The Broad Transcription Factor Links Hormonal Signaling, Gene Expression, and Cellular Morphogenesis Events During Drosophila Imaginal Disc Development

Imaginal disc morphogenesis during metamorphosis in Drosophila melanogaster provides an excellent model to uncover molecular mechanisms by which hormonal signals effect physical changes during development. The broad (br) Z2 isoform encodes a transcription factor required for disc morphogenesis in response to 20-hydroxyecdysone, yet how it accomplishes this remains largely unknown. Here, we use functional studies of amorphic br5 mutants and a transcriptional target approach to identify processes driven by br and its regulatory targets in leg imaginal discs. br5 mutants fail to properly remodel their basal extracellular matrix (ECM) between 4 and 7 hr after puparium formation. Additionally, br5 mutant discs do not undergo the cell shape changes necessary for leg elongation and fail to elongate normally when exposed to the protease trypsin. RNA-sequencing of wild-type and br5 mutant leg discs identified 717 genes differentially regulated by br, including a large number of genes involved in glycolysis, and genes that encode proteins that interact with the ECM. RNA interference-based functional studies reveal that several of these genes are required for adult leg formation, particularly those involved in remodeling the ECM. Additionally, br Z2 expression is abruptly shut down at the onset of metamorphosis, and expressing it beyond this time results in failure of leg development during the late prepupal and pupal stages. Taken together, our results suggest that br Z2 is required to drive ECM remodeling, change cell shape, and maintain metabolic activity through the midprepupal stage, but must be switched off to allow expression of pupation genes.

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broad controls leg imaginal disc morphogenesis in Drosophila via regulation of cell shape changes and remodeling of extracellular matrix

10.1101/2019.12.21.885848 ◽

2019 ◽

Author(s):

Clinton Rice ◽

Stuart Macdonald ◽

Xiaochen Wang ◽

Robert E Ward

Keyword(s):

Extracellular Matrix ◽

Transcription Factor ◽

Drosophila Melanogaster ◽

Cell Shape ◽

Imaginal Disc ◽

Molecular Mechanisms ◽

Matrix Remodeling ◽

Ecm Remodeling ◽

Cell Shape Changes ◽

Shape Changes

AbstractImaginal disc morphogenesis during metamorphosis in Drosophila melanogaster provides an excellent model to uncover molecular mechanisms by which hormonal signals effect physical changes during development. The broad (br) Z2 isoform encodes a transcription factor required for disc morphogenesis in response to 20-hydroxyecdysone, yet how it accomplishes this remains largely unknown. Here, we show that amorphic br5 mutant discs fail to remodel their basal extracellular matrix (ECM) after puparium formation and do not undergo necessary cell shape changes. RNA sequencing of wild type and mutant leg discs identified 717 genes differentially regulated by br; functional studies reveal that several are required for adult leg formation, particularly those involved in remodeling the ECM. Additionally, br Z2 expression is abruptly shut down at the onset of metamorphosis, and expressing it beyond this time results in failure of leg development during the late prepupal and pupal stages. Taken together, our results suggest that br Z2 is required to drive ECM remodeling, change cell shape, and maintain metabolic activity through the mid prepupal stage, but must be switched off to allow expression of pupation genes.Summary StatementThe Drosophila melanogaster ecdysone-responding transcription factor broad controls morphogenetic processes in leg imaginal discs during metamorphosis through regulation of genes involved in extracellular matrix remodeling, metabolism, and cell shape changes and rearrangements.

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Leg development in flies versus grasshoppers: differences in dpp expression do not lead to differences in the expression of downstream components of the leg patterning pathway

Development ◽

10.1242/dev.127.8.1617 ◽

2000 ◽

Vol 127 (8) ◽

pp. 1617-1626 ◽

Cited By ~ 2

Author(s):

E.L. Jockusch ◽

C. Nulsen ◽

S.J. Newfeld ◽

L.M. Nagy

Keyword(s):

