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Reversible phosphorylation by kinase and phosphatase. Phosphorylation is an essential post-translational modification that is mediated by kinases. Reversible phosphorylation induces conformational change within the protein or provides a platform for phospho-binding proteins, which in turn triggers alterations in protein stability, activity, interaction, or subcellular localization. Because phosphorylation regulates diverse protein functions, it should be tightly controlled by the reverse reaction-dephosphorylation catalyzed by phosphatases. X represents a protein that is reversibly phosphorylated and dephosphorylated, and p stands for a phosphate. ATP, adenosine triphosphate; ADP, adenosine diphosphate.
Source publication
Protein phosphorylation affects conformational change, interaction, catalytic activity, and subcellular localization of proteins. Because the post-modification of proteins regulates diverse cellular signaling pathways, the precise control of phosphorylation states is essential for maintaining cellular homeostasis. Kinases function as phosphorylatin...
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Cigarette smoking has been considered as an independent risk factor for colorectal cancer (CRC) initiation and progression. In this study, we found that cigarette smoking was significantly associated with poor CRC differentiation (P = 0.040). Since studies have indicated that poorly differentiated tumors are more aggressive and metastasize earlier,...
Citations
... Existing research indicates the indispensability of JNK activation in governing apoptosis in various malignancies, including gastric cancer [35][36][37]. JNK/p38 MAPK pathway activation occurs through a cascade involving MAP3Ks and MAP2Ks, encompassing ASK1-3, TAK1, MEKK1-4, MLK1-3, DLKs, MKK4, and MKK7 [38]. Our work demonstrated that RGS16 binds to TAB2 and inhibits TAB2-TRAF6 interaction thus exerted a suppressive effect on TAK1-JNK/p38-mediated apoptosis. ...
Colorectal cancer (CRC) remains a major global cause of cancer-related mortality, lacking effective biomarkers and therapeutic targets. Revealing the critical pathogenic factors of CRC and the underlying mechanisms would offer potential therapeutic strategies for clinical application. G protein signaling (RGS) protein family modulators play essential role within regulating downstream signaling of GPCR receptors, with function in cancers unclear. Our study focused on the expression patterns of RGS proteins in CRC, identifying Regulator of G protein signaling 16 (RGS16) as a prospective diagnostic and therapeutic target. Analyzing 899 CRC tissues revealed elevated RGS16 levels, correlating with clinicopathological features and CRC prognosis by immunohistochemistry (IHC) combined with microarray. We confirmed the elevated RGS16 protein level in CRC, and found that patients with RGS16-high tumors exhibited decreased disease-specific survival (DSS) and disease-free survival (DFS) compared to those with low RGS16 expression. Functional assays demonstrated that RGS16 promoted the CRC progression, knockdown of RGS16 led to significantly increased apoptosis rates of CRC in vitro and in vivo. Notably, we also confirmed these phenotypes of RGS16 in organoids originated from resected primary human CRC tissues. Mechanistically, RGS16 restrained JNK/P38-mediated apoptosis in CRC cells through disrupting the recruitment of TAB2/TAK1 to TRAF6. This study provides insights into addressing the challenges posed by CRC, offering avenues for clinical translation.
... Dual specificity phosphatases (DUSPs) dephosphorylate both threonine/serine and tyrosine residues in their substrates. Members of a subfamily of DUSPs contain the MAP kinase-binding motif or the kinase-interacting motif, which is involved in regulating the magnitude and duration of signal transduction via the MAPK/JNK pathway through the dephosphorylation of their substrates [19,20]. Especially, DUSP8, DUSP10, and DUSP16 preferentially inactivate JNK [20]. ...
Purpose
c-Jun N-terminal kinases (JNKs) comprise a subfamily of mitogen-activated protein kinases (MAPKs). The JNK group is known to be activated by a variety of stimuli. However, the molecular mechanism underlying heat-induced JNK activation is largely unknown. The aim of this study was to clarify how JNK activity is stimulated by heat.
Methods and materials
The expression levels of various MAPK members in HeLa cells, with or without hyperthermia treatment, were evaluated via western blotting. The kinase activity of MAPK members was assessed through in vitro kinase assays. Cell death was assessed in the absence or presence of siRNAs targeting MAPK-related members.
