scholarly journals Stage-specific Requirement of a Mitogen-activated Protein Kinase by Trypanosoma brucei

2002 ◽  
Vol 13 (11) ◽  
pp. 3787-3799 ◽  
Author(s):  
Ingrid B. Müller ◽  
Debora Domenicali-Pfister ◽  
Isabel Roditi ◽  
Erik Vassella
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Phosphorylation Site ◽  
Tsetse Fly ◽  
Mitogen Activated Protein Kinase ◽  
Mammalian Host ◽  
Null Mutant ◽  
African Trypanosomes ◽  
Mitogen Activated Protein

In cycling between the mammalian host and the tsetse fly vector, African trypanosomes undergo adaptive differentiation steps that are coupled to growth control. The signaling pathways underlying these cellular processes are largely unknown. Mitogen-activated protein kinases (MAPKs) are known mediators of growth and differentiation in other eukaryotic organisms. To establish the function of a MAPK homologue, TbMAPK2, in T. brucei, a null mutant was constructed. Bloodstream forms of aΔmapk2/Δmapk2 clone were able to grow normally and exhibited no detectable phenotype. When these cells were triggered to differentiate in vitro, however, they developed to the procyclic (fly midgut) form with delayed kinetics and subsequently underwent cell cycle arrest. Introduction of an ectopic copy of theTbMAPK2 gene into the null mutant restored its ability to differentiate and to divide. In contrast, a TbMAPK2mutant, in which the T190 and Y192 residues of the activating phosphorylation site were replaced by A and F, was unable to restore the growth and differentiation phenotypes. Analysis of the DNA content and the nucleus/kinetoplast configuration of individual cells showed that the null mutant was arrested in all phases of the cell cycle and that 25–30% of the cells had failed to segregate their nucleus and kinetoplast correctly. This implies that cell cycle progression by the procyclic form depends on a constitutive stimulus exerted by the signaling cascade operating through TbMAPK2.

Sperm penetration of immature and maturing oocytes does not affect phosphorylation of mitogen-activated protein kinase in pigs

2003 ◽  
Vol 15 (7) ◽  
pp. 383 ◽  
Author(s):  
H. M. Quan ◽  
X. Q. Meng ◽  
Y. Hou ◽  
Q. Y. Sun
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Cell Cycle Progression ◽  
Germinal Vesicle ◽  
Mitogen Activated Protein Kinase ◽  
Cycle Progression ◽  
Mapk Phosphorylation ◽  
Mitogen Activated Protein ◽  
Sperm Penetration

Pig oocytes cultured in vitro for 0, 25, 33 and 44 h were inseminated by frozen–thawed ejaculated sperm. At specified times after insemination, sperm penetration, cell cycle progression and mitogen-activated protein kinase (MAPK) phosphorylation were evaluated. It was shown that: (1) oocytes at various maturational stages could be penetrated by sperm; (2) sperm penetration did not affect meiotic cell cycle progression; (3) sperm penetration of germinal vesicle (GV) oocytes and maturing oocytes did not alter MAPK phosphorylation; and (4) when premetaphase I (pre-MI) and metaphase I (MI) oocytes, in which MAPK was activated, were fertilised, no evident MAPK dephosphorylation was detected as in metaphase II oocytes. The data suggest that sperm penetration before oocyte maturation does not affect MAPK phosphorylation and that the machinery inactivating MAPK upon fertilisation is not developed in maturing (pre-MI to MI) oocytes.

scholarly journals A Mitogen-Activated Protein Kinase Controls Differentiation of Bloodstream Forms of Trypanosoma brucei

2006 ◽  
Vol 5 (7) ◽  
pp. 1126-1135 ◽  
Author(s):  
Debora Domenicali Pfister ◽  
Gabriela Burkard ◽  
Sabine Morand ◽  
Christina Kunz Renggli ◽  
Isabel Roditi ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Tsetse Fly ◽  
Mitogen Activated Protein Kinase ◽  
Regulatory Function ◽  
Mammalian Host ◽  
Mutant Form ◽  
Wild Type ◽  
African Trypanosomes ◽  
Life Cycle Stages ◽  
Mitogen Activated Protein

