Structure and Function of the Urokinase Receptor

1999 ◽  
Vol 82 (S 01) ◽  
pp. 19-22 ◽  
Author(s):  
Massimo Resnati ◽  
Anna Mondino ◽  
Francesco Blasi
Keyword(s):  
Conformational Change ◽  
Tyrosine Kinases ◽  
High Efficiency ◽  
Cytoskeletal Organization ◽  
Surface Molecules ◽  
Experimental Systems ◽  
Recombinant Receptor ◽  
A Cell ◽  
And Function

SummaryThe binding of the urokinase plasminogen activator (uPA) to its receptor (uPAR) regulates cell adhesion, surface proteolysis, chemotaxis and cell extravasation in a number of experimental systems. Recent evidences have suggested that uPAR can by itself mediate chemotaxis of human monocytes and cause profound changes in cytoskeletal organization indicating that this receptor has the properties of a cell-surface regulated chemokine. Indeed, it is likely that upon binding to uPA, uPAR undergoes a conformational change that uncovers a new epitope located in the linker region between domain 1 and 2 of the receptor and is endowed with a potent chemotactic activity. This conformational change can be mimicked in vitro by enzymatic processing of a recombinant receptor. We have shown that chymotrypsin cleaves uPAR between domain 1 and 2 in an area that can be also cleaved by uPA at high efficiency and generate a receptor that can mediate monocytes migration independently of uPA binding. This mechanism is pertussis-toxin sensitive and involves activation of tyrosine kinases and cytoskeletal reorganization events in vitro. These studies indicate that in addition to its receptor function, upon binding to uPA, uPAR becomes a pleiotropic ligand for other still to be identified surface molecules.

scholarly journals BHLHE40 Regulates IL-10 and IFN-γ Production in T Cells but Does Not Interfere With Human Type 1 Regulatory T Cell Differentiation

2021 ◽  
Vol 12 ◽  
Author(s):  
Molly Javier Uyeda ◽  
Robert A. Freeborn ◽  
Brandon Cieniewicz ◽  
Rosa Romano ◽  
Ping (Pauline) Chen ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
Ex Vivo ◽  
Surface Expression ◽  
Surface Molecules ◽  
Ifn Γ ◽  
And Function ◽  
Tr1 Cells

Type 1 regulatory T (Tr1) cells are subset of peripherally induced antigen-specific regulatory T cells. IL-10 signaling has been shown to be indispensable for polarization and function of Tr1 cells. However, the transcriptional machinery underlying human Tr1 cell differentiation and function is not yet elucidated. To this end, we performed RNA sequencing on ex vivo human CD49b+LAG3+ Tr1 cells. We identified the transcription factor, BHLHE40, to be highly expressed in Tr1 cells. Even though Tr1 cells characteristically produce high levels of IL-10, we found that BHLHE40 represses IL-10 and increases IFN-γ secretion in naïve CD4+ T cells. Through CRISPR/Cas9-mediated knockout, we determined that IL10 significantly increased in the sgBHLHE40-edited cells and BHLHE40 is dispensable for naïve CD4+ T cells to differentiate into Tr1 cells in vitro. Interestingly, BHLHE40 overexpression induces the surface expression of CD49b and LAG3, co-expressed surface molecules attributed to Tr1 cells, but promotes IFN-γ production. Our findings uncover a novel mechanism whereby BHLHE40 acts as a regulator of IL-10 and IFN-γ in human CD4+ T cells.

Control of N-cadherin-mediated intercellular adhesion in migrating neural crest cells in vitro

1995 ◽  
Vol 108 (12) ◽  
pp. 3839-3853 ◽  
Author(s):  
F. Monier-Gavelle ◽  
J.L. Duband
Keyword(s):  
Neural Crest ◽  
Tyrosine Kinases ◽  
Brefeldin A ◽  
Neural Crest Cells ◽  
Cell Aggregation ◽  
Phosphatase Inhibitors ◽  
Intercellular Contacts ◽  
And Function ◽  
Cell Cell

