Fli1 Promotes Vascular Morphogenesis by Regulating Endothelial Potential of Multipotent Myogenic Progenitors

Rationale: Fetal growth and survival depend critically on proper development and integrity of the vascular system. Fli1 (Friend leukemia integration 1), a member of the Ets family of transcription factors, plays critical roles in vascular morphogenesis and homeostasis at mid-gestation, the developmental stage at which expression of its upstream regulator, Etv2, ceases. However, molecular mechanisms of Fli1 action in vascular morphogenesis remain incompletely understood. Objective: To dissect molecular mechanisms of vascular morphogenesis governed by Fli1. Methods and Results: Utilizing Fli1 promoter-driven lineage-specific LacZ expression, Fli1 loss-of-function strategies, and a series of molecular techniques, we demonstrate that Fli1 expression in multipotent myogenic progenitor cells (MPCs) occurs independent of Etv2, and loss of Fli1 expression results in a significant increase in LacZ+ cells in mesoderm within somites and limb buds, leading to reciprocal regulation of the expression of several key endothelial and myogenic genes and vascular abnormalities. Conversely, embryos with conditional Fli1 gain-of-function in MPCs manifested aberrant vasculogenesis with lack of myogenesis. Mechanistically, elevated Fli1 activity in myoblasts and in adult MPCs (also called satellite cells) of X-linked muscular dystrophic mdx mice markedly induced endothelial, but attenuated myogenic, gene expression and differentiation. Importantly, ectopic expression of Myf5 or MyoD, two key myogenic regulators, in Fli1-expressing myoblasts restored their differentiation potential, indicating that levels of Fli1 and myogenic regulators in MPCs inversely regulate their endothelial versus myogenic potential. Conclusions: Fli1 governs vascular morphogenesis by regulating endothelial potential by inversely regulating endothelial versus myogenic programs in MPCs. Our data uncover an important and previously unrecognized mechanism of vascular morphogenesis governed by Fli1 and highlight the physiological significance of the fine tuning of Fli1 activity in multipotent progenitors for proper vascular and muscle morphogenesis during development and disease.

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Crosstalk of CREB and Fos/Jun on a single cis-element: transcriptional repression of the steroidogenic acute regulatory protein gene

Journal of Molecular Endocrinology ◽

10.1677/jme-07-0065 ◽

2007 ◽

Vol 39 (4) ◽

pp. 261-277 ◽

Cited By ~ 56

Author(s):

Pulak R Manna ◽

Douglas M Stocco

Keyword(s):

Transcriptional Repression ◽

Protein Gene ◽

Binding Protein ◽

Regulatory Protein ◽

Ectopic Expression ◽

Fine Tuning ◽

Creb Binding Protein ◽

Loss Of Function ◽

Cis Element ◽

Steroidogenic Acute Regulatory

AbstractTranscriptional regulation of the steroidogenic acute regulatory (StAR) protein gene by cAMP-dependent mechanisms occurs in the absence of a consensus cAMP-response element (CRE; TGACGTCA) and is mediated by several sequence-specific transcription factors. We previously identified three CRE-like sites (within the −151/−1 bp cAMP-responsive region of the mouse StAR gene), of which the CRE2 site overlaps with an activator protein-1 (AP-1) motif (TGACTGA, designated as CRE2/AP-1) that can bind both CRE and AP-1 DNA-binding proteins. The present studies were aimed at exploring the functional crosstalk between CREB (CRE-binding protein) and cFos/cJun (AP-1 family members) on the CRE2/AP-1 element and its role in regulating transcription of the StAR gene. Using MA-10 mouse Leydig tumor cells, we demonstrate that the CRE and AP-1 families of proteins interact with the CRE2/AP-1 sequence. CREB, cFos, and cJun proteins were found to bind to the CRE2/AP-1 motif but not the CRE1 and CRE3 sites. Treatment with the cAMP analog (Bu)2cAMP augmented phosphorylation of CREB (Ser133), cFos (Thr325), and cJun (ser73). Chromatin immunoprecipitation studies revealed that the induction of CREB, cFos, and cJun by (Bu)2cAMP was correlated with protein–DNA interactions and recruitment of the coactivator CREB-binding protein (CBP) to the StAR promoter. EMSA studies employing CREB and cFos/cJun proteins demonstrated competition between these factors for binding to the CRE2/AP-1 motif. Transfection of cells containing the −151/−1 StAR reporter with CREB and cFos/cJun resulted in trans-repression of the StAR gene, an event tightly associated with CBP, demonstrating that both CREB and Fos/Jun compete with each other for binding with limited amounts of intracellular CBP. Overexpression of adenovirus E1A, which binds and inactivates CBP, markedly suppressed StAR gene expression. Ectopic expression of CBP eliminated the repression of the StAR gene by E1A and potentiated the activity of CREB and cFos/cJun on StAR promoter responsiveness. These findings identify molecular events involved in crosstalk between CREB and cFos/cJun, which confer both gain and loss of function on a single cis-element in fine-tuning of the regulatory events involved in transcription of the StAR gene.