ABSTRACT African trypanosomes undergo differentiation in order to adapt to the mammalian host and the tsetse fly vector. To characterize the role of a mitogen-activated protein (MAP) kinase homologue, TbMAPK5, in the differentiation of Trypanosoma brucei, we constructed a knockout in procyclic (insect) forms from a differentiation-competent (pleomorphic) stock. Two independent knockout clones proliferated normally in culture and were not essential for other life cycle stages in the fly. They were also able to infect immunosuppressed mice, but the peak parasitemia was 16-fold lower than that of the wild type. Differentiation of the proliferating long slender to the nonproliferating short stumpy bloodstream form is triggered by an autocrine factor, stumpy induction factor (SIF). The knockout differentiated prematurely in mice and in culture, suggestive of increased sensitivity to SIF. In contrast, a null mutant of a cell line refractory to SIF was able to proliferate normally. The differentiation phenotype was partially rescued by complementation with wild-type TbMAPK5 but exacerbated by introduction of a nonactivatable mutant form. Our results indicate a regulatory function for TbMAPK5 in the differentiation of bloodstream forms of T. brucei that might be exploitable as a target for chemotherapy against human sleeping sickness.

scholarly journals Evidence for an interplay between cell cycle progression and the initiation of differentiation between life cycle forms of African trypanosomes.

1994 ◽  
Vol 125 (5) ◽  
pp. 1147-1156 ◽  
Author(s):  
K R Matthews ◽  
K Gull
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Blood Stream ◽  
Tsetse Fly ◽  
Mammalian Host ◽  
Cycle Progression ◽  
African Trypanosomes ◽  
Host Blood ◽  
Proliferative Cell ◽  
Differentiation Model

Successful transmission of the African trypanosome between the mammalian host blood-stream and the tsetse fly vector involves dramatic alterations in the parasite's morphology and biochemistry. This differentiation through to the tsetse midgut procyclic form is accompanied by re-entry into a proliferative cell cycle. Using a synchronous differentiation model and a variety of markers diagnostic for progress through both differentiation and the cell cycle, we have investigated the interplay between these two processes. Our results implicate a relationship between the trypanosome cell cycle position and the perception of the differentiation signal and demonstrate that irreversible commitment to the differentiation occurs rapidly after induction. Furthermore, we show that re-entry into the cell cycle in the differentiating population is synchronous, and that once initiated, progress through the differentiation pathway can be uncoupled from progress through the cell cycle.

Parkinson´s related protein DJ-1 is involved in aberrant cell cycle re-entry through Cdk5

2020 ◽  
Author(s):  
Mª José López-Grueso ◽  
Carmen Alicia Padilla ◽  
José Antonio Bárcena ◽  
Raquel Requejo-Aguilar
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Cortical Neurons ◽  
Cell Cycle Progression ◽  
Cell Cycle Checkpoints ◽  
Mitogen Activated Protein Kinase ◽  
Signalling Pathways ◽  
Multifunctional Protein ◽  
Mitogen Activated Protein ◽  
Phosphoinositide 3 Kinase

Abstract DJ-1 is a multifunctional protein involved in Parkinson disease (PD) that can act as antioxidant, molecular chaperone, protease, glyoxalase and transcriptional regulator. However, the exact mechanism by which DJ-1 dysfunction contributes to development of Parkinson´s disease remains elusive. Here, using a comparative proteomic analysis between normal cortical neurons and neurons lacking DJ-1, we show that this protein is involved in cell cycle checkpoints disruption as a consequence of increased amount of p-Tau and a-synuclein proteins, altered signalling pathways, as the phosphoinositide-3-kinase/protein kinase B (PI3K/AKT) and mitogen-activated protein kinase (MAPK), and deregulation of cyclin-dependent kinase 5 (Cdk5). Cdk5 is normally involved in dendritic growth, axon formation and the establishment of synapses, but can also contribute to cell cycle progression, as in our case, in pathological conditions. In addition, we observed a decrease in proteasomal activity, probably due to Tau phosphorylation that can also lead to activation of mitogenic signalling pathways. Taken together, our findings indicate, for the first time, that aborted cell cycle re-entry could be at the onset of DJ-1 associated PD. Thereby, new approaches targeting cell cycle re-entry can be envisaged to improve current therapeutic strategies.

