds remain a viable strategy for developing new mechanism-based pain inhibitors, edonerpic maleate is an unlikely candidate.

Discovery and Characterization of 2,5-Substituted Benzoic Acid Dual Inhibitors of the Anti-apoptotic Mcl-1 and Bfl-1 Proteins

Anti-apoptotic Bcl-2 family proteins are overexpressed in a wide spectrum of cancers and have become well validated therapeutic targets. Cancer cells display survival dependence on individual or subsets of anti-apoptotic proteins that could be effectively targeted by multimodal inhibitors. We designed a 2,5-substituted benzoic acid scaffold that displayed equipotent binding to Mcl-1 and Bfl-1. Structure-based design was guided by several solved cocrystal structures with Mcl-1, leading to the development of compound 24, which binds both Mcl-1 and Bfl-1 with K_i values of 100 nM and shows appreciable selectivity over Bcl-2/Bcl-xL. The selective binding profile of 24 was translated to on-target cellular activity in model lymphoma cell lines. These studies lay a foundation for developing more advanced dual Mcl-1/Bfl-1 inhibitors that have potential to provide greater single agent efficacy and broader coverage to combat resistance in several types of cancer than selective Mcl-1 inhibitors alone.

The Natural Flavonoid Naringenin Elicits Analgesia through Inhibition of NaV1.8 Voltage-Gated Sodium Channels

Naringenin (2S)-5,7-dihydroxy-2-(4-hydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-4-one is a natural flavonoid found in fruits from the citrus family. Because (2S)-naringenin is known to racemize, its bioactivity might be related to one or both enantiomers. Computational studies predicted that (2R)-naringenin may act on voltage-gated ion channels, particularly the N-type calcium channel (CaV2.2) and the NaV1.7 sodium channel-both of which are key for pain signaling. Here we set out to identify the possible mechanism of action of naringenin. Naringenin inhibited depolarization-evoked Ca²⁺ influx in acetylcholine-, ATP-, and capsaicin-responding rat dorsal root ganglion (DRG) neurons. This was corroborated in electrophysiological recordings from DRG neurons. Pharmacological dissection of each of the voltage-gated Ca²⁺ channels subtypes could not pinpoint any selectivity of naringenin. Instead, naringenin inhibited NaV1.8-dependent and tetrodotoxin (TTX)-resistant while sparing tetrodotoxin sensitive (TTX-S) voltage-gated Na⁺ channels as evidenced by the lack of further inhibition by the NaV1.8 blocker A-803467. The effects of the natural flavonoid were validated ex vivo in spinal cord slices where naringenin decreased both the frequency and amplitude of sEPSC recorded in neurons within the substantia gelatinosa. The antinociceptive potential of naringenin was evaluated in male and female mice. Naringenin had no effect on the nociceptive thresholds evoked by heat. Naringenin's reversed allodynia was in mouse models of postsurgical and neuropathic pain. Here, driven by a call by the National Center for Complementary and Integrative Health's strategic plan to advance fundamental research into basic biological mechanisms of the action of natural products, we advance the antinociceptive potential of the flavonoid naringenin.

Structural Insights Into TDP-43 and Effects of Post-translational Modifications

Transactive response DNA binding protein (TDP-43) is a key player in neurodegenerative diseases. In this review, we have gathered and presented structural information on the different regions of TDP-43 with high resolution structures available. A thorough understanding of TDP-43 structure, effect of modifications, aggregation and sites of localization is necessary as we develop therapeutic strategies targeting TDP-43 for neurodegenerative diseases. We discuss how different domains as well as post-translational modification may influence TDP-43 overall structure, aggregation and droplet formation. The primary aim of the review is to utilize structural insights as we develop an understanding of the deleterious behavior of TDP-43 and highlight locations of established and proposed post-translation modifications. TDP-43 structure and effect on localization is paralleled by many RNA-binding proteins and this review serves as an example of how structure may be modulated by numerous compounding elements.

