Project description:Mutations in the MAPT gene that encodes tau lead to frontotemporal dementia (FTD) with pathology evident in both cerebral neurons and glia. Human cerebral organoids (hCOs) from individuals harboring pathogenic tau mutations can reveal the earliest downstream effects on molecular pathways within a developmental context generating interacting neurons and glia. We found that in hCOs carrying the V337M and R406W tau mutations, the cholesterol biosynthesis pathway in astrocytes was the top upregulated gene set compared to isogenic controls by scRNAseq. The 15 upregulated genes included HMGCR, ACAT2, STARD4, LDLR, and SREBF2. This result was confirmed in a homozygous R406W mutant cell line, by immunostaining and sterol measurements. Cholesterol abundance in the brain is tightly regulated by efflux and cholesterol biosynthetic enzyme levels in astrocytes, and dysregulation can cause aberrant phosphorylation of tau. Our findings suggest that cholesterol dyshomeostasis is an early event in the etiology of neurodegeneration caused by tau mutations.
Project description:Maternal obesity raises the risk of high-cholesterol exposure for their offspring. Studies in cohorts and animal models report that maternal obesity could increase the risk of neurodevelopmental disorders (NDDs) in offspring including intellectual disabilities and autism spectrum disorders (ASD). However, whether exposure to high cholesterol is responsible for brain developmental defects, as well as its underlying mechanism, is still unclear. Here, we constructed a cholesterol exposure model utilizing hiPSC-derived cerebral organoids by exogenously adding cholesterol into the culture system. We preformed scRNA sequence analysis to explore the gene expression changes in brain organoids under additional cholesterol exposure.
Project description:Cholesterol is required for oligodendrocyte maturation and CNS myelination. Here, we demonstrate an essential role for the intracellular cholesterol transporter NPC1 in these processes. NPC1 functions in late endosomes and lysosomes to efflux unesterified cholesterol, and its deficiency causes Niemann-Pick disease Type C, an autosomal recessive lysosomal disorder characterized by progressive neurodegeneration and early death. To identify cell types and pathways affected early in pathogenesis, we performed single nuclear RNA-seq on the forebrain of Npc1-/- mice at P16. This analysis uncovered striking transcriptional changes in the oligodendrocyte lineage during the period of developmental myelination, accompanied by diminished maturation of myelinating oligodendrocytes. Unexpectedly, we identified a significant upregulation of genes associated with neurogenesis and synapse formation in Npc1-/- oligodendrocyte lineage cells, reflecting diminished gene silencing by H3K27me3 and H3K9me3.
Project description:Differential gene expression of cerebral cortex might be responsible for distinct neurovascular developments between different mouse strains We used Affymetrix microarray to explore the global gene expression patterns of mouse cerebral cortex of different mouse strains at two developmental stages Cerebral cortex from two mouse strains [C57BL/6J(B6) and C3H/J (C3H)] at post-natal day 1 (p1) and post-natal 11 weeks (11 wk) were harvested for microarray experiments
Project description:Macrophage cholesterol homeostasis is crucial for health and disease and has been linked to the lipid-peroxidizing enzyme arachidonate 15-lipoxygenase type B (ALOX15B), albeit molecular mechanisms remain obscure. We performed global transcriptome and immunofluorescence analysis in ALOX15B-silenced primary human macrophages and observed a reduction of nuclear sterol regulatory element-binding protein (SREBP) 2, the master transcription factor of cellular cholesterol biosynthesis. Consequently, SREBP2-target gene expression was reduced as were the sterol biosynthetic intermediates desmosterol and lathosterol as well as 25- and 27-hydroxycholesterol. Mechanistically, suppression of ALOX15B reduced lipid peroxidation in primary human macrophages and thereby attenuated activation of mitogen-activated protein kinase ERK1/2, which lowered SREBP2 abundance and activity. Low nuclear SREBP2 rendered both, ALOX15B-silenced and ERK1/2-inhibited macrophages refractory to SREBP2 activation upon blocking the NPC intracellular cholesterol transporter 1. These studies suggest a regulatory mechanism controlling macrophage cholesterol homeostasis based on ALOX15B-mediated lipid peroxidation and concomitant ERK1/2 activation.
Project description:Alternative splicing regulates over 90% of multiexon mammlian genes, but its role in specifying neural progenitor cell (NPC) fates has not been explored. Our analyses of purified mouse NPCs and neurons from developing cerebral cortices revealed hundreds of conserved and differentially spliced exons that add or remove key protein domains, especially in genes regulating the cytoskeleton.
Project description:Cholesterol is required for oligodendrocyte maturation and CNS myelination. Here, we demonstrate an essential role for the intracellular cholesterol transporter NPC1 in these processes. NPC1 functions in late endosomes and lysosomes to efflux unesterified cholesterol, and its deficiency causes Niemann-Pick disease Type C, an autosomal recessive lysosomal disorder characterized by progressive neurodegeneration and early death. To identify cell types and pathways affected early in pathogenesis, we performed single nuclear RNA-seq on the forebrain of Npc1-/- mice at P16. This analysis uncovered striking transcriptional changes in the oligodendrocyte lineage during the period of developmental myelination, accompanied by diminished maturation of myelinating oligodendrocytes. Unexpectedly, we identified a significant upregulation of genes associated with neurogenesis and synapse formation in Npc1-/- oligodendrocyte lineage cells, reflecting diminished gene silencing by H3K27me3 and H3K9me3. Npc1-/- oligodendrocyte progenitor cells reproduced impaired maturation in vitro and this phenotype was rescued by treatment with GSK-J4, a small molecule inhibitor of H3K27 demethylases. This study sought to determine the genes being directly impacted by the epigenetic dysfunction at H3K27.
Project description:Differential gene expression of cerebral cortex might be responsible for distinct neurovascular developments between different mouse strains We used Affymetrix microarray to explore the global gene expression patterns of mouse cerebral cortex of different mouse strains at two developmental stages
Project description:<p><strong>BACKGROUND:</strong> The protozoan parasite Toxoplasma gondii infects and alters the neurotransmission in cerebral cortex and other brain regions, leading to neurobehavioral and neuropathologic changes in humans and animals. However, the molecules that contribute to these changes remain largely unknown.</p><p><strong>METHODS:</strong> We have investigated the impact of T. gondii infection on the overall metabolism of mouse cerebral cortex. Mass-spectrometry-based metabolomics and multivariate statistical analysis were employed to discover metabolomic signatures that discriminate between cerebral cortex of T. gondii-infected and uninfected control mice.</p><p><strong>RESULTS:</strong> Our results identified 73, 67 and 276 differentially abundant metabolites, which were involved in 25, 37 and 64 pathways at 7, 14 and 21 days post-infection (dpi), respectively. Metabolites in the unsaturated fatty acid biosynthesis pathway were upregulated as the infection progressed, indicating that T. gondii induces the biosynthesis of unsaturated fatty acids to promote its own growth and survival. Some of the downregulated metabolites were related to pathways, such as steroid hormone biosynthesis and arachidonic acid metabolism. Nine metabolites were identified as T. gondii responsive metabolites, namely galactosylsphingosine, arachidonic acid, LysoSM(d18:1), L-palmitoylcarnitine, calcitetrol, 27-Deoxy-5b-cyprinol, L-homophenylalanine, oleic acid and ceramide (d18:1/16:0).</p><p><strong>CONCLUSIONS:</strong> Our data provide novel insight into the dysregulation of the metabolism of the mouse cerebral cortex during T. gondii infection and have important implications for studies of T. gondii pathogenesis.</p>