Background Glioblastoma (GBM) stem-like cells (GSCs) are crucial drivers of treatment resistance ... more Background Glioblastoma (GBM) stem-like cells (GSCs) are crucial drivers of treatment resistance and tumor recurrence. While the concept of “migrating” cancer stem cells was proposed a decade ago, the roles and underlying mechanisms of the heterogeneous populations of GSCs remain poorly defined. Methods Cell migration using GBM cell lines and patient-derived GSCs was examined using Transwell inserts and the scratch assay. Single-cell RNA sequencing data analysis was used to map GSC drivers to specific GBM cell populations. Xenografted mice were used to model the role of brain-type fatty acid-binding protein (FABP7) in GBM infiltration and expansion. The mechanism by which FABP7 and its fatty acid ligands promote GSC migration was examined by gel-shift and luciferase gene reporter assays. Results A subpopulation of FABP7-expressing migratory GSCs was identified, with FABP7 upregulating SOX2, a key modulator for GBM stemness and plasticity, and ZEB1, a prominent factor in GBM epitheli...
Introduction: Neuroblastoma is a pediatric cancer originating from neural crest cells and is the ... more Introduction: Neuroblastoma is a pediatric cancer originating from neural crest cells and is the most lethal extracranial solid tumour in children. If the neuroblastoma is classified as “high-risk”, over 60% of children diagnosed do not survive past age five. High-risk neuroblastoma is often associated with amplification (increased copies) of the MYCN oncogene. DEAD box proteins are involved in modification of RNA secondary structure and are involved in cellular stress response. Previous research undertaken by the Godbout lab indicates that the DEAD Box 1 (DDX1) gene is co-amplified with the MYCN gene in about 50% of high-risk neuroblastomas, and it may be possible that amplification or knockdown of the DDX1 gene in neuroblastoma cell lines could improve their survival following treatment with DNA damaging agents (ionizing radiation and chemotherapy drugs). Hypothesis: Based on the lab’s prior knowledge of the role of DDX1, my hypothesis is that DDX1 knockdown will result in an improved cellular response to treatment, as DDX1 is known to play roles in cellular survival as well as in DNA double-strand break repair. Methods: Neuroblastoma resistance to treatment was measured indirectly using the soft agar colony formation assay. This assay selects for cancer cells and colony counts can be performed to determine the efficacy of treatment. I am examining the effect of DDX1 knockdown on rate of colony formation in DDX1-amplified and non-amplified cell lines, both prior to and one hour following treatment with ionizing radiation, and the chemotherapy drugs doxorubicin, vincristine, etoposide, bleomycin, and sodium arsenite. Results: Knockdown of DDX1 has opposite effects in DDX1-amplified and non-amplified cells. While knockdown of DDX1 decreases colony formation in DDX1-amplified cell lines, it results in increased colony formation in non-amplified cell lines. While knockdown of DDX1 had no effect on colony formation in cell lines treated with the microtubule-inhibiting chemotherapy drug vincristine, DDX1 knockdown resulted in an improved response to DNA-damaging chemotherapy drugs doxorubicin and etoposide in non-amplified cell lines. There is not yet sufficient data to determine the effect of DNA damaging agents on DDX1-amplified cell lines. Conclusion: Based on my results, DDX1 likely plays a role in the DNA damage response. At basal levels, DDX1 may repair DNA damage induced by ionizing radiation and chemotherapy agents, whereas when DDX1 is overexpressed or knocked down, it is no longer able to perform this function to the same level, thus decreasing neuroblastoma resistance to treatment. Altering the levels of DDX1 could potentially increase the efficacy of radiation and certain chemotherapy drugs in neuroblastoma treatment. leading to a reduction in the mortality of infants and children diagnosed with high-risk neuroblastoma.
