scholarly journals The PRH/Hex repressor protein causes nuclear retention of Groucho/TLE co-repressors

2008 ◽  
Vol 417 (1) ◽  
pp. 121-132 ◽  
Author(s):  
Cecile Desjobert ◽  
Peter Noy ◽  
Tracey Swingler ◽  
Hannah  Williams ◽  
Kevin Gaston ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Dominant Negative ◽  
Vertebrate Development ◽  
Nuclear Retention ◽  
Subnuclear Localization ◽  
Cellular Processes ◽  
Haematopoietic Cells ◽  
Repressor Proteins ◽  
Homeobox Protein ◽  
Important Regulator

The PRH (proline-rich homeodomain) [also known as Hex (haematopoietically expressed homeobox)] protein is a transcription factor that functions as an important regulator of vertebrate development and many other processes in the adult including haematopoiesis. The Groucho/TLE (transducin-like enhancer) family of co-repressor proteins also regulate development and modulate the activity of many DNA-binding transcription factors during a range of diverse cellular processes including haematopoiesis. We have shown previously that PRH is a repressor of transcription in haematopoietic cells and that an Eh-1 (Engrailed homology) motif present within the N-terminal transcription repression domain of PRH mediates binding to Groucho/TLE proteins and enables co-repression. In the present study we demonstrate that PRH regulates the nuclear retention of TLE proteins during cellular fractionation. We show that transcriptional repression and the nuclear retention of TLE proteins requires PRH to bind to both TLE and DNA. In addition, we characterize a trans-dominant-negative PRH protein that inhibits wild-type PRH activity by sequestering TLE proteins to specific subnuclear domains. These results demonstrate that transcriptional repression by PRH is dependent on TLE availability and suggest that subnuclear localization of TLE plays an important role in transcriptional repression by PRH.

Transcriptional repression by nuclear receptors: mechanisms and role in disease

2000 ◽  
Vol 28 (4) ◽  
pp. 390-396 ◽  
Author(s):  
J. D. Love ◽  
J. T. Gooch ◽  
L. Nagy ◽  
V. K. K. Chatterjee ◽  
J. W. R. Schwabe
Keyword(s):  
Diabetes Mellitus ◽  
Thyroid Hormone ◽  
Ligand Binding ◽  
Nuclear Receptors ◽  
Transcriptional Repression ◽  
Dominant Negative ◽  
Receptor Interaction ◽  
Hormone Resistance ◽  
Thyroid Hormone Resistance ◽  
Repressor Proteins

Co-repressor proteins mediate transcriptional repression by nuclear receptors in the absence of ligand. The identification of a co-repressor-receptor interaction motif, and the finding that compressors and co-activators compete for the same site on the receptor, suggests a simple mechanism for the switch from repression to activation upon ligand binding. Defects in this mechanism result in dominant-negative receptors that repress transcription. Such receptors have been implicated in several clinically important diseases, including thyroid hormone resistance and diabetes mellitus.

scholarly journals Novel Roles of Hakai in Cell Proliferation and Oncogenesis

2009 ◽  
Vol 20 (15) ◽  
pp. 3533-3542 ◽  
Author(s):  
Angélica Figueroa ◽  
Hirokazu Kotani ◽  
Yoshinobu Toda ◽  
Krystyna Mazan-Mamczarz ◽  
Eva-Christina Mueller ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Rna Binding ◽  
Tumor Development ◽  
Human Colon ◽  
Dominant Negative ◽  
Interacting Protein ◽  
Cell Contacts ◽  
Cellular Processes ◽  
Important Regulator ◽  
Cell Cell

During tumor development, cells acquire multiple phenotypic changes upon misregulation of oncoproteins and tumor suppressor proteins. Hakai was originally identified as an E3 ubiquitin-ligase for the E-cadherin complex that regulates cell–cell contacts. Here, we present evidence that Hakai plays a crucial role in various cellular processes and tumorigenesis. Overexpression of Hakai affects not only cell–cell contacts but also proliferation in both epithelial and fibroblast cells. Furthermore, the knockdown of Hakai significantly suppresses proliferation of transformed epithelial cells. Expression of Hakai is correlated to the proliferation rate in human tissues and is highly up-regulated in human colon and gastric adenocarcinomas. Moreover, we identify PTB-associated splicing factor (PSF), an RNA-binding protein, as a novel Hakai-interacting protein. By using cDNA arrays, we have determined various specific PSF-associated mRNAs encoding proteins that are involved in several cancer-related processes. Hakai affects the ability of PSF to bind these mRNAs, and expression of PSF short hairpin RNA or a dominant-negative PSF mutant significantly suppresses proliferation of Hakai-overexpressing cells. Collectively, these results suggest that Hakai is an important regulator of cell proliferation and that Hakai may be an oncoprotein and a potential molecular target for cancer treatment.