Imaginal Disc ◽

Body Wall ◽

Molecular Mechanisms ◽

Current Model ◽

The Body ◽

Genetic Interactions ◽

Leg Development ◽

Evolutionarily Conserved ◽

Early Expression ◽

Two Phases

All insect legs are structurally similar, characterized by five primary segments. However, this final form is achieved in different ways. Primitively, the legs developed as direct outgrowths of the body wall, a condition retained in most insect species. In some groups, including the lineage containing the genus Drosophila, legs develop indirectly from imaginal discs. Our understanding of the molecular mechanisms regulating leg development is based largely on analysis of this derived mode of leg development in the species D. melanogaster. The current model for Drosophila leg development is divided into two phases, embryonic allocation and imaginal disc patterning, which are distinguished by interactions among the genes wingless (wg), decapentaplegic (dpp) and distalless (dll). In the allocation phase, dll is activated by wg but repressed by dpp. During imaginal disc patterning, dpp and wg cooperatively activate dll and also indirectly inhibit the nuclear localization of Extradenticle (Exd), which divide the leg into distal and proximal domains. In the grasshopper Schistocerca americana, the early expression pattern of dpp differs radically from the Drosophila pattern, suggesting that the genetic interactions that allocate the leg differ between the two species. Despite early differences in dpp expression, wg, Dll and Exd are expressed in similar patterns throughout the development of grasshopper and fly legs, suggesting that some aspects of proximodistal (P/D) patterning are evolutionarily conserved. We also detect differences in later dpp expression, which suggests that dpp likely plays a role in limb segmentation in Schistocerca, but not in Drosophila. The divergence in dpp expression is surprising given that all other comparative data on gene expression during insect leg development indicate that the molecular pathways regulating this process are conserved. However, it is consistent with the early divergence in developmental mode between fly and grasshopper limbs.

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Transcription factor/DNA interactions visualized by electron spectroscopic imaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122654 ◽

1992 ◽

Vol 50 (1) ◽

pp. 450-451

Author(s):

David P. Bazett-Jones ◽

Mark L. Brown

Keyword(s):

Transcription Factor ◽

Dna Sequences ◽

Transcription Initiation ◽

Molecular Mechanisms ◽

Phosphorus Content ◽

Spectroscopic Imaging ◽

Electron Spectroscopic Imaging ◽

Dna Backbone ◽

Two Parameters ◽

High Level

A multisubunit RNA polymerase enzyme is ultimately responsible for transcription initiation and elongation of RNA, but recognition of the proper start site by the enzyme is regulated by general, temporal and gene-specific trans-factors interacting at promoter and enhancer DNA sequences. To understand the molecular mechanisms which precisely regulate the transcription initiation event, it is crucial to elucidate the structure of the transcription factor/DNA complexes involved. Electron spectroscopic imaging (ESI) provides the opportunity to visualize individual DNA molecules. Enhancement of DNA contrast with ESI is accomplished by imaging with electrons that have interacted with inner shell electrons of phosphorus in the DNA backbone. Phosphorus detection at this intermediately high level of resolution (≈lnm) permits selective imaging of the DNA, to determine whether the protein factors compact, bend or wrap the DNA. Simultaneously, mass analysis and phosphorus content can be measured quantitatively, using adjacent DNA or tobacco mosaic virus (TMV) as mass and phosphorus standards. These two parameters provide stoichiometric information relating the ratios of protein:DNA content.

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Molecular regulation of Snai2 in development and disease

Journal of Cell Science ◽

10.1242/jcs.235127 ◽

2019 ◽

Vol 132 (23) ◽

Author(s):

Wenhui Zhou ◽

Kayla M. Gross ◽

Charlotte Kuperwasser

Keyword(s):

Transcription Factor ◽

Cell Biology ◽

Molecular Mechanisms ◽

Epithelial To Mesenchymal Transition ◽

Zinc Finger Protein ◽

Main Role ◽

Biological Processes ◽

Developmental Defects ◽

Mesenchymal Transition ◽

Damage Repair

ABSTRACT The transcription factor Snai2, encoded by the SNAI2 gene, is an evolutionarily conserved C2H2 zinc finger protein that orchestrates biological processes critical to tissue development and tumorigenesis. Initially characterized as a prototypical epithelial-to-mesenchymal transition (EMT) transcription factor, Snai2 has been shown more recently to participate in a wider variety of biological processes, including tumor metastasis, stem and/or progenitor cell biology, cellular differentiation, vascular remodeling and DNA damage repair. The main role of Snai2 in controlling such processes involves facilitating the epigenetic regulation of transcriptional programs, and, as such, its dysregulation manifests in developmental defects, disruption of tissue homeostasis, and other disease conditions. Here, we discuss our current understanding of the molecular mechanisms regulating Snai2 expression, abundance and activity. In addition, we outline how these mechanisms contribute to disease phenotypes or how they may impact rational therapeutic targeting of Snai2 dysregulation in human disease.

