共查询到20条相似文献，搜索用时 62 毫秒
1.
Hana Popelka 《Autophagy》2017,13(3):449-451
Atg13 is an essential subunit of the Atg1 autophagy initiation complex in yeast and its mammalian counterpart, ATG13, is indispensable for autophagy induction by the ULK1 complex. The N terminus of the protein folds into a HORMA domain, an architecture that has been revealed by crystallography.1-4 In human cells, the ATG13 HORMA domain interacts directly with ATG14, a subunit of the class III phosphatidylinositol 3-kinase complex.5 In budding yeast, the HORMA domain of Atg13 recruits Atg14, but a direct interaction remains to be proven.1 The amino acid sequence that follows the HORMA domain does not adopt any 3-dimensional structure on its own; therefore, it is termed an intrinsically disordered region (IDR). Here we discuss the results of 2 recent studies in light of previous reports on Atg13 from yeast. Together, they yield an insight into the molecular mechanism for the function of this intriguing protein, and reveal why Atg13, as well as the mammalian homolog ATG13, cannot have a structurally rigid architecture. 相似文献
2.
3.
Beate Hintersteiner Nico Lingg Peiqing Zhang Susanto Woen Kong Meng Hoi Stefan Stranner 《MABS-AUSTIN》2016,8(8):1548-1560
We identified active isoforms of the chimeric anti-GD2 antibody, ch14.18, a recombinant antibody produced in Chinese hamster ovary cells, which is already used in clinical trials.1,2,3 We separated the antibody by high resolution ion-exchange chromatography with linear pH gradient elution into acidic, main and basic charge variants on a preparative scale yielding enough material for an in-depth study of the sources and the effects of microheterogeneity. The binding affinity of the charge variants toward the antigen and various cell surface receptors was studied by Biacore. Effector functions were evaluated using cellular assays for antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. Basic charge variants showed increased binding to cell surface receptor FcγRIIIa, which plays a major role in regulating effector functions. Furthermore, increased binding of the basic fractions to the neonatal receptor was observed. As this receptor mediates the prolonged half-life of IgG in human serum, this data may well hint at an increased serum half-life of these basic variants compared to their more acidic counterparts. Different glycoform patterns, C-terminal lysine clipping and N-terminal pyroglutamate formation were identified as the main structural sources for the observed isoform pattern. Potential differences in structural stability between individual charge variant fractions by nano differential scanning calorimetry could not been detected. Our in-vitro data suggests that the connection between microheterogeneity and the biological activity of recombinant antibody therapeutics deserves more attention than commonly accepted. 相似文献
4.
Pluripotent stem cells, including induced pluripotent and embryonic stem cells (ESCs), have less developed mitochondria than somatic cells and, therefore, rely more heavily on glycolysis for energy production.1-3 However, how mitochondrial homeostasis matches the demands of nuclear reprogramming and regulates pluripotency in ESCs is largely unknown. Here, we identified ATG3-dependent autophagy as an executor for both mitochondrial remodeling during somatic cell reprogramming and mitochondrial homeostasis regulation in ESCs. Dysfunctional autophagy by Atg3 deletion inhibited mitochondrial removal during pluripotency induction, resulting in decreased reprogramming efficiency and accumulation of abnormal mitochondria in established iPSCs. In Atg3 null mouse ESCs, accumulation of aberrant mitochondria was accompanied by enhanced ROS generation, defective ATP production and attenuated pluripotency gene expression, leading to abnormal self-renewal and differentiation. These defects were rescued by reacquisition of wild-type but not lipidation-deficient Atg3 expression. Taken together, our findings highlight a critical role of ATG3-dependent autophagy for mitochondrial homeostasis regulation in both pluripotency acquirement and maintenance. 相似文献
5.
