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BACKGROUND: Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are rare oncogenic drivers prevalent in 0.3% of solid tumors. They are most common in salivary gland cancer (2.6%), thyroid cancer (1.6%), and soft-tissue sarcoma (1.5%). Currently, there are 2 US Food and Drug Administration-approved targeted therapies for NTRK gene fusions: larotrectinib, approved in 2018, and entrectinib, approved in 2019. To date, the real-world uptake of tyrosine receptor kinase inhibitor (TRKi) use for NTRK-positive solid tumors in academic cancer centers remains largely unknown. OBJECTIVE: To describe the demographics, clinical and genomic characteristics, and testing and treatment patterns of patients with NTRK-positive solid tumors treated at US academic cancer centers. METHODS: This was a retrospective chart review study conducted in academic cancer centers in the United States. All patients diagnosed with an NTRK fusion-positive (NTRK1, NTRK2, NTRK3) solid tumor (any stage) and who received cancer treatment at participating sites between January 1, 2012, and July 1, 2023, were included in this study. Patient demographics, clinical characteristics, genomic characteristics, NTRK testing data, and treatment patterns were collected from electronic medical records and analyzed using descriptive statistics as appropriate. RESULTS: In total, 6 centers contributed data for 55 patients with NTRK-positive tumors. The mean age was 49.3 (SD = 20.5) years, 51% patients were female, and the majority were White (78%). The median duration of time from cancer diagnosis to NTRK testing was 85 days (IQR = 44-978). At the time of NTRK testing, 64% of patients had stage IV disease, compared with 33% at cancer diagnosis. Prevalent cancer types in the overall cohort included head and neck (15%), thyroid (15%), brain (13%), lung (13%), and colorectal (11%). NTRK1 fusions were most common (45%), followed by NTRK3 (40%) and NTRK2 (15%). Across all lines of therapy, 51% of patients (n = 28) received a TRKi. Among TRKi-treated patients, 71% had stage IV disease at TRKi initiation. The median time from positive NTRK test to initiation of TRKi was 48 days (IQR = 9-207). TRKis were commonly given as first-line (30%) or second-line (48%) therapies. Median duration of therapy was 610 (IQR = 182-764) days for TRKi use and 207.5 (IQR = 42-539) days for all other first-line therapies. CONCLUSIONS: This study reports on contemporary real-world NTRK testing patterns and use of TRKis in solid tumors, including time between NTRK testing and initiation of TRKi therapy and duration of TRKi therapy.

Background: Sevoflurane (Sev) is a widely used general anesthetic that can cause neurotoxicity. Histone acetylation is a vital epigenetic mechanism responding to environmental stresses. Objective: This study was conducted to analyze the role of histone deacetylase 3 (HDAC3) in Sev-induced neurotoxicity and provide a theoretical reference for the treatment of anesthetic neurotoxicity. Results: HDAC3 was upregulated in Sev-treated HT-22 cells. Inhibition of HDAC3 upregulated cell viability and downregulated apoptosis, oxidative stress and secretion of inflammatory cytokines. HDAC3 reduced H3K27ac and H3K9ac levels on the TrkC promoter to inhibit TrkC expression. TrkC downregulation reversed the alleviative role of si-HDAC3 in Sev-induced neurotoxicity. Conclusion: HDAC3 enhanced Sev-induced neurotoxicity by reducing H3K27ac and H3K9ac to repress TrkC. [ABSTRACT FROM AUTHOR]

TrkB and TrkC are quite common neurotrophin receptors found on the same cells in CNS. In the C-terminal tail, TrkB and TrkC differ only in two amino acid residues at positions immediately preceding the tyrosine residue, which, upon phosphorylation, becomes the docking site for phospholipase Cγ1 (PLCγ1). The question arose whether such a difference near the PLCγ1 docking site might contribute to differential response to neurotrophin. PC12 clones with the following receptors were obtained: wild-type TrkC, TrkC-Y820F with a defective PLCγ1 binding site, TrkC-T817S–I819V with two amino acid residues replaced with those in the TrkB tail. The outgrowth of neurite-like processes from TrkC-Y820F-containing cells appeared to be impaired, while the TrkC-T817S–I819V variant appeared more effective than wild-type TrkC in promoting the outgrowth of neurite-like processes after neurotrophin stimulation, at least in the compared PC12 cell clones. Taken together, both the tyrosine residue at the PLCγ1 docking site and the amino acid residues immediately preceding it appear important for TrkC-supported outgrowth of neurite-like processes.

Cancer patients undergoing treatment with antineoplastic drugs often experience chemotherapy-induced neuropathic pain (CINP), and the therapeutic options for managing CINP are limited. Here, we show that systemic paclitaxel administration upregulates the expression of neurotrophin-3 (Nt3) mRNA and NT3 protein in the neurons of dorsal root ganglia (DRG), but not in the spinal cord. Blocking NT3 upregulation attenuates paclitaxel-induced mechanical, heat, and cold nociceptive hypersensitivities and spontaneous pain without altering acute pain and locomotor activity in male and female mice. Conversely, mimicking this increase produces enhanced responses to mechanical, heat, and cold stimuli and spontaneous pain in naive male and female mice. Mechanistically, NT3 triggers tropomyosin receptor kinase C (TrkC) activation and participates in the paclitaxel-induced increases of C–C chemokine ligand 2 (Ccl2) mRNA and CCL2 protein in the DRG. Given that CCL2 is an endogenous initiator of CINP and that Nt3 mRNA co-expresses with TrkC and Ccl2 mRNAs in DRG neurons, NT3 likely contributes to CINP through TrkC-mediated activation of the Ccl2 gene in DRG neurons. NT3 may be thus a potential target for CINP treatment. Synopsis: Neurotrophin-3 (NT3) activates tropomyosin receptor kinase C (TrkC) to elevate C–C chemokine ligand 2 (CCL2) in dorsal root ganglion neurons contributing to paclitaxel-induced neuropathic pain. NT3 expression is increased in DRG neurons after systemic paclitaxel injection. Blocking this increase inhibits paclitaxel-induced nociceptive hypersensitivity. The inhibitory effect is mediated by preventing NT3-triggered TrkC activation and subsequent CCL2 production in DRG neurons. Neurotrophin-3 (NT3) activates tropomyosin receptor kinase C (TrkC) to elevate C-C chemokine ligand 2 (CCL2) in dorsal root ganglion neurons contributing to paclitaxel-induced neuropathic pain. [ABSTRACT FROM AUTHOR]

Background: Times New Roman 9, single space, contains the brief description of the research. Stroke is the greatest cause of disability and mortality worldwide. Several biological mechanisms underlying this disease such as failure of glutamate reuptake and ATP synthesis, resulting in high levels of reactive oxygen species (ROS), neuroinflammatory responses, and apoptosis, resulted in cell death and brain tissue damage. Neurotherapeutics agents are given to affect the pathophysiological pathways and prevent expanding infarct area. Objective: This study aims to analyze the modulation of Gluthatione S-Transferase (GST) and Tyrosine kinase receptor C (TrkC) by 7,8-DHF as neuroprotective agent in ischemic in silico. Methods: This study used in silico simulation to predict 7,8-dihydroxyflavone (DHF) as neuroprotective agent by using PubChem, RCSB, Biovia Discovery Studio, PyRx, and PyMol. This study analyzes the pharmacodynamics, pharmacokinetics, and molecular interactions between 7,8-DHF as a ligand with GST (13GS) and TrkC (6KZC) as protein target, compared to their native ligand. Results: 7,8-DHF may increase intracellular endogenous antioxidants mainly GST and stimulate TrkC to activate further neuron survival signaling. 7,8 DHF has a much lower bond energy (-8.1 Kcal/mol) when it binds to GST compared to the native ligand (-5.9 Kcal/mol). Besides, binding affinity between 7,8-DHF-TrkC was -9 Kcal/mol, while native ligand-TrkC was -10.6 Kcal/mol. This study showed that there were the same amino acid residues between 7,8-DHF-GST and 7,8-DHF-TrkC, compared to their native ligand. Conclusion: As an adaptive response to hypoxia caused by ischemic stroke, these findings are likely to induce protective mechanism through indirectly TrkC activation which regulates neurogenesis and increasing intracellular endogenous antioxidants.

