Role of individual phosphorylation sites for the 14-3-3-protein-dependent activation of yeast neutral trehalase Nth1

2012 ◽  
Vol 443 (3) ◽  
pp. 663-670 ◽  
Author(s):  
Dana Veisova ◽  
Eva Macakova ◽  
Lenka Rezabkova ◽  
Miroslav Sulc ◽  
Petr Vacha ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Limited Proteolysis ◽  
Terminal Segment ◽  
Protein Isoforms ◽  
Stable Complex ◽  
Phosphorylation Sites ◽  
Dependent Manner ◽  
Neutral Trehalase ◽  
Activity Measurements

Trehalases are important highly conserved enzymes found in a wide variety of organisms and are responsible for the hydrolysis of trehalose that serves as a carbon and energy source as well as a universal stress protectant. Emerging evidence indicates that the enzymatic activity of the neutral trehalase Nth1 in yeast is enhanced by 14-3-3 protein binding in a phosphorylation-dependent manner through an unknown mechanism. In the present study, we investigated in detail the interaction between Saccharomyces cerevisiae Nth1 and 14-3-3 protein isoforms Bmh1 and Bmh2. We determined four residues that are phosphorylated by PKA (protein kinase A) in vitro within the disordered N-terminal segment of Nth1. Sedimentation analysis and enzyme kinetics measurements show that both yeast 14-3-3 isoforms form a stable complex with phosphorylated Nth1 and significantly enhance its enzymatic activity. The 14-3-3-dependent activation of Nth1 is significantly more potent compared with Ca2+-dependent activation. Limited proteolysis confirmed that the 14-3-3 proteins interact with the N-terminal segment of Nth1 where all phosphorylation sites are located. Site-directed mutagenesis in conjunction with the enzyme activity measurements in vitro and the activation studies of mutant forms in vivo suggest that Ser60 and Ser83 are sites primarily responsible for PKA-dependent and 14-3-3-mediated activation of Nth1.

POSSIBLE ROLE FOR THE CA2+-DEPENDENT PROTEASE (CALPAIN I) AS AN IRREVERSIBLE ACTIVATOR OF CA2+/CALMODULIN-MEDIATED REACTIONS IN THE HUMAN PLATELET

1987 ◽  
Author(s):  
Robert W Wallace ◽  
E Ann Tallant ◽  
Lynn M Brumley
Keyword(s):  
Myosin Light Chain ◽  
Binding Proteins ◽  
Human Platelet ◽  
Limited Proteolysis ◽  
Physiological Role ◽  
Human Platelets ◽  
Dependent Manner ◽  
Protease Activation ◽  
Stimulation Of

Calmodulin (CaM)-binding proteins have been identified in human platelets using Western blotting techniques and 125I-CaM. Ten proteins of 245, 225. 175, 150, 90. 82(2), 60 and 41(2) kilodaltons (kDa) bind 125I-CaM in a Ca2+-dependent manner; the binding is blocked by both trifluoperazine and nonradiolabeled CaM. The 225 and 90 kDa proteins are labeled by antisera against myosin light chain kinase (MLCK); the 60 kDa and one of the 82 kDa proteins have been identified as the CaM-dependent phosphatase (calcineurin) and caldesmon. The other proteins are presumed to be other Ca2+/CaM regulated enzymes and proteins which may be important in platelet function. Most of the CaM-binding proteins are degraded upon addition of Ca2+ to a platelet homogenate; the degradation may be blocked by either EGTA, leupeptin or N-ethylmaleimide which suggests that the degradation is due to a Ca2+-dependent protease. Activation of intact platelets under conditions which promote platelet aggregation (i.e. stirring with extracellular Ca2+) also results in limited proteolysis of CaM-binding proteins including those labeled with anti sera against MLCK and the phosphatase. In vitro studies utilizing purified phosphatase and calpain I indicate that the phosphatase is irreversibly activated upon Ca2+-dependent proteolysis. The proteolytically-activated enzyme is insensitive to either Ca2+ or Ca2+/CaM; in addition, its activity in the absence of Ca2+ is even greater than the activity of the unproteolyzed enzyme in the presence of Ca2+ and CaM. Proteolytic stimulation of the phosphatase is accompanied by degradation of the 60 kDa subunit of the enzyme (subunit A) to 56, 52 and 45 kDa fragments, sequentially; proteolysis results in the loss of CaM binding to the enzyme. These results suggest that the Ca2+-dependent protease may have a physiological role in platelet activation as an irreversible activator of Ca2+/ CaM-dependent reactions. Supported by NIH grant HL29766.