International Journal of Developmental Neuroscience, Nov 25, 2008
Death-associated protein kinase (DAPK) is a Ca/calmodulinregulated serine/threonine kinase that a... more Death-associated protein kinase (DAPK) is a Ca/calmodulinregulated serine/threonine kinase that acts as a positive mediator of apoptosis in various death-signalling pathways. Increasing evidence indicate that the catalytic and expression of DAPK are also involved in neuronal death induced by cerebral ischemia and seizure. Previous works in our laboratory have shown that overexpression of DAPK is a component in glutamate-induced neuronal apoptosis cascade. Glutamate, the principal excitatory amino acid neurotransmitter in the central nervous system, is also a potential toxin leading to excitotoxicity that has been implicated in various neurological disorders ranging from acute insults such as stroke, hypoglycemia, trauma and epilepsy to chronic neurodegenerative states such as Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis and Alzheimer’s disease. In this study, we investigated whether the DAPK activity plays a role in glutamate-induced apoptosis in cultured cortical neurons. Cultured neurons exhibited a prevailing form of apoptosis in a delayed time course after treatment of glutamate, and a significant increase ofDAPK expression in neuronswas found. A peptide,with a composition identical to the last 17 8C-terminal amino acids (SCNSGTSYNSISSVVSR) of DAPK that inhibiting the pro-apoptotic functions of DAPK, was synthesized and internalized into cultured neurons. Neurons treated with the peptide were resistant to the apoptotic effects induced by glutamate treatment. In contrast, a peptidewith the sameaminoacid composition, butwhose sequence was scrambled, did not block glutamate-induced apoptosis. These results suggest that DAPK plays an important role in glutamateinducedneuronal apoptosis, and that blockingDAPKactivitymaybe as a potential therapeutic target for excitotoxicity.
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 2018
Malignant gliomas (MG) are highly invasive and aggressive brain tumors. Despite the current stand... more Malignant gliomas (MG) are highly invasive and aggressive brain tumors. Despite the current standard of care, the prognosis for patients with MG is abysmal– highlighting the need for novel, more effective treatment options to combat this aggressive disease. Oncolytic virus (OV) therapy is an advancing treatment option that harnesses tumor-selective viruses to kill cancer cells while simultaneously facilitating a systemic anti-tumor immune response. Many studies have noted synergistic effects when OV’s are combined with radiotherapy in preclinical cancer models, warranting further investigation of this multi-modal approach. Image-guided radiotherapy (IGRT) uses computer-modulated imaging techniques to precisely deliver ionizing radiation to treat cancer. Despite the precision IGRT offers, cancer cells can still be ‘missed’ due to tumor microextensions or radioresistant cell populations– such as glioma stem cells or therapy-induced senescent cancer cells –and may contribute to recurre...
The DEAD box protein DDX1, previously associated with 3’-end RNA processing and DNA repair, forms... more The DEAD box protein DDX1, previously associated with 3’-end RNA processing and DNA repair, forms large aggregates in the cytoplasm of early mouse embryos. Ddx1 knockout causes stalling of embryos at the 2-4 cell stages. Here, we identify a DDX1-containing membrane-bound calcium-containing organelle with a nucleic acid core. We show that aggregates of these organelles form ring-like structures in early-stage embryos which we have named Membrane Associated RNA-containing Vesicles. We present evidence that DDX1 is required for the formation of Membrane Associated RNA-containing Vesicles which in turn regulate the spatial distribution of calcium in embryos. We find that Ddx1 knockout in early embryos disrupts calcium distribution, and increases mitochondria membrane potential, mitochondrial activity, and reactive oxygen species. Sequencing analysis of embryos from Ddx1 heterozygote crosses reveals downregulation of a subset of RNAs involved in developmental and mitochondrial processes ...
Epithelial ovarian cancer (EOC) is a deadly q disease and the related statistics are alarming wit... more Epithelial ovarian cancer (EOC) is a deadly q disease and the related statistics are alarming with 15000 lives claimed in USA each year. EOC is a subtle disease since the majority of patients at presentation are diagnosed with a higher stage disease characterized by an aggressive potential. Early diagnosis seems to be of importance since complete cure can reach up to 90% if the disease is diagnosed at an early stage. Therefore, biological markers to detect patients at an early stage of the disease progression are urgently needed. In this study, the focus was centered on the transcription factor E2F5 used as biomarker and highly expressed at early stages of EOC pathogenesis. Therefore, we hypothesize that downstream genes regulated by this transcription factor might be also involved in the early events leading to ovarian cancer and can therefore potentially serve as useful biomarkers. Chromatin Immuno-Precipitation (ChIP) was performed using two ovarian cancer cell lines SK-OV-3 and ...
