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Mark Hedglin, Binod Pandey, Stephen J Benkovic
Translesion DNA synthesis (TLS) during S-phase uses specialized TLS DNA polymerases to replicate a DNA lesion, allowing stringent DNA synthesis to resume beyond the offending damage. Human TLS involves the conjugation of ubiquitin to PCNA clamps encircling damaged DNA and the role of this post-translational modification is under scrutiny. A widely-accepted model purports that ubiquitinated PCNA recruits TLS polymerases such as pol η to sites of DNA damage where they may also displace a blocked replicative polymerase...
October 22, 2016: ELife
Akhi Akhter, Emanuel Rosonina
The Saccharomyces cerevisiae transcription factor Gcn4 is expressed during amino acid starvation and its abundance is controlled by ubiquitin-mediated proteolysis. Cdk8, a kinase component of the RNA polymerase II Mediator complex, phosphorylates Gcn4 which triggers its ubiquitination/proteolysis and is thought to link Gcn4 degradation with transcription of target genes. In addition to phosphorylation and ubiquitination, we previously showed that Gcn4 becomes sumoylated in a DNA-binding dependent manner, while a non-sumoylatable form of Gcn4 showed increased chromatin occupancy, but only if Cdk8 was present...
October 21, 2016: Genetics
Liqing Wang, Suresh Kumar, Satinder Dahiya, Feng Wang, Jian Wu, Kheng Newick, Rongxiang Han, Arabinda Samanta, Ulf H Beier, Tatiana Akimova, Tricia R Bhatti, Benjamin Nicholson, Mathew P Kodrasov, Saket Agarwal, David E Sterner, Wei Gu, Joseph Weinstock, Tauseef R Butt, Steven M Albelda, Wayne W Hancock
Foxp3+ T-regulatory (Treg) cells are known to suppress protective host immune responses to a wide variety of solid tumors, but their therapeutic targeting is largely restricted to their transient depletion or "secondary" modulation, e.g. using anti-CTLA-4 monoclonal antibody. Our ongoing studies of the post-translational modifications that regulate Foxp3 demonstrated that the histone/protein acetyltransferase, Tip60, plays a dominant role in promoting acetylation, dimerization and function in Treg cells. We now show that the ubiquitin-specific protease, Usp7, controls Treg function largely by stabilizing the expression and promoting the multimerization of Tip60 and Foxp3...
October 15, 2016: EBioMedicine
Srikanth Appikonda, Kaushik N Thakkar, Michelle Craig Barton
Tripartite Motif-containing protein 24 (TRIM24) functions as an E3 ligase targeting p53 for ubiquitination, a histone 'reader' that interacts with a specific signature of histone post-translational modifications and a co-regulator of nuclear receptor-regulated transcription. Although mouse models of Trim24 depletion suggest that TRIM24 may be a liver-specific tumor suppressor, several studies show that human TRIM24 is an oncogene when aberrantly over expressed. This review focuses on the mechanisms of TRIM24 functions in oncogenesis and metabolic reprogramming, which underlie recent interest in therapeutic targeting of aberrant TRIM24 in human cancers...
March 2016: Drug Discovery Today. Technologies
Cheng-Fu Chang, Yi-Chao Lee, Kuen-Haur Lee, Hui-Ching Lin, Chia-Ling Chen, Che-Kun James Shen, Chi-Chen Huang
BACKGROUND: In the central nervous system regions of the sporadic and familial FTLD and ALS patients, TDP-43 has been identified as the major component of UBIs inclusions which is abnormally hyperphosphorylated, ubiquitinated, and cleaved into C-terminal fragments to form detergent-insoluble aggregates. So far, the effective drugs for FTLD and ALS neurodegenerative diseases are yet to be developed. Autophagy has been demonstrated as the major metabolism route of the pathological TDP-43 inclusions, hence activation of autophagy is a potential therapeutic strategy for TDP-43 pathogenesis in FTLD and ALS...
October 21, 2016: Journal of Biomedical Science
Tadamoto Isogai, Rob van der Kammen, Onno B Bleijerveld, Soenita S Goerdayal, Elisabetta Argenzio, A F Maarten Altelaar, Metello Innocenti
Formin mDia2 is a cytoskeleton-regulatory protein that switches reversibly between a closed, auto-inhibited and an open, active conformation. Although the open conformation of mDia2 induces actin assembly thereby controlling many cellular processes, mDia2 possesses also actin-independent and conformation-insensitive scaffolding roles related to microtubules and p53, respectively. Thus, we hypothesise that mDia2 may have other unappreciated functions and regulatory modes. Here we identify and validate proteasome and Ubiquitin as mDia2-interacting partners using SILAC-based quantitative proteomics and biochemistry, respectively...