scholarly journals Brain-targeted enzyme-loaded nanoparticles: A breach through the blood-brain barrier for enzyme replacement therapy in Krabbe disease

2019 ◽  
Vol 5 (11) ◽  
pp. eaax7462 ◽  
Author(s):  
Ambra Del Grosso ◽  
Marianna Galliani ◽  
Lucia Angella ◽  
Melissa Santi ◽  
Ilaria Tonazzini ◽  
...  
Keyword(s):  
Nervous System ◽  
Enzymatic Activity ◽  
Krabbe Disease ◽  
Brain Targeting ◽  
Cell Trafficking ◽  
Lysosomal Storage ◽  
Cns Involvement ◽  
Enzyme Replacement ◽  
Activity Measurements

Lysosomal storage disorders (LSDs) result from an enzyme deficiency within lysosomes. The systemic administration of the missing enzyme, however, is not effective in the case of LSDs with central nervous system (CNS)-involvement. Here, an enzyme delivery system based on the encapsulation of cross-linked enzyme aggregates (CLEAs) into poly-(lactide-co-glycolide) (PLGA) nanoparticles (NPs) functionalized with brain targeting peptides (Ang2, g7 or Tf2) is demonstrated for Krabbe disease, a neurodegenerative LSD caused by galactosylceramidase (GALC) deficiency. We first synthesize and characterize Ang2-, g7- and Tf2-targeted GALC CLEA NPs. We study NP cell trafficking and capability to reinstate enzymatic activity in vitro. Then, we successfully test our formulations in the Twitcher mouse. We report enzymatic activity measurements in the nervous system and in accumulation districts upon intraperitoneal injections, demonstrating activity recovery in the brain up to the unaffected mice level. Together, these results open new therapeutic perspectives for all LSDs with major CNS-involvement.

Proteolytic Modulation of Thrombopoietin Activity: Comparison of Thrombin, Plasmin, and Urokinase

2000 ◽  
Vol 83 (06) ◽  
pp. 909-914 ◽  
Author(s):  
Kaelen Aramaki ◽  
Alexander Reiner
Keyword(s):  
Marked Decrease ◽  
Limited Proteolysis ◽  
Full Length ◽  
Time Dependent ◽  
Dependent Manner ◽  
Terminal Fragment ◽  
Activity Comparison

SummarySeveral observations suggest that limited proteolysis of full-length 70 kD human thrombopoietin (Tpo) may be important for Tpo biology. Recently, it was reported that thrombin cleaves full-length recombinant human Tpo (rhTpo) sequentially at two sites, Arg195 within the glycan domain followed by Arg117 within the cytokine domain, and that these cleavages modulate Tpo activity in vitro. We demonstrate that urokinase and plasmin also cleave rhTpo in a time-dependent manner. Urokinase cleavage is confined to the glycan domain, and generates a 35 kD N-terminal fragment that contains the intact cytokine domain, and is associated with increased Tpo activity. In contrast, plasmin cleaves Tpo sequentially at two specific sites (Arg205 within the glycan domain followed by Lys52 within the cytokine domain), and is associated with a marked decrease in Tpo activity. These proteolytic events have potential implications for regulation of Tpo activity in vivo.

C-terminal domain phosphorylation of ERK3 controlled by Cdk1 and Cdc14 regulates its stability in mitosis

2010 ◽  
Vol 428 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Pierre-Luc Tanguay ◽  
Geneviève Rodier ◽  
Sylvain Meloche
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Mitotic Cell ◽  
Mitogen Activated Protein Kinase ◽  
Phosphorylation Sites ◽  
Dependent Manner ◽  
Cell Extracts ◽  
Cycle Dependent

ERK3 (extracellular-signal-regulated kinase 3) is an atypical MAPK (mitogen-activated protein kinase) that is suggested to play a role in cell-cycle progression and cellular differentiation. However, it is not known whether the function of ERK3 is regulated during the cell cycle. In the present paper, we report that ERK3 is stoichiometrically hyperphosphorylated during entry into mitosis and is dephosphorylated at the M→G1 transition. The phosphorylation of ERK3 is associated with the accumulation of the protein in mitosis. In vitro phosphorylation of a series of ERK3-deletion mutants by mitotic cell extracts revealed that phosphorylation is confined to the unique C-terminal extension of the protein. Using MS analysis, we identified four novel phosphorylation sites, Ser684, Ser688, Thr698 and Ser705, located at the extreme C-terminus of ERK3. All four sites are followed by a proline residue. We have shown that purified cyclin B-Cdk1 (cyclindependent kinase 1) phosphorylates these sites in vitro and demonstrate that Cdk1 acts as a major Thr698 kinase in vivo. Reciprocally, we found that the phosphatases Cdc14A and Cdc14B (Cdc is cell-division cycle) bind to ERK3 and reverse its C-terminal phosphorylation in mitosis. Importantly, alanine substitution of the four C-terminal phosphorylation sites markedly decreased the half-life of ERK3 in mitosis, thereby linking phosphorylation to the stabilization of the kinase. The results of the present study identify a novel regulatory mechanism of ERK3 that operates in a cell-cycle-dependent manner.

