Project description:We compared gene expression at ages P4 and P60 in sciatic nerve of wild type mice and mice with peripheral neuropathies caused by altered Pmp22 gene dosage (homozygous knockout or transgene) or a point mutation (Trembler).
Project description:We compared gene expression at ages P4 and P60 in sciatic nerve of wild type mice and mice with peripheral neuropathies caused by altered Pmp22 gene dosage (homozygous knockout or transgene) or a point mutation (Trembler). Keywords: parallel sample
Project description:Peripheral myelin protein 22 (PMP22) is a tetraspan integral membrane protein for which mistrafficking-causing mutations are linked to the inherited peripheral neuropathy, Charcot-Marie-Tooth disease (CMTD). Wild type (WT) PMP22 is an inefficient folder with ~20% of the protein trafficking to the plasma membrane. We discovered that N-linked glycosylation significantly limits forward trafficking of WT and disease variants of PMP22. N-glycosylation of WT PMP22 was found to occur primarily post-translationally. Glycosylation inhibition dramatically increased PMP22 trafficking efficiency. Quantitative proteomics identified novel PMP22 interacting proteins that may impact trafficking. Our results suggest that critical quality control decisions for unstable L16P PMP22 occur at earlier stages in the trafficking pathway than for the WT protein. Knock-out cell lines of likely PMP22 interactors led to the discovery that calnexin limits trafficking of stable PMP22 variants, UGGT1 promotes trafficking and RER1 limits trafficking of all PMP22 variants. This work establishes N-glycosylation as a key determinant of PMP22 retention in the ER, ultimately limiting forward surface-trafficking.
Project description:Hereditary Motor and Sensory Neuropathies (HMSN) are the most common inherited peripheral neuropathies and comprise a group of genetically heterogeneous diseases. We study the genetic defects causing three demyelinating disorders: HMSN1A, HMSN-LOM and congenital cateracts facial dysmophism neuropathy (CCFDN) syndrome, which are caused by mutations in PMP22, NDRG1 and CTDP1, respectively. The function and patho-mechanisms of these genes is still unknown. To identify effects downstream of the mutations, thereby possibly involved in the disease process, we used Serial expression of gene expression (SAGE) and microarray analysis. We analyzed human Schwann cell lines from three normal subjects, one HMSN-LOM patient, two HMSN-1A patients and two CCFDN patients and compared our data to a recent dataset of human Schwann cells (4 normal subjects passage 1 vs. 3, GDS1869/GSE4030 M.B. Bunge, 2006). We excluded genes that were not consistently regulated between biological and technical replicates and genes that were found to be influenced by passage number (p<0.05). Comparing expression profiles of demyelinating neuropathies with different mutations we identified: 1. expression signatures specific for each genotype. 2. Genes commonly (dys)regulated in all screened neuropathies. Interestingly, these include genes that play a role in reorganization of sodium channels in central and peripheral nerves (S100A10, CD90), or extracellular matrix remodeling (e.g. TGFBI, SERPINE1, THBS1). We also found high up-regulation of genes involved in Schwann cell lineage and in particular, genes that are associated with an immature or pre-myelinating Schwann cell phenotype (i.e. Sox2, Sox10, COL18A1, TFAP2A, Pax3, CDH19). Our study shows that many genes, possibly contributing to nerve pathology can be identified by this approach. Experiment Overall Design: Experimental design: in total 12 (two-color) arrays were run. All neuropathy samples were in duplicate (technical replicates). Two CCFDN and two HMSN1A patients were also analyzed as biological replicates. Three healthy subjects were included from which one was in duplicate. All samples (Cy3) were compared to a common reference pool (Cy5) which consisted of a mix of all samples.
Project description:Hereditary Motor and Sensory Neuropathies (HMSN) are the most common inherited peripheral neuropathies and comprise a group of genetically heterogeneous diseases. We study the genetic defects causing three demyelinating disorders: HMSN1A, HMSN-LOM and congenital cateracts facial dysmophism neuropathy (CCFDN) syndrome, which are caused by mutations in PMP22, NDRG1 and CTDP1, respectively. The function and patho-mechanisms of these genes is still unknown. To identify effects downstream of the mutations, thereby possibly involved in the disease process, we used Serial expression of gene expression (SAGE) and microarray analysis. We analyzed human Schwann cell lines from three normal subjects, one HMSN-LOM patient, two HMSN-1A patients and two CCFDN patients and compared our data to a recent dataset of human Schwann cells (4 normal subjects passage 1 vs. 3, GDS1869/GSE4030 M.B. Bunge, 2006). We excluded genes that were not consistently regulated between biological and technical replicates and genes that were found to be influenced by passage number (p<0.05). Comparing expression profiles of demyelinating neuropathies with different mutations we identified: 1. expression signatures specific for each genotype. 2. Genes commonly (dys)regulated in all screened neuropathies. Interestingly, these include genes that play a role in reorganization of sodium channels in central and peripheral nerves (S100A10, CD90), or extracellular matrix remodeling (e.g. TGFBI, SERPINE1, THBS1). We also found high up-regulation of genes involved in Schwann cell lineage and in particular, genes that are associated with an immature or pre-myelinating Schwann cell phenotype (i.e. Sox2, Sox10, COL18A1, TFAP2A, Pax3, CDH19). Our study shows that many genes, possibly contributing to nerve pathology can be identified by this approach. Keywords: disease state analysis, genotype down-stream effects analysis
Project description:Neurofibromatosis type 1 (NF1) patients are predisposed to develop neurofibromas but the underlying molecular mechanism(s) of neurofibromagenesis are not fully understood. We showed that dual genetic deletion of Runx1 (Rx1) and Runx3 (Rx3) in Schwann cells (SCs) and Schwann cell precursors (SCPs) significantly delayed neurofibromagenesis and prolonged mouse survival. We identified peripheral myelin protein 22 (Pmp22/Gas3) related to tumor initiation. Knockdown of Pmp22 with shRNAs increased Rx1fl/fl;Rx3fl/fl;Nf1fl/fl;DhhCre sphere numbers and enabled significantly more neurofibroma like micro-lesions on transplantation. Conversely, overexpression of Pmp22 in mouse neurofibroma SCs decreased proliferation. Mechanistically, Rx1/3 regulated alterative Pmp22 promoter usage and reduced post transcriptional expression of Pmp22. Finally, pharmacological inhibition of Runx/core binding factor beta (Cbf-β) activity significantly reduced neurofibroma volume in vivo. Thus, we identified a novel signaling pathway involving Rx1/3 suppression of Pmp22 in neurofibroma initiation and/or maintenance. Targeting disruption of Runx/Cbf-β interaction might provide a novel therapy for neurofibroma patients.
