scholarly journals PTTG’s C-terminal PXXP motifs modulate critical cellular processes in vitro

2004 ◽  
Vol 33 (3) ◽  
pp. 663-677 ◽  
Author(s):  
K Boelaert ◽  
R Yu ◽  
L A Tannahill ◽  
A L Stratford ◽  
F L Khanim ◽  
...  
Keyword(s):  
Cell Transformation ◽  
Phosphorylation Site ◽  
Null Cell ◽  
Human Pituitary ◽  
Multifunctional Protein ◽  
Cellular Processes ◽  
Proliferation Assays ◽  
Nih 3T3

Human pituitary tumor-transforming gene (PTTG), known also as securin, is a multifunctional protein implicated in the control of mitosis and the pathogenesis of thyroid, colon, oesophageal and other tumour types. Critical to PTTG function is a C-terminal double PXXP motif, forming a putative SH3-interacting domain and housing the gene’s sole reported phosphorylation site. The exact role of phosphorylation and PXXP structure in the modulation of PTTG action in vitro remains poorly understood. We therefore examined the mitotic, transformation, proliferation and transactivation function of the C-terminal PXXP motifs of human PTTG. Live-cell imaging studies using an EGFP-PTTG construct indicated that PTTG’s regulation of mitosis is retained regardless of phosphorylation status. Colony-formation assays demonstrated that phosphorylation of PTTG may act as a potent inhibitor of cell transformation. In proliferation assays, NIH-3T3 cells stable transfected and overexpressing mutations preventing PTTG phosphorylation (Phos-) showed significantly increased [3H]thymidine incorporation compared with WT, whereas mutants mimicking constitutive phosphorylation of PTTG (Phos+) exhibited reduced cell proliferation. We demonstrated that PTTG transactivation of FGF-2 in primary thyroid and PTTG-null cell lines was not affected by PTTG phosphorylation but was prevented by a mutant disrupting the PXXP motifs (SH3-). Taken together, our data suggest that PXXP structure and phosphorylation are likely to exert independent and critical influences upon PTTG’s diverse actions in vitro.

scholarly journals A New MAP Kinase Protein Involved in Estradiol-Stimulated Reproduction of the Helminth ParasiteTaenia crassiceps

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Galileo Escobedo ◽  
Gloria Soldevila ◽  
Guadalupe Ortega-Pierres ◽  
Jesús Ramsés Chávez-Ríos ◽  
Karen Nava ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Map Kinases ◽  
Host Cells ◽  
Cross Contamination ◽  
Flow Cytometry Analysis ◽  
Cellular Processes ◽  
17Β Estradiol ◽  
Activation Motif

MAP kinases (MAPK) are involved in the regulation of cellular processes such as reproduction and growth. In parasites, the role of MAPK has been scarcely studied. Here, we describe the participation of an ERK-like protein in estrogen-dependent reproduction of the helminth parasiteTaenia crassiceps. Our results show that 17β-estradiol induces a concentration-dependent increase in the bud number of in vitro cultured cysticerci. If parasites are also incubated in presence of an ERK-inhibitor, the stimulatory effect of estrogen is blocked. The expression of ERK-like mRNA and its corresponding protein was detected in the parasite. The ERK-like protein was over-expressed by all treatments. Nevertheless, a strong induction of phosphorylation of this protein was observed only in response to 17β-estradiol. Cross-contamination by host cells was discarded by flow cytometry analysis. Parasite cells expressing the ERK-like protein were exclusively located at the subtegument tissue by confocal microscopy. Finally, the ERK-like protein was separated by bidimensional electrophoresis and then sequenced, showing the conserved TEY activation motif, typical of all known ERK 1/2 proteins. Our results show that an ERK-like protein is involved in the molecular signalling during the interaction between the host andT. crassiceps, and may be considered as target for anti-helminth drugs design.

Expression of human recombinant plasminogen activators enhances invasion and experimental metastasis of H-ras-transformed NIH 3T3 cells

1989 ◽  
Vol 9 (5) ◽  
pp. 2133-2141
Author(s):  
J H Axelrod ◽  
R Reich ◽  
R Miskin
Keyword(s):  
Serine Proteinase ◽  
Tissue Type ◽  
Metastatic Lesions ◽  
Metastatic Behavior ◽  
Sequence Encoding ◽  
Direct Genetic Evidence ◽  
Nih 3T3 ◽  
Gene Transfer Technique

The gene transfer technique was used to examine the role of plasminogen activator (PA) in the invasive and metastatic behavior of tumorigenic cells. H-ras-transformed NIH 3T3 clonal cells producing a very low level of PA were generated and further transfected with an expression plasmid containing a cDNA sequence encoding either the urokinase-type or the tissue-type human PA. Compared with the parental transformed cells, clonal cells expressing high levels of both types of recombinant PA invaded more rapidly through a basement membrane reconstituted in vitro. Furthermore, cells expressing high levels of recombinant urokinase-type PA also caused a higher incidence of pulmonary metastatic lesions after intravenous injection into nude mice. Both activities were reduced by the serine proteinase inhibitor EACA; invasion was also suppressed by antibodies blocking the activity of human PAs and by the synthetic collagenase inhibitor SC-44463. These findings provide direct genetic evidence for a causal role of PA in invasive and metastatic activities.