scholarly journals Effects of Ozone Oxidative Preconditioning on TNF-αRelease and Antioxidant-Prooxidant Intracellular Balance in Mice During Endotoxic Shock

2005 ◽  
Vol 2005 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Zullyt B. Zamora ◽  
Aluet Borrego ◽  
Orlay Y. López ◽  
René Delgado ◽  
Ricardo González ◽  
...  
Keyword(s):  
Glutathione Peroxidase ◽  
Enzymatic Activity ◽  
Redox State ◽  
Endotoxic Shock ◽  
Gaseous Mixture ◽  
Hepatic Tissue ◽  
Mouse Serum ◽  
Antioxidant Systems ◽  
Dependent Manner

Ozone oxidative preconditioning is a prophylactic approach, which favors the antioxidant-prooxidant balance for preservation of cell redox state by the increase of antioxidant endogenous systems in both in vivo and in vitro experimental models. Our aim is to analyze the effect of ozone oxidative preconditioning on serum TNF-αlevels and as a modulator of oxidative stress on hepatic tissue in entodoxic shock model (mice treated with lipopolysaccharide (LPS)). Ozone/oxygen gaseous mixture which was administered intraperitoneally (0.2,0.4, and1.2mg/kg) once daily for five days before LPS (0.1mg/kg, intraperitoneal). TNF-αwas measured by cytotoxicity on L-929 cells. Biochemical parameters such as thiobarbituric acid reactive substances (TBARS), enzymatic activity of catalase, glutathione peroxidase, and glutathione-S transferase were measured in hepatic tissue. One hour after LPS injection there was a significant increase in TNF-αlevels in mouse serum. Ozone/oxygen gaseous mixture reduced serum TNF-αlevels in a dose-dependent manner. Statistically significant decreases in TNF-αlevels after LPS injection were observed in mice pretreated with ozone intraperitoneal applications at0.2(78%),0.4(98%), and1.2(99%). Also a significant increase in TBARS content was observed in the hepatic tissue of LPS-treated mice, whereas enzymatic activity of glutathion-S transferase and glutathione peroxidase was decreased. However in ozone-treated animals a significant decrease in TBARS content was appreciated as well as an increase in the activity of antioxidant enzymes. These results indicate that ozone oxidative preconditioning exerts inhibitory effects on TNF-αproduction and on the other hand it exerts influence on the antioxidant-prooxidant balance for preservation of cell redox state by the increase of endogenous antioxidant systems.

scholarly journals Thymoquinone Inhibits Growth of Acute Myeloid Leukemia Cells through Reversal SHP-1 and SOCS-3 Hypermethylation: In Vitro and In Silico Evaluation

2021 ◽  
Vol 14 (12) ◽  
pp. 1287
Author(s):  
Futoon Abedrabbu Al-Rawashde ◽  
Muhammad Farid Johan ◽  
Wan Rohani Wan Taib ◽  
Imilia Ismail ◽  
Syed Ahmad Tajudin Tuan Johari ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Acute Myeloid Leukemia ◽  
Enzymatic Activity ◽  
Myeloid Leukemia ◽  
Nigella Sativa ◽  
Dependent Manner ◽  
Cancer Pathogenesis ◽  
Stat Signaling ◽  
Acute Myeloid