scholarly journals The major phosphorylation site of the NADPH oxidase component p67phox is Thr233

1999 ◽  
Vol 338 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Louisa V. FORBES ◽  
Oanh TRUONG ◽  
Frans B. WIENTJES ◽  
Stephen J. MOSS ◽  
Anthony W. SEGAL
Keyword(s):  
Protein Kinase ◽  
Cyanogen Bromide ◽  
Tryptic Peptide ◽  
Phosphorylation Site ◽  
Mitogen Activated Protein Kinase ◽  
Rich Domain ◽  
Mitogen Activated Protein ◽  
Phosphopeptide Mapping ◽  
Major Phosphorylation Site

Phosphorylation of p67phox was shown to increase two- to three-fold upon stimulation by PMA, N-formylmethionyl-leucylphenylalanine or serum-opsonized zymosan. Phosphopeptide mapping showed one major tryptic peptide for p67phox immunoprecipitated from resting or stimulated cells. In vitro phosphorylation of p67phox by isolated cytosol or mitogen-activated protein kinase also generated the same phosphopeptide. Results of cyanogen bromide digestion and HPLC–MS suggested that Thr233 was the phosphorylated residue. Mutagenesis of Thr233 to alanine resulted in loss of phosphorylation in vitro. In the present work, Thr233 has been identified as the major phosphorylation site of p67phox, which is situated in a proline-rich domain.

Phosphorylation of Argonaute 2 at serine-387 facilitates its localization to processing bodies

2008 ◽  
Vol 413 (3) ◽  
pp. 429-436 ◽  
Author(s):  
Yan Zeng ◽  
Heidi Sankala ◽  
Xiaoxiao Zhang ◽  
Paul R. Graves
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Kinase Inhibitor ◽  
Mapk Pathway ◽  
Phosphorylation Site ◽  
Mitogen Activated Protein Kinase ◽  
Processing Bodies ◽  
Mitogen Activated Protein

Ago (Argonaute) proteins are essential effectors of RNA-mediated gene silencing. To explore potential regulatory mechanisms for Ago proteins, we examined the phosphorylation of human Ago2. We identified serine-387 as the major Ago2 phosphorylation site in vivo. Phosphorylation of Ago2 at serine-387 was significantly induced by treatment with sodium arsenite or anisomycin, and arsenite-induced phosphorylation was inhibited by a p38 MAPK (mitogen-activated protein kinase) inhibitor, but not by inhibitors of JNK (c-Jun N-terminal kinase) or MEK [MAPK/ERK (extracellular-signal-regulated kinase) kinase]. MAPKAPK2 (MAPK-activated protein kinase-2) phosphorylated bacterially expressed full-length human Ago2 at serine-387 in vitro, but not the S387A mutant. Finally, mutation of serine-387 to an alanine residue or treatment of cells with a p38 MAPK inhibitor reduced the localization of Ago2 to processing bodies. These results suggest a potential regulatory mechanism for RNA silencing acting through Ago2 serine-387 phosphorylation mediated by the p38 MAPK pathway.

scholarly journals Regulation of cyclin D1 expression and cell cycle progression by mitogen-activated protein kinase cascade

1999 ◽  
Vol 56 (4) ◽  
pp. 1258-1261 ◽  
Author(s):  
Yoshio Terada ◽  
Seiji Inoshita ◽  
Osamu Nakashima ◽  
Michio Kuwahara ◽  
Sei Sasaki ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Cyclin D1 ◽  
Cell Cycle Progression ◽  
Mitogen Activated Protein Kinase ◽  
Cycle Progression ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Protein Kinase Cascade

scholarly journals Mitogen-activated protein kinase-mediated phosphorylation of peroxiredoxin 6 regulates its phospholipase A2 activity

