scholarly journals Dock/Nck facilitates PTP61F/PTP1B regulation of insulin signalling

2011 ◽  
Vol 439 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Chia-Lun Wu ◽  
Bree Buszard ◽  
Chun-Hung Teng ◽  
Wei-Lin Chen ◽  
Coral G. Warr ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Insulin Signalling ◽  
Tyrosine Phosphatase ◽  
Adaptor Protein ◽  
Receptor Activation ◽  
Negative Regulator ◽  
Stable Complex

PTP1B (protein tyrosine phosphatase 1B) is a negative regulator of IR (insulin receptor) activation and glucose homoeostasis, but the precise molecular mechanisms governing PTP1B substrate selectivity and the regulation of insulin signalling remain unclear. In the present study we have taken advantage of Drosophila as a model organism to establish the role of the SH3 (Src homology 3)/SH2 adaptor protein Dock (Dreadlocks) and its mammalian counterpart Nck in IR regulation by PTPs. We demonstrate that the PTP1B orthologue PTP61F dephosphorylates the Drosophila IR in S2 cells in vitro and attenuates IR-induced eye overgrowth in vivo. Our studies indicate that Dock forms a stable complex with PTP61F and that Dock/PTP61F associate with the IR in response to insulin. We report that Dock is required for effective IR dephosphorylation and inactivation by PTP61F in vitro and in vivo. Furthermore, we demonstrate that Nck interacts with PTP1B and that the Nck/PTP1B complex inducibly associates with the IR for the attenuation of IR activation in mammalian cells. Our studies reveal for the first time that the adaptor protein Dock/Nck attenuates insulin signalling by recruiting PTP61F/PTP1B to its substrate, the IR.

scholarly journals HIVEP1 Is a Negative Regulator of NF-κB That Inhibits Systemic Inflammation in Sepsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Hisatake Matsumoto ◽  
Brendon P. Scicluna ◽  
Kin Ki Jim ◽  
Fahimeh Falahi ◽  
Wanhai Qin ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Negative Regulator ◽  
Type I ◽  
Promoter Regions ◽  
Monocytic Cells ◽  
Site Analysis ◽  
Enhancer Binding Protein ◽  
Transcriptomic Changes

Our previous work identified human immunodeficiency virus type I enhancer binding protein 1 (HIVEP1) as a putative driver of LPS-induced NF-κB signaling in humans in vivo. While HIVEP1 is known to interact with NF-ĸB binding DNA motifs, its function in mammalian cells is unknown. We report increased HIVEP1 mRNA expression in monocytes from patients with sepsis and monocytes stimulated by Toll-like receptor agonists and bacteria. In complementary overexpression and gene deletion experiments HIVEP1 was shown to inhibit NF-ĸB activity and induction of NF-ĸB responsive genes. RNA sequencing demonstrated profound transcriptomic changes in HIVEP1 deficient monocytic cells and transcription factor binding site analysis showed enrichment for κB site regions. HIVEP1 bound to the promoter regions of NF-ĸB responsive genes. Inhibition of cytokine production by HIVEP1 was confirmed in LPS-stimulated murine Hivep1-/- macrophages and HIVEP1 knockdown zebrafish exposed to the common sepsis pathogen Streptococcus pneumoniae. These results identify HIVEP1 as a negative regulator of NF-κB in monocytes/macrophages that inhibits proinflammatory reactions in response to bacterial agonists in vitro and in vivo.

scholarly journals Histone methyltransferase SET8 is regulated by miR-192/215 and induces oncogene-induced senescence via p53-dependent DNA damage in human gastric carcinoma cells

2020 ◽  
Vol 11 (10) ◽  
Author(s):  
Xiaojing Zhang ◽  
Yin Peng ◽  
Yuan Yuan ◽  
Yuli Gao ◽  
Fan Hu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Molecular Mechanisms ◽  
Biological Activities ◽  
Expression Profiles ◽  
Carcinoma Cells ◽  
Negative Regulator ◽  
Expression Change ◽  
Human Gastric Carcinoma Cells

