Neurotrophic Tyrosine Kinase Receptor Type 2 Research Articles

Modification of a Selective NTRK2 Agonist and Confirmation of Activity in a Glaucoma-on-a-Chip Model.

RNYK is a selective agonist of the neurotrophic tyrosine kinase receptor type 2 (NTRK2) which has been screened from a phage-displayed peptide library. Its sequence is SGVYKVAYDWQH, similar to a native NTRK2 ligand, that is, brain-derived neurotrophic factor (BDNF). The current study was performed to recognize and confirm critical residues for RNYK activity in a glaucoma-on-a-chip model. We designed a modified RNYK (mRNYK) peptide based on hotspots of the RNYK sequence identified by alanine scanning. The critical residues consisted of tyrosine, valine, aspartic acid, and tryptophan (YVDW); however, lysine and glutamine were also maintained in the final sequence (YKVDWQ) for forming amide bonds and peptide dimerization. The affinity of mRNYK binding was confirmed by testing against NTRK2 receptors on the surface of ATRA-treated SH-SY5Y cells. The neuroprotective effect of mRNYK was also evaluated in cell culture after elevated pressure insult in a glaucoma-on-a-chip model. The primary amine on the lysine side-chain from one sequence (YKVDWQ) reacted with a γ-carboxamide group of glutamine from the other sequence, forming dimeric mRNYK. In silico, molecular dynamic simulations of the mRNYK-NTRK2 complex showed more stable and stronger interactions as compared to the RNYK-NTRK2 complex. In vitro, mRNYK demonstrated a neuroprotective effect on SH-SY5Y cells under normal and elevated pressure comparable to RNYK. The 50% effective concentration (logEC50) for mRNYK was 0.7009, which was better than RNYK with a logEC50 of 0.8318. The modified peptide studied herein showed improved stability over the original peptide (RNYK) and demonstrated potential for use as a BDNF agonist with neuroprotective properties for treatment of neurodegenerative disorders such as glaucoma.

Gene co-expression network and differential expression analyses of subcutaneous white adipose tissue reveal novel insights into the pathological mechanisms underlying ketosis in dairy cows

Ketosis is a common nutritional metabolic disease during the perinatal period in dairy cows. Although various risk factors have been identified, the molecular mechanism underlying ketosis remains elusive. In this study, subcutaneous white adipose tissue (sWAT) was biopsied for transcriptome sequencing on 10 Holstein cows with type II ketosis [blood β-hydroxybutyric acid (BHB) >1.4 mmol/L; Ket group] and another 10 cows without type II ketosis (BHB ≤1.4 mmol/L; Nket group) at d 10 after calving. Serum concentrations of nonesterified fatty acids (NEFA) and BHB, as indicators of excessive fat mobilization and circulating ketone bodies, respectively, were significantly higher in the Ket group than in the Nket group. Aspartate transaminase (AST) and total bilirubin (TBIL), as indicators of liver damage, were higher in the Ket group than in the Nket group. Weighted gene co-expression network analysis (WGCNA) of the sWAT transcriptome revealed modules significantly correlated with serum BHB, NEFA, AST, TBIL, and total cholesterol. The genes in these modules were enriched in the regulation of the lipid biosynthesis process. Neurotrophic tyrosine kinase receptor type 2 (NTRK2) was identified as the key hub gene by intramodular connectivity, gene significance, and module membership. Quantitative reverse transcription PCR analyses for these samples, as well as a set of independent samples, validated the downregulation of NTRK2 expression in the sWAT of dairy cows with type II ketosis. NTRK2 encodes tyrosine protein kinase receptor B (TrkB), which is a high-affinity receptor for brain-derived neurotrophic factor, suggesting that abnormal lipid mobilization in cows with type II ketosis might be associated with impaired central nervous system regulation of adipose tissue metabolism, providing a novel insight into the pathogenesis underlying type II ketosis in dairy cows.

