scholarly journals An allosteric site on MKP5 reveals a strategy for small-molecule inhibition

2020 ◽  
Vol 13 (646) ◽  
pp. eaba3043 ◽  
Author(s):  
Zachary T. K. Gannam ◽  
Kisuk Min ◽  
Shanelle R. Shillingford ◽  
Lei Zhang ◽  
James Herrington ◽  
...  
Keyword(s):  
Small Molecule ◽  
Binding Pocket ◽  
Muscle Disease ◽  
Mitogen Activated Protein Kinase ◽  
Allosteric Site ◽  
Dystrophic Muscle ◽  
Smad2 Phosphorylation ◽  
Mitogen Activated Protein ◽  
P38α Mapk ◽  
Tgf Β1

The mitogen-activated protein kinase (MAPK) phosphatases (MKPs) have been considered “undruggable,” but their position as regulators of the MAPKs makes them promising therapeutic targets. MKP5 has been suggested as a potential target for the treatment of dystrophic muscle disease. Here, we identified an inhibitor of MKP5 using a p38α MAPK–derived, phosphopeptide-based small-molecule screen. We solved the structure of MKP5 in complex with this inhibitor, which revealed a previously undescribed allosteric binding pocket. Binding of the inhibitor to this pocket collapsed the MKP5 active site and was predicted to limit MAPK binding. Treatment with the inhibitor recapitulated the phenotype of MKP5 deficiency, resulting in activation of p38 MAPK and JNK. We demonstrated that MKP5 was required for TGF-β1 signaling in muscle and that the inhibitor blocked TGF-β1–mediated Smad2 phosphorylation. TGF-β1 pathway antagonism has been proposed for the treatment of dystrophic muscle disease. Thus, allosteric inhibition of MKP5 represents a therapeutic strategy against dystrophic muscle disease.

Adaphostin promotes caffeine-evoked autocrine Fas-mediated death pathway activation in Bcr/Abl-positive leukaemia cells

2011 ◽  
Vol 439 (3) ◽  
pp. 453-470 ◽  
Author(s):  
Wen-Hsin Liu ◽  
Long-Sen Chang
Keyword(s):  
P38 Mapk ◽  
K562 Cells ◽  
Mitogen Activated Protein Kinase ◽  
Pathway Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
P38α Mapk ◽  
Activating Transcription Factor ◽  
Leukaemia Therapy ◽  
Jnk Activation

The present study was conducted to verify whether caffeine is beneficial for improving leukaemia therapy. Co-treatment with adaphostin (a Bcr/Abl inhibitor) was found to potentiate caffeine-induced Fas/FasL up-regulation. Although adaphostin did not elicit ASK1 (apoptosis signal-regulating kinase 1)-mediated phosphorylation of p38 MAPK (mitogen-activated protein kinase) and JNK (c-Jun N-terminal kinase), co-treatment with adaphostin notably increased p38 MAPK/JNK activation in caffeine-treated cells. Suppression of p38 MAPK and JNK abrogated Fas/FasL up-regulation in caffeine- and caffeine/adaphostin-treated cells. Compared with caffeine, adaphostin markedly suppressed Akt/ERK (extracellular-signal-regulated kinase)-mediated MKP-1 (MAPK phosphatase 1) protein expression in K562 cells. MKP-1 down-regulation eventually elucidated the enhanced effect of adaphostin on p38 MAPK/JNK activation and subsequent Fas/FasL up-regulation in caffeine-treated cells. Knockdown of p38α MAPK and JNK1, ATF-2 (activating transcription factor 2) and c-Jun by siRNA (small interfering RNA) proved that p38α MAPK/ATF-2 and JNK1/c-Jun pathways were responsible for caffeine-evoked Fas/FasL up-regulation. Moreover, Ca2+ and ROS (reactive oxygen species) were demonstrated to be responsible for ASK1 activation and Akt/ERK inactivation respectively in caffeine- and caffeine/adaphostin-treated cells. Likewise, adaphostin functionally enhanced caffeine-induced Fas/FasL up-regulation in leukaemia cells that expressed Bcr/Abl. Taken together, the results of the present study suggest a therapeutic strategy in improving the efficacy of adaphostin via Fas-mediated death pathway activation in Bcr/Abl-positive leukaemia.