scholarly journals Co-repressor, co-activator and general transcription factor: the many faces of the Sin3 histone deacetylase (HDAC) complex

2018 ◽  
Vol 475 (24) ◽  
pp. 3921-3932 ◽  
Author(s):  
Grace E. Adams ◽  
Aditya Chandru ◽  
Shaun M. Cowley
Keyword(s):  
Transcription Factor ◽  
Histone Deacetylase ◽  
Transcriptional Repression ◽  
Histone Deacetylation ◽  
Mammalian Development ◽  
Cellular Processes ◽  
General Transcription Factor ◽  
Repressor Proteins ◽  
Active Transcription ◽  
The Many

At face value, the Sin3 histone deacetylase (HDAC) complex appears to be a prototypical co-repressor complex, that is, a multi-protein complex recruited to chromatin by DNA bound repressor proteins to facilitate local histone deacetylation and transcriptional repression. While this is almost certainly part of its role, Sin3 stubbornly refuses to be pigeon-holed in quite this way. Genome-wide mapping studies have found that Sin3 localises predominantly to the promoters of actively transcribed genes. While Sin3 knockout studies in various species result in a combination of both up- and down-regulated genes. Furthermore, genes such as the stem cell factor, Nanog, are dependent on the direct association of Sin3 for active transcription to occur. Sin3 appears to have properties of a co-repressor, co-activator and general transcription factor, and has thus been termed a co-regulator complex. Through a series of unique domains, Sin3 is able to assemble HDAC1/2, chromatin adaptors and transcription factors in a series of functionally and compositionally distinct complexes to modify chromatin at both gene-specific and global levels. Unsurprisingly, therefore, Sin3/HDAC1 have been implicated in the regulation of numerous cellular processes, including mammalian development, maintenance of pluripotency, cell cycle regulation and diseases such as cancer.

scholarly journals TFEB Signalling-Related MicroRNAs and Autophagy

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 985
Author(s):  
Davide Corà ◽  
Federico Bussolino ◽  
Gabriella Doronzo
Keyword(s):  
Transcriptional Regulation ◽  
Stress Factors ◽  
Cellular Functions ◽  
Post Translational Modifications ◽  
Cellular Processes ◽  
Factor Deficiency ◽  
Transcription Factor Eb ◽  
Important Regulator ◽  
Response To Stress ◽  
Post Transcriptional Regulation

The oncogenic Transcription Factor EB (TFEB), a member of MITF-TFE family, is known to be the most important regulator of the transcription of genes responsible for the control of lysosomal biogenesis and functions, autophagy, and vesicles flux. TFEB activation occurs in response to stress factors such as nutrient and growth factor deficiency, hypoxia, lysosomal stress, and mitochondrial damage. To reach the final functional status, TFEB is regulated in multimodal ways, including transcriptional rate, post-transcriptional regulation, and post-translational modifications. Post-transcriptional regulation is in part mediated by miRNAs. miRNAs have been linked to many cellular processes involved both in physiology and pathology, such as cell migration, proliferation, differentiation, and apoptosis. miRNAs also play a significant role in autophagy, which exerts a crucial role in cell behaviour during stress or survival responses. In particular, several miRNAs directly recognise TFEB transcript or indirectly regulate its function by targeting accessory molecules or enzymes involved in its post-translational modifications. Moreover, the transcriptional programs triggered by TFEB may be influenced by the miRNA-mediated regulation of TFEB targets. Finally, recent important studies indicate that the transcription of many miRNAs is regulated by TFEB itself. In this review, we describe the interplay between miRNAs with TFEB and focus on how these types of crosstalk affect TFEB activation and cellular functions.

scholarly journals Pak1 regulates branching morphogenesis in 3D MDCK cell culture by a PIX and β1-integrin-dependent mechanism

