Publications by authors named "Rajesh Khanna"

182 Publications

Non-SUMOylated CRMP2 decreases Na1.7 currents via the endocytic proteins Numb, Nedd4-2 and Eps15.

Mol Brain 2021 01 21;14(1):20. Epub 2021 Jan 21.

Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA.

Voltage-gated sodium channels are key players in neuronal excitability and pain signaling. Functional expression of the voltage-gated sodium channel Na1.7 is under the control of SUMOylated collapsin response mediator protein 2 (CRMP2). When not SUMOylated, CRMP2 forms a complex with the endocytic proteins Numb, the epidermal growth factor receptor pathway substrate 15 (Eps15), and the E3 ubiquitin ligase Nedd4-2 to promote clathrin-mediated endocytosis of Na1.7. We recently reported that CRMP2 SUMO-null knock-in (CRMP2) female mice have reduced Na1.7 membrane localization and currents in their sensory neurons. Preventing CRMP2 SUMOylation was sufficient to reverse mechanical allodynia in CRMP2 female mice with neuropathic pain. Here we report that inhibiting clathrin assembly in nerve-injured male CRMP2 mice precipitated mechanical allodynia in mice otherwise resistant to developing persistent pain. Furthermore, Numb, Nedd4-2 and Eps15 expression was not modified in basal conditions in the dorsal root ganglia (DRG) of male and female CRMP2 mice. Finally, silencing these proteins in DRG neurons from female CRMP2 mice, restored the loss of sodium currents. Our study shows that the endocytic complex composed of Numb, Nedd4-2 and Eps15, is necessary for non-SUMOylated CRMP2-mediated internalization of sodium channels in vivo.
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http://dx.doi.org/10.1186/s13041-020-00714-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7819318PMC
January 2021

Targeting T-type/CaV3.2 channels for chronic pain.

Transl Res 2021 Jan 7. Epub 2021 Jan 7.

Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, Arizona; Comprehensive Pain and Addiction Center, The University of Arizona, Tucson, Arizona; Regulonix LLC, Tucson, Arizona. Electronic address:

T-type calcium channels regulate neuronal excitability and are important contributors of pain processing. CaV3.2 channels are the major isoform expressed in nonpeptidergic and peptidergic nociceptive neurons and are emerging as promising targets for pain treatment. Numerous studies have shown that CaV3.2 expression and/or activity are significantly increased in spinal dorsal horn and in dorsal root ganglia neurons in different inflammatory and neuropathic pain models. Pharmacological campaigns to inhibit the functional expression of CaV3.2 for treatment of pain have focused on the development of direct channel blockers, but none have produced lead candidates. Targeting the proteins that regulate the trafficking or transcription, and the ones that modify the channels via post-translational modifications are alternative means to regulate expression and function of CaV3.2 channels and hence to develop new drugs to control pain. Here we synthesize data supporting a role for CaV3.2 in numerous pain modalities and then discuss emerging opportunities for the indirect targeting of CaV3.2 channels.
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http://dx.doi.org/10.1016/j.trsl.2021.01.002DOI Listing
January 2021

Comparison of quinazoline and benzoylpyrazoline chemotypes targeting the CaVα-β interaction as antagonists of the N-type CaV2.2 channel.

Channels (Austin) 2021 Dec;15(1):128-135

Department of Pharmacology, College of Medicine, The University of Arizona , Tucson, AZ, USA.

Structural studies with an α subunit fragment of voltage-gated calcium (CaV) channels in complex with the CaVβ subunits revealed a high homology between the various CaVα-β subunits, predicting that targeting of this interface would result in nonselective compounds. Despite this likelihood, my laboratory initiated a rational structure-based screening campaign focusing on "hot spots" on the alpha interacting domain (AID) of the CaVβ2a subunits and identified the small molecule 2-(3,5-dimethylisoxazol-4-yl)-N-((4-((3-phenylpropyl)amino)quinazolin-2-yl)methyl)acetamide ( ) which selectively targeted the interface between the N-type calcium (CaV2.2) channel and CaVβ. (i) specifically bound to CaVβ2a; (ii) inhibited CaVβ2 's interaction with CaV.2-AID; (iii) inhibited CaV2.2 currents in sensory neurons; (iv) inhibited pre-synaptic localization of CaV2.2 ; and (v) inhibited spinal neurotransmission, which resulted in decreased neurotransmitter release. was anti-nociceptive in naïve rats and reversed mechanical allodynia and thermal hyperalgesia in rodent models of acute, neuropathic, and genetic pain. In structure-activity relationship (SAR) studies focused on improving binding affinity of , another compound (BTT-369), a benzoyl-3,4-dihydro-1'H,2 H-3,4'-bipyrazole class of compounds, was reported by Chen and colleagues, based on work conducted in my laboratory beginning in 2008. BTT-369 contains tetraaryldihydrobipyrazole scaffold - a chemotype featuring phenyl groups known to be significantly metabolized, lower the systemic half-life, and increase the potential for toxicity. Furthermore, the benzoylpyrazoline skeleton in BTT-369 is patented across multiple therapeutic indications. Prior to embarking on an extensive optimization campaign of , we performed a head-to-head comparison of the two compounds. We conclude that is superior to BTT-369 for on-target efficacy, setting the stage for SAR studies to improve on for the development of novel pain therapeutics.
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http://dx.doi.org/10.1080/19336950.2020.1863595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7808423PMC
December 2021

Evaluation of the effects of the T-type calcium channel enhancer SAK3 in a rat model of TAF1 deficiency.

Neurobiol Dis 2021 Feb 24;149:105224. Epub 2020 Dec 24.