scholarly journals p38 MAPK α and β isoforms differentially regulate plasma membrane localization of MRP2

2016 ◽  
Vol 310 (11) ◽  
pp. G999-G1005 ◽  
Author(s):  
Christopher M. Schonhoff ◽  
Se Won Park ◽  
Cynthia R.L. Webster ◽  
M. Sawkat Anwer
Keyword(s):  
Plasma Membrane ◽  
P38 Mapk ◽  
Hepatoma Cell ◽  
Sodium Taurocholate ◽  
Mitogen Activated Protein Kinase ◽  
Hepatoma Cell Line ◽  
Mitogen Activated Protein ◽  
P38α Mapk ◽  
Opposing Effects ◽  
Interfering Rna

In hepatocytes, cAMP both activates p38 mitogen-activated protein kinase (MAPK) and increases the amount of multidrug resistance-associated protein-2 (MRP2) in the plasma membrane (PM-MRP2). Paradoxically, taurolithocholate (TLC) activates p38 MAPK but decreases PM-MRP2 in hepatocytes. These opposing effects of cAMP and TLC could be mediated via different p38 MAPK isoforms (α and β) that are activated differentially by upstream kinases (MKK3, MKK4, and MKK6). Thus we tested the hypothesis that p38α MAPK and p38β MAPK mediate increases and decreases in PM-MRP2 by cAMP and TLC, respectively. Studies were conducted in hepatocytes isolated from C57BL/6 wild-type (WT) and MKK3-knockout (MKK3−/−) mice and in a hepatoma cell line (HuH7) that overexpresses sodium-taurocholate cotransporting polypeptide (NTCP) (HuH-NTCP). Cyclic AMP activated MKK3, p38 MAPK, and p38α MAPK and increased PM-MRP2 in WT hepatocytes, but failed to activate p38α MAPK or increase PM-MRP2 in MKK3−/− hepatocytes. In contrast to cAMP, TLC activated total p38 MAPK but decreased PM-MRP2, and did not activate MKK3 or p38α MAPK in WT hepatocytes. In MKK3−/− hepatocytes, TLC still decreased PM-MRP2 and activated p38 MAPK, indicating that these effects are not MKK3-dependent. Additionally, TLC activated MKK6 in MKK3−/− hepatocytes, and small interfering RNA knockdown of p38β MAPK abrogated TLC-mediated decreases in PM-MRP2 in HuH-NTCP cells. Taken together, these results suggest that p38α MAPK facilitates plasma membrane insertion of MRP2 by cAMP, whereas p38β MAPK mediates retrieval of PM-MRP2 by TLC.

scholarly journals Inhibiting MAPK14 showed anti-prolactinoma effect

2020 ◽  
Author(s):  
Qiaoyan Ding ◽  
Yu Zhang ◽  
Li Ma ◽  
Yong-gang Chen ◽  
Jin-hu Wu ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Dopamine D2 Receptor ◽  
D2 Receptor ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Gh3 Cells ◽  
Immunofluorescence Analysis ◽  
Mitogen Activated Protein ◽  
P38α Mapk ◽  
Interfering Rna