A subset of Spitz tumors harbor fusions of NTRK3 with ETV6, MYO5A, and MYH9. We evaluated a series of 22 melanocytic tumors in which an NTRK3 fusion was identified as part of the diagnostic workup. Tumors in which NTRK3 was fused to ETV6 occurred in younger patients were predominantly composed of epithelioid melanocytes and were classified by their histopathologic features as Spitz tumors. In contrast, those in which NTRK3 was fused to MYO5A were predominantly composed of spindled melanocytes arrayed in fascicles with neuroid features such as pseudo-Verocay bodies. To further investigate the effects of the fusion kinases ETV6-NTRK3 and MYO5A-NTRK3 in melanocytes, we expressed them in immortalized melanocytes and determined their subcellular localization by immunofluorescence. ETV6-NTRK3 was localized to the nucleus and diffusely within the cytoplasm and caused melanocytes to adopt an epithelioid cytomorphology. In contrast, MYO5A-NTRK3, appeared excluded from the nucleus of melanocytes, was localized to dendrites, and resulted in a highly dendritic cytomorphology. Our findings indicate that ETV6-NTRK3 and MYO5A-NTRK3 have distinct subcellular localizations and effects on cellular morphology.

BackgroundEntrectinib is a potent inhibitor of tropomyosin receptor kinase (TRK) A, B, and C, which has been shown to have anti-tumour activity against NTRK gene fusion-positive solid tumours, including CNS activity due to its ability to penetrate the blood-brain barrier. We present an integrated efficacy and safety analysis of patients with metastatic or locally advanced solid tumours harbouring oncogenic NTRK1, NTRK2, and NTRK3 gene fusions treated in three ongoing, early-phase trials.MethodsAn integrated database comprised the pivotal datasets of three, ongoing phase 1 or 2 clinical trials (ALKA-372-001, STARTRK-1, and STARTRK-2), which enrolled patients aged 18 years or older with metastatic or locally advanced NTRK fusion-positive solid tumours who received entrectinib orally at a dose of at least 600 mg once per day in a capsule. All patients had an Eastern Cooperative Oncology Group performance status of 0-2 and could have received previous anti-cancer therapy (except previous TRK inhibitors). The primary endpoints, the proportion of patients with an objective response and median duration of response, were evaluated by blinded independent central review in the efficacy-evaluable population (ie, patients with NTRK fusion-positive solid tumours who were TRK inhibitor-naive and had received at least one dose of entrectinib). Overall safety evaluable population included patients from STARTRK-1, STARTRK-2, ALKA-372-001, and STARTRK-NG (NCT02650401; treating young adult and paediatric patients [aged ≤21 years]), who received at least one dose of entrectinib, regardless of tumour type or gene rearrangement. NTRK fusion-positive safety evaluable population comprised all patients who have received at least one dose of entrectinib regardless of dose or follow-up. These ongoing studies are registered with ClinicalTrials.gov, NCT02097810 (STARTRK-1) and NCT02568267 (STARTRK-2), and EudraCT, 2012-000148-88 (ALKA-372-001).FindingsPatients were enrolled in ALKA-372-001 from Oct 26, 2012, to March 27, 2018; in STARTRK-1 from Aug 7, 2014, to May 10, 2018; and in STARTRK-2 from Nov 19, 2015 (enrolment is ongoing). At the data cutoff date for this analysis (May 31, 2018) the efficacy-evaluable population comprised 54 adults with advanced or metastatic NTRK fusion-positive solid tumours comprising ten different tumour types and 19 different histologies. Median follow-up was 12.9 months (IQR 8·77-18·76). 31 (57%; 95% CI 43·2-70·8) of 54 patients had an objective response, of which four (7%) were complete responses and 27 (50%) partial reponses. Median duration of response was 10 months (95% CI 7·1 to not estimable). The most common grade 3 or 4 treatment-related adverse events in both safety populations were increased weight (seven [10%] of 68 patients in the NTRK fusion-positive safety population and in 18 [5%] of 355 patients in the overall safety-evaluable population) and anaemia (8 [12%] and 16 [5%]). The most common serious treatment-related adverse events were nervous system disorders (three [4%] of 68 patients and ten [3%] of 355 patients). No treatment-related deaths occurred.InterpretationEntrectinib induced durable and clinically meaningful responses in patients with NTRK fusion-positive solid tumours, and was well tolerated with a manageable safety profile. These results show that entrectinib is a safe and active treatment option for patients with NTRK fusion-positive solid tumours. These data highlight the need to routinely test for NTRK fusions to broaden the therapeutic options available for patients with NTRK fusion-positive solid tumours.FundingIgnyta/F Hoffmann-La Roche.

BackgroundAn early-life anxious temperament (AT) is a risk factor for the development of anxiety, depression, and comorbid substance abuse. We validated a nonhuman primate model of early-life AT and identified the dorsal amygdala as a core component of AT's neural circuit. Here, we combine RNA sequencing, viral-vector gene manipulation, functional brain imaging, and behavioral phenotyping to uncover AT's molecular substrates.MethodsIn response to potential threat, AT and brain metabolism were assessed in 46 young rhesus monkeys. We identified AT-related transcripts using RNA-sequencing data from dorsal amygdala tissue (including central nucleus of the amygdala [Ce] and dorsal regions of the basal nucleus). Based on the results, we overexpressed the neurotrophin-3 gene, NTF3, in the dorsal amygdala using intraoperative magnetic resonance imaging-guided surgery (n = 5 per group).ResultsThis discovery-based approach identified AT-related alterations in the expression of well-established and novel genes, including an inverse association between NTRK3 expression and AT. NTRK3 is an interesting target because it is a relatively unexplored neurotrophic factor that modulates intracellular neuroplasticity pathways. Overexpression of the transcript for NTRK3's endogenous ligand, NTF3, in the dorsal amygdala resulted in reduced AT and altered function in AT's neural circuit.ConclusionsTogether, these data implicate neurotrophin-3/NTRK3 signaling in the dorsal amygdala in mediating primate anxiety. More generally, this approach provides an important step toward understanding the molecular underpinnings of early-life AT and will be useful in guiding the development of treatments to prevent the development of stress-related psychopathology.

During prenatal life, exposure to synthetic glucocorticoids (SGCs) can alter normal foetal development, resulting in disease later in life. Previously, we have shown alterations in the dendritic cytoarchitecture of Purkinje cells in adolescent rat progeny prenatally exposed to glucocorticoids. However, the molecular mechanisms underlying these alterations remain unclear. A possible molecular candidate whose deregulation may underlie these changes is the glucocorticoid receptor (GR) and neurotrophin 3/ tropomyosin receptor kinase C, neurotrophic complex (NT-3/TrkC), which specifically modulates the development of the neuronal connections in the cerebellar vermis. To date, no evidence has shown that the cerebellar expression levels of this neurotrophic complex are affected by exposure to a synthetic glucocorticoid in utero. Therefore, the first objective of this investigation was to evaluate the expression of GR, NT-3 and TrkC in the cerebellar vermis using immunohistochemistry and western blot techniques by evaluating the progeny during the postnatal stage equivalent to adolescence (postnatal Day 52). Additionally, we evaluated anxiety-like behaviours in progeny using the elevated plus maze and the marble burying test. In addition, an environmental enrichment (EE) can increase the expression of some neurotrophins and has anxiolytic power. Therefore, we wanted to assess whether an EE reversed the long-term alterations induced by prenatal betamethasone exposure. The major findings of this study were as follows: i) prenatal betamethasone (BET) administration decreases GR, NT-3 and TrkC expression in the cerebellar vermis ii) prenatal BET administration decreases GR expression in the cerebellar hemispheres and iii) enhances the anxiety-like behaviours in the same progeny, and iv) exposure to an EE reverses the reduced expression of GR, NT-3 and TrkC in the cerebellar vermis and v) decreases anxiety-like behaviours. In conclusion, an enriched environment applied 18 days post-weaning was able to restabilize GR, NT-3 and TrkC expression levels and reverse anxious behaviours observed in adolescent rats prenatally exposed to betamethasone.

