scholarly journals Transcriptional responses to hyperplastic MRL signalling in Drosophila

Open Biology ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 160306 ◽  
Author(s):  
Vincent Jonchère ◽  
Nada Alqadri ◽  
John Herbert ◽  
Lauren Dodgson ◽  
David Mason ◽  
...  
Keyword(s):  
Serum Response Factor ◽  
Transcriptional Response ◽  
Size Control ◽  
Actin Dynamics ◽  
Transcriptional Responses ◽  
Rna Profiling ◽  
Related Transcription Factor ◽  
Transcriptional Changes ◽  
Wing Discs

Recent work has implicated the actin cytoskeleton in tissue size control and tumourigenesis, but how changes in actin dynamics contribute to hyperplastic growth is still unclear. Overexpression of Pico, the only Drosophila Mig-10/RIAM/Lamellipodin adapter protein family member, has been linked to tissue overgrowth via its effect on the myocardin-related transcription factor (Mrtf), an F-actin sensor capable of activating serum response factor (SRF). Transcriptional changes induced by acute Mrtf/SRF signalling have been largely linked to actin biosynthesis and cytoskeletal regulation. However, by RNA profiling, we find that the common response to chronic mrtf and pico overexpression in wing discs was upregulation of ribosome protein and mitochondrial genes, which are conserved targets for Mrtf/SRF and are known growth drivers. Consistent with their ability to induce a common transcriptional response and activate SRF signalling in vitro , we found that both pico and mrtf stimulate expression of an SRF-responsive reporter gene in wing discs. In a functional genetic screen, we also identified deterin , which encodes Drosophila Survivin, as a putative Mrtf/SRF target that is necessary for pico -mediated tissue overgrowth by suppressing proliferation-associated cell death. Taken together, our findings raise the possibility that distinct targets of Mrtf/SRF may be transcriptionally induced depending on the duration of upstream signalling.

scholarly journals Myocardin-Related Transcription Factor A Activation by Competition with WH2 Domain Proteins for Actin Binding

2016 ◽  
Vol 36 (10) ◽  
pp. 1526-1539 ◽  
Author(s):  
Julia Weissbach ◽  
Franziska Schikora ◽  
Anja Weber ◽  
Michael Kessels ◽  
Guido Posern
Keyword(s):  
Serum Response Factor ◽  
De Novo ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Serum Stimulation ◽  
Competitive Mechanism ◽  
Related Transcription Factor ◽  
Simultaneous Inhibition ◽  
Serum Response

The myocardin-related transcription factors (MRTFs) are coactivators of serum response factor (SRF)-mediated gene expression. Activation of MRTF-A occurs in response to alterations in actin dynamics and critically requires the dissociation of repressive G-actin–MRTF-A complexes. However, the mechanism leading to the release of MRTF-A remains unclear. Here we show that WH2 domains compete directly with MRTF-A for actin binding. Actin nucleation-promoting factors, such as N-WASP and WAVE2, as well as isolated WH2 domains, including those of Spire2 and Cobl, activate MRTF-A independently of changes in actin dynamics. Simultaneous inhibition of Arp2-Arp3 or mutation of the CA region only partially reduces MRTF-A activation by N-WASP and WAVE2. Recombinant WH2 domains and the RPEL domain of MRTF-A bind mutually exclusively to cellular and purified G-actinin vitro. The competition by different WH2 domains correlates with MRTF-SRF activation. Following serum stimulation, nonpolymerizable actin dissociates from MRTF-A, andde novoformation of the G-actin–RPEL complex is impaired by a transferable factor. Our work demonstrates that WH2 domains activate MRTF-A and contribute to target gene regulation by a competitive mechanism, independently of their role in actin filament formation.

scholarly journals Role of the cytoskeleton in muscle transcriptional responses to altered use

2013 ◽  
Vol 45 (8) ◽  
pp. 321-331 ◽  
Author(s):  
Gretchen A. Meyer ◽  
Simon Schenk ◽  
Richard L. Lieber
Keyword(s):  
Mechanical Response ◽  
Fiber Type ◽  
Transcriptional Response ◽  
Primary Component ◽  
Transcriptional Responses ◽  
Expression Of Genes ◽  
Elevated Expression ◽  
Transcriptional Changes ◽  
Type Shift ◽  
Future Work