October 21, 2016: Journal of Proteome Research
Julia M Fraile, Diana Campos-Iglesias, Francisco Rodríguez, Yaiza Español, José M P Freije
Ubiquitin-Specific Proteases (USPs) are deubiquitinating enzymes frequently deregulated in human malignancies. Here, we show that USP54 is overexpressed in intestinal stem cells and demonstrate that its downregulation in colorectal carcinoma cells impedes tumorigenesis. We have generated mutant mice deficient for this deubiquitinase, which are viable and fertile, and protected against chemically-induced colorectal carcinoma. Furthermore, we show that USP54 is upregulated in human colon cancer and associates with poor prognosis...
October 19, 2016: Oncotarget
Laura de Diego-García, Mercedes Ramírez-Escudero, Álvaro Sebastián-Serrano, Juan Ignacio Diaz-Hernández, Jesús Pintor Just, José J Lucas, Miguel Díaz-Hernández
The Ubiquitin-Proteasome System (UPS) is essential for the regulation of the cellular proteostasis. Indeed, it has been postulated that an UPS dysregulation is the common mechanism that underlies several neurological disorders. Considering that extracellular nucleotides, through their selective P2Y2 receptor (P2Y2R), play a neuroprotective role in various neurological disorders that course with an UPS impairment, we wonder if this neuroprotective capacity resulted from their ability to modulate the UPS. Using a cellular model expressing two different UPS reporters, we found that the stimulation of P2Y2R by its selective agonist Up4U induced a significant reduction of UPS reporter levels...
October 18, 2016: Biochimica et Biophysica Acta
Heba M Ismail, Athanasios Didangelos, Tonia L Vincent, Jeremy Saklatvala
Objectives Mechanical injury to cartilage predisposes to osteoarthritis (OA). Wounding the articular cartilage surface causes rapid activation of MAP kinases and NFκB mimicking the response to inflammatory cytokines. Here, we identify the upstream signalling mechanisms involved. Methods Cartilage was injured by dissecting it from the articular surface of porcine metacarpophalangeal joints (MCP) or by avulsing murine proximal femoral epiphyses. Protein phosphorylation was assayed by Western blotting of cartilage lysates...
October 21, 2016: Arthritis & Rheumatology
Oznur Bayraktar, Ozlem Oral, Nur Mehpare Kocaturk, Yunus Akkoc, Karin Eberhart, Ali Kosar, Devrim Gozuacik
The ubiquitin-proteasome system (UPS) degrades soluble proteins and small aggregates, whereas macroautophagy (autophagy herein) eliminates larger protein aggregates, tangles and even whole organelles in a lysosome-dependent manner. VCP/p97 was implicated in both pathways. VCP/p97 mutations cause a rare multisystem disease called IBMPFD (Inclusion Body Myopathy with Paget's Disease and Frontotemporal Dementia). Here, we studied the role IBMPFD-related mutants of VCP/p97 in autophagy. In contrast with the wild-type VCP/p97 protein or R155C or R191Q mutants, the P137L mutant was aggregate-prone...
2016: PloS One
Christopher P Webster, Emma F Smith, Andrew J Grierson, Kurt J De Vos
A GGGGCC hexanucleotide repeat expansion in the first intron of the C9orf72 gene is the most common genetic defect associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9ALS/FTD). Haploinsufficiency and a resulting loss of C9orf72 protein function has been suggested as a possible pathogenic mechanism in C9ALS/FTD. C9ALS/FTD patients exhibit specific ubiquitin and p62/sequestosome-1 positive but TDP-43 negative inclusions in the cerebellum and hippocampus, indicating possible autophagy deficits in these patients...
October 21, 2016: Small GTPases
Shuai Gao, Man Pan, Yong Zheng, Yichao Huang, Qingyun Zheng, Demeng Sun, Lining Lu, Xiaodan Tan, Xianglong Tan, Huan Lan, Jiaxing Wang, Tian Wang, Jiawei Wang, Lei Liu
Racemic or quasi-racemic crystallography recently emerges as a useful technology for solution of the crystal structures of biomacromolecules. It remains unclear to what extent the biomacromolecules of opposite handedness can differ from each other in racemic or quasi-racemic crystallography. Here we report a finding that monomeric d-ubiquitin (Ub) has propensity to cocrystallize with different dimers, trimers, and even a tetramer of l-Ub. In these cocrystals the unconnected monomeric d-Ubs can self-assemble to form pseudomirror images of different oligomers of l-Ub...
October 21, 2016: Journal of the American Chemical Society
Wenqi Yang, Wei Zhang, Xiaoxue Wang
The plant phytohormone abscisic acid (ABA) plays significant roles in integrating environmental signals with embryogenesis, germination, seedling establishment, the floral transition, and the adaptation of plants to stressful environments by modulating stomatal movement and stress-responsive gene expression. ABA signaling consists of ABA perception, signal transduction, and ABA-induced responses. ABA receptors such as members of the PYR/PYL family, group A type 2C protein phosphatases (as negative regulators), SnRK2 protein kinases (as positive regulators), bZIP transcription factors, and ion channels are key components of ABA signaling...
