Project description:Background: Though exosomes, as the by-products of human umbilical cord mesenchymal stem cells (hUC-MSCs), have been demonstrated to be an effective therapy for traumatic spinal cord injury (SCI), it remains unclear through which manner exosomes act. Aim: In order to figure out whether exosomes attenuate lesion size of SCI by the amelioration of neuronal injury triggered by secondary inflammatory storm and induction of inner motivation of neurite outgrowth, we designed and performed this experiment. Methods: We determined absolute contents of all exosomal miRNAs and investigated the potential mechanisms of miR-199a-3p/145-5p in inducing neurite outgrowth in vivo and vitro. Results: miR-199a-3p/145-5p, which were relatively top-ranking miRNAs in exosomes, promoted PC12 cells differentiation suppressed by lipopolysaccharide (LPS) in vitro through the modulation of NGF/TrkA pathway. We also demonstrated that Cblb was the direct target of miR-199a-3p and Cbl was the direct target of miR-145-5p. Cblb and Cbl genes knock down revealed that TrkA ubiquitylation level significantly decreased, subsequently, activating the NGF/TrkA downstream pathways Akt and Erk. In return, overexpression of Cblb and Cbl suggested that TrkA ubiquitylation level significantly increased, subsequently, inactivating the NGF/TrkA downstream pathways Akt and Erk. Western blot and co-immunoprecipitation confirmed the direct interaction between TrkA and Cblb, TrkA and Cbl. In vivo experiment, exosomal miR-199a-3p/145-5p were found to up-regulate TrkA expression in the lesion site and promote locomotor function of SCI rats as well. Conclusion: In summary, our study suggested that hUC-MSCs derived exosomes may treat SCI by transferring miR-199a-3p/145-5p to neurons, and modulating TrkA ubiquitylation, and strengthening the NGF/TrkA signaling pathway in SCI rats.
Project description:We used quantitative mass spectrometry-based proteomics to unravel global nerve growth factor (NGF)-induced TrkA signaling dynamics at the interactome, phosphoproteome and proteome level. A tetracycline-inducible system for TrkA expression was generated in the human neuroblastoma cell line, SH-SY5Y. TrkA-induced cells were stimulated with NGF for different time points to follow phosphoproteome, interactome and proteome changes on a temporal scale. In a triple SILAC setup (Light: Lys0,Arg0; Medium: Lys4,Arg6; and Heavy: Lys8,Arg10), the samples were stimulated with NGF as indicated. Phosphoproteome: 0, 10, 45 min and 0, 120, 120 min+cycloheximide. Interactome: 0, 5, 10 min. Proteome: 0, 24, 48 h. All experiments were performed as biological replicates.
Project description:Melanomas are generated from melanocytes, the neural crest derivatives sharing a neuroectodermal origin with the nervous system. In investigating whether immune privilege of the nervous system might be exploited by melanoma, we found that nerve growth factor (NGF) exerts both melanoma cell-intrinsic and -extrinsic immunosuppression. In melanoma cells, autocrine NGF engages TrkA receptor to desensitize IFN-gammasignaling, leading to T and NK cell exclusion. In effector T cells, which upregulate surface TrkA expression upon T cell receptor (TCR) activation, paracrine NGF dampens TCR signaling and effector function. Targeting NGF genetically or pharmacologically with larotrectinib sensitizes melanoma responsiveness to immune checkpoint blockade (ICB) therapy for tumor eradication and induces durable protection by eliciting robust memory of low-affinity T cells. Together, these findings uncover a comprehensive mechanism through which the NGF-TrkA axis suppresses anti-tumor T cell immunity, thus providing a novel mode of action to repurpose larotrectinib for immune sensitization. Moreover, by enlisting low-affinity tumor-specific T cells, anti-NGF reduces acquired resistance to ICB therapy and prevents melanoma recurrence.
Project description:Melanomas are generated from melanocytes, the neural crest derivatives sharing a neuroectodermal origin with the nervous system. In investigating whether immune privilege of the nervous system might be exploited by melanoma, we found that nerve growth factor (NGF) exerts both melanoma cell-intrinsic and -extrinsic immunosuppression. In melanoma cells, autocrine NGF engages TrkA receptor to desensitize IFN-gammasignaling, leading to T and NK cell exclusion. In effector T cells, which upregulate surface TrkA expression upon T cell receptor (TCR) activation, paracrine NGF dampens TCR signaling and effector function. Targeting NGF genetically or pharmacologically with larotrectinib sensitizes melanoma responsiveness to immune checkpoint blockade (ICB) therapy for tumor eradication and induces durable protection by eliciting robust memory of low-affinity T cells. Together, these findings uncover a comprehensive mechanism through which the NGF-TrkA axis suppresses anti-tumor T cell immunity, thus providing a novel mode of action to repurpose larotrectinib for immune sensitization. Moreover, by enlisting low-affinity tumor-specific T cells, anti-NGF reduces acquired resistance to ICB therapy and prevents melanoma recurrence.