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bHLH11 negatively regulates Fe homeostasis by its EAR motifs recruiting corepressors in Arabidopsis

10.1101/2020.04.09.035097 ◽

2020 ◽

Author(s):

Yang Li ◽

Rihua Lei ◽

Mengna Pu ◽

Yuerong Cai ◽

Chengkai Lu ◽

...

Keyword(s):

Molecular Mechanisms ◽

Signal Sequence ◽

Negative Regulator ◽

Fine Tuning ◽

Nuclear Accumulation ◽

Loss Of Function ◽

Enhanced Sensitivity ◽

Crucial Component ◽

Regulation Function ◽

Fe Homeostasis

ABSTRACTIron (Fe) homeostasis is essential for plant growth and development. Although tremendous progress has been made in understanding the maintenance of Fe homeostasis in plants, the underlying molecular mechanisms remain elusive. Recently, bHLH11 was reported to function as a negative regulator. However, the molecular mechanism by which bHLH11 regulates Fe homeostasis is unclear. Here, we generated two bhlh11 loss-of-function mutants which displayed the enhanced sensitivity to excessive Fe. bHLH11 is located in the cytoplasm and nucleus due to lack of a nuclear location signal sequence, and its interaction partners, bHLH IVc transcription factors (TFs) (bHLH34, bHLH104, bHLH105 and bHLH115) facilitate its nuclear accumulation. bHLH11 exerts its negative regulation function by recruiting the corepressors TOPLESS/TOPLESS-RELATED. Moreover, bHLH11 antagonizes the transactivity of bHLH IVc TFs towards bHLH Ib genes (bHLH38, bHLH39, bHLH100 and bHLH101). This work indicates that bHLH11 is a crucial component of Fe homeostasis signaling network, playing a pivotal role in the fine-tuning of Fe homeostasis.

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An auxin signaling network translates low-sugar-state input into compensated cell enlargement in the fugu5 cotyledon

PLoS Genetics ◽

10.1371/journal.pgen.1009674 ◽

2021 ◽

Vol 17 (8) ◽

pp. e1009674

Author(s):

Hiromitsu Tabeta ◽

Shunsuke Watanabe ◽

Keita Fukuda ◽

Shizuka Gunji ◽

Mariko Asaoka ◽

...

Keyword(s):