AP-2 is a family of transcription factors that play important roles during embryonic development.... more AP-2 is a family of transcription factors that play important roles during embryonic development. Two AP-2 genes, AP-2 � and AP-2�, have previously been characterized in chick retina. Here, we demonstrate that a third member of the chicken AP-2 family, AP-2�, is primarily expressed in the retina and brain, with highest levels at embryonic days 7 to 11. By in situ hybridization and immunohistochemical analysis, we show that AP-2 � RNA and protein are found in a subset of ganglion cells in embryonic chick retina. Coimmunostaining with anti-Brn3a and anti–AP-2 � antibodies indicates that approximately one-third of Brn3a-positive ganglion cells express AP-2�. AP-2 � RNA but not AP-2 � protein is also found in cells located in the outer half of the inner nuclear layer. The spatial and temporal distribution of AP-2 � protein in the retina suggests a transient role in a subset of late-born ganglion cells likely involving axonal trafficking or
Glioblastoma (GBM) is the most common primary brain malignancy. Brain fatty acid binding protein ... more Glioblastoma (GBM) is the most common primary brain malignancy. Brain fatty acid binding protein (B-FABP, FABP7) promotes glioblastoma (GBM) migration and correlates to dismal prognosis in GBM patients. Long chain polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA) and arachidonic acid (AA) are abundant in brain cell membranes. DHA and AA are preferred ligands of FABP7, with DHA having the stronger affinity for FABP7. Previous studies have shown that DHA inhibits GBM migration in an FABP7-dependent manner. In the current study, we have demonstrated that DHA dramatically altered membrane FABP7 nanoscale distribution pattern, which resulting from plasma membrane lipid ordered domain disruption in GBM cells and neurosphere cultures. We used quantitative membrane order assay to show that FABP7-expressing cells has increased membrane lipid order which is tightly correlated with higher GBM migration property. Using stimulated emission depletion (STED) microscopy, we obs...
The transcription of the mouse a-fetoprotein gene in the fetal liver, gut, and yolk sac is under ... more The transcription of the mouse a-fetoprotein gene in the fetal liver, gut, and yolk sac is under the control of at least four regulatory sequences, three 5' distal enhancers, and a proximal promoter region. In transgenic mice, the three enhancers exhibited distinct tissue preferences, with all three active in the visceral endoderm of the yolk sac, two in the fetal liver, and one in the fetal gut. To ask whether the enhancers are differentially utilized by the endogenous gene in the three tissues in vivo, we examined their differential sensitivity to the endonuclease DNase I. The experiments indicated that two of the three enhancers exhibited sensitivity to DNase I in all three fetal tissues, as well as in the adult liver, where the gene is transcriptionally repressed. The third enhancer, which exhibited the weakest activity in transgenic mice, was the least sensitive to DNase I in fetal liver and yolk sac and insensitive in the fetal gut. The major changes in the chromatin struc...
Glioblastoma (GBM) is an aggressive tumor with a dismal prognosis. Neural stem-like cells contrib... more Glioblastoma (GBM) is an aggressive tumor with a dismal prognosis. Neural stem-like cells contribute to GBM’s poor prognosis by driving drug resistance and maintaining cellular heterogeneity. GBM neural stem-like cells express high levels of brain fatty acid-binding protein (FABP7), which binds to polyunsaturated fatty acids (PUFAs) ω-6 arachidonic acid (AA) and ω-3 docosahexaenoic acid (DHA). Similar to brain, GBM tissue is enriched in AA and DHA. However, DHA levels are considerably lower in GBM tissue compared to adult brain. Therefore, it is possible that increasing DHA content in GBM, particularly in neural stem-like cells, might have therapeutic value. Here, we examine the fatty acid composition of patient-derived GBM neural stem-like cells grown as neurosphere cultures. We also investigate the effect of AA and DHA treatment on the fatty acid profiles of GBM neural stem-like cells with or without FABP7 knockdown. We show that DHA treatment increases DHA levels and the DHA:AA r...
