Background: Mutations in the cone-rod-homeobox protein CRX are typically associated with dominant blinding retinopathies with variable age of onset and severity. Five well-characterized mouse models carrying different Crx mutations show a wide range of disease phenotypes. To determine if the phenotype variability correlates with distinct changes in CRX target gene expression, we perform RNA-seq analyses on three of these models and compare the results with published data. Results: Despite dramatic phenotypic differences between the three models tested, graded expression changes in shared sets of genes are detected. Phenotype severity correlates with the down-regulation of genes encoding key rod and cone phototransduction proteins. Interestingly, in increasingly severe mouse models, the transcription of many rod-enriched genes decreases decrementally, whereas that of cone-enriched genes increases incrementally. Unlike down-regulated genes, which show a high degree of CRX binding and dynamic epigenetic profiles in normal retinas, the up-regulated cone-enriched genes do not correlate with direct activity of CRX, but instead likely reflect a change in rod cell-fate integrity. Furthermore, these analyses describe the impact of minor gene expression changes on the phenotype, as two mutants showed marginally distinguishable expression patterns but huge phenotypic differences, including distinct mechanisms of retinal degeneration. Conclusions: Our results implicate a threshold effect of gene expression level on photoreceptor function and survival, highlight the importance of CRX in photoreceptor subtype development and maintenance, and provide a molecular basis for phenotype variability in CRX-associated retinopathies. Overall design: All genotypes were analyzed in triplicate. Heterozygous and homozygous mutants were all sequenced at P10, the control for which is the P10 C57BL6/J data. Heterozygous mutants were also analyzed at P21, the control for which is the P21 C57BL6/J data.
Graded gene expression changes determine phenotype severity in mouse models of CRX-associated retinopathies.
No sample metadata fields
View SamplesSingle-stranded DNA or RNA sequences rich in guanine (G) can adopt non-canonical structures known as G-quadruplexes (G4). G4 in the mitochondrial genome are heavy-strand enriched and have been associated with the formation of deletion breakpoints that cause mitochondrial diseases. However, the functional role of G4 structures in mitochondria remains unclear. Here, we have identified RHPS4 as a G4-specific ligand that localizes to mitochondria and causes replication pausing, with mitochondrial DNA (mtDNA) depletion occurring at higher dosage. We further show that RHPS4 interferes with mitochondrial transcript elongation at low doses, leading to respiratory complex depletion. These unprecedented observations suggest that G4 motifs modulate mitochondrial transcription and replication efficiency. Using the differential effects of high vs low RHPS4 dosing, we characterized gene expression pathway responses to mitochondrial transcription inhibition or mitochondrial genome depletion. Importantly, a human mtDNA mutation that increases G4 formation potential strongly enhanced the RHPS4-mediated mitochondrial respiratory defect. We propose that abnormal G4 dynamics may contribute to mtDNA instability and gene expression defects, particularly in the presence of mitochondrial mutations that enhance the G4 formation. Overall design: Total RNA was extracted from the mouse embryonic fibroblasts (MEFs) stimulated with 0um (n=3), 2um (n=3), and 10um (n=2) RHPS4. Total stranded RNA libraries (ribo-depleted) were generated and sequenced on the Illumina NextSeq 500 NGS platform. RNA-seq data was analyzed for differentially expressed genes between groups of samples.
G-quadruplex dynamics contribute to regulation of mitochondrial gene expression.
Subject
View SamplesThe aim was to identify transcripts that are poorly translated upon knockdown of DENR. Lysates from control (GFP) and DENR knockdown S2 cells were run on polysome gradients.
DENR-MCT-1 promotes translation re-initiation downstream of uORFs to control tissue growth.
Specimen part, Disease, Treatment
View SamplesAccute stretch and tachycardia are capable of inducing pathological excitation transcription coupling - an early invent before structural cardiac remodeling which transitions to heart failure. The sodium calcium exchanger is a key player in maintaining calcium homeostasis and is implicated in pathological signaling during heart failure.
The role of stretch, tachycardia and sodium-calcium exchanger in induction of early cardiac remodelling.
