scholarly journals Nutrient transceptors physically interact with the yeast S6/Protein kinase B homolog, Sch9, a TOR kinase target

2021 ◽  
Author(s):  
Zhiqiang Zhang ◽  
Ines Cottignie ◽  
Griet Van Zeebroeck ◽  
Johan Thevelein
Keyword(s):  
Protein Kinase ◽  
Protein Kinase B ◽  
Specific Interaction ◽  
Nutrient Regulation ◽  
Cellular Processes ◽  
Peptide Microarrays ◽  
Tor Kinase ◽  
Yeast Homolog

Multiple starvation-induced, high-affinity nutrient transporters in yeast function as receptors for activation of the Protein Kinase A (PKA) pathway upon re-addition of their substrate. We now show that these transceptors may play more extended roles in nutrient regulation. The Gap1 amino acid, Mep2 ammonium, Pho84 phosphate and Sul1 sulfate transceptors physically interact in vitro and in vivo with the PKA-related Sch9 protein kinase, the yeast homolog of mammalian S6 Protein Kinase and Protein Kinase B. Sch9 is a phosphorylation target of TOR and well-known to affect nutrient-controlled cellular processes, such as growth rate. Mapping with peptide microarrays suggests specific interaction domains in Gap1 for Sch9 binding. Mutagenesis of the major domain affects the upstart of growth upon addition of L-citrulline to nitrogen-starved cells to different extents but apparently does not affect in vitro binding. It also does not correlate with the drop in L-citrulline uptake capacity or transceptor activation of the PKA target trehalase by the Gap1 mutant forms. Our results reveal a nutrient transceptor-Sch9-TOR axis in which Sch9 accessibility for phosphorylation by TOR may be affected by nutrient transceptor-Sch9 interaction under conditions of nutrient starvation or other environmental challenges.

Fucoidans from Cucumaria frondosa ameliorates renal interstitial fibrosis via inhibition of PI3K/Akt/NF-κB signaling pathway

2022 ◽  
Author(s):  
Zhuo-yue Song ◽  
Mengru Zhu ◽  
Jun Wu ◽  
Tian Yu ◽  
Yao Chen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Interstitial Fibrosis ◽  
Protein Kinase B ◽  
Nuclear Factor Κb ◽  
Nuclear Factor ◽  
Renal Interstitial Fibrosis ◽  
Cucumaria Frondosa

The effects of Cucumaria frondosa polysaccharides (CFP) on renal interstitial fibrosis via regulating phosphatidylinositol-3-hydroxykinase/protein kinase-B/Nuclear factor-κB (PI3K/AKT/NF-κB) signaling pathway were investigated in vivo and in vitro in this research. A...

scholarly journals Targeting redox regulatory site of protein kinase B impedes neutrophilic inflammation in lung injury

2018 ◽  
Author(s):  
Po-Jen Chen ◽  
I-Ling Ko ◽  
Chia-Lin Lee ◽  
Hao-Chun Hu ◽  
Fang-Rong Chang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Lung Injury ◽  
Inflammatory Responses ◽  
Protein Kinase B ◽  
Reduced Form ◽  
Human Neutrophils ◽  
Akt Inhibitor ◽  
Neutrophilic Inflammation

AbstractNeutrophil activation has a pathogenic effect in inflammatory diseases. Protein kinase B (PKB)/AKT regulates diverse cellular responses. However, the significance of AKT in neutrophilic inflammation is still not well understood. Here, we identified CLLV-1 as a novel AKT inhibitor. CLLV-1 inhibited respiratory burst, degranulation, chemotaxis, and AKT phosphorylation in activated human neutrophils and dHL-60 cells. Significantly, CLLV-1 blocked AKT activity and covalently reacted with AKT Cys310 in vitro. The AKT309-313 peptide-CLLV-1 adducts were determined by NMR or mass spectrometry assay. The alkylation agent-conjugated AKT (reduced form) level was also inhibited by CLLV-1. Additionally, CLLV-1 ameliorated lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. CLLV-1 acts as a covalent allosteric AKT inhibitor by targeting AKT Cys310 to restrain inflammatory responses in human neutrophils and LPS-induced ALI in vivo. Our findings provide a mechanistic framework for redox modification of AKT that may serve as a novel pharmacological target to alleviate neutrophilic inflammation.