Epigenetic silencing of tumor suppressor genes (TSGs) plays an essential role in cancer pathogenesis, including acute myeloid leukemia (AML). All of SHP-1, SOCS-1, and SOCS-3 are TSGs that negatively regulate JAK/STAT signaling. Enhanced re-expression of TSGs through de-methylation represents a therapeutic target in several cancers. Thymoquinone (TQ) is a major component of Nigella sativa seeds with anticancer effects against several cancers. However, the effects of TQ on DNA methylation are not entirely understood. This study aimed to evaluate the ability of TQ to re-express SHP-1, SOCS-1, and SOCS-3 in MV4-11 AML cells through de-methylation. Cytotoxicity, apoptosis, and cell cycle assays were performed using WSTs-8 kit, Annexin V-FITC/PI apoptosis detection kit, and fluorometric-red cell cycle assay kit, respectively. The methylation of SHP-1, SOCS-1, and SOCS-3 was evaluated by pyrosequencing analysis. The expression of SHP-1, SOCS-1, SOCS-3, JAK2, STAT3, STAT5A, STAT5B, FLT3-ITD, DNMT1, DNMT3A, DNMT3B, TET2, and WT1 was assessed by RT-qPCR. The molecular docking of TQ to JAK2, STAT 3, and STAT5 was evaluated. The results revealed that TQ significantly inhibited the growth of MV4-11 cells and induced apoptosis in a dose- and time-dependent manner. Interestingly, the results showed that TQ binds the active pocket of JAK2, STAT3, and STAT5 to inhibit their enzymatic activity and significantly enhances the re-expression of SHP-1 and SOCS-3 through de-methylation. In conclusion, TQ curbs MV4-11 cells by inhibiting the enzymatic activity of JAK/STAT signaling through hypomethylation and re-expression of JAK/STAT negative regulators and could be a promising therapeutic candidate for AML patients.

scholarly journals A Minimal Chimera of Human Cyclin T1 and Tat Binds TAR and Activates Human Immunodeficiency Virus Transcription in Murine Cells

2002 ◽  
Vol 76 (24) ◽  
pp. 12934-12939 ◽  
Author(s):  
Koh Fujinaga ◽  
Dan Irwin ◽  
Ran Taube ◽  
Fan Zhang ◽  
Matthias Geyer ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Dimensional Structure ◽  
Stable Complex ◽  
Transcriptional Elongation ◽  
Dependent Manner ◽  
Cyclin T1 ◽  
Immunodeficiency Virus ◽  
Tar Rna ◽  
Hiv 1

ABSTRACT The transcriptional elongation of human immunodeficiency virus type 1 (HIV-1) is mediated by the virally encoded transactivator Tat and its cellular cofactor, positive transcription elongation factor b (P-TEFb). The human cyclin T1 (hCycT1) subunit of P-TEFb forms a stable complex with Tat and the transactivation response element (TAR) RNA located at the 5′ end of all viral transcripts. Previous studies have demonstrated that hCycT1 binds Tat in a Zn2+-dependent manner via the cysteine at position 261, which is a tyrosine in murine cyclin T1. In the present study, we mutated all other cysteines and histidines that could be involved in this Zn2+-dependent interaction. Because all of these mutant proteins except hCycT1(C261Y) activated viral transcription in murine cells, no other cysteine or histidine in hCycT1 is responsible for this interaction. Next, we fused the N-terminal 280 residues in hCycT1 with Tat. Not only the full-length chimera but also the mutant hCycT1 with an N-terminal deletion to position 249, which retained the Tat-TAR recognition motif, activated HIV-1 transcription in murine cells. This minimal hybrid mutant hCycT1-Tat protein bound TAR RNA as well as human and murine P-TEFb in vitro. We conclude that this minimal chimera not only reproduces the high-affinity binding among P-TEFb, Tat, and TAR but also will be invaluable for determining the three-dimensional structure of this RNA-protein complex.

scholarly journals Estradiol Up-regulates AUF1p45 Binding to Stabilizing Regions within the 3′-Untranslated Region of Estrogen Receptor α mRNA

2007 ◽  
Vol 283 (3) ◽  
pp. 1764-1772 ◽  
Author(s):  
Nancy H. Ing ◽  
Dana A. Massuto ◽  
Laurie A. Jaeger
Keyword(s):  
Estrogen Receptor ◽  
Untranslated Region ◽  
Binding Proteins ◽  
Rna Binding ◽  
Regulation Of Gene Expression ◽  
Estrogen Receptor Α ◽  
Protein Isoforms ◽  
Dependent Manner ◽  
Estradiol Treatment

