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231.
Howitt J Lackovic J Low LH Naguib A Macintyre A Goh CP Callaway JK Hammond V Thomas T Dixon M Putz U Silke J Bartlett P Yang B Kumar S Trotman LC Tan SS 《The Journal of cell biology》2012,196(1):29-36
PTEN (phosphatase and tensin homologue deleted on chromosome TEN) is the major negative regulator of phosphatidylinositol 3-kinase signaling and has cell-specific functions including tumor suppression. Nuclear localization of PTEN is vital for tumor suppression; however, outside of cancer, the molecular and physiological events driving PTEN nuclear entry are unknown. In this paper, we demonstrate that cytoplasmic Pten was translocated into the nuclei of neurons after cerebral ischemia in mice. Critically, this transport event was dependent on a surge in the Nedd4 family-interacting protein 1 (Ndfip1), as neurons in Ndfip1-deficient mice failed to import Pten. Ndfip1 binds to Pten, resulting in enhanced ubiquitination by Nedd4 E3 ubiquitin ligases. In vitro, Ndfip1 overexpression increased the rate of Pten nuclear import detected by photobleaching experiments, whereas Ndfip1(-/-) fibroblasts showed negligible transport rates. In vivo, Ndfip1 mutant mice suffered larger infarct sizes associated with suppressed phosphorylated Akt activation. Our findings provide the first physiological example of when and why transient shuttling of nuclear Pten occurs and how this process is critical for neuron survival. 相似文献
232.
Yersinia pestis produces and secretes a toxin named pesticin that kills related bacteria of the same niche. Uptake of the bacteriocin is required for activity in the periplasm leading to hydrolysis of peptidoglycan. To understand the uptake mechanism and to investigate the function of pesticin, we combined crystal structures of the wild type enzyme, active site mutants, and a chimera protein with in vivo and in vitro activity assays. Wild type pesticin comprises an elongated N-terminal translocation domain, the intermediate receptor binding domain, and a C-terminal activity domain with structural analogy to lysozyme homologs. The full-length protein is toxic to bacteria when taken up to the target site via the outer or the inner membrane. Uptake studies of deletion mutants in the translocation domain demonstrate their critical size for import. To further test the plasticity of pesticin during uptake into bacterial cells, the activity domain was replaced by T4 lysozyme. Surprisingly, this replacement resulted in an active chimera protein that is not inhibited by the immunity protein Pim. Activity of pesticin and the chimera protein was blocked through introduction of disulfide bonds, which suggests unfolding as the prerequisite to gain access to the periplasm. Pesticin, a muramidase, was characterized by active site mutations demonstrating a similar but not identical residue pattern in comparison with T4 lysozyme. 相似文献
233.
234.
Gene P. Ables Kryscilla Jian Zhang Yang Silke Vogel Antonio Hernandez-Ono Shuiqing Yu Jason J. Yuen Susan Birtles Linda K. Buckett Andrew V. Turnbull Ira J. Goldberg William S. Blaner Li-Shin Huang Henry N. Ginsberg 《Journal of lipid research》2012,53(11):2364-2379
Acyl CoA:diacylglycerol acyltransferase (DGAT) 1 catalyzes the final step of
triglyceride (TG) synthesis. We show that acute administration of a DGAT1 inhibitor
(DGAT1i) by oral gavage or genetic deletion of intestinal Dgat1
(intestine-Dgat1−/−)
markedly reduced postprandial plasma TG and retinyl ester excursions by inhibiting
chylomicron secretion in mice. Loss of DGAT1 activity did not affect the efficiency
of retinol esterification, but it did reduce TG and retinoid accumulation in the
small intestine. In contrast, inhibition of microsomal triglyceride transfer protein
(MTP) reduced chylomicron secretion after oral fat/retinol loads, but with
accumulation of dietary TG and retinoids in the small intestine. Lack of intestinal
accumulation of TG and retinoids in DGAT1i-treated or
intestine-Dgat1−/− mice
resulted, in part, from delayed gastric emptying associated with increased plasma
levels of glucagon-like peptide (GLP)-1. However, neither bypassing the stomach
through duodenal oil injection nor inhibiting the receptor for GLP-1 normalized
postprandial TG or retinyl esters excursions in the absence of DGAT1 activity. In
summary, intestinal DGAT1 inhibition or deficiency acutely delayed gastric emptying
and inhibited chylomicron secretion; however, the latter occurred when gastric
emptying was normal or when lipid was administered directly into the small intestine.
Long-term hepatic retinoid metabolism was not impacted by DGAT1 inhibition. 相似文献
235.
236.
Reiter S Crescenzi M Galliot B Buzgariu W 《The International journal of developmental biology》2012,56(6-8):593-604
In the freshwater cnidarian polyp Hydra, cell death takes place in multiple contexts. Indeed apoptosis occurs during oogenesis and spermatogenesis, during starvation, and in early head regenerating tips, promoting local compensatory proliferation at the boundary between heterografts. Apoptosis can also be induced upon exposure to pro-apoptotic agents (colchicine, wortmannin), upon heat-shock in the thermosensitive sf-1 mutant, and upon wounding. In all these contexts, the cells that undergo cell death belong predominantly to the interstitial cell lineage, whereas the epithelial cells, which are rather resistant to pro-apoptotic signals, engulf the apoptotic bodies. Beside this clear difference between the interstitial and the epithelial cell lineages, the different interstitial cell derivatives also show noticeable variations in their respective apoptotic sensitivity, with the precursor cells appearing as the most sensitive to pro-apoptotic signals. The apoptotic machinery has been well conserved across evolution. However, its specific role and regulation in each context are not known yet. Tools that help characterize apoptotic activity in Hydra have recently been developed. Among them, the aposensor Apoliner initially designed in Drosophila reliably measures wortmannin-induced apoptotic activity in a biochemical assay. Also, flow cytometry and TUNEL analyses help identify distinctive features between wortmannin-induced and heat-shock induced apoptosis in the sf-1 strain. Thanks to the live imaging tools already available, Hydra now offers a model system with which the functions of the apoptotic machinery to maintain long-term homeostasis, stem cell renewal, germ cell production, active developmental processes and non-self response can be deciphered. 相似文献
237.