Small Molecule Targeting TDP-43's RNA Recognition Motifs Reduces Locomotor Defects in a Drosophila Model of Amyotrophic Lateral Sclerosis (ALS)

RNA dysregulation likely contributes to disease pathogenesis of amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases. A pathological form of the transactive response (TAR) DNA binding protein (TDP-43) binds to RNA in stress granules and forms membraneless, amyloid-like TDP-43 aggregates in the cytoplasm of ALS motor neurons. In this study, we hypothesized that by targeting the RNA recognition motif (RRM) domains of TDP-43 that confer a pathogenic interaction between TDP-43 and RNA, motor neuron toxicity could be reduced. In silico docking of 50000 compounds to the RRM domains of TDP-43 identified a small molecule (rTRD01) that (i) bound to TDP-43's RRM1 and RRM2 domains, (ii) partially disrupted TDP-43's interaction with the hexanucleotide RNA repeat of the disease-linked c9orf72 gene, but not with (UG)₆ canonical binding sequence of TDP-43, and (iii) improved larval turning, an assay measuring neuromuscular coordination and strength, in an ALS fly model based on the overexpression of mutant TDP-43. Our findings provide an instructive example of a chemical biology approach pivoted to discover small molecules targeting RNA-protein interactions in neurodegenerative diseases.

Betulinic acid, derived from the desert lavender Hyptis emoryi, attenuates paclitaxel-, HIV-, and nerve injury-associated peripheral sensory neuropathy via block of N- and T-type calcium channels

The Federal Pain Research Strategy recommended development of nonopioid analgesics as a top priority in its strategic plan to address the significant public health crisis and individual burden of chronic pain faced by >100 million Americans. Motivated by this challenge, a natural product extracts library was screened and identified a plant extract that targets activity of voltage-gated calcium channels. This profile is of interest as a potential treatment for neuropathic pain. The active extract derived from the desert lavender plant native to southwestern United States, when subjected to bioassay-guided fractionation, afforded 3 compounds identified as pentacyclic triterpenoids, betulinic acid (BA), oleanolic acid, and ursolic acid. Betulinic acid inhibited depolarization-evoked calcium influx in dorsal root ganglion (DRG) neurons predominantly through targeting low-voltage-gated (Cav3 or T-type) and CaV2.2 (N-type) calcium channels. Voltage-clamp electrophysiology experiments revealed a reduction of Ca, but not Na, currents in sensory neurons after BA exposure. Betulinic acid inhibited spontaneous excitatory postsynaptic currents and depolarization-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices. Notably, BA did not engage human mu, delta, or kappa opioid receptors. Intrathecal administration of BA reversed mechanical allodynia in rat models of chemotherapy-induced peripheral neuropathy and HIV-associated peripheral sensory neuropathy as well as a mouse model of partial sciatic nerve ligation without effects on locomotion. The broad-spectrum biological and medicinal properties reported, including anti-HIV and anticancer activities of BA and its derivatives, position this plant-derived small molecule natural product as a potential nonopioid therapy for management of chronic pain.

1H, 15N and 13C backbone assignment of apo TDP-43 RNA recognition motifs

TAR DNA-binding protein 43 (TDP-43) is a ubiquitously expressed nuclear protein that influences diverse cellular processes by regulating alternative splicing of RNA and microRNA biogenesis. It is also a pathological protein found in sporadic ALS and in the most common subtype of frontotemporal lobar degeneration with ubiquitinated inclusions (FLTD-U). TDP-43 has two tandem RNA-binding domains, RRM1 and RRM2. The NMR structure of TDP-43 was solved in the presence of UG-rich RNA sequences bound to the RRM1 and RRM2 domains. Here we report the backbone assignment of apo TDP-43. The chemical shift (HN, N, C, C^α and C^β) analysis shows the predicted regions of secondary structure are in good agreement with those observed for TDP-43 in complex with RNA. However, our data show that the apo structure of TPD-43 has increased flexibility in the regions that would normally have been used to anchor the RNA bases. The backbone chemical shifts assignments will prove useful in the study of TDP-43 interaction with non-canonical RNA and RRM-binding proteins.

(-)-Hardwickiic Acid and Hautriwaic Acid Induce Antinociception via Blockade of Tetrodotoxin-Sensitive Voltage-Dependent Sodium Channels

For an affliction that debilitates an estimated 50 million adults in the United States, the current chronic pain management approaches are inadequate. The Centers for Disease Control and Prevention have called for a minimization in opioid prescription and use for chronic pain conditions, and thus, it is imperative to discover alternative non-opioid based strategies. For the realization of this call, a library of natural products was screened in search of pharmacological inhibitors of both voltage-gated calcium channels and voltage-gated sodium channels, which are excellent targets due to their well-established roles in nociceptive pathways. We discovered (-)-hardwickiic acid ((-)-HDA) and hautriwaic acid (HTA) isolated from plants, Croton californicus and Eremocarpus setigerus, respectively, inhibited tetrodotoxin-sensitive sodium, but not calcium or potassium, channels in small diameter, presumptively nociceptive, dorsal root ganglion (DRG) neurons. Failure to inhibit spontaneous postsynaptic excitatory currents indicated a preferential targeting of voltage-gated sodium channels over voltage-gated calcium channels by these extracts. Neither compound was a ligand at opioid receptors. Finally, we identified the potential of both (-)-HDA and HTA to reverse chronic pain behavior in preclinical rat models of HIV-sensory neuropathy, and for (-)-HDA specifically, in chemotherapy-induced peripheral neuropathy. Our results illustrate the therapeutic potential for (-)-HDA and HTA for chronic pain management and could represent a scaffold, that, if optimized by structure-activity relationship studies, may yield novel specific sodium channel antagonists for pain relief.