scholarly journals Protein Kinase B Inactivation Is Associated with Magnolol-Enhanced Therapeutic Efficacy of Sorafenib in Hepatocellular Carcinoma In Vitro and In Vivo

Cancers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 87 ◽  
Author(s):  
Jiann-Hwa Chen ◽  
I-Tsang Chiang ◽  
Fei-Ting Hsu
Keyword(s):  
Hepatocellular Carcinoma ◽  
Protein Kinase ◽  
Protein Kinase B ◽  
Bioactive Compound ◽  
Critical Issue ◽  
Akt Inhibitor ◽  
Multikinase Inhibitor ◽  
Therapeutic Benefits

Although sorafenib, an oral multikinase inhibitor, was approved as a treatment drug of advance hepatocellular carcinoma (HCC), treatment efficacy still requires improvement. Searching for the adjuvant reagent for enhancing sorafenib efficacy remains as a critical issue. Sorafenib has been proved to suppress extracellular signal-regulated kinases (ERK) in HCC; however, protein kinase B (AKT) was not affected by it. Targeting AKT in combination with sorafenib could be an important breakthrough point of HCC treatment. Many herbal compounds and composite formulas have been shown to enhance anti-HCC activity of sorafenib. Magnolol is a bioactive compound extracted from the bark of the Magnolia officinalis and has been shown to induce apoptosis and inhibit cell invasion in HCC in vitro. However, whether magnolol sensitizes HCC to sorafenib is ambiguous. In this study, we indicated that magnolol significantly enhanced sorafenib-diminished tumor cell growth, expression of anti-apoptotic proteins, and migration/invasion ability compared to sorafenib alone. Magnolol significantly boosted sorafenib-induced extrinsic/intrinsic dependent apoptosis pathways in HCC. Notably sorafenib could not reduce protein level of AKT (Ser473), but expression of AKT (Ser473) was significantly decreased by magnolol or magnolol combined with sorafenib. LY294002 as specific AKT inhibitor was used to confirm that AKT inactivation may promote anticancer effect of sorafenib. Taken together, AKT inhibition is associated with magnolol-enhanced the therapeutic effect of sorafenib in HCC. We suggested magnolol as the potential adjuvant which may enhance therapeutic benefits of sorafenib in patients with HCC.

scholarly journals BRF1 Protein Turnover and mRNA Decay Activity Are Regulated by Protein Kinase B at the Same Phosphorylation Sites

2006 ◽  
Vol 26 (24) ◽  
pp. 9497-9507 ◽  
Author(s):  
Don Benjamin ◽  
Martin Schmidlin ◽  
Lu Min ◽  
Brigitte Gross ◽  
Christoph Moroni
Keyword(s):  
Protein Kinase ◽  
Mrna Decay ◽  
Protein Kinase B ◽  
Proteasomal Degradation ◽  
Mrna Levels ◽  
Cell Compartment ◽  
Protein Levels ◽  
Dependent Protein

ABSTRACT BRF1 posttranscriptionally regulates mRNA levels by targeting ARE-bearing transcripts to the decay machinery. We previously showed that protein kinase B (PKB) phosphorylates BRF1 at Ser92, resulting in binding to 14-3-3 and impairment of mRNA decay activity. Here we identify an additional regulatory site at Ser203 that cooperates in vivo with Ser92. In vitro kinase labeling and wortmannin sensitivity indicate that Ser203 phosphorylation is also performed by PKB. Mutation of both serines to alanine uncouples BRF1 from PKB regulation, leading to constitutive mRNA decay even in the presence of stabilizing signals. BRF1 protein is labile because of proteasomal degradation (half-life, <3 h) but becomes stabilized upon phosphorylation and is less stable in PKBα−/− cells. Surprisingly, phosphorylation-dependent protein stability is also regulated by Ser92 and Ser203, with parallel phosphorylation required at these sites. Phosphorylation-dependent binding to 14-3-3 is abolished only when both sites are mutated. Cell compartment fractionation experiments support a model in which binding to 14-3-3 sequesters BRF1 through relocalization and prevents it from executing its mRNA decay activity, as well as from proteasomal degradation, thereby maintaining high BRF1 protein levels that are required to reinstate decay upon dissipation of the stabilizing signal.