Conventional cancer therapies such as chemotherapy are non-selective and induce immune system anergy, which lead to serious side effects and tumor relapse. It is a challenge to prime the body's immune system in the cancer-bearing subject to produce cancer antigen-targeting antibodies, as most tumor-associated antigens are expressed abundantly in cancer cells and some of normal cells. This study illustrates how hapten-based pre-immunization (for anti-hapten antibodies production) combined with cancer receptor labeling with hapten antigen constructs can elicit antibody-dependent cellular phagocytosis (ADCP). Thus, the hapten antigen 2,4-dinitrophenol (DNP) was covalently combined with a cancer receptor-binding dipeptide (IYIY) to form a dipeptide-hapten construct (IYIY-DNP, MW = 1322.33) that targets the tropomyosin receptor kinase C (TrkC)-expressed on the surface of metastatic cancer cells. IYIY-DNP facilitated selective association of RAW264.7 macrophages to the TrkC expressing 4T1 cancer cells in vitro, forming cell aggregates in the presence of anti-DNP antibodies, suggesting initiation of anti-DNP antibody-dependent cancer cell recognition of macrophages by the IYIY-DNP. In in vivo, IYIY-DNP at 10 mg/kg suppressed growth of 4T1 tumors in DNP-immunized BALB/c mice by 45% (p < 0.05), when comparing the area under the tumor growth curve to that of the saline-treated DNP-immunized mice. Meanwhile, IYIY-DNP at 10 mg/kg had no effect on TrkC-negative 67NR tumor-bearing mice immunized with DNP. Tumor growth suppression activity of IYIY-DNP in DNP-immunized mice was associated with an increase in the anti-DNP IgG (7.3 × 106 ± 1.6 U/mL) and IgM (0.9 × 106 ± 0.07 U/mL) antibodies after five cycles of DNP treatment, demonstrated potential for hapten-based pre-immunization then treatment with IYIY-DNP to elicit ADCP for improved immunotherapy of TrkC expressing cancers. [ABSTRACT FROM AUTHOR]

During prenatal life, exposure to synthetic glucocorticoids (SGCs) can alter normal foetal development, resulting in disease later in life. Previously, we have shown alterations in the dendritic cytoarchitecture of Purkinje cells in adolescent rat progeny prenatally exposed to glucocorticoids. However, the molecular mechanisms underlying these alterations remain unclear. A possible molecular candidate whose deregulation may underlie these changes is the glucocorticoid receptor (GR) and neurotrophin 3/ tropomyosin receptor kinase C, neurotrophic complex (NT-3/TrkC), which specifically modulates the development of the neuronal connections in the cerebellar vermis. To date, no evidence has shown that the cerebellar expression levels of this neurotrophic complex are affected by exposure to a synthetic glucocorticoid in utero. Therefore, the first objective of this investigation was to evaluate the expression of GR, NT-3 and TrkC in the cerebellar vermis using immunohistochemistry and western blot techniques by evaluating the progeny during the postnatal stage equivalent to adolescence (postnatal Day 52). Additionally, we evaluated anxiety-like behaviours in progeny using the elevated plus maze and the marble burying test. In addition, an environmental enrichment (EE) can increase the expression of some neurotrophins and has anxiolytic power. Therefore, we wanted to assess whether an EE reversed the long-term alterations induced by prenatal betamethasone exposure. The major findings of this study were as follows: i) prenatal betamethasone (BET) administration decreases GR, NT-3 and TrkC expression in the cerebellar vermis ii) prenatal BET administration decreases GR expression in the cerebellar hemispheres and iii) enhances the anxiety-like behaviours in the same progeny, and iv) exposure to an EE reverses the reduced expression of GR, NT-3 and TrkC in the cerebellar vermis and v) decreases anxiety-like behaviours. In conclusion, an enriched environment applied 18 days post-weaning was able to restabilize GR, NT-3 and TrkC expression levels and reverse anxious behaviours observed in adolescent rats prenatally exposed to betamethasone. [ABSTRACT FROM AUTHOR]

BackgroundAbout 10-15% of adult, and most pediatric, gastrointestinal stromal tumors (GIST) lack mutations in KIT, PDGFRA, SDHx, or RAS pathway components (KRAS, BRAF, NF1). The identification of additional mutated genes in this rare subset of tumors can have important clinical benefit to identify altered biological pathways and select targeted therapies.MethodsWe performed comprehensive genomic profiling (CGP) for coding regions in more than 300 cancer-related genes of 186 GISTs to assess for their somatic alterations.ResultsWe identified 24 GIST lacking alterations in the canonical KIT/PDGFRA/RAS pathways, including 12 without SDHx alterations. These 24 patients were mostly adults (96%). The tumors had a 46% rate of nodal metastases. These 24 GIST were more commonly mutated at 7 genes: ARID1B, ATR, FGFR1, LTK, SUFU, PARK2 and ZNF217. Two tumors harbored FGFR1 gene fusions (FGFR1-HOOK3, FGFR1-TACC1) and one harbored an ETV6-NTRK3 fusion that responded to TRK inhibition. In an independent sample set, we identified 5 GIST cases lacking alterations in the KIT/PDGFRA/SDHx/RAS pathways, including two additional cases with FGFR1-TACC1 and ETV6-NTRK3 fusions.ConclusionsUsing patient demographics, tumor characteristics, and CGP, we show that GIST lacking alterations in canonical genes occur in younger patients, frequently metastasize to lymph nodes, and most contain deleterious genomic alterations, including gene fusions involving FGFR1 and NTRK3. If confirmed in larger series, routine testing for these translocations may be indicated for this subset of GIST. Moreover, these findings can be used to guide personalized treatments for patients with GIST. Trial registration NCT 02576431. Registered October 12, 2015.

Peripheral nerve regeneration relies on the ability of Schwann cells to support the regrowth of damaged axons. Schwann cells re-differentiate when reestablishing contact with the sprouting axons, with large fibers becoming remyelinated and small nociceptive fibers ensheathed and collected into Remak bundles. We have previously described how the receptor sortilin facilitates neurotrophin signaling in peripheral neurons via regulated trafficking of Trk receptors. This study aims to characterize the effects of sortilin deletion on nerve regeneration following sciatic crush injury. We found that Sort1 –/– mice displayed functional motor recovery like that of WT mice, with no detectable differences in relation to nerve conduction velocities and morphological aspects of myelinated fibers. In contrast, we found abnormal ensheathment of regenerated C-fibers in injured Sort1 –/– mice, demonstrating a role of sortilin for Remak bundle formation following injury. Further studies on Schwann cell signaling pathways showed a significant reduction of MAPK/ERK, RSK, and CREB phosphorylation in Sort1 –/– Schwann cells after stimulation with neurotrophin-3 (NT-3), while Schwann cell migration and myelination remained unaffected. In conclusion, our results demonstrate that loss of sortilin blunts NT-3 signaling in Schwann cells which might contribute to the impaired Remak bundle regeneration after sciatic nerve injury. [ABSTRACT FROM AUTHOR]

Peripheral nerve regeneration relies on the ability of Schwann cells to support the regrowth of damaged axons. Schwann cells re-differentiate when reestablishing contact with the sprouting axons, with large fibers becoming remyelinated and small nociceptive fibers ensheathed and collected into Remak bundles. We have previously described how the receptor sortilin facilitates neurotrophin signaling in peripheral neurons via regulated trafficking of Trk receptors. This study aims to characterize the effects of sortilin deletion on nerve regeneration following sciatic crush injury. We found that Sort1–/– mice displayed functional motor recovery like that of WT mice, with no detectable differences in relation to nerve conduction velocities and morphological aspects of myelinated fibers. In contrast, we found abnormal ensheathment of regenerated C-fibers in injured Sort1–/– mice, demonstrating a role of sortilin for Remak bundle formation following injury. Further studies on Schwann cell signaling pathways showed a significant reduction of MAPK/ERK, RSK, and CREB phosphorylation in Sort1–/– Schwann cells after stimulation with neurotrophin-3 (NT-3), while Schwann cell migration and myelination remained unaffected. In conclusion, our results demonstrate that loss of sortilin blunts NT-3 signaling in Schwann cells which might contribute to the impaired Remak bundle regeneration after sciatic nerve injury.