Department of Pathology, University of Arizona College of Medicine and College of Pharmacy, Tucson, AZ, USA. Electronic address:

The TATA-box binding protein associated factor 1 (TAF1) is part of the TFIID complex that plays a key role during the initiation of transcription. Variants of TAF1 are associated with neurodevelopmental disorders. Previously, we found that CRISPR/Cas9 based editing of the TAF1 gene disrupts the morphology of the cerebral cortex and blunts the expression as well as the function of the CaV3.1 (T-type) voltage gated calcium channel. Here, we tested the efficacy of SAK3 (ethyl 8'-methyl-2', 4-dioxo-2-(piperidin-1-yl)-2'H-spiro [cyclopentane-1, 3'-imidazo [1, 2-a] pyridine]-2-ene-3-carboxylate), a T-type calcium channel enhancer, in an animal model of TAF1 intellectual disability (ID) syndrome. At post-natal day 3, rat pups were subjected to intracerebroventricular (ICV) injection of either gRNA-control or gRNA-TAF1 CRISPR/Cas9 viruses. At post-natal day 21, the rat pups were given SAK3 (0.25 mg/kg, p.o.) or vehicle for 14 days (i.e. till post-natal day 35) and then subjected to behavioral, morphological, and molecular studies. Oral administration of SAK3 (0.25 mg/kg, p.o.) significantly rescued locomotion abnormalities associated with TAF1 gene editing. SAK3 treatment prevented the loss of cortical neurons and GFAP-positive astrocytes observed after TAF1 gene editing. In addition, SAK3 protected cells from apoptosis. SAK3 also restored the Brain-derived neurotrophic factor/protein kinase B/Glycogen Synthase Kinase 3 Beta (BDNF/AKT/GSK3β) signaling axis in TAF1 edited animals. Finally, SAK3 normalized the levels of three GSK3β substrates - CaV3.1, FOXP2, and CRMP2. We conclude that the T-type calcium channel enhancer SAK3 is beneficial against the deleterious effects of TAF1 gene-editing, in part, by stimulating the BDNF/AKT/GSK3β signaling pathway.
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http://dx.doi.org/10.1016/j.nbd.2020.105224DOI Listing
February 2021

Intellectual disability: dendritic anomalies and emerging genetic perspectives.

Acta Neuropathol 2021 02 23;141(2):139-158. Epub 2020 Nov 23.

Department of Psychiatry and Behavioral Health, The Ohio State University, Columbus, OH, 43210, USA.

Intellectual disability (ID) corresponds to several neurodevelopmental disorders of heterogeneous origin in which cognitive deficits are commonly associated with abnormalities of dendrites and dendritic spines. These histological changes in the brain serve as a proxy for underlying deficits in neuronal network connectivity, mostly a result of genetic factors. Historically, chromosomal abnormalities have been reported by conventional karyotyping, targeted fluorescence in situ hybridization (FISH), and chromosomal microarray analysis. More recently, cytogenomic mapping, whole-exome sequencing, and bioinformatic mining have led to the identification of novel candidate genes, including genes involved in neuritogenesis, dendrite maintenance, and synaptic plasticity. Greater understanding of the roles of these putative ID genes and their functional interactions might boost investigations into determining the plausible link between cellular and behavioral alterations as well as the mechanisms contributing to the cognitive impairment observed in ID. Genetic data combined with histological abnormalities, clinical presentation, and transgenic animal models provide support for the primacy of dysregulation in dendrite structure and function as the basis for the cognitive deficits observed in ID. In this review, we highlight the importance of dendrite pathophysiology in the etiologies of four prototypical ID syndromes, namely Down Syndrome (DS), Rett Syndrome (RTT), Digeorge Syndrome (DGS) and Fragile X Syndrome (FXS). Clinical characteristics of ID have also been reported in individuals with deletions in the long arm of chromosome 10 (the q26.2/q26.3), a region containing the gene for the collapsin response mediator protein 3 (CRMP3), also known as dihydropyrimidinase-related protein-4 (DRP-4, DPYSL4), which is involved in dendritogenesis. Following a discussion of clinical and genetic findings in these syndromes and their preclinical animal models, we lionize CRMP3/DPYSL4 as a novel candidate gene for ID that may be ripe for therapeutic intervention.
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http://dx.doi.org/10.1007/s00401-020-02244-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7855540PMC
February 2021

Green Light Exposure Improves Pain and Quality of Life in Fibromyalgia Patients: A Preliminary One-Way Crossover Clinical Trial.

Pain Med 2021 Feb;22(1):118-130

Departments of Pharmacology, University of Arizona, Tucson, Arizona, USA.

Objective: Fibromyalgia is a functional pain disorder in which patients suffer from widespread pain and poor quality of life. Fibromyalgia pain and its impact on quality of life are not effectively managed with current therapeutics. Previously, in a preclinical rat study, we demonstrated that exposure to green light-emitting diodes (GLED) for 8 hours/day for 5 days resulted in antinociception and reversal of thermal and mechanical hypersensitivity associated with models of injury-related pain. Given the safety of GLED and the ease of its use, our objective is to administer GLED as a potential therapy to patients with fibromyalgia.

Design: One-way crossover clinical trial.

Setting: United States.

Method: We enrolled 21 adult patients with fibromyalgia recruited from the University of Arizona chronic pain clinic who were initially exposed to white light-emitting diodes and then were crossed over to GLED for 1 to 2 hours daily for 10 weeks. Data were collected by using paper surveys.

Results: When patients were exposed to GLED, but not white light-emitting diodes, they reported a significant reduction in average pain intensity on the 10-point numeric pain scale. Secondary outcomes were assessed by using the EQ-5D-5L survey, Short-Form McGill Pain Questionnaire, and Fibromyalgia Impact Questionnaire and were also significantly improved in patients exposed to GLED. GLED therapy was not associated with any measured side effects in these patients.

Conclusion: Although the mechanism by which GLED elicits pain reduction is currently being studied, these results supporting its efficacy and safety merit a larger clinical trial.
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http://dx.doi.org/10.1093/pm/pnaa329DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7861466PMC
February 2021

SARS-CoV-2 spike protein co-opts VEGF-A/neuropilin-1 receptor signaling to induce analgesia.

Pain 2021 01;162(1):243-252

Departments of Pharmacology, and.