Abstract Gastric cancer (GC) is the most common cancer throughout the world. Despite advances of the treatments, detailed oncogenic mechanisms are largely unknown. In our previous study, we investigated microRNA (miR) expression profiles in human GC using miR microarrays. We found miR-192/215 were upregulated in GC tissues. Then gene microarray was implemented to discover the targets of miR-192/215. We compared the expression profile of BGC823 cells transfected with miR-192/215 inhibitors, and HFE145 cells transfected with miR-192/-215 mimics, respectively. SET8 was identified as a proposed target based on the expression change of more than twofold. SET8 belongs to the SET domain-containing methyltransferase family and specifically catalyzes monomethylation of H4K20me. It is involved in diverse functions in tumorigenesis and metastasis. Therefore, we focused on the contributions of miR-192/215/SET8 axis to the development of GC. In this study, we observe that functionally, SET8 regulated by miR-192/215 is involved in GC-related biological activities. SET8 is also found to trigger oncogene-induced senescence (OIS) in GC in vivo and in vitro, which is dependent on the DDR (DNA damage response) and p53. Our findings reveal that SET8 functions as a negative regulator of metastasis via the OIS-signaling pathway. Taken together, we investigated the functional significance, molecular mechanisms, and clinical impact of miR-192/215/SET8/p53 in GC.

scholarly journals CEACAM1 negatively regulates platelet-collagen interactions and thrombus growth in vitro and in vivo

Blood ◽  
2009 ◽  
Vol 113 (8) ◽  
pp. 1818-1828 ◽  
Author(s):  
Cyndi Wong ◽  
Yong Liu ◽  
Jana Yip ◽  
Rochna Chand ◽  
Janet L. Wee ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Tyrosine Phosphatase ◽  
Negative Regulator ◽  
Surface Glycoprotein ◽  
Type I ◽  
Wild Type ◽  
Glycoprotein Vi ◽  
Selective Ligand

Abstract Carcinoembryonic antigen cell adhesion molecule-1 (CEACAM1) is a surface glycoprotein expressed on various blood cells, epithelial cells, and vascular cells. CEACAM1 possesses adhesive and signaling properties mediated by its intrinsic immunoreceptor tyrosine-based inhibitory motifs that recruit SHP-1 protein-tyrosine phosphatase. In this study, we demonstrate that CEACAM1 is expressed on the surface and in intracellular pools of platelets. In addition, CEACAM1 serves to negatively regulate signaling of platelets by collagen through the glycoprotein VI (GPVI)/Fc receptor (FcR)–γ-chain. ceacam1−/− platelets displayed enhanced type I collagen and GPVI-selective ligand, collagen-related peptide (CRP), CRP-mediated platelet aggregation, enhanced platelet adhesion on type I collagen, and elevated CRP-mediated alpha and dense granule secretion. Platelets derived from ceacam1−/− mice form larger thrombi when perfused over a collagen matrix under arterial flow compared with wild-type mice. Furthermore, using intravital microscopy to ferric chloride-injured mesenteric arterioles, we show that thrombi formed in vivo in ceacam1−/− mice were larger and were more stable than those in wild-type mice. GPVI depletion using monoclonal antibody JAQ1 treatment of ceacam1−/− mice showed a reversal in the more stable thrombus growth phenotype. ceacam1−/− mice were more susceptible to type I collagen–induced pulmonary thromboembolism than wild-type mice. Thus, CEACAM1 acts as a negative regulator of platelet-collagen interactions and of thrombus growth involving the collagen GPVI receptor in vitro and in vivo.

scholarly journals TRIB1 regulates tumour growth via controlling tumour-associated macrophage phenotypes and is associated with breast cancer survival and treatment response

2021 ◽  
Author(s):  
Taewoo Kim ◽  
Jessica Johnston ◽  
Francisco J. C. Felipe ◽  
Stephen Hamby ◽  
Sonia Castillo-Lluva ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Tumour Growth ◽  
Molecular Mechanisms ◽  
Cancer Survival ◽  
Selective Reduction ◽  
Tumour Volume ◽  
Negative Regulator ◽  
Response To Chemotherapy