In this work, the interaction between the loss of a primary component of the skeletal muscle cytoskeleton, desmin, and two common physiological stressors, acute mechanical injury and aging, were investigated at the transcriptional, protein, and whole muscle levels. The transcriptional response of desmin knockout ( des −/−) plantarflexors to a bout of 50 eccentric contractions (ECCs) showed substantial overlap with the response in wild-type ( wt) muscle. However, changes in the expression of genes involved in muscle response to injury were blunted in adult des −/− muscle compared with wt (fold change with ECC in des −/− and wt, respectively: Mybph, 1.4 and 2.9; Xirp1, 2.2 and 5.7; Csrp3, 1.8 and 4.3), similar to the observed blunted mechanical response (torque drop: des −/− 30.3% and wt 55.5%). Interestingly, in the absence of stressors, des −/− muscle exhibited elevated expression of many these genes compared with wt. The largest transcriptional changes were observed in the interaction between aging and the absence of desmin, including many genes related to slow fiber pathway (Myh7, Myl3, Atp2a2, and Casq2) and insulin sensitivity (Tlr4, Trib3, Pdk3, and Pdk4). Consistent with these transcriptional changes, adult des −/− muscle exhibited a significant fiber type shift from fast to slow isoforms of myosin heavy chain ( wt, 5.3% IIa and 71.7% IIb; des −/−, 8.4% IIa and 61.4% IIb) and a decreased insulin-stimulated glucose uptake ( wt, 0.188 μmol/g muscle/20 min; des −/−, 0.085 μmol/g muscle/20 min). This work points to novel areas of influence of this cytoskeletal protein and directs future work to elucidate its function.

scholarly journals MRTF transcription and Ezrin-dependent plasma membrane blebbing are required for entotic invasion

2017 ◽  
Vol 216 (10) ◽  
pp. 3087-3095 ◽  
Author(s):  
Laura Soto Hinojosa ◽  
Manuel Holst ◽  
Christian Baarlink ◽  
Robert Grosse
Keyword(s):  
Plasma Membrane ◽  
Cell Invasion ◽  
Serum Response Factor ◽  
Critical Role ◽  
Actin Dynamics ◽  
Actin Cortex ◽  
Tightly Coupled ◽  
Related Transcription Factor ◽  
Nuclear Shuttling ◽  
The Impact

Entosis is a nonapoptotic form of cell death initiated by actomyosin-dependent homotypic cell-in-cell invasion that can be observed in malignant exudates during tumor progression. We previously demonstrated formin-mediated actin dynamics at the rear of the invading cell as well as nonapoptotic plasma membrane (PM) blebbing in this cellular motile process. Although the contractile actin cortex involved in bleb-driven motility is well characterized, a role for transcriptional regulation in this process has not been studied. Here, we explore the impact of the actin-controlled MRTF–SRF (myocardin-related transcription factor–serum response factor) pathway for sustained PM blebbing and entotic invasion. We find that cortical blebbing is tightly coupled to MRTF nuclear shuttling to promote the SRF transcriptional activity required for entosis. Furthermore, PM blebbing triggered SRF-mediated up-regulation of the metastasis-associated ERM protein Ezrin. Notably, Ezrin is sufficient and important to sustain bleb dynamics for cell-in-cell invasion when SRF is suppressed. Our results highlight the critical role of the actin-regulated MRTF transcriptional pathway for bleb-associated invasive motility, such as during entosis.

scholarly journals Transcriptional signatures throughout development: the effects of mouse embryo manipulation in vitro

Reproduction ◽  
2017 ◽  
Vol 153 (1) ◽  
pp. 107-122 ◽  
Author(s):  
Sky K Feuer ◽  
Xiaowei Liu ◽  
Annemarie Donjacour ◽  
Rhodel Simbulan ◽  
Emin Maltepe ◽  
...  
Keyword(s):  
Gene Expression ◽  
Molecular Mechanisms ◽  
Preimplantation Embryo ◽  
Environmental Exposures ◽  
Developmental Time ◽  
Transcriptional Responses ◽  
Transcriptional Changes ◽  
Specific Impact

Stressful environmental exposures incurred early in development can affect postnatal metabolic health and susceptibility to non-communicable diseases in adulthood, although the molecular mechanisms by which this occurs have yet to be elucidated. Here, we use a mouse model to investigate how assortedin vitroexposures restricted exclusively to the preimplantation period affect transcription both acutely in embryos and long term in subsequent offspring adult tissues, to determine if reliable transcriptional markers ofin vitrostress are present at specific developmental time points and throughout development. Eachin vitrofertilization or embryo culture environment led to a specific and unique blastocyst transcriptional profile, but we identified a common 18-gene and 9-pathway signature of preimplantation embryo manipulation that was present in allin vitroembryos irrespective of culture condition or method of fertilization. This fingerprint did not persist throughout development, and there was no clear transcriptional cohesion between adult IVF offspring tissues or compared to their preceding embryos, indicating a tissue-specific impact ofin vitrostress on gene expression. However, the transcriptional changes present in each IVF tissue were targeted by the same upstream transcriptional regulators, which provide insight as to how acute transcriptional responses to stressful environmental exposures might be preserved throughout development to influence adult gene expression.

