Project description:We investigated the changes in the overall gene expression in MO3.13 cells induced by PLP1A243V and piracetam using RNA microarray analyses. We compared gene expression between PLP1WT and PLP1A243V and the expression profile in MO3.13 stably expressing PLP1A243V with/without piracetam.
Project description:Pelizaeus-Merzbacher disease (PMD) is a fatal X-linked disorder caused by loss of myelinating oligodendrocytes and consequent hypomyelination. The underlying cellular and molecular dysfunctions are not fully defined, but therapeutic enhancement of oligodendrocyte survival could restore functional myelination in patients. Here we generated pure, scalable quantities of iPSC-derived oligodendrocyte progenitor cells (OPCs) from a severe mouse model of PMD, Plp1jimpy. Temporal phenotypic and transcriptomic studies defined an early pathological window characterized by endoplasmic-reticulum (ER) stress and cell death as OPCs exit their progenitor state. High-throughput phenotypic screening identified a compound, Ro 25-6981, which modulates the ER stress response and rescues mutant oligodendrocyte survival in jimpy, in vitro and in vivo, and in human PMD oligocortical spheroids. Surprisingly, increasing oligodendrocyte survival did not restore subsequent myelination, revealing a second pathological phase. Collectively, our work shows that PMD oligodendrocyte loss can be rescued pharmacologically and defines a need for multifactorial intervention to restore myelination.
Project description:Pelizaeus-Merzbacher disease (PMD) is a fatal X-linked disorder caused by loss of myelinating oligodendrocytes and consequent hypomyelination. The underlying cellular and molecular dysfunctions are not fully defined, but therapeutic enhancement of oligodendrocyte survival could restore functional myelination in patients. Here we generated pure, scalable quantities of iPSC-derived oligodendrocyte progenitor cells (OPCs) from a severe mouse model of PMD, Plp1jimpy. Temporal phenotypic and transcriptomic studies defined an early pathological window characterized by endoplasmic-reticulum (ER) stress and cell death as OPCs exit their progenitor state. High-throughput phenotypic screening identified a compound, Ro 25-6981, which modulates the ER stress response and rescues mutant oligodendrocyte survival in jimpy, in vitro and in vivo, and in human PMD oligocortical spheroids. Surprisingly, increasing oligodendrocyte survival did not restore subsequent myelination, revealing a second pathological phase. Collectively, our work shows that PMD oligodendrocyte loss can be rescued pharmacologically and defines a need for multifactorial intervention to restore myelination.
Project description:Chemical Screening Identifies Enhancers of Mutant Oligodendrocyte Survival and Unmasks a Distinct Pathological Phase in Pelizaeus-Merzbacher Disease
Project description:Chemical Screening Identifies Enhancers of Mutant Oligodendrocyte Survival and Unmasks a Distinct Pathological Phase in Pelizaeus-Merzbacher Disease [RNA-seq]
Project description:Chemical Screening Identifies Enhancers of Mutant Oligodendrocyte Survival and Unmasks a Distinct Pathological Phase in Pelizaeus-Merzbacher Disease [scRNA-seq]
Project description:Pelizaeus-Merzbacher disease (PMD) is a severe hypomyelinating disease, characterized by ataxia, intellectual disability, epilepsy and premature death. In the majority of cases, PMD is caused by duplication of PLP1 that is expressed in myelinating oligodendrocytes. Despite detailed knowledge of PLP1, there is presently no curative therapy for PMD. We used a Plp1 transgenic PMD mouse model to test the therapeutic effect of Lonaprisan, an antagonist of the nuclear progesterone receptor, in lowering Plp1 mRNA overexpression. We applied placebo-controlled Lonaprisan therapy to PMD mice for 10 weeks and performed the grid slip analysis to assess the clinical phenotype. Additionally, mRNA expression and protein accumulation as well as histological analysis of the central nervous system were performed. While Plp1 mRNA levels are increased about 1.8-fold in PMD mice compared to wildtype controls, daily Lonaprisan treatment reduced overexpression at the RNA level up to 1.5-fold, which was sufficient to significantly improve a poor motor phenotype. Electron microscopy confirmed a 25% increase in the number of myelinated axons in the corticospinal tract when compared to untreated PMD mice. Microarray analysis revealed the upregulation of pro-apoptotic genes in PMD mice that could be partially rescued by Lonaprisan treatment, which also reduced microgliosis, astrogliosis, and lymphocyte infiltration. We treated mice with Lonaprisan or vehicle for 10 weeks. Brains from 13 week old mice were collected and subsequently lysed for total RNA extraction. We took three biological replicates for each Treatment and Placebo.