Project description:Neurofibromatosis type 1 (NF1) patients are predisposed to develop neurofibromas but the underlying molecular mechanism(s) of neurofibromagenesis are not fully understood. We showed that dual genetic deletion of Runx1 (Rx1) and Runx3 (Rx3) in Schwann cells (SCs) and Schwann cell precursors (SCPs) significantly delayed neurofibromagenesis and prolonged mouse survival. We identified peripheral myelin protein 22 (Pmp22/Gas3) related to tumor initiation. Knockdown of Pmp22 with shRNAs increased Rx1fl/fl;Rx3fl/fl;Nf1fl/fl;DhhCre sphere numbers and enabled significantly more neurofibroma like micro-lesions on transplantation. Conversely, overexpression of Pmp22 in mouse neurofibroma SCs decreased proliferation. Mechanistically, Rx1/3 regulated alterative Pmp22 promoter usage and reduced post transcriptional expression of Pmp22. Finally, pharmacological inhibition of Runx/core binding factor beta (Cbf-β) activity significantly reduced neurofibroma volume in vivo. Thus, we identified a novel signaling pathway involving Rx1/3 suppression of Pmp22 in neurofibroma initiation and/or maintenance. Targeting disruption of Runx/Cbf-β interaction might provide a novel therapy for neurofibroma patients.
Project description:Neurofibromatosis type 1 (NF1) patients are predisposed to develop neurofibromas but the underlying molecular mechanism(s) of neurofibromagenesis are not fully understood. We showed that dual genetic deletion of Runx1 (Rx1) and Runx3 (Rx3) in Schwann cells (SCs) and Schwann cell precursors (SCPs) significantly delayed neurofibromagenesis and prolonged mouse survival. We identified peripheral myelin protein 22 (Pmp22/Gas3) related to tumor initiation. Knockdown of Pmp22 with shRNAs increased Rx1fl/fl;Rx3fl/fl;Nf1fl/fl;DhhCre sphere numbers and enabled significantly more neurofibroma like micro-lesions on transplantation. Conversely, overexpression of Pmp22 in mouse neurofibroma SCs decreased proliferation. Mechanistically, Rx1/3 regulated alterative Pmp22 promoter usage and reduced post transcriptional expression of Pmp22. Finally, pharmacological inhibition of Runx/core binding factor beta (Cbf-β) activity significantly reduced neurofibroma volume in vivo. Thus, we identified a novel signaling pathway involving Rx1/3 suppression of Pmp22 in neurofibroma initiation and/or maintenance. Targeting disruption of Runx/Cbf-β interaction might provide a novel therapy for neurofibroma patients.
Project description:Neurofibromatosis type 1 (NF1) patients are predisposed to develop neurofibromas but the underlying molecular mechanism(s) of neurofibromagenesis are not fully understood. We showed that dual genetic deletion of Runx1 (Rx1) and Runx3 (Rx3) in Schwann cells (SCs) and Schwann cell precursors (SCPs) significantly delayed neurofibromagenesis and prolonged mouse survival. We identified peripheral myelin protein 22 (Pmp22/Gas3) related to tumor initiation. Knockdown of Pmp22 with shRNAs increased Rx1fl/fl;Rx3fl/fl;Nf1fl/fl;DhhCre sphere numbers and enabled significantly more neurofibroma like micro-lesions on transplantation. Conversely, overexpression of Pmp22 in mouse neurofibroma SCs decreased proliferation. Mechanistically, Rx1/3 regulated alterative Pmp22 promoter usage and reduced post transcriptional expression of Pmp22. Finally, pharmacological inhibition of Runx/core binding factor beta (Cbf-β) activity significantly reduced neurofibroma volume in vivo. Thus, we identified a novel signaling pathway involving Rx1/3 suppression of Pmp22 in neurofibroma initiation and/or maintenance. Targeting disruption of Runx/Cbf-β interaction might provide a novel therapy for neurofibroma patients.