ABSTRACTIn this study, we demonstrate that mouse DLX2 binds to the Olig2 gene locus in mouse embr... more ABSTRACTIn this study, we demonstrate that mouse DLX2 binds to the Olig2 gene locus in mouse embryonic forebrain in vivo. We further confirm the specificity and the transcriptional repressive effect of the binding in vitro. Furthermore, loss of Dlx1/2 function leads to increased Olig2 expression in the ventral embryonic mouse forebrain in vivo. As well, we demonstrate that chicken DLX1 binds to one chicken Olig2 gene domain in vitro, and overexpression of Dlx1 is sufficient to repress Olig2 expression in the developing chicken forebrain in ovo. Chicken DLX1 with a mutation eliminating its DNA binding ability is unable to bind to the Olig2 probe in vitro, and abrogates its repressive function on Olig2 expression in ovo. Our results establish that Dlx1/2 is both necessary and sufficient to repress oligodendrocyte specification mediated via direct transcriptional inhibition of Olig2 expression in the developing vertebrate forebrain.
FABP7 nanodomains on glioblastoma neural stem-like cell membranes are greatly reduced when cells ... more FABP7 nanodomains on glioblastoma neural stem-like cell membranes are greatly reduced when cells are cultured in medium supplemented with the omega-3 polyunsaturated fatty acid DHA. Glioblastoma cell migration is also reduced under these conditions.
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 2018
Introduction: Diffuse intrinsic pontine glioma (DIPG) is refractory to therapy. The identificatio... more Introduction: Diffuse intrinsic pontine glioma (DIPG) is refractory to therapy. The identification of histone H3.1/H3.3 K27M mutations in most DIPG has provided new insights. The DLX homeobox genes are expressed in the developing forebrain. The Dlx1/Dlx2 double knockout (DKO) mouse loses tangential GABAergic interneuron migration to the neocortex. We have identified genes that encode glutamic acid decarboxylase (GAD) enzymes as direct targets of DLX1/DLX2. In DIPG patients with H3.3 K27M mutations there is decreased Dlx2 and increased expression of the myelin transcription factor, Myt1. Methods and Results: We used bioinformatics approaches and chromatin immunoprecipitation (ChIP) assays to identify Olig2, Nkx2.2 and Myt1 promoter sequences as candidate DLX2 targets in vivo. DNA binding specificity was confirmed. The functional consequences of Dlx2 co-expression with reporter constructs of ChIP-isolated promoter fragments of Olig2 and Nkx2.2 demonstrated repression of gene targets i...
Background Glioblastoma (GBM) stem-like cells (GSCs) are crucial drivers of treatment resistance ... more Background Glioblastoma (GBM) stem-like cells (GSCs) are crucial drivers of treatment resistance and tumor recurrence. While the concept of “migrating” cancer stem cells was proposed a decade ago, the roles and underlying mechanisms of the heterogeneous populations of GSCs remain poorly defined. Methods Cell migration using GBM cell lines and patient-derived GSCs was examined using Transwell inserts and the scratch assay. Single-cell RNA sequencing data analysis was used to map GSC drivers to specific GBM cell populations. Xenografted mice were used to model the role of brain-type fatty acid-binding protein (FABP7) in GBM infiltration and expansion. The mechanism by which FABP7 and its fatty acid ligands promote GSC migration was examined by gel-shift and luciferase gene reporter assays. Results A subpopulation of FABP7-expressing migratory GSCs was identified, with FABP7 upregulating SOX2, a key modulator for GBM stemness and plasticity, and ZEB1, a prominent factor in GBM epitheli...
