Neuronal migration defects (NMDs) are among the most common and severe brain abnormalities in humans. Lack of disease models in mice or in human cells has hampered the identification of underlying mechanisms. From patients with severe NMDs we generated iPSCs then differentiated neural progenitor cells (NPCs). On artificial extracellular matrix, patient-derived neuronal cells showed defective migration and impaired neurite outgrowth. From a cohort of 107 families with NMDs, sequencing identified two homozygous C-terminal truncating mutations in CTNNA2, encoding aN-catenin, one of three paralogues of the a-catenin family, involved in epithelial integrity and cell polarity. Patient-derived or CRISPR-targeted CTNNA2- mutant neuronal cells showed defective migration and neurite stability. Recombinant aN-catenin was sufficient to bundle purified actin and to suppress the actin-branching activity of ARP2/3. Small molecule inhibitors of ARP2/3 rescued the CTNNA2 neurite defect. Thus, disease modeling in human cells could be used to understand NMD pathogenesis and develop treatments for associated disorders. Overall design: 2 biological replicates per individual (2 iPSC clone differentiations), excluding 1263A, which has one sample
Biallelic loss of human CTNNA2, encoding αN-catenin, leads to ARP2/3 complex overactivity and disordered cortical neuronal migration.
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View SamplesThe mechanical effect of raised intraocular pressure is a recognised stimulus for optic neuropathy in primary open angle glaucoma (POAG). Characteristic extra-cellular matrix (ECM) remodelling accompanies axonal damage in the lamina cribrosa (LC) of the optic nerve head in POAG. Glial cells in the lamina cribrosa may play a role in this process but the precise cellular responses to mechanical forces in this region are unknown. The authors examined global gene expression profiles in lamina cribrosa cells exposed to cyclical mechanical stretch, with an emphasis on ECM genes.
Influence of cyclical mechanical strain on extracellular matrix gene expression in human lamina cribrosa cells in vitro.
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View SamplesBackground: The ability of an organism to repair damages to DNA is inextricably linked to aging and cancer. We have characterized and compared the transcriptome of C. elegans mutants deficient in DNA base excision repair, nucleotide excision repair or both to elucidate the transcriptional changes incurred by the reduction of these repair pathways.
A two-tiered compensatory response to loss of DNA repair modulates aging and stress response pathways.
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View SamplesDuring adipocyte differentiation, significant alternative splicing changes occur in association with the adipogenic process. However, little is known about roles played by splicing factors in this process. We observed that mice deficient for the splicing factor SRSF10 exhibit severely impaired development of subcutaneous white adipose tissue as a result of defects in adipogenic differentiation. To identify splicing events responsible for this, RNA-seq analysis was performed using embryonic fibroblast cells. Several SRSF10-affected splicing events that are implicated in adipogenesis have been identified. Skipping of lipin1 exon 7 is controlled by SRSF10-regulated cis-element located in the constitutive exon 8. The activity of this element depends on the binding of SRSF10 and correlates with the relative abundance of lipin1a mRNA. A series of experiments demonstrated that SRSF10 controls the production of lipin1a and thus promotes adipocyte differentiation. Indeed, lipin1a expression could rescue SRSF10-mediated adipogenic defects. Taken together, our results identify SRSF10 as an essential regulator for adipocyte differentiation and also provide new insights into splicing control by SRSF10 in lipin1 pre-mRNA splicing. Overall design: RNA-seq for wide type (WT) and SRSF10-deficient (KO) mouse MEF cells
SRSF10 regulates alternative splicing and is required for adipocyte differentiation.
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View SamplesThe nematode Caenorhabditis elegans has been used extensively to study responses to DNA damage. In contrast, little is known about DNA repair in this organism. C. elegans is unusual in that it encodes few DNA glycosylases and the uracil-DNA glycosylase (UDG) encoded by the ung-1 gene is the only known UDG. C. elegans could therefore become a valuable model organism for studies of the genetic interaction networks involving base excision repair (BER). As a first step towards characterization of BER in C. elegans, we show that the UNG-1 protein is an active uracil-DNA glycosylase. We demonstrate that an ung-1 mutant has reduced ability to repair uracil-containing DNA but that an alternative Ugi-inhibited activity is present in ung-1 nuclear extracts. Finally, we demonstrate that ung-1 mutants show altered levels of apoptotic cell corpses formed in response to DNA damaging agents. Increased apoptosis in the ung-1 mutant in response to ionizing radiation (IR) suggests that UNG-1 contributes to repair of IR-induced DNA base damage in vivo. Following treatment with paraquat however, the apoptotic corpse-formation was reduced. Gene expression profiling suggests that this phenotype is a consequence of compensatory transcriptomic shifts that modulate oxidative stress responses in the mutant and not an effect of reduced DNA damage signaling.
Loss of Caenorhabditis elegans UNG-1 uracil-DNA glycosylase affects apoptosis in response to DNA damaging agents.
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View SamplesGenetic susceptibility underlies the pathogenesis of cancer. Through genome-wide association studies, we and others have previously identified a novel susceptibility gene, TNFRSF19, which encodes an orphan member of the TNF receptor superfamily, to be associated with nasopharyngeal carcinoma (NPC) and lung cancer risk. Here, we show that TNFRSF19 is highly expressed in NPC and is required for cell proliferation and NPC development. However, unlike most of TNF receptors, TNFRSF19 is not involved in NF-B activation or associated with TRAF proteins. By affinity purification, we identified TGF receptor type-I (TRI) as a specific binding partner for TNFRSF19. TNFRSF19 binds to the kinase domain of TRI in the cytoplasm and thereby blocks the Smad2/3 association with TRI and subsequent signal transduction. Ectopic expression of TNFRSF19 in normal epithelial cells confers resistance to the cell cycle block induced by TGF, whereas knockout of TNFRSF19 in NPC cells unleashes a potent TGF response characterized by upregulation of Smad2/3 phosphorylation and TGF target gene transcription. Furthermore, elevated TNFRSF19 expression correlates with reduced TGF activity and poor prognosis in NPC patients. Our data reveal that gain-of-function of TNFRSF19 in NPC represents a mechanism by which tumor cells evade the growth-inhibitory action of TGF.