The principles of tomorrow's university

In the 21st Century, research is increasingly data- and computation-driven. Researchers, funders, and the larger community today emphasize the traits of openness and reproducibility. In March 2017, 13 mostly early-career research leaders who are building their careers around these traits came together with ten university leaders (presidents, vice presidents, and vice provosts), representatives from four funding agencies, and eleven organizers and other stakeholders in an NIH- and NSF-funded one-day, invitation-only workshop titled "Imagining Tomorrow's University." Workshop attendees were charged with launching a new dialog around open research - the current status, opportunities for advancement, and challenges that limit sharing. The workshop examined how the internet-enabled research world has changed, and how universities need to change to adapt commensurately, aiming to understand how universities can and should make themselves competitive and attract the best students, staff, and faculty in this new world. During the workshop, the participants re-imagined scholarship, education, and institutions for an open, networked era, to uncover new opportunities for universities to create value and serve society. They expressed the results of these deliberations as a set of 22 principles of tomorrow's university across six areas: credit and attribution, communities, outreach and engagement, education, preservation and reproducibility, and technologies. Activities that follow on from workshop results take one of three forms. First, since the workshop, a number of workshop authors have further developed and published their white papers to make their reflections and recommendations more concrete. These authors are also conducting efforts to implement these ideas, and to make changes in the university system.  Second, we plan to organise a follow-up workshop that focuses on how these principles could be implemented. Third, we believe that the outcomes of this workshop support and are connected with recent theoretical work on the position and future of open knowledge institutions.

A Chemical Biology Approach to Model Pontocerebellar Hypoplasia Type 1B (PCH1B)

Mutations of EXOSC3 have been linked to the rare neurological disorder known as Pontocerebellar Hypoplasia type 1B (PCH1B). EXOSC3 is one of three putative RNA-binding structural cap proteins that guide RNA into the RNA exosome, the cellular machinery that degrades RNA. Using RNAcompete, we identified a G-rich RNA motif binding to EXOSC3. Surface plasmon resonance (SPR) and microscale thermophoresis (MST) indicated an affinity in the low micromolar range of EXOSC3 for long and short G-rich RNA sequences. Although several PCH1B-causing mutations in EXOSC3 did not engage a specific RNA motif as shown by RNAcompete, they exhibited lower binding affinity to G-rich RNA as demonstrated by MST. To test the hypothesis that modification of the RNA-protein interface in EXOSC3 mutants may be phenocopied by small molecules, we performed an in-silico screen of 50 000 small molecules and used enzyme-linked immunosorbant assays (ELISAs) and MST to assess the ability of the molecules to inhibit RNA-binding by EXOSC3. We identified a small molecule, EXOSC3-RNA disrupting (ERD) compound 3 (ERD03), which ( i) bound specifically to EXOSC3 in saturation transfer difference nuclear magnetic resonance (STD-NMR), ( ii) disrupted the EXOSC3-RNA interaction in a concentration-dependent manner, and ( iii) produced a PCH1B-like phenotype with a 50% reduction in the cerebellum and an abnormally curved spine in zebrafish embryos. This compound also induced modification of zebrafish RNA expression levels similar to that observed with a morpholino against EXOSC3. To our knowledge, this is the first example of a small molecule obtained by rational design that models the abnormal developmental effects of a neurodegenerative disease in a whole organism.