Identification of potential inhibitors of tropomyosin receptor kinase B targeting CNS-related disorders and cancers

Tropomyosin receptor kinase B (TrkB), also known as neurotrophic tyrosine kinase receptor type 2 (NTRK2), is a protein that belongs to the family of receptor tyrosine kinases (RTKs). NTRK2 plays a crucial role in regulating the development and maturation of the central nervous system (CNS) and peripheral nervous system (PNS). Elevated TrkB expression levels observed in different pathological conditions make it a potential target for therapeutic interventions against neurological disorders, including depression, anxiety, Alzheimer’s disease, Parkinson’s disease, and certain types of cancer. Targeting TrkB using small molecule inhibitors is a promising strategy for the treatment of a variety of neurological disorders. In this research, a systematic virtual screening was carried out on phytoconstituents found in the IMPPAT library to identify compounds potentially inhibiting TrkB. The retrieved compounds from the IMPPAT library were first filtered using Lipinski’s rule of five. The compounds were then sorted based on their docking score and ligand efficiency. In addition, PAINS, ADMET, and PASS evaluations were carried out for selecting drug-like compounds. Finally, in interaction analysis, we found two phytoconstituents, Wedelolactone and 3,8-dihydroxy-1-methylanthraquinone-2-carboxylic acid (DMCA), which possessed considerable docking scores and specificity on the TrkB ATP-binding pocket. The selected compounds were further assessed employing molecular dynamics (MD) simulations and essential dynamics. The results revealed that the elucidated compounds bind well with the TrkB binding pocket and lead to fewer conformations fluctuations. This study highlighted using phytoconstituents, Wedelolactone and DMCA as starting leads in developing novel TrkB inhibitors. Communicated by Ramaswamy H. Sarma

Functional characterization and potential therapeutic avenues for variants in the NTRK2 gene causing developmental and epileptic encephalopathies.

Variants within the Neurotrophic Tyrosine Kinase Receptor Type 2 (NTRK2) gene have been discovered to play a role in developmental and epileptic encephalopathies, a group of debilitating conditions for which little is known about cause or treatment. Here, we determine the functional consequences of two variants: p.Tyr434Cys (Y434C) (located in the transmembrane domain) and p.Thr720Ile (T720I) (located in the catalytic domain). Wild-type and variant cDNAs were constructed and transfected into HEK293 cells. In cell culture, variant Y434C exhibited ligand-independent activation of tropomyosin-related kinase B (TRKB) signaling with an associated abnormal response to brain-derived neurotrophic factor (BDNF) stimulation and increased levels of phosphorylated extracellular signal-regulated kinase (ERK) and ETS like-1 protein (ELK1) activity. Expression of variant T720I resulted in decreased TRKB signaling with reduced mTor activity as determined by decreased levels of phosphorylated S6. With the deleterious mechanisms characterized, we utilized mediKanren (a novel artificial intelligence tool) to identify therapeutics to compensate for the pathological effects. Downregulation of TRKB through inhibition with mediKanren-predicted compound 1NM-PP1 led to decreased MEK activity. Upregulation of TRKB signaling by mediKanren-predicted valproic acid led to subsequent increase of mTor activity. Overall, our results provide further characterization of the pathogenicity of these two variants in the NTRK2 gene. Indeed, Y434C is the first patient-specific NTRK2 variant with demonstrated hypermorphic activity. Furthermore, we observed that variants Y434C and T720I result in distinct functional consequences that require distinct therapeutic strategies. These data suggest the possibility that unique mutations within different regions of the NTRK2 gene results in separate clinical presentations, representing distinct genetic disorders requiring unique therapeutics.

