共查询到20条相似文献，搜索用时 31 毫秒
1.
Poonam Gupta Pratibha Singh Hriday S. Pandey Pankaj Seth Chinmay K. Mukhopadhyay 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(3):547-564
Background
Elevated endogenous phosphoinositide-3-kinase (PI3K) activity is critical for cell proliferation in gliomas. Iron availability is one of the essential factors for cell growth and proliferation. However, any relation between PI3K and cellular iron homeostasis has not been understood so far.Methods
Glioma cells and human primary astrocytes were treated with class I PI3K inhibitors to examine regulation of iron homeostasis components. Regulation of ferritin was detected at mRNA and translational level. Labile iron pool (LIP) and cell proliferation were examined in glioma cells and human primary astrocytes.Results
Blocking of PI3K activity elevated ferritin level by 6–10 folds in glioma cells by augmenting mRNA expression of ferritin subunits and also by influencing ferritin translation. IRE-IRP interaction was affected due to conversion of IRP1 to cytosolic aconitase that was influenced by increased iron-sulfur scaffold protein iron-sulfur cluster assembly enzyme (ISCU) level. Elevated ferritin sequestered LIP to affect cell proliferation that was reversed in silencing ferritin by siRNAs of ferritin-H and ISCU. Human primary astrocyte with little PI3K activity did not show any change in ferritin level, LIP and cell proliferation by PI3K inhibitors.Conclusions
PI3K inhibition promotes ferritin synthesis by dual mechanism resulting sequestration of iron to limit its availability for cell proliferation in glioma cells but not in primary astrocytes.General Significance: This observation establishes a relation between PI3K signalling and iron homeostasis in glioma cells. It also implies that activated PI3K controls ferritin expression to ensure availability of adequate iron required for cell proliferation. 相似文献2.
Thorsten Saenger Stefan Vordenbäumen Swetlana Genich Samer Haidar Marten Schulte Christian Nienberg Ellen Bleck Matthias Schneider Joachim Jose 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(3):632-643
Background
The milk protein αS1-casein was recently reported to induce secretion of proinflammatory cytokines via Toll-like receptor 4 (TLR4). In this study, αS1-casein was identified as binder of theTLR4 ecto domain.Methods
IL-8 secretion after stimulation of TLR4/MD2 (myeloid differentiation factor 2)/CD14 (cluster of differentiation 14)-transfected HEK293 cells (TLR4+) and Mono Mac 6 cells (MM6) with recombinant αS1-casein, or LPS as control was monitored. Binding of αS1-casein to TLR4 was quantified by microscale thermophoresis (MST).Results
αS1-casein induced secretion of IL-8 in TLR4+ cells and in MM6 cells with a six-times higher final IL-8 concentration in supernatants. IL-8 secretion was inhibited by intracellular TLR4-domain antagonist TAK-242 with an IC50-value of 259.6?nM, by ecto-domain TLR4 antagonistic mianserin with 10–51?μM and by anti-CD14-IgA. The binding constants (KD) of αS1-casein to the TLR4, MD2, and CD14 were 2.8?μM, 0.3?μM and 2.7?μM, respectively. Finally, αS1-casein showed a higher affinity to TLR4/MD2 (KD: 2.2?μM) compared to LPS (KD: 8.2?μM).Conclusion
Human αS1-casein induced proinflammatory effects are dependent upon binding to the TLR4 ectodomain and the presence of CD14. αS1-casein displayed stronger TLR4 agonistic activity than LPS via a different mode of action.General significance
Breast milk protein αS1-casein is a proinflammatory cytokine. 相似文献3.
Marilene Demasi Fernanda Marques da Cunha 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(12):2948-2954
Background
It has been almost three decades since the removal of oxidized proteins by the free 20S catalytic unit of the proteasome (20SPT) was proposed. Since then, experimental evidence suggesting a physiological role of proteolysis mediated by the free 20SPT has being gathered.Scope of review
Experimental data that favors the hypothesis of free 20SPT as playing a role in proteolysis are critically reviewed.Major conclusions
Protein degradation by the proteasome may proceed through multiple proteasome complexes with different requirements though the unequivocal role of the free 20SPT in cellular proteolysis towards native or oxidized proteins remains to be demonstrated.General significance
The biological significance of proteolysis mediated by the free 20SPT has been elusive since its discovery. The present review critically analyzes the available experimental data supporting the proteolytic role of the free or single capped 20SPT. 相似文献4.