Chowdhury MM Dosche C Löhmannsröben HG Leimkühler S 《The Journal of biological chemistry》2012,287(21):17297-17307
We studied two pathways that involve the transfer of persulfide sulfur in humans, molybdenum cofactor biosynthesis and tRNA thiolation. Investigations using human cells showed that the two-domain protein MOCS3 is shared between both pathways. MOCS3 has an N-terminal adenylation domain and a C-terminal rhodanese-like domain. We showed that MOCS3 activates both MOCS2A and URM1 by adenylation and a subsequent sulfur transfer step for the formation of the thiocarboxylate group at the C terminus of each protein. MOCS2A and URM1 are β-grasp fold proteins that contain a highly conserved C-terminal double glycine motif. The role of the terminal glycine of MOCS2A and URM1 was examined for the interaction and the cellular localization with MOCS3. Deletion of the C-terminal glycine of either MOCS2A or URM1 resulted in a loss of interaction with MOCS3. Enhanced cyan fluorescent protein and enhanced yellow fluorescent protein fusions of the proteins were constructed, and the fluorescence resonance energy transfer efficiency was determined by the decrease in the donor lifetime. The cellular localization results showed that extension of the C terminus with an additional glycine of MOCS2A and URM1 altered the localization of MOCS3 from the cytosol to the nucleus. 相似文献
238.
Liebrand TW Smit P Abd-El-Haliem A de Jonge R Cordewener JH America AH Sklenar J Jones AM Robatzek S Thomma BP Tameling WI Joosten MH 《Plant physiology》2012,159(4):1819-1833
Cf proteins are receptor-like proteins (RLPs) that mediate resistance of tomato (Solanum lycopersicum) to the foliar pathogen Cladosporium fulvum. These transmembrane immune receptors, which carry extracellular leucine-rich repeats that are subjected to posttranslational glycosylation, perceive effectors of the pathogen and trigger a defense response that results in plant resistance. To identify proteins required for the functionality of these RLPs, we performed immunopurification of a functional Cf-4-enhanced green fluorescent protein fusion protein transiently expressed in Nicotiana benthamiana, followed by mass spectrometry. The endoplasmic reticulum (ER) heat shock protein70 binding proteins (BiPs) and lectin-type calreticulins (CRTs), which are chaperones involved in ER-quality control, were copurifying with Cf-4-enhanced green fluorescent protein. The tomato and N. benthamiana genomes encode four BiP homologs and silencing experiments revealed that these BiPs are important for overall plant viability. For the three tomato CRTs, virus-induced gene silencing targeting the plant-specific CRT3a gene resulted in a significantly compromised Cf-4-mediated defense response and loss of full resistance to C. fulvum. We show that upon knockdown of CRT3a the Cf-4 protein accumulated, but the pool of Cf-4 protein carrying complex-type N-linked glycans was largely reduced. Together, our study on proteins required for Cf function reveals an important role for the CRT ER chaperone CRT3a in the biogenesis and functionality of this type of RLP involved in plant defense. 相似文献
239.
Silke R. Kirchner Alexander Ohlinger Tom Pfeiffer Alexander S. Urban Fernando D. Stefani Andras Deak Andrey A. Lutich Jochen Feldmann 《Journal of biophotonics》2012,5(1):40-46
Microfluidic jetting is a promising method to produce giant unilamellar phospholipid vesicles for mimicking living cells in biomedical studies. We have investigated the chemical composition of membranes of vesicles prepared using this approach by means of Raman scattering spectroscopy. The membranes of all jetted vesicles are found to contain residuals of the organic solvent decane used in the preparation of the initial planar membrane. The decane inclusions are randomly distributed over the vesicle surface area and vary in thickness from a few to several tens of nanometers. Our findings point out that the membrane properties of jetted vesicles may differ considerably from those of vesicles prepared by other methods and from those of living cells. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
240.
Grünblatt E Geissler J Jacob CP Renner T Müller M Bartl J Gross-Lesch S Riederer P Lesch KP Walitza S Gerlach M Schmitt A 《Attention deficit and hyperactivity disorders》2012,4(2):77-84
Attention-deficit hyperactivity disorder (ADHD) is a common behavioural disorder that affects not only children and adolescents but also adults; however, diagnosis of adult ADHD is difficult because patients seem to have reduced externalized behaviour. ADHD is a multifactorial disorder in which many genes, all with small effects, are thought to cause the disorder in the presence of unfavourable environmental conditions. Therefore, in this pilot study, we explored the expression profile of a list of previously established candidate genes in peripheral blood samples from adult ADHD subjects (n = 108) and compared these results with those of healthy controls (n = 35). We demonstrate that combining the gene expression levels of dopamine transporter (SLC6A3), dopamine D5 receptor, tryptophan hydroxylase-1, and SNAP25 as predictors in a regression model resulted in sensitivity and specificity of over 80 % (ROC: max R(2) = 0.587, AUC = 0.917, P < 0.001, 95 % CI: 0.900-0.985). In conclusion, the combination of these four genes could represent a potential method for estimating risk and could be of diagnostic value for ADHD. Nevertheless, further investigation in a larger independent population including different subtypes of ADHD (inattentive, hyperactive, or combined type) patients is required to obtain more specific sets of biomarkers for each subtype as well as to differentiate between child, adolescent, and adulthood forms. 相似文献