《Cell Adhesion & Migration》2013,7(3):202-213
Neurons are highly polarized specialized cells. Neuronal integrity and functional roles are critically dependent on dendritic architecture and synaptic structure, function and plasticity. The cadherins are glycosylated transmembrane proteins that form cell adhesion complexes in various tissues. They are associated with a group of cytosolic proteins, the catenins. While the functional roles of the complex have been extensively investigates in non-neuronal cells, it is becoming increasingly clear that components of the complex have critical roles in regulating dendritic and synaptic architecture, function and plasticity in neurons. Consistent with these functional roles, aberrations in components of the complex have been implicated in a variety of neurodevelopmental disorders. In this review, we discuss the roles of the classical cadherins and catenins in various aspects of dendrite and synapse architecture and function and their relevance to human neurological disorders. Cadherins are glycosylated transmembrane proteins that were initially identified as Ca2+-dependent cell adhesion molecules. They are present on plasma membrane of a variety of cell types from primitive metazoans to humans. In the past several years, it has become clear that in addition to providing mechanical adhesion between cells, cadherins play integral roles in tissue morphogenesis and homeostasis. The cadherin family is composed of more than 100 members and classified into several subfamilies, including classical cadherins and protocadherins. Several of these cadherin family members have been implicated in various aspects of neuronal development and function.1-3 The classical cadherins are associated with a group of cytosolic proteins, collectively called the catenins. While the functional roles of the cadherin-catenin cell adhesion complex have been extensively investigated in epithelial cells, it is now clear that components of the complex are well expressed in central neurons at different stages during development.4,5 Recent exciting studies have shed some light on the functional roles of cadherins and catenins in central neurons. In this review, we will provide a brief overview of the cadherin superfamily, describe cadherin family members expressed in central neurons, cadherin-catenin complexes in central neurons and then focus on role of the cadherin-catenin complex in dendrite morphogenesis and synapse morphogenesis, function and plasticity. The final section is dedicated to discussion of the emerging list of neural disorders linked to cadherins and catenins. While the roles of cadherins and catenins have been examined in several different types of neurons, the focus of this review is their role in mammalian central neurons, particularly those of the cortex and hippocampus. Accompanying this review is a series of excellent reviews targeting the roles of cadherins and protocadherins in other aspects of neural development. 相似文献
6.
Avinashnarayan Venkatanarayan Payal Raulji William Norton 《Cell cycle (Georgetown, Tex.)》2016,15(2):164-171
TP53 is highly mutated in human cancers, thus targeting this tumor suppressor pathway is highly desirable and will impact many cancer patients.1,2 Therapeutic strategies to reactivate the p53-pathway have been challenging,3,4 and no effective treatment exists.5 We utilized the p53-family members, p63 and p73, which are not frequently mutated in cancer, to treat p53-defective cancers. The N-terminal splice variants of p63 and p73 are denoted as the TA and ΔN isoforms. We recently demonstrated that deletion of either ΔNp63 or ΔNp73 in p53-deficient mouse tumors results in tumor regression mediated by metabolic programming. Using this strategy, we identified pramlintide, a synthetic analog of amylin, as an effective treatment for p53 deficient and mutant tumors. Here, we show the utility of using pramlintide, as a potential cancer preventive option for p53-deficient tumors in mouse models. Additionally, we found that in vivo inhibition of both ΔNp63 and ΔNp73 in combination accelerates tumor regression and increases survival of p53-deficient mice. We report that inhibition of both ΔNp63 and ΔNp73 in combination results in upregulation of 3 key metabolic regulators, IAPP, GLS2, and TIGAR resulting in an increase in apoptosis and tumor regression in ΔNp63/ΔNp73/p53 deficient thymic lymphomas. These data highlight the value of generating inhibitors that will simultaneously target ΔNp63 and ΔNp73 to treat cancer patients with alterations in p53. 相似文献
7.
