scholarly journals Ablation of MEKK4 Kinase Activity Causes Neurulation and Skeletal Patterning Defects in the Mouse Embryo

2005 ◽  
Vol 25 (20) ◽  
pp. 8948-8959 ◽  
Author(s):  
Amy N. Abell ◽  
Jaime A. Rivera-Perez ◽  
Bruce D. Cuevas ◽  
Mark T. Uhlik ◽  
Susan Sather ◽  
...  
Keyword(s):  
Heat Shock ◽  
Protein Kinase ◽  
Neural Tube ◽  
Small Heat Shock Protein ◽  
Neural Tube Closure ◽  
Mitogen Activated Protein Kinase ◽  
Skeletal Patterning ◽  
Targeted Mutation ◽  
Mitogen Activated Protein ◽  
P38 Pathway

ABSTRACT Skeletal disorders and neural tube closure defects represent clinically significant human malformations. The signaling networks regulating normal skeletal patterning and neurulation are largely unknown. Targeted mutation of the active site lysine of MEK kinase 4 (MEKK4) produces a kinase-inactive MEKK4 protein (MEKK4K1361R). Embryos homozygous for this mutation die at birth as a result of skeletal malformations and neural tube defects. Hindbrains of exencephalic MEKK4K1361R embryos show a striking increase in neuroepithelial cell apoptosis and a dramatic loss of phosphorylation of MKK3 and -6, mitogen-activated protein kinase kinases (MKKs) regulated by MEKK4 in the p38 pathway. Phosphorylation of MAPK-activated protein kinase 2, a p38 substrate, is also inhibited, demonstrating a loss of p38 activity in MEKK4K1361R embryos. In contrast, the MEK1/2-extracellular signal-regulated kinase 1 (ERK1)/ERK2 and MKK4-Jun N-terminal protein kinase pathways were unaffected. The p38 pathway has been shown to regulate the phosphorylation and expression of the small heat shock protein HSP27. Compared to the wild type, MEKK4K1361R fibroblasts showed significantly reduced phosphorylation of p38 and HSP27, with a corresponding heat shock-induced instability of the actin cytoskeleton. Together, these data demonstrate MEKK4 regulation of p38 and that substrates downstream of p38 control cellular homeostasis. The findings are the first demonstration that MEKK4-regulated p38 activity is critical for neurulation.

scholarly journals The Molecular Chaperone Heat Shock Protein 70 Controls Liver Cancer Initiation and Progression by Regulating Adaptive DNA Damage and Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Signaling Pathways

2019 ◽  
Vol 39 (9) ◽  
Author(s):  
Wonkyoung Cho ◽  
Xiongjie Jin ◽  
Junfeng Pang ◽  
Yan Wang ◽  
Nahid F. Mivechi ◽  
...  
Keyword(s):  
Dna Damage ◽  
Heat Shock ◽  
Protein Kinase ◽  
Heat Shock Protein ◽  
Heat Shock Protein 70 ◽  
Cell Transformation ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT Delineating the mechanisms that drive hepatic injury and hepatocellular carcinoma (HCC) progression is critical for development of novel treatments for recurrent and advanced HCC but also for the development of diagnostic and preventive strategies. Heat shock protein 70 (HSP70) acts in concert with several cochaperones and nucleotide exchange factors and plays an essential role in protein quality control that increases survival by protecting cells against environmental stressors. Specifically, the HSP70-mediated response has been implicated in the pathogenesis of cancer, but the specific mechanisms by which HSP70 may support malignant cell transformation remains to be fully elucidated. Here, we show that genetic ablation of HSP70 markedly impairs HCC initiation and progression by distinct but overlapping pathways. This includes the potentiation of the carcinogen-induced DNA damage response, at the tumor initiation stage, to increase the p53-dependent surveillance response leading to the cell cycle exit or death of genomically damaged differentiated pericentral hepatocytes, and this may also prevent their conversion into more proliferating HCC progenitor cells. Subsequently, activation of a mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) negative feedback pathway diminishes oncogenic signals, thereby attenuating premalignant cell transformation and tumor progression. Modulation of HSP70 function may be a strategy for interfering with oncogenic signals driving liver cell transformation and tumor progression, thus providing an opportunity for human cancer control.

Mitogen-Activated Protein Kinase p38 Pathway in Venous Ulcer Fibroblasts

2008 ◽  
Vol 42 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Joseph D. Raffetto ◽  
Christopher H. Gram ◽  
Kristen C. Overman ◽  
James O. Menzoian
Keyword(s):  
Protein Kinase ◽  
Venous Ulcer ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
P38 Pathway

scholarly journals Heat-shock protein-25/27 phosphorylation by the δ isoform of protein kinase C

1998 ◽  
Vol 332 (3) ◽  
pp. 703-712 ◽  
Author(s):  
Evelyn T. MAIZELS ◽  
Carl A. PETERS ◽  
Michael KLINE ◽  
Richard E. CUTLER ◽  
Malathy SHANMUGAM ◽  
...  
Keyword(s):  
Heat Shock ◽  
Protein Kinase ◽  
Late Pregnancy ◽  
Mitogen Activated Protein Kinase ◽  
Corpora Lutea ◽  
Hsp 27 ◽  
Pkc Isoforms ◽  
Mitogen Activated Protein

