The Experts below are selected from a list of 3351 Experts worldwide ranked by ideXlab platform
Jane E. Johnson - One of the best experts on this subject based on the ideXlab platform.
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ASCL1 regulates neurodevelopmental transcription factors and cell cycle genes in brain tumors of glioma mouse models.
Glia, 2020Co-Authors: Tou Yia Vue, Mark D. Borromeo, Rahul K. Kollipara, Tomoyuki Mashimo, Tyler Smith, Robert Bachoo, Dennis K. Burns, Jane E. JohnsonAbstract:Glioblastomas (GBMs) are incurable brain tumors with a high degree of cellular heterogeneity and genetic mutations. Transcription factors that normally regulate neural progenitors and glial development are aberrantly coexpressed in GBM, conferring cancer stem-like properties to drive tumor progression and therapeutic resistance. However, the functional role of individual transcription factors in GBMs in vivo remains elusive. Here, we demonstrate that the basic-helix-loop-helix transcription factor ASCL1 regulates transcriptional targets that are central to GBM development, including neural stem cell and glial transcription factors, oncogenic signaling molecules, chromatin modifying genes, and cell cycle and mitotic genes. We also show that the loss of ASCL1 significantly reduces the proliferation of GBMs induced in the brain of a genetically relevant glioma mouse model, resulting in extended survival times. RNA-seq analysis of mouse GBM tumors reveal that the loss of ASCL1 is associated with downregulation of cell cycle genes, illustrating an important role for ASCL1 in controlling the proliferation of GBM.
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subtype specific secretomic characterization of pulmonary neuroendocrine tumor cells
Nature Communications, 2019Co-Authors: Xudong Wang, Trisha K. Savage, Kenneth Huffman, John D. Minna, Melanie H. Cobb, Qing Ding, Noelle S Williams, Jane E. JohnsonAbstract:Pulmonary neuroendocrine (NE) cancer, including small cell lung cancer (SCLC), is a particularly aggressive malignancy. The lineage-specific transcription factors Achaete-scute homolog 1 (ASCL1), NEUROD1 and POU2F3 have been reported to identify the different subtypes of pulmonary NE cancers. Using a large-scale mass spectrometric approach, here we perform quantitative secretome analysis in 13 cell lines that signify the different NE lung cancer subtypes. We quantify 1,626 proteins and identify IGFBP5 as a secreted marker for ASCL1High SCLC. ASCL1 binds to the E-box elements in IGFBP5 and directly regulates its transcription. Knockdown of ASCL1 decreases IGFBP5 expression, which, in turn, leads to hyperactivation of IGF-1R signaling. Pharmacological co-targeting of ASCL1 and IGF-1R results in markedly synergistic effects in ASCL1High SCLC in vitro and in mouse models. We expect that this secretome resource will provide the foundation for future mechanistic and biomarker discovery studies, helping to delineate the molecular underpinnings of pulmonary NE tumors.
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ASCL1 regulates proliferation of NG2-glia in the embryonic and adult spinal cord.
Glia, 2018Co-Authors: Demetra P. Kelenis, Jane E. Johnson, Emma Hart, Morgan Edwards-fligner, Tou Yia VueAbstract:NG2-glia are highly proliferative oligodendrocyte precursor cells (OPCs) that are widely distributed throughout the central nervous system (CNS). During development, NG2-glia predominantly differentiate into oligodendrocytes (OLs) to myelinate axon fibers, but they can also remain as OPCs persisting into the mature CNS. Interestingly, NG2-glia in the gray matter (GM) are intrinsically different from those in the white matter (WM) in terms of proliferation, differentiation, gene expression, and electrophysiological properties. Here we investigate the role of the transcriptional regulator, ASCL1, in controlling NG2-glia distribution and development in the GM and WM. In the spinal cord, ASCL1 levels are higher in WM NG2-glia than those in the GM. This differential level of ASCL1 in WM and GM NG2-glia is maintained into adult stages. Long-term clonal lineage analysis reveals that the progeny of single ASCL1+ oligodendrocyte progenitors (OLPs) and NG2-glia are primarily restricted to the GM or WM, even though they undergo extensive proliferation to give rise to large clusters of OLs in the postnatal spinal cord. Conditional deletion of ASCL1 specifically in NG2-glia in the embryonic or adult spinal cord resulted in a significant reduction in the proliferation but not differentiation of these cells. These findings illustrate that ASCL1 is an intrinsic regulator of the proliferative property of NG2-glia in the CNS.