Abstract 115: Nuclear CaMKII is a Histone H3 Kinase that Remodels Chromatin During Cardiac Hypertrophy

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Salma Mahmoud ◽  
Muhammad Kunhi ◽  
Gillian H Little ◽  
Yan Bai ◽  
Woojin An ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Cardiac Muscle ◽  
Chromatin Remodeling ◽  
Cellular Proliferation ◽  
Recombinant Adenovirus ◽  
Phosphorylation Site ◽  
Histone H3 ◽  
Functional Link

Background and Purpose: Calcium/calmodulin-dependent protein kinase II (CaMKII) is a ubiquitous serine/threonine kinase implicated in pathological events such as cardiac hypertrophy. In this study we investigated the role of a specific nuclear isoform of CaMKII in chromatin remodeling and in transcriptional regulation in cardiac muscle. Methods: Comprehensive experimental approaches performed in primary cardiomyocyte cultures were used including chromatin immunoprecipitation assays (ChIP), q-PCR, chromatin remodeling assays, in vitro phosphorylation/transcription assays, production of recombinant adenovirus, siRNA technology, fluorescence microscopy and mass spectrometry. Results: We found that CaMKIIδB targets specific components of chromatin during cardiac hypertrophy and binds to nucleosomes through its association domain in a cooperative model. CaMKIIδB also increased chromatin relaxation, and this action was dependent on its kinase activity. The observation that CaMKIIδB interacts with chromatin suggested to us that histones maybe novel substrates of the kinase in cardiac muscle. To test this hypothesis, we performed in vitro kinase assays and found that histone H3 is a bona fide CaMKIIδB substrate and Ser-10 appears to be a predominant phosphorylation site. Increased histone H3 Ser-10 phosphorylation was observed following hypertrophic stimulation and was not associated with cellular proliferation, whereas depletion of CaMKIIδB significantly reduced histone H3 Ser-10 phosphorylation in primary cardiomyocytes. Interestingly, we found that H3 S10 phosphorylation and recruitment of CaMKIIδB occur at promoters of fetal cardiac genes. To establish the functional link between H3 phosphorylation by CaMKIIδB, chromatin remodeling and transcription activation, we developed an in vitro transcription system and using it we found that CaMKIIδB increased chromatin accessibility and mediated transcription of the Mef2 transcription factor. Conclusion: Taken together, these findings highlight a new role of CaMKIIδB as relevant histone H3 kinase and link for the first time epigenetic changes by CaMKII to cardiac hypertrophy.

scholarly journals Functional genetic encoding of sulfotyrosine in mammalian cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xinyuan He ◽  
Yan Chen ◽  
Daisy Guiza Beltran ◽  
Maia Kelly ◽  
Bin Ma ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Biochemical Characterization ◽  
Trna Synthetase ◽  
Functional Verification ◽  
Cellular Processes ◽  
Genetic Encoding ◽  
Efficient Expression

Abstract Protein tyrosine O-sulfation (PTS) plays a crucial role in extracellular biomolecular interactions that dictate various cellular processes. It also involves in the development of many human diseases. Regardless of recent progress, our current understanding of PTS is still in its infancy. To promote and facilitate relevant studies, a generally applicable method is needed to enable efficient expression of sulfoproteins with defined sulfation sites in live mammalian cells. Here we report the engineering, in vitro biochemical characterization, structural study, and in vivo functional verification of a tyrosyl-tRNA synthetase mutant for the genetic encoding of sulfotyrosine in mammalian cells. We further apply this chemical biology tool to cell-based studies on the role of a sulfation site in the activation of chemokine receptor CXCR4 by its ligand. Our work will not only facilitate cellular studies of PTS, but also paves the way for economical production of sulfated proteins as therapeutic agents in mammalian systems.

scholarly journals The role of microRNA-3085 in chondrocyte function

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Linh Le ◽  
Lingzi Niu ◽  
Matthew J. Barter ◽  
David A. Young ◽  
Tamas Dalmay ◽  
...  
Keyword(s):  
Feedback Inhibition ◽  
Interleukin 1 ◽  
Early Time ◽  
Null Cell ◽  
Time Points ◽  
Vitro Analysis ◽  
In Vitro Analysis ◽  
Cultured Chondrocytes