Atpase Activity ◽

Molecular Mechanisms ◽

Genetic Interaction ◽

Mitotic Cell ◽

Fine Tuning ◽

Auxin Signaling ◽

Cell Enlargement ◽

Loss Of Function ◽

Nutrient Reserves

In plants, the effective mobilization of seed nutrient reserves is crucial during germination and for seedling establishment. The Arabidopsis H+-PPase-loss-of-function fugu5 mutants exhibit a reduced number of cells in the cotyledons. This leads to enhanced post-mitotic cell expansion, also known as compensated cell enlargement (CCE). While decreased cell numbers have been ascribed to reduced gluconeogenesis from triacylglycerol, the molecular mechanisms underlying CCE remain ill-known. Given the role of indole 3-butyric acid (IBA) in cotyledon development, and because CCE in fugu5 is specifically and completely cancelled by ech2, which shows defective IBA-to-indoleacetic acid (IAA) conversion, IBA has emerged as a potential regulator of CCE. Here, to further illuminate the regulatory role of IBA in CCE, we used a series of high-order mutants that harbored a specific defect in IBA-to-IAA conversion, IBA efflux, IAA signaling, or vacuolar type H+-ATPase (V-ATPase) activity and analyzed the genetic interaction with fugu5–1. We found that while CCE in fugu5 was promoted by IBA, defects in IBA-to-IAA conversion, IAA response, or the V-ATPase activity alone cancelled CCE. Consistently, endogenous IAA in fugu5 reached a level 2.2-fold higher than the WT in 1-week-old seedlings. Finally, the above findings were validated in icl–2, mls–2, pck1–2 and ibr10 mutants, in which CCE was triggered by low sugar contents. This provides a scenario in which following seed germination, the low-sugar-state triggers IAA synthesis, leading to CCE through the activation of the V-ATPase. These findings illustrate how fine-tuning cell and organ size regulation depend on interplays between metabolism and IAA levels in plants.

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Myxoma virus M156 is a specific inhibitor of rabbit PKR but contains a loss-of-function mutation in Australian virus isolates

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1515613113 ◽

2016 ◽

Vol 113 (14) ◽

pp. 3855-3860 ◽

Cited By ~ 30

Author(s):

Chen Peng ◽

Sherry L. Haller ◽

Masmudur M. Rahman ◽

Grant McFadden ◽

Stefan Rothenburg

Keyword(s):

Molecular Mechanisms ◽

Mammalian Species ◽

Ectopic Expression ◽

Specific Inhibitor ◽

Myxoma Virus ◽

Loss Of Function ◽

Antiviral Protein ◽

Protein Kinase R ◽

Field Isolates ◽

Species Specific

Myxoma virus (MYXV) is a rabbit-specific poxvirus, which is highly virulent in European rabbits. The attenuation of MYXV and the increased resistance of rabbits following the release of MYXV in Australia is one of the best-documented examples of host–pathogen coevolution. To elucidate the molecular mechanisms that contribute to the restriction of MYXV infection to rabbits and MYXV attenuation in the field, we have studied the interaction of the MYXV protein M156 with the host antiviral protein kinase R (PKR). In yeast and cell-culture transfection assays, M156 only inhibited rabbit PKR but not PKR from other tested mammalian species. Infection assays with human HeLa PKR knock-down cells, which were stably transfected with human or rabbit PKR, revealed that only human but not rabbit PKR was able to restrict MYXV infection, whereas both PKRs were able to restrict replication of a vaccinia virus (VACV) strain that lacks the PKR inhibitors E3 and K3. Inactivation of M156R led to MYXV virus attenuation in rabbit cells, which was rescued by the ectopic expression of VACV E3 and K3. We further show that a mutation in the M156 encoding gene that was identified in more than 50% of MYXV field isolates from Australia resulted in an M156 variant that lost its ability to inhibit rabbit PKR and led to virus attenuation. The species-specific inhibition of rabbit PKR by M156 and the M156 loss-of-function in Australian MYXV field isolates might thus contribute to the species specificity of MYXV and to the attenuation in the field, respectively.

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The spineless-aristapedia and tango bHLH-PAS proteins interact to control antennal and tarsal development in Drosophila

Development ◽

10.1242/dev.126.17.3937 ◽

1999 ◽

Vol 126 (17) ◽

pp. 3937-3945 ◽

Cited By ~ 3

Author(s):

R.B. Emmons ◽

D. Duncan ◽

P.A. Estes ◽

P. Kiefel ◽

J.T. Mosher ◽

...

Keyword(s):