October 21, 2016: Plant Biotechnology Journal
Yi Ma, Jieying Yu, Jinglian Lin, Shaomin Wu, Shan Li, Jufang Wang
Human epidermal growth factor (hEGF) is a small, mitotic growth polypeptide that promotes the proliferation of various cells and is widely applied in clinical practices. However, high efficient expression of native hEGF in Escherichia coli has not been successful, since three disulfide bonds in monomer hEGF made it unable to fold into correct 3D structure using in vivo system. To tackle this problem, we fused Mxe GyrA intein (Mxe) at the C-terminal of hEGF followed by small ubiquitin-related modifier (SUMO) and 10x His-tag to construct a chimeric protein hEGF-Mxe-SUMO-H10...
2016: BioMed Research International
Chae Lim Jung, Hyemin Mun, Se-Young Jo, Ju-Hee Oh, ChuHee Lee, Eun-Kyung Choi, Se Jin Jang, Young-Ah Suh
Mutation of p53 occasionally results in a gain of function, which promotes tumor growth. We asked whether destabilizing the gain-of-function protein would kill tumor cells. Downregulation of the gene reduced cell proliferation in p53-mutant cells, but not in p53-null cells, indicating that the former depended on the mutant protein for survival. Moreover, phenformin and 2-deoxyglucose suppressed cell growth and simultaneously destabilized mutant p53. The AMPK pathway, MAPK pathway, chaperone proteins and ubiquitination all contributed to this process...
October 19, 2016: Oncotarget
Akira Katsube, Hisamitsu Hayashi, Hiroyuki Kusuhara
OBJECTIVE: ATP-binding cassette transporter A1 (ABCA1) exerts an atheroprotective action through the biogenesis of high-density lipoprotein in hepatocytes and prevents the formation of foam cells from macrophages. Controlling ABCA1 is a rational approach to improving atherosclerotic cardiovascular disease. Although much is known about the regulatory mechanism of ABCA1 synthesis, the molecular mechanism underpinning its degradation remains to be clearly described. APPROACH AND RESULTS: ABCA1 possesses potential sites of phosphorylation by serine/threonine-protein kinase Pim-1 (Pim-1)...
October 20, 2016: Arteriosclerosis, Thrombosis, and Vascular Biology
Yuhang Zhou, Shaji Abraham, Stephanie Renna, Leonard C Edelstein, Carol A Dangelmaier, Alexander Y Tsygankov, Satya P Kunapuli, Paul F Bray, Steven E McKenzie
OBJECTIVE: The objective of this study is to investigate the role of T-cell ubiquitin ligand-2 (TULA-2) in the platelet Fc receptor for IgG IIA (FcγRIIA) pathway and in the pathogenesis of heparin-induced thrombocytopenia (HIT). APPROACH AND RESULTS: HIT is a life-threatening thrombotic disease in which IgG antibodies against the heparin-platelet factor 4 complex activate platelets via FcγRIIA. We reported previously differential expression of TULA-2 in human population was linked to FcγRIIA responsiveness...
October 20, 2016: Arteriosclerosis, Thrombosis, and Vascular Biology
Bingxian Yang, Qijie Guan, Jingkui Tian, Setsuko Komatsu
: High level of UV-B irradiation followed by dark treatment (HUV-B+D) causes accumulation of secondary metabolites in Clematis terniflora DC. To investigate the response mechanism under HUV-B+D, transcriptomic and proteomic analyses were performed in leaves of C. terniflora. The number of genes related to tetrapyrrole synthesis, amino acid metabolism, tricarboxylic acid cycle, and mitochondrial electron transport chains was hierarchically changed in leaves of C. terniflora under HUV-B+D...
October 17, 2016: Journal of Proteomics
Manuela Antonioli, Martina Di Rienzo, Mauro Piacentini, Gian Maria Fimia
Autophagy is a major degradative process activated in a rapid and transient manner to cope with stress conditions. Whether autophagy is beneficial or detrimental depends upon the rate of induction and the appropriateness of the duration. Alterations in both autophagy initiation and termination predispose the cell to death, and affect the execution of other inducible processes such as inflammation. In this review we discuss how stress signaling pathways dynamically control the activity of the autophagy machinery by mediating post-translational modifications and regulatory protein interactions...
October 17, 2016: Trends in Biochemical Sciences
Yoo Seob Shin, Sung Un Kang, Ju Kyeong Park, Yang Eun Kim, Yeon Soo Kim, Seung Joon Baek, Seong-Ho Lee, Chul-Ho Kim
BACKGROUND AND PURPOSE: Aberrant expression of β-catenin is highly associated with progression of various cancers including head and neck cancer (HNC). Green tea is most commonly used beverage in the world and one of the more bioactive compounds is the antioxidant epigallocatechin gallate (EGCG). This study was performed to investigate the mechanism by which EGCG inhibits the growth of HNC, focusing on the modulation of the expression and activity of β-catenin. METHODS: In vitro effects of EGCG on the transcription, translation, or degradation of β-catenin were investigated...
November 15, 2016: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
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