3011 total record number
25 records this year

To narrow your search, use one or more of the following search menus below.

To search by keyword, you may search by type of cell/animal/assay/protein/research or publication.

Items 2936 to 2940 of 3009 total

per page
  • High-resolution crystal structure of human asparagine synthetase enables analysis of inhibitor binding and selectivity

    Zhu, W; Radadiya, A; Bisson, C; Wenzel, S; Nordin, BE; Martínez-Márquez, F; Imasaki, T; Sedelnikova, SE; Coricello, A; Baumann, P; Berry, AH; Nomanbhoy, TK; Kozarich, JW; Jin, Y; Rice, DW; Takagi, Y; Richards, NGJ
    1School of Chemistry, Cardiff University, Cardiff, UK
    Expression of human asparagine synthetase (ASNS) promotes metastatic progression and tumor cell invasiveness in colorectal and breast cancer, presumably by altering cellular levels of L-asparagine. Human ASNS is therefore emerging as a bona fide drug target for cancer therapy. Here we show that a slow-onset, tight binding inhibitor, which exhibits nanomolar affinity for human ASNS in vitro, exhibits excellent selectivity at 10 μM concentration in HCT-116 cell lysates with almost no off-target binding. The high-resolution (1.85 Å) crystal structure of human ASNS has enabled us to identify a cluster of negatively charged side chains in the synthetase domain that plays a key role in inhibitor binding. Comparing this structure with those of evolutionarily related AMP-forming enzymes provides insights into intermolecular interactions that give rise to the observed binding selectivity. Our findings demonstrate the feasibility of developing second generation human ASNS inhibitors as lead compounds for the discovery of drugs against metastasis.
  • Mechanism of manganese dysregulation of dopamine neuronal activity

    Lin, M; Colon-Perez, LM; Sambo, DO; Miller, DR;
    Department of Neuroscience, University of Florida, Gainesville, FL 32611
    Manganese exposure produces Parkinson’s-like neurological symptoms, suggesting a selective dysregulation of dopamine transmission. It is unknown, however, how manganese accumulates in dopaminergic brain regions or how it regulates the activity of dopamine neurons. Our in vivo studies suggest manganese accumulates in dopamine neurons of the ventral tegmental area and substantia nigra via nifedipine-sensitive Ca2+ channels. Manganese produces a Ca2+ channel-mediated current which increases neurotransmitter release and rhythmic firing activity of dopamine neurons. These increases are prevented by blockade of Ca2+ channels and depend on downstream recruitment of Ca2+-activated potassium channels to the plasma membrane. These findings demonstrate the mechanism of manganese-induced dysfunction of dopamine neurons, and reveal a potential therapeutic target to attenuate manganese-induced impairment of dopamine transmission.
  • The mood stabilizer lithium slows down synaptic vesicle cycling at glutamatergic synapses

    Tang, W; Cory, B; Lim, KL; Fivaz, M;
    National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433
    Product(s): Bafilomycin A1
    Lithium is a mood stabilizer broadly used to prevent and treat symptoms of mania and depression in people with bipolar disorder (BD). Little is known, however, about its mode of action. Here, we analyzed the impact of lithium on synaptic vesicle (SV) cycling at presynaptic terminals releasing glutamate, a neurotransmitter previously implicated in BD and other neuropsychiatric conditions. We used the pHluorin-based synaptic tracer vGpH and a fully automated image processing pipeline to quantify the effect of lithium on both SV exocytosis and endocytosis in hippocampal neurons. We found that lithium selectively reduces SV exocytic rates during electrical stimulation, and markedly slows down SV recycling post-stimulation. Analysis of single bouton responses revealed the existence of functionally distinct excitatory synapses with varying sensitivity to lithium ― some terminals show responses similar to untreated cells, while others are markedly impaired in their ability to recycle SVs. While the cause of this heterogeneity is unclear, these data indicate that lithium interacts with the SV machinery and influences glutamate release in a large fraction of excitatory synapses. Together, our findings show that lithium down modulates SV cycling, an effect consistent with clinical reports indicating hyperactivation of glutamate neurotransmission in BD.
  • Decreased K13 Abundance Reduces Hemoglobin Catabolism and Proteotoxic Stress, Underpinning Artemisinin Resistance

    Yang, T; Yeoh, LM; Tutor, MV; Dixon, MW; McMillan, PJ; Xie, SC; Bridgford, JL; Gillett, DL; Duffy, MF; Ralph, SA; McConville, MJ; Tilley, L; Cobbold, SA;
    Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC 3010, Australia
    Increased tolerance of Plasmodium falciparum to front-line artemisinin antimalarials (ARTs) is associated with mutations in Kelch13 (K13), although the precise role of K13 remains unclear. Here, we show that K13 mutations result in decreased expression of this protein, while mislocalization of K13 mimics resistance-conferring mutations, pinpointing partial loss of function of K13 as the relevant molecular event. K13-GFP is associated with ∼170 nm diameter doughnut-shaped structures at the parasite periphery, consistent with the location and dimensions of cytostomes. Moreover, the hemoglobin-peptide profile of ring-stage parasites is reduced when K13 is mislocalized. We developed a pulse-SILAC approach to quantify protein turnover and observe less disruption to protein turnover following ART exposure when K13 is mislocalized. Our findings suggest that K13 regulates digestive vacuole biogenesis and the uptake/degradation of hemoglobin and that ART resistance is mediated by a decrease in heme-dependent drug activation, less proteotoxicity, and increased survival of parasite ring stages. Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.
  • The deubiquitinating enzyme PSMD14 facilitates tumor growth and chemoresistance through stabilizing the ALK2 receptor in the initiation of BMP6 signaling pathway

    Seo, D; Jung, SM; Park, JS; Lee, J; Ha, J; Kim, M; Park, SH;
    Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
    Product(s): MG-132
    Although bone morphogenetic protein 6 (BMP6) signaling pathway has been implicated in many types of cancer, its role of tumorigenesis seems to be controversial and its ubiquitin-modifying mechanisms have not been fully addressed. Our study was designed to investigate how BMP6 signaling pathway is regulated by ubiquitin-modifying systems and to address molecular and clinical significance in colorectal cancers. Human deubiquitnase (DUB) siRNA library was used to screen the specific DUB, named PSMD14, involved in BMP6 signaling pathway. Immunoblot, immunoprecipitation and ubiquitination assays were used to analyze targets of the PSMD14. A role of PSMD14-mediated BMP6 signaling pathway for malignant cancer progression was investigated using in vitro and in vivo model of colorectal cancers as well as clinical samples of colorectal cancer patients. The deubiquitinase PSMD14 acts as a positive regulator for the initiation of the BMP6 signaling pathway through deubiquitinating K48-linked ALK2 type I receptor ubiquitination mediated by Smurf1 E3 ligase, resulting in increased stability of the ALK2. This role of PSMD14 is independent of its intrinsic role in the 26S proteasome system. Furthermore, either PSMD14 or ALK2 depletion significantly decreases tumorigenesis of HCT116 colorectal cancer cells in a xenograft model as well as cancer stemness/chemoresistance, and expression of the PSMD14 and ALK2 gene are correlated with malignant progression and the survival of colorectal cancer patients. These findings suggest that the PSMD14-ALK2 axis plays an essential role in initiation of the BMP6 signaling pathway and contributes to tumorigenesis and chemoresistance of colorectal cancers. Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.

Items 2936 to 2940 of 3009 total

per page
To Top