Cell autonomous requirement of Neurofibrimin (Nf1) for postnatal muscle hypertrophic growth and metabolic homeostasis
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ABSTRACT: Our results demonstrate a cell-autonomous role for Nf1 in myogenic cells during postnatal muscle growth required for metabolic and proteostatic homeostasis.
Project description:Background Neurofibromatosis type 1 (NF1) is a multi-organ disease caused by mutations in Neurofibromin (NF1). Amongst other features, NF1 patients frequently show reduced muscle mass and strength, impairing patients’ mobility and increasing the risk of fall. The role of Nf1 in muscle and the cause for the NF1-associated myopathy is mostly unknown. Methods To dissect the function of Nf1 in muscle, we created muscle-specific knockout mouse models for Nf1, inactivating Nf1 in the prenatal myogenic lineage either under the Lbx1 promoter or under the Myf5 promoter. Mice were analyzed during pre-and postnatal myogenesis and muscle growth. Results Nf1Lbx1 and Nf1Myf5 animals showed only mild defects in prenatal myogenesis. Nf1Lbx1 animals were perinatally lethal, while Nf1Myf5 animals survived up to approx. 25 weeks. Nf1Myf5 animals showed decreased postnatal growth, reduced muscle size, and fast fiber atrophy. Proteome and transcriptome analysis of muscle tissue indicated decreased protein synthesis and increased proteasomal degradation, and decreased glycolytic and increased oxidative activity in muscle tissue. Real-time respirometry demonstrated enhanced oxidative metabolism in Nf1Myf5 muscles concomitant to a fiber type shift from type 2B to type 2A and type 1. Nf1Myf5 muscles showed hallmarks of mild oxidative stress and increased activation of AMPK indicating an energy deficit, increased expression of atrogenes and decreased activation of mTORC1. Proteome and transcriptome analysis indicated that oxidative fibers mainly relied on fatty acid catabolism. Inline, Nf1Myf5 animals showed a drastic reduction of white, but not brown, adipose tissue. Conclusions Our results demonstrate a cell-autonomous role for Nf1 in myogenic cells during postnatal muscle growth required for metabolic and proteostatic homeostasis. Furthermore, Nf1 deficiency in muscle leads to cross-tissue communication and mobilization of lipid reserves.
Project description:BackgroundNeurofibromatosis type 1 (NF1) is a multi-organ disease caused by mutations in neurofibromin 1 (NF1). Amongst other features, NF1 patients frequently show reduced muscle mass and strength, impairing patients' mobility and increasing the risk of fall. The role of Nf1 in muscle and the cause for the NF1-associated myopathy are mostly unknown.MethodsTo dissect the function of Nf1 in muscle, we created muscle-specific knockout mouse models for NF1, inactivating Nf1 in the prenatal myogenic lineage either under the Lbx1 promoter or under the Myf5 promoter. Mice were analysed during prenatal and postnatal myogenesis and muscle growth.ResultsNf1Lbx1 and Nf1Myf5 animals showed only mild defects in prenatal myogenesis. Nf1Lbx1 animals were perinatally lethal, while Nf1Myf5 animals survived only up to approximately 25 weeks. A comprehensive phenotypic characterization of Nf1Myf5 animals showed decreased postnatal growth, reduced muscle size, and fast fibre atrophy. Proteome and transcriptome analyses of muscle tissue indicated decreased protein synthesis and increased proteasomal degradation, and decreased glycolytic and increased oxidative activity in muscle tissue. High-resolution respirometry confirmed enhanced oxidative metabolism in Nf1Myf5 muscles, which was concomitant to a fibre type shift from type 2B to type 2A and type 1. Moreover, Nf1Myf5 muscles showed hallmarks of decreased activation of mTORC1 and increased expression of atrogenes. Remarkably, loss of Nf1 promoted a robust activation of AMPK with a gene expression profile indicative of increased fatty acid catabolism. Additionally, we observed a strong induction of genes encoding catabolic cytokines in muscle Nf1Myf5 animals, in line with a drastic reduction of white, but not brown adipose tissue.ConclusionsOur results demonstrate a cell autonomous role for Nf1 in myogenic cells during postnatal muscle growth required for metabolic and proteostatic homeostasis. Furthermore, Nf1 deficiency in muscle drives cross-tissue communication and mobilization of lipid reserves.
Project description:Purpose: To study Nf1 regulated pathways in controlling juvenile satellite cells quiescence induction. Methods: We sequenced total mRNAs isolated from juvenile satellite cells FACS sorted from postnatal day 7 Control (Nf1flox/+ Myf5Cre+) and KO (Nf1flox/flox Myf5Cre+) mouse hindlimb skeletal muscle. Results: Our study suggests that Nf1 is required for maintaining the balance between quiescence induction and amplification / differentiation in the postnatal MP pool. Conclusions: The tumor suppressor Nf1 maintains the myogenic progenitor (MP) pool during postnatal muscle development.