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The AP-1 Transcription Factor Fosl-2 Regulates Autophagy in Cardiac Fibroblasts during Myocardial Fibrogenesis

International Journal of Molecular Sciences ◽

10.3390/ijms22041861 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1861

Author(s):

Jemima Seidenberg ◽

Mara Stellato ◽

Amela Hukara ◽

Burkhard Ludewig ◽

Karin Klingel ◽

...

Keyword(s):

Transcription Factor ◽

Molecular Mechanisms ◽

Cardiac Fibrosis ◽

Type I Collagen ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Smooth Muscle Actin ◽

Beclin 1 ◽

Type I ◽

Alpha Smooth Muscle Actin

Background: Pathological activation of cardiac fibroblasts is a key step in development and progression of cardiac fibrosis and heart failure. This process has been associated with enhanced autophagocytosis, but molecular mechanisms remain largely unknown. Methods and Results: Immunohistochemical analysis of endomyocardial biopsies showed increased activation of autophagy in fibrotic hearts of patients with inflammatory cardiomyopathy. In vitro experiments using mouse and human cardiac fibroblasts confirmed that blockade of autophagy with Bafilomycin A1 inhibited fibroblast-to-myofibroblast transition induced by transforming growth factor (TGF)-β. Next, we observed that cardiac fibroblasts obtained from mice overexpressing transcription factor Fos-related antigen 2 (Fosl-2tg) expressed elevated protein levels of autophagy markers: the lipid modified form of microtubule-associated protein 1A/1B-light chain 3B (LC3BII), Beclin-1 and autophagy related 5 (Atg5). In complementary experiments, silencing of Fosl-2 with antisense GapmeR oligonucleotides suppressed production of type I collagen, myofibroblast marker alpha smooth muscle actin and autophagy marker Beclin-1 in cardiac fibroblasts. On the other hand, silencing of either LC3B or Beclin-1 reduced Fosl-2 levels in TGF-β-activated, but not in unstimulated cells. Using a cardiac hypertrophy model induced by continuous infusion of angiotensin II with osmotic minipumps, we confirmed that mice lacking either Fosl-2 (Ccl19CreFosl2flox/flox) or Atg5 (Ccl19CreAtg5flox/flox) in stromal cells were protected from cardiac fibrosis. Conclusion: Our findings demonstrate that Fosl-2 regulates autophagocytosis and the TGF-β-Fosl-2-autophagy axis controls differentiation of cardiac fibroblasts. These data provide a new insight for the development of pharmaceutical targets in cardiac fibrosis.

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The apple C2H2-type zinc finger transcription factor MdZAT10 positively regulates JA-induced leaf senescence by interacting with MdBT2

Horticulture Research ◽

10.1038/s41438-021-00593-0 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Kuo Yang ◽

Jian-Ping An ◽

Chong-Yang Li ◽

Xue-Na Shen ◽

Ya-Jing Liu ◽

...

Keyword(s):

Mass Spectrometry ◽

Transcription Factor ◽

Liquid Chromatography ◽

Zinc Finger ◽

Leaf Senescence ◽

Transcriptional Activity ◽

Molecular Mechanisms ◽

Liquid Chromatography Mass Spectrometry ◽

Zinc Finger Transcription Factor ◽

Insight Into

AbstractJasmonic acid (JA) plays an important role in regulating leaf senescence. However, the molecular mechanisms of leaf senescence in apple (Malus domestica) remain elusive. In this study, we found that MdZAT10, a C2H2-type zinc finger transcription factor (TF) in apple, markedly accelerates leaf senescence and increases the expression of senescence-related genes. To explore how MdZAT10 promotes leaf senescence, we carried out liquid chromatography/mass spectrometry screening. We found that MdABI5 physically interacts with MdZAT10. MdABI5, an important positive regulator of leaf senescence, significantly accelerated leaf senescence in apple. MdZAT10 was found to enhance the transcriptional activity of MdABI5 for MdNYC1 and MdNYE1, thus accelerating leaf senescence. In addition, we found that MdZAT10 expression was induced by methyl jasmonate (MeJA), which accelerated JA-induced leaf senescence. We also found that the JA-responsive protein MdBT2 directly interacts with MdZAT10 and reduces its protein stability through ubiquitination and degradation, thereby delaying MdZAT10-mediated leaf senescence. Taken together, our results provide new insight into the mechanisms by which MdZAT10 positively regulates JA-induced leaf senescence in apple.