Systematic Identification of Circular RNA in Alzheimer’s Disease

Circular (circ)RNAs are an extensive family of RNAs in which the 3′ and 5′ ends are covalently linked. In humans, circRNAs have been implicated in a range of age‐associated pathologies, including Alzheimer’s Disease (AD), Parkinson’s Disease, and cancer. However, only a few of them have been functionally characterized. Given that circRNAs lack 5− and 3− ends and are refractory to exoribonuclease digestion, they have long half‐lives and can serve as effective ‘sponges’, binding cellular factors (RNAs and proteins) in a stable manner. One particular circRNA that is highly abundant in the human brain, ciRS‐7, was found to associate with and ‘sponge’ a specific microRNA, miR‐7, which is an important regulator of post‐transcriptional gene expression in the human brain. We hypothesize that many other circular RNAs may influence the gene expression programs in the AD brain through binding microRNAs or other molecules.Here, our primary goal was to identify all circRNAs relevant to AD using publicly available deep‐sequenced datasets and specifically designed bioinformatic and genomic tools and software. We analyzed four different publicly available data sets (n = 102 total brains) for the presence of circRNAs. We aligned the RNA sequencing data to the human genome (hg19 Ensembl v82) with aligners such as STAR and TopHat2, used CIRCexplorer2 to parse and annotate circRNA junctions in each sample, and processed these junctions through pipelines such as edgeR and DESeq2 (Fig. 1). After analyzing the junctions, we identified the body of each circRNA using the de novo assembly functions of CIRCexplorer2, which we then ran through the same edgeR and DESeq2 pipelines.The results reveal substantial differences in the abundance of circRNAs in AD brains relative to normal brains (Table 1). Moreover, these dysregulated circRNAs do not appear to be confined to one section of the brain, as they appear in the frontal lobe, hippocampus, and lateral temporal lobe. We propose that these circRNAs may represent possible diagnostic or prognostic factors. Assessment of their possible implication in AD pathogenesis is underway through the identification of circRNA‐interacting partners – RNA‐binding proteins and RNAs.differences in RNA content in control (age‐matched) and AD brain.Volcano plot showing differences in circular RNAs (also more and less abundant) in AD relative to control brain samples.Figure 1 Table showing the genes encoding the most commonly and differently expressed circRNAs associated with AD in published studies. Parent Gene Full circRNA Name Relation to Alzheimer’s DOCK1 hsa_circ_chr10_128768965_128780237_F Associated with axon function, neuroinflammation, spine morphogenesis, and neurite growth NTRK2 hsa_circ_chr9_87317073_87325706_F May be a genetic susceptibility gene contributing to AD pathology 1 KIF1B hsa_circ_chr1_10292307_10338186_F Transports synaptic vesicles necessary for nerve impulses DLG1 hsa_circ_chr3_196786759_196796131_R Increased expression shown to cause increased neuronal strength, affecting memory TRAPPC9 hsa_circ_chr8_141407718_141415797_R Associated with cognitive disability in multiple diseases (including autism, HD, etc.) APC hsa_circ_chr5_112154662_112163703_F Involved in synapse assembly between neurons 1Genetic association of neurotrophic tyrosine kinase receptor type 2 (NTRK2) With Alzheimer’s disease. ( PMID: 17918233) Chen Z… Go RC American journal of medical genetics. Part B, Neuropsychiatric genetics: the official publication of the International Society of Psychiatric Genetics 2008.

Brain-derived neurotrophic factor (BDNF) is expressed in buffalo (Bubalus bubalis) ovarian follicles and promotes oocyte maturation and early embryonic development

Brain-derived neurotrophic factor (BDNF) has been discovered and characterized for several decades, yet its expression pattern in non-neuronal tissues like ovary and potential mechanism during oocyte maturation are still poorly understood. Thus the present study was devised to determine the expression pattern and mechanism of BDNF during buffalo oocyte maturation. The results revealed that BDNF was presented at different stages of buffalo ovarian follicles as well as during oocyte maturation and early embryo development. BDNF’s receptor p75 was detected in granulosa cells, cumulus cells, oocytes, and early embryos, while another receptor neurotrophic tyrosine kinase receptor, type2 (NTRK2) was only identified in granulosa cells and cumulus cells. To determine the effect of BDNF on oocyte maturation and early embryo development, different concentrations (0, 1, 10, 100 ng/mL) of BDNF were added into the in vitro maturation media, respectively. It was divulged that 10 ng/mL BDNF promoted the in vitro maturation rate of buffalo oocytes and the blastocysts rate of embryos cultured in vitro (P < 0.05). Then through using NTRK2 inhibitor K-252a, we found BDNF and its receptor NTRK2 in cumulus cells played an essential role during oocyte maturation. Moreover, to further investigate the underlying mechanism by which BDNF enhances oocyte maturation, RT-qPCR was performed. 10 ng/mL BDNF treatment could decrease the expression level of apoptosis-related genes CCASP9, FAS, up-regulate the expression level of receptor gene NTRK2, cell proliferation-related genes CCNB1, PCNA, gap junction-related genes GJA4, GJA1 as well as cumulus cells expansion-related genes HAS2, PTX3 and TNFAIP6 (P < 0.05). Altogether, our results showed for the first time that BDNF was expressed throughout buffalo ovarian follicle development, oocyte maturation and early embryogenesis. Furthermore, BDNF treatment could improve the efficiency of buffalo oocyte maturation through regulating genes expression in cumulus cells and then promote early embryo development.

Peptide selected by phage display increases survival of SH-SY5Y neurons comparable to brain-derived neurotrophic factor.