Project description:Pelizaeus-Merzbacher disease (PMD) is a severe hypomyelinating disease, characterized by ataxia, intellectual disability, epilepsy and premature death. In the majority of cases, PMD is caused by duplication of PLP1 that is expressed in myelinating oligodendrocytes. Despite detailed knowledge of PLP1, there is presently no curative therapy for PMD. We used a Plp1 transgenic PMD mouse model to test the therapeutic effect of Lonaprisan, an antagonist of the nuclear progesterone receptor, in lowering Plp1 mRNA overexpression. We applied placebo-controlled Lonaprisan therapy to PMD mice for 10 weeks and performed the grid slip analysis to assess the clinical phenotype. Additionally, mRNA expression and protein accumulation as well as histological analysis of the central nervous system were performed. While Plp1 mRNA levels are increased about 1.8-fold in PMD mice compared to wildtype controls, daily Lonaprisan treatment reduced overexpression at the RNA level up to 1.5-fold, which was sufficient to significantly improve a poor motor phenotype. Electron microscopy confirmed a 25% increase in the number of myelinated axons in the corticospinal tract when compared to untreated PMD mice. Microarray analysis revealed the upregulation of pro-apoptotic genes in PMD mice that could be partially rescued by Lonaprisan treatment, which also reduced microgliosis, astrogliosis, and lymphocyte infiltration.
Project description:The leukodystrophy Pelizaeus-Merzbacher disease (PMD) is caused by myelin protein proteolipid protein (PLP) gene mutations. PMD is characterized by oligodendrocyte death and CNS hypomyelination; thus, increasing oligodendrocyte survival and enhancing myelination could provide therapeutic benefit. We used the PMD mouse model Jimpy to explore the impact of the integrated stress response (ISR) on the oligodendrocyte response to mutant PLP expression. Jimpy animals in which the ISR-triggering eIF2 kinase PERK is inactivated have an extended lifespan that correlates with increased oligodendrocyte survival and enhanced CNS myelination. Inactivation of the downstream components of the ISR pathway CHOP and GADD34, in contrast, did not rescue oligodendrocytes or myelin. Phosphorylated eIF2 inhibits the exchange factor eIF2B, resulting in diminished protein synthesis. Treatment with small molecule eIF2B activators 2BAct and ISRIB dramatically increased oligodendrocyte survival, CNS myelination, and doubled the lifespan of Jimpy mice. These results suggest that ISR modulation could provide therapeutic benefit to PMD patients.
Project description:Pelizaeus-Merzbacher disease (PMD) is a pediatric disease of myelin in the central nervous system and manifests with a wide spectrum of clinical severities. Although PMD is a rare monogenic disease, hundreds of mutations in the X-linked myelin gene proteolipid protein 1 (PLP1) have been identified in humans. Attempts to identify a common pathogenic process underlying PMD have been complicated by an incomplete understanding of PLP1 dysfunction and limited access to primary human oligodendrocytes. To address this, we generated panels of human induced pluripotent stem cells (hiPSCs) and hiPSC-derived oligodendrocytes from 12 individuals with mutations spanning the genetic and clinical diversity of PMD—including point mutations and duplication, triplication, and deletion of PLP1—and developed an in vitro platform for molecular and cellular characterization of all 12 mutations simultaneously. We identified individual and shared defects in PLP1 mRNA expression and splicing, oligodendrocyte progenitor development, and oligodendrocyte morphology and capacity for myelination. These observations enabled classification of PMD subgroups by cell-intrinsic phenotypes and identified a subset of mutations for targeted testing of small-molecule modulators of the endoplasmic reticulum stress response, which improved both morphologic and myelination defects. Collectively, these data provide insights into the pathogeneses of a variety of PLP1 mutations and suggest that disparate etiologies of PMD could require specific treatment approaches for subsets of individuals. More broadly, this study demonstrates the versatility of a hiPSC-based panel spanning the mutational heterogeneity within a single disease and establishes a widely applicable platform for genotype-phenotype correlation and drug screening in any human myelin disorder.