2010 ◽  
Vol 299 (1) ◽  
pp. C21-C32 ◽  
Author(s):  
Michael P. Hunter ◽  
Mirjam M. Zegers
Keyword(s):  
Cell Culture ◽  
Mdck Cell ◽  
Three Dimensional ◽  
3D Culture ◽  
Branching Morphogenesis ◽  
Dominant Negative ◽  
Β1 Integrin ◽  
Blocking Antibody ◽  
Important Regulator ◽  
P21 Activated Kinase

Branching morphogenesis is a fundamental process in the development of the kidney. This process gives rise to a network of ducts, which form the collecting system. Defective branching can lead to a multitude of kidney disorders including agenesis and reduced nephron number. The formation of branching tubules involves changes in cell shape, cell motility, and reorganization of the cytoskeleton. However, the exact intracellular mechanisms involved are far from understood. We have used the three-dimensional (3D) Madin-Darby canine kidney (MDCK) cell culture system to study how p21-activated kinase 1 (Pak1), which is an important regulator of the cytoskeleton, modulates branching. Our data reveal that Pak1 plays a crucial role in regulating branching morphogenesis. Expression of a dominant-negative Pak1 mutant (DN-Pak1) in MDCK cysts resulted in the spontaneous formation of extensions and branching tubules. Cellular contractility and levels of phosphorylated myosin light chain (pMLC) were increased in DN-Pak1 cells in collagen. Expression of a DN-Pak1 mutant that does not bind to PIX (DN-Pak1-ΔPIX) failed to form extensions in collagen and did not have increased contractility. This shows that the DN-Pak1 mutant requires PIX binding to generate extensions and increased contractility in 3D culture. Furthermore, a β1-integrin function-blocking antibody (AIIB2) inhibited the formation of branches and blocked the increased contractility in DN-Pak1 cysts. Taken together, our work shows that DN-Pak1-induced branching morphogenesis requires PIX binding and β1-integrin signaling.

scholarly journals Rett-causing mutations reveal two domains critical for MeCP2 function and for toxicity in MECP2 duplication syndrome mice

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Laura Dean Heckman ◽  
Maria H Chahrour ◽  
Huda Y Zoghbi
Keyword(s):  
Transcriptional Repression ◽  
Neurological Disorder ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Loss Of Function ◽  
Gene Encoding ◽  
C Terminus ◽  
Mecp2 Duplication Syndrome ◽  
Negative Effect ◽  
Duplication Syndrome

Loss of function of the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2) causes the progressive neurological disorder Rett syndrome (RTT). Conversely, duplication or triplication of Xq28 causes an equally wide-ranging progressive neurological disorder, MECP2 duplication syndrome, whose features overlap somewhat with RTT. To understand which MeCP2 functions cause toxicity in the duplication syndrome, we generated mouse models expressing endogenous Mecp2 along with a RTT-causing mutation in either the methyl-CpG binding domain (MBD) or the transcriptional repression domain (TRD). We determined that both the MBD and TRD must function for doubling MeCP2 to be toxic. Mutating the MBD reproduces the null phenotype and expressing the TRD mutant produces milder RTT phenotypes, yet both mutations are harmless when expressed with endogenous Mecp2. Surprisingly, mutating the TRD is more detrimental than deleting the entire C-terminus, indicating a dominant-negative effect on MeCP2 function, likely due to the disruption of a basic cluster.

scholarly journals Arabidopsis ALIX is required for the endosomal localization of the deubiquitinating enzyme AMSH3

2015 ◽  
Vol 112 (40) ◽  
pp. E5543-E5551 ◽  
Author(s):  
Kamila Kalinowska ◽  
Marie-Kristin Nagel ◽  
Kaija Goodman ◽  
Laura Cuyas ◽  
Franziska Anzenberger ◽  
...  
Keyword(s):  
Cellular Level ◽  
Deubiquitinating Enzymes ◽  
Interacting Protein ◽  
Endosomal Sorting ◽  
Cellular Processes ◽  
Late Endosomes ◽  
Knockout Mutants ◽  
Important Regulator