Inhibition of the Ubc9 E2 SUMO-conjugating enzyme-CRMP2 interaction decreases NaV1.7 currents and reverses experimental neuropathic pain

We previously reported that destruction of the small ubiquitin-like modifier (SUMO) modification site in the axonal collapsin response mediator protein 2 (CRMP2) was sufficient to selectively decrease trafficking of the voltage-gated sodium channel NaV1.7 and reverse neuropathic pain. Here, we further interrogate the biophysical nature of the interaction between CRMP2 and the SUMOylation machinery, and test the hypothesis that a rationally designed CRMP2 SUMOylation motif (CSM) peptide can interrupt E2 SUMO-conjugating enzyme Ubc9-dependent modification of CRMP2 leading to a similar suppression of NaV1.7 currents. Microscale thermophoresis and amplified luminescent proximity homogeneous alpha assay revealed a low micromolar binding affinity between CRMP2 and Ubc9. A heptamer peptide harboring CRMP2's SUMO motif, also bound with similar affinity to Ubc9, disrupted the CRMP2-Ubc9 interaction in a concentration-dependent manner. Importantly, incubation of a tat-conjugated cell-penetrating peptide (t-CSM) decreased sodium currents, predominantly NaV1.7, in a model neuronal cell line. Dialysis of t-CSM peptide reduced CRMP2 SUMOylation and blocked surface trafficking of NaV1.7 in rat sensory neurons. Fluorescence dye-based imaging in rat sensory neurons demonstrated inhibition of sodium influx in the presence of t-CSM peptide; by contrast, calcium influx was unaffected. Finally, t-CSM effectively reversed persistent mechanical and thermal hypersensitivity induced by a spinal nerve injury, a model of neuropathic pain. Structural modeling has now identified a pocket-harboring CRMP2's SUMOylation motif that, when targeted through computational screening of ligands/molecules, is expected to identify small molecules that will biochemically and functionally target CRMP2's SUMOylation to reduce NaV1.7 currents and reverse neuropathic pain.

Chemical shift perturbation mapping of the Ubc9-CRMP2 interface identifies a pocket in CRMP2 amenable for allosteric modulation of Nav1.7 channels

Drug discovery campaigns directly targeting the voltage-gated sodium channel NaV1.7, a highly prized target in chronic pain, have not yet been clinically successful. In a differentiated approach, we demonstrated allosteric control of trafficking and activity of NaV1.7 by prevention of SUMOylation of collapsin response mediator protein 2 (CRMP2). Spinal administration of a SUMOylation incompetent CRMP2 (CRMP2 K374A) significantly attenuated pain behavior in the spared nerve injury (SNI) model of neuropathic pain, underscoring the importance of SUMOylation of CRMP2 as a pathologic event in chronic pain. Using a rational design strategy, we identified a heptamer peptide harboring CRMP2's SUMO motif that disrupted the CRMP2-Ubc9 interaction, inhibited CRMP2 SUMOylation, inhibited NaV1.7 membrane trafficking, and specifically inhibited NaV1.7 sodium influx in sensory neurons. Importantly, this peptide reversed nerve injury-induced thermal and mechanical hypersensitivity in the SNI model, supporting the practicality of discovering pain drugs by indirectly targeting NaV1.7 via prevention of CRMP2 SUMOylation. Here, our goal was to map the unique interface between CRMP2 and Ubc9, the E2 SUMO conjugating enzyme. Using computational and biophysical approaches, we demonstrate the enzyme/substrate nature of Ubc9/CRMP2 binding and identify hot spots on CRMP2 that may form the basis of future drug discovery campaigns disrupting the CRMP2-Ubc9 interaction to recapitulate allosteric regulation of NaV1.7 for pain relief.

IL-5-stimulated eosinophils adherent to periostin undergo stereotypic morphological changes and ADAM8-dependent migration

BACKGROUND

IL-5 causes suspended eosinophils to polarize with filamentous (F)-actin and granules at one pole and the nucleus in a specialized uropod, the "nucleopod," which is capped with P-selectin glycoprotein ligand-1 (PSGL-1). IL-5 enhances eosinophil adhesion and migration on periostin, an extracellular matrix protein upregulated in asthma by type 2 immunity mediators.

OBJECTIVE

Determine how the polarized morphology evolves to foster migration of IL-5-stimulated eosinophils on a surface coated with periostin.

METHODS

Blood eosinophils adhering to adsorbed periostin were imaged at different time points by fluorescent microscopy, and migration of eosinophils on periostin was assayed.

RESULTS

After 10 minutes in the presence of IL-5, adherent eosinophils were polarized with PSGL-1 at the nucleopod tip and F-actin distributed diffusely at the opposite end. After 30-60 minutes, the nucleopod had dissipated such that PSGL-1 was localized in a crescent or ring away from the cell periphery, and F-actin was found in podosome-like structures. The periostin layer, detected with monoclonal antibody Stiny-1, shown here to recognize the FAS1 4 module, was cleared in wide areas around adherent eosinophils. Clearance was attenuated by metalloproteinase inhibitors or antibodies to disintegrin metalloproteinase 8 (ADAM8), a major eosinophil metalloproteinase previously implicated in asthma pathogenesis. ADAM8 was not found in podosome-like structures, which are associated with proteolytic activity in other cell types. Instead, immunoblotting demonstrated proteoforms of ADAM8 that lack the cytoplasmic tail in the supernatant. Anti-ADAM8 inhibited migration of IL-5-stimulated eosinophils on periostin.

