scholarly journals Peptidyl-Prolyl Isomerase 1 (Pin1) Serves as a Coactivator of Steroid Receptor by Regulating the Activity of Phosphorylated Steroid Receptor Coactivator 3 (SRC-3/AIB1)

2005 ◽  
Vol 25 (21) ◽  
pp. 9687-9699 ◽  
Author(s):  
Ping Yi ◽  
Ray-Chang Wu ◽  
Joshua Sandquist ◽  
Jiemin Wong ◽  
Sophia Y. Tsai ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Intracellular Signaling ◽  
Steroid Receptors ◽  
Steroid Receptor ◽  
Dependent Manner ◽  
Prolyl Isomerase ◽  
Peptidyl Prolyl Isomerase ◽  
Steroid Receptor Coactivator

ABSTRACT Steroid receptor coactivator 3 (SRC-3/AIB1) interacts with steroid receptors in a ligand-dependent manner to activate receptor-mediated transcription. A number of intracellular signaling pathways initiated by growth factors and hormones induce phosphorylation of SRC-3, regulating its function and contributing to its oncogenic potential. However, the range of mechanisms by which phosphorylation affects coactivator function remains largely undefined. We demonstrate here that peptidyl-prolyl isomerase 1 (Pin1), which catalyzes the isomerization of phosphorylated Ser/Thr-Pro peptide bonds to induce conformational changes of its target proteins, interacts selectively with phosphorylated SRC-3. In addition, Pin1 and SRC-3 activate nuclear-receptor-regulated transcription synergistically. Depletion of Pin1 by small interfering RNA (siRNA) reduces hormone-dependent transcription from both transfected reporters and an endogenous steroid receptor target gene. We present evidence that Pin1 modulates interactions between SRC-3 and CBP/p300. The interaction is enhanced in vitro and in vivo by Pin1 and diminished when cellular Pin1 is reduced by siRNA or in stable Pin1-depleted cell lines. Depletion of Pin1 in MCF-7 human breast cancer cells reduces the endogenous estrogen-dependent recruitment of p300 to the promoters of estrogen receptor-dependent genes. Pin1 overexpression enhanced SRC-3 cellular turnover, and depletion of Pin1 stabilized SRC-3. Our results suggest that Pin1 functions as a transcriptional coactivator of nuclear receptors by modulating SRC-3 coactivator protein-protein complex formation and ultimately by also promoting the turnover of the activated SRC-3 oncoprotein.

Steroid receptor coactivator-1 regulates glioma angiogenesis through polyomavirus enhancer activator 3 signaling

2019 ◽  
Vol 97 (4) ◽  
pp. 488-496
Author(s):  
Yi Zhang ◽  
Wei Shi
Keyword(s):  
Endothelial Cell ◽  
Growth Factor ◽  
Steroid Receptors ◽  
Glioma Cells ◽  
Steroid Receptor ◽  
Angiogenic Factors ◽  
Endothelial Cell Migration ◽  
Steroid Receptor Coactivator

Steroid receptor coactivator 1 (SRC-1) is a transcriptional coactivator for steroid receptors and other transcription factors. SRC-1 has been shown to play an important role in the progression of breast cancer and prostate cancer. However, its role in glioma progression remains unknown. Here, in this study, we report that SRC-1 is upregulated in the vessels of human glioma and exerts important regulatory functions. Specifically, SRC-1 expression significantly enhanced basic fibroblast growth factor (bFGF)-mediated angiogenesis in vivo. Downregulating of SRC-1 expression suppressed endothelial cell migration and tube formation in vitro and upregulated the expression of pro-angiogenic factors, including vascular endothelial growth factor (VEGF) and matrix metallopeptidase (MMP)-9 in glioma cells. These SRC-1-mediated effects were dependent on the activation of polyomavirus enhancer activator 3 (PEA3) transcriptional activity. VEGF and VEGF inducer GS4012 induced the direct binding of SRC-1 and PEA3 in glioma cells, and PEA3 could directly bind with VEGF and MMP-9 promoter under GS4012 treatment in glioma cell. The expression of pro-angiogenic factors induced by SRC-1 was abrogated by sh-PEA3 knockdown. Taken together, these novel outcomes indicated that SRC-1 modulated endothelial cell (EC) function and facilitated a pro-angiogenic microenvironment through PEA3 signaling. Moreover, a combination of targeting SRC-1 and PEA3 signaling in glioma could be a promising strategy for suppressing tumor angiogenesis.