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the epithelial sodium channel αenac is a downstream therapeutic target of ASCL1 in pulmonary neuroendocrine tumors
Translational Oncology, 2018Co-Authors: Min He, Mark D. Borromeo, Jane E. Johnson, Luc Girard, John D. Minna, Adi F. Gazdar, Sachith Gallolu Kankanamalage, Melanie H. CobbAbstract:Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma, designated as a recalcitrant cancer by the National Cancer Institute, in urgent need of new rational therapeutic targets. Previous studies have determined that the basic helix-loop-helix transcription factor achaete-scute homolog 1 (ASCL1) is essential for the survival and progression of a fraction of pulmonary neuroendocrine cancer cells, which include both SCLC and a subset of non-SCLC. Previously, to understand how ASCL1 initiates tumorigenesis in pulmonary neuroendocrine cancer and identify the transcriptional targets of ASCL1, whole-genome RNA-sequencing analysis combined with chromatin immunoprecipitation-sequencing was performed with a series of lung cancer cell lines. From this analysis, we discovered that the gene SCNN1A, which encodes the alpha subunit of the epithelial sodium channel (αENaC), is highly correlated with ASCL1 expression in SCLC. The product of the SCNN1A gene ENaC can be pharmacologically inhibited with amiloride, a drug that has been used clinically for close to 50 years. Amiloride inhibited growth of ASCL1-dependent SCLC more strongly than ASCL1-independent SCLC in vitro and slowed growth of ASCL1-driven SCLC in xenografts. We conclude that SCNN1A/αENaC is a direct transcriptional target of the neuroendocrine lung cancer lineage oncogene ASCL1 that can be pharmacologically targeted with antitumor effects.
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TMOD-12THE FUNCTION OF ACHAETE-SCUTE HOMOLOG 1 (ASCL1) IN GLIOBLASTOMA MULTIFORME
Neuro-Oncology, 2015Co-Authors: Tou Yia Vue, Mark D. Borromeo, Rahul K. Kollipara, Tomoyuki Mashimo, Tyler Smith, Robert Bachoo, Jane E. JohnsonAbstract:Glioblastoma multiforme (GBM) are incurable brain tumors that account for the majority of high-grade gliomas in the central nervous system (CNS). Currently, therapeutic approaches targeted at genomic alterations are ineffective in stopping these tumors and prognosis for GBM patients remains poor. Interestingly, many of the genes that are upregulated in GBM are transcription factors that are normally expressed in neural progenitor or stem cells. One such factor is the proneural factor Achaete-Scute Homolog 1(ASCL1), which plays a crucial role in cell fate specification, differentiation, and progenitor cell maintenance. It is possible that the aberrant expression of ASCL1 in GBM may bestowed upon tumor cells with “stem cell-like” property and the ability to develop resistance to chemotherapy and radiation. Indeed, ASCL1 has been shown to be required for the survival of a number of lung cancers with neuroendocrine features. Yet, to date the direct contribution and requirement of ASCL1 in GBM development in vivo remains unclear. In this study, we showed that ASCL1 is expressed in early stage as well as terminal stage brain tumors of a GBM mouse model. ChIP-seq shows that ASCL1 binds to about 9,800 sites within the genome associated with genes known to regulate diverse biological processes such as those involved in neural stem cell maintenance, inhibition of neural stem cell differentiation, and cellular response to vascular endothelial growth factor (VEGF). Conditional knock-out of ASCL1 (ASCL1-CKO) significantly improved the survival time of the GBM mouse model. Uniquely, RNA-seq gene expression profiling revealed that ASCL1+ tumors of the GBM mouse model closely resemble the proneural human GBM subtype, whereas ASCL1-CKO tumors resemble that of the mesenchymal GBM subtype. Collectively, these findings demonstrate a critical role for ASCL1, a single factor, in regulating GBM development and subtype, and may serve as a potential target for therapeutic purposes.
Thomas A Reh - One of the best experts on this subject based on the ideXlab platform.
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Developmental changes in the accessible chromatin, transcriptome and ASCL1-binding correlate with the loss in Müller Glial regenerative potential
Scientific reports, 2020Co-Authors: Leah S. Vandenbosch, Matthew S Wilken, Kristen E Cox, Connor Finkbeiner, Marcus J. Hooper, Laura Chipman, Stefanie G. Wohl, Thomas A RehAbstract:Diseases and damage to the retina lead to losses in retinal neurons and eventual visual impairment. Although the mammalian retina has no inherent regenerative capabilities, fish have robust regeneration from Muller glia (MG). Recently, we have shown that driving expression of ASCL1 in adult mouse MG stimulates neural regeneration. The regeneration observed in the mouse is limited in the variety of neurons that can be derived from MG; ASCL1-expressing MG primarily generate bipolar cells. To better understand the limits of MG-based regeneration in mouse retinas, we used ATAC- and RNA-seq to compare newborn progenitors, immature MG (P8-P12), and mature MG. Our analysis demonstrated developmental differences in gene expression and accessible chromatin between progenitors and MG, primarily in neurogenic genes. Overexpression of ASCL1 is more effective in reprogramming immature MG, than mature MG, consistent with a more progenitor-like epigenetic landscape in the former. We also used ASCL1 ChIPseq to compare the differences in ASCL1 binding in progenitors and reprogrammed MG. We find that bipolar-specific accessible regions are more frequently linked to bHLH motifs and ASCL1 binding. Overall, our analysis indicates a loss of neurogenic gene expression and motif accessibility during glial maturation that may prevent efficient reprogramming.
