ORCID Profile
0000-0002-0588-8016
Current Organisations
University of Southampton
,
Flinders University
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Publisher: Springer Science and Business Media LLC
Date: 31-07-2010
DOI: 10.1007/S11010-010-0541-3
Abstract: The modification of free amino groups on proteins, lipids, and nucleic acids by non-enzymatic glycosylation produce a variety of complex structures named advanced glycation end products (AGEs). Glycation of these molecules participate in the development of diabetic complications and related diseases. Diabetes mellitus is characterized by short-term metabolic changes in lipid and protein metabolism, and long-term irreversible changes in vascular and connective tissue. AGEs are directly implicated in the development of chronic complications in diabetes such as nephropathy, rethinopathy, neuropathy, and other related diseases such as atherosclerosis, heart disease, stroke, and peripheral vascular disease. In this review, we aim to explain how glycation occurs in different molecules and what the pathological consequence of AGE formation in diabetes mellitus and other diseases are.
Publisher: American Association for Cancer Research (AACR)
Date: 07-2015
DOI: 10.1158/1535-7163.MCT-14-1048
Abstract: Cambogin is a polycyclic polyprenylated acylphoroglucinol (PPAP) from the Garcinia genus, which has been used traditionally for cancer treatment across Southeastern Asia. In this study, we found that cambogin inhibited breast cancer cell proliferation and induced cell apoptosis in vitro. Cambogin induced the activation of the caspase-independent mitochondrial apoptotic pathway, as indicated by an increase in the ratio of Bax/Bcl-2 and the nuclear translocation of apoptosis inducing factor (AIF). Two-dimensional gel electrophoresis and mass spectrometry revealed that the expression of proteins involving in the radical oxygen species (ROS) pathway was among the most affected upon cambogin treatment. Cambogin enhanced cellular ROS production, and induced the activation of the ASK1–MKK4/MKK7–JNK/SAPK signaling pathway. Pretreatment with ROS scavenger N-acetylcysteine (NAC), an antioxidant, or the JNK inhibitor SP600125 was able to restore cell viability in the presence of cambogin. Importantly, cambogin treatment led to the activation of activating transcription factor-2 (ATF-2) and the trimethylation of histone H3K9 in the activator protein 1 (AP-1) binding region of the Bcl-2 gene promoter. Finally, cambogin exhibited a potential antitumor effect in MCF-7 breast cancer xenografts without apparent toxicity. Taken in conjunction, the present study indicates that cambogin can induce breast adenocarcinoma cell apoptosis and therefore represents therapeutic potential for cancer treatment. Mol Cancer Ther 14(7) 1738–49. ©2015 AACR.
Publisher: Springer Science and Business Media LLC
Date: 13-02-2020
DOI: 10.1186/S12964-020-0528-Y
Abstract: Eukaryotic elongation factor-2 kinase (eEF2K) is a Ca 2+ /calmodulin (CaM)-dependent protein kinase that inhibits protein synthesis. However, the role of eEF2K in cancer development was reported paradoxically and remains to be elucidated. Herein, A549 cells with eEF2K depletion or overexpression by stably transfected lentivirus plasmids were used in vitro and in vivo study. MTT and colony assays were used to detect cell proliferation and growth. Extracellular glucose and lactate concentration were measured using test kit. Immunoblot and co-immunoprecipitation assays were used to examine the molecular biology changes and molecular interaction in these cells. LC-MS/MS analysis and [γ- 32 P] ATP kinase assay were used to identify combining protein and phosphorylation site. Nude mice was utilized to study the correlation of eEF2K and tumor growth in vivo. We demonstrated that eEF2K inhibited lung cancer cells proliferation and affected the inhibitory effects of EGFR inhibitor gefitinib. Mechanistically, we showed that eEF2K formed a complex with PKM2 and STAT3, thereby phosphorylated PKM2 at T129, leading to reduced dimerization of PKM2. Subsequently, PKM2 impeded STAT3 phosphorylation and STAT3-dependent c-Myc expression. eEF2K depletion promoted the nuclear translocation of PKM2 and increased aerobic glycolysis reflected by increased lactate secretion and glucose. Our findings define a novel mechanism underlying the regulation of cancer cell proliferation by eEF2K independent of its role in protein synthesis, disclosing the erse roles of eEF2K in cell biology, which lays foundation for the development of new anticancer therapeutic strategies.