Jia Hao Yeo Chanukya K. Colonne Nuren Tasneem Matthew P. Cosgriff Stuart T. Fraser 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(2):466-471
Background
A healthy human can produce over 1?×?1015 blood cells throughout their life. This remarkable amount of biomass requires a concomitantly vast amount of iron to generate functional haemoglobin and functional erythrocytes.Scope of the review
Erythroblasts form multicellular clusters with macrophages in the foetal liver, bone marrow and spleen termed erythroblastic islands. How the central erythroblastic island macrophage co-ordinates the supply of iron to the developing erythroblasts will be a central focus of this review.Major conclusion
Despite being studied for over 60?years, the mechanisms by which the erythroblastic island niche serves to control erythroid cell iron metabolism are poorly resolved.General significance
Over 2 billion people suffer from some form of anaemia. Iron deficiency anaemia is the most prevalent form of anaemia. Therefore, understanding the processes by which iron is trafficked to, and metabolised in developing erythrocytes, is crucially important. 相似文献5.
Xiaorui Fan William D. Barshop Ajay A. Vashisht Vijaya Pandey Stephanie Leal Shima Rayatpisheh Yasaman Jami-Alahmadi Jihui Sha James A. Wohlschlegel 《The Journal of biological chemistry》2022,298(7)
The cytosolic iron–sulfur (Fe-S) cluster assembly (CIA) pathway delivers Fe-S clusters to nuclear and cytosolic Fe-S proteins involved in essential cellular functions. Although the delivery process is regulated by the availability of iron and oxygen, it remains unclear how CIA components orchestrate the cluster transfer under varying cellular environments. Here, we utilized a targeted proteomics assay for monitoring CIA factors and substrates to characterize the CIA machinery. We find that nucleotide-binding protein 1 (NUBP1/NBP35), cytosolic iron–sulfur assembly component 3 (CIAO3/NARFL), and CIA substrates associate with nucleotide-binding protein 2 (NUBP2/CFD1), a component of the CIA scaffold complex. NUBP2 also weakly associates with the CIA targeting complex (MMS19, CIAO1, and CIAO2B) indicating the possible existence of a higher order complex. Interactions between CIAO3 and the CIA scaffold complex are strengthened upon iron supplementation or low oxygen tension, while iron chelation and reactive oxygen species weaken CIAO3 interactions with CIA components. We further demonstrate that CIAO3 mutants defective in Fe-S cluster binding fail to integrate into the higher order complexes. However, these mutants exhibit stronger associations with CIA substrates under conditions in which the association with the CIA targeting complex is reduced suggesting that CIAO3 and CIA substrates may associate in complexes independently of the CIA targeting complex. Together, our data suggest that CIA components potentially form a metabolon whose assembly is regulated by environmental cues and requires Fe-S cluster incorporation in CIAO3. These findings provide additional evidence that the CIA pathway adapts to changes in cellular environment through complex reorganization. 相似文献
6.
Sophie Winkler Rupert Derler Bernd Gesslbauer Elmar Krieger Andreas J. Kungl 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(3):528-533
Background
Binding of chemokines to glycosaminoglycans (GAGs) is a crucial step in leukocyte recruitment to inflamed tissues.Methods
A disaccharide compositional analysis of the HS dp6 fraction in combination with MS analysis of the CCL2-depleted dp6 fraction was the basis for target GAG ligand structure suggestions. Four experimentally-derived heparan sulfate hexasaccharides, two potentially chemokine-specific and two unspecific, have been docked to CCL2. Subsequent 300?ns molecular dynamics simulations were used to improve the docked complexes.Results
Hexasaccharides with four sulfations and no acetylations are suggested for selective and high affinity chemokine binding. Using the Antithromin-III/heparin complex as positive control for docking, we were able to recover the correct complex structure only if the previously liganded ATIII structure was used as input. Since the liganded structure is not known for a CCL2-GAG complex, we investigated if molecular dynamics simulations could improve initial docking results. We found that all four GAG oligosaccharides ended up in close contact with the known binding residues after about 100?ns simulation time.Conclusions
A discrimination of specific vs. unspecific CCL2 GAG ligands is not possible by this approach. Long-time molecular dynamics simulations are, however, well suited to capture the delicate enthalpy/entropy balance of GAG binding and improve results obtained from docking.General significance
With the comparison of two methods, MS-based ligand identification and molecular modelling, we have shown the current limitations of our molecular understanding of complex ligand binding which is could be due to the numerical inaccessibility of ligand-induced protein conformational changes. 相似文献7.
