In Drosophila, fibrillar flight muscles (IFMs) enable flight, while tubular muscles mediate other body movements. Here, we use RNA-sequencing and isoform-specific reporters to show that spalt major (salm) determines fibrillar muscle physiology by regulating transcription and alternative splicing of a large set of sarcomeric proteins. We identify the RNA binding protein Arrest (Aret, Bruno) as downstream of salm. Aret shuttles between cytoplasm and nuclei, and is essential for myofibril maturation and sarcomere growth of IFMs. Molecularly, Aret regulates IFM-specific transcription and splicing of various sarcomeric targets, including Stretchin and wupA (TnI), and thus maintains muscle fiber integrity. As Aret and its sarcomeric targets are evolutionarily conserved, similar principles may regulate mammalian muscle morphogenesis. Overall design: 9 samples from Drosophila melanogaster were analyzed in duplicate: control dissected wildtype flight muscle at 30h APF, 72h APF and 0 day adult, jump muscle and whole leg from 1d adult and RNAi/mutant conditions for salm (1d flight muscle) and aret (30h, 72h and 1d flight muscle)
The RNA-binding protein Arrest (Bruno) regulates alternative splicing to enable myofibril maturation in Drosophila flight muscle.
Subject
View SamplesMuscles organise a pseudo-crystalline array of actin, myosin and titin filaments to build force-producing sarcomeres. To study how sarcomeres are built, we performed mRNA-sequencing of developing Drosophila flight muscles and identified 40 distinct expression profile clusters. Strikingly, two clusters are strongly enriched for sarcomeric components. Temporal gene expression together with detailed morphological analysis enabled us to define two distinct phases of sarcomere development, both of which require the transcriptional regulator Spalt major. During the first sarcomere formation phase, 2.0 µm long immature sarcomeres assemble myofibrils that spontaneously contract. In the second sarcomere maturation phase, sarcomeres grow to their final 3.2 µm length and 1.5 µm diameter and acquire stretch-sensitivity. Interestingly, the final number of myofibrils per flight muscle fiber is determined at the onset of the first phase and remains constant. Together, this defines a biphasic mode of sarcomere and myofibril morphogenesis – a new concept which may also apply to vertebrate muscle or heart development. Overall design: Part I: An 8-point timecourse of wild-type flight muscle development in Drosophila melanogaster was analyzed with duplicates/triplicates for each timepoint Part II: A Mef2-Gal4 x salmIR timecourse in duplicate at 4 timepoints was compared to wild-type flight muscle
A transcriptomics resource reveals a transcriptional transition during ordered sarcomere morphogenesis in flight muscle.
Specimen part, Subject
View SamplesFungal infections are major causes of morbidity and mortality, especially in immunocompromised individuals. The innate immune system senses fungal pathogens through a family of Syk-coupled C-type lectin receptors (CLRs), which signal through the conserved immune adapter Card9. Although Card9 complexes are essential for antifungal defense in humans and mice, the mechanisms that couple CLR-proximal events to Card9 control are not well defined. Here, using a proteomic approach, we identified Vav proteins as key activators of the Card9 pathway. Vav1, Vav2 and Vav3 cooperate downstream of Dectin-1, Dectin-2 and Mincle to selectively engage Card9 for NF-?B control and proinflammatory gene transcription but are not involved in MAPK activation. Although Vav family members show functional redundancy, Vav1/2/3 triple-deficient cells are severely impaired for NF-?B and cytokine responses upon stimulation with CLR agonists or hyphae, and Vav1/2/3-/- mice phenocopy Card9-/- animals with extreme susceptibility to fungi and rapid mortality upon Candida albicans infection. In this context, Vav3 is the single most important Vav in mice, and a polymorphism in human VAV3 is associated with susceptibility to candidemia in patients. Our results reveal a molecular mechanism for CLR-mediated Card9 regulation that controls innate immunity to fungal infections. Overall design: RNA profiles of unstimulated or Curdlan-stimulated bone marrow-derived dendritic cells (BMDCs) from wild type (WT) and Vav1/2/3-/- (VAV KO) mice were generated by deep sequencing, in triplicate, using Illumina HiSeq 2000.