Global spread of severe acute respiratory syndrome coronavirus 2 continues unabated. Binding of severe acute respiratory syndrome coronavirus 2's spike protein to host angiotensin-converting enzyme 2 triggers viral entry, but other proteins may participate, including the neuropilin-1 receptor (NRP-1). Because both spike protein and vascular endothelial growth factor-A (VEGF-A)-a pronociceptive and angiogenic factor, bind NRP-1, we tested whether spike could block VEGF-A/NRP-1 signaling. VEGF-A-triggered sensory neuron firing was blocked by spike protein and NRP-1 inhibitor EG00229. Pronociceptive behaviors of VEGF-A were similarly blocked through suppression of spontaneous spinal synaptic activity and reduction of electrogenic currents in sensory neurons. Remarkably, preventing VEGF-A/NRP-1 signaling was antiallodynic in a neuropathic pain model. A "silencing" of pain through subversion of VEGF-A/NRP-1 signaling may underlie increased disease transmission in asymptomatic individuals.
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http://dx.doi.org/10.1097/j.pain.0000000000002097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7737878PMC
January 2021

Sculpting Dendritic Spines during Initiation and Maintenance of Neuropathic Pain.

J Neurosci 2020 09;40(40):7578-7589

Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724

Accumulating evidence has established a firm role for synaptic plasticity in the pathogenesis of neuropathic pain. Recent advances have highlighted the importance of dendritic spine remodeling in driving synaptic plasticity within the CNS. Identifying the molecular players underlying neuropathic pain induced structural and functional maladaptation is therefore critical to understanding its pathophysiology. This process of dynamic reorganization happens in unique phases that have diverse pathologic underpinnings in the initiation and maintenance of neuropathic pain. Recent evidence suggests that pharmacological targeting of specific proteins during distinct phases of neuropathic pain development produces enhanced antinociception. These findings outline a potential new paradigm for targeted treatment and the development of novel therapies for neuropathic pain. We present a concise review of the role of dendritic spines in neuropathic pain and outline the potential for modulation of spine dynamics by targeting two proteins, srGAP3 and Rac1, critically involved in the regulation of the actin cytoskeleton.
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http://dx.doi.org/10.1523/JNEUROSCI.1664-20.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7531544PMC
September 2020

In silico identification and validation of inhibitors of the interaction between neuropilin receptor 1 and SARS-CoV-2 Spike protein.

bioRxiv 2020 Sep 23. Epub 2020 Sep 23.

Neuropilin-1 (NRP-1) is a multifunctional transmembrane receptor for ligands that affect developmental axonal growth and angiogenesis. In addition to a role in cancer, NRP-1 is a reported entry point for several viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of coronavirus disease 2019 (COVID-19). The furin cleavage product of SARS-CoV-2 Spike protein takes advantage of the vascular endothelial growth factor A (VEGF-A) binding site on NRP-1 which accommodates a polybasic stretch ending in a C-terminal arginine. This site has long been a focus of drug discovery efforts for cancer therapeutics. We recently showed that interruption of the VEGF-A/NRP-1 signaling pathway ameliorates neuropathic pain and hypothesize that interference of this pathway by SARS-CoV-2 spike protein interferes with pain signaling. Here, we report hits from a small molecule and natural product screen of nearly 0.5 million compounds targeting the VEGF-A binding site on NRP-1. We identified nine chemical series with lead- or drug-like physico-chemical properties. Using an ELISA, we demonstrate that six compounds disrupt VEGF-A-NRP-1 binding more effectively than EG00229, a known NRP-1 inhibitor. Secondary validation in cells revealed that almost all tested compounds inhibited VEGF-A triggered VEGFR2 phosphorylation. Two compounds displayed robust inhibition of a recombinant vesicular stomatitis virus protein that utilizes the SARS-CoV-2 Spike for entry and fusion. These compounds represent a first step in a renewed effort to develop small molecule inhibitors of the VEGF-A/NRP-1 signaling for the treatment of neuropathic pain and cancer with the added potential of inhibiting SARS-CoV-2 virus entry.
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http://dx.doi.org/10.1101/2020.09.22.308783DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7523098PMC
September 2020

Synaptic zinc inhibition of NMDA receptors depends on the association of GluN2A with the zinc transporter ZnT1.

Sci Adv 2020 Jul 3;6(27). Epub 2020 Jul 3.

Department of Otolaryngology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.

The NMDA receptor (NMDAR) is inhibited by synaptically released zinc. This inhibition is thought to be the result of zinc diffusion across the synaptic cleft and subsequent binding to the extracellular domain of the NMDAR. However, this model fails to incorporate the observed association of the highly zinc-sensitive NMDAR subunit GluN2A with the postsynaptic zinc transporter ZnT1, which moves intracellular zinc to the extracellular space. Here, we report that disruption of ZnT1-GluN2A association by a cell-permeant peptide strongly reduced NMDAR inhibition by synaptic zinc in mouse dorsal cochlear nucleus synapses. Moreover, synaptic zinc inhibition of NMDARs required postsynaptic intracellular zinc, suggesting that cytoplasmic zinc is transported by ZnT1 to the extracellular space in close proximity to the NMDAR. These results challenge a decades-old dogma on how zinc inhibits synaptic NMDARs and demonstrate that presynaptic release and a postsynaptic transporter organize zinc into distinct microdomains to modulate NMDAR neurotransmission.
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http://dx.doi.org/10.1126/sciadv.abb1515DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458442PMC
July 2020

Targeted disruption of Kv2.1-VAPA association provides neuroprotection against ischemic stroke in mice by declustering Kv2.1 channels.

Sci Adv 2020 Jul 1;6(27). Epub 2020 Jul 1.

Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.

Kv2.1 channels mediate cell death-enabling loss of cytosolic potassium in neurons following plasma membrane insertion at somatodendritic clusters. Overexpression of the carboxyl terminus (CT) of the cognate channel Kv2.2 is neuroprotective by disrupting Kv2.1 surface clusters. Here, we define a seven-amino acid declustering domain within Kv2.2 CT (DP-2) and demonstrate its neuroprotective efficacy in a murine ischemia-reperfusion model. TAT-DP-2, a membrane-permeable derivative, induces Kv2.1 surface cluster dispersal, prevents post-injurious pro-apoptotic potassium current enhancement, and is neuroprotective in vitro by disrupting the association of Kv2.1 with VAPA. TAT-DP-2 also induces Kv2.1 cluster dispersal in vivo in mice, reducing infarct size and improving long-term neurological function following stroke. We suggest that TAT-DP-2 induces Kv2.1 declustering by disrupting Kv2.1-VAPA association and scaffolding sites required for the membrane insertion of Kv2.1 channels following injury. We present the first evidence of targeted disruption of Kv2.1-VAPA association as a neuroprotective strategy following brain ischemia.
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http://dx.doi.org/10.1126/sciadv.aaz8110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458461PMC
July 2020

Evaluation of green light exposure on headache frequency and quality of life in migraine patients: A preliminary one-way cross-over clinical trial.

