scholarly journals Sarcomeres regulate cardiomyocyte maturation through MRTF-SRF signaling

2019 ◽  
Author(s):  
Yuxuan Guo ◽  
Blake D. Jardin ◽  
Isha Sethi ◽  
Qing Ma ◽  
Behzad Moghadaszadeh ◽  
...  
Keyword(s):  
Feedback Loop ◽  
Dominant Negative ◽  
Structural Defects ◽  
Signaling Networks ◽  
Strongly Correlated ◽  
Transcriptional Dysregulation ◽  
Morphological Defects ◽  
Transcriptional Changes ◽  
Heart Contraction ◽  
Sarcomere Assembly

AbstractCardiomyocyte maturation is essential for robust heart contraction throughout life. The signaling networks governing cardiomyocyte maturation remain poorly defined. Our prior studies established the transcription factor SRF as a key regulator of the assembly of sarcomeres, the contractile unit of cardiomyocytes. Whether sarcomeres regulate other aspects of maturation remains unclear. Here we generated mice with cardiomyocyte specific, mosaic mutation of α-actinin-2 (Actn2), a key organizer of sarcomeres, to study its cell-autonomous role in cardiomyocyte maturation. In addition to the expected structural defects, Actn2 mutation triggered dramatic transcriptional dysregulation, which strongly correlated with transcriptional changes observed in SRF-depleted cardiomyocytes. Actn2 mutation increased monomeric actin, which perturbed the nuclear localization of the SRF cofactor MRTFA. Overexpression of a dominant-negative MRTFA mutant was sufficient to recapitulate the transcriptional and morphological defects in Actn2 and Srf mutant cardiomyocytes. Together, we demonstrate that ACTN2-based sarcomere assembly and MRTF-SRF signaling establish a positive feedback loop that promotes cardiomyocyte maturation.

scholarly journals Sarcomeres regulate murine cardiomyocyte maturation through MRTF-SRF signaling

2020 ◽  
Vol 118 (2) ◽  
pp. e2008861118
Author(s):  
Yuxuan Guo ◽  
Yangpo Cao ◽  
Blake D. Jardin ◽  
Isha Sethi ◽  
Qing Ma ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Serum Response Factor ◽  
Mitochondrial Genes ◽  
Dominant Negative ◽  
Response Factor ◽  
Strongly Correlated ◽  
Transcriptional Dysregulation ◽  
Transcriptional Changes ◽  
Major Bottleneck ◽  
Serum Response

The paucity of knowledge about cardiomyocyte maturation is a major bottleneck in cardiac regenerative medicine. In development, cardiomyocyte maturation is characterized by orchestrated structural, transcriptional, and functional specializations that occur mainly at the perinatal stage. Sarcomeres are the key cytoskeletal structures that regulate the ultrastructural maturation of other organelles, but whether sarcomeres modulate the signal transduction pathways that are essential for cardiomyocyte maturation remains unclear. To address this question, here we generated mice with cardiomyocyte-specific, mosaic, and hypomorphic mutations of α-actinin-2 (Actn2) to study the cell-autonomous roles of sarcomeres in postnatal cardiomyocyte maturation. Actn2 mutation resulted in defective structural maturation of transverse-tubules and mitochondria. In addition, Actn2 mutation triggered transcriptional dysregulation, including abnormal expression of key sarcomeric and mitochondrial genes, and profound impairment of the normal progression of maturational gene expression. Mechanistically, the transcriptional changes in Actn2 mutant cardiomyocytes strongly correlated with those in cardiomyocytes deleted of serum response factor (SRF), a critical transcription factor that regulates cardiomyocyte maturation. Actn2 mutation increased the monomeric form of cardiac α-actin, which interacted with the SRF cofactor MRTFA and perturbed its nuclear localization. Overexpression of a dominant-negative MRTFA mutant was sufficient to recapitulate the morphological and transcriptional defects in Actn2 and Srf mutant cardiomyocytes. Together, these data indicate that Actn2-based sarcomere organization regulates structural and transcriptional maturation of cardiomyocytes through MRTF-SRF signaling.