Brain-derived neurotrophic factor (BDNF) is a well-known neuroprotectant and a potent therapeutic candidate for neurodegenerative diseases. However, there are several clinical concerns about its therapeutic applications. In the current study, we designed and developed BDNF-mimicking small peptides as an alternative to circumvent these problems. A phage-displayed peptide library was screened using BDNF receptor (neurotrophic tyrosine kinase receptor type2 [NTRK2]) and evaluated by ELISA. The peptide sequences showed similarity to loop2 of BDNF, they were recognized as discontinuous epitopes though. Interestingly, in silico molecular docking showed strong interactions between the peptide three-dimensional models and the surface residues of the NTRK2 protein at the IgC2 domain. A consensus peptide sequence was then synthesized to generate a mimetic construct (named as RNYK). The affinity binding and function of this construct was confirmed by testing against the native structure of NTRK2 in SH-SY5Y cells in vitro using flow-cytometry and MTT assays, respectively. RNYK at 5 ng/mL prevented neuronal degeneration of all- trans-retinoic acid-treated SH-SY5Y with equal efficacy to or even better than BDNF at 50 ng/mL.

Targeted exome sequencing for the identification of a protective variant against Internet gaming disorder at rs2229910 of neurotrophic tyrosine kinase receptor, type 3 (NTRK3): A pilot study.

Background and aimsInternet gaming disorder (IGD) has gained recognition as a potential new diagnosis in the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders, but genetic evidence supporting this disorder remains scarce.MethodsIn this study, targeted exome sequencing was conducted in 30 IGD patients and 30 control subjects with a focus on genes linked to various neurotransmitters associated with substance and non-substance addictions, depression, and attention deficit hyperactivity disorder.Resultsrs2229910 of neurotrophic tyrosine kinase receptor, type 3 (NTRK3) was the only single nucleotide polymorphism (SNP) that exhibited a significantly different minor allele frequency in IGD subjects compared to controls (p = .01932), suggesting that this SNP has a protective effect against IGD (odds ratio = 0.1541). The presence of this potentially protective allele was also associated with less time spent on Internet gaming and lower scores on the Young’s Internet Addiction Test and Korean Internet Addiction Proneness Scale for Adults.ConclusionsThe results of this first targeted exome sequencing study of IGD subjects indicate that rs2229910 of NTRK3 is a genetic variant that is significantly related to IGD. These findings may have significant implications for future research investigating the genetics of IGD and other behavioral addictions.

NTRK2 is an oncogene and associated with microRNA-22 regulation in human gastric cancer cell lines

In this study, we examined the roles of neurotrophic tyrosine kinase receptor type 2 (NTRK2) gene in regulating in vitro proliferation and invasion in human gastric cancer. Gene expression of NTRK2 was compared between non-carcinoma gastric epithelial cells and gastric cancer (GC) cells by quantitative RT-PCR (qRT-PCR). NTRK2 was either downregulated or upregulated in MKN-28 and SNU-719 cells. The effect of NTRK2 downregulation or upregulation on GC in vitro development was analyzed by qRT-PCR, western blot, proliferation assay, and invasion assay, respectively. The upstream regulator of NTRK2, microRNA-22 (miR-22), was evaluated by dual-luciferase assay. MiR-22 was then upregulated in MKN-28 and SNU-719 cells to examine its regulation on NTRK2 and its encoded protein, tyrosine kinase receptor B (TrkB). In miR-22-upregulated MKN-28 and SNU-719 cells, NTRK2 was further overexpressed to evaluate functional interaction between miR-22 and NTRK2 in GC. NTRK2 was aberrantly upregulated in GC cell lines than in normal gastric cells. In MKN-28 and SNU-719 cells, NTRK2 downregulation inhibited whereas NTRK2 upregulation promoted GC proliferation and invasion in vitro. MiR-22 was verified to be an inverse upstream regulator of NTRK2. In miR-22-upregulated MKN-28 and SNU-719 cells, NTRK2 overexpression partially reversed the miR-22-induced inhibition on cancer proliferation and invasion. NTRK2 is an oncogene and reversely associated with miR-22 in regulating in vitro cancer development in GC.

Investigating the associations between polymorphisms in the NTRK2 and NGFR genes and completed suicide in the Slovenian sample.

