scholarly journals Genetic Interactions of the E3 Ubiquitin Ligase Component FbxA with Cyclic AMP Metabolism and a Histidine Kinase Signaling Pathway during Dictyostelium discoideum Development

2003 ◽  
Vol 2 (3) ◽  
pp. 618-626 ◽  
Author(s):  
Turgay Tekinay ◽  
Herbert L. Ennis ◽  
Mary Y. Wu ◽  
Margaret Nelson ◽  
Richard H. Kessin ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Signaling Pathway ◽  
Dictyostelium Discoideum ◽  
Ubiquitin Ligase ◽  
Histidine Kinase ◽  
Double Mutant ◽  
E3 Ubiquitin Ligase ◽  
Specific Gene ◽  
Wild Type ◽  
Camp Phosphodiesterase

ABSTRACT Dictyostelium discoideum amoebae with an altered fbxA gene, which is thought to encode a component of an SCF E3 ubiquitin ligase, have defective regulation of cell type proportionality. In chimeras with wild-type cells, the mutant amoebae form mainly spores, leaving the construction of stalks to wild-type cells. To examine the role of fbxA and regulated proteolysis, we have recovered the promoter of fbxA and shown that it is expressed in a pattern resembling that of a prestalk-specific gene until late in development, when it is also expressed in developing spore cells. Because fbxA cells are developmentally deficient in pure culture, we were able to select suppressor mutations that promote sporulation of the original mutant. One suppressor mutation resides within the gene regA, which encodes a cyclic AMP (cAMP) phosphodiesterase linked to an activating response regulator domain. In another suppressor, there has been a disruption of dhkA, a gene encoding a two-component histidine kinase known to influence Dictyostelium development. RegA appears precociously and in greater amounts in the fbxA mutant than in the wild type, but in an fbxA/dhkA double mutant, RegA is restored to wild-type levels. Because the basis of regA suppression might involve alterations in cAMP levels during development, the concentrations of cAMP in all strains were determined. The levels of cAMP are relatively constant during multicellular development in all strains except the dhkA mutant, in which it is reduced at least sixfold. The level of cAMP in the double mutant dhkA/fbxA is relatively normal. The levels of cAMP in the various mutants do not correlate with spore formation, as would be expected on the basis of our present understanding of the signaling pathway leading to the induction of spores. Altered amounts of RegA and cAMP early in the development of the mutants suggest that both fbxA and dhkA genes act earlier than previously thought.

scholarly journals The Calcineurin-FoxO-MuRF1 signaling pathway regulates myofibril integrity in cardiomyocytes

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Hirohito Shimizu ◽  
Adam D Langenbacher ◽  
Jie Huang ◽  
Kevin Wang ◽  
Georg Otto ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Ubiquitin Ligase ◽  
Degradation Mechanism ◽  
E3 Ubiquitin Ligase ◽  
Proteasome Activity ◽  
Wild Type ◽  
Structural Remodeling ◽  
Proteasome Degradation ◽  
Calcineurin Activity ◽  
Functional Deterioration

Altered Ca2+ handling is often present in diseased hearts undergoing structural remodeling and functional deterioration. However, whether Ca2+ directly regulates sarcomere structure has remained elusive. Using a zebrafish ncx1 mutant, we explored the impacts of impaired Ca2+ homeostasis on myofibril integrity. We found that the E3 ubiquitin ligase murf1 is upregulated in ncx1-deficient hearts. Intriguingly, knocking down murf1 activity or inhibiting proteasome activity preserved myofibril integrity, revealing a MuRF1-mediated proteasome degradation mechanism that is activated in response to abnormal Ca2+ homeostasis. Furthermore, we detected an accumulation of the murf1 regulator FoxO in the nuclei of ncx1-deficient cardiomyocytes. Overexpression of FoxO in wild type cardiomyocytes induced murf1 expression and caused myofibril disarray, whereas inhibiting Calcineurin activity attenuated FoxO-mediated murf1 expression and protected sarcomeres from degradation in ncx1-deficient hearts. Together, our findings reveal a novel mechanism by which Ca2+ overload disrupts myofibril integrity by activating a Calcineurin-FoxO-MuRF1-proteosome signaling pathway.