Introduction: Neuroblastoma is a pediatric cancer originating from neural crest cells and is the ... more Introduction: Neuroblastoma is a pediatric cancer originating from neural crest cells and is the most lethal extracranial solid tumour in children. If the neuroblastoma is classified as “high-risk”, over 60% of children diagnosed do not survive past age five. High-risk neuroblastoma is often associated with amplification (increased copies) of the MYCN oncogene. DEAD box proteins are involved in modification of RNA secondary structure and are involved in cellular stress response. Previous research undertaken by the Godbout lab indicates that the DEAD Box 1 (DDX1) gene is co-amplified with the MYCN gene in about 50% of high-risk neuroblastomas, and it may be possible that amplification or knockdown of the DDX1 gene in neuroblastoma cell lines could improve their survival following treatment with DNA damaging agents (ionizing radiation and chemotherapy drugs). Hypothesis: Based on the lab’s prior knowledge of the role of DDX1, my hypothesis is that DDX1 knockdown will result in an improved cellular response to treatment, as DDX1 is known to play roles in cellular survival as well as in DNA double-strand break repair. Methods: Neuroblastoma resistance to treatment was measured indirectly using the soft agar colony formation assay. This assay selects for cancer cells and colony counts can be performed to determine the efficacy of treatment. I am examining the effect of DDX1 knockdown on rate of colony formation in DDX1-amplified and non-amplified cell lines, both prior to and one hour following treatment with ionizing radiation, and the chemotherapy drugs doxorubicin, vincristine, etoposide, bleomycin, and sodium arsenite. Results: Knockdown of DDX1 has opposite effects in DDX1-amplified and non-amplified cells. While knockdown of DDX1 decreases colony formation in DDX1-amplified cell lines, it results in increased colony formation in non-amplified cell lines. While knockdown of DDX1 had no effect on colony formation in cell lines treated with the microtubule-inhibiting chemotherapy drug vincristine, DDX1 knockdown resulted in an improved response to DNA-damaging chemotherapy drugs doxorubicin and etoposide in non-amplified cell lines. There is not yet sufficient data to determine the effect of DNA damaging agents on DDX1-amplified cell lines. Conclusion: Based on my results, DDX1 likely plays a role in the DNA damage response. At basal levels, DDX1 may repair DNA damage induced by ionizing radiation and chemotherapy agents, whereas when DDX1 is overexpressed or knocked down, it is no longer able to perform this function to the same level, thus decreasing neuroblastoma resistance to treatment. Altering the levels of DDX1 could potentially increase the efficacy of radiation and certain chemotherapy drugs in neuroblastoma treatment. leading to a reduction in the mortality of infants and children diagnosed with high-risk neuroblastoma.
International Journal of Developmental Neuroscience, Nov 25, 2008
Death-associated protein kinase (DAPK) is a Ca/calmodulinregulated serine/threonine kinase that a... more Death-associated protein kinase (DAPK) is a Ca/calmodulinregulated serine/threonine kinase that acts as a positive mediator of apoptosis in various death-signalling pathways. Increasing evidence indicate that the catalytic and expression of DAPK are also involved in neuronal death induced by cerebral ischemia and seizure. Previous works in our laboratory have shown that overexpression of DAPK is a component in glutamate-induced neuronal apoptosis cascade. Glutamate, the principal excitatory amino acid neurotransmitter in the central nervous system, is also a potential toxin leading to excitotoxicity that has been implicated in various neurological disorders ranging from acute insults such as stroke, hypoglycemia, trauma and epilepsy to chronic neurodegenerative states such as Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis and Alzheimer’s disease. In this study, we investigated whether the DAPK activity plays a role in glutamate-induced apoptosis in cultured cortical neurons. Cultured neurons exhibited a prevailing form of apoptosis in a delayed time course after treatment of glutamate, and a significant increase ofDAPK expression in neuronswas found. A peptide,with a composition identical to the last 17 8C-terminal amino acids (SCNSGTSYNSISSVVSR) of DAPK that inhibiting the pro-apoptotic functions of DAPK, was synthesized and internalized into cultured neurons. Neurons treated with the peptide were resistant to the apoptotic effects induced by glutamate treatment. In contrast, a peptidewith the sameaminoacid composition, butwhose sequence was scrambled, did not block glutamate-induced apoptosis. These results suggest that DAPK plays an important role in glutamateinducedneuronal apoptosis, and that blockingDAPKactivitymaybe as a potential therapeutic target for excitotoxicity.
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 2018
Malignant gliomas (MG) are highly invasive and aggressive brain tumors. Despite the current stand... more Malignant gliomas (MG) are highly invasive and aggressive brain tumors. Despite the current standard of care, the prognosis for patients with MG is abysmal– highlighting the need for novel, more effective treatment options to combat this aggressive disease. Oncolytic virus (OV) therapy is an advancing treatment option that harnesses tumor-selective viruses to kill cancer cells while simultaneously facilitating a systemic anti-tumor immune response. Many studies have noted synergistic effects when OV’s are combined with radiotherapy in preclinical cancer models, warranting further investigation of this multi-modal approach. Image-guided radiotherapy (IGRT) uses computer-modulated imaging techniques to precisely deliver ionizing radiation to treat cancer. Despite the precision IGRT offers, cancer cells can still be ‘missed’ due to tumor microextensions or radioresistant cell populations– such as glioma stem cells or therapy-induced senescent cancer cells –and may contribute to recurre...