Molecular mechanisms that regulate tumour-associated macrophage (TAM) phenotype and function are incompletely understood. Here, we show that the pseudokinase TRIB1 is highly expressed by TAMs in breast cancer and that its expression correlates with response to chemotherapy and patient survival. We used immune-competent murine models of breast cancer to characterise the consequences of altered (reduced or elevated) myeloid Trib1 expression on tumour growth and composition of stromal immune cells. We found that both overexpression and knockout of myeloid Trib1 promote tumour growth, albeit through distinct molecular mechanisms. Myeloid Trib1 deficiency resulted in an early accelearation of tumour growth, paired with a selective reduction in perivascular macrophage numbers in vivo and enhanced oncogenic cytokine expression in vitro. In contrast, elevated levels of Trib1 in myeloid cells led to an increase in mammary tumour volume at late stages, together with a reduction of NOS2 expressing macrophages and an overall reduction of these cells in hypoxic tumour regions. In addition, we show that myeloid Trib1 is a previously unknown, negative regulator of the anti-tumour cytokine IL-15 and that increased expression of myeloid Trib1 leads to reduced IL-15 levels in mammary tumours, with a consequent reduction in the number of T-cells, that are key to anti-tumour immune responses. Together, these results define the different roles of TRIB1 in human breast cancer and provide a mechanistic understanding for the importance of myeloid TRIB1 expression levels in the development of this disease.

scholarly journals The LbcA lipoprotein and CtpA protease assemble an oligomeric complex to control peptidoglycan hydrolases in Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Huilin Li ◽  
Hao-Chi Hsu ◽  
Michelle Wang ◽  
Amanda Kovach ◽  
Andrew J Darwin
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Molecular Mechanisms ◽  
Adaptor Protein ◽  
Activation Mechanism ◽  
Peptidoglycan Hydrolase ◽  
Tetratricopeptide Repeats ◽  
Active Protease ◽  
Processing Protease

Pseudomonas aeruginosa CtpA is a carboxyl terminal–processing protease that partners with the outer membrane lipoprotein LbcA to degrade cell wall cross-link hydrolases. This activity plays an important role in supporting P. aeruginosa virulence. However, almost nothing is known about the molecular mechanisms underlying CtpA and LbcA function. Here, we used structural analysis to show that CtpA alone assembles into an inactive hexamer comprising a trimer of dimers, which limits its substrate access and prevents nonspecific degradation. The adaptor protein LbcA is a right-handed open spiral with 11 tetratricopeptide repeats, which might wrap around a substrate to deliver it to CtpA for degradation. We found that up to three LbcA molecules can bind to one CtpA hexamer to assemble a giant, active protease complex that degrades its peptidoglycan hydrolase substrates both in vitro and in vivo. This work reveals an intricate protease activation mechanism that is substrate delivery-dependent and enables targeted removal of the peptidoglycan hydrolase substrates.

scholarly journals Adaptor protein LNK promotes anaplastic thyroid carcinoma cell growth via 14-3-3 ε/γ binding

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhao-Ming Zhong ◽  
Xue Chen ◽  
Xiao Qi ◽  
Xue-Min Wang ◽  
Chun-Yan Li ◽  
...  
Keyword(s):  
Thyroid Carcinoma ◽  
Molecular Mechanisms ◽  
Adaptor Protein ◽  
Anaplastic Thyroid Carcinoma ◽  
Negative Regulator ◽  
In Vitro Assays ◽  
Rapid Progression ◽  
Thyroid Cells ◽  
Normal Thyroid