Cephalalgia 2021 Feb 9;41(2):135-147. Epub 2020 Sep 9.

Department of Anesthesiology, College of Medicine, University of Arizona, Tucson, AZ, USA.

Background: Pharmacological management of migraine can be ineffective for some patients. We previously demonstrated that exposure to green light resulted in antinociception and reversal of thermal and mechanical hypersensitivity in rodent pain models. Given the safety of green light emitting diodes, we evaluated green light as a potential therapy in patients with episodic or chronic migraine.

Material And Methods: We recruited (29 total) patients, of whom seven had episodic migraine and 22 had chronic migraine. We used a one-way cross-over design consisting of exposure for 1-2 hours daily to white light emitting diodes for 10 weeks, followed by a 2-week washout period followed by exposure for 1-2 hours daily to green light emitting diodes for 10 weeks. Patients were allowed to continue current therapies and to initiate new treatments as directed by their physicians. Outcomes consisted of patient-reported surveys. The primary outcome measure was the number of headache days per month. Secondary outcome measures included patient-reported changes in the intensity and frequency of the headaches over a two-week period and other quality of life measures including ability to fall and stay asleep, and ability to perform work. Changes in pain medications were obtained to assess potential reduction.

Results: When seven episodic migraine and 22 chronic migraine patients were analyzed as separate cohorts, white light emitting diodes produced no significant change in headache days in either episodic migraine or chronic migraine patients. Combining data from the episodic migraine and chronic migraine groups showed that white light emitting diodes produced a small, but statistically significant reduction in headache days from (days ± SEM) 18.2 ± 1.8 to 16.5 ± 2.01 days. Green light emitting diodes resulted in a significant decrease in headache days from 7.9 ± 1.6 to 2.4 ± 1.1 and from 22.3 ± 1.2 to 9.4 ± 1.6 in episodic migraine and chronic migraine patients, respectively. While some improvement in secondary outcomes was observed with white light emitting diodes, more secondary outcomes with significantly greater magnitude including assessments of quality of life, Short-Form McGill Pain Questionnaire, Headache Impact Test-6, and Five-level version of the EuroQol five-dimensional survey without reported side effects were observed with green light emitting diodes. Conclusions regarding pain medications reduction with green light emitting diode exposure were not possible. No side effects of light therapy were reported. None of the patients in the study reported initiation of new therapies.

Discussion: Green light emitting diodes significantly reduced the number of headache days in people with episodic migraine or chronic migraine. Additionally, green light emitting diodes significantly improved multiple secondary outcome measures including quality of life and intensity and duration of the headache attacks. As no adverse events were reported, green light emitting diodes may provide a treatment option for those patients who prefer non-pharmacological therapies or may be considered in complementing other treatment strategies. Limitations of this study are the small number of patients evaluated. The positive data obtained support implementation of larger clinical trials to determine possible effects of green light emitting diode therapy.This study is registered with clinicaltrials.gov under NCT03677206.
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http://dx.doi.org/10.1177/0333102420956711DOI Listing
February 2021

SARS-CoV-2 Spike protein co-opts VEGF-A/Neuropilin-1 receptor signaling to induce analgesia.

bioRxiv 2020 Aug 24. Epub 2020 Aug 24.

Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, Arizona, 85724 United States of America.

Global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues unabated. Binding of SARS-CoV-2's Spike protein to host angiotensin converting enzyme 2 triggers viral entry, but other proteins may participate, including neuropilin-1 receptor (NRP-1). As both Spike protein and vascular endothelial growth factor-A (VEGF-A) - a pro-nociceptive and angiogenic factor, bind NRP-1, we tested if Spike could block VEGF-A/NRP-1 signaling. VEGF-A-triggered sensory neuronal firing was blocked by Spike protein and NRP-1 inhibitor EG00229. Pro-nociceptive behaviors of VEGF-A were similarly blocked via suppression of spontaneous spinal synaptic activity and reduction of electrogenic currents in sensory neurons. Remarkably, preventing VEGF-A/NRP-1 signaling was antiallodynic in a neuropathic pain model. A 'silencing' of pain via subversion of VEGF-A/NRP-1 signaling may underlie increased disease transmission in asymptomatic individuals.
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http://dx.doi.org/10.1101/2020.07.17.209288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7457601PMC
August 2020

Mutant huntingtin does not cross the mitochondrial outer membrane.

Hum Mol Genet 2020 Oct;29(17):2962-2975

Department of Pharmacology and Toxicology.

Mutant huntingtin (mHTT) is associated with mitochondria, but the exact mitochondrial location of mHTT has not been definitively established. Recently, it was reported that mHTT is present in the intermembrane space and inhibits mitochondrial protein import by interacting with TIM23, a major component of mitochondrial protein import machinery, but evidence for functional ramifications were not provided. We assessed mHTT location using synaptic and nonsynaptic mitochondria isolated from brains of YAC128 mice and subjected to alkali treatment or limited trypsin digestion. Mitochondria were purified either with discontinuous Percoll gradient or with anti-TOM22-conjugated iron microbeads. We also used mitochondria isolated from postmortem brain tissues of unaffected individuals and HD patients. Our results demonstrate that mHTT is located on the cytosolic side of the mitochondrial outer membrane (MOM) but does not cross it. This refutes the hypothesis that mHTT may interact with TIM23 and inhibit mitochondrial protein import. The levels of expression of nuclear-encoded, TIM23-transported mitochondrial proteins ACO2, TUFM, IDH3A, CLPP and mitochondrially encoded and synthesized protein mtCO1 were similar in mitochondria from YAC128 mice and their wild-type littermates as well as in mitochondria from postmortem brain tissues of unaffected individuals and HD patients, supporting the lack of deficit in mitochondrial protein import. Regardless of purification technique, mitochondria from YAC128 and WT mice had similar respiratory activities and mitochondrial membrane potentials. Thus, our data argue against mHTT crossing the MOM and entering into the mitochondrial intermembrane space, making it highly unlikely that mHTT interacts with TIM23 and inhibits protein import in intact mitochondria.
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http://dx.doi.org/10.1093/hmg/ddaa185DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566381PMC
October 2020

Collapsin Response Mediator Proteins: Novel Targets for Alzheimer's Disease.