Publisher: Elsevier BV
Date: 06-2009
DOI: 10.1016/J.JMB.2009.04.020
Abstract: Ribosomal protein S6 (rpS6) is phosphorylated in vivo by isoforms of p70 S6 protein kinase and p90 ribosomal S6 kinase, and there is good evidence that it plays a positive role in controlling pancreatic beta-cell size and function. In this report, we demonstrate in the pancreatic beta-cell line MIN6 (mouse insulinoma cell line 6) and islets of Langerhans that agents which stimulate increases in cAMP, such as glucagon-like peptide-1 and forskolin, lead to the phosphorylation of rpS6 at Ser235/Ser236 independently of the activation of the currently known in vivo rpS6 kinases via a pathway that is sensitive to inhibitors of cAMP-dependent protein kinase [protein kinase A (PKA)]. This cAMP-dependent rpS6 kinase activity is also sensitive to PKI in vitro, and PKA exclusively phosphorylates recombinant rpS6 on Ser235/Ser236 in vitro. With these data taken together, we conclude that PKA can phosphorylate rpS6 exclusively at Ser235/Ser236 in vivo in pancreatic beta-cells, thus providing a potentially important link between cAMP signalling and the regulation of protein synthesis. Lastly, we provide evidence that PKA is also likely to phosphorylate rpS6 on Ser235/Ser236 in vivo in a number of other mammalian cell types.
Publisher: Springer Science and Business Media LLC
Date: 04-2021
Publisher: Cold Spring Harbor Laboratory
Date: 06-09-2020
DOI: 10.1101/2020.09.05.284661
Abstract: The mechanistic target of rapamycin complex 1 (mTORC1) is an important regulator of cellular metabolism that is commonly hyperactivated in cancer. Recent cancer genome screens have identified multiple mutations in Ras-homolog enriched in brain (Rheb), the primary activator of mTORC1, that might act as driver oncogenes by causing hyperactivation of mTORC1. Here, we show that a number of recurrently occurring Rheb mutants drive hyperactive mTORC1 signalling through differing levels of insensitivity to the primary inactivator of Rheb, Tuberous Sclerosis Complex. We show that two activated mutants, Rheb-T23M and E40K, strongly drive increased cell growth, proliferation and anchorage-independent growth resulting in enhanced tumour growth in vivo . Proteomic analysis of cells expressing the mutations revealed, surprisingly, that these two mutants promote distinct oncogenic pathways with Rheb-T23M driving metabolic reprogramming and an increased rate of glycolysis, while Rheb-E40K regulates the translation factor eEF2 and autophagy, likely through a differential interaction with AMPK. Our findings suggest that unique ‘bespoke’ combination therapies may be utilised to treat cancers according to which Rheb mutant they harbour.
Publisher: Impact Journals, LLC
Date: 13-07-2016
Publisher: Wiley
Date: 27-12-2017
DOI: 10.1002/IJC.31210
Abstract: Eukaryotic elongation factor 2 kinase (eEF2K) negatively regulates the elongation phase of mRNA translation and hence protein synthesis. Increasing evidence indicates that eEF2K plays an important role in the survival and migration of cancer cells and in tumor progression. As demonstrated by two-dimensional wound-healing and three-dimensional transwell invasion assays, knocking down or inhibiting eEF2K in cancer cells impairs migration and invasion of cancer cells. Conversely, exogenous expression of eEF2K or knocking down eEF2 (the substrate of eEF2K) accelerates wound healing and invasion. Importantly, using LC-HDMS
Publisher: Springer Science and Business Media LLC
Date: 23-03-2010
DOI: 10.1007/S11010-010-0434-5
Abstract: Advanced glycation end-products (AGEs) are heterogeneous groups of compounds that result from the non-enzymatic reaction of reducing sugars with free amino groups of biological molecules such as proteins, lipids, and nucleic acids. A large number of studies have been focused on AGEs metabolism, analysis, treatments, and their implications in the pathogenesis of diseases, especially in diabetes mellitus. Here, we review recent advances in the understanding of pathological complications caused by the production of AGEs. We provide an overview of the most important issues published within this area in last years we also present the number of scientific papers related to AGEs available since 1950 until 2008 in the most important fields including metabolism, physiology, and pharmacology, thus as analytical methods for AGE detection and quantification and studies carried out in human body fluids. Data were collected from ovidSP.
Publisher: Springer Science and Business Media LLC
Date: 28-05-2019
Publisher: Portland Press Ltd.
Date: 02-04-2015
DOI: 10.1042/BJ20150089
Abstract: Eukaryotic elongation factor 2 kinase (eEF2K) is activated under erse stress conditions, where it aids cell survival but also undergoes degradation. We show that degradation of eEF2K requires it to be in an active state but does not require its activity.
Publisher: Wiley
Date: 27-09-2020
DOI: 10.1111/JNC.15178
Publisher: Elsevier BV
Date: 05-2019
Publisher: MDPI AG
Date: 27-11-2017
Publisher: Portland Press Ltd.
