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91.
Vitlin A Weiss C Demishtein-Zohary K Rasouly A Levin D Pisanty-Farchi O Breiman A Azem A 《Plant molecular biology》2011,77(1-2):105-115
The involvement of type I chaperonins in bacterial and organellar protein folding has been well-documented. In E. coli and mitochondria, these ubiquitous and highly conserved proteins form chaperonin oligomers of identical 60 kDa subunits (cpn60), while in chloroplasts, two distinct cpn60 α and β subunit types co-exist together. The primary sequence of α and β subunits is ~50% identical, similar to their respective homologies to the bacterial GroEL. Moreover, the A. thaliana genome contains two α and four β genes. The functional significance of this variability in plant chaperonin proteins has not yet been elucidated. In order to gain insight into the functional variety of the chloroplast chaperonin family members, we reconstituted β homo-oligomers from A. thaliana following their expression in bacteria and subjected them to a structure-function analysis. Our results show for the first time, that A. thaliana β homo-oligomers can function in vitro with authentic chloroplast co-chaperonins (ch-cpn10 and ch-cpn20). We also show that oligomers made up of different β subunit types have unique properties and different preferences for co-chaperonin partners. We propose that chloroplasts may contain active β homo-oligomers in addition to hetero-oligomers, possibly reflecting a variety of cellular roles. 相似文献
92.
93.
Either protective or toxic effects of cannabinoids on cell survival have been reported extensively in the literature; however,
the factors that determine the direction of the effect are still obscured. In this study we have used the neuroblastoma cell
line N18TG2 that expresses CB1 cannabinoid receptors to investigate several factors that may determine the consequences of
exposure to cannabinoid agonists. Cells that were grown under optimal, stressful, or differentiating conditions were exposed
to cannabinoid agonists and then assayed for cell viability by measuring MTT, LDH, and caspase-3 activity. Various cannabinoid
agonists (CP 55,940, ∆9-THC, HU-210, and WIN 55,212-2) failed to affect cell viability when the cells were grown under optimal
conditions. On the other hand, the same agonists significantly reduced cell viability when the cells were grown under stressful
conditions (glucose- and serum-free medium), while enhancing the viability of cells grown in differentiation medium (0.5%
serum and 1.5% DMSO). The toxic/protective profile was not dependent on the type or the concentration of the cannabinoid agonist
that was applied. The cannabinoid agonist CP 55,940 similarly affected the non-neuronal HEK-293 cells that were grown under
stressful conditions only when they expressed CB1 receptors. Our results shed light on the conflicting reports regarding the
protective or toxic effects of cannabinoids in vitro and indicate that cannabinoids may activate different intracellular signaling
mechanisms, depending on the state of the cell, thus leading to different physiological consequences. 相似文献
94.
95.
Amiel A. Dror Danielle R. Lenz Shaked Shivatzki Keren Cohen Osnat Ashur-Fabian Karen B. Avraham 《Mammalian genome》2014,25(7-8):304-316
Thyroid hormone is essential for inner ear development and is required for auditory system maturation. Human mutations in SLC26A4 lead to a syndromic form of deafness with enlargement of the thyroid gland (Pendred syndrome) and non-syndromic deafness (DFNB4). We describe mice with an Slc26a4 mutation, Slc26a4 loop/loop , which are profoundly deaf but show a normal sized thyroid gland, mimicking non-syndromic clinical signs. Histological analysis of the thyroid gland revealed defective morphology, with a majority of atrophic microfollicles, while measurable thyroid hormone in blood serum was within the normal range. Characterization of the inner ear showed a spectrum of morphological and molecular defects consistent with inner ear pathology, as seen in hypothyroidism or disrupted thyroid hormone action. The pathological inner ear hallmarks included thicker tectorial membrane with reduced β-tectorin protein expression, the absence of BK channel expression of inner hair cells, and reduced inner ear bone calcification. Our study demonstrates that deafness in Slc26a4 loop/loop mice correlates with thyroid pathology, postulating that sub-clinical thyroid morphological defects may be present in some DFNB4 individuals with a normal sized thyroid gland. We propose that insufficient availability of thyroid hormone during inner ear development plays an important role in the mechanism underlying deafness as a result of SLC26A4 mutations. 相似文献
96.
Gal Wittenberg Alexander Levitan Tamir Klein Inbal Dangoor Nir Keren Avihai Danon 《The Plant journal : for cell and molecular biology》2014,78(6):1003-1013
A chloroplast protein disulfide isomerase (PDI) was previously proposed to regulate translation of the unicellular green alga Chlamydomonas reinhardtii chloroplast psbA mRNA, encoding the D1 protein, in response to light. Here we show that AtPDI6, one of 13 Arabidopsis thaliana PDI genes, also plays a role in the chloroplast. We found that AtPDI6 is targeted and localized to the chloroplast. Interestingly, AtPDI6 knockdown plants displayed higher resistance to photoinhibition than wild‐type plants when exposed to a tenfold increase in light intensity. The AtPDI6 knockdown plants also displayed a higher rate of D1 synthesis under a similar light intensity. The increased resistance to photoinhibition may not be rationalized by changes in antenna or non‐photochemical quenching. Thus, the increased D1 synthesis rate, which may result in a larger proportion of active D1 under light stress, may led to the decrease in photoinhibition. These results suggest that, although the D1 synthesis rates observed in wild‐type plants under high light intensities are elevated, repair can potentially occur faster. The findings implicate AtPDI6 as an attenuator of D1 synthesis, modulating photoinhibition in a light‐regulated manner. 相似文献
97.