BackgroundThere are limited data on the histopathology of papillary thyroid carcinomas (PTCs) diagnosed in irradiated populations. We evaluated the associations between iodine-131 dose and the histopathological characteristics of post-Chernobyl PTCs, the changes in these characteristics over time, and their associations with selected somatic mutations.MethodsThis study included 115 PTCs diagnosed in a Ukrainian-American cohort (n=13,243) during prescreening and four successive thyroid screenings. Of these PTCs, 65 were subjected to somatic mutation profiling. All individuals were

Neurotrophin receptors regulate neuronal survival and network formation, as well as synaptic plasticity in the brain via interaction with their ligands. Here, we examined early changes in the expression of neurotrophin receptor genes Ntk1 (TrkA), Ntrk2 (TrkB), Ntrk3 (TrkC), Ngfr (p75NTR) and miRNAs that target theses gens in the mouse brain after induction of seizure activity by pentylenetetrazol. We found that expression of Ntrk3 and Ngfr was upregulated in the cortex and the hippocampus 1-3 hours after the seizures, while Ntrk2 expression increased after 3-6 hours in the anterior cortex and after 1 and 6 hours in the hippocampus. At the same time, the ratio of Bcl-2/Bax signaling proteins increased in the anterior and posterior cortex, but not in the hippocampus, suggesting the activation of anti-apoptotic signaling. Expression of miRNA-9 and miRNA-29a, which were predicted to target Ntrk3, was upregulated in the hippocampus 3 hours after pentylenetetrazol injection. Therefore, early cellular response to seizures in the brain includes induction of the Ntrk2, Ntrk3, Ngfr, miRNA-9, and miRNA-29a expression, as well as activation of Bcl-2 and Bax signaling pathways, which may characterize them as important mediators of neuronal adaptation and survival upon induction of the generalized brain activity. [ABSTRACT FROM AUTHOR]

BackgroundSchizophrenia is a complex neuropsychiatric disorder of unclear etiology. The strongest known genetic risk factor is the 22q11.2 microdeletion. Research has yet to confirm which genes within the deletion region are implicated in schizophrenia. The minimal 1.5 megabase deletion contains MIR185, which encodes microRNA 185.MethodsWe determined miR-185 expression in embryonic and adult mouse brains. Common and rare variants at this locus were then investigated using a human genetics approach. First, we performed gene-based analyses for MIR185 common variants and target genes using Psychiatric Genomics Consortium genome-wide association data. Second, MIR185 was resequenced in German patients (n = 1000) and controls (n = 500). We followed up promising variants by genotyping an additional European sample (patients, n = 3598; controls, n = 4082).ResultsIn situ hybridization in mice revealed miR-185 expression in brain regions implicated in schizophrenia. Gene-based tests revealed association between common variants in 3 MIR185 target genes (ATAT1, SH3PXD2A, NTRK3) and schizophrenia. Further analyses in mice revealed overlapping expression patterns for these target genes and miR-185. Resequencing identified 2 rare patient-specific novel variants flanking MIR185. However, follow-up genotyping provided no further evidence of their involvement in schizophrenia.LimitationsPower to detect rare variant associations was limited.ConclusionHuman genetic analyses generated no evidence of the involvement of MIR185 in schizophrenia. However, the expression patterns of miR-185 and its target genes in mice, and the genetic association results for the 3 target genes, suggest that further research into the involvement of miR-185 and its downstream pathways in schizophrenia is warranted.

Neurotrophin‐3 (NT‐3) acts as an important growth factor to stimulate and control tissue development. The NT‐3 receptor, TRKC, is expressed in rat testis. Its function in regulation of stem Leydig cell development and its underlying mechanism remain unknown. Here, we reported the role of NT‐3 to regulate stem Leydig cell development in vivo and in vitro. Ethane dimethane sulphonate was used to kill all Leydig cells in adult testis, and NT‐3 (10 and 100 ng/testis) was injected intratesticularly from the 14th day after ethane dimethane sulphonate injection for 14 days. NT‐3 significantly reduced serum testosterone levels at doses of 10 and 100 ng/testis without affecting serum luteinizing hormone and follicle‐stimulating hormone levels. NT‐3 increased CYP11A1‐positive Leydig cell number at 100 ng/testis and lowered Leydig cell size and cytoplasmic size at doses of 10 and 100 ng/testis. After adjustment by the Leydig cell number, NT‐3 significantly down‐regulated the expression of Leydig cell genes (Lhcgr, Scarb1, Star, Cyp11a1, Hsd3b1, Cyp17a1, Hsd17b3, Hsd11b1, Insl3, Trkc and Nr5a1) and the proteins. NT‐3 increased the phosphorylation of AKT1 and mTOR, decreased the phosphorylation of 4EBP, thereby increasing ATP5O. In vitro study showed that NT‐3 dose‐dependently stimulated EdU incorporation into stem Leydig cells and inhibited stem Leydig cell differentiation into Leydig cells, thus leading to lower medium testosterone levels and lower expression of Lhcgr, Scarb1, Trkc and Nr5a1 and their protein levels. NT‐3 antagonist Celitinib can antagonize NT‐3 action in vitro. In conclusion, the present study demonstrates that NT‐3 stimulates stem Leydig cell proliferation but blocks the differentiation via TRKC receptor. [ABSTRACT FROM AUTHOR]

Background and objectives: Cerebral ischemia causes irreversible structural and functional damage in certain areas of the brain, especially the hippocampus. Evidence indicates that physical exercise may reduce the damages caused by cerebral ischemia. The purpose of this study was to examine effects of eight weeks of exercise preconditioning on the expression of neurotrophin-3 (NT-3) and tyrosine kinase receptor C (TrkC) in the CA1 region of the hippocampus after cerebral ischemicreperfusion in male rats. Methods: Twenty one male Wistar rats weighing 250-300 g were randomly selected and divided into three groups (healthy control, control+ischemia and exercise+ischemia). Rats in the exercise group ran on a treadmill, five days per week for eight weeks. Ischemia was induced by occlusion of both common carotid arteries for 45 minutes. In order to evaluate gene expression, real-time PCR was performed. Results: The expression of NT-3 gene was significantly higher in the exercise+ischemia and control+ischemia groups than in the healthy control group (P<0.05). Moreover, TrkC gene expression was significantly lower in the exercise+ischemia and control+ischemia groups than in the healthy control group (P<0.05). Conclusion: Exercise before the induction of ischemic stroke increases NT-3 expression but does not influence TrkC expression. [ABSTRACT FROM AUTHOR]

Abstract Tissue engineering produces constructs with defined functions for the targeted treatment of damaged tissue. A complete spinal cord injury (SCI) model is generated in canines to test whether in vitro constructed neural network (NN) tissues can relay the excitatory signal across the lesion gap to the caudal spinal cord. Established protocols are used to construct neural stem cell (NSC)‐derived NN tissue characterized by a predominantly neuronal population with robust trans‐synaptic activities and myelination. The NN tissue is implanted into the gap immediately following complete transection SCI of canines at the T10 spinal cord segment. The data show significant motor recovery of paralyzed pelvic limbs, as evaluated by Olby scoring and cortical motor evoked potential (CMEP) detection. The NN tissue survives in the lesion area with neuronal phenotype maintenance, improves descending and ascending nerve fiber regeneration, and synaptic integration with host neural circuits that allow it to serve as a neuronal relay to transmit excitatory electrical signal across the injured area to the caudal spinal cord. These results suggest that tissue‐engineered NN grafts can relay the excitatory signal in the completely transected canine spinal cord, providing a promising strategy for SCI treatment in large animals, including humans.