Small heat-shock proteins (sHSPs) are widely expressed 25–28 kDa proteins whose functions are dynamically regulated by phosphorylation. While recent efforts have clearly delineated a stress-responsive p38 mitogen-activated protein-kinase (MAPK)-dependent kinase pathway culminating in activation of the heat-shock (HSP)-kinases, mitogen-activated protein-kinase-activated protein kinase-2 and -3, not all sHSP phosphorylation events can be explained by the p38 MAPK-dependent pathway. The contribution of protein kinase C (PKC) to sHSP phosphorylation was suggested by early studies but later questioned on the basis of the reported poor ability of purified PKC to phosphorylate sHSP in vitro. The current study re-evaluates the role of PKC in sHSP phosphorylation in the light of the isoform complexity of the PKC family. We evaluated the sHSP phosphorylation status in rat corpora lutea obtained from two stages of pregnancy, mid-pregnancy and late-pregnancy, which express different levels of the novel PKC isoform, PKC-δ. Two-dimensional Western blot analysis showed that HSP-27 was more highly phosphorylated in vivo in corpora lutea of late pregnancy, corresponding to the developmental stage in which PKC-δ is abundant and active. Late-pregnant luteal extracts contained a lipid-sensitive HSP-kinase activity which exactly co-purified with PKC-δ using hydroxyapatite and S-Sepharose column chromatography. To determine whether there might be preferential phosphorylation of sHSP by a particular PKC isoform, purified recombinant PKC isoforms corresponding to those PKC isoforms detected in rat corpora lutea were evaluated for HSP-kinase activity in vitro. Recombinant PKC-δ effectively catalysed the phosphorylation of sHSP in vitro, and PKC-α was 30–50% as effective as an HSP-kinase; other PKCs tested (β1, β2, ε and ζ) were poor HSP-kinases. These results show that select PKC family members can function as direct HSP-kinases in vitro. Moreover, the observation of enhanced luteal HSP-27 phosphorylation in vivo, in late pregnancy, when PKC-δ is abundant and active, suggests that select PKC family members contribute to sHSP phosphorylation events in vivo.

31 EFFECT OF TREATMENT OF OVINE CYTOPLASTS WITH CAFFEINE ON THE TRANSLOCALIZATION OF HSP27 IN SOMATIC CELL NUCLEAR TRANSFER RECONSTRUCTED EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 134
Author(s):  
I. Choi ◽  
J.-H. Lee ◽  
K. H. S. Campbell
Keyword(s):  
Gene Expression ◽  
Heat Shock ◽  
Protein Kinase ◽  
Somatic Cell Nuclear Transfer ◽  
Nuclear Transfer ◽  
Blastocyst Stage ◽  
Total Cell ◽  
Mitogen Activated Protein Kinase ◽  
Hsp 27 ◽  
Mitogen Activated Protein

We have previously reported that treatment of enucleated ovine oocytes with 10 mM caffeine for 6 h increases the activities of maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK) (Lee and Campbell 2006 Biol. Reprod. 74, 691–698). In addition, when used as cytoplast recipients for somatic cell nuclear transfer (SCNT), the resultant blastocyst stage embryos show an increase in total cell numbers. Furthermore, we have also found that gene expression profiles observed following caffeine treatment more closely resemble those of IVF embryos than non-treated SCNT embryos. In particular, heat shock protein 27 (HSP-27, a molecular chaperon was down-regulated in non-treated SCNT embryos. In contrast, in caffeine-treated SNCT embryos, levels of transcripts were similar to those of IVF embryos (Choi et al. 2006 Reprod. Fertil. Dev. 18, 122). Several studies on heat shock protein 25 (HSP-25)/HSP-27 demonstrated that HSP-27 was underexpressed in SCNT bovine embryos (Pfister-Genskow et al. 2005 Biol. Reprod. 72, 546–555), and phosphorylated HSP-25 becomes sub-localized in nucleus following heat shock condition in mouse embryos (Kim et al. 2002 Mol. Reprod. Dev. 61, 3–13). In cultured cells, HSP-25 phosphorylation was mediated by mitogen-activated protein kinase (MAPK), suggesting that nuclear-translocated HSP-25 might function to protect nuclear structure, thereby preventing apoptosis (Geum et al. 2002 J. Biol. Chem. 277, 19 913–19 921). In this study, we investigated the effects of caffeine treatment on the localization of HSP-27 by fluorescene immunocytochemistry in SCNT and control embryos. HSP-27 was detected primarily in the cytoplasm of non-treated SCNT embryos from the 1-cell stage onwards; however, some nulear staining was observed in some embryos. In contrast, in caffeine-treated SCNT embryos, a more intense immunostaining of HSP-27 was observed in the nucleus than in the cytoplasm. This result indicated that HSP-27 was phosphorylated and translocated into nucleus in SCNT embryos treated with caffeine. In addition, we also examined the levels of transcripts of upstream genes of HSP-27 such as p38MAPKs, and MAPK-activated protein kinase 5 (Mapkapk5) by semi-quantitative RT-PCR. The levels of Mapkapk5 and p38MAPKs transcriptional expression were constant among groups. These observations suggest that the effects mediated by caffeine on HSP-27 occur before the onset of zygotic transcription, are independent of gene expression, but are maintained until the blastocyst stage. Taken together, our results suggest that the down-regulated expression of HSP-27 in SCNT embryos may be linked with the increased incidence of programmed cell death. In contrast, the elevated expression of HSP-27 and increased nuclear translocation observed in caffeine-treated SCNT embryos may contribute to the increase in total cell number we have previously reported at the blastocyst stage.

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