《朊病毒》2013,7(6):405-411
ABSTRACTWithin the mammalian prion field, the existence of recombinant prion protein (PrP) conformers with self-replicating (ie. autocatalytic) activity in vitro but little to no infectious activity in vivo challenges a key prediction of the protein-only hypothesis of prion replication – that autocatalytic PrP conformers should be infectious. To understand this dissociation of autocatalysis from infectivity, we recently performed a structural and functional comparison between a highly infectious and non-infectious pair of autocatalytic recombinant PrP conformers derived from the same initial prion strain.1 We identified restricted, C-terminal structural differences between these 2 conformers and provided evidence that these relatively subtle differences prevent the non-infectious conformer from templating the conversion of native PrPC substrates containing a glycosylphosphatidylinositol (GPI) anchor.1 In this article we discuss a model, consistent with these findings, in which recombinant PrP, lacking post-translational modifications and associated folding constraints, is capable of adopting a wide variety of autocatalytic conformations. Only a subset of these recombinant conformers can be adopted by post-translationally modified native PrPC, and this subset represents the recombinant conformers with high specific infectivity. We examine this model's implications for the generation of highly infectious recombinant prions and the protein-only hypothesis of prion replication. 相似文献
8.
Christopher J. Derrick 《Cell cycle (Georgetown, Tex.)》2017,16(1):23-32
Localized mRNA translation is a widespread mechanism for targeting protein synthesis, important for cell fate, motility and pathogenesis. In Drosophila, the spatiotemporal control of gurken/TGF-α mRNA translation is required for establishing the embryonic body axes. A number of recent studies have highlighted key aspects of the mechanism of gurken mRNA translational control at the dorsoanterior corner of the mid-stage oocyte. Orb/CPEB and Wispy/GLD-2 are required for polyadenylation of gurken mRNA, but unlocalized gurken mRNA in the oocyte is not fully polyadenylated.1 At the dorsoanterior corner, Orb and gurken mRNA have been shown to be enriched at the edge of Processing bodies, where translation occurs.2 Over-expression of Orb in the adjacent nurse cells, where gurken mRNA is transcribed, is sufficient to cause mis-expression of Gurken protein.3 In orb mutant egg chambers, reducing the activity of CK2, a Serine/Threonine protein kinase, enhances the ventralized phenotype, consistent with perturbation of gurken translation.4 Here we show that sites phosphorylated by CK2 overlap with active Orb and with Gurken protein expression. Together with our new findings we consolidate the literature into a working model for gurken mRNA translational control and review the role of kinases, cell cycle factors and polyadenylation machinery highlighting a multitude of conserved factors and mechanisms in the Drosophila egg chamber. 相似文献
9.
The Inter-Tribal Fisheries and Assessment Program (ITFAP) of the Chippewa Ottawa Resource Authority (CORA) in Sault Ste. Marie, Michigan, has been monitoring contaminant concentrations in the fillet portions of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) from the waters of lakes Superior, Huron, and Michigan since 1991. The primary purpose of this article is to present a risk quantification of methylmercury (MeHg) that is adjusted for nutritional benefit, originally presented by Ginsberg and Toal (2009, 2015) on trends in contaminant concentrations in fillet portions of these commercial fish that we recently reported in Dellinger et al. (2014). Both species of fish caught by tribal fishermen showed clear benefits to cardiovascular health and infant neurodevelopment if consumed at a rate of six ounces per week. However, other popularly consumed fish such as cod, tuna, and tilapia are estimated to have only marginal benefit or net negative effects on cardiovascular health and infant neurodevelopment. This dynamic assessment of benefits and risks further demonstrates the importance of traditionally caught fish in tribal health. 相似文献
10.
Sabine Elowe 《Cell cycle (Georgetown, Tex.)》2017,16(8):746-748
Tyrosine phosphorylation is rare, representing only about 0.5% of phosphorylations in the cell under basal conditions. While mitogenic tyrosine kinase signaling has been extensively explored, the role of phosphotyrosine signaling across the cell cycle and in particular during mitosis is poorly understood.