Objective: Nowadays, there seems to be no decisive way for treatment of spinal cord injury (SCI).Extensive cell death (apoptosis and necrosis) occurring in SCI can cause considerable progressive sensorimotor disabilities. Preventing cell death by improving endogenous regenerative capability could an effective strategy for the treatment of SCI. This study was designed to evaluate the effects of lithium chloride (LiCl) on the cell survival through overexpression of BDNF and NT3 mRNA level and their receptors in the contusion rat models. Methods: Rats were randomly divided into four experimental groups (eight rats/group) including: contused animals (the non-treatment group); contused animals (the control group) which received laminectomy; contused animals received normal saline (vehicle)and contused animals received intraperitoneal injection of 20 mg/kg LiCl three days after surgery. Injection continued for 14 days as treatment. Basso, Beattie, Bresnahan (BBB) rating scale was used to assess the motor function of the rats. To evaluate the histopathological and gene expression analysis, rats were sacrificed 28 days after surgery. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) was performed to obtain the relative levels of mRNA for BDNF, NT3 and their receptors. Results: The results showed LiCl ameliorates BBB scores via up-regulation of BDNF and TrkB receptors. Also, histological analysis showed that the numerical density per area of TUNEL- positive cells and the percentage of cavity significantly decreased in the LiCl-treated group. Conclusion: Our findings suggest that LiCl protects neural cells and effectively enhances locomotor function, which was done through up-regulation of endogenous BDNF expression in rats with SCI. Abbreviations: SCI: spinal cord injury; LiCl: lithium chloride; BDNF: Brain-derived neurotrophic factor; NT3: Neurotrophin-3; BBB: Basso, Beattie, Bresnahan; TrkB: Tropomyosin receptor kinase B; TUNEL: Terminal deoxynucleotidyl transferase dUTP nick end labeling. [ABSTRACT FROM AUTHOR]

ВВЕДЕНИЕ: Модель шизофрении, связанной с нарушениями в развитии постулирует патологические отклонения в эмбриональном нейрогенезе в качестве этиопатогенетической основы шизофренических психозов. Гипотеза о нейротрофических факторах объясняет данные нейропатологические отклонения как результат нарушений в системе нейротрофинов, вызванных различными генетическими, инфекциозными и травматическими факторами. Тирозинкиназные рецепторы trkB и trkC опосредуют эффекты нейротрофинов, стимулирующих рост и соответствуют изменениям в их наличности. ЦЕЛЬ: Целью настоящего исследования является установление модели экспрессии trkB и trkC в мозговых структурах крысы при экспериментальной модели шизофрении. МАТЕРИАЛЫ И МЕТОДЫ: На криостатных срезах мозга контрольных и испытуемых крыс (после билатеральной инфузии изибутановой кислоты в гиппокампальную формацию) была прослежена иммунореактивность на trkB и trkC. РЕЗУЛЬТАТЫ: Наш анализ выявил заниженную экспрессию рецепторов trkB и trkC в гиппокампальной формации испытуемых животных по сравнению с контрольными. Количественное измерение интенсивности иммуногистохимических реакций и статистический анализ подтвердили понижение иммунореактивности исследуемых антигенов (trkB и trkC) в позитивных гиппокампальных нейронах у испытуемых крыс 56-дневного возраста по сравнению с иммунореактивностью контрольных животных. ЗАКЛЮЧЕНИЕ: Установленное понижение в экспрессии рецепторов нейротрофических факторов можно рассматривать в связи с нарушением функции и пластичности гиппокампальной формации в мозге при шизофрении.

Abstract Perineural invasion (PNI) potentially increases the risk of relapse and abdominal pain in patients with pancreatic ductal adenocarcinoma (PDAC). However, the underlying mechanisms of PNI of PDAC is incompletely revealed. Our study aimed to investigate roles of miR-429 in modulating PNI in PDAC. We found that miR-429 was downregulated in PDAC cancer tissues and was profoundly decreased in tissues with PNI. It was reduced in nine of the ten examined pancreatic cancer cell lines. MiR-429 mimics restored its cellular expressions in MIA PaCa-2 and BxCP3 cells and significantly suppressed cell viability and invasion of the cancer cells. The online bioinformatic software predicted that neurotrophin-3 (NT-3) was a potential target gene of miR-429. It was showed that NT-3 mRNA elevated in PC cancer tissues, especially in patients presenting PNI. MiR-429 upregulation substantially suppressed the NT-3 mRNA and secretion in cancer cells. Also, the dual luciferase reporter assays confirmed the interaction between miR-429 and NT-3. When co-culturing the two PDAC cells with PC-12 cells, the invaded cell counts significantly increased comparing with the sole culture of cancer cells. However, miR-429 mimic transfection or NT-3 blocking retarded the cancer invasion in the co-culture system. Besides, we found that cancer cells conditioned medium (CM) treatment significantly increased the neurite outgrowth percentage in PC-12 cells, which was suppressed by culturing with CM from miR-429 mimics-transfected cells. In the CM cultured PC-12 cells, NT-3 receptor TrkC as well as pain-related proteins TRPV1 and TRPV2 significantly elevated. Collectively, miR-429 potentially suppressed neurotrophin-3 to alleviate PNI of PDAC. Highlights • MiR-429 is downregulated in pancreatic cancer tissues and cells. • MiR-429 functions to inhibit cancer cell proliferation and invasion. • MiR-429 directly targets to NT-3 mRNA. • MiR-429 suppress NT-3 in cancer cells to resist the attraction TrkC in PC12 cells. • NT-3-TrkC signaling promotes PC12 neurite outgrowth and neuropathic pain. [ABSTRACT FROM AUTHOR]

We have reported previously that bone marrow mesenchymal stem cell (MSC)-derived neural network scaffold not only survived in the injury/graft site of spinal cord but also served as a “neuronal relay” that was capable of improving the limb motor function in a complete spinal cord injury (SCI) rat model. It remained to be explored whether such a strategy was effective for repairing the large spinal cord tissue loss as well as restoring motor function in larger animals. We have therefore extended in this study to construct a canine MSC-derived neural network tissue in vitro with the aim to evaluate its efficacy in treating adult beagle dog subjected to a complete transection of the spinal cord. The results showed that after co-culturing with neurotropin-3 overexpressing Schwann cells in a gelatin sponge scaffold for 14 days, TrkC overexpressing MSCs differentiated into neuron-like cells. In the latter, some cells appeared to make contacts with each other through synapse-like structures with trans-synaptic electrical activities. Remarkably, the SCI canines receiving the transplantation of the MSC-derived neural network tissue demonstrated a gradual restoration of paralyzed limb motor function, along with improved electrophysiological presentation when compared with the control group. Magnetic resonance imaging and diffusion tensor imaging showed that the canines receiving the MSC-derived neural network tissue exhibited robust nerve tract regeneration in the injury/graft site. Histological analysis showed that some of the MSC-derived neuron-like cells had survived in the injury/graft site up to 6.5 months. Implantation of MSC-derived neural network tissue significantly improved the microenvironment of the injury/graft site. It is noteworthy that a variable number of them had integrated with the regenerating corticospinal tract nerve fibers and 5-HT nerve fibers through formation of synapse-like contacts. The results suggest that the transplanted MSC-derived neural network tissue may serve as a structural and functional “neuronal relay” to restore the paralyzed limb motor function in the canine with complete SCI. [ABSTRACT FROM AUTHOR]