Abstract Background The specific underlying pathogenesis of prolactinoma has not been clarified yet, to the best of our knowledge. p38 mitogen-activated protein kinase (MAPK) signaling including p38α MAPK (MAPK14), p38β (MAPK11), p38γ (MAPK12) and p38δ (MAPK13) is associated with the development and progression of several types of cancer.Methods Immunofluorescence analysis was performed on the prolactin (PRL) and MAPK14 expressions of pituitary gland in C57BL/6 mice and human prolactinoma specimen. In the present study, the role of MAPK14 in prolactinoma was determined using estradiol-induced mice and dopamine D2 receptor knockout (DRD2-/-) mice models in C57BL/6 wild-type (WT), MAPK14-/- and DRD2-/-MAPK14+/- mice. GH3 cells were transfected with different sets of MAPK14 small interfering RNA, which to study MAPK14 and PRL expression in GH3 cells.Results Immunofluorescence analysis showed that PRL and MAPK14 expression were colocalized and increased in the pituitary gland of mice and human prolactinoma specimen compared with the control specimen. It was shown that PRL and MAPK14 expression was colocalized and increased significantly in the pituitary gland of estradiol-injected prolactinoma mice compared with the control mice. Knockout of MAPK14 significantly inhibited tumor overgrowth, and PRL expression was decreased in estradiol-induced mice. Furthermore, MAPK14 knockout of DRD2-/-MAPK14+/- mice significantly reduced the overgrowth of pituitary gland and PRL production and secretion compared with DRD2-/- mice. MAPK14 knockout using siRNA inhibited PRL production in GH3 cells.Conclusion These results suggest that MAPK14 serves a promoting role in the formation of prolactinoma, and highlights the potential of MAPK14 as a potential therapeutic target in the treatment of prolactinoma.

Abstract 1172: Neointima Formation is Dependent on p38α Mitogen-Activated Protein Kinase

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Brandon M Proctor ◽  
Anthony J Muslin
Keyword(s):  
P38 Mapk ◽  
Carotid Arteries ◽  
Thymidine Incorporation ◽  
Fold Increase ◽  
Arterial Injury ◽  
Mitogen Activated Protein Kinase ◽  
Neointima Formation ◽  
Mapk Activity ◽  
Mitogen Activated Protein ◽  
P38α Mapk

Neointima formation frequently occurs after arterial injury and is responsible for substantial human morbidity. We previously demonstrated that the intracellular linker protein Grb2 is required for neointima formation, and that Grb2 regulates p38α mitogen-activated protein kinase (MAPK) activation in vascular smooth muscle cells (SMCs). In this work, the role of p38α MAPK in neointima formation was examined. In vitro experiments showed that pharmacological inhibition of p38 MAPK activity in cultured SMCs blocked platelet-derived growth factor (PDGF)-stimulated DNA replication and cell proliferation. Specifically, in control SMCs, overnight stimulation with PDGF induced an 11.8-fold increase in thymidine incorporation and a 1.9 fold increase in cell number. However, inhibition of p38 MAPK activity reduced PDGF-induced thymidine incorporation to 2.8-fold (P = 0.0006) and completely blocked PDGF-stimulated cell proliferation (P = 0.0001). Also, p38 MAPK activity was required for PDGF-induced inactivation of the retinoblastoma tumor suppressor protein, Rb, and induction of mini-chromosome maintenance protein-6 (MCM6), a fundamental regulator of DNA replication. Next, compound transgenic mice were generated with doxycycline (Dox)-inducible, SMC-specific expression of a dominant-negative form of p38α MAPK (SMC-DN-p38α ). Dox induced robust expression of DN-p38α mRNA and protein in the aorta and carotid arteries of compound transgenic mice, and inactivation of native, arterial p38 MAPK. SMC-DN-p38α and single transgenic, control mice were subjected to carotid injury by use of an epoxy resin-beaded probe. After 21 days, control mice developed robust neointima formation that frequently resulted in an occlusive lesion with a mean neointima/media ratio of 2.62 (N = 8). In contrast, SMC-DN-p38α mice were resistant to the development of neointima. Specifically, neointima/media ratio was reduced to 0.63 for SMC-DN-p38α mice (N = 12; P = 0.045). In addition, compared to control mice, injured carotid arteries of SMC-DN-p38α mice showed defective p38 MAPK activation in SMCs of the tunica media. Our results demonstrate that vascular SMC p38α MAPK is required for neointima formation after arterial injury.

scholarly journals p38 MAPK inhibits autophagy and promotes microglial inflammatory responses by phosphorylating ULK1