scholarly journals In-vivo targeted tagging of RNA isolates cell specific transcriptional responses to environmental stimuli and identifies liver-to-adipose RNA transfer

2019 ◽  
Author(s):  
J. Darr ◽  
M. Lassi ◽  
Archana Tomar ◽  
R. Gerlini ◽  
F. Scheid ◽  
...  
Keyword(s):  
Transcriptional Response ◽  
Cellular Communication ◽  
Lipid Homeostasis ◽  
Tissue Architecture ◽  
Transcriptional Responses ◽  
Rna Transcripts ◽  
Novel Method ◽  
Endocrine Signaling

AbstractBio-fluids contain various circulating cell-free RNA transcripts (ccfRNAs). The composition of these ccfRNAs varies between bio-fluids and constitute tantalizing biomarker candidates for several pathologies. ccfRNAs have also been demonstrated as mediators of cellular communication, yet little is known about their function in physiological and developmental settings and most works are limited to in-vitro studies. Here, we have developed iTAG-RNA, a novel method for the unbiased tagging of RNA transcripts in mice in-vivo. We used this method to isolate hepatocytes and kidney proximal epithelial cells-specific transcriptional response to a dietary challenge without interfering with the tissue architecture, and to identify multiple hepatocyte-secreted ccfRNAs in plasma. We also identified transfer of these hepatic derived ccfRNAs to adipose tissue, where they likely serve as a buffering mechanism to maintain cholesterol and lipid homeostasis. Our findings directly demonstrate in-vivo transfer of RNAs between tissues and highlight its implications for endocrine signaling and homeostasis.

scholarly journals Interleukin-17A causes osteoarthritis-like transcriptional changes in human osteoarthritis-derived chondrocytes and synovial fibroblasts in vitro

2021 ◽  
Author(s):  
Jolet Y. Mimpen ◽  
Mathew J. Baldwin ◽  
Adam P. Cribbs ◽  
Martin Philpott ◽  
Andrew J. Carr ◽  
...  
Keyword(s):  
Gene Expression ◽  
Disease Gene ◽  
Therapeutic Option ◽  
Family Members ◽  
Transcriptional Response ◽  
Synovial Fibroblasts ◽  
Gene Sets ◽  
Transcriptional Changes ◽  
End Stage

AbstractIncreased interleukin (IL)-17A has been identified in joints affected by osteoarthritis (OA), but it is unclear how IL-17A, and its family members IL-17AF and IL-17F, can contribute to human OA pathophysiology. Therefore, we aimed to evaluate the gene expression and signalling pathway activation effects of the different IL-17 family members in fibroblasts derived from cartilage and synovium of patients with end-stage knee OA. Immunohistochemistry staining confirmed that IL-17 receptors A (IL-17RA) and IL-17RC are expressed in end-stage OA-derived cartilage and synovium. Chondrocytes and synovial fibroblasts derived from end-stage OA patients were treated with IL-17A, IL-17AF, or IL-17F, and gene expression was assessed with bulk RNA-Seq. Hallmark pathway analysis showed that IL-17 cytokines regulated several OA pathophysiology-related pathways including immune-, angiogenesis-, and complement-pathways in both chondrocytes and synovial fibroblasts derived from end-stage OA patients. While overall IL-17A induced the strongest transcriptional response, followed by IL-17AF and IL-17F, not all genes followed this pattern. Disease-Gene Network analysis revealed that IL-17A-related changes in gene expression in these cells are associated with experimental arthritis, knee arthritis, and musculoskeletal disease gene-sets. Western blot analysis confirmed that IL-17A significantly activates p38 and p65 NF-κB. Incubation of chondrocytes and synovial fibroblasts with IL-17A antibody secukinumab significantly inhibited IL-17A-induced gene expression. In conclusion, the association of IL-17-induced transcriptional changes with arthritic gene-sets supports a role for IL-17A in OA pathophysiology. Therefore, secukinumab could be investigated as a potential therapeutic option in OA patients.