Summary: Aims: Neurotrophin‐3 (NT‐3) is expressed in the mouse striatum; however, it is not clear the NT‐3 role in striatal physiology. The expression levels of mRNAs and immune localization of the NT‐3 protein and its receptor TrkC are altered in the striatum following damage induced by an in vivo treatment with 3‐nitropropionic acid (3‐NP), a mitochondrial toxin used to mimic the histopathological hallmarks of Huntington's disease (HD). The aim of this study was to evaluate the role of NT‐3 on corticostriatal synaptic transmission and its plasticity in both the control and damaged striatum. Methods: Corticostriatal population spikes were electrophysiologically recorded and striatal synaptic plasticity was induced by high‐frequency stimulation. Further, the phosphorylation status of Trk receptors was tested under conditions that imitated electrophysiological experiments. Results: NT‐3 modulates both synaptic transmission and plasticity in the striatum; nonetheless, synaptic plasticity was modified by the 3‐NP treatment, where instead of producing striatal long‐term depression (LTD), long‐term potentiation (LTP) was obtained. Moreover, the administration of NT‐3 in the recording bath restored the plasticity observed under control conditions (LTD) in this model of striatal degeneration. Conclusion: NT‐3 modulates corticostriatal transmission through TrkB stimulation and restores striatal LTD by signaling through its TrkC receptor. [ABSTRACT FROM AUTHOR]

Introduction: Medulloblastoma is a malignant embryonal tumor of the cerebellum with poor prognosis. The treatment is based only on clinical criteria, such as risk group that only considers age, extent of tumor resection, recurrence, and metastasis. Objective: To evaluate a possible relationship between the immunoexpression of biomarkers (Ki67, receptor neutrophin-3 [TRKC], epidermal growth factor receptor [EGFR], B-cell lymphoma 2 [Bcl-2], and cyclin-D1), and the classical clinical prognostic factors of medulloblastoma. Material and method: thirty-five samples of pediatric medulloblastoma free of neoadjuvant chemotherapy were separated and reviewed for their histopathological classification; two areas representative of tumor were used in the construction of tissue microarrays. The following clinical data from 29 patients were used for comparison with the biomarkers expression: patient's age, presence or absence of complete tumor resection, staging patient's risk group, presence or absence of metastases, presence or absence of postoperative chemotherapy, and presence or absence of recurrence. Clinical follow-up of the study ranged from two to thirteen years, and cases with fatal outcome were also analyzed. Results: Patients with upper age showed higher expression of TRKC (p = 0.033). There was inversely proportional and statistically significant correlation between TRKC and Ki67 (p = 0.027). There was no statistical significance in the analysis of EGFR, Bcl2, and cyclin-D1. Conclusion: The immunoexpression of TRKC might be considered a biomarker related to tumors with better prognosis in patients with medulloblastoma, contributing to better risk groups' stratification.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and often has a poor prognosis. The present study investigated the role of the low affinity nerve growth factor receptor CD271 as a putative therapy target in HNSCC. Neurotrophins that bind to CD271 also have a high affinity for the tropomyosin receptor kinase family (Trk), consisting of TrkA, TrkB, and TrkC, which must also be considered in addition to CD271. A retrospective study and functional in vitro cell line tests (migration assay and cell sorting) were conducted in order to evaluate the relevance of CD271 expression alone and with regard to Trk expression. CD271 and Trks were heterogeneously expressed in human HNSCC. The vast majority of tumors exhibited CD271 and TrkA, whereas only half of the tumors expressed TrkB and TrkC. High expression of CD271-positive cells predicted a bad clinical outcome of patients with HNSCC and was associated with distant metastases. However, the human carcinomas that also expressed TrkC had a reduced correlation with distant metastases and better survival rates. In vitro, CD271 expression marked a subpopulation with higher proliferation rates, but proliferation was lower in tumor cells that co-expressed CD271 and TrkC. The CD271 inhibitor LM11A 31 suppressed cell motility in vitro. However, neither TrkA nor TrkB expression were linked to prognosis or cell proliferation. We conclude that CD271 is a promising candidate that provides prognostic information for HNSCC and could be a putative target for HNSCC treatment.

Bone marrow stromal cells (BMSCs) are attractive cellular sources for cell therapy of many diseases, specifically neurodegenerative ones. The potential capability of BMSCs could be further augmented by enhancing their neuroprotective property, differentiation potential, and survival rate subsequent to transplantation. Therefore, a concurrent upregulation of neurotrophin-3 ( NT- 3) and its high affinity receptor, tyrosin kinase C (TrkC), was utilized in our study. BMSCs were cotransfected with pDsRed1-N1-NT-3 and pCMX-TrkC plasmids before induction of neural differentiation. pEGFP-N1-transfected BMSCs were also employed as a control. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was employed for gene expression analysis. Cell viability was evaluated by MTT assay, while apoptosis rate was assessed by flow cytometry after PI and Annexin V staining. NT-3 and TrkC mRNA levels were greatly elevated following cotransfection of cells with pDsRed1-N1-NT-3 and pCMX-TrkC vectors. The expression of neural markers (i.e., NFM, and NeuroD1) was augmented in cotransfected BMSCs, compared to the control ones, after neural induction. At each time point, the viability and apoptosis rates of the cells over-expressing NT- 3 and TrkC showed increased and reduced patterns, respectively. Our data demonstrated that NT- 3/ TrkC-co-transfected BMSCs, compared to those of intact cells, could be more beneficial graft candidates for the upcoming treatment strategies of neurogenic disorders due to their increased viability and expression of neural markers. This may be due to their increased level of neural differentiation potential and/or their enhanced rate of survival and/or their useful capacity to secrete NT-3. [ABSTRACT FROM AUTHOR]

Although clinically useful for the treatment of various diseases, type I interferons (IFNs) have been implicated as causative factors of a number of neuroinflammatory disorders characterized by neuronal damage and altered CNS functions. As neurotrophin 3 (NT3) plays a critical role in neuroprotection, we examined the effects of IFN-β on the signalling and functional activity of the NT3/TrkC system. We found that prolonged exposure of differentiated human SH-SY5Y neuroblastoma cells to IFN-β impaired the ability of NT3 to induce transphosphorylation of the full-length TrkC receptor (TrkC-FL) and the phosphorylation of downstream signalling molecules, including PLCγ1, Akt, GSK-3β and ERK1/2. NT3 was effective in protecting the cells against apoptosis triggered by serum withdrawal or thapsigargin but not IFN-β. Prolonged exposure to the cytokine had little effects on TrkC-FL levels but markedly enhanced the messenger RNA (mRNA) and protein levels of the truncated isoform TrkC-T1, a dominant-negative receptor that inhibits TrkC-FL activity. Cell depletion of TrkC-T1 by small interfering RNA (siRNA) treatment enhanced NT3 signalling through TrkC-FL and allowed the neurotrophin to counteract IFN-β-induced apoptosis. Furthermore, the upregulation of TrkC-T1 by IFN-β was associated with the inhibition of NT3-induced recruitment of the scaffold protein tamalin to TrkC-T1 and tamalin tyrosine phosphorylation. These data indicate that IFN-β exerts a negative control on NT3 pro-survival signalling through a novel mechanism involving the upregulation of TrkC-T1. [ABSTRACT FROM AUTHOR]

Tropomyosin-receptor-kinase (Trk) receptors have been extensively studied for their roles in kinase-dependent signaling cascades in nervous system development. Synapse organization is coordinated by trans-synaptic interactions of various cell adhesion proteins, a representative example of which is the neurexin–neuroligin complex. Recently, a novel role for TrkC as a synapse organizing protein has been established. Post-synaptic TrkC binds to pre-synaptic type-IIa receptor-type protein tyrosine phosphatase sigma (PTPσ). TrkC–PTPσ specifically induces excitatory synapses in a kinase domain-independent manner. TrkC has distinct extracellular domains for PTPσ- and NT-3-binding and thus may bind both ligands simultaneously. Indeed, NT-3 enhances the TrkC–PTPσ interaction, thus facilitating synapse induction at the pre-synaptic side and increasing pre-synaptic vesicle recycling in a kinase-independent fashion. A crystal structure study has revealed the detailed structure of the TrkC–PTPσ complex as well as competitive modulation of TrkC-mediated synaptogenesis by heparan sulfate proteoglycans (HSPGs), which bind the same domain of TrkC as PTPσ. Thus, there is strong evidence supporting a role for the TrkC–PTPσ complex in mechanisms underlying the fine turning of neural connectivity. Furthermore, disruption of the TrkC–PTPσ complex may be the underlying cause of certain psychiatric disorders caused by mutations in the gene encoding TrkC ( NTRK3 ), supporting its role in cognitive functions. [ABSTRACT FROM AUTHOR]

