Disruption of local iron homeostasis is a common feature of neurodegenerative diseases. We focused on dopaminergic neurons, asking how iron transport proteins modulate iron homeostasis in vivo. Inactivation of the transmembrane iron exporter ferroportin had no apparent consequences. However, loss of the transferrin receptor 1, involved in iron uptake, caused profound, age-progressive neurodegeneration with features similar to Parkinsons disease. There was gradual loss of dopaminergic projections in the striatum with subsequent death of dopaminergic neurons in the substantia nigra. After depletion of 30% of the neurons the mice developed neurobehavioral parkinsonism, with evidence of mitochondrial dysfunction and impaired mitochondrial autophagy. Molecular analysis revealed strong signatures indicative of attempted axonal regeneration, a metabolic switch to glycolysis and the unfolded protein response. We speculate that cellular iron deficiency may contribute to neurodegeneration in human patients
Altered dopamine metabolism and increased vulnerability to MPTP in mice with partial deficiency of mitochondrial complex I in dopamine neurons.
Age, Specimen part
View SamplesMitochondria are centers of metabolism and signaling whose content and function must adapt to changing cellular environments. The biological signals that initiate mitochondrial restructuring and the cellular processes that drive this adaptive response are largely obscure. To better define these systems, we performed matched quantitative genomic and proteomic analyses of mouse muscle cells as they performed mitochondrial biogenesis. We find that proteins involved in cellular iron homeostasis are highly coordinated with this process, and that depletion of cellular iron results in a rapid, dose-dependent decrease of select mitochondrial protein levels and oxidative capacity. We further show that this process is universal across a broad range of cell types and fully reversed when iron is reintroduced. Collectively, our work reveals that cellular iron is a key regulator of mitochondrial biogenesis, and provides quantitative datasets that can be leveraged to explore post-transcriptional and post-translational processes that are essential for mitochondrial adaptation.
Complementary RNA and protein profiling identifies iron as a key regulator of mitochondrial biogenesis.
Cell line, Treatment
View SamplesIKKbeta is a subunit of the IkB kinase (IKK) complex required for NF-kB activation in response to pro-inflammatory signals. NF-kB regulates the expression of many genes involved in inflammation, immunity and apoptosis, and also controls cell proliferation and differentiation in different tissues; however, its function in skin physiopathology remains controversial. We here report the alterations caused by increased IKKbeta activity in basal cells of the skin of transgenic mice.
IKKbeta leads to an inflammatory skin disease resembling interface dermatitis.
Sex, Age, Specimen part
View SamplesThe ACBP knockout were created by targeted disruption of the gene in mice. The expression profiling was performed on liver tissue from ACBP-/- (KO) and +/+ (WT) mice at the age of 21 days, which in our study is the time immediately before weaning. The mice used for this experiment were taken directly away from their mother. Thus, having free access to chow and breast milk until sacrificed at 8-11am
Disruption of the acyl-CoA-binding protein gene delays hepatic adaptation to metabolic changes at weaning.
Specimen part
View SamplesNeurofibromatosis Type 1 (NF1) patients develop benign neurofibromas and malignant peripheral nerve sheath tumors (MPNST). These incurable peripheral nerve tumors result from loss of NF1 tumor suppressor gene function, causing hyperactive Ras signaling. Activated Ras controls numerous downstream effectors, but specific pathways mediating effects of hyperactive Ras in NF1 tumors are unknown. Cross-species transcriptome analyses of mouse and human neurofibromas and MPNSTs identified global negative feedback of genes that regulate Ras-Raf- MEK- extracellular signal-regulated protein kinase (ERK) signaling in both species. Nonetheless, activation of ERK was sustained in mouse and human neurofibromas and MPNST. PD0325901, a highly selective pharmacological inhibitor of MEK, was used to test whether sustained Ras-Raf-MEK-ERK signaling contributes to neurofibroma growth in the Nf1fl/fl;Dhh-cre mouse model or in NF1 patient MPNST cell xenografts. PD0325901 treatment reduced aberrantly proliferating cells in neurofibroma and MPNST, prolonged survival of mice implanted with human MPNST cells, and shrank neurofibromas in >80% of mice tested. PD0325901 also caused effects on tumor vasculature. Our data demonstrate that deregulated Ras/ERK signaling is critical for the growth of NF1 peripheral nerve tumors and provide strong rationale for testing MEK inhibitors in NF1 clinical trials.
MEK inhibition exhibits efficacy in human and mouse neurofibromatosis tumors.
Specimen part
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