Results
Hyperthermia decreased the levels of MAP3Ks, such as ASK1 and MLK3 which are JNK kinase kinase members, but not those of the downstream MAP2K/SEK1 and MAPK/JNK. Despite the reduced or transient phosphorylation of ASK1, MLK3, or SEK1, downstream JNK was phosphorylated in a temperature-dependent manner. In vitro kinase assays demonstrated that heat did not directly stimulate SEK1 or JNK. However, the expression levels of DUSP16, a JNK phosphatase, were decreased upon hyperthermia treatment. DUSP16 knockdown enhanced the heat-induced activation of ASK1–SEK1–JNK pathway and apoptosis.
Conclusion
JNK was activated in a temperature-dependent manner despite reduced or transient phosphorylation of the upstream MAP3K and MAP2K. Hyperthermia-induced degradation of DUSP16 may induce activation of the ASK1–SEK1–JNK pathway and subsequent apoptosis.
... The phosphorylation and activity of JNK are subject to regulation by multiple upstream kinases and phosphatases [14,17,18]. Notably, Dual-Specificity Phosphatases (DUSPs) play a significant role in this regulation. ...
... JNKs, activated by dual phosphorylation at threonine and tyrosine within the TPY motif, undergo dephosphorylation by DUSPs. This dephosphorylation negatively regulates JNK activity and its downstream targets, including c-Jun [17]. ...
Cancer cells employ adaptive mechanisms to survive various stressors, including genotoxic drugs. Understanding the factors promoting survival is crucial for developing effective treatments. In this study, we unveil a previously unexplored long non-coding RNA, JUNI (JUN-DT, LINC01135), which is upregulated by genotoxic drugs through the activation of stress-activated MAPKs, JNK, and p38 and consequently exerts positive control over the expression of its adjacent gene product c-Jun, a well-known oncoprotein, which transduces signals to multiple transcriptional outputs. JUNI regulates cellular migration and has a crucial role in conferring cellular resistance to chemotherapeutic drugs or UV radiation. Depletion of JUNI markedly increases the sensitivity of cultured cells and spheroids to chemotherapeutic agents. We identified 57 proteins interacting with JUNI. The activity of one of them the MAPK phosphatase and inhibitor, DUSP14, is counteracted by JUNI, thereby, facilitating efficient JNK phosphorylation and c-Jun induction when cells are exposed to UV radiation. The antagonistic interplay with DUSP14 contributes not only to c-Jun induction but also augments the survival of UV-exposed cells. In summary, we introduce JUNI as a novel stress-inducible regulator of c-Jun, positioning it as a potential target for enhancing the sensitivity of cancer cells to chemotherapy.
... Our results showed that overexpression of DUSP8 increased protein levels in the cytoplasmic fractions of A549 and H1299 cells, but did not alter the phosphorylation of JNK upstream MAPK signaling molecules. In addition, overexpression of DUSP8 significantly reduced the ability of colony formation, proliferation and migration in two different cell lines but did not significantly affect apoptosis, indicating an interference with nuclear translocation of JNK and further activation of transcription factor targets [24]. Consistent with our results, Ding et al. reported that overexpression of DUSP8 significantly suppressed the proliferation and migration of colon cancer cells in vitro [11]. ...
Dual-specificity phosphatase 8 (DUSP8) plays an important role as a selective c-Jun N-terminal kinase (JNK) phosphatase in mitogen-activated protein kinase (MAPK) signaling. In this study, we found that DUSP8 is silenced by miR-147b in patients with lung adenocarcinoma (LUAD), which correlates with poor overall survival. Overexpression of DUSP8 resulted in a tumor-suppressive phenotype in vitro and in vivo experimental models, whereas silencing DUSP8 with a siRNA approach abrogated the tumor-suppressive properties. We found that miR-147b is a posttranscriptional regulator of DUSP8 that is highly expressed in patients with LUAD and is associated with lower survival. NanoString analysis revealed that the MAPK signaling pathway is mainly affected by overexpression of miR-147b, leading to increased proliferation and migration and decreased apoptosis in vitro. Moreover, induction of miR-147b promotes tumor progression in vitro and in vivo experimental models. Knockdown of miR-147b restored DUSP8, decreased tumor progression in vitro, and increased apoptosis via JNK phosphorylation. These results suggest that miR-147b plays a key role in regulating MAPK signaling in LUAD. The link between DUSP8 and miR-147b may provide novel approaches for the treatment of lung cancer.
... Mitogen-activated protein kinase phosphatase 1 (MKP1, gene name Dusp1), the archetypal member of the dual-specificity phosphatases, has been identified as a negative regulator of both JNK and p38 MAPK through dephosphorylation (18)(19)(20). Previous investigations have suggested that an ethanol-mediated increase in oxidative stress and proteasomal degradation of MKP1 protein leads to JNK-mediated apoptosis of hepatocytes after acute exposure to ethanol (21). ...