Project description:We used quantitative mass spectrometry-based proteomics to unravel global nerve growth factor (NGF)-induced TrkA signaling dynamics at the interactome, phosphoproteome and proteome level. A tetracycline-inducible system for TrkA expression was generated in the human neuroblastoma cell line, SH-SY5Y. TrkA-induced cells were stimulated with NGF for different time points to follow phosphoproteome, interactome and proteome changes on a temporal scale. In a triple SILAC setup (Light: Lys0,Arg0; Medium: Lys4,Arg6; and Heavy: Lys8,Arg10), the samples were stimulated with NGF as indicated. Phosphoproteome: 0, 10, 45 min and 0, 120, 120 min+cycloheximide. Interactome: 0, 5, 10 min. Proteome: 0, 24, 48 h. All experiments were performed as biological replicates.
Project description:Melanomas are generated from melanocytes, the neural crest derivatives sharing a neuroectodermal origin with the nervous system. In investigating whether immune privilege of the nervous system might be exploited by melanoma, we found that nerve growth factor (NGF) exerts both melanoma cell-intrinsic and -extrinsic immunosuppression. In melanoma cells, autocrine NGF engages TrkA receptor to desensitize IFN-gammasignaling, leading to T and NK cell exclusion. In effector T cells, which upregulate surface TrkA expression upon T cell receptor (TCR) activation, paracrine NGF dampens TCR signaling and effector function. Targeting NGF genetically or pharmacologically with larotrectinib sensitizes melanoma responsiveness to immune checkpoint blockade (ICB) therapy for tumor eradication and induces durable protection by eliciting robust memory of low-affinity T cells. Together, these findings uncover a comprehensive mechanism through which the NGF-TrkA axis suppresses anti-tumor T cell immunity, thus providing a novel mode of action to repurpose larotrectinib for immune sensitization. Moreover, by enlisting low-affinity tumor-specific T cells, anti-NGF reduces acquired resistance to ICB therapy and prevents melanoma recurrence.
Project description:Melanomas are generated from melanocytes, the neural crest derivatives sharing a neuroectodermal origin with the nervous system. In investigating whether immune privilege of the nervous system might be exploited by melanoma, we found that nerve growth factor (NGF) exerts both melanoma cell-intrinsic and -extrinsic immunosuppression. In melanoma cells, autocrine NGF engages TrkA receptor to desensitize IFN-gamma signaling, leading to T and NK cell exclusion. In effector T cells, which upregulate surface TrkA expression upon T cell receptor (TCR) activation, paracrine NGF dampens TCR signaling and effector function. Targeting NGF genetically or pharmacologically with larotrectinib sensitizes melanoma responsiveness to immune checkpoint blockade (ICB) therapy for tumor eradication and induces durable protection by eliciting robust memory of low-affinity T cells. Together, these findings uncover a comprehensive mechanism through which the NGF-TrkA axis suppresses anti-tumor T cell immunity, thus providing a novel mode of action to repurpose larotrectinib for immune sensitization. Moreover, by enlisting low-affinity tumor-specific T cells, anti-NGF reduces acquired resistance to ICB therapy and prevents melanoma recurrence.
Project description:BackgroundAlthough exosomes, as byproducts of human umbilical cord mesenchymal stem cells (hUC-MSCs), have been demonstrated to be an effective therapy for traumatic spinal cord injury (SCI), their mechanism of action remains unclear.MethodsWe designed and performed this study to determine whether exosomes attenuate the lesion size of SCI by ameliorating neuronal injury induced by a secondary inflammatory storm and promoting neurite outgrowth. We determined the absolute levels of all exosomal miRNAs and investigated the potential mechanisms of action of miR-199a-3p/145-5p in inducing neurite outgrowth in vivo and in vitro.ResultsmiR-199a-3p/145-5p, which are relatively highly expressed miRNAs in exosomes, promoted PC12 cell differentiation suppressed by lipopolysaccharide (LPS) in vitro through modulation of the NGF/TrkA pathway. We also demonstrated that Cblb was a direct target of miR-199a-3p and that Cbl was a direct target of miR-145-5p. Cblb and Cbl gene knockdown resulted in significantly decreased TrkA ubiquitination levels, subsequently activating the NGF/TrkA downstream pathways Akt and Erk. Conversely, overexpression of Cblb and Cbl was associated with significantly increased TrkA ubiquitination level, subsequently inactivating the NGF/TrkA downstream pathways Akt and Erk. Western blot and coimmunoprecipitation assays confirmed the direct interaction between TrkA and Cblb and TrkA and Cbl. In an in vivo experiment, exosomal miR-199a-3p/145-5p was found to upregulate TrkA expression at the lesion site and also promote locomotor function in SCI rats.ConclusionsIn summary, our study showed that exosomes transferring miR-199a-3p/145-5p into neurons in SCI rats affected TrkA ubiquitination and promoted the NGF/TrkA signaling pathway, indicating that hUC-MSC-derived exosomes may be a promising treatment strategy for SCI.