Accumulating evidence has suggested that neurotrophins participate in the pathophysiology of mood disorders. We have developed transgenic mice overexpressing the full-length neurotrophin-3 receptor TrkC (TgNTRK3) in the central nervous system. TgNTRK3 mice show increased anxiety-like behavior and enhancement of panic reaction in the mouse defense test battery, along with an increase in the number and density of catecholaminergic (tyrosine hydroxylase positive) neurons in locus coeruleus and substantia nigra. Furthermore, treatment of TgNTRK3 mice with diazepam significantly attenuated the anxiety-like behaviors in the plus maze. These results provide evidence for the involvement of TrkC in the development of noradrenergic neurons in the central nervous system with consequences on anxiety-like behavior and panic reaction. Thus, changes in TrkC expression levels could contribute to the phenotypic expression of panic disorder through a trophic effect on noradrenergic neurons in the locus coeruleus. Our results demonstrate that the elevated NT3-TrkC tone via overexpression of TrkC in the brain may constitute a molecular mechanism for the expression of anxiety and anxiety.

PI3K/AKT signaling is involved in cell survival, proliferation, and migration. In this pathway, PI3Kα enzyme is composed of a regulatory protein encoded by p85 gene and a catalytic protein encoded by PIK3CA gene. Human PIK3CA locus is amplified in several cancers including lung and colorectal cancer (CRC). Therefore, microRNAs (miRNAs) that are encoded within the PIK3CA gene might have a role in cancer development. Here, we report a novel microRNA named PIK3CA-miR1 (EBI accession no. LN626315), which is located within PIK3CA gene. A DNA segment corresponding to PIK3CA-premir1 sequence was transfected in human cell lines that resulted in generation of mature exogenous PIK3CA-miR1. Following the overexpression of PIK3CA-miR1, its predicted target genes ( APPL1 and TrkC) were significantly downregulated in the CRC-originated HCT116 and SW480 cell lines, detected by qRT-PCR. Then, dual luciferase assay supported the interaction of PIK3CA-miR1 with APPL1 and TrkC transcripts. Endogenous PIK3CA-miR1 expression was also detected in several cell lines (highly in HCT116 and SW480) and highly in CRC specimens. Consistently, overexpression of PIK3CA-premir1 in HCT116 and SW480 cells resulted in significant reduction of the sub-G1 cell distribution and apoptotic cell rate, as detected by flowcytometry, and resulted in increased cell proliferation, as detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PIK3CA-miR1 overexpression also resulted in Wnt signaling upregulation detected by Top/Fop assay. Overall, accumulative evidences indicated the presence of a bona fide novel onco-miRNA encoded within the PIK3CA oncogene, which is highly expressed in colorectal cancer and has a survival effect in CRC-originated cells. [ABSTRACT FROM AUTHOR]

Neurotrophins stimulate the regeneration of neural tissue after lesions. It is also known that the sources of neurogenesis and cerebral function recovery are predominantly located in subcortical brain structures. The effects of ischemia on the expression of genes that encode neurotrophins ( Bdnf, Ngf, Nt-3) and their receptors ( TrkB, TrkA, TrkC, p75) in brain structures outside the lesion site were studied 3, 24, and 72 h after irreversible unilateral occlusion of the middle cerebral artery in rats. Changes in the mRNA expression of these genes were assessed by relative quantification using real-time RT-PCR. Sham surgery was found to stimulate the expression of genes that encode neurotrophins ( Bdnf, Ngf) and their receptor ( p75). It has been shown that ischemia influenced the expression of neurotrophins ( Bdnf, Ngf, Nt-3) and their receptors ( TrkB, TrkA, TrkC, p75) in brain structures outside the lesion focus, including the contralateral hemisphere. The downregulation of Bdnf and TrkB transcripts and Ngf and TrkA upregulation in the contralateral cortex on the first day of ischemia obviously reflected stress response. On day 3, Nt-3 transcription increased in all investigated structures outside the lesion focus. In the contralateral hemisphere, relative levels of TrkA and TrkC mRNA expression increased, while p75 expression decreased. Presumably, the observed changes in gene transcription serve to facilitate neuroplasticity and neural tissue regeneration. [ABSTRACT FROM AUTHOR]

Purpose: Tropomyosin-related kinase (Trk) receptors play critical roles in tumor development and are considered attractive targets for cancer therapy. We investigated correlations of the expression of TrkA, TrkB, and TrkC with clinicopathological features and outcomes in gastric cancer. Methods: Tumor samples were obtained from 221 patients with gastric cancer who underwent gastrectomy between 2003 and 2007. The expression of TrkA, TrkB, and TrkC was analyzed using immunohistochemical staining. The relationship of their expression to clinicopathological factors and outcomes was assessed. Results: High expression of TrkA, TrkB, or TrkC was significantly associated with histopathology ( p = 0.022, p < 0.001, and p < 0.001). High expression of TrkA was significantly correlated with variables related to tumor progression, including lymph node metastasis ( p = 0.024) and distant metastasis or recurrence ( p < 0.001). Distant metastasis or recurrence was found in a significantly higher proportion of patients with high expression of TrkC than in those with low expression ( p = 0.036). High expression of TrkA was significantly associated with poorer relapse-free survival (RFS) in univariate analysis ( p = 0.001). High expression of TrkA or TrkC was significantly associated with poorer disease-specific survival (DSS) in univariate analysis ( p < 0.001 and p = 0.008). In multivariate analysis, TrkA was an independent predictor of RFS [hazard ratio (HR), 2.294; 95 % confidence interval (CI), 1.309-4.032; p = 0.004] and DSS (HR, 2.146; 95 % CI, 1.195-3.861; p = 0.011). Expression of TrkB was not associated with RFS or DSS in univariate analysis. Conclusions: Our results demonstrated that TrkA expression was associated with tumor progression and poor survival, and was an independent predictor of poor outcomes in gastric cancer patients. [ABSTRACT FROM AUTHOR]

Background: Mammary analogue secretory carcinoma (MASC) is a recently described pathologic entity. We report the case of a patient with an initial diagnosis of salivary acinic cell carcinoma later reclassified as MASC after next-generation sequencing revealed an ETV6-NTRK3 fusion. Patients and methods: This alteration was targeted with the pan-Trk inhibitor entrectinib (Ignyta), which possesses potent in vitro activity against cell lines containing various NTRK1/2/3 fusions. Results: A dramatic and durable response was achieved with entrectinib in this patient, followed by acquired resistance that correlated with the appearance of a novel NTRK3 G623R mutation. Structural modeling predicts that this alteration sterically interferes with drug binding, correlating to decreased sensitivity to drug inhibition observed in cell-based assays. Conclusions: This first report of clinical activity with TrkC inhibition and the development of acquired resistance in an NTRK3-rearranged cancer emphasize the utility of comprehensive molecular profiling and targeted therapy for rare malignancies (NCT02097810). [ABSTRACT FROM AUTHOR]