PGE2 potentiates tonicity-induced COX-2 expression in renal medullary cells in a positive feedback loop involving EP2-cAMP-PKA signaling

2009 ◽  
Vol 296 (1) ◽  
pp. C75-C87 ◽  
Author(s):  
Daniela Steinert ◽  
Christoph Küper ◽  
Helmut Bartels ◽  
Franz-X. Beck ◽  
Wolfgang Neuhofer
Keyword(s):  
Osmotic Stress ◽  
Cell Survival ◽  
Positive Feedback ◽  
Feedback Loop ◽  
Mdck Cells ◽  
Dominant Negative ◽  
Dibutyryl Camp ◽  
Positive Feedback Loop ◽  
Cox 2 ◽  
Medullary Cells

Cyooxygenase-2 (COX-2)-derived PGE2 is critical for the integrity and function of renal medullary cells during antidiuresis. The present study extended our previous finding that tonicity-induced COX-2 expression is further stimulated by the major COX-2 product PGE2 and investigated the underlying signaling pathways and the functional relevance of this phenomenon. Hyperosmolality stimulated COX-2 expression and activity in Madin-Darby canine kidney (MDCK) cells, a response that was further increased by PGE2-cAMP signaling, suggesting the existence of a positive feedback loop. This effect was diminished by AH-6809, an EP2 antagonist, and by the PKA inhibitor H-89, but not by AH-23848, an EP4 antagonist. The effect of PGE2 was mimicked by forskolin and dibutyryl-cAMP, suggesting that the stimulatory effect of PGE2 on COX-2 is mediated by a cAMP-PKA-dependent mechanism. Accordingly, cAMP-responsive element (CRE)-driven reporter activity paralleled the effects of PGE2, AH-6809, AH-23848, H-89, forskolin, and dibutyryl-cAMP on COX-2 expression. In addition, the stimulatory effect of PGE2 on tonicity-induced COX-2 expression was blunted in cells transfected with dominant-negative CRE binding (CREB) protein, as was the case in a COX-2 promoter reporter construct in which a putative CRE was deleted. Furthermore, PGE2 resulted in PKA-dependent phosphorylation of the pro-apoptotic protein Bad at Ser155, a mechanism that is known to inactivate Bad, which coincided with reduced caspase-3 activity during osmotic stress. Conversely, pharmacological interruption of the PGE2-EP2-cAMP-PKA pathway abolished Ser155 phosphorylation of Bad and blunted the protective effect of PGE2 on cell survival during osmotic stress. These observations indicate the existence of a positive feedback loop of PGE2 on COX-2 expression during osmotic stress, an effect that apparently is mediated by EP2-cAMP-PKA signaling, and that contributes to cell survival under hypertonic conditions.

scholarly journals Mutations in type I collagen genes resulting in osteogenesis imperfecta in humans.

2002 ◽  
Vol 49 (2) ◽  
pp. 433-441 ◽  
Author(s):  
Anna Gajko-Galicka
Keyword(s):  
Osteogenesis Imperfecta ◽  
Bone Disease ◽  
Type I Collagen ◽  
Wide Spectrum ◽  
Dominant Negative ◽  
Structural Defects ◽  
Collagen Molecule ◽  
Type I ◽  
Structural Protein ◽  
Collagen Genes

Osteogenesis imperfecta (OI), commonly known as "brittle bone disease", is a dominant autosomal disorder characterized by bone fragility and abnormalities of connective tissue. Biochemical and molecular genetic studies have shown that the vast majority of affected individuals have mutations in either the COL1A1 or COL1A2 genes that encode the chains of type I procollagen. OI is associated with a wide spectrum of phenotypes varying from mild to severe and lethal conditions. The mild forms are usually caused by mutations which inactivate one allele of COL1A1 gene and result in a reduced amount of normal type I collagen, while the severe and lethal forms result from dominant negative mutations in COL1A1 or COL1A2 which produce structural defects in the collagen molecule. The most common mutations are substitutions of glycine residues, which are crucial to formation and function of the collagen triple helix, by larger amino acids. Although type I collagen is the major structural protein of both bone and skin, the mutations in type I collagen genes cause a bone disease. Some reports showed that the mutant collagen can be expressed differently in bone and in skin. Since most mutations identified in OI are dominant negative, the gene therapy requires a fundamentally different approach from that used for genetic-recessive disorders. The antisense therapy, by reducing the expression of mutant genes, is able to change a structural mutation into a null mutation, and thus convert severe forms of the disease into mild OI type I.