Date: 20-03-2015
DOI: 10.1042/BJ20141066
Abstract: This study shows, based on genetic data and a new pharmacological agent, that the MAP kinase-interacting kinases are required for efficient migration of cancer cells. These kinases may therefore play a role in processes associated with tumour metastasis.
Publisher: Elsevier BV
Date: 08-2021
DOI: 10.1016/J.CELREP.2021.109564
Abstract: Studies investigating whether there is a causative link between the gut microbiota and lifespan have largely been restricted to invertebrates or to mice with a reduced lifespan because of a genetic deficiency. We investigate the effect of early-life antibiotic exposure on otherwise healthy, normal chow-fed, wild-type mice, monitoring these mice for more than 700 days in comparison with untreated control mice. We demonstrate the emergence of two different low- ersity community types, post-antibiotic microbiota (PAM) I and PAM II, following antibiotic exposure. PAM II but not PAM I mice have impaired immunity, increased insulin resistance, and evidence of increased inflammaging in later life as well as a reduced lifespan. Our data suggest that differences in the composition of the gut microbiota following antibiotic exposure differentially affect host health and longevity in later life.
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 04-2016
Publisher: F1000 Research Ltd
Date: 25-08-2016
DOI: 10.12688/F1000RESEARCH.9207.1
Abstract: The mammalian target of rapamycin, mTOR, plays key roles in cell growth and proliferation, acting at the catalytic subunit of two protein kinase complexes: mTOR complexes 1 and 2 (mTORC1/2). mTORC1 signaling is switched on by several oncogenic signaling pathways and is accordingly hyperactive in the majority of cancers. Inhibiting mTORC1 signaling has therefore attracted great attention as an anti-cancer therapy. However, progress in using inhibitors of mTOR signaling as therapeutic agents in oncology has been limited by a number of factors, including the fact that the classic mTOR inhibitor, rapamycin, inhibits only some of the effects of mTOR the existence of several feedback loops and the crucial importance of mTOR in normal physiology.
Publisher: Informa UK Limited
Date: 11-2014
DOI: 10.1128/MCB.01035-14
Publisher: The Company of Biologists
Date: 03-2020
DOI: 10.1242/JCS.238014
Abstract: It has become increasingly evident that T cell functions are subject to translational control in addition to transcriptional regulation. Here, by using live imaging of CD8+ T cells isolated from the Lifeact-EGFP mouse, we show that T cells exhibit a gain in fluorescence intensity following engagement of cognate tumour target cells. The GFP signal increase is governed by Erk1/2-dependent distal T cell receptor (TCR) signalling and its magnitude correlates with IFN-γ and TNF-α production, which are hallmarks of T cell activation. Enhanced fluorescence was due to increased translation of Lifeact-EGFP protein, without an associated increase in its mRNA. Activation-induced gains in fluorescence were also observed in naïve and CD4+ T cells from the Lifeact-EGFP reporter, and were readily detected by both flow cytometry and live cell microscopy. This unique, translationally controlled reporter of effector T cell activation simultaneously enables tracking of cell morphology, F-actin dynamics and activation state in in idual migrating T cells. It is a valuable addition to the limited number of reporters of T cell dynamics and activation, and opens the door to studies of translational activity and heterogeneities in functional T cell responses in situ.
Publisher: Portland Press Ltd.