Background
It is well established that females are more susceptible to the toxic effects of alcohol, although the exact mechanisms are still poorly understood. Previous studies noted that alcohol reduces the expression of mitogen-activated protein kinase phosphatase 1 (MKP1), a negative regulator of mitogen-activated protein kinases (MAPK) in the liver. However, the role of hepatocyte- specific MKP1 in the pathogenesis of alcohol-associated liver disease (ALD) remains uncharacterized. This study aimed to evaluate the role of hepatocyte-specific MKP1 in the susceptibility and sexual dimorphism in alcohol-induced liver injury.
Methods
C57Bl/6 mice were used in an intragastric ethanol feeding model of alcohol-associated steatohepatitis (ASH). Hepatocyte-specific Mkp1-/- knockout and (Mkp1+/+ “f/f” male and female mice were subjected to the NIAAA chronic plus binge model. Primary mouse hepatocytes were used for in vitro studies. Liver RNA sequencing was performed on an Illumina NextSeq 500. Liver injury was evaluated by plasma alanine transaminase (ALT), hepatic ER stress and inflammation markers. Statistical analysis was carried out using ANOVA and the unpaired Student’s t-test.
Results
ASH was associated with the severe injury accompanied by increased endoplasmic reticulum (ER) stress and significant downregulation of Dusp1 mRNA expression. In vitro, ethanol treatment resulted in a time-dependent decrease in Dusp1 mRNA and protein expression in primary hepatocytes in both males and females; however, this effect was significantly more pronounced in hepatocytes from females. In vivo, female mice developed more liver injury in a chronic plus binge model which was accompanied by a significant decrease in liver Dusp1 mRNA expression. In comparison, liver Dusp1 was not changed in male mice, while they developed milder injury to alcohol. Mkp1 deletion in hepatocytes led to increased alcohol induced liver injury, ER stress and inflammation in both sexes.
Conclusion
Hepatocyte Mkp1 plays a significant role in alcohol induced liver injury. Alcohol downregulates Mkp1 expression in hepatocytes in a sex dependent manner and could play a role in sexual dimorphism in increased female susceptibility to alcohol.
... The role of the JNK (c-Jun N-terminal protein kinase) signaling pathway downstream of MAPK has been thoroughly understood in the pathogenesis of DM. In response to stress stimuli such as environmental factors and inflammation, the JNK proteins are stimulated by a cascade of phosphorylation reactions (49,50). Oxidative stress activates TNF receptor-associated factors (Traf-4 and Traf-6) and the consequent stimulation of JNK signaling in different tissues. ...
Objective(s)
This study focused on the evaluation of antioxidant and antidiabetic activities of polyherbal extract (PHE), containing Cassia absus (L.), Gymnema sylvestre (R. Br.), Nigella sativa (L.), and Piper nigrum (L.), in alloxan-induced diabetes model.
Materials and Methods
In vitro, HPLC characterization, DPPH scavenging assay, and α-amylase inhibition test were conducted. In vivo, acute oral toxicity of PHE was assessed. Alloxan-induced diabetic Wistar rats (n=6) were orally treated with PHE (200, 400, and 600 mg/kg/day) and glibenclamide (GLB; 10 mg/kg/day) for six consecutive weeks. Then, biochemical biomarkers, oxidative stress parameters, histopathological examination, and mRNA expression levels (RT-qPCR) were determined.
Results
The presence of polyphenols in PHE was confirmed in correlation to marked DPPH scavenging (IC50: 1.60 mg/ml) and α-amylase inhibition (IC50: 0.82 mg/ml). PHE demonstrated no toxicity in rats up to a dose of 2000 mg/kg. In diabetic rats, PHE dose-dependently ameliorated the serum levels of glucose, insulin, glycated hemoglobin A1c (HbA1c), leptin, and glucokinase (GCK). Also, PHE substantially alleviated serum inflammatory markers (TNF-α and CRP) and oxidative stress indicators (MDA, SOD, and CAT) in pancreatic tissues. PHE, particularly at 600 mg/kg, attenuated cellular oxidative stress via modulating the mRNA expression levels of genes regulating MAPK/JNK (Mapk-8, Traf-4, and Traf-6) and Nrf-2/Keap-1 pathways and promoted insulin signaling through up-regulating insulin signaling cascade (Pdx-1, Ins-1, and Ins-2), as compared to GLB. Furthermore, histopathological findings supported the aforementioned results.