Two recent, independent studies tackled this question from different angles to reveal exciting new insights into the role of this modification during cell division. Caron et al.1 exploited mitotic phosphoproteomics data sets to determine the extent of mitotic tyrosine phosphorylation, and St-Denis et al.2 identified protein tyrosine phosphatases from all subfamilies as regulators of mitotic progression or spindle formation. These studied collectively revealed that tyrosine phosphorylation may play a more prominent and active role in mitotic progression than previously appreciated. 相似文献
11.
Sequestration of aggregates into specialized deposition sites occurs in many species across all kingdoms of life ranging from bacteria to mammals and is commonly believed to have a cytoprotective function. Yeast cells possess at least 3 different spatially separated deposition sites, one of which is termed “Insoluble Protein Deposit (IPOD)” and harbors amyloid aggregates. We have recently discovered that recruitment of amyloid aggregates to the IPOD uses an actin cable based recruitment machinery that also involves vesicular transport.1 Here we discuss how different proteins known to be involved in vesicular transport processes to the vacuole might act to guide amyloid aggregates to the IPOD. These factors include the Myosin V motor protein Myo2 involved in transporting vacuolar vesicles along actin cables, the transmembrane protein Atg9 involved in the recruitment of large precursor hydrolase complexes to the vacuole, the phosphatidylinositol/ phosphatidylcholine (PI/PC) transfer protein Sec 14 and the SNARE chaperone Sec 18. Furthermore, we present new data suggesting that the yeast dynamin homolog Vps1 is also crucial for faithful delivery of the amyloid model protein PrD-GFP to the IPOD. This is in agreement with a previously identified role for Vps1 in recruitment of heat-denatured aggregates to a perivacuolar deposition site.2 相似文献
12.
The existence of extrema, maximum and/or minimum and negative gradients of melting curves observed for several elements at high pressure is investigated by molecular dynamics simulation using the two-species model (TSM) proposed by Ogura et al. [1]. TSM is a model which imitates the change in the electronic structure of an atom in terms of a species change in particles. The TSM phase diagram has two solid phases and one liquid phase with a solid–solid–liquid triple point which corresponds to the melting curve minimum. The melting curve has both a maximum and a minimum, and the gradient of the melting curve is negative between these extrema. These peculiar melting curve properties and phase diagram are common to alkali metals and some other elements. 相似文献
13.
The transitions between phases of the cell cycle have evolved to be robust and switch-like, which ensures temporal separation of DNA replication, sister chromatid separation, and cell division. Mathematical models describing the biochemical interaction networks of cell cycle regulators attribute these properties to underlying bistable switches, which inherently generate robust, switch-like, and irreversible transitions between states. We have recently presented new mathematical models for two control systems that regulate crucial transitions in the cell cycle: mitotic entry and exit,1 and the mitotic checkpoint.2 Each of the two control systems is characterized by two interlinked bistable switches. In the case of mitotic checkpoint control, these switches are mutually activating, whereas in the case of the mitotic entry/exit network, the switches are mutually inhibiting. In this Perspective we describe the qualitative features of these regulatory motifs and show that having two interlinked bistable mechanisms further enhances robustness and irreversibility. We speculate that these network motifs also underlie other cell cycle transitions and cellular transitions between distinct biochemical states. 相似文献
14.
《Animal biotechnology》2013,24(1):97-112
Developed countries are not immune from serious food-borne diseases, and the source is often the intestine of cattle, sheep and poultry livestock. Outbreaks of Escherichia coli 0157, most recently killing people in Ontario, and of salmonella and shigella food poisoning especially during summer months, remind us of the seriousness of the problem. Thus, there is renewed interest in alternative approaches to antibiotics to control bacterial diseases, both in humans and veterinary medicine.3-4 Consumers are believed to be concerned not only about bacterial pathogens being in meat, but also that residues of antibiotics may also be present. The trend to “natural” farming without exposure to chemicals, pesticides and herbicides could be one reason for increased interest in probiotics for livestock farming. 相似文献
15.