Ida Autiero Menotti Ruvo Roberto Improta Luigi Vitagliano 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(4):1006-1016
Background
Aptamers are RNA/DNA biomolecules representing an emerging class of protein interactors and regulators. Despite the growing interest in these molecules, current understanding of chemical-physical basis of their target recognition is limited. Recently, the characterization of the aptamer targeting the protein-S8 has suggested that flexibility plays important functional roles. We investigated the structural versatility of the S8-aptamer by molecular dynamics simulations.Methods
Five different simulations have been conducted by varying starting structures and temperatures.Results
The simulation of S8-aptamer complex provides a dynamic view of the contacts occurring at the complex interface. The simulation of the aptamer in ligand-free state indicates that its central region is intrinsically endowed with a remarkable flexibility. Nevertheless, none of the trajectory structures adopts the structure observed in the S8-aptamer complex. The aptamer ligand-bound is very rigid in the simulation carried out at 300?K. A structural transition of this state, providing insights into the aptamer-protein recognition process, is observed in a simulation carried out at 400?K. These data indicate that a key event in the binding is linked to the widening of the central region of the aptamer. Particularly relevant is switch of the A26 base from its ligand-free state to a location that allows the G13-C28 base-pairing.Conclusions
Intrinsic flexibility of the aptamer is essential for partner recognition. Present data indicate that S8 recognizes the aptamer through an induced-fit rather than a population-shift mechanism.General significance
The present study provides deeper understanding of the structural basis of the structural versatility of aptamers. 相似文献8.
Nathalie Vaes Simone L. Schonkeren Erwin Brosens Alexander Koch Conor J. McCann Nikhil Thapar Robert M.W. Hofstra Manon van Engeland Veerle Melotte 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(10):2140-2151
Background
The N-Myc Downstream-Regulated Gene (NDRG) family comprises four members that function in cellular processes like proliferation and differentiation. While NDRG1 and NDRG2 are extensively studied, knowledge regarding NDRG3 and NDRG4, despite its recognition as a well-established early-detection marker for colorectal cancer (Cologuard®), is sparse.Scope of review
To summarize expression, biomarker potential and functional mechanisms of the NDRGs in the developing, mature and cancerous gut, we combine current literature and in silico analyses from the TCGA-database, GTEX Project, E14.5 mouse intestine and enteric neural crest cells, and an RNA-sequencing time-series of human embryonic colonic samples.Major conclusions
This study reveals that all members display a differential expression pattern in the gut and that NDRG1, NDRG2 and NDRG4 (1) can serve as biomarker for colorectal cancer and (2) have tumor suppressive properties mainly affecting cell proliferation and epithelial-mesenchymal transition.General significance
Similar effects of the NDRGs on the key-hallmarks of cancer, could implicate analogous functions in other tissue/cancer types. 相似文献9.
Rosario Iglesias J. Miguel Ferreras Antimo Di Maro Lucía Citores 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(3):460-473
Background
Sambucus ebulus is a rich source of ribosome-inactivating proteins (RIPs) and RIP-related lectins generated from multiple genes. These proteins differ in their structure, enzymatic activity and sugar binding specificity.Methods
We have purified and characterized ebulin-RP from S. ebulus leaves and determined the amino acid sequence by cDNA cloning. Cytotoxicity was studied in a variety of cancer cells and a comparative study of the ability of ebulin-RP to bind sugars using “in vitro” and “in silico” approaches was performed.Results
Ebulin-RP is a novel heterodimeric type 2 RIP present in S. ebulus leaves together with the type 2 RIP ebulin l, which displayed rRNA N-glycosidase activity but unlike ebulin l, lacked functional sugar binding domains. As a consequence of changes in its B-chain, ebulin-RP displayed lower cytotoxicity than ebulin l towards cancer cells and induced apoptosis as the predominant pattern of cell death.Conclusions
Ebulin-RP is a novel member of the ebulin gene family with low cytotoxicity as a result of deficient sugar binding domains. Type 2 RIP genes from Sambucus have evolved to render proteins with different sugar affinities that may be related to different biological activities and could result in an advantage for the plant.General significance
The ebulin family of RIPs and lectins can serve as a good model for studying the evolutionary process which may have occurred in RIPs. The lack of cytotoxicity of ebulin-RP makes it a good candidate as a toxic moiety in the construction of immunotoxins and conjugates directed against specific targets. 相似文献10.