Conclusion
Our study suggests that polyherbal extract has promising antioxidant and antidiabetic activities by modulating the MAPK/JNK, Nrf-2/Keap-1, and insulin signaling pathways.
... Dual-specificity phosphatases (DUSPs) regulate the magnitude and duration of signaling in MAPK pathways and are regulated at the gene expression level. 29 Thus, we assessed the effects of Tet2 deficiency on expression of the 17 DUSPs that have been associated with altered JNK activation. 29 Although several DUSPs showed moderately reduced expression, only Dusp10 mRNA expression was markedly decreased by TET2 deficiency in both murine Tet2 −/− BMDMs and isogenic human TET2 −/− embryonic stem cell (hESC)-derived macrophages compared with WT controls (Figure 2A and 2B). ...
... 29 Thus, we assessed the effects of Tet2 deficiency on expression of the 17 DUSPs that have been associated with altered JNK activation. 29 Although several DUSPs showed moderately reduced expression, only Dusp10 mRNA expression was markedly decreased by TET2 deficiency in both murine Tet2 −/− BMDMs and isogenic human TET2 −/− embryonic stem cell (hESC)-derived macrophages compared with WT controls (Figure 2A and 2B). Dusp10 expression was decreased in Tet2 +/− BMDMs ( Figure S2A) and in Ly6G − CD11b + splenic monocytes/ macrophages from WTD-fed Tet2 CH Ldlr −/− mice compared with WTD fed Ldlr −/− controls ( Figure 2C). ...
BACKGROUND
Clonal hematopoiesis (CH) has emerged as an independent risk factor for atherosclerotic cardiovascular disease, with activation of macrophage inflammasomes as a potential underlying mechanism. The NLRP3 (NLR family pyrin domain containing 3) inflammasome has a key role in promoting atherosclerosis in mouse models of Tet2 CH, whereas inhibition of the inflammasome product interleukin-1β appeared to particularly benefit patients with TET2 CH in CANTOS (Cardiovascular Risk Reduction Study [Reduction in Recurrent Major CV Disease Events]). TET2 is an epigenetic modifier that decreases promoter methylation. However, the mechanisms underlying macrophage NLRP3 inflammasome activation in TET2 (Tet methylcytosine dioxygenase 2) deficiency and potential links with epigenetic modifications are poorly understood.
METHODS
We used cholesterol-loaded TET2-deficient murine and embryonic stem cell–derived isogenic human macrophages to evaluate mechanisms of NLRP3 inflammasome activation in vitro and hypercholesterolemic Ldlr − / − mice modeling TET2 CH to assess the role of NLRP3 inflammasome activation in atherosclerosis.
RESULTS
Tet2 deficiency in murine macrophages acted synergistically with cholesterol loading in cell culture and with hypercholesterolemia in vivo to increase JNK1 (c-Jun N-terminal kinase 1) phosphorylation and NLRP3 inflammasome activation. The mechanism of JNK (c-Jun N-terminal kinase) activation in TET2 deficiency was increased promoter methylation and decreased expression of the JNK-inactivating dual-specificity phosphatase Dusp10 . Active Tet1-deadCas9–targeted editing of Dusp10 promoter methylation abolished cholesterol-induced inflammasome activation in Tet2 -deficient macrophages. Increased JNK1 signaling led to NLRP3 deubiquitylation and activation by the deubiquitinase BRCC3 ( BRCA1/BRCA2 -containing complex subunit 3). Accelerated atherosclerosis and neutrophil extracellular trap formation (NETosis) in Tet2 CH mice were reversed by holomycin, a BRCC3 deubiquitinase inhibitor, and also by hematopoietic deficiency of Abro1, an essential scaffolding protein in the BRCC3-containing cytosolic complex. Human TET2 − / − macrophages displayed increased JNK1 and NLRP3 inflammasome activation, especially after cholesterol loading, with reversal by holomycin treatment, indicating human relevance.
CONCLUSIONS
Hypercholesterolemia and TET2 deficiency converge on a common pathway of NLRP3 inflammasome activation mediated by JNK1 activation and BRCC3-mediated NLRP3 deubiquitylation, with potential therapeutic implications for the prevention of cardiovascular disease in TET2 CH.
... Apart from the sequential phosphorylation of the JNK cascade's components, the transmission of signals via this pathway is stringently regulated by several other processes, including phosphorylation, dephosphorylation, degradation, subcellular localization, and protein-protein interactions [7,[28][29][30][31][32]. These mechanisms are responsible for determining the specificity of the cascade by dictating the duration, strength, and substrate specificity of the signals. ...