J Alzheimers Dis 2020 ;77(3):949-960

Institute for Behavioral Medicine Research, Wexner Medical Center, The Ohio State University, Columbus, OH, USA.

Numerous experimental and postmortem studies have increasingly reported dystrophic axons and dendrites, and alterations of dendritic spine morphology and density in the hippocampus as prominent changes in the early stages of Alzheimer's disease (AD). Furthermore, these alterations tend to correlate well with the progressive cognitive decline observed in AD. For these reasons, and because these neurite structures have a capacity to re-grow, re-establish lost connections, and are critical for learning and memory, there is compelling evidence to suggest that therapeutic interventions aimed at preventing their degradation or promoting their regrowth may hold tremendous promise in preventing the progression of AD. In this regard, collapsin response mediator proteins (CRMPs), a family of phosphoproteins playing a major role in axon guidance and dendritic growth, are especially interesting. The roles these proteins play in neurons and immune cells are reviewed here.
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http://dx.doi.org/10.3233/JAD-200721DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7579750PMC
January 2020

The role of cyclin-dependent kinase 5 in neuropathic pain.

Pain 2020 12;161(12):2674-2689

Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ, United States.

The chronification of pain can be attributed to changes in membrane receptors and channels underlying neuronal plasticity and signal transduction largely within nociceptive neurons that initiate and maintain pathological pain states. These proteins are subject to dynamic modification by posttranslational modifications, creating a code that controls protein function in time and space. Phosphorylation is an important posttranslational modification that affects ∼30% of proteins in vivo. Increased phosphorylation of various nociceptive ion channels and of their modulators underlies sensitization of different pain states. Cyclin-dependent kinases are proline-directed serine/threonine kinases that impact various biological and cellular systems. Cyclin-dependent kinase 5 (Cdk5), one member of this kinase family, and its activators p35 and p39 are expressed in spinal nerves, dorsal root ganglia, and the dorsal horn of the spinal cord. In neuropathic pain conditions, expression and/or activity of Cdk5 is increased, implicating Cdk5 in nociception. Experimental evidence suggests that Cdk5 is regulated through its own phosphorylation, through increasing p35's interaction with Cdk5, and through cleavage of p35 into p25. This narrative review discusses the molecular mechanisms of Cdk5-mediated regulation of target proteins involved in neuropathic pain. We focus on Cdk5 substrates that have been linked to nociceptive pathways, including channels (eg, transient receptor potential cation channel and voltage-gated calcium channel), proteins involved in neurotransmitter release (eg, synaptophysin and collapsin response mediator protein 2), and receptors (eg, glutamate, purinergic, and opioid). By altering the phosphoregulatory "set point" of proteins involved in pain signaling, Cdk5 thus appears to be an attractive target for treating neuropathic pain conditions.
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http://dx.doi.org/10.1097/j.pain.0000000000002027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7669638PMC
December 2020

Putative roles of SLC7A5 (LAT1) transporter in pain.

Neurobiol Pain 2020 Aug-Dec;8:100050. Epub 2020 Jun 30.

Department of Pharmacology, University of Arizona, United States.

Large amino acid transporter 1 (LAT1), also known as SLC7A5, is an essential amino acid transporter that forms a heterodimeric complex with the glycoprotein cell-surface antigen heavy chain (4F2hc (CD98, SLC3A2)). Within nociceptive pathways, LAT1 is expressed in the dorsal root ganglia and spinal cord. Although LAT1 expression is upregulated following spinal cord injury, little is known about LAT1 in neuropathic pain. To date, only circumstantial evidence supports LAT1/4F2hc's role in pain. Notably, LAT1's expression and regulation link it to key cell types and pathways implicated in pain. Transcriptional regulation of LAT1 expression occurs via the Wnt/frizzled/β-catenin signal transduction pathway, which has been shown to be involved in chronic pain. The LAT1/4F2hc complex may also be involved in pain pathways related to T- and B-cells. LAT1's expression induces activation of the mammalian target of rapamycin (mTOR) signaling axis, which is involved in inflammation and neuropathic pain. Similarly, hypoxia and cancer induce activation of hypoxia-inducible factor 2 alpha, promoting not only LAT1's expression but also mTORC1's activation. Perhaps the strongest evidence linking LAT1 to pain is its interactions with key voltage-gated ion channels connected to nociception, namely the voltage-gated potassium channels Kv1.1 and Kv1.2 and the voltage-gated sodium channel Nav1.7. Through functional regulation of these channels, LAT1 may play a role in governing the excitatory to inhibitory ratio which is altered in chronic neuropathic pain states. Remarkably, the most direct role for LAT1 in pain is to mediate the influx of gabapentin and pregabalin, two first-line neuropathic pain drugs, that indirectly inhibit high voltage-activated calcium channel auxiliary subunit α2δ-1. In this review, we discuss the expression, regulation, relevant signaling pathways, and protein interactions of LAT1 that may link it to the development and/or maintenance of pain. We hypothesize that LAT1 expressed in nociceptive pathways may be a viable new target in pain.
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http://dx.doi.org/10.1016/j.ynpai.2020.100050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7369351PMC
June 2020

Druggability of CRMP2 for Neurodegenerative Diseases.

ACS Chem Neurosci 2020 09 4;11(17):2492-2505. Epub 2020 Aug 4.

BrightRock Path, LLC, Tucson, Arizona 85704, United States.