Date: 31-07-2020
DOI: 10.1042/BCJ20200433
Abstract: The mitogen-activated protein kinase (MAPK)-interacting kinases (MNKs) are serine/threonine protein kinases that are activated by the ERK1/2 (extracellular regulated kinase) and p38α/β MAPK pathways. The MNKs have previously been implicated in metabolic disease and shown to mediate diet-induced obesity. In particular, knockout of MNK2 in mice protects from the weight gain induced by a high-fat diet. These and other data suggest that MNK2 regulates the expansion of adipose tissue (AT), a stable, long-term energy reserve that plays an important role in regulating whole-body energy homeostasis. Using the well-established mouse 3T3-L1 in vitro model of adipogenesis, the role of the MNKs in adipocyte differentiation and lipid storage was investigated. Inhibition of MNK activity using specific inhibitors failed to impair adipogenesis or lipid accumulation, suggesting that MNK activity is not required for adipocyte differentiation and does not regulate lipid storage. However, small-interfering RNA (siRNA) knock-down of MNK2 did reduce lipid accumulation and regulated the levels of two major lipogenic transcriptional regulators, ChREBP (carbohydrate response element-binding protein) and LPIN1 (Lipin-1). These factors are responsible for controlling the expression of genes for proteins involved in de novo lipogenesis and triglyceride synthesis. The knock-down of MNK2 also increased the expression of hormone-sensitive lipase which catalyses the breakdown of triglyceride. These findings identify MNK2 as a regulator of adipocyte metabolism, independently of its catalytic activity, and reveal some of the mechanisms by which MNK2 drives AT expansion. The development of an MNK2-targeted therapy may, therefore, be a useful intervention for reducing weight caused by excessive nutrient intake.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 08-02-2012
Publisher: Wiley
Date: 22-07-2020
DOI: 10.1002/IJC.32560
Abstract: Hepatocellular carcinoma (HCC) is an aggressive malignancy with increasing mortality in China. Angiogenesis is crucial for tumor formation, development and metastasis in HCC. Previous studies indicated that high expression levels of elongation factor 2 kinase (eEF2K), a protein kinase that negatively regulates the elongation stage of translation, were associated with poor prognosis of HCC. Here, we show that pharmacological inhibition or knockdown of eEF2K in highly metastatic liver cancer cells inhibits their colony forming and migratory capacities, as well as reducing their invasiveness. Importantly, knocking down eEF2K by lentiviral directed shRNA prevented tumor growth and angiogenesis of HCC in mice. Silencing of eEF2K in endothelial cells (HUVECs) led to a reduction in vascularization, evidenced by a decrease in capillary-like structures in the matrigel. Notably, knocking down eEF2K reduced the expression of angiogenesis-related growth factors in liver cancer cells and the expression of growth factor receptors on HUVECs, and thus restricted signaling crosstalk that promotes angiogenesis between HCC cells and endothelial cells. We also showed that silencing of eEF2K effectively reduced protein levels of SP1/KLF5 transcription factors and hence decreased the levels of bound SP1/KLF5 to the VEGF promoter, resulted in a decrease in VEGF mRNA expression. Knocking down eEF2K also led to a striking decrease in the phosphorylation of PI3K/Akt and STAT3, indicating inactivation of these tumorigenic pathways. Taken together, our data suggest that eEF2K contributes to angiogenesis and tumor progression in HCC via SP1/KLF5-mediated VEGF expression, as well as the subsequent stimulation of PI3K/Akt and STAT3 signaling.
Publisher: Portland Press Ltd.
Date: 09-12-2016
DOI: 10.1042/BCJ20160845
Abstract: Many protein-based biotherapeutics are produced in cultured Chinese hamster ovary (CHO) cell lines. Recent reports have demonstrated that translation of recombinant mRNAs and global control of the translation machinery via mammalian target of rapamycin (mTOR) signalling are important determinants of the amount and quality of recombinant protein such cells can produce. mTOR complex 1 (mTORC1) is a master regulator of cell growth/ ision, ribosome biogenesis and protein synthesis, but the relationship between mTORC1 signalling, cell growth and proliferation and recombinant protein yields from mammalian cells, and whether this master regulating signalling pathway can be manipulated to enhance cell biomass and recombinant protein production (rPP) are not well explored. We have investigated mTORC1 signalling and activity throughout batch culture of a panel of sister recombinant glutamine synthetase-CHO cell lines expressing different amounts of a model monoclonal IgG4, to evaluate the links between mTORC1 signalling and cell proliferation, autophagy, recombinant protein expression, global protein synthesis and mRNA translation initiation. We find that the expression of the mTORC1 substrate 4E-binding protein 1 (4E-BP1) fluctuates throughout the course of cell culture and, as expected, that the 4E-BP1 phosphorylation profiles change across the culture. Importantly, we find that the eIF4E/4E-BP1 stoichiometry positively correlates with cell productivity. Furthermore, eIF4E amounts appear to be co-regulated with 4E-BP1 amounts. This may reflect a sensing of either change at the mRNA level as opposed to the protein level or the fact that the phosphorylation status, as well as the amount of 4E-BP1 present, is important in the co-regulation of eIF4E and 4E-BP1.