Vav Proteins Are Key Regulators of Card9 Signaling for Innate Antifungal Immunity.
Specimen part, Cell line, Subject
View SamplesTORC1 is a structurally and functionally conserved multiprotein complex that regulates many aspects of eukaryote growth including the synthesis and assembly of ribosomes. The protein kinase activity of this complex is responsive to environmental cues and is potently inhibited by the natural product macrolide rapamycin. Insights into how TORC1 regulates growth have been provided with the recent identification of the rapamycin-sensitive phosphoproteome in yeast. Building on these data, we show here that Sch9, an AGC family kinase and direct substrate of TORC1, promotes ribosome biogenesis (ribi) and ribosomal protein (RP) gene expression via direct inhibitory phosphorylation of three transcription repressors, Stb3, Dot6 and Tod6. Dephosphorylation of these factors allows them to recruit the RPD3L histone deactelyase complex to ribi/RP gene promoters. Since rRNA and tRNA transcription are also under its control, Sch9 appears to be well positioned to coordinately regulate transcriptional aspects of ribosome biogenesis. Overall design: mRNA-Seq of 8 S. cerevisiae strains treated with either DMSO alone or 1NM-PP1, a small molecule inhibitor for analog-sensitive kinases such as sch9-as.
Sch9 regulates ribosome biogenesis via Stb3, Dot6 and Tod6 and the histone deacetylase complex RPD3L.
Specimen part, Cell line, Treatment, Subject
View SamplesMicroglia play important roles in developmental and homeostatic brain function, and influence the establishment and progression of many neurological disorders. Here, we demonstrate that renewable human iPSCs can be efficiently differentiated to microglial-like cells (iMGL) to study neurological diseases, such as Alzheimer''s disease (AD). We find that iMGLs develop in vitro similarly to microglia in vivo and whole transcriptome analysis demonstrates that they are highly similar to adult and fetal human microglia. Functional assessment of iMGLs reveal that they secrete cytokines in response to inflammatory stimuli, migrate and undergo calcium transients, and robustly phagocytose CNS substrates. We also show novel use of iMGLs to examine the effects of fibrillar Aß and brain-derived tau oligomers on AD-related gene expression and to interrogate mechanisms involved in synaptic pruning. Taken together, these findings demonstrate that iMGLs can be used in high-throughput studies of microglial function, providing important new insight into human neurological disease. Overall design: Human cells were collected and analyzed for gene expression using RNA-seq.
iPSC-Derived Human Microglia-like Cells to Study Neurological Diseases.
Specimen part, Subject
View SamplesTransgenic animals were engineered to express human amyloid peptide controlled by a muscle-specific, heat-inducible promoter. At low temperatures (16C) Abeta expression is minimal, while at higher temperatures (20-25C) Abeta accummulates in large quantities and causes paralysis.
Identifying Aβ-specific pathogenic mechanisms using a nematode model of Alzheimer's disease.
Time
View SamplesAtrial fibrillation (AF) is a progressive arrhythmia for which current therapy is inadequate. During AF, rapid stimulation causes atrial remodeling that promotes further AF. The cellular signals that trigger this process remain poorly understood, however, and elucidation of these factors would likely identify new therapeutic targets. We have previously shown that immortalized mouse atrial (HL-1) myocytes subjected to 24 hr of rapid stimulation in culture undergo remodeling similar to that seen in animal models of atrial tachycardia (AT) and human AF. This preparation is devoid of confounding in vivo variables that can modulate gene expression (e.g., hemodynamics). Therefore, we investigated the transcriptional profile associated with early atrial cell remodeling. RNA was harvested from HL-1 cells cultured for 24 hr in the absence and presence of rapid stimulation and subjected to microarray analysis. Data were normalized using Robust Multichip Analysis (RMA), and genes exhibiting significant differential expression were identified using the Significance Analysis of Microarrays (SAM) method. Using this approach, 919 genes were identified that were significantly altered with rapid stimulation (763 up-regulated and 156 down-regulated). For many individual transcripts, changes typical of AF/AT were observed, with marked up-regulation of genes encoding BNP and ANP precursors, heat shock proteins, and MAP kinases, while novel signaling pathways and molecules were also identified. Both stress and survival response were evident, as well as up-regulation of multiple transcription factors. Genes were also functionally classified based on cellular component, biologic process, and molecular function using the Gene Ontology database to permit direct comparison of our data with other gene sets regulated in human AF and experimental AT. For broad categories of genes grouped by functional classification, there was striking conservation between rapidly stimulated HL-1 cells and AF/AT. Results were confirmed using real-time quantitative RT-PCR on 13 genes selected by physiological relevance in AF/AT and regulation in the microarray analysis (up, down, and nonregulated). Rapidly-stimulated atrial myocytes provide a complementary experimental paradigm to explore the initial cellular signals in AT remodeling to identify novel targets in the treatment of AF.