Effects of heterodimerization and proteolytic processing on Derrière and Nodal activity: implications for mesoderm induction in Xenopus

Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3089-3103 ◽  
Author(s):  
Peter M. Eimon ◽  
Richard M. Harland
Keyword(s):  
Feedback Loop ◽  
Expression System ◽  
Direct Interaction ◽  
Proteolytic Processing ◽  
Dominant Negative ◽  
Mesoderm Induction ◽  
Mesoderm Formation ◽  
Oocyte Expression System ◽  
The Right ◽  
Tgfβ Superfamily

Derrière is a recently discovered member of the TGFβ superfamily that can induce mesoderm in explant assays and is expressed at the right time and location to mediate mesoderm induction in response to VegT during Xenopus embryogenesis. We show that the ability of Derrière to induce dorsal or ventral mesoderm depends strictly on the location of expression and that a dominant-negative Derrière cleavage mutant completely blocks all mesoderm formation when ectopically expressed. This differs from the activity of similar Xnr2 cleavage mutant constructs, which are secreted and retain signaling activity. Additional analysis of mesoderm induction by Derrière and members of the Nodal family indicates that these molecules are involved in a mutual positive-feedback loop and antagonism of either one of the signals can reduce the other. Interaction between Derrière and members of the Nodal family is also shown to occur through the formation of heterodimeric ligands. Using an oocyte expression system we show direct interaction between the mature Derrière ligand and members of both the Nodal and BMP families. Taken together, these findings indicate that Derrière and Nodal proteins probably work cooperatively to induce mesoderm throughout the marginal zone during early Xenopus development.

Cas, Fak and Pyk2 function in diverse signaling cascades to promote Yersinia uptake

2002 ◽  
Vol 115 (13) ◽  
pp. 2689-2700 ◽  
Author(s):  
Pamela J. Bruce-Staskal ◽  
Cheryl L. Weidow ◽  
Jennifer J. Gibson ◽  
Amy H. Bouton
Keyword(s):  
Tyrosine Kinases ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Signaling Networks ◽  
Rac1 Activity ◽  
Morphological Defects ◽  
Cell Adhesion And Migration ◽  
Uptake Process ◽  
Insight Into

The interplay between pathogen-encoded virulence factors and host cell signaling networks is critical for both the establishment and clearance of microbial infections. Yersinia uptake into host cells serves as an in vitro model for exploring how host cells respond to Yersinia adherence. In this study, we provide insight into the molecular nature and regulation of signaling networks that contribute to the uptake process. Using a reconstitution approach in Fak-/- fibroblasts, we have been able to specifically address the interplay between Fak, Cas and Pyk2 in this process. We show that both Fak and Cas play roles in the Yersinia uptake process and that Cas can function in a novel pathway that is independent of Fak. Fak-dependent Yersinia uptake does not appear to involve Cas-Crk signaling. By contrast, Cas-mediated uptake in the absence of Fak requires Crk as well as the protein tyrosine kinases Pyk2 and Src. In spite of these differences, the requirement for Rac1 activity is a common feature of both pathways. Furthermore, blocking the function of either Fak or Cas induces similar morphological defects in Yersinia internalization, which are manifested by incomplete membrane protrusive activity that is consistent with an inhibition of Rac1 activity. Pyk2 also functions in Yersinia uptake by macrophages, which are physiologically important for clearing Yersinia infections. Taken together, these data provide new insight into the host cellular signaling networks that are initiated upon infection with Y. pseudotuberculosis. Importantly, these findings also contribute to a better understanding of other cellular processes that involve actin remodeling, including the host response to other microbial pathogens, cell adhesion and migration.