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stat pathway activation limits the ASCL1 mediated chromatin remodeling required for neural regeneration from muller glia in adult mouse retina
bioRxiv, 2019Co-Authors: Nikolas L. Jorstad, Matthew S Wilken, Levi Todd, Paul A. Nakamura, Nicholas Radulovich, Marcus J. Hooper, Alex Chitsazan, Brent A. Wilkerson, Fred Rieke, Thomas A RehAbstract:Abstract Muller glia can serve as a source for retinal regeneration in some non-mammalian vertebrates. Recently we found that this process can be induced in mouse Muller glia after injury, by combining transgenic expression of the proneural transcription factor ASCL1 and the HDAC inhibitor TSA. However, new neurons are only generated from a subset of Muller glia in this model, and identifying factors that limit ASCL1-mediated MG reprogramming could potentially make this process more efficient, and potentially useful clinically. One factor that limits neurogenesis in some non-mammalian vertebrates is the STAT pathway activation that occurs in Muller glia in response to injury. In this report, we tested whether injury induced STAT activation hampers the ability of ASCL1 to reprogram Muller glia into retinal neurons. Using a STAT inhibitor, in combination with our previously described reprogramming paradigm, we found a large increase in the ability of Muller glia to generate neurons, similar to those we described previously. Single-cell RNA-seq showed that the progenitor-like cells derived from ASCL1-expressing Muller glia have a higher level of STAT signaling than those that become neurons. Using ASCL1 ChIP-seq and DNase-seq, we found that developmentally inappropriate ASCL1 binding sites (that were unique to the overexpression context) had enrichment for the STAT binding motif. This study provides evidence that STAT pathway activation reduces the efficiency of ASCL1-mediated reprogramming in Muller glia, potentially by directing ASCL1 to inappropriate targets.
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stimulation of functional neuronal regeneration from muller glia in adult mice
Nature, 2017Co-Authors: Nikolas L. Jorstad, Matthew S Wilken, Fred Rieke, Leah S. Vandenbosch, Stefanie G. Wohl, William N Grimes, Takeshi Yoshimatsu, Rachel O L Wong, Thomas A RehAbstract:Many retinal diseases lead to the loss of retinal neurons and cause visual impairment. The adult mammalian retina has little capacity for regeneration. By contrast, teleost fish functionally regenerate their retina following injury, and Muller glia (MG) are the source of regenerated neurons. The proneural transcription factor ASCL1 is upregulated in MG after retinal damage in zebrafish and is necessary for regeneration. Although ASCL1 is not expressed in mammalian MG after injury, forced expression of ASCL1 in mouse MG induces a neurogenic state in vitro and in vivo after NMDA (N-methyl-d-aspartate) damage in young mice. However, by postnatal day 16, mouse MG lose neurogenic capacity, despite ASCL1 overexpression. Loss of neurogenic capacity in mature MG is accompanied by reduced chromatin accessibility, suggesting that epigenetic factors limit regeneration. Here we show that MG-specific overexpression of ASCL1, together with a histone deacetylase inhibitor, enables adult mice to generate neurons from MG after retinal injury. The MG-derived neurons express markers of inner retinal neurons, synapse with host retinal neurons, and respond to light. Using an assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq), we show that the histone deacetylase inhibitor promotes accessibility at key gene loci in the MG, and allows more effective reprogramming. Our results thus provide a new approach for the treatment of blinding retinal diseases.
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miR-124-9-9* potentiates ASCL1-induced reprogramming of cultured Müller glia.
Glia, 2016Co-Authors: Stefanie G. Wohl, Thomas A RehAbstract:The Muller glia of fish provide a source for neuronal regeneration after injury, but they do not do so in mammals. We previously showed that lentiviral gene transfer of the transcription factor Achaete-scute homolog 1 (ASCL1/Mash1) in murine Muller glia cultures resulted in partial reprogramming of the cells to retinal progenitors. The microRNAs (miRNAs) miR-124-9-9* facilitate neuronal reprogramming of fibroblasts, but their role in glia reprogramming has not been reported. The aim of this study was to test whether (1) lentiviral gene transfer of miR-124-9-9* can reprogram Muller glia into retinal neurons and (2) miR-124-9-9* can improve ASCL1-induced reprogramming. Primary Muller glia cultures were generated from postnatal day (P) 11/12 mice, transduced with lentiviral particles, i.e., miR-124-9-9*-RFP, nonsense-RFP, ASCL1-GFP, or GFP-control. Gene expression and immunofluorescence analyses were performed within 3 weeks after infection. 1. Overexpression of miR-124-9-9* induced the expression of the proneural factor ASCL1 and additional markers of neurons, including TUJ1 and MAP2. 2. When ASCL1 and miR-124-9-9* were combined, 50 to 60% of Muller glia underwent neuronal reprogramming, whereas ASCL1 alone results in a 30 to 35% reprogramming rate. 3. Analysis of the miR-124-9-9* treated glial cells showed a reduction in the level of Ctdsp1 and Ptbp1, indicating a critical role for the REST pathway in the repression of neuronal genes in Muller glia. Our data further suggest that miR-124-9-9* and the REST complex may play a role in regulating the reprogramming of Muller glia to progenitors that underlies retinal regeneration in zebrafish.