Publisher: Informa UK Limited
Date: 05-2015
DOI: 10.1128/MCB.00012-15
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.BBAMCR.2017.06.011
Abstract: Alzheimer's disease is the most important cause of dementia but there is no therapy that has been demonstrated to stop or slow disease progression. Amyloid precursor protein (APP) is the source of amyloid-β (Aβ), which aggregates in Alzheimer's disease to form toxic oligomeric species. The endo-lysosomal system can clear APP and Aβ from the cell if these molecular species are trafficked through to the lysosome. Currently, there are no easy methods available for the analysis of lysosomal APP trafficking. We therefore generated a fusion protein (tandem-fluorescent, or tf-APP) that allows detection of changes in APP trafficking using accessible techniques such as flow cytometry. This permits rapid analysis or screening of genes and compounds that alter APP processing in the cell. Using our novel molecular probe, we determined that starvation induces trafficking of APP and APP-carboxy-terminal fragments (APP-CTFs) to the degradative endo-lysosomal network. In line with this finding, suppression of mTOR signalling using AZD8055 also strongly induced trafficking of APP to the endo-lysosomal system. Remarkably, activation of mTOR signalling via RHEB over-expression inhibited the starvation-induced autophagy but did not affect trafficking of tf-APP. These results show tf-APP can be used to determine how APP is trafficked through the lysosomal system of the cell. This molecular probe is therefore useful for determining the molecular mechanism behind the commitment of APP to the degradative pathway or for screening compounds that can induce this effect. This is important as clearance of APP and APP-CTF provides an important potential therapeutic strategy for Alzheimer's disease.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.CUB.2019.01.029
Abstract: Maintaining accuracy during protein synthesis is crucial to avoid producing misfolded and/or non-functional proteins. The target of rapamycin complex 1 (TORC1) pathway and the activity of the protein synthesis machinery are known to negatively regulate lifespan in many organisms, although the precise mechanisms involved remain unclear. Mammalian TORC1 signaling accelerates the elongation stage of protein synthesis by inactivating eukaryotic elongation factor 2 kinase (eEF2K), which, when active, phosphorylates and inhibits eEF2, which mediates the movement of ribosomes along mRNAs, thereby slowing down the rate of elongation. We show that eEF2K enhances the accuracy of protein synthesis under a range of conditions and in several cell types. For ex le, our data reveal it links mammalian (m)TORC1 signaling to the accuracy of translation. Activation of eEF2K decreases misreading or termination readthrough errors during elongation, whereas knocking down or knocking out eEF2K increases their frequency. eEF2K also promotes the correct recognition of start codons in mRNAs. Reduced translational fidelity is known to correlate with shorter lifespan. Consistent with this, deletion of the eEF2K ortholog or other factors implicated in translation fidelity in Caenorhabditis elegans decreases lifespan, and eEF2K is required for lifespan extension induced by nutrient restriction. Our data uncover a novel mechanism linking nutrient supply, mTORC1 signaling, and the elongation stage of protein synthesis, which enhances the accuracy of protein synthesis. Our data also indicate that modulating translation elongation and its fidelity affects lifespan.
Publisher: eLife Sciences Publications, Ltd
Date: 12-08-2021
DOI: 10.7554/ELIFE.62592
Abstract: Alterations to the androgen receptor (AR) signalling axis and cellular metabolism are hallmarks of prostate cancer. This study provides insight into both hallmarks by uncovering a novel link between AR and the pentose phosphate pathway (PPP). Specifically, we identify 6-phosphogluoconate dehydrogenase ( 6PGD ) as an androgen-regulated gene that is upregulated in prostate cancer. AR increased the expression of 6PGD indirectly via activation of sterol regulatory element binding protein 1 (SREBP1). Accordingly, loss of 6PGD, AR or SREBP1 resulted in suppression of PPP activity as revealed by 1,2- 13 C 2 glucose metabolic flux analysis. Knockdown of 6PGD also impaired growth and elicited death of prostate cancer cells, at least in part due to increased oxidative stress. We investigated the therapeutic potential of targeting 6PGD using two specific inhibitors, physcion and S3, and observed substantial anti-cancer activity in multiple models of prostate cancer, including aggressive, therapy-resistant models of castration-resistant disease as well as prospectively collected patient-derived tumour explants. Targeting of 6PGD was associated with two important tumour-suppressive mechanisms: first, increased activity of the AMP-activated protein kinase (AMPK), which repressed anabolic growth-promoting pathways regulated by acetyl-CoA carboxylase 1 (ACC1) and mammalian target of rapamycin complex 1 (mTORC1) and second, enhanced AR ubiquitylation, associated with a reduction in AR protein levels and activity. Supporting the biological relevance of positive feedback between AR and 6PGD, pharmacological co-targeting of both factors was more effective in suppressing the growth of prostate cancer cells than single-agent therapies. Collectively, this work provides new insight into the dysregulated metabolism of prostate cancer and provides impetus for further investigation of co-targeting AR and the PPP as a novel therapeutic strategy.