Abstract Background Rapid progression contributes to treatment failure in anaplastic thyroid carcinoma (ATC) patients. In a preliminary study, we demonstrated that some hematopoietic factors may be involved in the progression of ATC. The adaptor protein LNK, which is a negative regulator of hematopoietic cytokine signalling, has been studied extensively in malignant hematopoietic cells. However, there are few studies on LNK in solid tumours. Methods Real-time PCR, immunohistochemistry (IHC) and western blot analysis of LNK were performed on ATC cells, differentiated thyroid cancer (DTC) cells and normal thyroid cells. In vitro assays (including pull-down, liquid chromatography-mass spectrometry (LC–MS), co-IP, MTT and colony formation) were performed to validate the effect of LNK on ATC progression and elucidate the molecular mechanisms. Results Compared with DTC cells and normal thyroid cells, ATC cells exhibit overexpression of LNK. In addition, LNK overexpression results in increased proliferation of ATC cells. Conversely, LNK knockdown significantly suppresses ATC cell proliferation. LC–MS identified the 14-3-3 ε/γ protein as a LNK binding partner. Finally, the results indicate that LNK overexpression significantly enhances the anti-apoptotic ability of ATC cells via the Akt-NFκB-Bcl-2/Bcl-xL pathway and that the oncogenic effect of LNK largely depends on 14-3-3 ε/γ binding. Conclusions The present study elucidated the important role of LNK in the growth of ATC opposite to its behaviour in the hematopoietic system and indicates that LNK is a potential target for the treatment of ATC.

scholarly journals The E3 Ubiquitin Ligase TBK1 Mediates the Degradation of Multiple Picornavirus VP3 Proteins by Phosphorylation and Ubiquitination

2019 ◽  
Vol 93 (23) ◽  
Author(s):  
Dan Li ◽  
Wenping Yang ◽  
Jingjing Ren ◽  
Yi Ru ◽  
Keshan Zhang ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
E3 Ubiquitin Ligase ◽  
Adaptor Protein ◽  
Ubiquitin Ligase Activity ◽  
Lysine Residues ◽  
Innate Antiviral Immunity

ABSTRACT TANK-binding kinase 1 (TBK1) is essential for interferon beta (IFN-β) production and innate antiviral immunity. However, other, additional functions of TBK1 have remained elusive. Here, we showed that TBK1 is an E3 ubiquitin ligase that undergoes self-ubiquitylation in vitro in the presence of the E2 enzyme UbcH5c. Further evidence showed that TBK1 could also be self-ubiquitylated in vivo. Importantly, multiple picornavirus VP3 proteins were degraded by TBK1 through its kinase and E3 ubiquitin ligase activity. Mechanistically, TBK1 phosphorylated multiple picornavirus VP3 proteins at serine residues and ubiquitinated them via K63-linked ubiquitination at lysine residues. In addition, the C426 and C605 residues of TBK1 were not essential for TBK1 innate immunity activity; however, these residues were required for degradation of multiple picornavirus VP3 proteins and for its E3 ubiquitin ligase activity. Hence, our findings identified a novel role of TBK1 in regulating the virus life cycle and provided new insights into the molecular mechanisms of TBK1-mediated antiviral response. IMPORTANCE TBK1 is an important adaptor protein required for innate immune response to viruses, but its other functions were unknown. In this study, we found that TBK1 is an E3 ubiquitin ligase that undergoes self-ubiquitylation in vitro in the presence of the E2 enzyme UbcH5c. In addition, multiple picornavirus VP3 proteins were degraded by TBK1 through its kinase and E3 ubiquitin ligase activity. Our report provides evidence that TBK1 plays a role in viral protein degradation.

scholarly journals HDAC3 maintains oocyte meiosis arrest by repressing amphiregulin expression before the LH surge

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Huarong Wang ◽  
Han Cai ◽  
Xiao Wang ◽  
Meiling Zhang ◽  
Bingying Liu ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Granulosa Cells ◽  
Molecular Mechanisms ◽  
Conditional Knockout ◽  
Negative Regulator ◽  
Lh Surge ◽  
Oocyte Meiosis ◽  
H3k14 Acetylation

AbstractIt is known that granulosa cells (GCs) mediate gonadotropin-induced oocyte meiosis resumption by releasing EGF-like factors in mammals, however, the detailed molecular mechanisms remain unclear. Here, we demonstrate that luteinizing hormone (LH) surge-induced histone deacetylase 3 (HDAC3) downregulation in GCs is essential for oocyte maturation. Before the LH surge, HDAC3 is highly expressed in GCs. Transcription factors, such as FOXO1, mediate recruitment of HDAC3 to the amphiregulin (Areg) promoter, which suppresses AREG expression. With the LH surge, decreased HDAC3 in GCs enables histone H3K14 acetylation and binding of the SP1 transcription factor to the Areg promoter to initiate AREG transcription and oocyte maturation. Conditional knockout of Hdac3 in granulosa cells in vivo or inhibition of HDAC3 activity in vitro promotes the maturation of oocytes independent of LH. Taking together, HDAC3 in GCs within ovarian follicles acts as a negative regulator of EGF-like growth factor expression before the LH surge.