Aryl Hydrocarbon Receptor ◽

Transcriptional Activation ◽

Molecular Mechanisms ◽

Target Genes ◽

Ectopic Expression ◽

Loss Of Function ◽

Helix Loop Helix ◽

Aryl Hydrocarbon ◽

Dna Binding Specificity ◽

Aryl Hydrocarbons

The Drosophila spineless (ss) gene encodes a basic-helix-loop-helix-PAS transcription factor that is required for proper specification of distal antennal identity, establishment of the tarsal regions of the legs, and normal bristle growth. ss is the closest known homolog of the mammalian aryl hydrocarbon receptor (Ahr), also known as the dioxin receptor. Dioxin and other aryl hydrocarbons bind to the PAS domain of Ahr, causing Ahr to translocate to the nucleus, where it dimerizes with another bHLH-PAS protein, the aryl hydrocarbon receptor nuclear translocator (Arnt). Ahr:Arnt heterodimers then activate transcription of target genes that encode enzymes involved in metabolizing aryl hydrocarbons. In this report, we present evidence that Ss functions as a heterodimer with the Drosophila ortholog of Arnt, Tango (Tgo). We show that the ss and tgo genes have a close functional relationship: loss-of-function alleles of tgo were recovered as dominant enhancers of a ss mutation, and tgo-mutant somatic clones show antennal, leg, and bristle defects almost identical to those caused by ss(−) mutations. The results of yeast two-hybrid assays indicate that the Ss and Tgo proteins interact directly, presumably by forming heterodimers. Coexpression of Ss and Tgo in Drosophila SL2 cells causes transcriptional activation of reporters containing mammalian Ahr:Arnt response elements, indicating that Ss:Tgo heterodimers are very similar to Ahr:Arnt heterodimers in DNA-binding specificity and transcriptional activation ability. During embryogenesis, Tgo is localized to the nucleus at sites of ss expression. This localization is lost in a ss null mutant, suggesting that Tgo requires heterodimerization for translocation to the nucleus. Ectopic expression of ss causes coincident ectopic nuclear localization of Tgo, independent of cell type or developmental stage. This suggests that the interaction of Ss and Tgo does not require additional signals, unlike the ligand-dependent interaction of Ahr and Arnt. Despite the very different biological roles of Ahr and Arnt in insects and mammals, the molecular mechanisms by which these proteins function appear to be largely conserved.

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hiPSC Modeling of Lineage-Specific Smooth Muscle Cell Defects Caused by TGFBR1 A230T Variant, and its Therapeutic Implications for Loeys-Dietz Syndrome

Circulation ◽

10.1161/circulationaha.121.054744 ◽

2021 ◽

Author(s):

Dong Zhou ◽

Hao Feng ◽

Ying Yang ◽

Tingting Huang ◽

Ping Qiu ◽

...

Keyword(s):

Smooth Muscle ◽

Combination Treatment ◽

Aortic Root ◽

Molecular Mechanisms ◽

Activin A ◽

Molecular Techniques ◽

Loss Of Function ◽

Molecular Defects ◽

Aortic Root Aneurysm ◽

And Function

Background: Loeys-Dietz Syndrome (LDS) is an inherited disorder predisposing individuals to thoracic aortic aneurysm and dissection (TAAD). Currently, there are no medical treatments except surgical resection. Although the genetic basis of LDS is well-understood, molecular mechanisms underlying the disease remain elusive impeding the development of a therapeutic strategy. In addition, aortic smooth muscle cells (SMC) have heterogenous embryonic origins depending on their spatial location, and lineage-specific effects of pathogenic variants on SMC function, likely causing regionally constrained LDS manifestations, have been unexplored. Methods: We identified an LDS family with a dominant pathogenic variant in TGFBR1 gene ( TGFBR1 A230T ) causing aortic root aneurysm and dissection. To accurately model the molecular defects caused by this mutation, we used human-induced pluripotent stem cells (hiPSC) from subject with normal aorta to generate hiPSC carrying TGFBR1 A230T , and corrected the mutation in patient-derived hiPSC using CRISPR-Cas9 gene editing. Following their lineage-specific SMC differentiation through cardiovascular progenitor cell (CPC) and neural crest stem cell (NCSC) lineages, we employed conventional molecular techniques and single-cell RNA-sequencing (scRNA-seq) to characterize the molecular defects. The resulting data led to subsequent molecular and functional rescue experiments employing Activin A and rapamycin. Results: Our results indicate the TGFBR1 A230T mutation impairs contractile transcript and protein levels, and function in CPC-SMC, but not in NCSC-SMC. ScRNA-seq results implicate defective differentiation even in TGFBR1 A230T/+ CPC-SMC including disruption of SMC contraction, and extracellular matrix formation. Comparison of patient-derived and mutation-corrected cells supported the contractile phenotype observed in the mutant CPC-SMC. TGFBR1 A230T selectively disrupted SMAD3 and AKT activation in CPC-SMC, and led to increased cell proliferation. Consistently, scRNA-seq revealed molecular similarities between a loss-of-function SMAD3 mutation ( SMAD3 c.652delA/+ ) and TGFBR1 A230T/+ . Lastly, combination treatment with Activin A and rapamycin during or after SMC differentiation significantly improved the mutant CPC-SMC contractile gene expression, and function; and rescued the mechanical properties of mutant CPC-SMC tissue constructs. Conclusions: This study reveals that a pathogenic TGFBR1 variant causes lineage-specific SMC defects informing the etiology of LDS-associated aortic root aneurysm. As a potential pharmacological strategy, our results highlight a combination treatment with Activin A and rapamycin that can rescue the SMC defects caused by the variant.