scholarly journals ACTIVATION LOOP PHOSPHORYLATION OF A NON-RD RECEPTOR KINASE INITIATES PLANT INNATE IMMUNE SIGNALING

2021 ◽  
Author(s):  
Kyle W Bender ◽  
Daniel Couto ◽  
Yasuhiro Kadota ◽  
Alberto P Macho ◽  
Jan Sklenar ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Conformational Changes ◽  
Stress Responses ◽  
Elongation Factor ◽  
Cytoplasmic Domain ◽  
Dependent Manner ◽  
Immune Signaling ◽  
Receptor Kinases

Receptor kinases (RKs) play fundamental roles in extracellular sensing to regulate development and stress responses across kingdoms. In plants, leucine-rich repeat receptor kinases (LRR-RKs) function primarily as peptide receptors that regulate myriad aspects of plant development and response to external stimuli. Extensive phosphorylation of LRR-RK cytoplasmic domains is among the earliest detectable responses following ligand perception, and reciprocal transphosphorylation between a receptor and its co-receptor is thought to activate the receptor complex. Originally proposed based on characterization of the brassinosteroid receptor, the prevalence of complex activation via reciprocal transphosphorylation across the plant RK family has not been tested. Using the LRR-RK ELONGATION FACTOR TU RECEPTOR (EFR) as a model RK, we set out to understand the steps critical for activating RK complexes. While the EFR cytoplasmic domain is an active protein kinase in vitro and is phosphorylated in a ligand-dependent manner in vivo, catalytically deficient EFR variants are functional in anti-bacterial immunity. These results reveal a non-catalytic role for the EFR cytoplasmic domain in triggering immune signaling and indicate that reciprocal transphoshorylation is not a ubiquitous requirement for LRR-RK complex activation. Rather, our analysis of EFR along with a detailed survey of the literature suggests a distinction between LRR-RK complexes with RD- versus non-RD protein kinase domains. Based on newly identified phosphorylation sites that regulate the activation state of the EFR complex in vivo, we propose that LRR-RK complexes containing a non-RD protein kinase may be regulated by phosphorylation-dependent conformational changes of the ligand-binding receptor which could initiate signaling in a feed-forward fashion either allosterically or through driving the dissociation of negative regulators of the complex.

scholarly journals FKBP12 physically and functionally interacts with aspartokinase in Saccharomyces cerevisiae.

1997 ◽  
Vol 17 (10) ◽  
pp. 5968-5975 ◽  
Author(s):  
C M Alarcón ◽  
J Heitman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Conformational Changes ◽  
Active Site ◽  
Feedback Inhibition ◽  
Immunosuppressive Drugs ◽  
Intermediate Step ◽  
Active Site Residues ◽  
Peptidyl Prolyl Isomerase

The peptidyl-prolyl isomerase FKBP12 was originally identified as the intracellular receptor for the immunosuppressive drugs FK506 (tacrolimus) and rapamycin (sirolimus). Although peptidyl-prolyl isomerases have been implicated in catalyzing protein folding, the cellular functions of FKBP12 in Saccharomyces cerevisiae and other organisms are largely unknown. Using the yeast two-hybrid system, we identified aspartokinase, an enzyme that catalyzes an intermediate step in threonine and methionine biosynthesis, as an in vivo binding target of FKBP12. Aspartokinase also binds FKBP12 in vitro, and drugs that bind the FKBP12 active site, or mutations in FKBP12 surface and active site residues, disrupt the FKBP12-aspartokinase complex in vivo and in vitro.fpr1 mutants lacking FKBP12 are viable, are not threonine or methionine auxotrophs, and express wild-type levels of aspartokinase protein and activity; thus, FKBP12 is not essential for aspartokinase activity. The activity of aspartokinase is regulated by feedback inhibition by product, and genetic analyses reveal that FKBP12 is important for this feedback inhibition, possibly by catalyzing aspartokinase conformational changes in response to product binding.

scholarly journals Reduction of Coactivator Expression by Antisense Oligodeoxynucleotides Inhibits ERα Transcriptional Activity and MCF-7 Proliferation