The DEAD box protein DDX1, previously associated with 3’-end RNA processing and DNA repair, forms... more The DEAD box protein DDX1, previously associated with 3’-end RNA processing and DNA repair, forms large aggregates in the cytoplasm of early mouse embryos. Ddx1 knockout causes stalling of embryos at the 2-4 cell stages. Here, we identify a DDX1-containing membrane-bound calcium-containing organelle with a nucleic acid core. We show that aggregates of these organelles form ring-like structures in early-stage embryos which we have named Membrane Associated RNA-containing Vesicles. We present evidence that DDX1 is required for the formation of Membrane Associated RNA-containing Vesicles which in turn regulate the spatial distribution of calcium in embryos. We find that Ddx1 knockout in early embryos disrupts calcium distribution, and increases mitochondria membrane potential, mitochondrial activity, and reactive oxygen species. Sequencing analysis of embryos from Ddx1 heterozygote crosses reveals downregulation of a subset of RNAs involved in developmental and mitochondrial processes ...
Epithelial ovarian cancer (EOC) is a deadly q disease and the related statistics are alarming wit... more Epithelial ovarian cancer (EOC) is a deadly q disease and the related statistics are alarming with 15000 lives claimed in USA each year. EOC is a subtle disease since the majority of patients at presentation are diagnosed with a higher stage disease characterized by an aggressive potential. Early diagnosis seems to be of importance since complete cure can reach up to 90% if the disease is diagnosed at an early stage. Therefore, biological markers to detect patients at an early stage of the disease progression are urgently needed. In this study, the focus was centered on the transcription factor E2F5 used as biomarker and highly expressed at early stages of EOC pathogenesis. Therefore, we hypothesize that downstream genes regulated by this transcription factor might be also involved in the early events leading to ovarian cancer and can therefore potentially serve as useful biomarkers. Chromatin Immuno-Precipitation (ChIP) was performed using two ovarian cancer cell lines SK-OV-3 and ...
AP-2 is a family of transcription factors that play important roles during embryonic development.... more AP-2 is a family of transcription factors that play important roles during embryonic development. Two AP-2 genes, AP-2 � and AP-2�, have previously been characterized in chick retina. Here, we demonstrate that a third member of the chicken AP-2 family, AP-2�, is primarily expressed in the retina and brain, with highest levels at embryonic days 7 to 11. By in situ hybridization and immunohistochemical analysis, we show that AP-2 � RNA and protein are found in a subset of ganglion cells in embryonic chick retina. Coimmunostaining with anti-Brn3a and anti–AP-2 � antibodies indicates that approximately one-third of Brn3a-positive ganglion cells express AP-2�. AP-2 � RNA but not AP-2 � protein is also found in cells located in the outer half of the inner nuclear layer. The spatial and temporal distribution of AP-2 � protein in the retina suggests a transient role in a subset of late-born ganglion cells likely involving axonal trafficking or
Glioblastoma (GBM) is the most common primary brain malignancy. Brain fatty acid binding protein ... more Glioblastoma (GBM) is the most common primary brain malignancy. Brain fatty acid binding protein (B-FABP, FABP7) promotes glioblastoma (GBM) migration and correlates to dismal prognosis in GBM patients. Long chain polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA) and arachidonic acid (AA) are abundant in brain cell membranes. DHA and AA are preferred ligands of FABP7, with DHA having the stronger affinity for FABP7. Previous studies have shown that DHA inhibits GBM migration in an FABP7-dependent manner. In the current study, we have demonstrated that DHA dramatically altered membrane FABP7 nanoscale distribution pattern, which resulting from plasma membrane lipid ordered domain disruption in GBM cells and neurosphere cultures. We used quantitative membrane order assay to show that FABP7-expressing cells has increased membrane lipid order which is tightly correlated with higher GBM migration property. Using stimulated emission depletion (STED) microscopy, we obs...