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Lasertechniques treatment of vascular malformations

Phlebologie ◽

10.1055/s-0037-1622304 ◽

2010 ◽

Vol 39 (03) ◽

pp. 167-175

Author(s):

M. Poetke ◽

P. Urban ◽

H.-P. Berlien

Keyword(s):

Endothelial Cells ◽

Spontaneous Regression ◽

Vascular System ◽

Vascular Malformations ◽

Clinical Importance ◽

Vascular Structure ◽

Laser Application ◽

Vascular Morphogenesis ◽

Structural Abnormalities

SummaryVascular malformations are structural abnormalities, errors of vascular morphogenesis, which can be localized in all parts of the vascular system. All vascular malformations by definition, are present at birth and grow proportionately with the child; their volume can change. In contrast to the haemangiomas, which only proliferate from the endothelial cells the division in stages is of clinical importance. Vascular malformations are divided from the part of vascular system, which is affected.In principle the techniques of laser application in congenital vascular tumours like haemangiomas and in vascular malformations are similar, but the aim is different. In tumours the aim is to induce regression, in vascular malformations the aim is to destroy the pathologic vascular structure because there is no spontaneous regression. This means that the parameters for treatment of vascular malformations must be more aggressive than for vascular tumours.

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Recent approaches for isolating and culturing mouse bone marrow-derived mesenchymal stromal stem cells

Current Stem Cell Research & Therapy ◽

10.2174/1574888x15666200708134337 ◽

2020 ◽

Vol 15 ◽

Author(s):

Basem M. Abdallah ◽

Hany M. Khattab

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Molecular Mechanisms ◽

Replicative Senescence ◽

Cellular Heterogeneity ◽

High Yield ◽

Mouse Strains ◽

Mouse Bone Marrow ◽

Differentiation Potential ◽

Stromal Stem Cells

: The isolation and culture of murine bone marrow-derived mesenchymal stromal stem cells (mBMSCs) have attracted great interest in terms of the pre-clinical applications of stem cells in tissue engineering and regenerative medicine. In addition, culturing mBMSCs is important for studying the molecular mechanisms of bone remodelling using relevant transgenic mice. Several factors have created challenges in the isolation and high-yield expansion of homogenous mBMSCs; these factors include low frequencies of bone marrow-derived mesenchymal stromal stem cells (BMSCs) in bone marrow, variation among inbred mouse strains, contamination with haematopoietic progenitor cells (HPCs), the replicative senescence phenotype and cellular heterogeneity. In this review, we provide an overview of nearly all protocols used for isolating and culturing mBMSCs with the aim of clarifying the most important guidelines for culturing highly purified mBMSC populations retaining in vitro and in vivo differentiation potential.

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TEAD4 modulated LncRNA MNX1-AS1 contributes to gastric cancer progression partly through suppressing BTG2 and activating BCL2

Molecular Cancer ◽

10.1186/s12943-019-1104-1 ◽

2020 ◽

Vol 19 (1) ◽

Cited By ~ 12

Author(s):

You Shuai ◽

Zhonghua Ma ◽

Weitao Liu ◽

Tao Yu ◽

Changsheng Yan ◽

...