Transcriptional remodeling of rapidly stimulated HL-1 atrial myocytes exhibits concordance with human atrial fibrillation.
No sample metadata fields
View SamplesDespite inheritance of hypertension in families, identifying genetic mechanisms predisposing individuals to hypertension has remained challenging. The effects of single genes contributing to the development of hypertension may not be readily detected in individuals whose genomes also contain other genetic factors that resist hypertension. By using a highly permissive rat genome for inherited hypertension, we demonstrate that increased expression of one such gene, Rififylin (Rffl), is a novel inherited risk factor for hypertension and increased mortality. Animals overexpressing Rffl demonstrated delayed endocytic recycling, accumulated polyubiquitinated proteins, increased beats/min of neonatal cardiomyocytes, had shorter QT-intervals and developed salt-insensitive hypertension very early in their life (50-52 days). Thus, the discovery of a physiological link between overexpression of rififylin and the development of hypertension constitutes a novel mechanism that could be targeted for rectifying normal QT-interval and preventing hypertension.
Augmented rififylin is a risk factor linked to aberrant cardiomyocyte function, short-QT interval and hypertension.
Age, Specimen part
View SamplesEvidence from multiple linkage and genome-wide association studies suggest that human chromosome 2 (HSA2) contains alleles that influence blood pressure (BP). Homologous to a large segment of HSA2 is rat chromosome 9 (RNO9), to which a BP quantitative trait locus (QTL) was previously mapped. The objective of the current study was to further resolve this BP QTL. Eleven congenic strains with introgressed segments spanning <81.8kb to <1.33Mb were developed by introgressing genomic segments of RNO9 from the Dahl salt-resistant (R) rat onto the genome of the Dahl salt-sensitive (S) rat and tested for BP. The congenic strain with the shortest introgressed segment spanning <81.8kb significantly lowered BP of the hypertensive S rat by 25 mm Hg and significantly increased its mean survival by 45 days. In contrast, two other congenic strains had increased BP compared with the S. We focused on the <81.8kb congenic strain which represents the shortest genomic segment to which a BP QTL has been definitively mapped to date in any species. Sequencing of this entire region in both S and R rats detected 563 variants. The region did not contain any known or predicted rat protein coding genes. Further, a whole genome renal transcriptome analysis between S and the <81.8kb S.R congenic strain revealed alterations in several critical genes implicated in renal homeostasis. Taken together, our results provide the basis for future studies to examine the relationship between the candidate variants within the QTL region and the renal differentially expressed genes as potential causal mechanisms for BP regulation.
Defining a rat blood pressure quantitative trait locus to a &lt;81.8 kb congenic segment: comprehensive sequencing and renal transcriptome analysis.
Age, Specimen part
View SamplesWe aimed to investigate gene expression associated with radiosensitisation of normoxic and hypoxic prostate cancer cells by the class I/II histone deacetylase inhibitor (HDACi) vorinostat.
Hypoxia-independent gene expression signature associated with radiosensitisation of prostate cancer cell lines by histone deacetylase inhibition.
Cell line, Treatment
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