2002 ◽  
Vol 16 (2) ◽  
pp. 253-270 ◽  
Author(s):  
Ilaria T. R. Cavarretta ◽  
Ratna Mukopadhyay ◽  
David M. Lonard ◽  
Lex M. Cowsert ◽  
C. Frank Bennett ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Activity ◽  
Steroid Receptors ◽  
Biological Effects ◽  
Steroid Receptor ◽  
Transient Transfection ◽  
Antisense Oligodeoxynucleotides ◽  
Steroid Receptor Coactivator ◽  
Mcf 7

Abstract Steroid receptor RNA activator (SRA) is a novel coactivator for steroid receptors that acts as an RNA molecule, whereas steroid receptor coactivator (SRC) family members, such as steroid receptor coactivator-1 (SRC-1) and transcriptional intermediary factor 2 (TIF2) exert their biological effects as proteins. Individual overexpression of each of these coactivators, which can form multimeric complexes in vivo, results in stimulated ERα transcriptional activity in transient transfection assays. However there is no information on the consequences of reducing SRC-1, TIF2, or SRA expression, singly or in combination, on ERα transcriptional activity. We therefore developed antisense oligodeoxynucleotides (asODNs) to SRA, SRC-1, and TIF2 mRNAs, which rapidly and specifically reduced the expression of each of these coactivators. ERα-dependent gene expression was reduced in a dose-dependent fashion by up to 80% in cells transfected with these oligonucleotides. Furthermore, treatment of cells with combinations of SRA, SRC-1, and TIF2 asODNs reduced ERα transcriptional activity to an extent greater than individual asODN treatment alone, suggesting that these coactivators cooperate, in at least an additive fashion, to activate ERα-dependent target gene expression. Finally, treatment of MCF-7 cells with asODN against SRC-1 and TIF2 revealed a requirement of these coactivators, but not SRA, for hormone-dependent DNA synthesis and induction of estrogen-dependent pS2 gene expression, indicating that SRA and SRC family coactivators can fulfill specific functional roles. Taken together, we have developed a rapid method to reduce endogenous coactivator expression that enables an assessment of the in vivo role of specific coactivators on ERα biological action and avoids potential artifacts arising from overexpression of coactivators in transient transfection assays.

scholarly journals Cyclophilin D regulates necrosis, but not apoptosis, of murine eosinophils

2016 ◽  
Vol 310 (8) ◽  
pp. G609-G617 ◽  
Author(s):  
Xiang Zhu ◽  
Simon P. Hogan ◽  
Jeffery D. Molkentin ◽  
Nives Zimmermann
Keyword(s):  
Apoptotic Cell ◽  
Cyclophilin D ◽  
Prolyl Isomerase ◽  
Peptidyl Prolyl Isomerase ◽  
Significant Difference ◽  
Insight Into ◽  
Colitis Model ◽  
Eosinophil Degranulation

Eosinophil degranulation and clusters of free extracellular granules are frequently observed in diverse diseases, including atopic dermatitis, nasal polyposis, and eosinophilic esophagitis. Whether these intact granules are released by necrosis or a biochemically mediated cytolysis remains unknown. Recently, a peptidyl-prolyl isomerase located within the mitochondrial matrix, cyclophilin D (PPIF), was shown to regulate necrotic, but not apoptotic, cell death in vitro in fibroblasts, hepatocytes, and cardiomyocytes. Whether cyclophilin D regulates necrosis in hematopoietic cells such as eosinophils remains unknown. We used PPIF-deficient ( Ppif−/−) mice to test whether cyclophilin D is required for regulating eosinophil necrosis. PPIF deficiency did not affect eosinophil development or maturation at baseline. After in vitro ionomycin or H2O2 treatment, Ppif−/− eosinophils were significantly protected from Ca2+ overload- or oxidative stress-induced necrosis. Additionally, Ppif−/− eosinophils demonstrated significantly decreased necrosis, but not apoptosis, in response to Siglec-F cross-linking, a stimulus associated with eosinophil-mediated processes in vitro and in vivo. When treated with apoptosis inducers, Ppif+/+ and Ppif−/− eosinophils exhibited no significant difference in apoptosis or secondary necrosis. Finally, in a dextran sodium sulfate-induced colitis model, although levels of colitogenic cytokines and eosinophil-selective chemokines were comparable between Ppif+/+ and Ppif−/− mice, the latter exhibited decreased clinical outcomes. This correlated with significantly reduced eosinophil cytolysis in the colon. Collectively, our present studies demonstrate that murine eosinophil necrosis is regulated in vitro and in vivo by cyclophilin D, at least in part, thus providing new insight into the mechanism of eosinophil necrosis and release of free extracellular granules in eosinophil-associated diseases.