CONCLUSIONS AND CLINICAL RELEVANCE

Migrating IL-5-activated eosinophils on periostin exhibit loss of nucleopodal features and appearance of prominent podosomes along with clearance of the Stiny-1 periostin epitope. Migration and epitope clearance are both attenuated by inhibitors of ADAM8. We propose, therefore, that eosinophils remodel and migrate on periostin-rich extracellular matrix in the asthmatic airway in an ADAM8-dependent manner, making ADAM8 a possible therapeutic target.

Homology-guided mutational analysis reveals the functional requirements for antinociceptive specificity of collapsin response mediator protein 2-derived peptides

BACKGROUND AND PURPOSE

N-type voltage-gated calcium (Ca_v 2.2) channels are critical determinants of increased neuronal excitability and neurotransmission accompanying persistent neuropathic pain. Although Ca_v 2.2 channel antagonists are recommended as first-line treatment for neuropathic pain, calcium-current blocking gabapentinoids inadequately alleviate chronic pain symptoms and often exhibit numerous side effects. Collapsin response mediator protein 2 (CRMP2) targets Ca_v 2.2 channels to the sensory neuron membrane and allosterically modulates their function. A 15-amino-acid peptide (CBD3), derived from CRMP2, disrupts the functional protein-protein interaction between CRMP2 and Ca_v 2.2 channels to inhibit calcium influx, transmitter release and acute, inflammatory and neuropathic pain. Here, we have mapped the minimal domain of CBD3 necessary for its antinociceptive potential.

EXPERIMENTAL APPROACH

Truncated as well as homology-guided mutant versions of CBD3 were generated and assessed using depolarization-evoked calcium influx in rat dorsal root ganglion neurons, binding between CRMP2 and Ca_v 2.2 channels, whole-cell voltage clamp electrophysiology and behavioural effects in two models of experimental pain: post-surgical pain and HIV-induced sensory neuropathy induced by the viral glycoprotein 120.

KEY RESULTS

The first six amino acids within CBD3 accounted for all in vitro activity and antinociception. Spinal administration of a prototypical peptide (TAT-CBD3-L5M) reversed pain behaviours. Homology-guided mutational analyses of these six amino acids identified at least two residues, Ala1 and Arg4, as being critical for antinociception in two pain models.

CONCLUSIONS AND IMPLICATIONS

These results identify an antinociceptive scaffold core in CBD3 that can be used for development of low MW mimetics of CBD3.

LINKED ARTICLES

This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.

A single structurally conserved SUMOylation site in CRMP2 controls NaV1.7 function

The neuronal collapsin response mediator protein 2 (CRMP2) undergoes several posttranslational modifications that codify its functions. Most recently, CRMP2 SUMOylation (addition of small ubiquitin like modifier (SUMO)) was identified as a key regulatory step within a modification program that codes for CRMP2 interaction with, and trafficking of, voltage-gated sodium channel NaV1.7. In this paper, we illustrate the utility of combining sequence alignment within protein families with structural analysis to identify, from several putative SUMOylation sites, those that are most likely to be biologically relevant. Co-opting this principle to CRMP2, we demonstrate that, of 3 sites predicted to be SUMOylated in CRMP2, only the lysine 374 site is a SUMOylation client. A reduction in NaV1.7 currents was the corollary of the loss of CRMP2 SUMOylation at this site. A 1.78-Å-resolution crystal structure of mouse CRMP2 was solved using X-ray crystallography, revealing lysine 374 as buried within the CRMP2 tetramer interface but exposed in the monomer. Since CRMP2 SUMOylation is dependent on phosphorylation, we postulate that this state forces CRMP2 toward a monomer, exposing the SUMO site and consequently, resulting in constitutive regulation of NaV1.7.

Prospective randomised comparison of ring versus rail fixator in infected gap nonunion of tibia treated with distraction osteogenesis

AIMS

This is a prospective randomised study which compares the radiological and functional outcomes of ring and rail fixators in patients with an infected gap (> 3 cm) nonunion of the tibia.