Dispersion of neural crest cells and their ultimate regroupment into peripheral ganglia are associated with precisely coordinated regulations both in time and space of the expression and function of cell adhesion receptors. In particular, the disappearance of N-cadherin from the cell surface at the onset of migration and its reexpression during cell aggregation suggest that, during migration, N-cadherin expression is repressed in neural crest cells. In the present study, we have analyzed in vitro the mechanism of control of N-cadherin expression and function in migrating neural crest cells. Although these cells moved as a dense population, each individual did not establish extensive and permanent intercellular contacts with its neighbors. However, cells synthesized and expressed mature N-cadherin molecules at levels comparable to those found in cells that exhibit stable intercellular contacts, but in contrast to them, the bulk of N-cadherin molecules was not connected with the cytoskeleton. We next determined which intracellular events are responsible for the instability of the N-cadherin junctions in neural crest cells using various chemical agents known to affect signal transduction processes. Agents that block a broad spectrum of serine-threonine kinases (6-dimethylaminopurine, H7 and staurosporine) or that affect selectively protein kinases C (bisindolylmaleimide and sphingosine), inhibitors of protein tyrosine kinases (erbstatin, herbimycin A, and tyrphostins), and inhibitors of phosphatases (vanadate) all restored tight cell-cell associations among neural crest cells, accompanied by a slight increase in the overall cellular content of N-cadherin and its accumulation to the regions of intercellular contacts. The effect of the kinase and phosphatase blockers was inhibitable by agents known to affect protein synthesis (cycloheximide) and exportation (brefeldin A), indicating that the restored cell-cell contacts were mediated chiefly by an intracellular pool of N-cadherin molecules recruited to the membrane. Finally, N-cadherin molecules were constitutively phosphorylated in migrating neural crest cells, but their level and state of phosphorylation were apparently not modified in the presence of kinase and phosphatase inhibitors. These observations therefore suggest that N-cadherin-mediated cell-cell interactions are not stable in neural crest cells migrating in vitro, and that they are under the control of a complex cascade of intracellular signals involving kinases and phosphatases and probably elicited by surface receptors.

scholarly journals Intramolecular regulation of anillin during cytokinesis

2019 ◽  
Author(s):  
Daniel Beaudet ◽  
Nhat Pham ◽  
Noha Skaik ◽  
Alisa Piekny
Keyword(s):  
Conformational Change ◽  
Binding Domain ◽  
C2 Domain ◽  
A Cell ◽  
And Function

ABSTRACTCytokinesis occurs by the ingression of an actomyosin ring that cleaves a cell into two daughters. This process is tightly controlled to avoid aneuploidy, and we previously showed that active Ran coordinates ring positioning with chromatin. Active Ran is high around chromatin, and forms an inverse gradient to cargo-bound importins. We found that the ring component anillin contains an NLS that binds to importin and is required for its function. Anillin contains a RhoA-binding domain (RBD), which we revealed autoinhibits the adjacent NLS-containing C2 domain. Here, we show that active RhoA relieves inhibition of the C2 domain. Furthermore, FRAP experiments show that the NLS regulates anillin’s cortical properties, supporting feedback to the RBD. Indeed, mutations that disrupt the interface between the RBD and C2 domain disrupt anillin’s localization and function. Thus, active RhoA induces a conformational change that increases accessibility to the C2 domain, which is maintained by importin-binding for recruitment to the equatorial cortex.

scholarly journals Expression and Function of Murine Receptor Tyrosine Kinases, TIE and TEK, in Hematopoietic Stem Cells

Blood ◽  
1997 ◽  
Vol 89 (12) ◽  
pp. 4317-4326 ◽  
Author(s):  
Michihiro Yano ◽  
Atsushi Iwama ◽  
Hitoshi Nishio ◽  
Junko Suda ◽  
Goro Takada ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Stem Cell Marker ◽  
Proliferative Potential ◽  
Hematopoietic Stem ◽  
And Function

Abstract Two highly related receptor tyrosine kinases, TIE and TEK, comprise a family of endothelial cell-specific kinase. We established monoclonal antibodies against them and performed detailed analyses on their expression and function in murine hematopoietic stem cells (HSCs). TIE and TEK were expressed on 23.7% and 33.3% of lineage marker-negative, c-Kit+ and Sca-1+ (Lin− c-Kit+ Sca-1+) HSCs that contain the majority of day-12 colony-forming units-spleen (CFU-S) and long-term reconstituting cells, but not committed progenitor cells. Lin− c-Kit+ Sca-1+ cells were further divided by the expression of TIE and TEK. TIE+ and TEK+ HSCs as well as each negative counterpart contained high proliferative potential colony-forming cells and differentiated into lymphoid and myeloid progenies both in vitro and in vivo. However, day-12 CFU-S were enriched in TIE+ and TEK+ HSCs. Our findings define TIE and TEK as novel stem cell marker antigens that segregate day-12 CFU-S, and provide evidence of novel signaling pathways that are involved in the functional regulation of HSCs at a specific stage of differentiation, particularly of day-12 CFU-S.

scholarly journals Comparison of tyrosine kinase domain properties for the neurotrophin receptors TrkA and TrkB

2020 ◽  
Vol 477 (20) ◽  
pp. 4053-4070
Author(s):  
Stephen C. Artim ◽  
Anatoly Kiyatkin ◽  
Mark A. Lemmon
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Catalytic Efficiency ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Signaling Dynamics ◽  
Cellular Context ◽  
And Function ◽  
High Degree