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.CELLSIG.2013.06.013
Abstract: The receptor for advanced glycation end-product (RAGE) is the signal transduction receptor which senses a variety of signalling molecules including advanced glycation end products (AGEs), HMGB1, S100/calgranulins, β-amyloid, phosphatidylserine, C3a and advanced oxidation protein products (AOPPs). It is usually abnormally up-regulated and plays crucial roles during the development of many human diseases such as diabetes, cardiovascular diseases, osteoarthritis and cancer. RAGE regulates a number of cell processes of pivotal importance like inflammation, apoptosis, proliferation and autophagy. Therapeutic strategies to block RAGE may represent great therapeutic potentials and therefore it has been under extensive investigation during the last decade. Accordingly, there is a growing interest of unraveling the intracellular signalling pathways by which RAGE controls these disease-related processes. Early studies are mainly focused on inflammatory pathways involving the NFκB and the MAPK pathways. Nevertheless, many novel signalling pathways implicated in other cell processes, such as autophagy, have also recently been found to be activated upon RAGE stimulation and contribute to the detrimental effects of RAGE. In this review, we aim to provide a comprehensive summary of previous and recent studies relating to the complex molecular network of RAGE signalling, with a particular emphasis on RAGE transgenic mouse models.
Publisher: Elsevier
Date: 2021
Publisher: Elsevier BV
Date: 10-2016
Publisher: Wiley
Date: 26-07-2016
DOI: 10.1016/J.IJDEVNEU.2016.07.007
Abstract: Human adult dental pulp stem cells (DPSC) are a heterogeneous stem cell population, which are able to differentiate down neural, chondrocyte, osteocyte and adipocyte lineages. We studied the expression pattern of p75 neurotrophin receptors (p75NTR), a marker of neural stem cells, within human DPSC populations from eight donors. p75NTR are expressed at low levels (<10%) in DPSC. Importantly, p75(+) DPSC represent higher expression levels of SOX1 (neural precursor cell marker), SOX2 (cell pluripotency marker) and nestin (neural stem cell marker) in comparison to p75(-) DPSC. Our results suggest that p75(+) hDPSC may denote a subpopulation with greater neurogenic potential.
Publisher: Springer Science and Business Media LLC
Date: 11-2013
DOI: 10.1038/NCB2877
Abstract: The mTOR protein kinase controls anabolic processes as part of mTOR complexes 1 and 2 (mTORC1 and mTORC2). The two complexes are now shown to be involved in a negative feedback regulatory mechanism, in which mTORC1 stimulation inactivates mTORC2 through the inhibitory phosphorylation of the mTORC2 component Sin1.
Publisher: Wiley
Date: 14-04-2021
DOI: 10.1002/BIT.27748
Abstract: Monoclonal antibodies (mAbs) are high value agents used for disease therapy (“biologic drugs”) or as diagnostic tools which are widely used in the healthcare sector. They are generally manufactured in mammalian cells, in particular Chinese hamster ovary (CHO) cells cultured in defined media, and are harvested from the medium. Rheb is a small GTPase which, when bound to GTP, activates mechanistic target of rapamycin complex 1, a protein kinase that drives anabolic processes including protein synthesis and ribosome biogenesis. Here, we show that certain constitutively active mutants of Rheb drive faster protein synthesis in CHO cells and increase the expression of proteins involved in the processing of secreted proteins in the endoplasmic reticulum, which expands in response to expression of Rheb mutants. Active Rheb mutants, in particular Rheb[T23M], drive increased cell number under serum‐free conditions similar to those used in the biotechnology industry. Rheb[T23M] also enhances the expression of the reporter protein luciferase and, especially strongly, the secreted Gaussia luciferase. Moreover, Rheb[T23M] markedly (2–3 fold) enhances the amount of this luciferase and of a model immunoglobulin secreted into the medium. Our data clearly demonstrate that expressing Rheb[T23M] in CHO cells provides a simple approach to promoting their growth in defined medium and the production of secreted proteins of high commercial value.
Publisher: Bioscientifica
Date: 08-2014
DOI: 10.1530/JME-13-0200
Abstract: Glucagon-like peptide 1 receptor (GLP1R) agonists, such as exendin-4, potentiate glucose-stimulated insulin secretion and are currently used in the management of type 2 diabetes. Interestingly, GLP1R agonists also have the ability to augment β-cell mass. In this report, we provide evidence that in the presence of glucose, exendin-4 stimulates rodent islet cell DNA replication via the activation of ribosomal protein S6 kinase 1 (S6K1) and that this is mediated by the protein kinase B (PKB)-dependent activation of mTOR complex 1 (mTORC1). We show that activation of this pathway is caused by the autocrine or paracrine activation of the IGF1 receptor (IGF1R), as siRNA-mediated knockdown of the IGF1R effectively blocked exendin-4-stimulated PKB and mTORC1 activation. In contrast, pharmacological inactivation of the epidermal growth factor receptor has no discernible effect on exendin-4-stimulated PKB or mTORC1 activation. Therefore, we conclude that GLP1R agonists stimulate β-cell proliferation via the PKB-dependent stimulation of mTORC1/S6K1 whose activation is mediated through the autocrine aracrine activation of the IGF1R. This work provides a better understanding of the molecular basis of GLP1 agonist-induced β-cell proliferation which could potentially be exploited in the identification of novel drug targets that increase β-cell mass.