The most abundant neurotrophin in the mammalian brain is brain-derived neurotrophic factor (BDNF), which acts through binding to neurotrophic tyrosine kinase receptor type 2 (NTRK2) and to nerve growth factor receptor (NGFR). Our previous work showed an association of the single nucleotide polymorphism (SNP) rs6265 in the BDNF gene with completed suicide in the Slavic population. Therefore, we extended the investigation to the SNPs within NTRK2 and NGFR genes and searched for associations with the completed suicide phenotype. In 775 Caucasian individuals, namely, 486 suicide completers and 289 controls, we performed genotyping of five SNPs within the NTRK2 (rs11140714, rs1147198, rs1187323, rs10780691, and rs10868235) and six SNPs within the NGFR (rs2072446, rs7219709, rs7224806, rs734194, rs741071, and rs741072) genes. We did not find evidence for an association of the SNPs studied with the phenotype either on the single marker or on the haplotype level. To our knowledge, this is the first study that has examined SNPs in the NTRK2 and NGFR genes for associations with the completed suicide phenotype. However, our findings suggest that these SNPs may not be associated particularly with completed suicide in Slovenia, although they might have a relevant informative value as the study has been carried out on a sample from a population that has one of the highest suicide rates in the world.

Diagnostic utility of phosphorylated signal transducer and activator of transcription 5 immunostaining in the diagnosis of mammary analogue secretory carcinoma of the salivary gland: A comparative study of salivary gland cancers.

Mammary analogue secretory carcinoma (MASC) with an ETS variant gene 6 (ETV6)-neurotrophic tyrosine kinase receptor type 3 (NTRK3) translocation is a newly described type of salivary gland cancer. It is known that overexpression of signal transducer and activator of transcription 5a (STAT5a) occurs in secretory carcinoma of the breast and MASC, and STAT5a expression may be related to the ETV6-NTRK3 translocation. It was hypothesized that phosphorylated signal transducer and activator of transcription 5 (p-STAT5) might be specifically expressed in MASC of the salivary gland. The expression of p-STAT5 and mammaglobin (MMG) was examined with immunohistochemistry (IHC)/immunocytochemistry (ICC) in tissue sections from 58 salivary gland cancers (8 MASCs and 50 other salivary gland cancers) and in cytological smears from 17 salivary gland cancers (7 MASCs with paired histologic samples and 10 other salivary gland cancers). p-STAT5 IHC was clearly increased in MASC versus normal salivary gland tissue and other salivary gland cancers. p-STAT5 expression was found in 7 of 8 MASCs (87.5%) and in none of the 50 other salivary gland cancers (0%) by IHC. On cytology, p-STAT5 expression was found in all cases of MASC (7 of 7 or 100%) but in none of the 10 other salivary gland cancers (0%) by ICC. The expression rate of MMG by histology and cytology was higher than that of p-STAT5 in the other salivary gland cancers. p-STAT5 might be useful as a detection marker of MASC in the differential diagnosis of salivary gland cancers, and initial screening with p-STAT5 IHC/ICC, combined with auxiliary fluorescence in situ hybridization confirmation, is a reliable, economical approach to identifying MASC of the salivary gland.

Erratum] Effects of glucose-dependent insulinotropic polypeptide receptor knockout and a high-fat diet on cognitive function and hippocampal gene expression in mice.

RACHAEL R. LENNOX, CHARLOTTE MOFFETT, DAVID W. PORTER, NIGEL IRWIN, VICTOR A. GAULT and PETER R. FLATT Mol Med Rep 12:[Related article:] 1544–1548, 2015; DOI: 10.3892/mmr.2015.3447 After the publication of the article, the authors noted that there was an error regarding the author list. RACHAEL R. LENNOX and CHARLOTTE MOFFETT should actually be listed as RACHAEL LENNOX and R. CHARLOTTE MOFFETT. We apologize for the mistake and possible misunderstanding. The correct author list is as follows: RACHAEL LENNOX, R. CHARLOTTE MOFFETT, DAVID W. PORTER, NIGEL IRWIN, VICTOR A. GAULT and PETER R. FLATT.

Genetic association of the transcription of neuroplasticity-related genes and variation in stress-coping style.