AbstractMicroRNAs have been shown to play a role in cartilage development, homeostasis and breakdown during osteoarthritis. We previously identified miR-3085 in humans as a chondrocyte-selective microRNA, however it could not be detected by Northern blot. The aim of the current study was to prove that miR-3085 is a microRNA and to investigate the function of miR-3085 in signaling pathways relevant to cartilage homeostasis and osteoarthritis. Here, we confirm that miR-3085 is a microRNA and not another class of small RNA using (1) a pre-miR hairpin maturation assay, (2) expression levels in a Dicer null cell line, and (3) Ago2 pulldown. MicroRNA-3085-3p is expressed more highly in micromass than monolayer cultured chondrocytes. Transfection of miR-3085-3p into chondrocytes decreases expression of COL2A1 and ACAN, both of which are validated as direct targets of miR-3085-3p. Interleukin-1 induces the expression of miR-3085-3p, at least in part via NFκB. In a feed-forward mechanism, miR-3085-3p then potentiates NFκB signaling. However, at early time points after transfection, its action appears to be inhibitory. MyD88 has been shown to be a direct target of miR-3085-3p and may be responsible for the early inhibition of NFκB signaling. However, at later time points, MyD88 knockdown remains inhibitory and so other functions of miR-3085-3p are clearly dominant. TGFβ1 also induces the expression of miR-3085-3p, but in this instance, it exerts a feedback inhibition on signaling with SMAD3 and SMAD4 shown to be direct targets. This in vitro analysis shows that miR-3085-3p functions in chondrocytes to induce IL-1-signaling, reduce TGFβ1 signaling, and inhibit expression of matrix genes. These data suggest that miR-3085-3p has a role in chondrocyte function and could contribute to the process of osteoarthritis.

scholarly journals The Ser/Thr kinase p90RSK promotes kidney fibrosis by modulating fibroblast–epithelial crosstalk

2019 ◽  
Vol 294 (25) ◽  
pp. 9901-9910 ◽  
Author(s):  
Ling Lin ◽  
Chaowen Shi ◽  
Zhaorui Sun ◽  
Nhat-Tu Le ◽  
Jun-Ichi Abe ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Nuclear Translocation ◽  
Disease Model ◽  
Kidney Fibrosis ◽  
Cellular Processes ◽  
Ribosomal Protein S6 ◽  
Forkhead Box

Healthy kidney structure and environment rely on epithelial integrity and interactions between epithelial cells and other kidney cells. The Ser/Thr kinase 90 kDa ribosomal protein S6 kinase 1 (p90RSK) belongs to a protein family that regulates many cellular processes, including cell motility and survival. p90RSK is predominantly expressed in the kidney, but its possible role in chronic kidney disease (CKD) remains largely unknown. Here, we found that p90RSK expression is dramatically activated in a classic mouse obstructive chronic kidney disease model, largely in the interstitial FSP-1–positive fibroblasts. We generated FSP-1–specific p90RSK transgenic mouse (RSK-Tg) and discovered that these mice, after obstructive injury, display significantly increased fibrosis and enhanced tubular epithelial damage compared with their wt littermates (RSK-wt), indicating a role of p90RSK in fibroblast–epithelial communication. We established an in vitro fibroblast–epithelial coculture system with primary kidney fibroblasts from RSK-Tg and RSK-wt mice and found that RSK-Tg fibroblasts consistently produce excessive H2O2 causing epithelial oxidative stress and inducing nuclear translocation of the signaling protein β-catenin. Epithelial accumulation of β-catenin, in turn, promoted epithelial apoptosis by activating the transcription factor forkhead box class O1 (FOXO1). Of note, blockade of reactive oxygen species (ROS) or β-catenin or FOXO1 activity abolished fibroblast p90RSK-mediated epithelial apoptosis. These results make it clear that p90RSK promotes kidney fibrosis by inducing fibroblast-mediated epithelial apoptosis through ROS-mediated activation of β-catenin/FOXO1 signaling pathway.

scholarly journals Overview of RNA G-quadruplex structures

2017 ◽  
Vol 63 (4) ◽  
Author(s):  
Magdalena Małgowska
Keyword(s):  
Three Dimensional ◽  
Telomere Maintenance ◽  
Structural Studies ◽  
Biological Functions ◽  
Cellular Processes ◽  
Novel Drugs ◽  
G Quadruplex ◽  
Conformational Diversity

G-quadruplexes are non-canonical secondary structures which may be formed by guanine rich sequences, both in vitro and in living cells. The number of biological functions assigned to these structural motifs has grown rapidly since the discovery of their involvement in the telomere maintenance. Knowledge of the three-dimensional structures of G-quadruplexes plays an important role in understanding their conformational diversity, physiological functions, and in the design of novel drugs targeting G-quadruplexes. For the last decades, structural studies have been mainly focused on the DNA G-quadruplexes. Their RNA counterparts gained an increased interest along with still-emerging recognition of the central role of RNA in multiple cellular processes. In this review we focus on structural properties of RNA G-quadruplexes, based on high-resolution structures, available in RCSB PDB data base and on structural models. In addition, we point out to the current challenges in this field of research.