Ubiquitination is a signal for various cellular processes, including for endocytic degradation of plasma membrane cargos. Ubiquitinating as well as deubiquitinating enzymes (DUBs) can regulate these processes by modifying the ubiquitination status of target protein. Although accumulating evidence points to the important regulatory role of DUBs, the molecular basis of their regulation is still not well understood. Associated molecule with the SH3 domain of signal transduction adaptor molecule (STAM) (AMSH) is a conserved metalloprotease DUB in eukaryotes. AMSH proteins interact with components of the endosomal sorting complex required for transport (ESCRT) and are implicated in intracellular trafficking. To investigate how the function of AMSH is regulated at the cellular level, we carried out an interaction screen for the Arabidopsis AMSH proteins and identified the Arabidopsis homolog of apoptosis-linked gene-2 interacting protein X (ALIX) as a protein interacting with AMSH3 in vitro and in vivo. Analysis of alix knockout mutants in Arabidopsis showed that ALIX is essential for plant growth and development and that ALIX is important for the biogenesis of the vacuole and multivesicular bodies (MVBs). Cell biological analysis revealed that ALIX and AMSH3 colocalize on late endosomes. Although ALIX did not stimulate AMSH3 activity in vitro, in the absence of ALIX, AMSH3 localization on endosomes was abolished. Taken together, our data indicate that ALIX could function as an important regulator for AMSH3 function at the late endosomes.

scholarly journals Transcriptional Repression by the Human Homeobox Protein EVX1 in Transfected Mammalian Cells

1995 ◽  
Vol 270 (46) ◽  
pp. 27695-27701 ◽  
Author(s):  
Paola Briata ◽  
Rinke Van De Werken ◽  
Irma Airoldi ◽  
Cristina Ilengo ◽  
Erica Di Blas ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Mammalian Cells ◽  
Homeobox Protein

The protease MBTPS2 is an important regulator of several cellular processes, especially in health and sickness

2021 ◽  
Author(s):  
Moataz Dowaidar
Keyword(s):  
Active Sites ◽  
Peptide Bond ◽  
Cellular Processes ◽  
Disease States ◽  
Tremendous Progress ◽  
Catalytic Sites ◽  
Important Regulator ◽  
Catalytic Active Sites ◽  
Proteolytic Action ◽  
Health And Sickness

Since the identification of MBTPS2 in 1997, tremendous progress has been made in determining the protease's functions. The protease has developed from an element of the SREBP cleavage machinery to an important regulator of several cellular processes, especially in health and sickness. With this newfound information from biochemical and structural biology, S2P's proteolytic action through peptide bond hydrolysis can occur in the membrane, providing a conceptual framework for appreciating S2P's roles in other aspects, and showing that many other substrates rely on S2P for their survival. In addition, we discovered the identity of both of S2P's catalytic active sites, an essential finding as the activity of the proteolysis as well as the pathogenesis of MBTPS2-caused illnesses seems to be connected to the molecular and biochemical features of the catalytic sites. Additionally, MBTPS2 causes different diseases, possibly illustrating the pleiotropic nature of the protein. Also, while the ailments reported thus far are all due to mutations that cause MBTPS2 to lose function, other variants that cause MBTPS2 to be hyperactive have not been examined. Nevertheless, recognizing the related sickness pathomechanism is a challenge. Pursuing these challenging technical areas would most definitely enhance our understanding of MBTPS2 in disease states. MBTPS2 appears to be nearing the solution to many of the remaining fundamental questions surrounding the mechanism of its action, as well as being a therapeutic target for new therapies.

scholarly journals An inducible CRISPR interference library for genetic interrogation of Saccharomyces cerevisiae biology

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Amir Momen-Roknabadi ◽  
Panos Oikonomou ◽  
Maxwell Zegans ◽  
Saeed Tavazoie
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcriptional Repression ◽  
Nucleosome Occupancy ◽  
Design Parameters ◽  
Experimental Conditions ◽  
Crispr Interference ◽  
Cellular Processes ◽  
Genome Wide ◽  
Reliable Assessment ◽  
A Genome

AbstractGenome-scale CRISPR interference (CRISPRi) is widely utilized to study cellular processes in a variety of organisms. Despite the dominance of Saccharomyces cerevisiae as a model eukaryote, an inducible genome-wide CRISPRi library in yeast has not yet been presented. Here, we present a genome-wide, inducible CRISPRi library, based on spacer design rules optimized for S. cerevisiae. We have validated this library for genome-wide interrogation of gene function across a variety of applications, including accurate discovery of haploinsufficient genes and identification of enzymatic and regulatory genes involved in adenine and arginine biosynthesis. The comprehensive nature of the library also revealed refined spacer design parameters for transcriptional repression, including location, nucleosome occupancy and nucleotide features. CRISPRi screens using this library can identify genes and pathways with high precision and a low false discovery rate across a variety of experimental conditions, enabling rapid and reliable assessment of genetic function and interactions in S. cerevisiae.

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