PATIENTS AND METHODS

Between May 2008 and February 2013, 70 patients were treated at our Institute for a posttraumatic osseocutaneous defect of the tibia measuring at least 3 cm. These were randomised into two groups of 35 patients using the lottery method. Group I patients were treated with a ring fixator and group II patients with a rail fixator. The mean age was 33.2 years (18 to 64) in group I and 29.3 years (18 to 65) in group II. The mean bone gap was 5.84 cm in group I and 5.78 cm in group II. The mean followup was 33.8 months in group I and 32.6 months in group II. Bone and functional results were assessed using the classification of the Association for the Study and Application of the Method of Ilizarov (ASAMI). Functional results were also assessed at six months using the short musculoskeletal functional assessment (SMFA) score.

RESULTS

The bone result was excellent, good, fair and poor in 21, 12, 0 and 2 in group I; and 14, 15, 3, and 3 in group II, respectively. The functional results were excellent, good, fair, poor and failure in 16, 17, 1, 0 and 1 in group I; and 22, 10, 0, 3 and 0 in group II, respectively. Both fixator systems achieved comparable rates of union and functional outcomes. The rate of deep pintract infection was significantly higher in the rail fixator group but patients found it more comfortable.

CONCLUSION

We recommend the use of a ring fixator in patients with a bone gap of more than 6 cm. Patients with a bone gap up to 6 cm can be managed with either a ring or rail fixator. Cite this article: Bone Joint J 2016;98B:1399-1405.

Physes around the shoulder girdle: normal development and injury patterns

Traumatic injuries involving the scapula and clavicle in skeletally immature patients have unique characteristics that distinguish them from similar injuries in the mature skeleton. Fractures involving unossified cartilage and unfused epiphyses are difficult to appreciate on plain radiographs and computed tomography (CT) imaging. Knowledge of the developmental anatomy and normal radiological appearances during different stages of development of these bones is an essential prerequisite for the radiologist tasked with interpreting the imaging of such injuries in order to avoid potential diagnostic pitfalls. With increased availability and improved resolution of magnetic resonance imaging (MRI), we are now better able to distinguish between true joint dislocations and epiphyseal injuries. Making this distinction is important because it can have implications with regards to how the patient is managed and the prognosis.

A membrane-delimited N-myristoylated CRMP2 peptide aptamer inhibits CaV2.2 trafficking and reverses inflammatory and postoperative pain behaviors

Targeting proteins within the N-type voltage-gated calcium channel (CaV2.2) complex has proven to be an effective strategy for developing novel pain therapeutics. We describe a novel peptide aptamer derived from the collapsin response mediator protein 2 (CRMP2), a CaV2.2-regulatory protein. Addition of a 14-carbon myristate group to the peptide (myr-tat-CBD3) tethered it to the membrane of primary sensory neurons near surface CaV2.2. Pull-down studies demonstrated that myr-tat-CBD3 peptide interfered with the CRMP2-CaV2.2 interaction. Quantitative confocal immunofluorescence revealed a pronounced reduction of CaV2.2 trafficking after myr-tat-CBD3 treatment and increased efficiency in disrupting CRMP2-CaV2.2 colocalization compared with peptide tat-CBD3. Consequently, myr-tat-CBD3 inhibited depolarization-induced calcium influx in sensory neurons. Voltage clamp electrophysiology experiments revealed a reduction of Ca, but not Na, currents in sensory neurons after myr-tat-CBD3 exposure. Current clamp electrophysiology experiments demonstrated a reduction in excitability of small-diameter dorsal root ganglion neurons after exposure to myr-tat-CBD3. Myr-tat-CBD3 was effective in significantly attenuating carrageenan-induced thermal hypersensitivity and reversing thermal hypersensitivity induced by a surgical incision of the plantar surface of the rat hind paw, a model of postoperative pain. These effects are compared with those of tat-CBD3-the nonmyristoylated tat-conjugated CRMP2 peptide as well as scrambled versions of CBD3 and CBD3-lacking control peptides. Our results demonstrate that the myristoyl tag enhances intracellular delivery and local concentration of the CRMP2 peptide aptamer near membrane-delimited calcium channels resulting in pronounced interference with the calcium channel complex, superior suppression of calcium influx, and better antinociceptive potential.

Quality indicators for the primary care of osteoarthritis: a systematic review

OBJECTIVE

To identify valid and feasible quality indicators for the primary care of osteoarthritis (OA).

DESIGN

Systematic review and narrative synthesis.

DATA SOURCES

Electronic reference databases (MEDLINE, EMBASE, CINAHL, HMIC, PsychINFO), quality indicator repositories, subject experts.