Neurotrophin-3 (NT-3) is a secreted neurotrophic factor that binds neurotrophin receptor tyrosine kinase C (TrkC), which in turn binds to presynaptic protein tyrosine phosphatase σ (PTPσ) to govern excitatory synapse development. However, whether and how NT-3 cooperates with the TrkC-PTPσ synaptic adhesion pathway and TrkC-mediated intracellular signaling pathways in rat cultured neurons has remained unclear. Here, we report that NT-3 enhances TrkC binding affinity for PTPσ. Strikingly, NT-3 treatment bidirectionally regulates the synaptogenic activity of TrkC: at concentrations of 10 -25 ng/ml, NT-3 further enhanced the increase in synapse density induced by TrkC overexpression, whereas at higher concentrations, NT-3 abrogated TrkC-induced increases in synapse density. Semiquantitative immunoblotting and optogenetics-based imaging showed that 25 ng/ml NT-3 or light stimulation at a power that produced a comparable level of NT-3 (6.25μW) activated only extracellular signal-regulated kinase (ERK) and Akt, whereas 100 ng/ml NT-3 (light intensity, 25μW) further triggered the activation of phospholipase C-γ1 and CREB independently of PTPσ. Notably, disruption of TrkC intracellular signaling pathways, extracellular ligand binding, or kinase activity by point mutations compromised TrkC-induced increases in synapse density. Furthermore, only sparse, but not global, TrkC knock-down in cultured rat neurons significantly decreased synapse density, suggesting that intercellular differences in TrkC expression level are critical for its synapse-promoting action. Together, our data demonstrate that NT-3 is a key factor in excitatory synapse development that may direct higher-order assembly of the TrkC/ PTPσ complex and activate distinct intracellular signaling cascades in a concentration-dependent manner to promote competitionbased synapse development processes. [ABSTRACT FROM AUTHOR]

Neurotrophins, essential regulators of many aspects of neuronal differentiation and function, signal via four receptors, p75, TrkA, TrkB and TrkC. The three Trk paralogs are members of the LIG superfamily of membrane proteins, which share extracellular domains consisting of leucine-rich repeat and C2 Ig domains. Another LIG protein, LINGO-1 has been reported to bind and influence signaling of p75 as well as TrkA, TrkB and TrkC. Here we examine the manner in which LINGO-1 influences the function of TrkA, TrkB and TrkC. We report that Trk activation promotes Trk association with LINGO-1, and that this association promotes Trk degradation by a lysosomal mechanism. This mechanism resembles the mechanism by which another LIG protein, LRIG1, promotes lysosomal degradation of receptor tyrosine kinases such as the EGF receptor. We present evidence indicating that the Trk/LINGO-1 interaction occurs, in part, within recycling endosomes. We show that a mutant form of LINGO-1, with much of the extracellular domain deleted, has the capacity to enhance TrkA signaling in PC12 cells, possibly by acting as an inhibitor of Trk down-regulation by full length LINGO-1. We propose that LINGO-1 functions as a negative feedback regulator of signaling by cognate receptor tyrosine kinases including TrkA, TrkB and TrkC. [ABSTRACT FROM AUTHOR]

Neurotrophin-3 (NT-3) and its high-affinity receptor TrkC play crucial trophic roles in neuronal differentiation, axon outgrowth, and synapse development and plasticity in the nervous system. We demonstrated previously that postsynaptic TrkC functions as a glutamatergic synapse-inducing (synaptogenic) cell adhesion molecule trans-interacting with presynaptic protein tyrosine phosphatase σ (PTPσ). Given that NT-3 and PTPσ bind distinct domains of the TrkC extracellular region, here we tested the hypothesis that NT-3 modulates TrkC/PTPσ binding and synaptogenic activity. NT-3 enhanced PTPσ binding to cell surface-expressed TrkC and facilitated the presynapse-inducing activity of TrkC in rat hippocampal neurons. Imaging of recycling presynaptic vesicles combined with TrkC knockdown and rescue approaches demonstrated that NT-3 rapidly potentiates presynaptic function via binding endogenous postsynaptic TrkC in a tyrosine kinase-independent manner. Thus, NT-3 positively modulates the TrkC-PTPσ complex for glutamatergic presynaptic assembly and function independently from TrkC kinase activation. Our findings provide new insight into synaptic roles of neurotrophin signaling and mechanisms controlling synaptic organizing complexes. [ABSTRACT FROM AUTHOR]

Fear is an ancestral emotion, an intrinsic defensive response present in every organism. Although fear is an evolutionarily advantageous emotion, under certain pathologies such as panic disorder it might become exaggerated and non-adaptive. Clinical and preclinical work pinpoints that changes in cognitive processes, such as perception and interpretation of environmental stimuli that rely on brain regions responsible for high-level function, are essential for the development of fear-related disorders. This review focuses on the involvement of cognitive function to fear circuitry disorders. Moreover, we address how animal models are contributing to understand the involvement of human candidate genes to pathological fear and helping achieve progress in this field. Multidisciplinary approaches that integrate human genetic findings with state of the art genetic mouse models will allow to elucidate the mechanisms underlying pathology and to develop new strategies for therapeutic targeting. [ABSTRACT FROM AUTHOR]

Functional deficits following spinal cord injury (SCI) primarily attribute to loss of neural connectivity. We therefore tested if novel tissue engineering approaches could enable neural network repair that facilitates functional recovery after spinal cord transection (SCT). Rat bone marrow-derived mesenchymal stem cells (MSCs), genetically engineered to overexpress TrkC, receptor of neurotrophin-3 (NT-3), were pre-differentiated into cells carrying neuronal features via co-culture with NT-3 overproducing Schwann cells in 3-dimensional gelatin sponge (GS) scaffold for 14 days in vitro . Intra-GS formation of MSC assemblies emulating neural network (MSC-GS) were verified morphologically via electron microscopy (EM) and functionally by whole-cell patch clamp recording of spontaneous post-synaptic currents. The differentiated MSCs still partially maintained prototypic property with the expression of some mesodermal cytokines. MSC-GS or GS was then grafted acutely into a 2 mm-wide transection gap in the T9-T10 spinal cord segments of adult rats. Eight weeks later, hindlimb function of the MSC-GS-treated SCT rats was significantly improved relative to controls receiving the GS or lesion only as indicated by BBB score. The MSC-GS transplantation also significantly recovered cortical motor evoked potential (CMEP). Histologically, MSC-derived neuron-like cells maintained their synapse-like structures in vivo ; they additionally formed similar connections with host neurites (i.e., mostly serotonergic fibers plus a few corticospinal axons; validated by double-labeled immuno-EM). Moreover, motor cortex electrical stimulation triggered c-fos expression in the grafted and lumbar spinal cord cells of the treated rats only. Our data suggest that MSC-derived neuron-like cells resulting from NT-3-TrkC-induced differentiation can partially integrate into transected spinal cord and this strategy should be further investigated for reconstructing disrupted neural circuits. [ABSTRACT FROM AUTHOR]

Biological materials combined with genetically-modified neural stem cells (NSCs) are candidate therapy targeting spinal cord injury (SCI). Based on our previous studies, here we performed gelatin sponge (GS) scaffold seeded with neurotrophin-3 (NT-3) and its receptor TrkC gene modifying NSCs for repairing SCI. Eight weeks later, compared with other groups, neurofilament-200 and 5-hydroxytryptamine positive nerve fibers were more in the injury site of the N+T-NSCs group. Immunofluorescence staining showed the grafted NSCs could differentiate into microtubule associated protein (Map2), postsynaptic density (PSD95), and mouse oligodendrocyte special protein (MOSP) positive cells. The percentage of the Map2, PSD95, and MOSP positive cells in the N+T-NSCs group was higher than the other groups. Immuno-electron microscopy showed the grafted NSCs making contact with each other in the injury site. Behavioral analysis indicated the recovery of hindlimbs locomotion was better in the groups receiving cell transplant, the best recovery was found in the N+T-NSCs group. Electrophysiology revealed the amplitude of cortical motor evoked potentials was increased significantly in the N+T-NSCs group, but the latency remained long. These findings suggest the GS scaffold containing genetically-modified NSCs may bridge the injury site, promote axon regeneration and partial functional recovery in SCI rats. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1533-1545, 2015. [ABSTRACT FROM AUTHOR]