2009 ◽  
Vol 419 (3) ◽  
pp. 669-679 ◽  
Author(s):  
Yongzheng Wu ◽  
Sheldon I. Feinstein ◽  
Yefim Manevich ◽  
Ibrul Chowdhury ◽  
Jhang Ho Pak ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Phospholipase A2 ◽  
Kinase Inhibitors ◽  
Phosphorylation Site ◽  
Protein Kinase Inhibitors ◽  
Mitogen Activated Protein Kinase ◽  
Alveolar Type ◽  
Peroxiredoxin 6 ◽  
Mitogen Activated Protein

Prdx6 (peroxiredoxin 6), a bifunctional protein with both GSH peroxidase and PLA2 (phospholipase A2) [aiPLA2 (acidic calcium-independent PLA2)] activities, is responsible for the metabolism of lung surfactant phospholipids. We propose that the aiPLA2 activity of the enzyme is regulated through phosphorylation. Incubation of isolated rat alveolar type II cells (AECII) with PMA, a PKC (protein kinase C) agonist, had no effect on Prdx6 expression but led to ∼75% increase in aiPLA2 activity that was abolished by pretreatment of cells with the MAPK (mitogen-activated protein kinase) inhibitors, SB202190 or PD98059. Prdx6 phosphorylation after incubation of AECII with PMA was demonstrated by autoradiography after immunoprecipitation with either anti-phosphothreonine o-phosphoserine antibodies. in vitro, several active isoforms of ERK (extracellular-signal-regulated kinase) and p38 phosphorylated Prdx6, resulting in an 11-fold increase in aiPLA2 activity. The increased activity was calcium-independent and was abolished by the aiPLA2 inhibitors, surfactant protein A and hexadecyl-3-trifluorethylglycero-sn-2-phospho-methanol (MJ33). The peroxidase activity of Prdx6 was unaffected by phosphorylation. Mass spectroscopic analysis of in vitro phosphorylated Prdx6 showed a unique phosphorylation site at Thr-177 and mutation of this residue abolished protein phosphorylation and the increase in MAPK-mediated activity. These results show that the MAPKs can mediate phosphorylation of Prdx6 at Thr-177 with a consequent marked increase in its aiPLA2 activity.

scholarly journals Cell Cycle Arrest and Reversion of Ras-Induced Transformation by a Conditionally Activated Form of Mitogen-Activated Protein Kinase Kinase Kinase 3

1999 ◽  
Vol 19 (5) ◽  
pp. 3857-3868 ◽  
Author(s):  
Heidrun Ellinger-Ziegelbauer ◽  
Kathleen Kelly ◽  
Ulrich Siebenlist
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Cyclin D1 ◽  
Stress Responses ◽  
Cell Cycle Progression ◽  
Cellular Transformation ◽  
Mitogen Activated Protein Kinase ◽  
Cycle Progression ◽  
Mapk Kinase ◽  
Mitogen Activated Protein

ABSTRACT Signal-induced proliferation, differentiation, or stress responses of cells depend on mitogen-activated protein kinase (MAPK) cascades, the core modules of which consist of members of three successively acting kinase families (MAPK kinase kinase [MAP3K], MAPK kinase, and MAPK). It is demonstrated here that the MEKK3 kinase inhibits cell proliferation, a biologic response not commonly associated with members of the MAP3K family of kinases. A conditionally activated form of MEKK3 stably expressed in fibroblasts arrests these cells in early G1. MEKK3 critically blocks mitogen-driven expression of cyclin D1, a cyclin which is essential for progression of fibroblasts through G1. The MEKK3-induced block of cyclin D1 expression and of cell cycle progression may be mediated via p38 MAPK, a downstream effector of MEKK3. The MEKK3-mediated block of proliferation also reverses Ras-induced cellular transformation, suggesting possible tumor-suppressing functions for this kinase. Together, these results suggest an involvement of the MEKK3 kinase in negative regulation of cell cycle progression, and they provide the first insights into biologic activities of this kinase.

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