scholarly journals TCF21 inhibits tumor-associated angiogenesis and suppresses the growth of cholangiocarcinoma by targeting PI3K/Akt and ERK signaling

2019 ◽  
Vol 316 (6) ◽  
pp. G763-G773 ◽  
Author(s):  
Hua-Xin Duan ◽  
Bo-Wen Li ◽  
Xin Zhuang ◽  
Lu-Ting Wang ◽  
Qian Cao ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Transcription Factor ◽  
Protein Kinase ◽  
Cell Lines ◽  
Protein Kinase B ◽  
Tube Formation ◽  
Phosphatidylinositol 3 Kinase ◽  
Xenograft Growth

Tumor-associated angiogenesis plays a critical role in the pathogenesis of cholangiocarcinoma (CCA). In this study, we examined the biological effects and molecular mechanisms of transcription factor 21 (TCF21) on CCA-associated angiogenesis. TCF21 expression was compared between 15 pairs of peritumor normal tissues and CCA tissues and also between normal bile duct epithelial cells and two CCA cell lines (QBC-939 and TFK-1) using real-time PCR and Western blot. With the use of both CCA cell lines as the model system, we stably expressed TCF21 by lentiviral transduction (Lv-TCF21). In vivo, we monitored xenograft growth from different CCA cells, measured tumor-associated angiogenesis by histological analysis, and determined the expressions and circulatory levels of VEGFA and PDGF-BB by immunohistochemistry and ELISA, respectively. In vitro, we assessed the effects of conditioned medium collected from different CCA cells on the viability, migration, and tube formation of endothelial cells and explored the significance of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt), as well as ERK1/2 signaling in this process. TCF21 was significantly downregulated in CCA tissues or cell lines. Ectopic expression of TCF21 in CCA cells inhibited xenograft growth or tumor-associated angiogenesis in vivo and targeted the expression and secretion of proangiogenic factors, VEGFA and PDGF-BB. In vitro, the conditioned medium collected from Lv-TCF21 CCA cells significantly reduced the viability, migration, and tube formation of endothelial cells. On the molecular level, the targeting of PI3K/Akt and ERK1/2 signaling mediated the anti-angiogenic activity of TCF21. TCF21 presents growth-inhibitory and anti-angiogenic activities, and thus the elevation of TCF21 expression may provide therapeutic benefits for CCA. NEW & NOTEWORTHY Transcription factor 21 (TCF21) is downregulated in cholangiocarcinoma (CCA) tissues or cells. TCF21 inhibits the growth of xenografts derived from CCA cells. TCF21 suppresses in vivo tumor-associated angiogenesis. TCF21 targets expression and production of proangiogenic factors from CCA cells. The targeting of phosphatidylinositol 3-kinase/protein kinase B and ERK1/2 signaling mediates the anti-angiogenesis of TCF21.

scholarly journals Activation of protein kinase B β and γ isoforms by insulin in vivo and by 3-phosphoinositide-dependent protein kinase-1 in vitro: comparison with protein kinase B α

1998 ◽  
Vol 331 (1) ◽  
pp. 299-308 ◽  
Author(s):  
Kay S. WALKER ◽  
Maria DEAK ◽  
Andrew PATERSON ◽  
Kevin HUDSON ◽  
Philip COHEN ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Protein Kinase B ◽  
Rat Hepatocytes ◽  
Dependent Protein Kinase ◽  
L6 Myotubes ◽  
Dependent Protein ◽  
Stimulation Of