Publisher: Portland Press Ltd.
Date: 24-05-2018
DOI: 10.1042/BCJ20180130
Abstract: The target of rapamycin (TOR) is a protein kinase that, by forming complexes with partner proteins, governs erse cellular signalling networks to regulate a wide range of processes. TOR thus plays central roles in maintaining normal cellular functions and, when dysregulated, in erse diseases. TOR forms two distinct types of multiprotein complexes (TOR complexes 1 and 2, TORC1 and TORC2). TORC1 and TORC2 differ in their composition, their control and their substrates, so that they play quite distinct roles in cellular physiology. Much effort has been focused on deciphering the detailed regulatory links within the TOR pathways and the structure and control of TOR complexes. In this review, we summarize recent advances in understanding mammalian (m) TORC2, its structure, its regulation, and its substrates, which link TORC2 signalling to the control of cell functions. It is now clear that TORC2 regulates several aspects of cell metabolism, including lipogenesis and glucose transport. It also regulates gene transcription, the cytoskeleton, and the activity of a subset of other protein kinases.
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.EJMECH.2018.10.070
Abstract: The mitogen-activated protein kinase-interacting kinases 1 and 2 (MNK1 and MNK2) phosphorylate eukaryotic initiation factor 4E (eIF4E) and play important roles in promoting tumorigenesis and metabolic disease. Thus, inhibiting these enzymes might be valuable in the treatment of such conditions. We designed and synthesized a series of 4-((4-fluoro-2-isopropoxyphenyl)amino)-5-methylthieno[2,3-d]pyrimidine derivatives, and evaluated their inhibitory activity against the MNKs. We found 15 compounds that were active as MNK inhibitors and that one in particular, designated MNK-7g, which was potent against MNK1 and substantially more potent against MNK2. The compound MNK-7g did not affect other signaling pathways tested and had no adverse effects on cell viability. As expected from earlier studies, MNK-7g also inhibited cell migration. Therefore, the compound MNK-7g, which forms an ionic bond with Asp226 in MNK2 and possesses a substituted aniline in a thieno[2,3-d] pyrimidine structure, is a promising starting point for the future development of novel drugs for treating or managing cancer and metabolic disease.
Publisher: Elsevier BV
Date: 12-2011
Publisher: Informa UK Limited
Date: 24-01-2019
DOI: 10.1080/14728222.2019.1571043
Abstract: The mitogen-activated protein kinase (MAPK)-interacting kinases (MNKs) are switched on by the oncogenic MAPK (ERK) signalling pathway. They phosphorylate eukaryotic initiation factor (eIF) 4E, a protein which recruits ribosomes to mRNAs and thereby mediates their translation. Importantly, overexpression of eIF4E can transform cells, and its function is controlled by a second oncogenic pathway, mechanistic target of rapamycin complex 1. Areas covered: We have evaluated the literature related to the role of the MNKs in human cancers, including their control by oncogenic signalling pathways their expression and regulation in cancer cells and preclinical cancer models and their roles in the proliferation, survival and migration/invasion of cancer cells. We also discuss progress towards generating specific and potent inhibitors of the MNKs and data obtained using such compounds. Expert opinion: The available data indicate that MNKs and/or eIF4E phosphorylation play a role in oncogenic transformation, the progression of at least some tumours and especially in processes related to tumour metastasis. MNKs are clearly druggable targets and, as they are not essential, significant 'side effects' of inhibiting the MNKs are likely to be limited. Further work is required to assess the efficacy of MNK inhibition in tackling tumour development, progression and metastasis.
Publisher: Impact Journals, LLC
Date: 08-2016
Publisher: Portland Press Ltd.
Date: 26-11-2020
DOI: 10.1042/BCJ20200697
Abstract: Emerging advances in cancer therapy have transformed the landscape towards cancer immunotherapy regimens. Recent discoveries have resulted in the development of clinical immune checkpoint inhibitors that are ‘game-changers’ for cancer immunotherapy. Here we show that eEF2K, an atypical protein kinase that negatively modulates the elongation stage of protein synthesis, promotes the synthesis of PD-L1, an immune checkpoint protein which helps cancer cells to escape from immunosurveillance. Ablation of eEF2K in prostate and lung cancer cells markedly reduced the expression levels of the PD-L1 protein. We show that eEF2K promotes the association of PD-L1 mRNAs with translationally active polyribosomes and that translation of the PD-L1 mRNA is regulated by a uORF (upstream open reading-frame) within its 5′-UTR (5′-untranslated region) which starts with a non-canonical CUG as the initiation codon. This inhibitory effect is attenuated by eEF2K thereby allowing higher levels of translation of the PD-L1 coding region and enhanced expression of the PD-L1 protein. Moreover, eEF2K-depleted cancer cells are more vulnerable to immune attack by natural killer cells. Therefore, control of translation elongation can modulate the translation of this specific mRNA, one which contains an uORF that starts with CUG, and perhaps others that contain a similar feature. Taken together, our data reveal that eEF2K regulates PD-L1 expression at the level of the translation of its mRNA by virtue of a uORF in its 5′-region. This, and other roles of eEF2K in cancer cell biology (e.g. in cell survival and migration), may be exploited for the design of future therapeutic strategies.