scholarly journals Patterns of parent and offspring gene expression reflect canalization, not plasticity, in response to environmental stress

2021 ◽  
Author(s):  
Jeanette B Moss ◽  
Christopher B Cunningham ◽  
Elizabeth C McKinney ◽  
Allen J. Moore
Keyword(s):  
Gene Expression ◽  
Environmental Change ◽  
Environmental Stress ◽  
Behavioral Plasticity ◽  
Transcriptional Response ◽  
Transcriptional Responses ◽  
Behavioral Stability ◽  
The Face ◽  
Transcriptional Changes ◽  
Hostile Environments

Parenting buffers offspring from hostile environments, but it is not clear how or if the genes that underlie parenting change their expression under environmental stress. We recently demonstrated that for the subsocial carrion beetle, Nicrophorus orbicollis, temperature during parenting does not affect parenting phenotypes. Here, we ask if transcriptional changes associated with parenting are likewise robust to environmental stress. The absence of a transcriptional response for parenting under stress would suggest that the genetic programs for parenting and being parented are canalized. Conversely, a robust transcriptional response would suggest that plasticity of underlying gene expression is critical for maintaining behavioral stability, and that these mechanisms provide a potential target for selection in the face of environmental change. We test these alternatives by characterizing gene expression of parents and offspring with and without parent-offspring interactions under a benign and a stressful temperature. We found that parent-offspring interactions elicit distinct transcriptional responses of parents and larvae irrespective of temperature. We further detected robust changes of gene expression in beetles breeding at 24 degrees C compared to 20 degrees C irrespective of family interaction. However, no strong interaction between parent-offspring interaction and temperature was detected for either parents or larvae. We therefore conclude that canalization, not plasticity of gene expression, most likely explains the absence of behavioral plasticity under thermal stress. This result suggests that species may not have the genetic variation needed to respond to all environmental change, especially for complex phenotypes.

scholarly journals Lamina-associated polypeptide 2α is required for intranuclear MRTF-A activity

2021 ◽  
Author(s):  
Ekaterina Sidorenko ◽  
Maria Sokolova ◽  
Antti Pennanen ◽  
Salla Kyheroinen ◽  
Guido Posern ◽  
...  
Keyword(s):  
Target Genes ◽  
Serum Response Factor ◽  
Actin Dynamics ◽  
Chromatin Binding ◽  
Binding Partner ◽  
Related Transcription Factor ◽  
Direct Binding ◽  
Efficient Expression ◽  
Serum Response

Myocardin-related transcription factor A (MRTF-A), a coactivator of serum response factor (SRF), regulates the expression of many cytoskeletal genes in response to cytoplasmic and nuclear actin dynamics. Here we describe a novel mechanism to regulate MRTF-A activity within the nucleus by showing that lamina-associated polypeptide 2α (Lap2α), the nucleoplasmic isoform of Lap2, is a direct binding partner of MRTF-A, and required for the efficient expression of MRTF-A/SRF target genes. Mechanistically, Lap2α is not required for MRTF-A nuclear localization, unlike most other MRTF-A regulators, but is required for binding of MRTF-A to its target genes. This regulatory step takes place prior to MRTF-A chromatin binding, because Lap2α neither interacts with, nor specifically influences active histone marks on MRTF-A/SRF target genes. Phenotypically, Lap2α is required for serum-induced cell migration, and deregulated MRTF-A activity may also contribute to muscle and proliferation phenotypes associated with loss of Lap2α. Our studies therefore add another regulatory layer to the control of MRTF-A-SRF-mediated gene expression, and broaden the role of Lap2α in transcriptional regulation.

scholarly journals MON-727 The Chromatin Landscape of Glucocorticoid Regulated Genes in Mouse Embryonic Neural Stem / Progenitor Cells

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Kimberly Berry ◽  
Uma Chandran ◽  
Fangping Mu ◽  
Donald DeFranco
Keyword(s):  
Progenitor Cells ◽  
Target Genes ◽  
Therapeutic Potential ◽  
Transcriptional Response ◽  
Clinical Intervention ◽  
Enrichment Analysis ◽  
Open Chromatin ◽  
Transcriptional Responses ◽  
Embryonic Mouse