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Regulatory Role of microRNAs Targeting the Transcription Co-Factor ZNF521 in Normal Tissues and Cancers

International Journal of Molecular Sciences ◽

10.3390/ijms22168461 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8461

Author(s):

Emanuela Chiarella ◽

Annamaria Aloisio ◽

Stefania Scicchitano ◽

Heather Mandy Bond ◽

Maria Mesuraca

Keyword(s):

Transcription Factor ◽

Molecular Mechanisms ◽

Transitional Cell ◽

Biological Functions ◽

Aberrant Expression ◽

Normal Tissues ◽

Novel Mirna ◽

Mirna Expression Profiling ◽

Mirna Deregulation

Powerful bioinformatics tools have provided a wealth of novel miRNA–transcription factor networks crucial in controlling gene regulation. In this review, we focus on the biological functions of miRNAs targeting ZNF521, explaining the molecular mechanisms by which the dysregulation of this axis contributes to malignancy. ZNF521 is a stem cell-associated co-transcription factor implicated in the regulation of hematopoietic, neural, and mesenchymal stem cells. The aberrant expression of ZNF521 transcripts, frequently associated with miRNA deregulation, has been detected in several tumors including pancreatic, hepatocellular, gastric, bladder transitional cell carcinomas as well as in breast and ovarian cancers. miRNA expression profiling tools are currently identifying a multitude of miRNAs, involved together with oncogenes and TFs in the regulation of oncogenesis, including ZNF521, which may be candidates for diagnostic and prognostic biomarkers of cancer.

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Tracing the origins of SARS-COV-2 in coronavirus phylogenies: a review

Environmental Chemistry Letters ◽

10.1007/s10311-020-01151-1 ◽

2021 ◽

Vol 19 (2) ◽

pp. 769-785 ◽

Cited By ~ 1

Author(s):

Erwan Sallard ◽

José Halloy ◽

Didier Casane ◽

Etienne Decroly ◽

Jacques van Helden

Keyword(s):

Sequence Analysis ◽

Structure Function ◽

Molecular Mechanisms ◽

Laboratory Strain ◽

Domestic Animals ◽

Scientific Policy ◽

Human Coronavirus ◽

Viral Dissemination ◽

Link Type ◽

Intensive Breeding

AbstractSARS-CoV-2 is a new human coronavirus (CoV), which emerged in China in late 2019 and is responsible for the global COVID-19 pandemic that caused more than 97 million infections and 2 million deaths in 12 months. Understanding the origin of this virus is an important issue, and it is necessary to determine the mechanisms of viral dissemination in order to contain future epidemics. Based on phylogenetic inferences, sequence analysis and structure–function relationships of coronavirus proteins, informed by the knowledge currently available on the virus, we discuss the different scenarios on the origin—natural or synthetic—of the virus. The data currently available are not sufficient to firmly assert whether SARS-CoV2 results from a zoonotic emergence or from an accidental escape of a laboratory strain. This question needs to be solved because it has important consequences on the risk/benefit balance of our interactions with ecosystems, on intensive breeding of wild and domestic animals, on some laboratory practices and on scientific policy and biosafety regulations. Regardless of COVID-19 origin, studying the evolution of the molecular mechanisms involved in the emergence of pandemic viruses is essential to develop therapeutic and vaccine strategies and to prevent future zoonoses. This article is a translation and update of a French article published in Médecine/Sciences, August/September 2020 (10.1051/medsci/2020123).

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EspM Is a Conserved Transcription Factor That Regulates Gene Expression in Response to the ESX-1 System

mBio ◽

10.1128/mbio.02807-19 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 3

Author(s):

Kevin G. Sanchez ◽

Micah J. Ferrell ◽

Alexandra E. Chirakos ◽

Kathleen R. Nicholson ◽

Robert B. Abramovitch ◽

...

