Project description:Adult oligodendrocyte progenitors (aOPCs) share with their neonatal counterpart (nOPC) the ability to give rise to myelinating oligodendrocytes, but they also display unique functional features. This study addresses the molecular mechanisms underlying the intrinsic differences between these two populations. Using RNA-sequencing and unbiased histone proteomics analysis, we define the unique transcriptome and histone marks of aOPCs. We used an unbiased histone proteomic approach to ask whether differences in post-translational modifications of nucleosomal histones may underlie the distinct transcriptome of nOPCs and aOPCs. Using Pdgfra-H2BEGFP reporter mice, we sorted for the nuclei of nOPCs and aOPCs, extracted their histones and then conducted a proteomic analysis, which identified several histone modifications of lysine residues in the tails of histones H3 and H4.
Project description:Adult oligodendrocyte progenitors (aOPCs) share with their neonatal counterpart (nOPCs) the ability to give rise to myelinating oligodendrocytes, but they also display unique functional features. This study addresses the molecular mechanisms underlying the intrinsic differences between these two populations. Using RNA-sequencing and unbiased histone proteomics analysis, we define the unique transcriptome and histone marks of aOPCs. We describe the lower proliferative capacity and higher levels of expression of oligodendrocyte specific genes in aOPC compared to nOPC. We also identify greater levels of activating H4K8ac histone marks in aOPCs compared to nOPCs, and increased occupancy of this mark at chromatin locations corresponding to oligodendrocyte-specific transcription factors and lipid metabolism genes. Pharmacological inhibition of H4K8ac deposition reduces the levels of these transcripts in aOPCs, rendering their transcriptome more similar to nOPCs. The repressive H4K20me3 mark is also higher in aOPCs compared to nOPCs and pharmacological inhibition of its deposition results in increased levels of genes related to the mature oligodendrocyte state. Overall, this study identifies two histone marks which are important for the unique transcriptional identity of aOPCs.
Project description:This study provides an overview of the transcriptional signature of oligodendrocyte progenitor cells (OPCs) exposed to the CSF collected from multiple sclerosis patients with either a relapsing remitting disease course (RRMS) or a confirmed primary progressive diagnosis (PPMS). Using an Affymetrix microarray we were able to detect a set of common and unique genes for each treatment group. Gene ontology analysis revealed a common group of genes involved in protein transport, actin dynamics and response to stress and DNA damage, while the RRMS-specific genes were grouped according to protein complex biogenesis, nuclear transport and RNA processing. The transcriptional signature of progenitors exposed to PPMS was characterized by an up-regulation of the pro-differentiation adhesion molecule Lgals3. We confirmed increased protein levels of its gene product,product; galectin-3 in proliferating OPCs incubated with CSF from PPMS patients and also found a four-fold increase in mRNA transcript levels of galectin-3 in human post-mortem normal-appearing white matter samples of primary progressive MS patients when compared to non-neurological controls. This study will help to better understand the common and specific transcriptional changes induced in the different subtypes of MS and therefore find more specific molecular targets for each disease subtype. Comparison of transcriptional signature by microarray analysis of OPCs treated with RRMS and PPMS CSF.
Project description:Glial progenitor cells (GPCs) pervade the human brain. These cells express gangliosides recognized by MAb A2B5, and some but not all can generate oligodendrocytes. Since some A2B5+ GPCs express PDGFa receptor (PDGFRa), which is critical to oligodendrocyte development, we asked if PDGFRa-directed sorting might isolate oligodendrocyte-competent progenitors. We used FACS to sort PDGFRa+ cells from the second trimester fetal human forebrain, based on expression of the PDGFRa epitope CD140a. CD140a+ cells could be maintained as mitotic progenitors that could be instructed to either oligodendrocyte or astrocyte phenotype. Transplanted CD140a+ cells robustly myelinated the hypomyelinated shiverer mouse brain. Microarray confirmed that CD140a+ cells differentially expressed PDGFRA, NG2, OLIG1/2, NKX2.2 and SOX2. Some expressed CD9, thereby defining a CD140a+/CD9+ fraction of oligodendrocyte-biased progenitors. CD140a+ cells differentially expressed genes of the PTN-PTPRZ1, wnt, notch and BMP pathways, suggesting the interaction of self-renewal and fate-restricting pathways in these cells, while identifying targets for their mobilization and instruction.
Project description:This study provides an overview of the transcriptional signature of oligodendrocyte progenitor cells (OPCs) exposed to the CSF collected from multiple sclerosis patients with either a relapsing remitting disease course (RRMS) or a confirmed primary progressive diagnosis (PPMS). Using an Affymetrix microarray we were able to detect a set of common and unique genes for each treatment group. Gene ontology analysis revealed a common group of genes involved in protein transport, actin dynamics and response to stress and DNA damage, while the RRMS-specific genes were grouped according to protein complex biogenesis, nuclear transport and RNA processing. The transcriptional signature of progenitors exposed to PPMS was characterized by an up-regulation of the pro-differentiation adhesion molecule Lgals3. We confirmed increased protein levels of its gene product,product; galectin-3 in proliferating OPCs incubated with CSF from PPMS patients and also found a four-fold increase in mRNA transcript levels of galectin-3 in human post-mortem normal-appearing white matter samples of primary progressive MS patients when compared to non-neurological controls. This study will help to better understand the common and specific transcriptional changes induced in the different subtypes of MS and therefore find more specific molecular targets for each disease subtype.
Project description:Adult oligodendrocyte progenitors (aOPCs) share with their neonatal counterpart (nOPC) the ability to give rise to myelinating oligodendrocytes, but they also display unique functional features. This study addresses the molecular mechanisms underlying the intrinsic differences between these two populations. Using RNA-sequencing and unbiased histone proteomics analysis performed on PDGFRa+ OPCs sorted from a reporter mouse, we define the unique transcriptome and histone marks of aOPCs. We describe the higher levels of genes related to lipid metabolism and myelin sheath, and lower expression of genes related to cycle and proliferation in aOPCs compared to nOPCs. We also identify greater levels of activating H4K8ac and repressive H4K20me3 histone marks in aOPCs compared to nOPCs, and increased occupancy of H4K8ac mark at chromatin locations corresponding to oligodendrocyte-specific genes. Pharmacological inhibition of histone acetylation in neonatal O4+OPCs (nO4+OPCs) and adult O4+OPCs (aO4+OPCs) followed by RNA-sequencing showed a moderate change in the transcriptome of these cells resulting in the decrease of proliferation capacity in aO4+OPCs but not nO4+OPCs. Pharmacological inhibition of H4K20me3 mark was not sufficient to change the transcriptome or functional properties of nO4+OPCs and aO4+OPC. Overall, this study identifies histone acetylation as key in regulating the proliferation of aO4+OPCs.