Phosphatase Wip1 negatively regulates neutrophil development through p38 MAPK-STAT1

Blood ◽  
2013 ◽  
Vol 121 (3) ◽  
pp. 519-529 ◽  
Author(s):  
Guangwei Liu ◽  
Xuelian Hu ◽  
Bo Sun ◽  
Tao Yang ◽  
Jianfeng Shi ◽  
...  
Keyword(s):  
P38 Mapk ◽  
Molecular Mechanisms ◽  
Negative Regulator ◽  
Cell Type ◽  
A Cell ◽  
Cell Type Specific ◽  
Neutrophil Differentiation ◽  
Deficient Mice

Abstract Neutrophils are critically involved in host defense and tissue damage. Intrinsic molecular mechanisms controlling neutrophil differentiation and activities are poorly defined. Herein we found that p53-induced phosphatase 1(Wip1) is preferentially expressed in neutrophils among immune cells. The Wip1 expression is gradually up-regulated during the differentiation of myeloid precursors into mature neutrophils. Wip1-deficient mice and chimera mice with Wip1−/− hematopoietic cells had an expanded pool of neutrophils with hypermature phenotypes in the periphery. The in vivo and in vitro studies showed that Wip1 deficiency mainly impaired the developing process of myeloid progenitors to neutrophils in an intrinsic manner. Mechanism studies showed that the enhanced development and maturation of neutrophils caused by Wip1 deficiency were mediated by p38 MAPK-STAT1 but not p53-dependent pathways. Thus, our findings identify a previously unrecognized p53-independent function of Wip1 as a cell type-specific negative regulator of neutrophil generation and homeostasis through limiting the p38 MAPK-STAT1 pathway.

scholarly journals Ncx3-Induced Mitochondrial Dysfunction in Midbrain Leads to Neuroinflammation in Striatum of A53t-α-Synuclein Transgenic Old Mice

2021 ◽  
Vol 22 (15) ◽  
pp. 8177
Author(s):  
Rossana Di Martino ◽  
Maria Josè Sisalli ◽  
Rossana Sirabella ◽  
Salvatore Della Notte ◽  
Domenica Borzacchiello ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Fluorescent Dyes ◽  
Neuronal Loss ◽  
Calcium Content ◽  
Alpha Synuclein ◽  
Dopaminergic Neurodegeneration

The exact mechanism underlying selective dopaminergic neurodegeneration is not completely understood. The complex interplay among toxic alpha-synuclein aggregates, oxidative stress, altered intracellular Ca2+-homeostasis, mitochondrial dysfunction and disruption of mitochondrial integrity is considered among the pathogenic mechanisms leading to dopaminergic neuronal loss. We herein investigated the molecular mechanisms leading to mitochondrial dysfunction and its relationship with activation of the neuroinflammatory process occurring in Parkinson’s disease. To address these issues, experiments were performed in vitro and in vivo in mice carrying the human mutation of α-synuclein A53T under the prion murine promoter. In these models, the expression and activity of NCX isoforms, a family of important transporters regulating ionic homeostasis in mammalian cells working in a bidirectional way, were evaluated in neurons and glial cells. Mitochondrial function was monitored with confocal microscopy and fluorescent dyes to measure mitochondrial calcium content and mitochondrial membrane potential. Parallel experiments were performed in 4 and 16-month-old A53T-α-synuclein Tg mice to correlate the functional data obtained in vitro with mitochondrial dysfunction and neuroinflammation through biochemical analysis. The results obtained demonstrated: 1. in A53T mice mitochondrial dysfunction occurs early in midbrain and later in striatum; 2. mitochondrial dysfunction occurring in the midbrain is mediated by the impairment of NCX3 protein expression in neurons and astrocytes; 3. mitochondrial dysfunction occurring early in midbrain triggers neuroinflammation later into the striatum, thus contributing to PD progression during mice aging.

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