Sigal Cohen Michal Zmudjak Catherine Colas des Francs‐Small Sunita Malik Felix Shaya Ido Keren Eduard Belausov Yair Many Gregory G. Brown Ian Small Oren Ostersetzer‐Biran 《The Plant journal : for cell and molecular biology》2014,78(2):253-268
Group II introns are large catalytic RNAs that are found in bacteria and organellar genomes of lower eukaryotes, but are particularly prevalent within mitochondria in plants, where they are present in many critical genes. The excision of plant mitochondrial introns is essential for respiratory functions, and is facilitated in vivo by various protein cofactors. Typical group II introns are classified as mobile genetic elements, consisting of the self‐splicing ribozyme and its own intron‐encoded maturase protein. A hallmark of maturases is that they are intron‐specific, acting as cofactors that bind their intron‐containing pre‐RNAs to facilitate splicing. However, the degeneracy of the mitochondrial introns in plants and the absence of cognate intron‐encoded maturase open reading frames suggest that their splicing in vivo is assisted by ‘trans’‐acting protein factors. Interestingly, angiosperms harbor several nuclear‐encoded maturase‐related (nMat) genes that contain N‐terminal mitochondrial localization signals. Recently, we established the roles of two of these paralogs in Arabidopsis, nMAT1 and nMAT2, in the splicing of mitochondrial introns. Here we show that nMAT4 (At1g74350) is required for RNA processing and maturation of nad1 introns 1, 3 and 4 in Arabidopsis mitochondria. Seed germination, seedling establishment and development are strongly affected in homozygous nmat4 mutants, which also show modified respiration phenotypes that are tightly associated with complex I defects. 相似文献
98.
A computational study of the Warburg effect identifies metabolic targets inhibiting
cancer migration
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99.
Michael B. Cook Douglas A. Corley Liam J. Murray Linda M. Liao Farin Kamangar Weimin Ye Marilie D. Gammon Harvey A. Risch Alan G. Casson Neal D. Freedman Wong-Ho Chow Anna H. Wu Leslie Bernstein Olof Nyrén Nirmala Pandeya David C. Whiteman Thomas L. Vaughan 《PloS one》2014,9(7)
Background
Previous studies have evidenced an association between gastroesophageal reflux and esophageal adenocarcinoma (EA). It is unknown to what extent these associations vary by population, age, sex, body mass index, and cigarette smoking, or whether duration and frequency of symptoms interact in predicting risk. The Barrett’s and Esophageal Adenocarcinoma Consortium (BEACON) allowed an in-depth assessment of these issues.Methods
Detailed information on heartburn and regurgitation symptoms and covariates were available from five BEACON case-control studies of EA and esophagogastric junction adenocarcinoma (EGJA). We conducted single-study multivariable logistic regressions followed by random-effects meta-analysis. Stratified analyses, meta-regressions, and sensitivity analyses were also conducted.Results
Five studies provided 1,128 EA cases, 1,229 EGJA cases, and 4,057 controls for analysis. All summary estimates indicated positive, significant associations between heartburn/regurgitation symptoms and EA. Increasing heartburn duration was associated with increasing EA risk; odds ratios were 2.80, 3.85, and 6.24 for symptom durations of <10 years, 10 to <20 years, and ≥20 years. Associations with EGJA were slighter weaker, but still statistically significant for those with the highest exposure. Both frequency and duration of heartburn/regurgitation symptoms were independently associated with higher risk. We observed similar strengths of associations when stratified by age, sex, cigarette smoking, and body mass index.Conclusions
This analysis indicates that the association between heartburn/regurgitation symptoms and EA is strong, increases with increased duration and/or frequency, and is consistent across major risk factors. Weaker associations for EGJA suggest that this cancer site has a dissimilar pathogenesis or represents a mixed population of patients. 相似文献100.
Zehava Grossman Jonathan M. Schapiro Itzchak Levy Daniel Elbirt Michal Chowers Klaris Riesenberg Karen Olstein-Pops Eduardo Shahar Valery Istomin Ilan Asher Bat-Sheva Gottessman Yonat Shemer Hila Elinav Gamal Hassoun Shira Rosenberg Diana Averbuch Keren Machleb-Guri Zipi Kra-Oz Sara Radian-Sade Hagit Rudich Daniela Ram Shlomo Maayan Nancy Agmon-Levin Zev Sthoeger 《PloS one》2014,9(1)