scholarly journals The Peptidyl-Prolyl Isomerase Activity of SlyD Is Not Required for Maturation of Escherichia coli Hydrogenase

2007 ◽  
Vol 189 (21) ◽  
pp. 7942-7944 ◽  
Author(s):  
Jie Wei Zhang ◽  
Michael R. Leach ◽  
Deborah B. Zamble
Keyword(s):  
Escherichia Coli ◽  
Metal Cluster ◽  
The Other ◽  
Prolyl Isomerase ◽  
Ppiase Activity ◽  
Peptidyl Prolyl Isomerase ◽  
Isomerase Activity ◽  
Hydrogenase Enzymes

ABSTRACT Escherichia coli SlyD, which is involved in the biosynthesis of the metal cluster in the [NiFe]-hydrogenase enzymes, exhibits several activities including that of a peptidyl-prolyl isomerase (PPIase). Mutations that result in deficient PPIase activity do not produce corresponding decreases in the other activities of SlyD in vitro or in hydrogenase production levels in vivo.

Abstract 378: Macrophage ß3 Integrin is an Important Player in Inflammation and Cellular Plasticity

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Cristina A Wolf ◽  
Izabela Bobak ◽  
Xinming Su ◽  
Ellen Damm ◽  
Katherine N Weilbaecher ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Cellular Response ◽  
Foam Cell ◽  
Foam Cell Formation ◽  
Dependent Manner ◽  
Cellular Plasticity ◽  
Β3 Integrin ◽  
Anti Inflammatory

Communication between cells and the surrounding environment is a crucial mechanism for survival. Integrins are membrane-bound molecules that are involved in signaling between the cells and the extracellular matrix, thereby influencing cytoskeletal stability and intracellular signaling. β3 integrin and its binding partner αv form the αvβ3 heterodimer that is expressed in various cells. We and others have described the consequences of its absence in inflammation, atherosclerosis and cancer in vivo. However, the distinct role of this integrin as a signaling molecule and the consequences of its absence for macrophage structure remain mostly elusive. Our aim is to further characterize the phenotype of β3-deficient (β3-/-) bone marrow-derived macrophages (BMDM) under stimulatory conditions (LPS and LDLs) compared to control cells in vitro. qPCR, WB, ELISA, migration, proliferation assays were used to investigate β3-/- BMDM and controls (wt BMDM and Raw 264.7). LPS was described to be not only pro- but also anti-inflammatory in a time-dependent manner. We show that LPS stimulation leads to high expression of pro-inflammatory cytokines (IL-1β and TNFα) shortly after treatment, while expression of anti-inflammatory cytokine (IL-10) arises at a later stage (12h post stimulation). Interestingly, β3-/- BMDM express more IL-1β than controls. IL-10 expression appears much earlier in β3-/- BMDM (6h post stimulation) but is reduced after 12h, indicating a faster and higher cellular response in the absence of the β3 integrin. OxLDL, the leading cause to foam cell formation, stimulates the expression of IL-1β in controls and β3-/- BMDM with the latter expressing significantly less of this cytokine indicating that lack of β3 causes differential cellular responses after LPS and oxLDL stimulation. Other LDL forms tested (nLDL, acLDL, cLDL) did not have any effect on IL-1β expression. In addition, we identified a higher proliferation rate in the β3-/- BMDM when cultured with M-CSF and a migration deficit in response to LPS, M-CSF and VEGF. Taken together, our results show that macrophage β3 deficiency causes differential cellular plasticity depending on the stimulus, with functional consequences that could be essential in inflammation and atherosclerosis.