The transcription of the mouse a-fetoprotein gene in the fetal liver, gut, and yolk sac is under ... more The transcription of the mouse a-fetoprotein gene in the fetal liver, gut, and yolk sac is under the control of at least four regulatory sequences, three 5' distal enhancers, and a proximal promoter region. In transgenic mice, the three enhancers exhibited distinct tissue preferences, with all three active in the visceral endoderm of the yolk sac, two in the fetal liver, and one in the fetal gut. To ask whether the enhancers are differentially utilized by the endogenous gene in the three tissues in vivo, we examined their differential sensitivity to the endonuclease DNase I. The experiments indicated that two of the three enhancers exhibited sensitivity to DNase I in all three fetal tissues, as well as in the adult liver, where the gene is transcriptionally repressed. The third enhancer, which exhibited the weakest activity in transgenic mice, was the least sensitive to DNase I in fetal liver and yolk sac and insensitive in the fetal gut. The major changes in the chromatin struc...
Glioblastoma (GBM) is an aggressive tumor with a dismal prognosis. Neural stem-like cells contrib... more Glioblastoma (GBM) is an aggressive tumor with a dismal prognosis. Neural stem-like cells contribute to GBM’s poor prognosis by driving drug resistance and maintaining cellular heterogeneity. GBM neural stem-like cells express high levels of brain fatty acid-binding protein (FABP7), which binds to polyunsaturated fatty acids (PUFAs) ω-6 arachidonic acid (AA) and ω-3 docosahexaenoic acid (DHA). Similar to brain, GBM tissue is enriched in AA and DHA. However, DHA levels are considerably lower in GBM tissue compared to adult brain. Therefore, it is possible that increasing DHA content in GBM, particularly in neural stem-like cells, might have therapeutic value. Here, we examine the fatty acid composition of patient-derived GBM neural stem-like cells grown as neurosphere cultures. We also investigate the effect of AA and DHA treatment on the fatty acid profiles of GBM neural stem-like cells with or without FABP7 knockdown. We show that DHA treatment increases DHA levels and the DHA:AA r...
ABSTRACTIn this study, we demonstrate that mouse DLX2 binds to the Olig2 gene locus in mouse embr... more ABSTRACTIn this study, we demonstrate that mouse DLX2 binds to the Olig2 gene locus in mouse embryonic forebrain in vivo. We further confirm the specificity and the transcriptional repressive effect of the binding in vitro. Furthermore, loss of Dlx1/2 function leads to increased Olig2 expression in the ventral embryonic mouse forebrain in vivo. As well, we demonstrate that chicken DLX1 binds to one chicken Olig2 gene domain in vitro, and overexpression of Dlx1 is sufficient to repress Olig2 expression in the developing chicken forebrain in ovo. Chicken DLX1 with a mutation eliminating its DNA binding ability is unable to bind to the Olig2 probe in vitro, and abrogates its repressive function on Olig2 expression in ovo. Our results establish that Dlx1/2 is both necessary and sufficient to repress oligodendrocyte specification mediated via direct transcriptional inhibition of Olig2 expression in the developing vertebrate forebrain.
FABP7 nanodomains on glioblastoma neural stem-like cell membranes are greatly reduced when cells ... more FABP7 nanodomains on glioblastoma neural stem-like cell membranes are greatly reduced when cells are cultured in medium supplemented with the omega-3 polyunsaturated fatty acid DHA. Glioblastoma cell migration is also reduced under these conditions.
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques, 2018
Introduction: Diffuse intrinsic pontine glioma (DIPG) is refractory to therapy. The identificatio... more Introduction: Diffuse intrinsic pontine glioma (DIPG) is refractory to therapy. The identification of histone H3.1/H3.3 K27M mutations in most DIPG has provided new insights. The DLX homeobox genes are expressed in the developing forebrain. The Dlx1/Dlx2 double knockout (DKO) mouse loses tangential GABAergic interneuron migration to the neocortex. We have identified genes that encode glutamic acid decarboxylase (GAD) enzymes as direct targets of DLX1/DLX2. In DIPG patients with H3.3 K27M mutations there is decreased Dlx2 and increased expression of the myelin transcription factor, Myt1. Methods and Results: We used bioinformatics approaches and chromatin immunoprecipitation (ChIP) assays to identify Olig2, Nkx2.2 and Myt1 promoter sequences as candidate DLX2 targets in vivo. DNA binding specificity was confirmed. The functional consequences of Dlx2 co-expression with reporter constructs of ChIP-isolated promoter fragments of Olig2 and Nkx2.2 demonstrated repression of gene targets i...
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