Rajshri Singh Priya Dagar Shyama Pal Bhakti Basu Bhavani S. Shankar 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(3):669-683
Background
Tumor microenvironment is composed of a largely altered extracellular matrix with different cell types. The complex interplay between macrophages and tumor cells through several soluble factors and signaling is an important factor in breast cancer progression.Methods
We have extended our earlier studies on monocyte and macrophage conditioned medium (M?CM) and have carried out proteomic analysis to identify its constituents as well as validation. The 8-gene signature identified through macrophage-breast cancer cell interactions was queried in cBioportal for bioinformatic analyses.Results
Proteomic analysis (MALDI-TOF and LC-MS/MS) revealed integrin and matrix metalloproteinases in M?CM which activated TGF-β1, IL-6, TGF- βRII and EGFR as well as its downstream STAT and SMAD signaling in breast cancer cells. Neutralization of pro-inflammatory cytokines (TNF-α. Il-1β, IL-6) abrogated the M?CM induced migration but invasion to lesser extent. The 8- gene signature identified by macrophage-tumor interactions (TNF-α, IL-1β, IL-6, MMP1, MMP9, TGF-β1, TGF-βRII, EGFR) significantly co-occurred with TP53 mutation, WTAPP1 deletion and SLC12A5 amplification along with differential expression of PSAT1 and ESR1 at the mRNA level and TPD52and PRKCD at the protein level in TCGA (cBioportal). Together these genes form a novel 15 gene signature which is altered in 63.6% of TCGA (1105 samples) data and was associated with high risk and poor survival (p < 0.05) in many breast cancer datasets (SurvExpress).Conclusions
These results highlight the importance of macrophage signaling in breast cancer and the prognostic role of the15-gene signature.General significance
Our study may facilitate novel prognostic markers based on tumor-macrophage interaction. 相似文献11.
Joe Varghese Jithu James Sophie Vaulont Andrew Mckie Molly Jacob 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(9):1870-1882
Background
An iron-overloaded state has been reported to be associated with insulin resistance. On the other hand, conditions such as classical hemochromatosis (where iron overload occurs primarily in the liver) have been reported to be associated with increased insulin sensitivity. The reasons for these contradictory findings are unclear. In this context, the effects of increased intracellular iron per se on insulin signaling in hepatocytes are not known.Methods
Mouse primary hepatocytes were loaded with iron in vitro by incubation with ferric ammonium citrate (FAC). Intracellular events related to insulin signaling, as well as changes in gene expression and hepatocyte glucose production (HGP), were studied in the presence and absence of insulin and/or forskolin (a glucagon mimetic).Results
In vitro iron-loading of hepatocytes resulted in phosphorylation-mediated activation of Akt and AMP-activated protein kinase. This was associated with decreased basal and forskolin-stimulated HGP. Iron attenuated forskolin-mediated induction of the key gluconeogenic enzyme, glucose-6-phosphatase. It also attenuated activation of the Akt pathway in response to insulin, which was associated with decreased protein levels of insulin receptor substrates 1 and 2, constituting insulin resistance.Conclusions
Increased intracellular iron has dual effects on insulin sensitivity in hepatocytes. It increased basal activation of the Akt pathway, but decreased activation of this pathway in response to insulin.General significance
These findings may help explain why both insulin resistance and increased sensitivity have been observed in iron-overloaded states. They are of relevance to a variety of disease conditions characterized by hepatic iron overload and increased risk of diabetes. 相似文献12.
