Transcription profiling of mouse Bax null versus NGF-Bax double null animals
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ABSTRACT: 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.
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 NGF–TrkA signaling whereas neurons with high NGF–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. Keywords: comparative gene expression analysis
Project description:The clinical use of Nerve Growth Factor (NGF) for neural regeneration has been hampered by pain sensitization side effects. NGF signals through the receptor tyrosine kinase TrkA and the co-receptor p75NTR; pain sensitization is thought to involve p75NTR. We sought to overcome this limitation by de novo design of a TrkA agonist that does not bind p75. We designed homodimeric TrkA engaging constructs that bring together two TrkA subunits in a variety of geometries, and identified those eliciting the strongest signaling. The resulting designed agonists are able to stimulate transdifferentiated neurons and neuroblastoma cell lines, leading to neurite outgrowth and neuronal differentiation, with considerably reduced transcription of inflammation and pain related genes. Although detailed in vivo characterization will be required to fully understand their therapeutic potential, these agonists are promising candidates for inducing neural regeneration with reduced pain side effects.
Project description:The clinical use of Nerve Growth Factor (NGF) for neural regeneration has been hampered by pain sensitization side effects. NGF signals through the receptor tyrosine kinase TrkA and the co-receptor p75NTR; We sought to overcome this limitation by de novo design of a TrkA agonist that does not bind p75. We designed homodimeric TrkA engaging constructs that bring together two TrkA subunits in a variety of geometrics, and identified those eliciting the strongest signaling. The resulting designed agonists are able to stimulate transdifferentiated neurons and neuroblastoma cell lines, leading to outgrowth of neurites and neuronal differentiation, with considerably reduced transcription of inflammation and pain related genes. Although detailed in vivo characterization will be required to fully understand their therapeutic potential, these agonists are promising candidates for inducing neural regeneration with reduced pain side effects.
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: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: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:Peripheral afferent neurons terminate at the surfaces of tendons, yet their role after injury beyond nociceptive functions remain unclear. Using transgenic animal models, sensory neurons were found to sprout after Achilles tendon injury in domains of Nerve growth factor (NGF) expression. Conditional deletion of Ngf in either myeloid or mesenchymal cell types led to tendon repair defects – findings phenocopied by inactivation of TrkA (Tropomyosin receptor kinase A) using a knockin mouse model. We sought to identify the signals modulated with neural TrkA inhibition. A combination of single cell and spatial transcriptomic analysis was performed on the Achilles injury site of TrkA^F592A animals and compared them to TrkA^WT.