TNFRSF19 Inhibits TGFβ Signaling through Interaction with TGFβ Receptor Type I to Promote Tumorigenesis.
Specimen part
View SamplesThe goals of this study aim to reveal functional and phenotypic diversity of leukemia-associated macrophages in response to the microenvironmental cues in mouse T cell acute lymphoblastic leukemia Overall design: Compare Transcriptomes of macrophages in T cell acute leukemia which are suggested as leukemia-associated macrophages (LAMs) with homeostasis
Organ-specific microenvironment modifies diverse functional and phenotypic characteristics of leukemia-associated macrophages in mouse T cell acute lymphoblastic leukemia.
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View SamplesL-3,4-dihydroxyphenylalanine (levodopa) treatment is the major pharmacotherapy for Parkinson's disease. However, almost all patients receiving levodopa eventually develop debilitating involuntary movements (dyskinesia). While it is known that striatal spiny projection neurons (SPNs) are involved in the genesis of this movement disorder, the molecular basis of dyskinesia is not understood. In this study, we identify distinct cell-type-specific gene expression changes that occur in sub-classes of SPNs upon induction of a parkinsonian lesion followed by chronic levodopa treatment. We identify several hundred genes whose expression is correlated with levodopa dose, many of which are under the control of AP-1 and ERK signaling. In spite of homeostatic adaptations involving several signaling modulators, AP-1-dependent gene expression remains highly dysregulated in direct pathway SPNs (dSPNs) upon chronic levodopa treatment. We also discuss which molecular pathways are most likely to dampen abnormal dopaminoceptive signaling in spiny projection neurons, hence providing potential targets for antidyskinetic treatments in Parkinson's disease.
Molecular adaptations of striatal spiny projection neurons during levodopa-induced dyskinesia.
Specimen part, Treatment
View SamplesNeurons in the arcuate nucleus (ARC) sense the fed/fasted state and regulate hunger. ARCAgRP neurons release GABA, NPY and the melanocortin-4 receptor (MC4R) antagonist, AgRP, and are activated by fasting1-4. When stimulated, they rapidly and potently drive hunger5,6. ARCPOMC neurons, in contrast, release the MC4R agonist, a-MSH, and are viewed as the counterpoint to ARCAgRP neurons. They are regulated in an opposite fashion and their activity leads to decreased hunger2,4,7. Together, ARCAgRP and ARCPOMC neurons constitute the ARC feeding center. Against this, however, is the finding that ARCPOMC neurons, unlike ARCAgRP neurons, fail to affect food intake over the timescale of minutes to hours following opto- or chemogenetic stimulation5,8. This suggests a rapidly acting component of the ARC satiety pathway is missing. Here, we show that excitatory ARC neurons identified by expression of vesicular glutamate transporter 2 (VGLUT2) and the oxytocin receptor, unlike ARCPOMC neurons, rapidly cause satiety when chemo- or optogenetically manipulated. These glutamatergic ARC projections synaptically converge with GABAergic ARCAgRP projections on MC4R-expressing neurons in the paraventricular hypothalamus (PVHMC4R neurons), which are known to mediate satiety9. ARCPOMC neurons also send dense projections to the PVH. Importantly, the a-MSH they release post-synaptically potentiates glutamatergic synaptic activity onto PVHMC4R neurons – including that emanating from ARCVglut2 neurons. This suggests a means by which a-MSH can bring about satiety – via postsynaptic potentiation of this novel ARCVglut2 to PVHMC4R satiety circuit. Thus, while fast (GABA and NPY) and slow (AgRP) ARC hunger signals are delivered together by ARCAgRP neurons10,11, the temporally analogous satiety signals from the ARC, glutamate and a-MSH, are delivered separately by two parallel, interacting projections (from ARCVGLUT2 and ARCPOMC neurons). Discovery of this rapidly acting excitatory ARC ? PVH satiety circuit, and its regulation by a-MSH, provides new insight into regulation of hunger/satiety. Overall design: 23 samples representing single neurons dissociated from the arcuate hypothalamus of two young adult male vGLUT2-IRES-Cre mice
A rapidly acting glutamatergic ARC→PVH satiety circuit postsynaptically regulated by α-MSH.
Specimen part, Cell line, Subject
View SamplesWe demonstrate that transcriptomic profiling of the NER mutant ercc-1 offers better understanding of the complex phenotypes of ercc-1 deficiency in C. elegans, as it does in mammalian models. There is a transcriptomic shift in ercc-1 mutants that suggests a stochastic impairment of growth and development, with a shift towards a higher proportion of males in the population. Extensive phenotypic analyses confirm that NER deficiency in C. elegans leads to severe developmental and growth defects and a reduced replicative lifespan, although post-mitotic lifespan is not affected. Results suggest that these defects are caused by an inability to cope with randomly occurring DNA damage, which may interfere with transcription and replication.
DNA damage leads to progressive replicative decline but extends the life span of long-lived mutant animals.
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