The regulatory and catalytic properties of the three mammalian isoforms of protein kinase B (PKB) have been compared. All three isoforms (PKBα, PKBβ and PKBγ) were phosphorylated at similar rates and activated to similar extents by 3-phosphoinositide-dependent protein kinase-1 (PDK1). Phosphorylation and activation of each enzyme required the presence of PtdIns(3,4,5)P3 or PtdIns(3,4)P2, as well as PDK1. The activation of PKBβ and PKBγ by PDK1 was accompanied by the phosphorylation of the residues equivalent to Thr308 in PKBα, namely Thr309 (PKBβ) and Thr305 (PKBγ). PKBγ which had been activated by PDK1 possessed a substrate specificity identical with that of PKBα and PKBβ towards a range of peptides. The activation of PKBγ and its phosphorylation at Thr305 was triggered by insulin-like growth factor-1 in 293 cells. Stimulation of rat adipocytes or rat hepatocytes with insulin induced the activation of PKBα and PKBβ with similar kinetics. After stimulation of adipocytes, the activity of PKBβ was twice that of PKBα, but in hepatocytes PKBα activity was four-fold higher than PKBβ. Insulin induced the activation of PKBα in rat skeletal muscle in vivo, with little activation of PKBβ. Insulin did not induce PKBγ activity in adipocytes, hepatocytes or skeletal muscle, but PKBγ was the major isoform activated by insulin in rat L6 myotubes (a skeletal-muscle cell line).

scholarly journals Regulation of Protein Kinase B Tyrosine Phosphorylation by Thyroid-Specific Oncogenic RET/PTC Kinases

2005 ◽  
Vol 19 (11) ◽  
pp. 2748-2759 ◽  
Author(s):  
Hye Sook Jung ◽  
Dong Wook Kim ◽  
Young Suk Jo ◽  
Hyo Kyun Chung ◽  
Jung Hun Song ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Signaling Pathways ◽  
Tyrosine Phosphorylation ◽  
Protein Kinase B ◽  
Cellular Transformation ◽  
Forkhead Transcription Factor ◽  
Src Tyrosine Kinase

Abstract Papillary thyroid carcinoma (PTC) is a heterogenous disorder characterized by unique gene rearrangements and gene mutations that activate signaling pathways responsible for cellular transformation, survival, and antiapoptosis. Activation of protein kinase B (PKB) and its downstream signaling pathways appears to be an important event in thyroid tumorigenesis. In this study, we found that the thyroid-specific oncogenic RET/PTC tyrosine kinase is able to phosphorylate PKB in vitro and in vivo. RET/PTC-transfected cells showed tyrosine phosphorylation of endogenous and exogenous PKB, which was independent of phosphorylation of T308 and S473 regulated by the upstream kinases phosphoinositide-dependent kinase-1 and -2, respectively. The PKB Y315 residue, which is known to be phosphorylated by Src tyrosine kinase, was also a major site of phosphorylation by RET/PTC. RET/PTC-mediated tyrosine phosphorylation results in the activation of PKB kinase activity. The activation of PKB by RET/PTC blocked the activity of the forkhead transcription factor, FKHRL1, but a Y315F mutant of PKB failed to inhibit FKHRL1 activity. In summary, these observations suggest that RET/PTC is able to phosphorylate the Y315 residue of PKB, an event that results in maximal activation of PKB for RET/PTC-induced thyroid tumorigenesis.

scholarly journals In vitro and In vivo Activity of Novel Small-Molecule Inhibitors Targeting the Pleckstrin Homology Domain of Protein Kinase B/AKT

2009 ◽  
Vol 69 (12) ◽  
pp. 5073-5081 ◽  
Author(s):  
Sylvestor A. Moses ◽  
M. Ahad Ali ◽  
Song Zuohe ◽  
Lei Du-Cuny ◽  
Li Li Zhou ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Small Molecule ◽  
Small Molecule Inhibitors ◽  
Protein Kinase B ◽  
Pleckstrin Homology Domain ◽  
Pleckstrin Homology

scholarly journals Protein Kinase B and Extracellular Signal-Regulated Kinase Inactivation is Associated with Regorafenib-Induced Inhibition of Osteosarcoma Progression In Vitro and In Vivo