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transgenic expression of the proneural transcription factor ASCL1 in muller glia stimulates retinal regeneration in young mice
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Yumi Ueki, Masato Nakafuku, Matthew S Wilken, Kristen E Cox, Nikolas L. Jorstad, Laura Chipman, Kristen Sternhagen, Milesa Simic, Kristy Ullom, Thomas A RehAbstract:Muller glial cells are the source of retinal regeneration in fish and birds; although this process is efficient in fish, it is less so in birds and very limited in mammals. It has been proposed that factors necessary for providing neurogenic competence to Muller glia in fish and birds after retinal injury are not expressed in mammals. One such factor, the proneural transcription factor ASCL1, is necessary for retinal regeneration in fish but is not expressed after retinal damage in mice. We previously reported that forced expression of ASCL1 in vitro reprograms Muller glia to a neurogenic state. We now test whether forced expression of ASCL1 in mouse Muller glia in vivo stimulates their capacity for retinal regeneration. We find that transgenic expression of ASCL1 in adult Muller glia in undamaged retina does not overtly affect their phenotype; however, when the retina is damaged, the ASCL1-expressing glia initiate a response that resembles the early stages of retinal regeneration in zebrafish. The reaction to injury is even more pronounced in Muller glia in young mice, where the ASCL1-expressing Muller glia give rise to amacrine and bipolar cells and photoreceptors. DNaseI-seq analysis of the retina and Muller glia shows progressive reduction in accessibility of progenitor gene cis-regulatory regions consistent with the reduction in their reprogramming. These results show that at least one of the differences between mammal and fish Muller glia that bears on their difference in regenerative potential is the proneural transcription factor ASCL1.
Tou Yia Vue - One of the best experts on this subject based on the ideXlab platform.
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ASCL1 regulates neurodevelopmental transcription factors and cell cycle genes in brain tumors of glioma mouse models.
Glia, 2020Co-Authors: Tou Yia Vue, Mark D. Borromeo, Rahul K. Kollipara, Tomoyuki Mashimo, Tyler Smith, Robert Bachoo, Dennis K. Burns, Jane E. JohnsonAbstract:Glioblastomas (GBMs) are incurable brain tumors with a high degree of cellular heterogeneity and genetic mutations. Transcription factors that normally regulate neural progenitors and glial development are aberrantly coexpressed in GBM, conferring cancer stem-like properties to drive tumor progression and therapeutic resistance. However, the functional role of individual transcription factors in GBMs in vivo remains elusive. Here, we demonstrate that the basic-helix-loop-helix transcription factor ASCL1 regulates transcriptional targets that are central to GBM development, including neural stem cell and glial transcription factors, oncogenic signaling molecules, chromatin modifying genes, and cell cycle and mitotic genes. We also show that the loss of ASCL1 significantly reduces the proliferation of GBMs induced in the brain of a genetically relevant glioma mouse model, resulting in extended survival times. RNA-seq analysis of mouse GBM tumors reveal that the loss of ASCL1 is associated with downregulation of cell cycle genes, illustrating an important role for ASCL1 in controlling the proliferation of GBM.
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ASCL1 regulates proliferation of NG2-glia in the embryonic and adult spinal cord.
Glia, 2018Co-Authors: Demetra P. Kelenis, Jane E. Johnson, Emma Hart, Morgan Edwards-fligner, Tou Yia VueAbstract:NG2-glia are highly proliferative oligodendrocyte precursor cells (OPCs) that are widely distributed throughout the central nervous system (CNS). During development, NG2-glia predominantly differentiate into oligodendrocytes (OLs) to myelinate axon fibers, but they can also remain as OPCs persisting into the mature CNS. Interestingly, NG2-glia in the gray matter (GM) are intrinsically different from those in the white matter (WM) in terms of proliferation, differentiation, gene expression, and electrophysiological properties. Here we investigate the role of the transcriptional regulator, ASCL1, in controlling NG2-glia distribution and development in the GM and WM. In the spinal cord, ASCL1 levels are higher in WM NG2-glia than those in the GM. This differential level of ASCL1 in WM and GM NG2-glia is maintained into adult stages. Long-term clonal lineage analysis reveals that the progeny of single ASCL1+ oligodendrocyte progenitors (OLPs) and NG2-glia are primarily restricted to the GM or WM, even though they undergo extensive proliferation to give rise to large clusters of OLs in the postnatal spinal cord. Conditional deletion of ASCL1 specifically in NG2-glia in the embryonic or adult spinal cord resulted in a significant reduction in the proliferation but not differentiation of these cells. These findings illustrate that ASCL1 is an intrinsic regulator of the proliferative property of NG2-glia in the CNS.