Specimen part, Treatment
View SamplesWe report RNA-Seq analysis of the transcriptome of retinas and RPE/choroids from Abca4 knockout, Abca4 L541P;A1038V knockin and control wild type mice in order to better understand changes in gene regulation that could lead to retinal pathology in mice with ABCA4 deficiency/defect. Overall design: Retinal and RPE/choroidal mRNA profiles of 30-day-old wild type (WT), Abca4-/- and Abca4L541P;A1038V/L541P;A1038V mice were generated by RNA-Seq, using Illumina Hiseq 2500
Protein misfolding and the pathogenesis of ABCA4-associated retinal degenerations.
No sample metadata fields
View SamplesIntracranial aneurysms tend to form at bifurcation apices, where flow impingement causes high frictional force (or wall shear stress, WSS) and flow acceleration and deceleration that create positive and negative streamwise gradients in WSS (WSSG), respectively. In vivo, intracranial aneurysms initiate under high WSS and positive WSSG. Little is known about the responses of endothelial cells (ECs) to either positive or negative WSSG under high WSS conditions. We used cDNA microarrays to profile EC gene expression exposed to positive WSSG vs. negative WSSG for 24 hours in a flow chamber with converging and diverging channels, respectively. WSS varied between 3.5 and 28.4 Pa in each gradient channel. GO and biological pathway analysis indicated that positive WSSG favored proliferation, apoptosis, and extracellular matrix processing while decreasing expression of pro-inflammatory genes. A subset of characteristic genes was validated using qPCR: Genes for ADAMTS1, CKAP2 and NCEH1 had higher expression under positive WSSG compared to negative WSSG while TAGLN, THBS1, VCAM1, CCL2, and CSF2 had lower expression. To determine if these patterns of expression are also exhibited in vivo, we tested whether the extracellular matrix related protein ADAMTS1 and proliferation were modulated by positive WSSG during intracranial aneurysm initiation. An aneurysm was induced at the basiliar terminus in rabbits by bilateral carotid ligation. WSSG at the bifurcation was determined by computational fluid dynamic simulations from 3D angiography and mapped on immunofluorescence staining for ADAMTS1 and the proliferation marker, Ki-67. Endothelial ADAMTS1 protein and Ki-67 were significantly higher in regions with positive WSSG compared to adjacent sites where WSSG was negative. Our results indicate that WSSG can elicit distinct gene expression profiles in ECs. Increased matrix processing and high levels of proliferation under positive WSSG could contribute to intracranial aneurysm initiation by causing transient gaps in the endothelium or disrupting EC signals to smooth muscle cells.
Differential gene expression by endothelial cells under positive and negative streamwise gradients of high wall shear stress.
Specimen part
View SamplesDendritic cells (DCs) and macrophages (MPs) are important for immunological homeostasis in the colon. We found that F4/80hi CX3CR1hi (CD11b+CD103-) cells account for 80% of mouse colonic lamina propria (cLP) MHC-IIhi cells. Both CD11c+ and CD11c- cells within this population were identified as MPs based on multiple criteria, including a MP transcriptome revealed by microarray analysis. These MPs constitutively released high levels of IL-10 at least partially in response to the microbiota via an MyD88-independent mechanism. In contrast, cells expressing low to intermediate levels of F4/80 and CX3CR1 were identified as DCs, based on phenotypic and functional analysis and comprise three separate CD11chi cell populations: CD103+CX3CR1-CD11b- DCs, CD103+CX3CR1-CD11b+ DCs and CD103-CX3CR1intCD11b+ DCs. In non-inflammatory conditions, Ly6Chi monocytes differentiated primarily into CD11c+, but not CD11c- MPs. In contrast, during colitis, Ly6Chi monocytes massively invaded the colon and differentiated into pro-inflammatory CD103-CX3CR1intCD11b+ DCs, which produced high levels of IL-12, IL-23, iNOS and TNF. These findings demonstrate the dual capacity of Ly6Chi blood monocytes to differentiate into either regulatory MPs or inflammatory DCs in the colon, and that the balance of these immunologically antagonistic cell types is dictated by microenvironmental conditions.