2019 ◽  
Vol 8 (6) ◽  
pp. 900 ◽  
Author(s):  
Po-Jung Pan ◽  
Yu-Chang Liu ◽  
Fei-Ting Hsu
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Protein Kinase B ◽  
Akt Inhibitor ◽  
Inhibitory Protein ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Apoptosis Protein

Osteosarcoma is the most common type of bone cancer. Multimodality treatment involving chemotherapy, radiotherapy and surgery is not effective enough to control osteosarcoma. Regorafenib, the oral multi-kinase inhibitor, has been shown to have positive efficacy on disease progression delay in chemotherapy resistant osteosarcoma patients. However anti-cancer effect and mechanism of regorafenib in osteosarcoma is ambiguous. Thus, the aim of this study is to investigate the efficacy and molecular mechanism of regorafenib on osteosarcoma in vitro and in vivo. Human osteosarcomas U-2 OS or MG-63 were treated with regorafenib, miltefosine (protein kinase B (AKT) inhibitor), or PD98059 (mitogen-activated protein/extracellular signal-regulated kinase (MEK) pathway inhibitor) for 24 or 48 h. Cell viability, apoptotic signaling transduction, tumor invasion, expression of tumor progression-associated proteins and tumor growth after regorafenib treatment were assayed by MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, flow cytometry, transwell assay, Western blotting assay and in vivo animal experiment, respectively. In these studies, we also indicated that regorafenib suppressed cell growth by prompting apoptosis of osteosarcoma cells, which is mediated through inactivation of ERK and AKT signaling pathways. After regorafenib treatment, downregulation of related genes in invasion (vascular endothelial growth factor (VEGF) and matrix metallopeptidase 9 (MMP-9)), proliferation (CyclinD1) and anti-apoptosis (X-linked inhibitor of apoptosis protein (XIAP), myeloid cell leukemia-1 (MCL-1), and cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (C-FLIP)) were found. Moreover, upregulation of caspase-3 and caspase-8 cleavage were also observed. In sum, we suggest that regorafenib has potential to suppress osteosarcoma progression via inactivation of AKT and ERK mediated signaling pathway.

scholarly journals Phosphorylation Targets of DNA-PK and Their Role in HIV-1 Replication

Cells ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1907
Author(s):  
Andrey Anisenko ◽  
Marina Kan ◽  
Olga Shadrina ◽  
Anna Brattseva ◽  
Marina Gottikh
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Enrichment Analysis ◽  
Functional Enrichment Analysis ◽  
Functional Enrichment ◽  
Dna Double Strand Breaks ◽  
Cellular Processes ◽  
Hiv 1

The DNA dependent protein kinase (DNA-PK) is a trimeric nuclear complex consisting of a large protein kinase and the Ku heterodimer. The kinase activity of DNA-PK is required for efficient repair of DNA double-strand breaks (DSB) by non-homologous end joining (NHEJ). We also showed that the kinase activity of DNA-PK is essential for post-integrational DNA repair in the case of HIV-1 infection. Besides, DNA-PK is known to participate in such cellular processes as protection of mammalian telomeres, transcription, and some others where the need for its phosphorylating activity is not clearly elucidated. We carried out a systematic search and analysis of DNA-PK targets described in the literature and identified 67 unique DNA-PK targets phosphorylated in response to various in vitro and/or in vivo stimuli. A functional enrichment analysis of DNA-PK targets and determination of protein–protein associations among them were performed. For 27 proteins from these 67 DNA-PK targets, their participation in the HIV-1 life cycle was demonstrated. This information may be useful for studying the functioning of DNA-PK in various cellular processes, as well as in various stages of HIV-1 replication.

Sign in / Sign up

Export Citation Format

Share Document