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TMOD-12THE FUNCTION OF ACHAETE-SCUTE HOMOLOG 1 (ASCL1) IN GLIOBLASTOMA MULTIFORME
Neuro-Oncology, 2015Co-Authors: Tou Yia Vue, Mark D. Borromeo, Rahul K. Kollipara, Tomoyuki Mashimo, Tyler Smith, Robert Bachoo, Jane E. JohnsonAbstract:Glioblastoma multiforme (GBM) are incurable brain tumors that account for the majority of high-grade gliomas in the central nervous system (CNS). Currently, therapeutic approaches targeted at genomic alterations are ineffective in stopping these tumors and prognosis for GBM patients remains poor. Interestingly, many of the genes that are upregulated in GBM are transcription factors that are normally expressed in neural progenitor or stem cells. One such factor is the proneural factor Achaete-Scute Homolog 1(ASCL1), which plays a crucial role in cell fate specification, differentiation, and progenitor cell maintenance. It is possible that the aberrant expression of ASCL1 in GBM may bestowed upon tumor cells with “stem cell-like” property and the ability to develop resistance to chemotherapy and radiation. Indeed, ASCL1 has been shown to be required for the survival of a number of lung cancers with neuroendocrine features. Yet, to date the direct contribution and requirement of ASCL1 in GBM development in vivo remains unclear. In this study, we showed that ASCL1 is expressed in early stage as well as terminal stage brain tumors of a GBM mouse model. ChIP-seq shows that ASCL1 binds to about 9,800 sites within the genome associated with genes known to regulate diverse biological processes such as those involved in neural stem cell maintenance, inhibition of neural stem cell differentiation, and cellular response to vascular endothelial growth factor (VEGF). Conditional knock-out of ASCL1 (ASCL1-CKO) significantly improved the survival time of the GBM mouse model. Uniquely, RNA-seq gene expression profiling revealed that ASCL1+ tumors of the GBM mouse model closely resemble the proneural human GBM subtype, whereas ASCL1-CKO tumors resemble that of the mesenchymal GBM subtype. Collectively, these findings demonstrate a critical role for ASCL1, a single factor, in regulating GBM development and subtype, and may serve as a potential target for therapeutic purposes.
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ASCL1 controls the number and distribution of astrocytes and oligodendrocytes in the gray matter and white matter of the spinal cord
Development (Cambridge England), 2014Co-Authors: Tou Yia Vue, François Guillemot, Euiseok J. Kim, Carlos M. Parras, Jane E. JohnsonAbstract:Glia constitute the majority of cells in the mammalian central nervous system and are crucial for neurological function. However, there is an incomplete understanding of the molecular control of glial cell development. We find that the transcription factor ASCL1 (Mash1), which is best known for its role in neurogenesis, also functions in both astrocyte and oligodendrocyte lineages arising in the mouse spinal cord at late embryonic stages. Clonal fate mapping in vivo reveals heterogeneity in ASCL1-expressing glial progenitors and shows that ASCL1 defines cells that are restricted to either gray matter (GM) or white matter (WM) as astrocytes or oligodendrocytes. Conditional deletion of ASCL1 post-neurogenesis shows that ASCL1 is required during oligodendrogenesis for generating the correct numbers of WM but not GM oligodendrocyte precursor cells, whereas during astrocytogenesis ASCL1 functions in balancing the number of dorsal GM protoplasmic astrocytes with dorsal WM fibrous astrocytes. Thus, in addition to its function in neurogenesis, ASCL1 marks glial progenitors and controls the number and distribution of astrocytes and oligodendrocytes in the GM and WM of the spinal cord.
Mark D. Borromeo - One of the best experts on this subject based on the ideXlab platform.
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ASCL1 regulates neurodevelopmental transcription factors and cell cycle genes in brain tumors of glioma mouse models.
Glia, 2020Co-Authors: Tou Yia Vue, Mark D. Borromeo, Rahul K. Kollipara, Tomoyuki Mashimo, Tyler Smith, Robert Bachoo, Dennis K. Burns, Jane E. JohnsonAbstract:Glioblastomas (GBMs) are incurable brain tumors with a high degree of cellular heterogeneity and genetic mutations. Transcription factors that normally regulate neural progenitors and glial development are aberrantly coexpressed in GBM, conferring cancer stem-like properties to drive tumor progression and therapeutic resistance. However, the functional role of individual transcription factors in GBMs in vivo remains elusive. Here, we demonstrate that the basic-helix-loop-helix transcription factor ASCL1 regulates transcriptional targets that are central to GBM development, including neural stem cell and glial transcription factors, oncogenic signaling molecules, chromatin modifying genes, and cell cycle and mitotic genes. We also show that the loss of ASCL1 significantly reduces the proliferation of GBMs induced in the brain of a genetically relevant glioma mouse model, resulting in extended survival times. RNA-seq analysis of mouse GBM tumors reveal that the loss of ASCL1 is associated with downregulation of cell cycle genes, illustrating an important role for ASCL1 in controlling the proliferation of GBM.