IntroductionStress coping has been defined as the cognitive and behavioral efforts made to conquer, endure, or decrease external and internal demands and the conflicts between them. It has two main elements: the control or modification of the person–environment relationship causing the stress (i.e., problem-focused coping) and/or regulation of stressful feelings (i.e., emotion-focused coping). Research suggests that the expressions of brain-derived neurotrophic factor (BDNF) and neurotrophic tyrosine kinase receptor type 2 (NTRK2) play important roles in brain adaptation to investigate stress. To clarify the genetic basis of stress coping, we investigated the association of stress-coping strategies and social adaptation with single-nucleotide polymorphisms (SNPs) involved in neural plasticity, anxiety, and depression.MethodsIn 252 healthy controls (94 women; 158 men), we measured and estimated the stress-coping style using the Lazarus-type stress-coping inventory, ego aptitude scale (EAS), and social adaptation self-evaluation scale (SASS). We investigated one SNP of BDNF (rs6265, Val/Met) and five SNPs of NTRK2 (rs11140800, rs1187286, rs1867283, rs1147198, and rs10868235).ResultsWe observed significant associations between BDNF and emotion-focused strategies, seeking social support, self-control, and distancing. We also found significant associations between NTRK2 and cognitive strategies, problem-solving, confrontive- coping, seeking social support, distancing and positive reappraisal. Significant associations were also found between BDNF and critical attitudes and between NTRK2 and all seven ego-related factors on the EAS. In the SASS, the minor allele rs1867283 of NTRK2 had a significantly higher score than the heterozygote.ConclusionsThese findings may provide insights into the partial effects of genetic mutations in BDNF and NTRK2 on stress tolerance and personality.

Functional Analysis of Kinase-Activating Fusions in Ph-like Acute Lymphoblastic Leukemia

Introduction: Ph-like or BCR-ABL1-like B-progenitor acute lymphoblastic leukemia (ALL) is a high-risk subtype characterized by a gene expression profile similar to BCR-ABL1 ALL. The prevalence of Ph-like ALL rises from 10% in standard risk childhood ALL to over 25% in young adults. Next-generation sequencing of Ph-like ALL identified a variety of alterations involving kinase or cytokine receptor genes, including rearrangement, sequence mutation and copy number alterations. Chromosomal rearrangements in about one-third of Ph-like ALL cases create fusion genes of a variety of 5’ partners that involve ABL1-class genes (ABL1, ABL2, CSF1R and PDGFRB) or activate JAK family members (JAK2, TYK2, IL2RB) that are potentially amenable to treatment with ABL1-class or JAK-class tyrosine kinase inhibitors (TKIs). Notably, ABL2 (Abelson-related gene, ARG), a homolog of ABL1, has rarely been identified as a rearrangement partner in ALL. CSF1R (encoding the macrophage colony stimulating receptor) regulates the differentiation of macrophages, and is not normally expressed in lymphocytes. Likewise, rearrangements involving the JAK family member TYK2, the beta chain of the interleukin 2 cytokine receptor (IL2RB), and the neurotrophic tyrosine kinase receptor type 3 (NTRK3), have not been previously described in leukemia. The goals of this study were to assess the role of these kinase alterations in leukemogenesis, to determine the activation of signaling pathways, and to investigate the efficacy of TKIs.Methods: Kinase fusions were expressed in interleukin-3 dependent Ba/F3 cells, and co-expressed with the dominant negative isoform of IKAROS (IK6) in interleukin-7 dependent Arf-/- mouse pre-B cells. Xenograft models of 10 Ph-like ALL tumors - ETV6-ABL1, RANBP2-ABL1, PAG1-ABL2, RCSD1-ABL2, SSBP2-CSF1R, IGH-EPOR, ETV6-NTRK3, ATF7IP-JAK2, PAX5-JAK2 and ZEB2-PDGFRB - were generated by engrafting primary human leukemia cells into NOD-SCID IL2R gamma null (NSG) mice. Activation of kinase signaling was performed using phosphoflow cytometry analysis, and sensitivity to TKIs was assessed ex vivo and in vivo.Results: All kinase fusions (PAG1-ABL2, MYH9-IL2RB, ATF7IP-JAK2, ETV6-NTRK3 or MYB-TYK2) induced cytokine-independent proliferation of Ba/F3 cells. Mice transplanted with Arf-/- pre-B cells co-expressing IK6 and either RCSD1-ABL2 or SSBP2-CSF1R developed pre-B ALL (CD43+, B220+, CD19+, BP-1+ and IgM-) with a median latency of 36 and 40 days respectively, providing evidence that ABL2 and CSF1R fusions contribute to leukemogenesis.In human leukemic cells harvested from xenograft mice we observed distinct patterns of kinase signaling activation and TKI sensitivity for the different fusions. Xenograft cells expressing ABL1-class kinase fusions showed activation of STAT5 that was inhibited with imatinib or dasatinib. Phosphorylation of CRKL, a known target of ABL1 and ABL2, was only observed in cells expressing ABL1/2 fusions. Cells harboring ATF7IP-JAK2, PAX5-JAK2 or IGH-EPOR showed phosphorylation of STAT5 that was attenuated with the JAK2 inhibitor, ruxolitinib. In contrast, cells expressing ETV6-NTRK3 signaled through the MAPK pathway with constitutive pERK1/2 that was inhibited with the ALK-inhibitor, crizotinib. This TKI response profile was confirmed by cytotoxicity assays in xenograft cells, with ABL1-class fusions being sensitive to dasatinib (IC50 range 1-2nM), whilst cases harboring ATF7IP-JAK2 or EPOR rearrangement uniquely responded to ruxolitinib with IC50 values of 500nM and 850nM respectively. Interestingly, in human leukemic cells harboring the ETV6-NTRK3 fusion we observed selective inhibition with both crizotinib and the FLT3 inhibitor, lestaurtinib. Pre-clinical studies on three xenograft models of Ph-like ALL - ETV6-ABL1, RCSD1-ABL2 and SSBP2-CSF1R – showed significantly reduced leukemic burden in dasatinib treated mice (20mg/kg/day p.o) compared to vehicle treated mice.Conclusions: These data provide important insight on new targets of rearrangement in ALL and describe the first engineered mouse models of Ph-like B-ALL. Functional modeling of these alterations is essential to improve the clinical management of Ph-like ALL by identifying patients with specific genomic lesions at diagnosis and directing them to treatment with appropriate TKIs combined with chemotherapy, analogous to current treatment for BCR-ABL1 B-ALL. DisclosuresHunger:Bristol Myers Squibb: Consultancy.