scholarly journals The Calcineurin-FoxO-MuRF1 Signaling Pathway Regulates Myofibril Integrity in Cardiomyocytes

2017 ◽  
Author(s):  
Hirohito Shimizu ◽  
Adam Langenbacher ◽  
Jie Huang ◽  
Kevin Wang ◽  
Georg W. Otto ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Ubiquitin Ligase ◽  
Degradation Mechanism ◽  
E3 Ubiquitin Ligase ◽  
Wild Type ◽  
Zebrafish Model ◽  
Heart Muscle Cells ◽  
Profiling Analysis ◽  
Calcineurin Activity ◽  
Functional Deterioration

AbstractAltered Ca2+ handling is often present in diseased hearts undergoing structural remodeling and functional deterioration. The influences of Ca2+ signaling on cardiac function have been examined extensively, but whether Ca2+ directly regulates sarcomere structure has remained elusive. Using a mutant zebrafish model lacking NCX1 activity in the heart, we explored the impacts of impaired Ca2+ homeostasis on myofibril integrity. Gene expression profiling analysis revealed that the E3 ubiquitin ligase MuRF1 is upregulated in ncx1-deficient hearts. Intriguingly, knocking down MuRF1 activity or inhibiting proteasome activity preserved myofibril integrity in ncx1 deficient hearts, revealing a MuRF1-mediated proteasome degradation mechanism that is activated in response to abnormal Ca2+ homeostasis. Furthermore, we detected an accumulation of the MuRF1 regulator FoxO in the nuclei of ncx1-deficient cardiomyocytes. Overexpression of FoxO in wild type cardiomyocytes induced MuRF1 expression and caused myofibril disarray, whereas inhibiting Calcineurin activity attenuated FoxO-mediated MuRF1 expression and protected sarcomeres from degradation in ncx1-deficient hearts. Together, our findings reveal a novel mechanism by which Ca2+ overload disrupts the myofibril integrity in heart muscle cells by activating a Calcineurin-FoxO-MuRF1-proteosome signaling pathway.

scholarly journals A Putative Ariadne-Like Ubiquitin Ligase Is Required for Dictyostelium discoideum Development

2006 ◽  
Vol 5 (10) ◽  
pp. 1820-1825 ◽  
Author(s):  
Nathaniel Whitney ◽  
Lacey J. Pearson ◽  
Ryan Lunsford ◽  
Lisa McGill ◽  
Richard H. Gomer ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Ubiquitin Ligase ◽  
Fruiting Bodies ◽  
Wild Type ◽  
Cell Numbers

ABSTRACT The Dictyostelium rbrA gene encodes a putative Ariadne ubiquitin ligase. rbrA − cells form defective slugs that cannot phototax. Prestalk cell numbers are reduced in rbrA − slugs, and these prestalk cells do not localize to the tip of slugs. Chimeric slugs containing wild-type cells could phototax and form fruiting bodies.

scholarly journals Functional Promiscuity of Gene Regulation by Serpentine Receptors in Dictyostelium discoideum

1998 ◽  
Vol 18 (10) ◽  
pp. 5744-5749 ◽  
Author(s):  
Irene Verkerke-Van Wijk ◽  
Ji-Yun Kim ◽  
Raymond Brandt ◽  
Peter N. Devreotes ◽  
Pauline Schaap
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Dictyostelium Discoideum ◽  
Developmental Regulation ◽  
Mutant Cell ◽  
Gene Induction ◽  
Specific Gene ◽  
Wild Type ◽  
Animal Development ◽  
Camp Stimulation