Endothelial CSN5 impairs NF-κB activation and monocyte adhesion to endothelial cells and is highly expressed in human atherosclerotic lesions

2013 ◽  
Vol 110 (07) ◽  
pp. 141-152 ◽  
Author(s):  
Yaw Asare ◽  
Erdenechimeg Shagdarsuren ◽  
Johannes Schmid ◽  
Pathricia Tilstam ◽  
Jochen Grommes ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Umbilical Vein ◽  
Negative Regulator ◽  
Multifunctional Protein ◽  
Atherosclerotic Lesions ◽  
Tnf Α ◽  
Reporter Assays ◽  
Umbilical Vein Endothelial Cells

SummaryThe COP9 signalosome (CSN), a multifunctional protein complex involved in the regulation of cullin-RING-E3 ubiquitin ligases (CRLs), has emerged as a regulator of NF-κB signalling. As NF-κB drives the expression of pro-inflammatory and pro-atherosclerotic genes, we probed the yet unknown role of the CSN, in particular CSN5, on NF-KB-mediated atherogenic responses in endothelial cells. Co-immunoprecipitation in human umbilical vein endothelial cells (HUVECs) revealed the presence of a super-complex between IKK and CSN, which dissociates upon TNF-α stimulation. Furthermore, CSN5 silencing enhanced TNF-α-induced IKB-α degradation and NF-κB activity in luci-ferase reporter assays. This was paralleled by an increased NF-KB-driven upregulation of atherogenic chemokines and adhesion molecules, as measured by qPCR and flow cytometry, and translated into an enhanced arrest of THP-1 monocytes on TNF-α-stimulated, CSN5-depleted HUVECs. Reverse effects on NF-κB activity and THP-1 arrest were seen upon CSN5 overexpression. Finally, double-immunostaining confirmed the expression of CSN subunits in the endothelium of human atherosclerotic lesions, and revealed an increased expression of CSN5 which correlated with atheroprogression. In conclusion, endothelial CSN5 attenuates NF-KB-dependent pro-inflammatory gene expression and monocyte arrest on stimulated endothelial cells in vitro, suggesting that CSN5 might serve as a negative regulator of atherogenesis.Note: The review process for this manuscript was fully handled by G. Y. H. Lip, Editor in Chief.

Anchoring of FLT3 in the endoplasmic reticulum alters signaling quality

Blood ◽  
2009 ◽  
Vol 113 (15) ◽  
pp. 3568-3576 ◽  
Author(s):  
Dirk Schmidt-Arras ◽  
Sylvia-Annette Böhmer ◽  
Sina Koch ◽  
Jörg P. Müller ◽  
Lutz Blei ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Transformation ◽  
Intracellular Location ◽  
Er Retention ◽  
Transforming Activity ◽  
Signaling Quality

Abstract The mechanism of cell transformation by Fms-like tyrosine kinase 3 (FLT3) in acute myeloid leukemia (AML) is incompletely understood. The most prevalent activated mutant FLT3 ITD exhibits an altered signaling quality, including strong activation of the STAT5 transcription factor. FLT3 ITD has also been found partially retained as a high-mannose precursor in an intracellular compartment. To analyze the role of intracellular retention of FLT3 for transformation, we have generated FLT3 versions that are anchored in the perinuclear endoplasmic reticulum (ER) by appending an ER retention sequence containing a RRR (R3) motif. ER retention of R3, but not of corresponding A3 FLT3 versions, is shown by biochemical, fluorescence-activated cell sorting, and immunocytochemical analyses. ER anchoring reduced global autophosphorylation and diminished constitutive activation of ERK1/2 and AKT of the constitutively active FLT3 versions. ER anchoring was, however, associated with elevated signaling to STAT3. Transforming activity of the FLT3 D835Y mutant was suppressed by ER anchoring. In contrast, ER-anchored FLT3 ITD retained STAT5-activating capacity and was transforming in vitro and in vivo. The findings highlight another aspect of the different signaling quality of FLT3 ITD: It can transform cells from an intracellular location.

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