Project description:One of the major primary features of the neurocutaneous genetic disorder Neurofibromatosis type 1 are the hyperpigmentary café-au-lait macules where dysregulation of melanocyte development, proliferation and differentiation is considered to play a key etiopathogenic role. To gain better insight in the possible role of the tumor suppressor gene NF1, a transcriptomic microarray analysis was performed on human NF1 heterozygous (NF1+/-) melanocytes of a Neurofibromatosis type 1 patient and NF1 wild type (NF1+/+) melanocytes of a healthy control patient, both cultured from normally pigmented and hyperpigmented lesional café-au-lait skin. Out of 13,850 unique genes, a total of 137 had a significant twofold or more up- (72) or down-regulated (65) expression in NF1+/- melanocytes compared to NF1+/+ melanocytes (genotype effect). Considering possible intrinsic genetic variation in lesional skin, melanocytes showed a total of 51 genes having a significant twofold or more up- (37) or down-regulated (14) expression when they were cultured from hyperpigmentary café-au-lait skin compared to normally pigmented skin (lesional skin type effect). NF1+/- café-au-lait skin melanocytes showed 468 genes with a significant two-fold or more up- (183) or down-regulated (285) expression going beyond the sum of the separate main effects (interaction). Detailed analysis enabled the identification of several modulated genes in NF1+/- (café-au-lait skin) melanocytes, mainly involved in controlling cell proliferation and cell maintenance, in cell adhesion and, surprisingly, in the immune response. An interesting finding was that a high number of transcription factor genes were differentially modulated, among which a specific subset - important in melanocyte-lineage development - showed downregulation in a transcriptional cis-regulatory network governing the activation of the melanocyte-specific dopachrome tautomerase (DCT) gene.
Project description:Analysis of the effect of NF1 second hit mutation to the reading of the whole human genome by comparing the gene expression profiles of neurofibroma derived Schwann cell cultures representing two different NF1 genotypes (NF1+/- and NF1-/-).
Project description:Schwann cells and macrophages were dissociated from normal DRGs and 1- and 7-month-old neurofibroma. Schwann cells from neurofibroma have Nf1-/- phenotypes. All macrophages have Nf1+/+ phenotypes. We used microarrays (Affymetrix MoGene 2.0 ST GeneChip) to detect transcriptomal changes between 7-month-old neurofibroma Schwann cells (or macrophages) versus 1-month-old wild-type (or neurofibroma) Schwann cells (or macrophages). Expression data of three sets of cells: (1)Schwann cells and macrophages from 1-month-old wild-type mouse dorsal root ganglia, (2) Schwann cells (Nf1-/-) and macrophages (Nf1+/+) from 1-month-old neurofibroma, (3) Schwann cells (Nf1-/-) and macrophages (Nf1+/+) from 7-month-old neurofibroma We chopped mouse DRG/neurofibromas into 1-3 mm^3 pieces and plated them in dissociation medium containing 20mL L-15 (Mediatech), 0.5 mg/mL collagenase type 1 (Worthington; Lakewood, NJ), and 2.5 mg/mL dispase protease type II (Cambrex; East Rutherford, NJ) at 37°C for 4-6 hours with shaking. The dissociation reaction was stopped by adding DMEM +10%FBS. Undigested DRG/tumors were excluded by 100µM cell strainer. Cells were collected by centrifugation. For each microarrays (Schwann cell, macrophage), Affymetrix GeneChip Command Console (v4.0.0) was used to create .chp files. All the probe sets on Affymetrix Mouse Gene 2.0 ST array (Mogene-2_0-st-v1.na33.2.mm10) were summarized by Affymetix Expression Console program using robust multi-chip average (RMA) method . After preprocessing steps, data from two batches were combined and their batch effects were corrected using ComBat method Please note that [1] all MP samples are Nf1+/+ (no mutation on Nf1 gene) and the only difference is their ages (1month, 7month) and [2] the 'nf1' in sample title reperesents "neurofibroma type1 disease", not "Nf1 gene".
Project description:To allow accute charaterization of NF1 locus constitutional microdeletion in 70 NF1 patients, a custom array CGH was developped. Goal was to obtain genomic rearrangements fine characterization in order to perform genotype-phenotype correlation in NF1 microdeleted patients. To serve as a reference group in our genotype-phenotype correlation study in NF1 microdeletion patients, non-deleted NF1 patients (i.e. patients with an intragenic NF1 mutation) were also selected from our database. A total of 389 NF1 patients were included in the reference group of non-deleted patients. Multiple logistic regression was performed to test the association of each clinical feature individually with the type of constitutional NF1 mutation (intragenic mutation vs. microdeletion). The phenotypic traits of the 389 reference patients are available in the "GSE19730_control_patient_characteristics.txt" supplementary file on the Series record. NF1 locus microdeletions characterization vs reference sample (pool of six normal control DNAs)
Project description:Neurofibromatosis Type 1 (NF1) is a tumor predisposition syndrome with pleiotropic somatic manifestations, including formation of bone pseudarthrosis after fracture. The pathogenesis of NF1 pseudarthroses remains unclear, though defects in osteogenesis have been posited. Here, we applied time-series single-cell RNA-sequencing (scRNAseq) to patient-matched control and pseudarthrosis-derived primary bone mesenchymal stromal cells (MSCs). We show that osteogenesis occurs in NF1-/- MSCs. In contrast, expression of genetic pathways associated with skeletal mineralization were reduced in NF1-/- cells compared to co-cultured NF1+/- fracture-derived cells.
Project description:Malignant peripheral nerve sheath tumors (MPNSTs) are the leading cause of premature death for patients with Neurofibromatosis type 1 and no approved targeted therapies are available. Transformation from Nf1-null benign plexiform neurofibromas is driven by the loss of the Cdkn2a (Arf) locus. Here, genetically engineered mouse models with floxed Nf1 and combined Nf1 and Arf alleles were used. Schwann cell precursor cells (the tumor cell-of-origin) were isolated from the nerve root (dorsal root ganglia) of embryos at day 13.5. These cells, termed DRG/nerve root neurosphere cells (DNSCs) were established, and either control adenoviral infection (GFP) was performed, or adenoviral Cre-GFP infection used to conditionally ablate Nf1 or Nf1-Arf. mRNA sequencing was performed using Nf1 (control, GFP infected or “GFP”), Nf1 (Cre-GFP infected or “CRE”), or Nf1-Arf (Cre-GFP infected or “ARF”) to evaluate the effects on the transcriptome.