ABSTRACT Serpentine receptors such as smoothened and frizzled play important roles in cell fate determination during animal development. InDictyostelium discoideum, four serpentine cyclic AMP (cAMP) receptors (cARs) regulate expression of multiple classes of developmental genes. To understand their function, it is essential to know whether each cAR is coupled to a specific gene regulatory pathway or whether specificity results from the different developmental regulation of individual cARs. To distinguish between these possibilities, we measured gene induction in car1 car3 double mutant cell lines that express equal levels of either cAR1, cAR2, or cAR3 under a constitutive promoter. We found that all cARs efficiently mediate both aggregative gene induction by cAMP pulses and induction of postaggregative and prespore genes by persistent cAMP stimulation. Two exceptions to this functional promiscuity were observed. (i) Only cAR1 can mediate adenosine inhibition of cAMP-induced prespore gene expression, a phenomenon that was found earlier in wild-type cells. cAR1’s mediation of adenosine inhibition suggests that cAR1 normally mediates prespore gene induction. (ii) Only cAR2 allows entry into the prestalk pathway. Prestalk gene expression is induced by differentiation-inducing factor (DIF) but only after cells have been prestimulated with cAMP. We found that DIF-induced prestalk gene expression is 10 times higher in constitutive cAR2 expressors than in constitutive cAR1 or cAR3 expressors (which still have endogenous cAR2), suggesting that cAR2 mediates induction of DIF competence. Since in wild-type slugs cAR2 is expressed only in anterior cells, this could explain the so far puzzling observations that prestalk cells differentiate at the anterior region but that DIF levels are actually higher at the posterior region. After the initial induction of DIF competence, cAMP becomes a repressor of prestalk gene expression. This function can again be mediated by cAR1, cAR2, and cAR3.

Action of a slowly hydrolysable cyclic AMP analogue on developing cells of Dictyostelium discoideum

1979 ◽  
Vol 35 (1) ◽  
pp. 321-338
Author(s):  
C. Rossier ◽  
G. Gerisch ◽  
D. Malchow
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Agar Plate ◽  
Cell Aggregation ◽  
Fruiting Bodies ◽  
Wild Type ◽  
Camp Analogue ◽  
Order Of Magnitude

Adenosine 3′,5′-cyclic phosphorothioate (cAMP-S) is a cyclic AMP (cAMP) analogue which is only slowly hydrolysed by phosphodiesterases of Dictyostelium discoideum. The affinity of cAMP-S to cAMP receptors at the cell surface is only one order of magnitude lower than that of cAMP. cAMP-S can replace cAMP as a stimulant with respect to all receptor-mediated responses tested, including chemotaxis and the induction of cAMP pulses. cAMP-S does not affect growth of D. discoideum but it blocks cell aggregation at a uniform concentration of 5 × 10(−7) M in agar plate cultures of strain NC-4 as well as its axenically growing derivative, Ax-2. Another wild-type strain of D. discoideum, v-12, is able to aggregate on agar plates supplemented with 1 mM cAMP-S. The development of Polysphondylium pallidum and P. violaceum is also highly cAMP-S resistant. In Ax-2 both differentiation from the growth phase to the aggregation-competent stage and chemotaxis are cAMP-S sensitive, whereas in v-12 only chemotaxis is inhibited. v-12 can still form streams of cohering cells and fruiting bodies when chemotaxis is inhibited by cAMP-S. Whereas cAMP induces differentiation into stalk cells at concentrations of 10(−3) or 10(−4) M, cAMP-S has the same effect in strain v-12 at the much lower concentration of 10(−6) M.

E3 ubiquitin ligase TRIM7 negatively regulates NF-kappa B signaling pathway by degrading p65 in lung cancer

2020 ◽  
Vol 69 ◽  
pp. 109543 ◽  
Author(s):  
Jiangbo Jin ◽  
Zhuo Lu ◽  
Xiaomei Wang ◽  
Yufeng Liu ◽  
Tianyu Han ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Signaling Pathway ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Nf Kappa B

scholarly journals Cross Talk between the Cell Wall Integrity and Cyclic AMP/Protein Kinase A Pathways in Cryptococcus neoformans

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Maureen J. Donlin ◽  
Rajendra Upadhya ◽  
Kimberly J. Gerik ◽  
Woei Lam ◽  
Laura G. VanArendonk ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Cryptococcus Neoformans ◽  
Signaling Pathway ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Content Type ◽  
Kinase A

ABSTRACTCryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work has shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely,PKC1,BCK1,MKK2, andMPK1results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors, and for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional responses to gene deletions ofBCK1,MKK2, andMPK1compared to wild-type cells. We found that over 1,000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion strains revealed significantly less cAMP in all of the deletion strains compared to the wild-type strain. The deletion strains also produced significantly smaller capsules than the wild-type KN99 strain did under capsule-inducing conditions, although the levels of capsule they shed were similar to those shed by the wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to levels near those of wild type. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis.IMPORTANCECryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall are primarily controlled by the cell wall integrity (CWI) signaling pathway. In this study, we demonstrate that deletion of any of three core kinases in the CWI pathway impacts not only the cell wall but also the amount of surface capsule. Deletion of any of the kinases results in significantly reduced cellular cyclic AMP (cAMP) levels, and addition of exogenous cAMP rescues the capsule defect and some cell wall defects, supporting a direct role for the CWI pathway in regulation of capsule in conjunction with the cAMP/protein kinase A pathway.

The Cbl E3 Ubiquitin Ligase Negatively Regulates Erythropoiesis through Expression of the Foxo3a Transcription Factor.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1374-1374
Author(s):  
Terri D Richmond ◽  
Monica L Bailey ◽  
Wallace Y Langdon ◽  
Dwayne Barber
Keyword(s):  
Signal Transduction ◽  
Cell Signaling ◽  
Ubiquitin Ligase ◽  
Knockout Mice ◽  
E3 Ubiquitin Ligase ◽  
Parp Cleavage ◽  
Signal Transduction Pathways ◽  
Wild Type ◽  
Erythroid Progenitors ◽  
Deficient Mice

Abstract Erythropoietin (EPO) is the primary cytokine regulator of red blood cell (RBC) progenitor growth, survival and differentiation. EPO stimulation is regulated by EPO binding to its cognate ligand, the EPO receptor (EPO-R), and activating the primary associated tyrosine kinase, JAK2. The critical importance of EPO, EPO-R and JAK2 to erythropoiesis is demonstrated by the fatal embryonic anemia that develops upon EPO, EPO-R or JAK2 deletion. Intracellular signal transduction pathways regulating growth, survival and differentiation downstream of the EPO-R and JAK2 are well documented. However, relatively little is known about down-regulation of EPO-R signal transduction pathways at this time. Our laboratory has previously demonstrated that EPO stimulation leads to Cbltyrosine phosphorylation and subsequent recruitment of Crk-C3G, leading to Rap1activation. In addition, Cbl serves as an adaptor protein linking to PI 3 kinase and Rasand targets receptor tyrosine kinases for ubiquitination and proteasomal degradation. Cbl knockout mice have been generated and have defects in stem and T cell signaling pathways. Elevated platelet numbers and splenomegaly was observed, suggesting that Cbl −/− mice may have defects in megakaryocyte/erythroid progenitors or more committed cells in each lineage. The objective of this studyis to determine whether Cbl affects erythropoiesis and EPO-dependent signaling. Resting Cbl −/− mice (in the C57Bl/6 background) have increased numbers of Burst Forming Unit-Erythroid and Colony Forming Unit-Erythroid (CFU-E) cells. Furthermore, there is a 3-fold elevation of splenic CFU-E numbers. Erythroid differentiation was monitored via expression of the Transferrin Receptor (CD71) and Ter119. Cbl-deficient mice have delayed differentiation in the bone marrow with diminished CD71-Ter119+ cells. Increased apoptosis is observed in Ter119+ erythroid cells isolated from Cbl −/− mice as determined by Annexin V staining and confirmed by increased PARP cleavage. Interestingly, reactive oxygen species in wild type and Cbl-deficient mice remain unchanged. Despite normal resting hematologic parameters, serum EPO concentrations are elevated in Cbl knockout mice. Serum VEGF levels are comparable between wild type and Cbl −/− mice, suggesting that the EPO effect is specific to the erythroid lineage and not an effect of hypoxia. Notable differences in wild type and Cbl −/− mice were observed when stress erythropoiesiswas induced by phenylhydrazine-mediated anemia. Cbl-deficient mice respond with enhanced hematocrit recovery and increased reticulocyte production. EPO-dependent Aktphosphorylation is hypersensitive in Cbl −/− splenic erythroblasts. Interestingly, expression ofFoxo3a was stabilized in Cbl −/− splenic erythroblasts, suggesting that Cbl degrades Foxo3a in a direct or indirect manner. Given the importance of Foxo3a in regulating erythropoiesis, we are currently determining whether Cbl targets Foxo3a for ubiquitin-mediated degradation. These data demonstrate the remarkable homeostatic ability of the mouse to retain normal RBC concentrations in the peripheral blood despite elevated erythroid progenitors and cell signaling. Importantly, these studies are the first to phenotypically explore the effects of genetic ablation of an EPO-responsive E3 ubiquitin ligase in erythropoiesis.