Project description:Nerve growth factor (NGF) is a neurotrophin that plays an important role in regulating the survival, growth, and differentiation of sympathetic neurons. Many in vitro studies indicate that Egr transcription factors are coupled to NGF signaling and are essential signaling mediators of NGF-dependent differentiation of sympathetic neurons, such as neuroblastoma cells and pheochromocytoma cells. Mice that are deficient for both Egr1 and Egr3 have profound sympathetic nerve system defects, including abnormal neuron degeneration and impaired differentiation (unpublished observations). To further understand the role of Egr genes in sympathetic neuron development, it is necessary to examine the signal transduction pathways involved in NGF-mediated Egr-dependent gene regulation. The results will be helpful in understanding the pathobiology of those diseases related to aberrant sympathetic neuron differentiation, such as neuroblastoma and dysautonomias, and may provide new insights into therapies for these refractory diseases. To identify NGF-mediated Egr-dependent target genes in human SH-SY5Y/TrkA neuroblastoma cells: Many potential Egr target genes have been described over the years. However, very few have been characterized to be involved in NGF-mediated sympathetic neuron differentiation. In order to further understand the role of Egr genes in sympathetic neuron development, it is necessary to examine the signal transduction pathways involved in NGF-mediated Egr-dependent gene regulation. Egr1 and Egr3 are rapidly induced after NGF treatment and Egr1 is involved in activation of the differentiation marker gene NPY in SH-SY5Y/TrkA cells. Therefore, SH-SY5Y/TtrkA cells appear to be an excellent model system to study the role of Egr transcription factors in sympathetic neuron differentiation in vitro. A dominant negative Egr molecule that specifically blocks transcriptional activity mediated by Egr transcription factors will be used in this study to identify Egr-dependent target genes. Egr1 and Egr3 are rapidly induced after NGF treatment in human SH-SY5Y/TrkA neuroblastoma cells, which in turn differentiate into sympathetic-like neurons. We hypothesize that Egr transcription factors are involved in activating downstream signaling pathways during NGF mediated differentiation of SH-SY5Y/TrkA cells. Moreover, we hypothesize that by using a dominant negative Egr (dnEgr) molecule that blocks all Egr mediated gene transcription and Affymetrix microarray analysis, it will be possible to identify NGF-mediated Egr transcription dependent gene regulatory networks that may be involved in growth and differentiation of neuroblastoma. An unbiased approach to understanding these gene regulatory networks may lead to new insights relating to NGF signaling involved in neuronal growth and differentiation. Human neuroblastoma SH-SY5Y/TrkA cells will be infected with either dnEgr-expressing adenovirus (SH-SY5Y/TrkA-dnEgr) or with EGFP-expressing control adenovirus (SH-SY5Y/TrkA-EGFP). Equivalent infection efficiency and lack of viral toxicity will be verified by EGFP fluorescence microscopy 24 hours after infection and the cells will be treated with NGF (100 ng/ml). Total RNA will be extracted from SH-SY5Y/TrkA (uninfected), SH-SY5Y/TrkA-dnEgr, and SH-SY5Y/TrkA-EGFP cells treated with NGF for 0, 1 hour and 3 hours. Total RNA will be prepared from all of the samples and a portion subjected to real-time PCR analysis to ensure that NGF mediated Egr gene induction was not altered by the context of viral infection. Pilot experiments demonstrate that Egr genes are still induced in the context of viral infection greater than 100-fold. Egr1 mRNA peak expression is known to occur at 1 hour and decrease by 3 hours after NGF treatment in all of the samples. The peak expression of Egr target genes is expected to occur later than Egr1 peak expression since Egr1 proteins need to be expressed first to initiate the transcription of target promoters. Therefore, the RNA samples from SH-SY5Y/TrkA-dnEgr and SH-SY5Y/TrkA-EGFP treated with NGF for 3 hours will be used to probe Affymetrix high-density human genome U133 Plus 2.0 Arrays to identify differentially expressed genes. RNA amplification for probe synthesis should not be necessary since we will provide 10 ug of intact total RNA for each sample. We will provide three sets of samples to perform the comparative microarray analysis twice from different starting materials and a nine-way comparative analysis of the data will be performed. We expect that cells containing high levels of dnEgr will inhibit NGF mediated Egr-dependent target gene expression and that these gene networks should be identifiable when compared to EGFP infected cells that have normal Egr gene transcriptional activity. Experiment Overall Design: as above
Project description:We report that developmental competition between sympathetic neurons for survival is critically dependent on a sensitization process initiated by target innervation and mediated by a series of feedback loops. Target-derived nerve growth factor (NGF) promoted expression of its receptor TrkA in neurons and prolonged TrkA-mediated signals. NGF also controlled expression of brain derived neurotrophic factor (BDNF) and neurotrophin-4 (NT4), which, through the receptor p75, can kill neighboring neurons with low retrograde NGFâ??TrkA signaling whereas neurons with high NGFâ??TrkA signaling are protected. Perturbation of any of these feedback loops disrupts the dynamics of competition. We suggest that three target-initiated events are essential for rapid and robust competition between neurons: sensitization, paracrine apoptotic signaling, and protection from such effects. Experiment Overall Design: This experiment examine gene expression differences in superior cervical ganglia fro P0 bax null versus NGF-Bax double null animals. The Bax genotype was used in order to prevent the neuronal cell death normally observed in the NGF null animal.