Keyword(s):

Gastric Cancer ◽

Cancer Progression ◽

Molecular Mechanisms ◽

Mechanistic Model ◽

Ectopic Expression ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Tissue Samples ◽

Reporter Assays

Abstract Background Gastric cancer (GC) is the third leading cause of cancer-related mortality globally. Long noncoding RNAs (lncRNAs) are dysregulated in obvious malignancies including GC and exploring the regulatory mechanisms underlying their expression is an attractive research area. However, these molecular mechanisms require further clarification, especially upstream mechanisms. Methods LncRNA MNX1-AS1 expression in GC tissue samples was investigated via microarray analysis and further determined in a cohort of GC tissues via quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays. Cell proliferation and flow cytometry assays were performed to confirm the roles of MNX1-AS1 in GC proliferation, cell cycle regulation, and apoptosis. The influence of MNX1-AS1 on GC cell migration and invasion was explored with Transwell assays. A xenograft tumour model was established to verify the effects of MNX1-AS1 on in vivo tumourigenesis. The TEAD4-involved upstream regulatory mechanism of MNX1-AS1 was explored through ChIP and luciferase reporter assays. The mechanistic model of MNX1-AS1 in regulating gene expression was further detected by subcellular fractionation, FISH, RIP, ChIP and luciferase reporter assays. Results It was found that MNX1-AS1 displayed obvious upregulation in GC tissue samples and cell lines, and ectopic expression of MNX1-AS1 predicted poor clinical outcomes for patients with GC. Overexpressed MNX1-AS1 expression promoted proliferation, migration and invasion of GC cells markedly, whereas decreased MNX1-AS1 expression elicited the opposite effects. Consistent with the in vitro results, MNX1-AS1 depletion effectively inhibited the growth of xenograft tumour in vivo. Mechanistically, TEAD4 directly bound the promoter region of MNX1-AS1 and stimulated the transcription of MNX1-AS1. Furthermore, MNX1-AS1 can sponge miR-6785-5p to upregulate the expression of BCL2 in GC cells. Meanwhile, MNX1-AS1 suppressed the transcription of BTG2 by recruiting polycomb repressive complex 2 to BTG2 promoter regions. Conclusions Our findings demonstrate that MNX1-AS1 may be able to serve as a prognostic indicator in GC patients and that TEAD4-activatd MNX1-AS1 can promote GC progression through EZH2/BTG2 and miR-6785-5p/BCL2 axes, implicating it as a novel and potent target for the treatment of GC.

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The Phosphatidylserine Receptor TIM-1 Enhances Authentic Chikungunya Virus Cell Entry

Cells ◽

10.3390/cells10071828 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1828

Author(s):

Jared Kirui ◽

Yara Abidine ◽

Annasara Lenman ◽

Koushikul Islam ◽

Yong-Dae Gwon ◽

...

Keyword(s):

Chikungunya Virus ◽

Molecular Mechanisms ◽

Rna Virus ◽

Ectopic Expression ◽

Point Mutations ◽

Cell Entry ◽

Target Cells ◽

Human Hepatoma Cells ◽

Chikv Infection ◽

Phosphatidylserine Receptor

Chikungunya virus (CHIKV) is a re-emerging, mosquito-transmitted, enveloped positive stranded RNA virus. Chikungunya fever is characterized by acute and chronic debilitating arthritis. Although multiple host factors have been shown to enhance CHIKV infection, the molecular mechanisms of cell entry and entry factors remain poorly understood. The phosphatidylserine-dependent receptors, T-cell immunoglobulin and mucin domain 1 (TIM-1) and Axl receptor tyrosine kinase (Axl), are transmembrane proteins that can serve as entry factors for enveloped viruses. Previous studies used pseudoviruses to delineate the role of TIM-1 and Axl in CHIKV entry. Conversely, here, we use the authentic CHIKV and cells ectopically expressing TIM-1 or Axl and demonstrate a role for TIM-1 in CHIKV infection. To further characterize TIM-1-dependent CHIKV infection, we generated cells expressing domain mutants of TIM-1. We show that point mutations in the phosphatidylserine binding site of TIM-1 lead to reduced binding, entry, and infection of CHIKV. Ectopic expression of TIM-1 renders immortalized keratinocytes permissive to CHIKV, whereas silencing of endogenously expressed TIM-1 in human hepatoma cells reduces CHIKV infection. Altogether, our findings indicate that, unlike Axl, TIM-1 readily promotes the productive entry of authentic CHIKV into target cells.

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