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the epithelial sodium channel αenac is a downstream therapeutic target of ASCL1 in pulmonary neuroendocrine tumors
Translational Oncology, 2018Co-Authors: Min He, Mark D. Borromeo, Jane E. Johnson, Luc Girard, John D. Minna, Adi F. Gazdar, Sachith Gallolu Kankanamalage, Melanie H. CobbAbstract:Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma, designated as a recalcitrant cancer by the National Cancer Institute, in urgent need of new rational therapeutic targets. Previous studies have determined that the basic helix-loop-helix transcription factor achaete-scute homolog 1 (ASCL1) is essential for the survival and progression of a fraction of pulmonary neuroendocrine cancer cells, which include both SCLC and a subset of non-SCLC. Previously, to understand how ASCL1 initiates tumorigenesis in pulmonary neuroendocrine cancer and identify the transcriptional targets of ASCL1, whole-genome RNA-sequencing analysis combined with chromatin immunoprecipitation-sequencing was performed with a series of lung cancer cell lines. From this analysis, we discovered that the gene SCNN1A, which encodes the alpha subunit of the epithelial sodium channel (αENaC), is highly correlated with ASCL1 expression in SCLC. The product of the SCNN1A gene ENaC can be pharmacologically inhibited with amiloride, a drug that has been used clinically for close to 50 years. Amiloride inhibited growth of ASCL1-dependent SCLC more strongly than ASCL1-independent SCLC in vitro and slowed growth of ASCL1-driven SCLC in xenografts. We conclude that SCNN1A/αENaC is a direct transcriptional target of the neuroendocrine lung cancer lineage oncogene ASCL1 that can be pharmacologically targeted with antitumor effects.
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ASCL1 and NEUROD1 Reveal Heterogeneity in Pulmonary Neuroendocrine Tumors and Regulate Distinct Genetic Programs.
Cell reports, 2016Co-Authors: Mark D. Borromeo, Trisha K. Savage, Alexander Augustyn, Luc Girard, John D. Minna, Rahul K. Kollipara, Jihan K. Osborne, Adi F. Gazdar, Melanie H. CobbAbstract:Small cell lung carcinoma (SCLC) is a high-grade pulmonary neuroendocrine tumor. The transcription factors ASCL1 and NEUROD1 play crucial roles in promoting malignant behavior and survival of human SCLC cell lines. Here, we find that ASCL1 and NEUROD1 identify heterogeneity in SCLC, bind distinct genomic loci, and regulate mostly distinct genes. ASCL1, but not NEUROD1, is present in mouse pulmonary neuroendocrine cells, and only ASCL1 is required in vivo for tumor formation in mouse models of SCLC. ASCL1 targets oncogenic genes including MYCL1, RET, SOX2, and NFIB while NEUROD1 targets MYC. ASCL1 and NEUROD1 regulate different genes that commonly contribute to neuronal function. ASCL1 also regulates multiple genes in the NOTCH pathway including DLL3. Together, ASCL1 and NEUROD1 distinguish heterogeneity in SCLC with distinct genomic landscapes and distinct gene expression programs.
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TMOD-12THE FUNCTION OF ACHAETE-SCUTE HOMOLOG 1 (ASCL1) IN GLIOBLASTOMA MULTIFORME
Neuro-Oncology, 2015Co-Authors: Tou Yia Vue, Mark D. Borromeo, Rahul K. Kollipara, Tomoyuki Mashimo, Tyler Smith, Robert Bachoo, Jane E. JohnsonAbstract:Glioblastoma multiforme (GBM) are incurable brain tumors that account for the majority of high-grade gliomas in the central nervous system (CNS). Currently, therapeutic approaches targeted at genomic alterations are ineffective in stopping these tumors and prognosis for GBM patients remains poor. Interestingly, many of the genes that are upregulated in GBM are transcription factors that are normally expressed in neural progenitor or stem cells. One such factor is the proneural factor Achaete-Scute Homolog 1(ASCL1), which plays a crucial role in cell fate specification, differentiation, and progenitor cell maintenance. It is possible that the aberrant expression of ASCL1 in GBM may bestowed upon tumor cells with “stem cell-like” property and the ability to develop resistance to chemotherapy and radiation. Indeed, ASCL1 has been shown to be required for the survival of a number of lung cancers with neuroendocrine features. Yet, to date the direct contribution and requirement of ASCL1 in GBM development in vivo remains unclear. In this study, we showed that ASCL1 is expressed in early stage as well as terminal stage brain tumors of a GBM mouse model. ChIP-seq shows that ASCL1 binds to about 9,800 sites within the genome associated with genes known to regulate diverse biological processes such as those involved in neural stem cell maintenance, inhibition of neural stem cell differentiation, and cellular response to vascular endothelial growth factor (VEGF). Conditional knock-out of ASCL1 (ASCL1-CKO) significantly improved the survival time of the GBM mouse model. Uniquely, RNA-seq gene expression profiling revealed that ASCL1+ tumors of the GBM mouse model closely resemble the proneural human GBM subtype, whereas ASCL1-CKO tumors resemble that of the mesenchymal GBM subtype. Collectively, these findings demonstrate a critical role for ASCL1, a single factor, in regulating GBM development and subtype, and may serve as a potential target for therapeutic purposes.