Lixisenatide improves recognition memory and exerts neuroprotective actions in high-fat fed mice

The metabolic benefits of lixisenatide as an anti-diabetic agent are recognized but potential extra-pancreatic effects of this glucagon-like peptide-1 (GLP-1) mimetic in the brain are less well known. This study examines actions within the hippocampus following chronic 40-day peripheral administration of lixisenatide to high-fat fed mice with established obesity, insulin resistance and impaired cognition. Lixisenatide (50nmol/kg bw, twice-daily) resulted in marked improvements in glycemic status, insulin secretion and insulin sensitivity. Examination of pancreatic tissue revealed decreased islet area, increased islet number, and increased insulin content, with no evidence of pancreatic inflammation. Lixisenatide improved recognition memory during a novel object recognition task and this was associated with up-regulation of hippocampal expression of neurotrophic tyrosine kinase receptor type 2 (NTRK2) and mammalian target of rapamycin (mTOR) genes involved in modulating synaptic plasticity and long-term potentiation. Lixisenatide also enhanced progenitor cell proliferation and increased the number of immature neurons in the hippocampal dentate gyrus. These data indicate that lixisenatide is not only a new efficacious drug for treatment of diabetes but it also exerts favorable neuroprotective effects, reversing memory impairment in obesity-diabetes. Further clinical studies are necessary to fully assess potential beneficial actions of lixisenatide in the hippocampus and cognition in man.

Good proteins gone bad: brain-derived neurotrophic factor and its receptors in endometriotic implants and the role of estrogen

Previously we described brain-derived neurotrophic factor (BDNF) and its receptors in the eutopic endometrium. BDNF and its high affinity receptor, neurotrophic tyrosine kinase receptor type 2 (NTRK2), induce nerve growth, differentiation, and maintenance, but also activate the proliferation, adhesion, and angiogenesis pathways; each central to endometriosis. Thus, our objective was to determine the effect of hormones on BDNF in the uterus and ectopic endometriosis lesions.

Identification of kinase fusion oncogenes in post-Chernobyl radiation-induced thyroid cancers

Exposure to ionizing radiation during childhood markedly increases the risk of developing papillary thyroid cancer. We examined tissues from 26 Ukrainian patients with thyroid cancer who were younger than 10 years of age and living in contaminated areas during the time of the Chernobyl nuclear reactor accident. We identified nonoverlapping somatic driver mutations in all 26 cases through candidate gene assays and next-generation RNA sequencing. We found that 22 tumors harbored fusion oncogenes that arose primarily through intrachromosomal rearrangements. Altogether, 23 of the oncogenic drivers identified in this cohort aberrantly activate MAPK signaling, including the 2 somatic rearrangements resulting in fusion of transcription factor ETS variant 6 (ETV6) with neurotrophic tyrosine kinase receptor, type 3 (NTRK3) and fusion of acylglycerol kinase (AGK) with BRAF. Two other tumors harbored distinct fusions leading to overexpression of the nuclear receptor PPARγ. Fusion oncogenes were less prevalent in tumors from a cohort of children with pediatric thyroid cancers that had not been exposed to radiation but were from the same geographical regions. Radiation-induced thyroid cancers provide a paradigm of tumorigenesis driven by fusion oncogenes that activate MAPK signaling or, less frequently, a PPARγ-driven transcriptional program.

