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: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.
Project description:The goal of this study was to identify deregulated genes in Schwann cells of Pmp22 transgenic rats in comparison to wildtype rats. Three timepoints in the course of peripheral nerve myelination were chosen (embryonic day [E] 21, perinatal day [P]6 and P18) in order to reveal mechanistic insight into early pathological processes of Charcot-Marie-Tooth disease 1A (CMT1A).
Project description:Charcot-Marie-Tooth 1A is a demyelinating peripheral neuropathy caused by the duplication of peripheral myelin protein 22 (PMP22), which produces muscle weakness and loss of sensation in the hands and feet. A recent case-only genome wide association study by the Inherited Neuropathy Consortium identified a strong association between variants in signal induced proliferation associated 1 like 2 (SIPA1L2) and strength of foot dorsiflexion. To validate SIPA1L2 as a candidate modifier, and to assess its potential as a therapeutic target, we engineered mice with a deletion in SIPA1L2 and crossed them to the C3-PMP22 mouse model of CMT1A. We performed neuromuscular phenotyping and identified an interaction between Sipa1l2 deletion and muscular endurance decrements assayed by wire-hang duration in C3-PMP22 mice, as well as several interactions in femoral nerve axon morphometrics such as myelin thickness. Gene expression changes suggested an involvement of Sipa1l2 in cholesterol biosynthesis, which was also implicated in C3-PMP22 mice. Though several interactions between Sipa1l2 deletion and CMT1A-associated phenotypes were identified, validating a genetic interaction, the overall effect on neuropathy was small.
Project description:The transcription factor PAX6 is involved in the development of the eye and pancreatic islets, besides being associated with sleep-wake cycles. Here, we investigated a point mutation in the RED subdomain of PAX6, previously described in a human patient, to present a comprehensive study of a homozygous Pax6 mutation in the context of adult mammalian metabolism and circadian rhythm. Pax6Leca2 mice lack appropriate retinal structures for light perception and do not display normal daily rhythmic changes in energy metabolism. Despite β cell dysfunction and decreased insulin secretion, mutant mice have normal glucose tolerance. This is associated with reduced hepatic glucose production possibly due to altered circadian variation in expression of clock and metabolic genes, thereby evading hyperglycemia. Hence, our findings show that while the RED subdomain is important for β cell functional maturity, the Leca2 mutation impacts peripheral metabolism via loss of circadian rhythm, thus revealing pleiotropic effects of PAX6.