Inflammation switches the differentiation program of Ly6Chi monocytes from antiinflammatory macrophages to inflammatory dendritic cells in the colon.
No sample metadata fields
View SamplesChronic high flow can induce arterial remodeling, and this effect is mediated by endothelial cells (ECs) responding to wall shear stress (WSS). To assess how WSS above physiological normal levels affects ECs, we used DNA microarrays to profile EC gene expression under various flow conditions. Cultured bovine aortic ECs were exposed to no flow (0 Pa), normal WSS (2 Pa) and very high WSS (10 Pa) for 24 hrs. Very high WSS induced a distinct expression profile when compared to both no flow and normal WSS. Gene ontology and biological pathway analysis revealed that high WSS modulated gene expression in ways that promote an anti-coagulant, anti-inflammatory, proliferative and pro-matrix remodeling phenotype. A subset of characteristic genes was validated using quantitative polymerase chain reaction (qPCR): Very high WSS upregulated ADAMTS1, PLAU (uPA), PLAT (tPA) and TIMP3, all of which are involved in extracellular matrix processing, with PLAT and PLAU also contributing to fibrinolysis. Downregulated genes included chemokines CXCL5 and IL-8 and the adhesive glycoprotein THBS1 (TSP1). Expressions of ADAMTS1 and uPA proteins were assessed by immunhistochemistry in rabbit basilar arteries experiencing increased flow after bilaterial carotid artery ligation. Both proteins were significantly increased when WSS was elevated compared to sham control animals. Our results indicate that very high WSS elicits a unique transcriptional profile in ECs that favors particular cell functions and pathways that are important in vessel homeostasis under increased flow. In addition, we identify specific molecular targets that are likely to contribute to adaptive remodeling under elevated flow conditions.
Endothelial cells express a unique transcriptional profile under very high wall shear stress known to induce expansive arterial remodeling.
Specimen part
View SamplesWe identified a congenic mouse with an introgressed region from the A/J donor inbred strain on an inbred C57BL/6J background that showed a reduced locomotor stimulant response to methamphetamine. We conducted microarray analysis of the striatum from drug-naive female and male mice that were 6-9 weeks old. The congenic region is on chromosome 11 and spans approximately 84-96 Mb. There were two groups of mice used in the analysis: B6 control mice versus congenic mice. Congenic mice were collapsed across heterozygous and homozygous genotypes.
Congenic dissection of a major QTL for methamphetamine sensitivity implicates epistasis.
Sex
View SamplesThe inhibitor of DNA binding 2 (Id2) is essential for NK cell development with its canonical role in this pathway being to antagonize E-proteins, silencing E-box gene expression and subsequent commitment to the T and B cell lineages. However, how E-box genes prevent NK cell development and homeostasis remains enigmatic. Here we identify a key role for Id2 in regulating the threshold for IL-15 receptor signaling and homeostasis of NK cells by repressing multiple E-protein target genes including Socs3. Deletion of Id2 in mature NK cells was incompatible with their homeostasis due to impaired IL-15 receptor signaling. Id2-null NK cells displayed impaired IL-15 mediated JAK1/STAT5 phosphorylation, compromised metabolic function and enhanced apoptosis. Remarkably, Id2-null NK cell homeostasis could be fully rescued in vivo by IL-15 receptor stimulation and partially rescued by genetic ablation of Socs3. During normal NK cell maturation we observed an inverse correlation between the expression levels of E-protein target genes and Id2. These results shift the current paradigm on the role of Id2, indicating that it is not only required to antagonize E-proteins during NK cell commitment, but constantly required to titrate E-protein activity to regulate NK cell fitness and responsiveness to IL-15. Overall design: Transcriptional profiling of wild type and Id2-null natural killer (NK) cells using RNA sequencing
The Helix-Loop-Helix Protein ID2 Governs NK Cell Fate by Tuning Their Sensitivity to Interleukin-15.
Specimen part, Cell line, Subject
View Samples