《Fly》2013,7(4):155-159
ABSTRACTAnimals have modular cis-regulatory regions in their genomes, and expression of a single gene is often regulated by multiple enhancers residing in such a region. In the laboratory, and also in natural populations, loss of an enhancer can result in a loss of gene expression. Although only a few examples have been well characterized to date, some studies have suggested that an evolutionary gain of a new enhancer function can establish a new gene expression domain. Our recent study showed that Drosophila guttifera has more enhancers and additional expression domains of the wingless gene during the pupal stage, compared to D. melanogaster, and that these new features appear to have evolved in the ancestral lineage leading to D. guttifera.1 Gain of a new expression domain of a developmental regulatory gene (toolkit gene), such as wingless, can cause co-option of the expression of its downstream genes to the new domain, resulting in duplication of a preexisting structure at this new body position. Recently, with the advancement of evo-devo studies, we have learned that the developmental regulatory systems are strikingly similar across various animal taxa, in spite of the great diversity of the animals' morphology. Even behind “new” traits, co-options of essential developmental genes from known systems are very common. We previously provided concrete evidence of gains of enhancer activities of a developmental regulatory gene underlying gains of new traits.1 Broad occurrence of this scenario is testable and should be validated in the future. 相似文献
16.
《Nucleosides, nucleotides & nucleic acids》2013,32(3):229-241
The Divakar-Reese procedure has been successfully applied for transforming 7-oxo-isothiazolo[4,5-d]pyrimidine C-nucleosides (4a,b, 5a,b, 6a) via 1,2,4-triazol-1-yl intermediates (7a,b, 8a,b) into various 7-substituted C-nucle- osides 15a,b, 16a,b, 17a, 18a, 19a,b, 20a,b; their subsequent deprotection provides novel types of unusual C-glycosides 22b, 23a, 24a,b, 25b, 26b. C-Nucleosides, possessing on its heterocyclic base other than naturally occuring oxo- or amino substituents, are important model compounds for biological or medicinal studies [2a], [2b], [2c], [2d], [2e], [2f], [2g], [2h], [2i] [3a], [3b], [3c], [3d], [3e], [3f], [3g], [3h]. We want to report on the synthesis of novel 7-substituted isothiazolo = [4,5-d]pyrimidine C-nucleosides. As we could show in previous papers [1], [4], there exists a simple approach to the protected C-glycosides 4–6. 相似文献
17.
We investigated the morphology, morphogenesis and small subunit rRNA gene-based phylogeny of three marine urostylids, Uncinata gigantea Bullington, 1940, Holosticha heterofoissneri Hu & Song, 2001, and Holosticha cf. heterofoissneri. The dorsal morphogenesis of Uncinata gigantea shows de novo formation of two groups of anlagen near the marginal rows. Holosticha cf. heterofoissneri demonstrates fragmentation of the first dorsal kinety anlage as in Holosticha heterofoissneri. Our population of H. heterofoissneri corresponds well with previously described populations in terms of its general morphology and ciliary pattern. Uncinata gigantea can be recognized by its large and highly contractile body, yellowish to brownish cell colour, two types of cortical granules, and 20–30 transversely oriented and densely arranged cirri in the left marginal row, which often overlie the buccal vertex. Based on the new data, especially infraciliature, the genus Uncinata is here redefined. Both the morphology and phylogenetic analyses suggest that the genus Uncinata should be classified within the family Urostylidae. In addition, both morphological and morphogenetic data suggest that Holosticha bradburyae Gong et al., 2001 should be transferred to Uncinata as U. bradburyae (Gong et al., 2001) comb. nov., due to its possession of a characteristically prominent beak-like, leftwards curved projection and the developmental mode of the dorsal kineties. This assignment is supported by the phylogenetic analyses, which placed Uncinata gigantea in a clade with U. bradburyae (Gong et al., 2001) comb. nov., and revealed only 1.13% (19 bp) difference in their SSU-rDNA gene sequence. 相似文献
18.