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ASCL1 is a lineage oncogene providing therapeutic targets for high-grade neuroendocrine lung cancers
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Alexander Augustyn, Mark D. Borromeo, James P. Sullivan, Tao Wang, Chunli Shao, Patrick Dospoy, Junya Fujimoto, Victoria Lee, Christopher M. Tan, Jill E. LarsenAbstract:Aggressive neuroendocrine lung cancers, including small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), represent an understudied tumor subset that accounts for approximately 40,000 new lung cancer cases per year in the United States. No targeted therapy exists for these tumors. We determined that achaete-scute homolog 1 (ASCL1), a transcription factor required for proper development of pulmonary neuroendocrine cells, is essential for the survival of a majority of lung cancers (both SCLC and NSCLC) with neuroendocrine features. By combining whole-genome microarray expression analysis performed on lung cancer cell lines with ChIP-Seq data designed to identify conserved transcriptional targets of ASCL1, we discovered an ASCL1 target 72-gene expression signature that (i) identifies neuroendocrine differentiation in NSCLC cell lines, (ii) is predictive of poor prognosis in resected NSCLC specimens from three datasets, and (iii) represents novel “druggable” targets. Among these druggable targets is B-cell CLL/lymphoma 2, which when pharmacologically inhibited stops ASCL1-dependent tumor growth in vitro and in vivo and represents a proof-of-principle ASCL1 downstream target gene. Analysis of downstream targets of ASCL1 represents an important advance in the development of targeted therapy for the neuroendocrine class of lung cancers, providing a significant step forward in the understanding and therapeutic targeting of the molecular vulnerabilities of neuroendocrine lung cancer.
François Guillemot - One of the best experts on this subject based on the ideXlab platform.
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Id4 promotes the elimination of the pro-activation factor ASCL1 to maintain quiescence of adult hippocampal stem cells
eLife, 2019Co-Authors: Isabelle Blomfield, François Guillemot, Brenda Rocamonde, Maria Del Mar Masdeu, Eskeatnaf Mulugeta, Stefania Vaga, Debbie Van Den Berg, Emmanuelle Huillard, Noelia UrbánAbstract:Quiescence is essential for the long-term maintenance of adult stem cells but how stem cells maintain quiescence is poorly understood. Here, we show that neural stem cells (NSCs) in the adult mouse hippocampus actively transcribe the pro-activation factor ASCL1 regardless of their activated or quiescent states. We found that the inhibitor of DNA binding protein Id4 is enriched in quiescent NSCs and that elimination of Id4 results in abnormal accumulation of ASCL1 protein and premature stem cell activation. Accordingly, Id4 and other Id proteins promote elimination of ASCL1 protein in NSC cultures. Id4 sequesters ASCL1 heterodimerization partner E47, promoting ASCL1 protein degradation and stem cell quiescence. Our results highlight the importance of non-transcriptional mechanisms for the maintenance of NSC quiescence and reveal a role for Id4 as a quiescence-inducing factor, in contrast with its role of promoting the proliferation of embryonic neural progenitors.
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Id4 Eliminates the Pro-Activation Factor ASCL1 to Maintain Quiescence of Adult Hippocampal Stem Cells
SSRN Electronic Journal, 2018Co-Authors: Isabelle Blomfield, Debbie L. C. Van Den Berg, Brenda Rocamonde, Eskeatnaf Mulugeta, Stefania Vaga, Emmanuelle Huillard, Noelia Urbán, Maria Del Mar Masdeu, François GuillemotAbstract:SUMMARY Quiescence is essential for the long-term maintenance of adult stem cells and tissue homeostasis. However, how stem cells maintain quiescence is still poorly understood. Here we show that stem cells in the dentate gyrus of the adult hippocampus actively transcribe the pro-activation factor ASCL1 regardless of their activation state. We found that the inhibitor of DNA binding protein Id4 suppresses ASCL1 activity in neural stem cell cultures. Id4 sequesters ASCL1 heterodimerisation partner E47, promoting ASCL1 protein degradation and neural stem cell quiescence. Accordingly, elimination of Id4 from stem cells in the adult hippocampus results in abnormal accumulation of ASCL1 protein and premature stem cell activation. We also found that multiple signalling pathways converge on the regulation of Id4 to reduce the activity of hippocampal stem cells. Id4 therefore maintains quiescence of adult neural stem cells, in sharp contrast with its role of promoting the proliferation of embryonic neural progenitors.