ELIGIBILITY CRITERIA

Eligible articles referred to adults with OA, focused on development or implementation of quality indicators, and relevant to UK primary care. An English language restriction was used. The date range for the search was January 2000 to August 2013. The majority of OA management guidance has been published within this time frame.

DATA EXTRACTION

Relevant studies were quality assessed using previous quality indicator methodology. Two reviewers independently extracted data. Articles were assessed through the Outcome Measures in Rheumatology filter; indicators were mapped to management guidance for OA in adults. A narrative synthesis was used to combine the indicators within themes.

RESULTS

10,853 articles were identified from the search; 32 were included in the review. Fifteen indicators were considered valid and feasible for implementation in primary care; these related to assessment non-pharmacological and pharmacological management. Another 10 indicators were considered less feasible, in various aspects of assessment and management. A small number of recommendations had no published corresponding quality indicator, such as use of topical non-steroidal anti-inflammatory drugs. No negative ('do not do') indicators were identified.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

There are well-developed, feasible indicators of quality of care for OA which could be implemented in primary care. Their use would assist the audit and quality improvement for this common and frequently disabling condition.

Differential neuroprotective potential of CRMP2 peptide aptamers conjugated to cationic, hydrophobic, and amphipathic cell penetrating peptides

The microtubule-associated axonal specification collapsin response mediator protein 2 (CRMP2) is a novel target for neuroprotection. A CRMP2 peptide (TAT-CBD3) conjugated to the HIV transactivator of transcription (TAT) protein's cationic cell penetrating peptide (CPP) motif protected neurons in the face of toxic levels of Ca(2+) influx leaked in via N-methyl-D-aspartate receptor (NMDAR) hyperactivation. Here we tested whether replacing the hydrophilic TAT motif with alternative cationic (nona-arginine (R9)), hydrophobic (membrane transport sequence (MTS) of k-fibroblast growth factor) or amphipathic (model amphipathic peptide (MAP)) CPPs could be superior to the neuroprotection bestowed by TAT-CBD3. In giant plasma membrane vesicles (GPMVs) derived from cortical neurons, the peptides translocated across plasma membranes with similar efficiencies. Cortical neurons, acutely treated with peptides prior to a toxic glutamate challenge, demonstrated enhanced efflux of R9-CBD3 compared to others. R9-CBD3 inhibited N-methyl-D-aspartate (NMDA)-evoked Ca(2+) influx to a similar extent as TAT-CBD3 while MTS-CBD3 was ineffective which correlated with the ability of R9- and TAT-CBD3, but not MTS-CBD3, to block NMDAR interaction with CRMP2. Unrestricted Ca(2+) influx through NMDARs leading to delayed calcium dysregulation and neuronal cell death was blocked by all peptides but MAP-CBD3. When applied acutely for 10 min, R9-CBD3 was more effective than TAT-CBD3 at neuroprotection while MTS- and MAP-CBD3 were ineffective. In contrast, long-term (>24 h) treatment with MTS-CBD3 conferred neuroprotection where TAT-CBD3 failed. Neither peptide altered surface trafficking of NMDARs. Neuroprotection conferred by MTS-CBD3 peptide is likely due to its increased uptake coupled with decreased efflux when compared to TAT-CBD3. Overall, our results demonstrate that altering CPPs can bestow differential neuroprotective potential onto the CBD3 cargo.

Discovery and characterization of small molecules that target the GTPase Ral

The Ras-like GTPases RalA and RalB are important drivers of tumour growth and metastasis. Chemicals that block Ral function would be valuable as research tools and for cancer therapeutics. Here we used protein structure analysis and virtual screening to identify drug-like molecules that bind to a site on the GDP-bound form of Ral. The compounds RBC6, RBC8 and RBC10 inhibited the binding of Ral to its effector RALBP1, as well as inhibiting Ral-mediated cell spreading of murine embryonic fibroblasts and anchorage-independent growth of human cancer cell lines. The binding of the RBC8 derivative BQU57 to RalB was confirmed by isothermal titration calorimetry, surface plasmon resonance and (1)H-(15)N transverse relaxation-optimized spectroscopy (TROSY) NMR spectroscopy. RBC8 and BQU57 show selectivity for Ral relative to the GTPases Ras and RhoA and inhibit tumour xenograft growth to a similar extent to the depletion of Ral using RNA interference. Our results show the utility of structure-based discovery for the development of therapeutics for Ral-dependent cancers.