Benjamin Boëns Tan-Sothea Ouk Yves Champavier Rachida Zerrouki 《Nucleosides, nucleotides & nucleic acids》2015,34(7):500-514
This paper describes the synthesis of new click-generated nitrogen mustards and their biological evaluation. By using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, we managed to synthesize eight new nitrogen mustards. This strategy paves the way for the synthesis of a new family of nitrogen mustard, with an important structural variability. Furthermore, we studied the biological activity of synthesized compounds by testing their cytotoxicity on four representative cancer cell lines A431, JURKAT, K562, and U266. One structure, 1-benzyl-4-(N,N-di-2-chloroethylaminomethyl)-1H-[1,2,3]triazole, showed an interesting cytotoxic effect. 相似文献
19.
《Cell Adhesion & Migration》2013,7(4):378-383
Cell migration is a highly integrated, multistep process that plays an important role in physiological and pathological processes. The migrating cell is highly polarized, with complex regulatory pathways that integrate its component processes spatially and temporally.1 The Drosophila tumor suppressor, Lethal (2) giant larvae (Lgl), regulates apical-basal polarity in epithelia and asymmetric cell division.2 But little is known about the role of Lgl in establishing cell polarity in migrating cells. Recently, we showed that the mammalian Lgl1 interacts directly with non-muscle myosin IIA (NMIIA), inhibiting its ability to assemble into filaments in vitro.3 Lgl1 also regulates the cellular localization of NMIIA, the maturation of focal adhesions, and cell migration.3 We further showed that phosphorylation of Lgl1 by aPKCζ prevents its interaction with NMIIA and is important for Lgl1 and acto-NMII cytoskeleton cellular organization.4 Lgl is a critical downstream target of the Par6-aPKC cell polarity complex; we showed that Lgl1 forms two distinct complexes in vivo, Lgl1-NMIIA and Lgl1-Par6-aPKCζ in different cellular compartments.4 We further showed that aPKCζ and NMIIA compete to bind directly to Lgl1 through the same domain. These data provide new insights into the role of Lgl1, NMIIA, and Par6-aPKCζ in establishing front-rear polarity in migrating cells. In this commentary, I discuss the role of Lgl1 in the regulation of the acto-NMII cytoskeleton and its regulation by the Par6-aPKCζ polarity complex, and how Lgl1 activity may contribute to the establishment of front-rear polarity in migrating cells. 相似文献
20.
Disulfide linkage is critical to protein folding and structural stability. The location of disulfide linkages for antibodies is routinely discovered by comparing the chromatograms of the reduced and non-reduced peptide mapping with location identification confirmed by collision-induced dissociation (CID) mass spectrometry (MS)/MS. However, CID product spectra of disulfide-linked peptides can be difficult to interpret, and provide limited information on the backbone region within the disulfide loop. Here, we applied an electron-transfer dissociation (ETD)/CID combined fragmentation method that identifies the disulfide linkage without intensive LC comparison, and yet maps the disulfide location accurately. The native protein samples were digested using trypsin for proteolysis. The method uses RapiGest SF Surfactant and obviates the need for reduction/alkylation and extensive sample manipulation. An aliquot of the digest was loaded onto a C4 analytical column. Peptides were gradient-eluted and analyzed using a Thermo Scientific LTQ Orbitrap Elite mass spectrometer for the ETD-triggered CID MS3 experiment. Survey MS scans were followed by data-dependent scans consisting of ETD MS2 scans on the most intense ion in the survey scan, followed by 5 MS3 CID scans on the 5 most intense ions in the ETD MS2 scan. We were able to identify the disulfide-mediated structural variants A and A/B forms and their corresponding disulfide linkages in an immunoglobulin G2 monoclonal antibody with λ light chain (IgG2λ), where the location of cysteine linkages were unambiguously determined. 相似文献