Katarina Psenakova Olivia Petrvalska Salome Kylarova Domenico Lentini Santo Dana Kalabova Petr Herman Veronika Obsilova Tomas Obsil 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(7):1612-1625
Background
Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is a member of the Ca2+/calmodulin-dependent kinase (CaMK) family involved in adiposity regulation, glucose homeostasis and cancer. This upstream activator of CaMKI, CaMKIV and AMP-activated protein kinase is inhibited by phosphorylation, which also triggers an association with the scaffolding protein 14-3-3. However, the role of 14-3-3 in the regulation of CaMKK2 remains unknown.Methods
The interaction between phosphorylated CaMKK2 and the 14-3-3γ protein, as well as the architecture of their complex, were studied using enzyme activity measurements, small-angle x-ray scattering (SAXS), time-resolved fluorescence spectroscopy and protein crystallography.Results
Our data suggest that the 14-3-3 protein binding does not inhibit the catalytic activity of phosphorylated CaMKK2 but rather slows down its dephosphorylation. Structural analysis indicated that the complex is flexible and that CaMKK2 is located outside the phosphopeptide-binding central channel of the 14-3-3γ dimer. Furthermore, 14-3-3γ appears to interact with and affect the structure of several regions of CaMKK2 outside the 14-3-3 binding motifs. In addition, the structural basis of interactions between 14‐3-3 and the 14-3-3 binding motifs of CaMKK2 were elucidated by determining the crystal structures of phosphopeptides containing these motifs bound to 14-3-3.Conclusions
14-3-3γ protein directly interacts with the kinase domain of CaMKK2 and the region containing the inhibitory phosphorylation site Thr145 within the N-terminal extension.General significance
Our results suggested that CaMKK isoforms differ in their 14-3-3-mediated regulations and that the interaction between 14-3-3 protein and the N-terminal 14-3-3-binding motif of CaMKK2 might be stabilized by small-molecule compounds. 相似文献13.
Huan He Juan Xu Wen Xie Qing-Lian Guo Feng-Lei Jiang Yi Liu 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(3):501-512
Background
CDK6 is considered as a highly validated anticancer drug target due to its essential role in regulating cell cycle progression at G1 restriction point. Activation of CDK6 requires the phosphorylation of Thr177 on A-loop, but the structural insights of the activation mechanism remain unclear.Methods
Herein, all-atoms molecular dynamics (MD) simulations were used to study the effects of Thr177 phosphorylation on the dynamic structure of CDK6-Vcyclin complex.Results
MD results indicated that the free energy barrier of the transition from open to closed state decreased ~ 47.2% after Thr177 phosphorylation. Key steps along the state transition process were obtained from a cluster analysis. Binding preference of ten different inhibitors to open or closed state were also investigated through molecular docking along with MD simulations methods.Conclusions
Our results indicated that Thr177 phosphorylation increased the flexibility around the ATP-binding pocket. The transition of the ATP-binding pocket between open and closed states should be considered for understanding the binding of CDK6 inhibitors.General significance
This work could deepen the understanding of CDKs activation mechanism, and provide useful information for the discovery of new CDKs inhibitors with high affinity and specificity. 相似文献14.
Patricia Santofimia-Castaño Bruno Rizzuti Olga Abián Adrián Velázquez-Campoy Juan L. Iovanna José L. Neira 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(6):1283-1295
Background
NUPR1 is a multifunctional intrinsically disordered protein (IDP) involved, among other functions, in chromatin remodelling, and development of pancreatic ductal adenocarcinoma (PDAC). It interacts with several biomolecules through hydrophobic patches around residues Ala33 and Thr68. The drug trifluoperazine (TFP), which hampers PDAC development in xenografted mice, also binds to those regions. Because of the large size of the hot-spot interface of NUPR1, small molecules could not be adequate to modulate its functions.Methods
We explored how amphipathic helical-designed peptides were capable of interacting with wild-type NUPR1 and the Thr68Gln mutant, inhibiting the interaction with NUPR1 protein partners. We used in vitro biophysical techniques (fluorescence, circular dichroism (CD), nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC)), in silico studies (docking and molecular dynamics (MD)), and in cellulo protein ligation assays (PLAs) to study the interaction.Results
Peptide dissociation constants towards wild-type NUPR1 were ~ 3?μM, whereas no interaction was observed with the Thr68Gln mutant. Peptides interacted with wild-type NUPR1 residues around Ala33 and residues at the C terminus, as shown by NMR. The computational results clarified the main determinants of the interactions, providing a mechanism for the ligand-capture that explains why peptide binding was not observed for Thr68Gln mutant. Finally, the in cellulo assays indicated that two out of four peptides inhibited the interaction of NUPR1 with the C-terminal region of the Polycomb RING protein 1 (C-RING1B).Conclusions
Designed peptides can be used as lead compounds to inhibit NUPR1 interactions.General significance
Peptides may be exploited as drugs to target IDPs. 相似文献15.