The tropomyosin-related kinase (Trk) family consists of three receptor tyrosine kinases (RTKs) called TrkA, TrkB, and TrkC. These RTKs are regulated by the neurotrophins, a class of secreted growth factors responsible for the development and function of neurons. The Trks share a high degree of homology and utilize overlapping signaling pathways, yet their signaling is associated with starkly different outcomes in certain cancers. For example, in neuroblastoma, TrkA expression and signaling correlates with a favorable prognosis, whereas TrkB is associated with poor prognoses. To begin to understand how activation of the different Trks can lead to such distinct cellular outcomes, we investigated differences in kinase activity and duration of autophosphorylation for the TrkA and TrkB tyrosine kinase domains (TKDs). We find that the TrkA TKD has a catalytic efficiency that is ∼2-fold higher than that of TrkB, and becomes autophosphorylated in vitro more rapidly than the TrkB TKD. Studies with mutated TKD variants suggest that a crystallographic dimer seen in many TrkA (but not TrkB) TKD crystal structures, which involves the kinase-insert domain, may contribute to this enhanced TrkA autophosphorylation. Consistent with previous studies showing that cellular context determines whether TrkB signaling is sustained (promoting differentiation) or transient (promoting proliferation), we also find that TrkB signaling can be made more transient in PC12 cells by suppressing levels of p75NTR. Our findings shed new light on potential differences between TrkA and TrkB signaling, and suggest that subtle differences in signaling dynamics can lead to substantial shifts in the cellular outcome.

scholarly journals Conformational changes induced in the protein tyrosine kinase p72syk by tyrosine phosphorylation or by binding of phosphorylated immunoreceptor tyrosine-based activation motif peptides.

1996 ◽  
Vol 16 (4) ◽  
pp. 1471-1478 ◽  
Author(s):  
T Kimura ◽  
H Sakamoto ◽  
E Appella ◽  
R P Siraganian
Keyword(s):  
Tyrosine Phosphorylation ◽  
Conformational Change ◽  
Conformational Changes ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Critical Event ◽  
Protein Tyrosine ◽  
Intracellular Signals ◽  
Activation Motif

A critical event in signaling in immune cells is the interaction of Syk or ZAP-70 protein tyrosine kinases with multisubunit receptors that contain an approximately 18-amino-acid domain called the immunoreceptor tyrosine-based activation motif (ITAM). Tyrosine-phosphorylated Syk from activated cells was in a conformation different from that in nonstimulated cells as demonstrated by changes in immunoreactivity. The addition of tyrosine-diphosphorylated ITAM peptides resulted in a similar conformational change in Syk from nonactivated cells. The peptides based on FcepsilonRIgamma were more active than those based on Fcepsilon RIbeta. In vitro autophosphorylation of Syk was dramatically enhanced by the addition of the diphosphorylated ITAM peptides. The conformational change and the enhanced autophosphorylation required the presence of both phosphorylated tyrosines on the same molecule. These conformational changes in Syk by tyrosine phosphorylation or binding to diphosphorylated ITAM could be critical for Syk activation and downstream propagation of intracellular signals.

Imatinib mesylate affects the development and function of dendritic cells generated from CD34+ peripheral blood progenitor cells

Blood ◽  
2004 ◽  
Vol 103 (2) ◽  
pp. 538-544 ◽  
Author(s):  
Silke Appel ◽  
Andreas M. Boehmler ◽  
Frank Grünebach ◽  
Martin R. Müller ◽  
Anette Rupf ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Progenitor Cells ◽  
Imatinib Mesylate ◽  
Tyrosine Kinases ◽  
Kinase Inhibitor ◽  
Hematopoietic Cells ◽  
Signal Transduction Pathway ◽  
Myelogenous Leukemia ◽  
And Function

Abstract Imatinib mesylate (STI571) is a competitive Bcr-Abl tyrosine kinase inhibitor and has yielded encouraging results in treatment of chronic myelogenous leukemia (CML) and gastrointestinal stroma tumors (GISTs). Apart from inhibition of the Abl protein tyrosine kinases, it also shows activity against platelet-derived growth factor receptor (PDGF-R), c-Kit, Abl-related gene (ARG), and their fusion proteins while sparing other kinases. In vitro studies have revealed that imatinib mesylate can inhibit growth of cell lines and primitive malignant progenitor cells in CML expressing Bcr-Abl. However, little is known about the effects of imatinib mesylate on nonmalignant hematopoietic cells. In the current study we demonstrate that in vitro exposure of mobilized human CD34+ progenitors to therapeutic concentrations of imatinib mesylate (1-5 μM) inhibits their differentiation into dendritic cells (DCs). DCs obtained after 10 to 16 days of culture in the presence of imatinib mesylate showed concentration-dependent reduced expression levels of CD1a and costimulatory molecules such as CD80 and CD40. Furthermore, exposure to imatinib mesylate inhibited the induction of primary cytotoxic T-lymphocyte (CTL) responses. The inhibitory effects of imatinib mesylate were accompanied by down-regulation of nuclear localized RelB protein. Our results demonstrate that imatinib mesylate can act on normal hematopoietic cells and inhibits the differentiation and function of DCs, which is in part mediated via the nuclear factor κB signal transduction pathway.