Molecular effects of loss of BMPR2 signaling in smooth muscle in a transgenic mouse model of PAH

2007 ◽  
Vol 292 (6) ◽  
pp. L1556-L1563 ◽  
Author(s):  
Yuji Tada ◽  
Susan Majka ◽  
Michelle Carr ◽  
Julie Harral ◽  
Daniel Crona ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Disease Process ◽  
Dominant Negative ◽  
Rt Pcr ◽  
Female Mice ◽  
Molecular Events ◽  
Dominant Negative Form ◽  
Transcriptional Changes ◽  
Interfering Rna

Idiopathic pulmonary arterial hypertension (IPAH) in human patients is associated with mutations in type 2 receptor for the bone morphogenic protein pathway (BMPR2). Mice expressing an inducible dominant negative form of BMPR2 in smooth muscle develop elevated right ventricular pressures when the transgene is activated. We hypothesized that transcriptional changes in these mice may allow insight into the early molecular events leading to IPAH. Microarray analysis was used to examine the transcriptional changes induced in whole lung by loss of normal smooth muscle cell (SMC) BMPR2 signaling in adult male or female mice (12 wk at time of death) expressing the transgene for either 1 or 8 wk. Our key results include a decrease in markers of smooth muscle differentiation, an increase in cytokines and markers of immune response, particularly in female mice, and a decrease in angiogenesis-related genes. These broad patterns of gene expression appear as early as 1 wk and are well established by 8 wk. Results were confirmed by quantitative RT-PCR to RNA from individual mice. Primary pulmonary artery SMC cultures transfected with small interfering RNA to BMPR2 also show loss of SMC markers myosin heavy chain 11 and calponin by quantitative RT-PCR and Western blot. These studies show classes of genes differentially regulated in response to loss of BMPR2 in SMC in vivo with clear relevance to the IPAH disease process, suggesting that the relevance of BMPR2 dysregulation may extend beyond proliferation.

Influence of Solidification Speed on Quality and Quantity of Structural Defects in Fe61Co10Zr2.5Hf2.5Y2W2B20 Amorphous Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 1074-1077 ◽  
Author(s):  
Marcin Nabiałek ◽  
Marcin Dośpiał ◽  
Michał Szota ◽  
Paweł Pietrusiewicz
Keyword(s):  
Amorphous Alloy ◽  
Cooling Rate ◽  
Melt Spinning ◽  
Structural Defects ◽  
Strongly Correlated ◽  
X Ray Diffraction ◽  
Linear Type ◽  
X Ray ◽  
Solidification Speed ◽  
Point Type

The microstructure of Fe61Co10Zr2,5Hf2,5Nb2W2B20 amorphous alloy in the form of ribbons obtained by classical melt spinning and plates obtained by an induction suction method were investigated using X-ray diffraction. The type of structural defects were studied by analysis of the magnetization characteristics near ferromagnetic saturation of the sample. It was shown that the presence of structural defects is strongly correlated with sample thickness and production process. It was shown that ribbons with cooling rate between 105-106 K/s have point type defects, wires obtained with lower cooling rate between 101-102 K/s, have linear type defect (quasi-dislocation dipoles). crystallization.

scholarly journals A meta-analysis of transcriptomic profiles from Huntington’s disease patients substantiates the pathophysiological role of CDC42, NFY, DLX1 and PRMT3

2021 ◽  
Author(s):  
Manuel Seefelder ◽  
Stefan Kochanek
Keyword(s):  
Protein Transport ◽  
Target Genes ◽  
Meta Analysis ◽  
Mrna Levels ◽  
Strongly Correlated ◽  
Transcriptome Data ◽  
Transcriptional Dysregulation ◽  
Pathophysiological Role ◽  
The Brain