Danfeng Shi Shuangyan Zhou Xuewei Liu Chenxi Zhao Huanxiang Liu Xiaojun Yao 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(3):576-588
Background
The inhibitors blocking the interaction between programmed cell death protein 1(PD-1) and programmed death-ligand 1(PD-L1) can activate the immune response of T cell and eliminate cancer cells. The crystallographic studies have provided structural insights of the interactive interfaces between PD-L1 and its protein ligands. However, the hotspot residues on PD-L1 as well as structural and energetic basis for different protein ligands still need to be further investigated.Methods
Molecular modeling methods including molecular dynamics simulation, per-residue free energy decomposition, virtual alanine scanning mutagenesis and residue-residue contact analysis were used to qualitatively and quantitatively analyze the interactions between PD-L1 and different protein ligands.Results
The results of virtual alanine scanning mutagenesis suggest that Y56, Q66, M115, D122, Y123, R125 are the hotspot residues on PD-L1. The residue-residue contact analysis further shows that PD-1 interacts with PD-L1 mainly by F and G strands while monoclonal antibodies like avelumab and BMS-936559 mainly interact with PD-L1 by CDR2 and CDR3 loops of the heavy chain.Conclusions
A structurally similar β-hairpin peptide with 13 or 14 residues was extracted from each protein ligand and these β-hairpin peptides were found tightly binding to the putative hotspot residues on PD-L1.General significance
This study recognizes the hotspot residues on PD-L1 and uncovers the common structural and energetic basis of different protein ligands binding to PD-L1. These results will be valuable for the design of small molecule or peptide inhibitors targeting on PD-L1. 相似文献16.
Viacheslav V. Senichkin Gelina S. Kopeina Eugeniia A. Prokhorova Alexey V. Zamaraev Inna N. Lavrik Boris Zhivotovsky 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(3):557-566
Background
The development of approaches that increase therapeutic effects of anti-cancer drugs is one of the most important tasks of oncology. Caloric restriction in vivo or serum deprivation (SD) in vitro has been shown to be an effective tool for sensitizing cancer cells to chemotherapeutic drugs. However, the detailed mechanisms underlying the enhancement of apoptosis in cancer cells by SD remain to be elucidated.Methods
Flow cytometry, caspase activity assay and western blotting were used for cell death rate evaluation. Western blotting, gel-filtration, siRNA approach and qRT-PCR were used to elucidate the mechanism underlying cell death potentiation upon SD.Results
We demonstrated that SD sensitizes cancer cells to treatment with chemotherapeutic agent cisplatin. This effect is independent on activation of caspases-2 and -8, apical caspases triggering apoptosis in response to genotoxic stress. SD potentiates cell death via downregulation of the anti-apoptotic protein Mcl-1. In fact, SD reduces the Mcl-1 mRNA level, which consequently decreases the Mcl-1 protein level and renders cells more susceptible to apoptosis induction via the formation of apoptosome.Conclusions
Mcl-1 protein is an important regulator of sensitivity of cancer cells to apoptotic stimuli upon SD.General significance
This study identifies Mcl-1 as a new target for the sensitization of human cancer cells to cell death by SD, which is of great significance for the development of efficient anti-cancer therapies. 相似文献17.
Seong-Cheol Park Il Ryong Kim Jin-Young Kim Yongjae Lee Eun-Ji Kim Ji Hyun Jung Young Jun Jung Mi-Kyeong Jang Jung Ro Lee 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(12):2545-2554
Background
It remains an open question whether plant phloem sap proteins are functionally involved in plant defense mechanisms.Methods
The antifungal effects of two profilin proteins from Arabidopsis thaliana, AtPFN1 and AtPFN2, were tested against 11 molds and 4 yeast fungal strains. Fluorescence profiling, biophysical, and biochemical analyses were employed to investigate their antifungal mechanism.Results
Recombinant AtPFN1 and AtPFN2 proteins, expressed in Escherichia coli, inhibited the cell growth of various pathogenic fungal strains at concentrations ranging from 10 to 160?μg/mL. The proteins showed significant intracellular accumulation and cell-binding affinity for fungal cells. Interestingly, the AtPFN proteins could penetrate the fungal cell wall and membrane and act as inhibitors of fungal growth via generation of cellular reactive oxygen species and mitochondrial superoxide. This triggered the AtPFN variant-induced cell apoptosis, resulting in morphological changes in the cells.Conclusion
PFNs may play a critical role as antifungal proteins in the Arabidopsis defense system against fungal pathogen attacks.General significance
The present study indicates that two profilin proteins, AtPFN1 and AtPFN2, can act as natural antimicrobial agents in the plant defense system. 相似文献18.