scholarly journals Versatility of Reverse Micelles: From Biomimetic Models to Nano (Bio)Sensor Design

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 345
Author(s):  
Melania-Liliana Arsene ◽  
Iuliana Răut ◽  
Mariana Călin ◽  
Maria-Luiza Jecu ◽  
Mihaela Doni ◽  
...  
Keyword(s):  
Reverse Micelles ◽  
High Efficiency ◽  
Supramolecular Organization ◽  
Sensor Design ◽  
Artificial System ◽  
Synthesis Of Nanoparticles ◽  
Biological Studies ◽  
The Status ◽  
A Cell

This paper presents an overview of the principal structural and dynamics characteristics of reverse micelles (RMs) in order to highlight their structural flexibility and versatility, along with the possibility to modulate their parameters in a controlled manner. The multifunctionality in a large range of different scientific fields is exemplified in two distinct directions: a theoretical model for mimicry of the biological microenvironment and practical application in the field of nanotechnology and nano-based sensors. RMs represent a convenient experimental approach that limits the drawbacks of the conventionally biological studies in vitro, while the particular structure confers them the status of simplified mimics of cells by reproducing a complex supramolecular organization in an artificial system. The biological relevance of RMs is discussed in some particular cases referring to confinement and a crowded environment, as well as the molecular dynamics of water and a cell membrane structure. The use of RMs in a range of applications seems to be more promising due to their structural and compositional flexibility, high efficiency, and selectivity. Advances in nanotechnology are based on developing new methods of nanomaterial synthesis and deposition. This review highlights the advantages of using RMs in the synthesis of nanoparticles with specific properties and in nano (bio)sensor design.

scholarly journals Myelin-associated glycoprotein, a cell adhesion molecule of oligodendrocytes, is phosphorylated in brain.

1988 ◽  
Vol 8 (6) ◽  
pp. 2655-2658 ◽  
Author(s):  
A M Edwards ◽  
M Arquint ◽  
P E Braun ◽  
J C Roder ◽  
R J Dunn ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Cell Adhesion Molecule ◽  
Protein Tyrosine Kinases ◽  
Developmentally Regulated ◽  
Myelin Membrane ◽  
Tyrosine Residues ◽  
A Cell ◽  
Myelin Associated Glycoprotein

Myelin-associated glycoprotein (MAG) has been implicated in the mediation of interactions between oligodendrocytes and neurons during the development of the myelin sheath. Here we show that MAG is phosphorylated in intact myelinating mouse brain primarily at serine residues and to a lesser extent at threonine and tyrosine residues. In vivo, only the larger of the two developmentally regulated MAG isoforms is phosphorylated. MAG can be phosphorylated at tyrosine by the v-fps and v-src protein-tyrosine kinases in vitro and by a kinase endogenous to myelin membrane preparations. MAG phosphorylated in myelin membranes in vitro also contains phosphoserine and phosphothreonine. These observations suggest that phosphorylation of MAG is physiologically significant in regulating oligodendrocyte-neuron interactions.

scholarly journals Effect of nucleoside triphosphate and magnesium ion concentration on the stability and function of rat liver polysomes in vitro

1968 ◽  
Vol 110 (4) ◽  
pp. 783-788 ◽  
Author(s):  
A. W. Pronczuk ◽  
B. S. Baliga ◽  
H. N. Munro
Keyword(s):  
Rat Liver ◽  
Ion Concentration ◽  
Nucleoside Triphosphate ◽  
Free Protein ◽  
A Cell ◽  
The Stability ◽  
And Function ◽  
Polysome Stability ◽  
Hydrolysis Of

The effects of different concentrations of ATP, GTP, UTP and CTP on polysome stability and function in a cell-free protein-synthesizing system prepared from rat liver were studied. Increasing the concentration of ATP in the incubation medium to 15mm resulted in progressive disaggregation of the polysomes; at ATP concentrations above 2mm their capacity to incorporate amino acids into peptide chains diminished. The same disaggregation phenomenon could be produced by incubating polysomes in a buffered medium containing 5mm-Mg2+ and increasing concentrations of ATP. Although the disaggregating action of ATP could be prevented by increasing Mg2+ concentration, the amino acid incorporation in the cell-free protein-synthesizing system remained impaired. The effects of different concentrations of GTP, UTP and CTP on polysome stability were similar to those of ATP. Increasing the concentrations of each nucleoside triphosphate also inhibited the hydrolysis of GTP in the cell-free protein-synthesizing system.

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