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Protein Transport ◽

Transcriptional Response ◽

Secretion System ◽

Pathogenic Species ◽

Macrophage Infection ◽

Content Type ◽

Link Type ◽

Phagosomal Membrane

ABSTRACT Pathogenic mycobacteria encounter multiple environments during macrophage infection. Temporally, the bacteria are engulfed into the phagosome, lyse the phagosomal membrane, and interact with the cytosol before spreading to another cell. Virulence factors secreted by the mycobacterial ESX-1 (ESAT-6-system-1) secretion system mediate the essential transition from the phagosome to the cytosol. It was recently discovered that the ESX-1 system also regulates mycobacterial gene expression in Mycobacterium marinum (R. E. Bosserman, T. T. Nguyen, K. G. Sanchez, A. E. Chirakos, et al., Proc Natl Acad Sci U S A 114:E10772–E10781, 2017, https://doi.org/10.1073/pnas.1710167114), a nontuberculous mycobacterial pathogen, and in the human-pathogenic species M. tuberculosis (A. M. Abdallah, E. M. Weerdenburg, Q. Guan, R. Ummels, et al., PLoS One 14:e0211003, 2019, https://doi.org/10.1371/journal.pone.0211003). It is not known how the ESX-1 system regulates gene expression. Here, we identify the first transcription factor required for the ESX-1-dependent transcriptional response in pathogenic mycobacteria. We demonstrate that the gene divergently transcribed from the whiB6 gene and adjacent to the ESX-1 locus in mycobacterial pathogens encodes a conserved transcription factor (MMAR_5438, Rv3863, now espM). We prove that EspM from both M. marinum and M. tuberculosis directly and specifically binds the whiB6-espM intergenic region. We show that EspM is required for ESX-1-dependent repression of whiB6 expression and for the regulation of ESX-1-associated gene expression. Finally, we demonstrate that EspM functions to fine-tune ESX-1 activity in M. marinum. Taking the data together, this report extends the esx-1 locus, defines a conserved regulator of the ESX-1 virulence pathway, and begins to elucidate how the ESX-1 system regulates gene expression. IMPORTANCE Mycobacterial pathogens use the ESX-1 system to transport protein substrates that mediate essential interactions with the host during infection. We previously demonstrated that in addition to transporting proteins, the ESX-1 secretion system regulates gene expression. Here, we identify a conserved transcription factor that regulates gene expression in response to the ESX-1 system. We demonstrate that this transcription factor is functionally conserved in M. marinum, a pathogen of ectothermic animals; M. tuberculosis, the human-pathogenic species that causes tuberculosis; and M. smegmatis, a nonpathogenic mycobacterial species. These findings provide the first mechanistic insight into how the ESX-1 system elicits a transcriptional response, a function of this protein transport system that was previously unknown.

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Endothelin 1-induced retinal ganglion cell death is largely mediated by JUN activation

Cell Death and Disease ◽

10.1038/s41419-020-02990-0 ◽

2020 ◽

Vol 11 (9) ◽

Author(s):

Olivia J. Marola ◽

Stephanie B. Syc-Mazurek ◽

Gareth R. Howell ◽

Richard T. Libby

Keyword(s):

Transcription Factor ◽

Molecular Mechanisms ◽

Ganglion Cells ◽

Retinal Vessel ◽

Vessel Diameter ◽

Retinal Ganglion ◽

Retinal Ganglion Cell Death ◽

Ganglion Cell Death

Abstract Glaucoma is a neurodegenerative disease characterized by loss of retinal ganglion cells (RGCs), the output neurons of the retina. Multiple lines of evidence show the endothelin (EDN, also known as ET) system is important in glaucomatous neurodegeneration. To date, the molecular mechanisms within RGCs driving EDN-induced RGC death have not been clarified. The pro-apoptotic transcription factor JUN (the canonical target of JNK signaling) and the endoplasmic reticulum stress effector and transcription factor DNA damage inducible transcript 3 (DDIT3, also known as CHOP) have been shown to act downstream of EDN receptors. Previous studies demonstrated that JUN and DDIT3 were important regulators of RGC death after glaucoma-relevant injures. Here, we characterized EDN insult in vivo and investigated the role of JUN and DDIT3 in EDN-induced RGC death. To accomplish this, EDN1 ligand was intravitreally injected into the eyes of wildtype, Six3-cre+Junfl/fl (Jun−/−), Ddit3 null (Ddit3−/−), and Ddit3−/−Jun−/− mice. Intravitreal EDN1 was sufficient to drive RGC death in vivo. EDN1 insult caused JUN activation in RGCs, and deletion of Jun from the neural retina attenuated RGC death after EDN insult. However, deletion of Ddit3 did not confer significant protection to RGCs after EDN1 insult. These results indicate that EDN caused RGC death via a JUN-dependent mechanism. In addition, EDN signaling is known to elicit potent vasoconstriction. JUN signaling was shown to drive neuronal death after ischemic insult. Therefore, the effects of intravitreal EDN1 on retinal vessel diameter and hypoxia were explored. Intravitreal EDN1 caused transient retinal vasoconstriction and regions of RGC and Müller glia hypoxia. Thus, it remains a possibility that EDN elicits a hypoxic insult to RGCs, causing apoptosis via JNK-JUN signaling. The importance of EDN-induced vasoconstriction and hypoxia in causing RGC death after EDN insult and in models of glaucoma requires further investigation.

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