The response of cells to extracellular signals is mediated by a variety of intracellular signaling pathways that determine stimulus-dependent cell fates. One such pathway is the cJun-N-terminal Kinase (JNK) cascade, which is mainly involved in stress-related processes. The cascade transmits its signals via a sequential activation of protein kinases, organized into three to five tiers. Proper regulation is essential for securing a proper cell fate after stimulation, and the mechanisms that regulate this cascade may involve the following: (1) Activatory or inhibitory phosphorylations, which induce or abolish signal transmission. (2) Regulatory dephosphorylation by various phosphatases. (3) Scaffold proteins that bring distinct components of the cascade in close proximity to each other. (4) Dynamic change of subcellular localization of the cascade’s components. (5) Degradation of some of the components. In this review, we cover these regulatory mechanisms and emphasize the mechanism by which the JNK cascade transmits apoptotic signals. We also describe the newly discovered PP2A switch, which is an important mechanism for JNK activation that induces apoptosis downstream of the Gq protein coupled receptors. Since the JNK cascade is involved in many cellular processes that determine cell fate, addressing its regulatory mechanisms might reveal new ways to treat JNK-dependent pathologies.
... The human genome contains three closely related JNK genes (JNK1, JNK2, and JNK3), with each gene encoding multiple isoforms [25]. While JNK1 and JNK2 are expressed in a variety of tissues, JNK3 expression has been reported to be limited mainly to neuronal tissue and, to a lesser extent, heart and testes [26,27]. ...
The c-Jun N-terminal kinase (JNK) family includes three proteins (JNK1-3) that regulate many physiological processes, including cell proliferation and differentiation, cell survival, and inflammation. Because of emerging data suggesting that JNK3 may play an important role in neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease, as well as cancer pathogenesis, we sought to identify JNK inhibitors with increased selectivity for JNK3. A panel of 26 novel tryptanthrin-6-oxime analogs was synthesized and evaluated for JNK1-3 binding (Kd) and inhibition of cellular inflammatory responses. Compounds 4d (8-methoxyindolo[2,1-b]quinazolin-6,12-dione oxime) and 4e (8-phenylindolo[2,1-b]quinazolin-6,12-dione oxime) had high selectivity for JNK3 versus JNK1 and JNK2 and inhibited lipopolysaccharide (LPS)-induced nuclear factor-κB/activating protein 1 (NF-κB/AP-1) transcriptional activity in THP-1Blue cells and interleukin-6 (IL-6) production by MonoMac-6 monocytic cells in the low micromolar range. Likewise, compounds 4d, 4e, and pan-JNK inhibitor 4h (9-methylindolo[2,1-b]quinazolin-6,12-dione oxime) decreased LPS-induced c-Jun phosphorylation in MonoMac-6 cells, directly confirming JNK inhibition. Molecular modeling suggested modes of binding interaction of these compounds in the JNK3 catalytic site that were in agreement with the experimental data on JNK3 binding. Our results demonstrate the potential for developing anti-inflammatory drugs based on these nitrogen-containing heterocyclic systems with selectivity for JNK3.
... The c-Jun N-terminal kinase (JNK) signaling pathway also regulates both physiological and pathological processes, such as neurodegenerative diseases, and inflammatory diseases. Dual specificity phosphatases (DUSPs) were found to regulate the JNK pathway by dephosphorylating their substrates, e.g., DUSP6 binds to JNK2/3 and thus inhibits JNK phosphorylation (Ha et al., 2019). LncRNA TCONS_00145741 could disrupt the interaction between DUSP6 and JNK and stabilize JNK phosphorylation, which suppressed M2 differentiation of microglia after ICH . ...
Intracerebral hemorrhage (ICH), a subtype of stroke, can lead to long-term disability and is one of the leading causes of death. Unfortunately, the effectiveness of pharmacological therapy for ICH is still uncertain. Long non-coding RNA (lncRNA) was defined as an RNA molecule that consists of more than 200 nt without translational activity. As a vital class of diverse molecules, lncRNAs are involved in developmental and pathological processes and have been attractive for decades. LncRNAs have also become potential targets for therapies, as they were massively identified and profiled. In particular, emerging evidence has revealed the critical role of lncRNAs in ICH while attempts were made to treat ICH via regulating lncRNAs. But the latest evidence remains to be summarized. Thus, in this review, we will summarize the recent advances in lncRNA in ICH, highlighting the regulatory role of lncRNAs and their potential as therapeutic targets.