Collapsin response mediator proteins (CRMPs) are ubiquitously expressed phosphoproteins that coordinate cytoskeletal formation and regulate cellular division, migration, polarity, and synaptic connection. CRMP2, the most studied of the five family members, is best known for its affinity for tubulin heterodimers and function in regulating the microtubule network. Accumulating evidence has also demonstrated a key role for CRMP2 in trafficking of voltage- and ligand-gated ion channels. These functions are tightly regulated by post-translational modifications including phosphorylation and SUMOylation (addition of a small ubiquitin like modifier). Over the past decade, it has become increasingly clear that dysregulated post-translational modifications of CRMP2 contribute to the pathomechanisms of diverse diseases, including cancer, neurodegenerative diseases, chronic pain, and bipolar disorder. Here, we review the discovery, functions, and current putative preclinical and clinical therapeutics targeting CRMP2. These potential therapeutics include CRMP2-based peptides that inhibit protein-protein interactions and small-molecule compounds. Capitalizing on the availability of structural information, we identify druggable pockets on CRMP2 and predict binding modes for five known CRMP2-targeting compounds, setting the stage for optimization and de novo drug discovery targeting this multifunctional protein.
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http://dx.doi.org/10.1021/acschemneuro.0c00307DOI Listing
September 2020

The investigation of the T-type calcium channel enhancer SAK3 in an animal model of TAF1 intellectual disability syndrome.

Neurobiol Dis 2020 09 2;143:105006. Epub 2020 Jul 2.

Department of Pathology, University of Arizona College of Medicine, College of Pharmacy, Tucson, AZ, USA. Electronic address:

T-type calcium channels, in the central nervous system, are involved in the pathogenesis of many neurodegenerative diseases, including TAF1 intellectual disability syndrome (TAF1 ID syndrome). Here, we evaluated the efficacy of a novel T-type Ca channel enhancer, SAK3 (ethyl 8'-methyl-2', 4-dioxo-2-(piperidin-1-yl)-2'H-spiro [cyclopentane-1, 3'-imidazo [1, 2-a] pyridine]-2-ene-3-carboxylate) in an animal model of TAF1 ID syndrome. At post-natal day 3, rat pups were subjected to intracerebroventricular (ICV) injection of either gRNA-control or gRNA-TAF1 CRISPR/Cas9 viruses. At post-natal day 21 animals were given SAK3 (0.25 mg/kg, p.o.) or vehicle up to post-natal day 35 (i.e. 14 days). Rats were subjected to behavioral, morphological, electrophysiological, and molecular studies. Oral administration of SAK3 (0.25 mg/kg, p.o.) significantly rescued the behavior abnormalities in beam walking test and open field test caused by TAF1 gene editing. We observed an increase in calbindin-positive Purkinje cells and GFAP-positive astrocytes as well as a decrease in IBA1-positive microglia cells in SAK3-treated animals. In addition, SAK3 protected the Purkinje and granule cells from apoptosis induced by TAF-1 gene editing. SAK3 also restored the excitatory post synaptic current (sEPSCs) in TAF1 edited Purkinje cells. Finally, SAK3 normalized the BDNF/AKT signaling axis in TAF1 edited animals. Altogether, these observations suggest that SAK3 could be a novel therapeutic agent for TAF1 ID syndrome.
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http://dx.doi.org/10.1016/j.nbd.2020.105006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7422587PMC
September 2020

Differential expression of Cdk5-phosphorylated CRMP2 following a spared nerve injury.

Mol Brain 2020 06 22;13(1):97. Epub 2020 Jun 22.

Departments of Pharmacology, University of Arizona, Tucson, AZ, 85724, USA.

Effective treatment of high-impact pain patients is one of the major stated goals of the National Pain Strategy in the United States. Identification of new targets and mechanisms underlying neuropathic pain will be critical in developing new target-specific medications for better neuropathic pain management. We recently discovered that peripheral nerve injury-induced upregulation of an axonal guidance phosphoprotein collapsin response mediator protein 2 (CRMP2) and the N-type voltage-gated calcium (CaV2.2) as well as the NaV1.7 voltage-gated sodium channel, correlates with the development of neuropathic pain. In our previous studies, we found that interfering with the phosphorylation status of CRMP2 is sufficient to confer protection from chronic pain. Here we examined the expression of CRMP2 and CRMP2 phosphorylated by cyclin-dependent kinase 5 (Cdk5, on serine residue 522 (S522)) in sciatic nerve, nerve terminals of the glabrous skin, and in select subpopulations of DRG neurons in the SNI model of neuropathic pain. By enhancing our understanding of the phosphoregulatory status of CRMP2 within DRG subpopulations, we may be in a better position to design novel pharmacological interventions for chronic pain.
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http://dx.doi.org/10.1186/s13041-020-00633-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7310452PMC
June 2020

Studies on CRMP2 SUMOylation-deficient transgenic mice identify sex-specific Nav1.7 regulation in the pathogenesis of chronic neuropathic pain.

Pain 2020 11;161(11):2629-2651

Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ, United States. Dr. Chew is now with the Duke University School of Medicine, Durham, NC, United States.

The sodium channel Nav1.7 is a master regulator of nociceptive input into the central nervous system. Mutations in this channel can result in painful conditions and produce insensitivity to pain. Despite being recognized as a "poster child" for nociceptive signaling and human pain, targeting Nav1.7 has not yet produced a clinical drug. Recent work has illuminated the Nav1.7 interactome, offering insights into the regulation of these channels and identifying potentially new druggable targets. Among the regulators of Nav1.7 is the cytosolic collapsin response mediator protein 2 (CRMP2). CRMP2, modified at lysine 374 (K374) by addition of a small ubiquitin-like modifier (SUMO), bound Nav1.7 to regulate its membrane localization and function. Corollary to this, preventing CRMP2 SUMOylation was sufficient to reverse mechanical allodynia in rats with neuropathic pain. Notably, loss of CRMP2 SUMOylation did not compromise other innate functions of CRMP2. To further elucidate the in vivo role of CRMP2 SUMOylation in pain, we generated CRMP2 K374A knock-in (CRMP2) mice in which Lys374 was replaced with Ala. CRMP2 mice had reduced Nav1.7 membrane localization and function in female, but not male, sensory neurons. Behavioral appraisal of CRMP2 mice demonstrated no changes in depressive or repetitive, compulsive-like behaviors and a decrease in noxious thermal sensitivity. No changes were observed in CRMP2 mice to inflammatory, acute, or visceral pain. By contrast, in a neuropathic model, CRMP2 mice failed to develop persistent mechanical allodynia. Our study suggests that CRMP2 SUMOylation-dependent control of peripheral Nav1.7 is a hallmark of chronic, but not physiological, neuropathic pain.
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http://dx.doi.org/10.1097/j.pain.0000000000001951DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7572581PMC
November 2020

A modulator of the low-voltage-activated T-type calcium channel that reverses HIV glycoprotein 120-, paclitaxel-, and spinal nerve ligation-induced peripheral neuropathies.