Elisabetta Galbiati Svetlana Avvakumova Alessandra La Rocca Maria Pozzi Silvia Messali Paola Magnaghi Miriam Colombo Davide Prosperi Paolo Tortora 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(10):2254-2260
Background
Vaults are eukaryotic ribonucleoprotein particles composed of up 78 copies of the 97?kDa major vault protein that assembles into a barrel-like, “nanocapsule” enclosing poly(ADP-ribose) polymerase, telomerase-associated protein-1 and small untranslated RNAs. Overall, the molecular mass of vault particles amounts to about 13?MDa. Although it has been implicated in several cellular functions, its physiological roles remain poorly understood. Also, the possibility to exploit it as a nanovector for drug delivery is currently being explored in several laboratories.Methods
Using the baculovirus expression system, vaults were expressed and purified by a dialysis step using a 1?MDa molecular weight cutoff membrane and a subsequent size exclusion chromatography. Purity was assessed by SDS-PAGE, transmission electron microscopy and dynamic light scattering. Particle's endocytic uptake was monitored by flow cytometry and confocal microscopy.Results
The purification protocol here reported is far simpler and faster than those currently available and lead to the production of authentic vault. We then demonstrated its clathrin-mediated endocytic uptake by normal fibroblast and glioblastoma, but not carcinoma cell lines. In contrast, no significant caveolin-mediated endocytosis was detected.Conclusions
These results provide the first evidence for an intrinsic propensity of the vault complex to undergo endocytic uptake cultured eukaryotic cells.General significance
The newly developed purification procedure will greatly facilitate any investigation based on the use of the vault particle as a natural nanocarrier. Its clathrin-mediated endocytic uptake observed in normal and in some tumor cell lines sheds light on its physiological role. 相似文献19.
Hyeonjun Kim Hyejin Kim Jeong K. Lee 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(12):2674-2687
Background
Protoporphyrin IX (PPn), an intermediate in the heme biosynthesis reaction, generates singlet oxygen upon exposure to UV light. It has been proposed that PPn is channeled directly to ferrochelatase within a protoporphyrinogen dehydrogenase (PgdH1)-protoporphyrin ferrochelatase (PpfC) complex as a way to avoid this damaging side reaction. However, the PgdH1-PpfC complex has not been characterized, and the question of how heme affects the activities of PgdH1 has not been addressed.Methods
Protein interactions were explored through pull-down assays and western blotting, and the importance of this complex in vivo was examined using inter-species combinations of the two proteins. The purified PgdH1-PpfC complex was characterized kinetically and used for heme binding studies.Results
In Vibrio vulnificus, PgdH1 and PpfC formed an 8:8 heterohexadecameric complex that was important for maintaining PPn at low levels. PpfC catalyzed PPn efficiently whether or not it was part of the complex. Notably, heme was a noncompetitive inhibitor of V. vulnificus PgdH1, but a competitive inhibitor of the human protoporphyrinogen oxidase PgoX.Conclusion
The PdgH1-PpfC complex is important for protective channeling of PPn and for efficient catalysis of free PPn. The production of PPn by PgdH1 is regulated by feedback inhibition by heme.General significance
Both proteobacteria and eukaryotes have evolved mechanisms to prevent the harmful accumulation of the heme biosynthesis intermediate PPn. The data presented here suggest two previously unknown mechanisms: the channeling of PPn through the PgdH1-PpfC complex, and the direct inhibition of PgdH1 activity (PgoX activity as well) by heme. 相似文献20.
Sarah Caughlin Shikhar Maheshwari Yuksel Agca Cansu Agca Aaron J. Harris Kristina Jurcic Ken K.-C. Yeung David F. Cechetto Shawn N. Whitehead 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(6):1327-1338