The stathmin phosphoprotein family: intracellular localization and effects on the microtubule network

1998 ◽  
Vol 111 (22) ◽  
pp. 3333-3346 ◽  
Author(s):  
O. Gavet ◽  
S. Ozon ◽  
V. Manceau ◽  
S. Lawler ◽  
P. Curmi ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Intracellular Signaling ◽  
Splice Variants ◽  
Intracellular Localization ◽  
Phosphorylation Site ◽  
Dependent Manner ◽  
Microtubule Depolymerization ◽  
Microtubule Network

Stathmin is a small regulatory phosphoprotein integrating diverse intracellular signaling pathways. It is also the generic element of a protein family including the neural proteins SCG10, SCLIP, RB3 and its two splice variants RB3′ and RB3″. Stathmin itself was shown to interact in vitro with tubulin in a phosphorylation-dependent manner, sequestering free tubulin and hence promoting microtubule depolymerization. We investigated the intracellular distribution and tubulin depolymerizing activity in vivo of all known members of the stathmin family. Whereas stathmin is not associated with interphase microtubules in HeLa cells, a fraction of it is concentrated at the mitotic spindle. We generated antisera specific for stathmin phosphoforms, which allowed us to visualize the regulation of phosphorylation-dephosphorylation during the successive stages of mitosis, and the partial localization of stathmin phosphorylated on serine 16 at the mitotic spindle. Results from overexpression experiments of wild-type and novel phosphorylation site mutants of stathmin further suggest that it induces depolymerization of interphase and mitotic microtubules in its unphosphorylated state but is inactivated by phosphorylation in mitosis. Phosphorylation of mutants 16A25A and 38A63A on sites 38 and 63 or 16 and 25, respectively, was sufficient for the formation of a functional spindle, whereas mutant 16A25A38A63E retained a microtubule depolymerizing activity. Transient expression of each of the neural phosphoproteins of the stathmin family showed that they are at least partially associated to the Golgi apparatus and not to other major membrane compartments, probably through their different NH2-terminal domains, as described for SCG10. Most importantly, like stathmin and SCG10, overexpressed SCLIP, RB3 and RB3″ were able to depolymerize interphase microtubules. Altogether, our results demonstrate in vivo the functional conservation of the stathmin domain within each protein of the stathmin family, with a microtubule destabilizing activity most likely essential for their specific biological function(s).

scholarly journals In Vivo Interaction of Steroid Receptor Coactivator (SRC)-1 and the Activation Function-2 Domain of the Thyroid Hormone Receptor (TR) β in TRβ E457A Knock-In and SRC-1 Knockout mice

Endocrinology ◽  
2009 ◽  
Vol 150 (8) ◽  
pp. 3927-3934 ◽  
Author(s):  
Manuela Alonso ◽  
Charles Goodwin ◽  
XiaoHui Liao ◽  
Tania Ortiga-Carvalho ◽  
Danielle S. Machado ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormone Receptor ◽  
Steroid Receptor ◽  
Activation Function ◽  
Steroid Receptor Coactivator ◽  
Pituitary Thyroid Axis ◽  
Serum T4 ◽  
Thyroid Axis

The activation function-2 (AF-2) domain of the thyroid hormone (TH) receptor (TR)-β is a TH-dependent binding site for nuclear coactivators (NCoA), which modulate TH-dependent gene transcription. In contrast, the putative AF-1 domain is a TH-independent region interacting with NCoA. We determined the specificity of the AF-2 domain and NCoA interaction by evaluating thyroid function in mice with combined disruption of the AF-2 domain in TRβ, due to a point mutation (E457A), and deletion of one of the NCoAs, steroid receptor coactivator (SRC)-1. The E457A mutation was chosen because it abolishes NCoA recruitment in vitro while preserving normal TH binding and corepressor interactions resulting in resistance to TH. At baseline, disruption of SRC-1 in the homozygous knock-in (TRβE457A/E457A) mice worsened the degree of resistance to TH, resulting in increased serum T4 and TSH. During TH deprivation, disruption of AF-2 and SRC-1 resulted in a TSH rise 50% of what was seen when AF-2 alone was removed, suggesting that SRC-1 was interacting outside of the AF-2 domain. Therefore, 1) during TH deprivation, SRC-1 is necessary for activating the hypothalamic-pituitary-thyroid axis; 2) ligand-dependent repression of TSH requires an intact AF-2; and 3) SRC-1 may interact with the another region of the TRβ or the TRα to regulate TH action in the pituitary. This report demonstrates the dual interaction of NCoA in vivo: the TH-independent up-regulation possibly through another domain and TH-dependent down-regulation through the AF-2 domain.

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