Pain 2020 11;161(11):2551-2570

Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ, United States.

The voltage-gated calcium channels CaV3.1-3.3 constitute the T-type subfamily, whose dysfunctions are associated with epilepsy, psychiatric disorders, and chronic pain. The unique properties of low-voltage-activation, faster inactivation, and slower deactivation of these channels support their role in modulation of cellular excitability and low-threshold firing. Thus, selective T-type calcium channel antagonists are highly sought after. Here, we explored Ugi-azide multicomponent reaction products to identify compounds targeting T-type calcium channel. Of the 46 compounds tested, an analog of benzimidazolonepiperidine-5bk (1-{1-[(R)-{1-[(1S)-1-phenylethyl]-1H-1,2,3,4-tetrazol-5-yl}(thiophen-3-yl)methyl]piperidin-4-yl}-2,3-dihydro-1H-1,3-benzodiazol-2-one) modulated depolarization-induced calcium influx in rat sensory neurons. Modulation of T-type calcium channels by 5bk was further confirmed in whole-cell patch clamp assays in dorsal root ganglion (DRG) neurons, where pharmacological isolation of T-type currents led to a time- and concentration-dependent regulation with a low micromolar IC50. Lack of an acute effect of 5bk argues against a direct action on T-type channels. Genetic knockdown revealed CaV3.2 to be the isoform preferentially modulated by 5bk. High voltage-gated calcium, as well as tetrodotoxin-sensitive and -resistant sodium, channels were unaffected by 5bk. 5bk inhibited spontaneous excitatory postsynaptic currents and depolarization-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices. Notably, 5bk did not bind human mu, delta, or kappa opioid receptors. 5bk reversed mechanical allodynia in rat models of HIV-associated neuropathy, chemotherapy-induced peripheral neuropathy, and spinal nerve ligation-induced neuropathy, without effects on locomotion or anxiety. Thus, 5bk represents a novel T-type modulator that could be used to develop nonaddictive pain therapeutics.
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http://dx.doi.org/10.1097/j.pain.0000000000001955DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7572723PMC
November 2020

Coordinating Synaptic Signaling with CRMP2.

Int J Biochem Cell Biol 2020 07 8;124:105759. Epub 2020 May 8.

Department of Pharmacology, College of Medicine, University of Arizona, United States; BIO5 Institute, University of Arizona, United States; The Center for Innovation in Brain Sciences, The University of Arizona Health Sciences, Tucson, Arizona, United States. Electronic address:

Synaptic transmission is a complex process, dysregulation of which underlies several neurological conditions. Collapsin response mediator protein 2 (CRMP2) is a microtubule associated protein expressed ubiquitously in the central nervous system. Identified initially in the context of Semaphorin 3A (Collapsin) induced growth cone collapse, more recent findings revealed the involvement of CRMP2 in ion channel trafficking, kinesin-dependent axonal transport and maintenance of intracellular calcium homeostasis. CRMP2 is a synaptic protein, expressed at pre- and post-synaptic sites. Interactions with proteins such as N-methyl-D-aspartate receptors, syntaxin1A as well as voltage-gated calcium and sodium channels, suggest that CRMP2 may control both the electrical and chemical components of synaptic transmission. This short review will outline the known synaptic interactions of CRMP2 and illustrate its role in synaptic transmission, thereby introducing CRMP2 as a prospective target for the pathophysiological modulation of aberrant synaptic activity.
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http://dx.doi.org/10.1016/j.biocel.2020.105759DOI Listing
July 2020

Slow coarsening in unstable liquid films under gravity on a disordered substrate.

Phys Rev E 2020 Apr;101(4-1):042801

School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.

We study the evolution of unstable liquid films via numerical solutions of the thin-film equation. The film is placed on a coated substrate with disorder. This is modeled by a random spatial variation of the relative value of the Hamaker constants for the substrate and coating. The free energy consists of (a) the van der Waals term for the substrate/coating interactions with the film and (b) a term due to gravity. This free energy admits a Maxwell double-tangent construction with two coexisting phases, i.e., "thin" and "thick" phases. In the absence of disorder, the film dewets by true morphological phase separation (MPS), i.e., the elimination of domain walls between the coexisting phases. The introduction of disorder may result in the trapping of these domain walls, with a drastic slowdown in growth kinetics. We present detailed numerical results in D=2 and D=3 to understand this slow coarsening, where D is the dimensionality of the liquid-film system.
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http://dx.doi.org/10.1103/PhysRevE.101.042801DOI Listing
April 2020

1-O-Acetylgeopyxin A, a derivative of a fungal metabolite, blocks tetrodotoxin-sensitive voltage-gated sodium, calcium channels and neuronal excitability which correlates with inhibition of neuropathic pain.

Mol Brain 2020 05 11;13(1):73. Epub 2020 May 11.

Department of Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Drive, P.O. Box 245050, Tucson, AZ, 85724, USA.

Chronic pain can be the result of an underlying disease or condition, medical treatment, inflammation, or injury. The number of persons experiencing this type of pain is substantial, affecting upwards of 50 million adults in the United States. Pharmacotherapy of most of the severe chronic pain patients includes drugs such as gabapentinoids, re-uptake blockers and opioids. Unfortunately, gabapentinoids are not effective in up to two-thirds of this population and although opioids can be initially effective, their long-term use is associated with multiple side effects. Therefore, there is a great need to develop novel non-opioid alternative therapies to relieve chronic pain. For this purpose, we screened a small library of natural products and their derivatives in the search for pharmacological inhibitors of voltage-gated calcium and sodium channels, which are outstanding molecular targets due to their important roles in nociceptive pathways. We discovered that the acetylated derivative of the ent-kaurane diterpenoid, geopyxin A, 1-O-acetylgeopyxin A, blocks voltage-gated calcium and tetrodotoxin-sensitive voltage-gated sodium channels but not tetrodotoxin-resistant sodium channels in dorsal root ganglion (DRG) neurons. Consistent with inhibition of voltage-gated sodium and calcium channels, 1-O-acetylgeopyxin A reduced reduce action potential firing frequency and increased firing threshold (rheobase) in DRG neurons. Finally, we identified the potential of 1-O-acetylgeopyxin A to reverse mechanical allodynia in a preclinical rat model of HIV-induced sensory neuropathy. Dual targeting of both sodium and calcium channels may permit block of nociceptor excitability and of release of pro-nociceptive transmitters. Future studies will harness the core structure of geopyxins for the generation of antinociceptive drugs.
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http://dx.doi.org/10.1186/s13041-020-00616-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216607PMC
May 2020

The Septum-Hippocampal Cholinergic Circuit: A Novel Pathway for Seizure Control.