Fungi of Delhi. XII. Chaetomium lawransamesii sp. n

<i>Chaetomium lawransamesii</i> has been described as a new species. This is characterised in possessing bigger fusiform ascospores and myceloid terminal hair on its perithecia. During our studies on the ecology and taxonomy of plant surface fungi, we have isolated several forms isolated. This paper describes a no w species of <i>Chaetomium</i> which differes from all the known species possessing fusiform ascospores (L o d h a 1964; Rai, Mukerji 1962). It has characteristic long myceloid hairs on its body. This form has been named as <i>C. lawransamesii</i> in honour of late Dr Lawrence M. Ames.

The functionalized amino acid (S)-Lacosamide subverts CRMP2-mediated tubulin polymerization to prevent constitutive and activity-dependent increase in neurite outgrowth

Activity-dependent neurite outgrowth is a highly complex, regulated process with important implications for neuronal circuit remodeling in development as well as in seizure-induced sprouting in epilepsy. Recent work has linked outgrowth to collapsin response mediator protein 2 (CRMP2), an intracellular phosphoprotein originally identified as axon guidance and growth cone collapse protein. The neurite outgrowth promoting function of CRMP2 is regulated by its phosphorylation state. In this study, depolarization (potassium chloride)-driven activity increased the level of active CRMP2 by decreasing its phosphorylation by GSK3β via a reduction in priming by Cdk5. To determine the contribution of CRMP2 in activity-driven neurite outgrowth, we screened a limited set of compounds for their ability to reduce neurite outgrowth but not modify voltage-gated sodium channel (VGSC) biophysical properties. This led to the identification of (S)-lacosamide ((S)-LCM), a stereoisomer of the clinically used antiepileptic drug (R)-LCM (Vimpat®), as a novel tool for preferentially targeting CRMP2-mediated neurite outgrowth. Whereas (S)-LCM was ineffective in targeting VGSCs, the presumptive pharmacological targets of (R)-LCM, (S)-LCM was more efficient than (R)-LCM in subverting neurite outgrowth. Biomolecular interaction analyses revealed that (S)-LCM bound to wildtype CRMP2 with low micromolar affinity, similar to (R)-LCM. Through the use of this novel tool, the activity-dependent increase in neurite outgrowth observed following depolarization was characterized to be reliant on CRMP2 function. Knockdown of CRMP2 by siRNA in cortical neurons resulted in reduced CRMP2-dependent neurite outgrowth; incubation with (S)-LCM phenocopied this effect. Other CRMP2-mediated processes were unaffected. (S)-LCM subverted neurite outgrowth not by affecting the canonical CRMP2-tubulin association but rather by impairing the ability of CRMP2 to promote tubulin polymerization, events that are perfunctory for neurite outgrowth. Taken together, these results suggest that changes in the phosphorylation state of CRMP2 are a major contributing factor in activity-dependent regulation of neurite outgrowth.

Mapping CRMP3 domains involved in dendrite morphogenesis and voltage-gated calcium channel regulation

Although hippocampal neurons are well-distinguished by the morphological characteristics of their dendrites and their structural plasticity, the mechanisms involved in regulating their neurite initiation, dendrite growth, network formation and remodeling are still largely unknown, in part because the key molecules involved remain elusive. Identifying new dendrite-active cues could uncover unknown molecular mechanisms that would add significant understanding to the field and possibly lead to the development of novel neuroprotective therapy because these neurons are impaired in many neuropsychiatric disorders. In our previous studies, we deleted the gene encoding CRMP3 in mice and identified the protein as a new endogenous signaling molecule that shapes diverse features of the hippocampal pyramidal dendrites without affecting axon morphology. We also found that CRMP3 protects dendrites against dystrophy induced by prion peptide PrP(106-126). Here, we report that CRMP3 has a profound influence on neurite initiation and dendrite growth of hippocampal neurons in vitro. Our deletional mapping revealed that the C-terminus of CRMP3 probably harbors its dendritogenic capacity and supports an active transport mechanism. By contrast, overexpression of the C-terminal truncated CRMP3 phenocopied the effect of CRMP3 gene deletion with inhibition of neurite initiation or decrease in dendrite complexity, depending on the stage of cell development. In addition, this mutant inhibited the activity of CRMP3, in a similar manner to siRNA. Voltage-gated calcium channel inhibitors prevented CRMP3-induced dendritic growth and somatic Ca(2+) influx in CRMP3-overexpressing neurons was augmented largely via L-type channels. These results support a link between CRMP3-mediated Ca(2+) influx and CRMP3-mediated dendritic growth in hippocampal neurons.