Publisher: Elsevier BV
Date: 07-2020
Publisher: MDPI AG
Date: 29-06-2021
Abstract: Breast and prostate cancer are the second and third leading causes of death amongst all cancer types, respectively. Pathogenesis of these malignancies is characterised by dysregulation of sex hormone signalling pathways, mediated by the estrogen receptor-α (ER) in breast cancer and androgen receptor (AR) in prostate cancer. ER and AR are transcription factors whose aberrant function drives oncogenic transcriptional programs to promote cancer growth and progression. While ER/AR are known to stimulate cell growth and survival by modulating gene transcription, emerging findings indicate that their effects in neoplasia are also mediated by dysregulation of protein synthesis (i.e., mRNA translation). This suggests that ER/AR can coordinately perturb both transcriptional and translational programs, resulting in the establishment of proteomes that promote malignancy. In this review, we will discuss relatively understudied aspects of ER and AR activity in regulating protein synthesis as well as the potential of targeting mRNA translation in breast and prostate cancer.
Publisher: Informa UK Limited
Date: 2014
DOI: 10.4161/TRLA.28174
Publisher: Springer Science and Business Media LLC
Date: 13-03-2020
Publisher: Cold Spring Harbor Laboratory
Date: 09-2020
DOI: 10.1101/2020.09.01.278655
Abstract: Emerging advances in cancer therapy have transformed the landscape from conventional therapies towards cancer immunotherapy regimens. Recent discoveries have resulted in the development of clinical immune checkpoint inhibitors that are ‘game-changers’ for cancer immunotherapy. Here we show that eEF2K, an atypical protein kinase that inhibits the elongation stage of protein synthesis, actually promotes the synthesis of PD-L1, an immune checkpoint protein which helps cancer cells to escape from immunosurveillance. Ablation of eEF2K in prostate and lung cancer cells markedly reduced the expression levels of the PD-L1 protein. We show that eEF2K promotes the association of PD-L1 mRNAs with translationally active polyribosomes and that translation of the PD-L1 mRNA is regulated by a uORF (upstream open reading-frame) within its 5’-UTR (5’-untranslated region) which starts with a non-canonical CUG codon. This inhibitory effect is attenuated by eEF2K thereby allowing higher levels of translation of the PD-L1 coding region and enhanced expression of the PD-L1 protein. Moreover, eEF2K-depleted cancer cells are more vulnerable to immune attack by natural killer cells. Therefore, control of translation elongation can modulate the translation of this specific mRNA, one which contains an uORF that starts with CUG, and perhaps others that contain a similar feature. Taken together, our data reveal that eEF2K regulates PD-L1 expression at the level of the translation of its mRNA by virtue of a uORF in its 5’-region. This, and other roles of eEF2K in cancer cell biology (e.g., in cell survival and migration), may be exploited for the design of future therapeutic strategies.
Publisher: Springer Science and Business Media LLC
Date: 09-11-2011
DOI: 10.1007/S00018-011-0874-4
Abstract: Type-2 diabetes mellitus (T2DM) is a disorder that is characterized by high blood glucose concentration in the context of insulin resistance and/or relative insulin deficiency. It causes metabolic changes that lead to the damage and functional impairment of organs and tissues resulting in increased morbidity and mortality. It is this form of diabetes whose prevalence is increasing at an alarming rate due to the 'obesity epidemic', as obesity is a key risk factor in the development of insulin resistance. However, the majority of in iduals who have insulin resistance do not develop diabetes due to a compensatory increase in insulin secretion in response to an increase in insulin demand. This adaptive response is sustained by an increase in both β-cell function and mass. Importantly, there is increasing evidence that the Serine/Threonine kinase mammalian target of rapamycin (mTOR) plays a key role in the regulation of β-cell mass and therefore likely plays a critical role in β-cell adaptation. Therefore, the primary focus of this review is to summarize our current understanding of the role of mTOR in stimulating pancreatic β-cell mass and thus, in the prevention of type-2 diabetes.
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jianling Xie.