AbstractDescription of robust transcriptomic alterations in Huntington s disease is essential to identify targets for biochemical studies and drug development. Here, we analysed publicly available transcriptome data from the brain and blood of 449 HD patients and 212 healthy controls. We identified 737 and 661 genes with robustly altered mRNA levels in the brain and blood of HD patients, respectively. In the brain, a subnetwork of 320 genes strongly correlated with HD and was enriched in transport-related genes. Bioinformatical analysis of this subnetwork highlighted CDC42, PAK1, NFY, DLX1, HMGN3, and PRMT3. Moreover, we found that CREB1 can regulate 78.0 % of genes whose mRNA levels correlated with HD in the blood of patients. Our meta-analysis indicates that alterations in protein transport, metabolism, transcriptional regulation, and CDC42-mediated functions are central features of HD. Further our data substantiate the role of transcriptional regulators that have not been reported in the context of HD such as DLX1, HMGN3 and PRMT3 and strongly suggest transcriptional dysregulation of NFY and its target genes across tissues.

Pax3 induces cell aggregation and regulates phenotypic mesenchymal-epithelial interconversion

2002 ◽  
Vol 115 (3) ◽  
pp. 517-529 ◽  
Author(s):  
O'Neil Wiggan ◽  
Marc P. Fadel ◽  
Paul A. Hamel
Keyword(s):  
Embryonic Development ◽  
Epithelial To Mesenchymal Transition ◽  
Morphological Changes ◽  
Cell Aggregation ◽  
Structural Defects ◽  
Mesenchymal Transition ◽  
Mammalian Cell Lines ◽  
Morphological Defects ◽  
Pax Family

Paired box-containing transcription factors play fundamental roles in pattern formation during embryonic development of diverse organisms ranging from Drosophila to mammals. Although mutations to Pax3 and other Pax-family genes in both mice and humans result in numerous tissue-specific morphological defects, little is known about the cellular processes that Pax genes regulate. We show that extopic Pax3 expression in two distinct phenotypically mesenchymal mammalian cell lines induces the formation of multi-layered condensed cell aggregates with epithelial characteristics. For one of these lines, we showed further that Pax3-induced cell aggregation is accompanied by specific morphological changes, including a significant reduction in cell size, altered cell shape and dramatic alterations to both membrane and cytoskeleton architecture. In addition to mediating a phenotypic mesenchymal-to-epithelial transition, Pax3 also establishes the conditions in these cells for a subsequent hepatocyte growth factor/scatter factor(HGF/SF)-induced phenotypic epithelial-to-mesenchymal transition. Thus, our data show a novel morphogenetic activity for Pax3 which, when absent in vivo,is predicted to give rise to the observed structural defects in somites and the neural tube during embryonic development.

scholarly journals Early epigenomic and transcriptional changes reveal Elk-1 transcription factor as a therapeutic target in Huntington’s disease

2019 ◽  
Vol 116 (49) ◽  
pp. 24840-24851 ◽  
Author(s):  
Ferah Yildirim ◽  
Christopher W. Ng ◽  
Vincent Kappes ◽  
Tobias Ehrenberger ◽  
Siobhan K. Rigby ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Disease Onset ◽  
Beneficial Effects ◽  
Transcriptional Dysregulation ◽  
Clinical Onset ◽  
Transcriptional Changes ◽  
Chromatin Profiling

Huntington’s disease (HD) is a chronic neurodegenerative disorder characterized by a late clinical onset despite ubiquitous expression of the mutant Huntingtin gene (HTT) from birth. Transcriptional dysregulation is a pivotal feature of HD. Yet, the genes that are altered in the prodromal period and their regulators, which present opportunities for therapeutic intervention, remain to be elucidated. Using transcriptional and chromatin profiling, we found aberrant transcription and changes in histone H3K27acetylation in the striatum of R6/1 mice during the presymptomatic disease stages. Integrating these data, we identified the Elk-1 transcription factor as a candidate regulator of prodromal changes in HD. Exogenous expression of Elk-1 exerted beneficial effects in a primary striatal cell culture model of HD, and adeno-associated virus-mediated Elk-1 overexpression alleviated transcriptional dysregulation in R6/1 mice. Collectively, our work demonstrates that aberrant gene expression precedes overt disease onset in HD, identifies the Elk-1 transcription factor as a key regulator linked to early epigenetic and transcriptional changes in HD, and presents evidence for Elk-1 as a target for alleviating molecular pathology in HD.

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