Abstract Stem/Progenitor Cells Antenatal administration of Dexamethasone (Dex), a synthetic glucocorticoid (GC), is a common clinical intervention for women at risk for preterm birth or in preterm labor that effectively reduces fetal risk of mortality and bronchopulmonary-related comorbidities. Despite the therapeutic potential of Dex, excess GC act adversely in the developing central nervous system to reprogram distinct neural circuits in the brain by acting through the glucocorticoid receptor (GR). For example, prenatal exposure to excess GCs can impact neural stem and progenitor cell (NSPC) proliferation leading to long-term alterations in prefrontal cortical neuronal complexity, which could contribute to behavioral and cognitive impairments later in life. The GR is a member of the nuclear receptor superfamily that, when bound by a ligand, translocates from the cytoplasm to the nucleus and associates indirectly or directly with DNA elements (e.g. glucocorticoid responsive elements or GREs) resulting in the activation and/or repression of target genes. While GR-regulated transcriptomes have been identified in many NSPC models, the mechanisms responsible for programming these cells for GC-responsiveness remain largely unknown. We therefore used transposase accessible chromatin followed by genome-wide sequencing (Omni ATAC-seq) to characterize the chromatin landscape of primary embryonic mouse NSPCs in response to an acute in vitro treatment with Dex. We identified a small, yet distinct fraction (0.002%, p<0.05) of open chromatin sites that were Dex-inducible. 95% of these Dex-induced changes in chromatin accessibility occur within intronic or intergenic regions, suggesting the presence of long-range enhancer-promoter contacts that mediate NSPC transcriptional responses to Dex. Motif enrichment analysis revealed putative GRE sites located in Dex-inducible open chromatin within -5kb/+2kb of a Dex-induced gene, providing possible DNA targets of GR for further validation. A number of other transcription factors implicated in neurodevelopmental processes were found to underlie both Dex-inducible and constitutively open chromatin regions. Characterization of the precise epigenetic and transcriptional response to excess GC in-utero, and its influence on acute and chronic neurological outcomes, will encourage the development of alternative GC treatment regimens that could protect the developing brain from insult while providing optimal health outcomes in neonates.

scholarly journals Glucose and glutamine availability regulate HepG2 transcriptional responses to low oxygen

2018 ◽  
Vol 3 ◽  
pp. 126 ◽  
Author(s):  
Alvina G. Lai ◽  
Donall Forde ◽  
Wai Hoong Chang ◽  
Fang Yuan ◽  
Xiaodong Zhuang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mass Spectrometry ◽  
Transcriptional Response ◽  
Global Changes ◽  
Low Oxygen ◽  
Transcriptional Responses ◽  
Dna Hydroxymethylation ◽  
Modified Dna ◽  
The Impact

Background: Little is known about the impact of nutrients on cellular transcriptional responses, especially in face of environmental stressors such as oxygen deprivation. Hypoxia-inducible factors (HIF) coordinate the expression of genes essential for adaptation to oxygen-deprived environments. A second family of oxygen-sensing genes known as the alpha-ketoglutarate-dependent dioxygenases are also implicated in oxygen homeostasis and epigenetic regulation. The relationship between nutritional status and cellular response to hypoxia is understudied. In vitro cell culture systems frequently propagate cells in media that contains excess nutrients, and this may directly influence transcriptional response in hypoxia. Methods: We studied the effect of glucose and glutamine concentration on HepG2 hepatoma transcriptional response to low oxygen and expression of hypoxia inducible factor-1α (HIF-1α). Mass spectrometry confirmed low oxygen perturbation of dioxygenase transcripts resulted in changes in DNA methylation. Results: Under normoxic conditions, we observed a significant upregulation of both HIF-target genes and oxygen-dependent dioxygenases in HepG2 cells cultured with physiological levels of glucose or glutamine relative to regular DMEM media, demonstrating that excess glutamine/glucose can mask changes in gene expression. Under hypoxic conditions, CA9 was the most upregulated gene in physiological glutamine media while TETs and FTO dioxygenases were downregulated in physiological glucose. Hypoxic regulation of these transcripts did not associate with changes in HIF-1α protein expression. Downregulation of TETs suggests a potential for epigenetic modulation. Mass-spectrometry quantification of modified DNA bases confirmed our transcript data. Hypoxia resulted in decreased DNA hydroxymethylation, which correlated with TETs downregulation. Additionally, we observed that TET2 expression was significantly downregulated in patients with hepatocellular carcinoma, suggesting that tumour hypoxia may deregulate TET2 expression resulting in global changes in DNA hydroxymethylation.   Conclusion: Given the dramatic effects of nutrient availability on gene expression, future in vitro experiments should be aware of how excess levels of glutamine and glucose may perturb transcriptional responses.

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