Biol Psychiatry 2020 05;87(9):785-786

College of Basic Medical Science, Zhejiang Chinese Medical University, Hangzhou, China. Electronic address:

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http://dx.doi.org/10.1016/j.biopsych.2020.02.003DOI Listing
May 2020

Nasal delivery of a CRMP2-derived CBD3 adenovirus improves cognitive function and pathology in APP/PS1 transgenic mice.

Mol Brain 2020 04 9;13(1):58. Epub 2020 Apr 9.

Department of Neurology and neuroscience center, The First Hospital of Jilin University, No.1 Xinmin Street, Chaoyang District, Changchun, 130021, Jilin Province, China.

Calcium dysregulation is a key pathological event in Alzheimer's disease (AD). In studying approaches to mitigate this calcium overload, we identified the collapsin response mediator protein 2 (CRMP2), an axonal guidance protein that participates in synapse dynamics by interacting with and regulating activity of N-methyl-D-aspartate receptors (NMDARs). We further identified a 15 amino acid peptide from CRMP2 (designated CBD3, for calcium-binding domain 3), that reduced NMDAR-mediated Ca influx in cultured neurons and post-synaptic NMDAR-mediated currents in cortical slices. Whether targeting CRMP2 could be therapeutically beneficial in AD is unknown. Here, using CBD3, we tested the utility of this approach. Employing the APP/PS1 mouse model of AD which demonstrates robust pathophysiology including Aβ1-42 deposition, altered tau levels, and diminished cognitive functions, we asked if overexpression of CBD3 could rescue these events. CBD3 was engineered into an adeno-associated vector and nasally delivered into APP/PS1 mice and then biochemical (immunohistochemistry, immunoblotting), cellular (TUNEL apoptosis assays), and behavioral (Morris water maze test) assessments were performed. APP/PS1 mice administered adeno-associated virus (AAV, serotype 2) harboring CBD3 demonstrated: (i) reduced levels of Aβ1-42 and phosphorylated-tau (a marker of AD progression), (ii) reduced apoptosis in the hippocampus, and (iii) reduced cognitive decline compared with APP/PS1 mice or APP/PS1 administered a control virus. These results provide an instructive example of utilizing a peptide-based approach to unravel protein-protein interactions that are necessary for AD pathology and demonstrate the therapeutic potential of CRMP2 as a novel protein player in AD.
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http://dx.doi.org/10.1186/s13041-020-00596-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7144060PMC
April 2020

Modulation of CRMP2 via ()-Lacosamide shows therapeutic promise but is ultimately ineffective in a mouse model of CLN6-Batten disease.

Neuronal Signal 2019 06 8;3(2):NS20190001. Epub 2019 Apr 8.

Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD, U.S.A.

CLN6-Batten disease is a rare neurodegenerative disorder with no cure, characterized by accumulation of lipofuscin in the lysosome, glial activation, and neuronal death. Here we test the therapeutic efficacy of modulating collapsin response mediator protein 2 (CRMP2) activity via -N-benzy-2-acetamido-3-methoxypropionamide (()-Lacosamide) in a mouse model of CLN6-Batten disease. Promisingly, mouse neuronal cultures as well as patient fibroblasts treated with varying concentrations of ()-Lacosamide showed positive restoration of lysosomal associated deficits. However, while acute treatment enhanced glial activation in 3-month-old mutant mice, chronic treatment over several months did not improve behavioral or long-term survival outcomes. Therefore, modulation of CRMP2 activity via ()-Lacosamide alone is unlikely to be a viable therapeutic target for CLN6-Batten disease.
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http://dx.doi.org/10.1042/NS20190001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7104323PMC
June 2019

Just in time! Identification of a novel mechanism for treating PIPN.

J Physiol 2020 06 12;598(12):2283-2284. Epub 2020 May 12.

Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona.

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http://dx.doi.org/10.1113/JP279863DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7299801PMC
June 2020

Longitudinal phenotype development in a minipig model of neurofibromatosis type 1.

Sci Rep 2020 03 19;10(1):5046. Epub 2020 Mar 19.

Department of Radiology, University of Iowa, Iowa City, IA, USA.

Neurofibromatosis type 1 (NF1) is a rare, autosomal dominant disease with variable clinical presentations. Large animal models are useful to help dissect molecular mechanisms, determine relevant biomarkers, and develop effective therapeutics. Here, we studied a NF1 minipig model (NF1) for the first 12 months of life to evaluate phenotype development, track disease progression, and provide a comparison to human subjects. Through systematic evaluation, we have shown that compared to littermate controls, the NF1 model develops phenotypic characteristics of human NF1: [1] café-au-lait macules, [2] axillary/inguinal freckling, [3] shortened stature, [4] tibial bone curvature, and [5] neurofibroma. At 4 months, full body computed tomography imaging detected significantly smaller long bones in NF1 minipigs compared to controls, indicative of shorter stature. We found quantitative evidence of tibial bowing in a subpopulation of NF1 minipigs. By 8 months, an NF1 boar developed a large diffuse shoulder neurofibroma, visualized on magnetic resonance imaging, which subsequently grew in size and depth as the animal aged up to 20 months. The NF1 minipig model progressively demonstrates signature attributes that parallel clinical manifestations seen in humans and provides a viable tool for future translational NF1 research.
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http://dx.doi.org/10.1038/s41598-020-61251-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081358PMC
March 2020