A large-scale candidate gene analysis of mood disorders

Despite proven heritability, little is known about the genetic architecture of mood disorders. Although a number of family and case-control studies have examined the genetics of mood disorders, none have carried out joint linkage-association studies and sought to validate the results with gene expression analyses in an independent cohort. We present findings from a large candidate gene study that combines linkage and association analyses using families and singletons, providing a systematic candidate gene investigation of mood disorder. For this study, 876 individuals were recruited, including 83 families with 313 individuals and 563 singletons. This large-scale candidate gene analysis included 130 candidate genes implicated in addictive and other psychiatric disorders. These data showed significant genetic associations for 28 of these candidate genes, although none remained significant after correction for multiple testing. To evaluate the functional significance of these 28 candidate genes in mood disorders, we examined the transcriptional profiles of these genes within the dorsolateral prefrontal cortex and anterior cingulate for 21 cases with mood disorders and 25 nonpsychiatric controls, and carried out a pathway analysis to identify points of high connectivity suggestive of particular molecular pathways that may be dysregulated. Two primary gene candidates were supported by the linkage-association, gene expression profiling, and network analysis: neurotrophic tyrosine kinase receptor, type 2 (NTRK2), and the opioid receptor, κ1 (OPRK1). This study supports a role for NTRK2 and OPRK1 signaling in the pathophysiology of mood disorder. The unique approach incorporating evidence from multiple experimental and computational modalities enhances confidence in these findings.

Neurotrophic Tyrosine Kinase Receptor Type 2 (NTRK2) Gene Associated with Treatment Response to Mood Stabilizers in Patients with Bipolar I Disorder

There is increasing evidence supporting the relationship between bipolar disorder (BP) and neurotrophin. The present study investigated the relationship between neurotrophic tyrosine kinase receptor type 2 (NTRK2) gene polymorphisms and bipolar I disorder (BP I) susceptibility and treatment response to mood stabilizers (lithium or valproate). Two-hundred eighty-four patients who met the DSM-IV criteria for BP I and 295 matched healthy controls were enrolled into this study. TaqMan® SNP genotyping assays were applied to genotype three NTRK2 gene polymorphisms (rs2769605, rs1565445, rs1387923). Our study showed a significant allelic association between NTRK2 gene polymorphism rs2769605 and treatment response to mood stabilizers in BP I patients (t = -2.53, P = 0.01). However, no significant association between NTRK2 gene polymorphisms and BP I susceptibility was observed after correcting for multiple comparisons. The results suggest that the NTRK2 gene polymorphism likely plays an essential role in treatment response to mood stabilizers in Han Chinese BP I patients.

Poster #46 ALTERED WHITE MATTER CONNECTIONS IN NEVER-MEDICATED PATIENTS WITH SCHIZOPHRENIA

Polymorphisms in the brain-derived neurotrophic factor (BDNF) gene and its receptor neurotrophic tyrosine kinase receptor type 2 (NTRK2) have been implicated in mood disorders. The aim of this study was to examine whether the NTRK2 and BDNF polymorphisms impact brain white matter connections in major depressive disorder and whether they may also have an interactive effect with environmental stress in the form of early life adversity.The study group comprised 45 depressed patients and 45 age- and gender-matched control subjects. High angular resolution diffusion images were obtained and analyzed using tract-based spatial statistics. Analysis of a single nucleotide polymorphism in the BDNF (rs6265/Valine66Methionine) and NTRK2 (rs11140714) genes was performed.An interactive effect was found between NTRK2 and depression diagnosis maximally affecting the cingulum. Depressed patients homozygous for the A allele of NTRK2 showed significantly reduced fractional anisotropy compared with depressed patients with at least one copy of the G allele or control subjects with either the A/A or G carrier genotypes in the left and right corona radiata, left uncinate fasciculus, left inferior fronto-occipital fasciculus, left cerebral peduncle, posterior thalamic radiation, and middle cerebral peduncle. Significantly smaller gray matter volume was seen in frontal lobe regions in patients homozygous for the A allele.Polymorphisms in NTRK2 gene increase risk of architectural changes in several brain regions involved in emotional regulation.