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ASCL1 Is Required for the Development of Specific Neuronal Subtypes in the Enteric Nervous System.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2016Co-Authors: Fatima Memic, François Guillemot, Viktoria Knoflach, Rebecca Sadler, Gunilla Tegerstedt, Erik Sundström, Vassilis Pachnis, Ulrika MarklundAbstract:The enteric nervous system (ENS) is organized into neural circuits within the gastrointestinal wall where it controls the peristaltic movements, secretion, and blood flow. Although proper gut function relies on the complex neuronal composition of the ENS, little is known about the transcriptional networks that regulate the diversification into different classes of enteric neurons and glia during development. Here we redefine the role of ASCL1 (Mash1), one of the few regulatory transcription factors described during ENS development. We show that enteric glia and all enteric neuronal subtypes appear to be derived from ASCL1-expressing progenitor cells. In the gut of ASCL1 −/− mutant mice, neurogenesis is delayed and reduced, and posterior gliogenesis impaired. The ratio of neurons expressing Calbindin, TH, and VIP is selectively decreased while, for instance, 5-HT + neurons, which previously were believed to be ASCL1-dependent, are formed in normal numbers. Essentially the same differentiation defects are observed in ASCL1 KINgn2 transgenic mutants, where the proneural activity of Ngn2 replaces ASCL1, demonstrating that ASCL1 is required for the acquisition of specific enteric neuronal subtype features independent of its role in neurogenesis. In this study, we provide novel insights into the expression and function of ASCL1 in the differentiation process of specific neuronal subtypes during ENS development. SIGNIFICANCE STATEMENT The molecular mechanisms underlying the generation of different neuronal subtypes during development of the enteric nervous system are poorly understood despite its pivotal function in gut motility and involvement in gastrointestinal pathology. This report identifies novel roles for the transcription factor ASCL1 in enteric gliogenesis and neurogenesis. Moreover, independent of its proneurogenic activity, ASCL1 is required for the normal expression of specific enteric neuronal subtype characteristics. Distinct enteric neuronal subtypes are formed in a temporally defined order, and we observe that the early-born 5-HT + neurons are generated in ASCL1 −/− mutants, despite the delayed neurogenesis. Enteric nervous system progenitor cells may therefore possess strong intrinsic control over their specification at the initial waves of neurogenesis.
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ASCL1 controls the number and distribution of astrocytes and oligodendrocytes in the gray matter and white matter of the spinal cord
Development (Cambridge England), 2014Co-Authors: Tou Yia Vue, François Guillemot, Euiseok J. Kim, Carlos M. Parras, Jane E. JohnsonAbstract:Glia constitute the majority of cells in the mammalian central nervous system and are crucial for neurological function. However, there is an incomplete understanding of the molecular control of glial cell development. We find that the transcription factor ASCL1 (Mash1), which is best known for its role in neurogenesis, also functions in both astrocyte and oligodendrocyte lineages arising in the mouse spinal cord at late embryonic stages. Clonal fate mapping in vivo reveals heterogeneity in ASCL1-expressing glial progenitors and shows that ASCL1 defines cells that are restricted to either gray matter (GM) or white matter (WM) as astrocytes or oligodendrocytes. Conditional deletion of ASCL1 post-neurogenesis shows that ASCL1 is required during oligodendrogenesis for generating the correct numbers of WM but not GM oligodendrocyte precursor cells, whereas during astrocytogenesis ASCL1 functions in balancing the number of dorsal GM protoplasmic astrocytes with dorsal WM fibrous astrocytes. Thus, in addition to its function in neurogenesis, ASCL1 marks glial progenitors and controls the number and distribution of astrocytes and oligodendrocytes in the GM and WM of the spinal cord.
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FOXO3 shares common targets with ASCL1 genome-wide and inhibits ASCL1-dependent neurogenesis
Cell reports, 2013Co-Authors: Ashley E. Webb, Ben Martynoga, Noelia Urbán, Elizabeth A. Pollina, Thomas Vierbuchen, Duygu Ucar, Dena S. Leeman, Madhavi Sewak, Thomas A. Rando, François GuillemotAbstract:Summary FOXO transcription factors are central regulators of longevity from worms to humans. FOXO3, the FOXO isoform associated with exceptional human longevity, preserves adult neural stem cell pools. Here, we identify FOXO3 direct targets genome-wide in primary cultures of adult neural progenitor cells (NPCs). Interestingly, FOXO3-bound sites are enriched for motifs for bHLH transcription factors, and FOXO3 shares common targets with the proneuronal bHLH transcription factor ASCL1/MASH1 in NPCs. Analysis of the chromatin landscape reveals that FOXO3 and ASCL1 are particularly enriched at the enhancers of genes involved in neurogenic pathways. Intriguingly, FOXO3 inhibits ASCL1-dependent neurogenesis in NPCs and direct neuronal conversion in fibroblasts. FOXO3 also restrains neurogenesis in vivo. Our study identifies a genome-wide interaction between the prolongevity transcription factor FOXO3 and the cell-fate determinant ASCL1 and raises the possibility that FOXO3's ability to restrain ASCL1-dependent neurogenesis may help preserve the neural stem cell pool.