Unique Gain-of-Function of Mutated c-CBL Tumor Suppresor in Myeloid Neoplasms.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2970-2970
Author(s):  
Masashi Sanada ◽  
Takahiro Suzuki ◽  
Lee-Yung Shih ◽  
Makoto Otsu ◽  
Motohiro Kato ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Tyrosine Kinases ◽  
E3 Ubiquitin Ligase ◽  
Tumour Suppressor ◽  
Wild Type ◽  
Gain Of Function ◽  
Hematopoietic Stem ◽  
Myeloid Neoplasms ◽  
Ubiquitin Ligase Activity ◽  
Type C

Abstract Abstract 2970 Poster Board II-946 Acquired uniparental disomy (aUPD) is a common feature of myeloid neoplasms, especially myelodysplastic syndromes (MDS) / myeloploriferative neoplasms (MPN). aUPDs preferentially affected several chromosomal arms in distinct subsets of patients, and frequently associated with mutated oncogenes and tumour suppressor genes. Among these, the most common aUPDs are those involving 11q, which defined a unique subset of myeloid neoplasms that were clinically characterized by frequent diagnosis of chronic myelomonocytic leukaemia (CMML) with normal karyotypes. Recently, we and other groups reported that 11qUPD are genetically defined by the presence of homozygous mutations of C-CBL. C-CBL proto-oncogene is the cellular homolog of the v-Cbl transforming gene of the Cas NS-1 murine leukemia virus. C-CBL is thought to be involved in the negative modulation of tyrosine kinase signalling, primarily through their E3 ubiquitin ligase activity that is responsible for the down-regulation of activated tyrosine kinases. As expected from the latter function, we demonstrated that wild-type C-CBL has tumour suppressor functions; c-Cbl null mice showed expanded hematopoietic progenitor pools, promoted blastic crisis induced by a bcr/abl transgene, and spontaneous development of late-onset invasive cancers in complete penetrance. On the other hand, mutated C-CBL showed clear oncogenic potential; all tested mutants strongly transformed NIH3T3 fibroblasts, and prolonged replating capacity of hematopoietic progenitors. All reported C-CBL mutations involved the linker-RING finger domains that are central to the E3 ubiquitin ligase activity. We demonstrated that mutated C-CBL not only lost their E3 ubiquitin ligase activity, but also inhibited that of wild-type C-CBL, leading to prolonged activation of a broad spectrum of tyrosine kinases after ligand stimulations in fibroblasts and hematopoietic cells. In accordance with this, c-Cbl−/− hematopoietic stem/progenitor cells (HSPCs) showed enhanced sensitivity to a variety of cytokines, but unexpectedly, transduction of C-CBL mutants into c-Cbl−/− HSPCs further augmented the sensitivity to a broader spectrum of cytokines, indicating the presence of gain-of-function in mutated C-CBL that is not simply mediated by inhibition of wild-type C-CBL functions. The gain-of-function effects of C-CBL mutants on cytokine sensitivity of HSPCs largely disappeared in the c-Cbl+/+ background or by co-transduction of wild-type C-CBL, which may suggest the pathogenic importance of loss of wild-type c-Cbl alleles found in most cases of C-CBL-mutated myeloid neoplasms. Our findings provide a novel insight into a role of gain-of-function mutations of a tumour suppressor associated with aUPD in the pathogenesis of some of myeloid cancer subsets. Currently, further functional studies regarding the molecular mechanism of the gain-of-function are ongoing. Disclosures: Omine: Alexion: Consultancy, Research Funding.

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