Estradiol up-regulates expression of the estrogen receptor α gene in the uterus by stabilizing estrogen receptor α mRNA. Previously, we defined two discrete minimal estradiol-modulated stability sequences (MEMSS) within the extensive 3′-untranslated region of estrogen receptor α mRNA with an in vitro stability assay using cytosolic extracts from sheep uterus. We report here that excess MEMSS RNA inhibited the enhanced stability of estrogen receptor α mRNA in extracts from estradiol-treated ewes compared with those from control ewes. Several estradiol-induced MEMSS-binding proteins were characterized by UV cross-linking in uterine extracts from ewes in a time course study (0, 8, 16, and 24 h after estradiol injection). The pattern of binding proteins changed at 16 h post-injection, concurrent with enhanced estrogen receptor α mRNA stability and the highest rate of accumulation of estrogen receptor α mRNA. The predominant MEMSS-binding protein induced by estradiol treatment was identified as AUF1 (A + U-rich RNA-binding factor 1) protein isoform p45 (a product of the heterogeneous nuclear ribonucleoprotein D gene). Immunoblot analysis indicated that only two of four AUF1 protein isoforms were present in the uterine cytosolic extracts and that estradiol treatment strongly increased the ratio of AUF1 isoforms p45 to p37. Nonphosphorylated recombinant AUF1p45 protected estrogen receptor α mRNA in vitro in a dose-dependent manner. These studies describe estrogenic induction of AUF1p45 binding to the estrogen receptor α mRNA as a molecular mechanism for post-transcriptional up-regulation of gene expression.

Release of Type II phospholipase A2 immunoreactivity and phospholipase A2 enzymatic activity from human placenta

1997 ◽  
Vol 153 (1) ◽  
pp. 151-157 ◽  
Author(s):  
W Farrugia ◽  
G E Rice ◽  
M H Wong ◽  
K F Scott ◽  
S P Brennecke
Keyword(s):  
Enzyme Activity ◽  
Enzymatic Activity ◽  
Phospholipase A2 ◽  
Incubation Medium ◽  
Placental Tissue ◽  
Dependent Manner ◽  
Type Ii ◽  
Intracellular Enzyme ◽  
Human Placental Tissue

Abstract The aim of this study was to determine whether Type II phospholipase A2 (PLA2) is released from late pregnant human placental tissue. Placental explants were incubated in vitro and the release of immunoreactive (ir) Type II PLA2 and PLA2 enzymatic activity into the medium was determined. Both irType II PLA2 and PLA2 enzymatic activity accumulated in the incubation medium in a time-dependent manner (P<0·0001). This release was not associated with a loss of cell membrane integrity, as indicated by measurement of the intracellular enzyme, lactate dehydrogenase, in the incubation medium. The concentration of irType II PLA2 and PLA2 enzyme activity present in incubation medium were significantly correlated (P<0·01). Consistent with the hypothesis that Type II PLA2 may be stored in secretory granules within human placental tissue, incubation in the presence of a membrane depolarising concentration of KCl (60 mm) caused the release of irType II PLA2 2·0-fold (P<0·001). PLA2 enzyme activity released into the incubation medium displays biochemical characteristics consistent with those previously reported for secretory PLA2 isozymes, that is, a requirement for millimolar concentrations of calcium for optimal enzyme activity, inhibited by reducing agents, such as dithiothreitol and insensitive to heat inactivation. The data obtained in this study establish that irType II PLA2 is released from term placenta, when incubated in vitro. The release of this extracellularly-active PLA2 isozyme may contribute to gestational and labour-associated increases in glycerophospholipid metabolism and prostaglandin formation. Journal of Endocrinology (1997) 153, 151–157

scholarly journals Delineating Molecular Mechanisms of Squamous Tissue Homeostasis and Neoplasia: Focus on p63

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Kathryn E. King ◽  
Linan Ha ◽  
Tura Camilli ◽  
Wendy C. Weinberg
Keyword(s):  
Squamous Cell ◽  
Molecular Mechanisms ◽  
Protein Isoforms ◽  
Cancer Development ◽  
Regulatory Function ◽  
Dependent Manner ◽  
Downstream Effector ◽  
Multiple Protein ◽  
Squamous Tissue

Mouse models have informed us that p63 is critical for normal epidermal development and homeostasis. The p53/p63/p73 family is expressed as multiple protein isoforms due to a combination of alternative promoter usage and C-terminal alternative splicing. These isoforms can mimic or interfere with one another, and their balance ultimately determines biological outcome in a context-dependent manner. While not frequently mutated, p63, and in particular the ΔNp63 subclass, is commonly overexpressed in human squamous cell cancers.In vitrokeratinocytes and murine transgenic and transplantation models have been invaluable in elucidating the contribution of altered p63 levels to cancer development, and studies have identified the roles for ΔNp63 isoforms in keratinocyte survival and malignant progression, likely due in part to their transcriptional regulatory function. These findings can be extended to human cancers; for example, the novel recognition of NFκB/c-Rel as a downstream effector of p63 has identified a role for NFκB/c-Rel in human squamous cell cancers. These models will be critical in enhancing the understanding of the specific molecular mechanisms of cancer development and progression.

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