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291.
Dynamic protein methylation in chromatin biology 总被引:1,自引:1,他引:0
292.
G. M. C. Janssen P. Schwertman T. A. T. Wanga R. S. Jahangir Tafrechi P. J. A. van den Broek A. K. Raap 《Cellular and molecular life sciences : CMLS》2009,66(4):721-730
Cytoplasmic translation is under sophisticated control but how cells adapt its rate to constitutive loss of mitochondrial
oxidative phosphorylation is unknown. Here we show that translation is repressed in cells with the pathogenic A3243G mtDNA
mutation or in mtDNA-less ρ0 cells by at least two distinct pathways, one transiently targeting elongation factor eEF-2 and the other initiation factor
eIF-2α constitutively. Under conditions of exponential cell growth and mammalian target of rapamycin (mTOR) activation, eEF-2
becomes transiently phosphorylated by an AMP-activated protein kinase (AMPK)-dependent pathway, especially high in mutant
cells. Independent of AMPK and mTOR, eIF-2α is constitutively phosphorylated in mutant cells, likely a signature of endoplasmic
reticulum (ER)-stress response induced by the loss of oxidative phosphorylation. While the AMPK/eEF-2K/eEF-2 pathway appears
to function in adaptation to physiological fluctuations in ATP levels in the mutant cells, the ER stress signified by constitutive
protein synthesis inhibition through eIF-2α-mediated repression of translation initiation may have pathobiochemical consequences.
Received 29 October 2008; received after revision 11 December 2008; accepted 16 December 2008 相似文献
293.
Ronda Bransteitter Courtney Prochnow Xiaojiang S. Chen 《Cellular and molecular life sciences : CMLS》2009,66(19):3137-3147
The apolipoprotein B mRNA-editing enzyme catalytic polypeptide (APOBEC) family of cytidine deaminases has emerged as an intensively
studied field as a result of their important biological functions. These enzymes are involved in lipid metabolism, antibody
diversification, and the inhibition of retrotransposons, retroviruses, and some DNA viruses. The APOBEC proteins function
in these roles by deaminating single-stranded (ss) DNA or RNA. There are two high-resolution crystal structures available
for the APOBEC family, Apo2 and the C-terminal catalytic domain (CD2) of Apo3G or Apo3G-CD2 [Holden et al. (Nature 456:121–124,
2008); Prochnow et al. (Nature 445:447–451, 2007)]. Additionally, the structure of Apo3G-CD2 has also been determined using
NMR [Chen et al. (Nature 452:116–119, 2008); Furukawa et al. (EMBO J 28:440–451, 2009); Harjes et al. (J Mol Biol, 2009)].
A detailed structural analysis of the APOBEC proteins and a comparison to other zinc-coordinating deaminases can facilitate
our understanding of how APOBEC proteins bind nucleic acids, recognize substrates, and form oligomers. Here, we review the
recent development of structural and functional studies that apply to Apo3G as well as the APOBEC deaminase family. 相似文献
294.
A. Shukla P. Chaurasia S. R. Bhaumik 《Cellular and molecular life sciences : CMLS》2009,66(8):1419-1433
Methylation of lysine residues of histones is associated with functionally distinct regions of chromatin, and, therefore,
is an important epigenetic mark. Over the past few years, several enzymes that catalyze this covalent modification on different
lysine residues of histones have been discovered. Intriguingly, histone lysine methylation has also been shown to be cross-regulated
by histone ubiquitination or the enzymes that catalyze this modification. These covalent modifications and their cross-talks
play important roles in regulation of gene expression, heterochromatin formation, genome stability, and cancer. Thus, there
has been a very rapid progress within past several years towards elucidating the molecular basis of histone lysine methylation
and ubiquitination, and their aberrations in human diseases. Here, we discuss these covalent modifications with their cross-regulation
and roles in controlling gene expression and stability.
Received 24 September 2008; received after revision 21 November 2008; accepted 28 November 2008 相似文献
295.
S. Kjellev 《Cellular and molecular life sciences : CMLS》2009,66(8):1350-1369
The trefoil factor family (TFF) comprises a group of small peptides which are highly expressed in tissues containing mucus-producing
cells – especially in the mucosa lining the gastrointestinal tract. The peptides seem crucial for epithelial restitution and
may work via other pathways than the conventional factors involved in restitution. In vitro studies have shown that the TFFs promote restitution using multiple mechanisms. The peptides also have other functionalities
including interactions with the immune system. Moreover, therapeutic effects of the TFFs have been shown in several animal
models of gastrointestinal damage. Still it is not clear which of their in vitro properties are involved in the in vivo mode of action. This review describes the TFF family with emphasis on their biological properties and involvement in mucosal
protection and repair.
Received 10 October 2008; received after revision 07 November 2008; accepted 10 November 2008 相似文献
296.
297.
In 1985, more than thirty geomorphologists, planetary scientists, and remote sensing specialists gathered at a conference center in Oracle, Arizona, to discuss an emerging area of research that they called “mega-geomorphology.” Building on a conference of the same name held in London in 1981, they argued that new techniques of remote sensing and insights emerging from the study of extraterrestrial planets had created opportunities for geomorphology to broaden its spatial and temporal scope. This new approach was, however, neither unproblematic nor uncontested. In the discussions around mega-geomorphology that took place in the mid-1980s, the perceived conflict between the use of remote-sensing techniques to observe phenomena on vast spatial scales, on one hand, and the disciplinary centrality of fieldwork and field experience to geomorphology, on the other, was a recurrent theme. In response, mega-geomorphologists attempted to re-situate fieldwork and re-narrate disciplinary histories in such a way as to make remote sensing and planetary science not only compatible with geomorphological traditions but also means of revitalizing them. Only partially successful, these attempts reveal that the process of adopting a planetary perspective in geomorphology, as in other earth sciences, was neither straightforward nor inevitable. They also show how the field and fieldwork could remain central to geomorphology while also being extensively revised in light of new technical possibilities and theoretical frameworks. 相似文献
298.
299.
Juliana L. Segadilha Priscila S. Nascimento Fábio M. Mauro Cristiana S. Serejo Taiara R. Ramos Irene A. Cardoso 《Journal of Natural History》2018,52(1-2):1-11
A total of 3109 crustaceans belonging to 50 taxa distributed in 42 families were found in 117 analysed stomachs of flying gurnard (Dactylopterus volitans). Samples were obtained in April 2008 by the R/V Gyre using a bottom trawl towed in 12 stations at 14–100 m depth on the continental shelf of the Campos Basin, Brazil. The carcinofauna was analysed and the order Calanoida (Copepoda) found to be the most important item in terms of relative abundance and frequency of occurrence, followed by the order Amphipoda (Peracarida), the infraorder Brachyura (Decapoda), the order Stomatopoda and the subclass Myodocopa (Ostracoda). In the order Calanoida, the species Pontellopsis cf. villosa (Pontellidae) represented 98.04% of total crustacean abundance. The diet of Dactylopterus volitans varied according to fish size, with higher diversity of Crustacea at smaller size classes, decreasing in larger fishes. A similar pattern regarding depth was obtained, with greater diversity of taxa in gurnard stomachs caught at shallower depths. Flying gurnard is considered a generalized carnivore of invertebrates, eating mobile macrobenthic organisms, such as crustaceans, and its diet varies with its life stage, without any specific group as its main food source. 相似文献