2017 ◽  
Vol 217 (1) ◽  
pp. 315-328 ◽  
Author(s):  
Yingli He ◽  
Hua She ◽  
Ting Zhang ◽  
Haidong Xu ◽  
Lihong Cheng ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Inflammatory Responses ◽  
Morphological Changes ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Activity ◽  
Dependent Inhibition ◽  
Mitogen Activated Protein ◽  
P38α Mapk ◽  
Mechanistic Basis

Inflammation and autophagy are two critical cellular processes. The relationship between these two processes is complex and includes the suppression of inflammation by autophagy. However, the signaling mechanisms that relieve this autophagy-mediated inhibition of inflammation to permit a beneficial inflammatory response remain unknown. We find that LPS triggers p38α mitogen-activated protein kinase (MAPK)–dependent phosphorylation of ULK1 in microglial cells. This phosphorylation inhibited ULK1 kinase activity, preventing it from binding to the downstream effector ATG13, and reduced autophagy in microglia. Consistently, p38α MAPK activity is required for LPS-induced morphological changes and the production of IL-1β by primary microglia in vitro and in the brain, which correlates with the p38α MAPK-dependent inhibition of autophagy. Furthermore, inhibition of ULK1 alone was sufficient to promote an inflammatory response in the absence of any overt inflammatory stimulation. Thus, our study reveals a molecular mechanism that enables the initial TLR4-triggered signaling pathway to inhibit autophagy and optimize inflammatory responses, providing new understanding into the mechanistic basis of the neuroinflammatory process.

Role of platelet-derived growth factor-B, vascular endothelial growth factor, insulin-like growth factor-II, mitogen-activated protein kinase and transforming growth factor-β1 in expansion-induced lung growth in fetal sheep

2006 ◽  
Vol 18 (6) ◽  
pp. 655 ◽  
Author(s):  
Megan J. Wallace ◽  
Alison M. Thiel ◽  
Andrea M. Lines ◽  
Graeme R. Polglase ◽  
Foula Sozo ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Mapk Pathway ◽  
Fetal Lung ◽  
Mitogen Activated Protein Kinase ◽  
Insulin Like Growth Factor ◽  
Lung Expansion ◽  
Mitogen Activated Protein ◽  
Extracellular Matrix Remodelling ◽  
Tgf Β1

Increased fetal lung expansion induces lung growth, cell differentiation and extracellular matrix remodelling, although the mechanisms involved are unknown. Platelet-derived growth factor (PDGF)-B, vascular endothelial growth factor (VEGF) and insulin-like growth factor (IGF)-II are mitogens activating the mitogen-activated protein kinase (MAPK) pathway, whereas transforming growth factor (TGF)-β1 induces differentiation and extracellular matrix remodelling. In the present study, we investigated the mRNA levels of PDGF-B, VEGF, IGF-II and TGF-β1, as well as active MAPK levels, during increased fetal lung expansion induced by tracheal obstruction (TO) in sheep for 0 (controls), 36 h or 2, 4, or 10 days (n = 5 in each group). The 3.7-kb VEGF transcript increased by 30% (P < 0.05) at 36 h TO. The expression of PDGF-B decreased by approximately 25% (P < 0.01) at 2–10 days TO. In contrast, TGF-β1 mRNA increased by 96% (P < 0.05) at 10 days TO, when bioactive TGF-β1 decreased by 55% (P < 0.05). Insulin-like growth factor-II mRNA tended to increase at 10 days TO (37% above controls; P = 0.07), whereas mRNA for its receptor, IGF1R, was reduced by TO. There was no change in active MAPK levels preceding or at the time of a TO-induced 800% increase in cell proliferation. We conclude that VEGF is likely to promote expansion-induced endothelial cell proliferation, but the mechanisms underlying expansion-induced proliferation of fibroblasts and alveolar epithelial cells are unlikely to be mediated by increases in PDGF-B or IGF-II expression or activation of the MAPK pathway.

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