共查询到20条相似文献,搜索用时 46 毫秒
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Michelle D. Leach David A. Stead Evelyn Argo Donna M. MacCallum Alistair J. P. Brown 《Molecular microbiology》2012,84(3):594-594
How cells co‐ordinate size with growth and development is a major, unresolved question in cell biology. In previous work we identified the glucosyltransferase UgtP as a division inhibitor responsible for increasing the size of Bacillus subtilis cells under nutrient‐rich conditions. In nutrient‐rich medium, UgtP is distributed more or less uniformly throughout the cytoplasm and concentrated at the cell poles and/or the cytokinetic ring. Under these conditions, UgtP interacts directly with FtsZ to inhibit division and increase cell size. Conversely, under nutrient‐poor conditions, UgtP is sequestered away from FtsZ in punctate foci, and division proceeds unimpeded resulting in a reduction in average cell size. Here we report that nutrient‐dependent changes in UgtP's oligomerization potential serve as a molecular rheostat to precisely co‐ordinate B. subtilis cell size with nutrient availability. Our data indicate UgtP interacts with itself and the essential cell division protein FtsZ in a high‐affinity manner influenced in part by UDP glucose, an intracellular proxy for nutrient availability. These findings support a model in which UDP‐glc‐dependent changes in UgtP's oligomerization potential shift the equilibrium between UgtP?UgtP and UgtP?FtsZ, fine‐tuning the amount of FtsZ available for assembly into the cytokinetic ring and with it cell size. 相似文献
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Juan C. Alonso Gerhild Lüder Thomas A. Trautner 《Molecular & general genetics : MGG》1992,236(1):60-64
Summary Ribosomal protein synthesis is regulated by controlling the fraction of mRNA associated with polysomes. It is known that this value changes in different developmental stages during Xenopus embryogenesis or, more generally, with changing cell growth conditions. We present here an analysis of the proportion of mRNA loaded on polysomes, carried out with probes for five different ribosomal proteins on several batches of Xenopus embryos obtained from different individuals. The results obtained indicate the existence of probe-dependent and individual differences, which reflect genetic variations in the cis- and trans-acting regulatory elements responsible for translational regulation. The fraction of ribosomal protein mRNA loaded onto polysomes can be used as an index of an individual's capacity for ribosome production. 相似文献
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Xiongfeng Dai Mya Warren Daniel Sévin Yi‐Ping Wang Terence Hwa 《Molecular systems biology》2015,11(10)
Understanding how the homeostasis of cellular size and composition is accomplished by different organisms is an outstanding challenge in biology. For exponentially growing Escherichia coli cells, it is long known that the size of cells exhibits a strong positive relation with their growth rates in different nutrient conditions. Here, we characterized cell sizes in a set of orthogonal growth limitations. We report that cell size and mass exhibit positive or negative dependences with growth rate depending on the growth limitation applied. In particular, synthesizing large amounts of “useless” proteins led to an inversion of the canonical, positive relation, with slow growing cells enlarged 7‐ to 8‐fold compared to cells growing at similar rates under nutrient limitation. Strikingly, this increase in cell size was accompanied by a 3‐ to 4‐fold increase in cellular DNA content at slow growth, reaching up to an amount equivalent to ~8 chromosomes per cell. Despite drastic changes in cell mass and macromolecular composition, cellular dry mass density remained constant. Our findings reveal an important role of protein synthesis in cell division control. 相似文献
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AtLa1 protein initiates IRES‐dependent translation of WUSCHEL mRNA and regulates the stem cell homeostasis of Arabidopsis in response to environmental hazards
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Yuchao Cui Shaofei Rao Beibei Chang Xiaoshuang Wang Kaidian Zhang Xueliang Hou Xueyi Zhu Haijun Wu Zhaoxia Tian Zhong Zhao Chengwei Yang Tao Huang 《Plant, cell & environment》2015,38(10):2098-2114
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Cell suspension cultures of parsley (Petroselinum crispum) exhibited an altered pattern of protein synthesis after transfer from complete growth medium to water or medium containing no macronutrients. Similar changes occurred when cultures were grown in the original medium until the nutrients were depleted. The effect was reversible upon transfer to fresh medium and was not observed during regular subculturing of the cells. While total protein synthesis decreased sharply after nutrient depletion, the synthesis of a few characteristic proteins (starvation-related proteins, STPs) increased strongly. The protein labeled at highest rates with [35S]methionine in vivo (STP 62) had an apparent molecular weight of about 62000 and a pI of about 6.3. Although its increased rate of synthesis was therefore easily detected by labeling in vivo, translation of mRNA in vitro did not give comparable results. Thus, regulatory control may be exerted mainly at the level of translation. Synthesis of STP ceased rapidly when heat shock (37° C) was applied under conditions of nutrient depletion, whereas heat-shock proteins were strongly induced.Abbreviations HSP
heat-shock protein
- STP
starvation-related protein 相似文献
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The coccolithophores Emiliania and Pleurochrysis demonstrate increased coccolith production when growth is reduced by nitrate or phosphate limitation. The function of enhanced coccolith production under these conditions and its regulation have not been resolved. Studies at the molecular level are ideally suited to determine the exact relationship between calcification and other cellular functions. In a previous study we provided evidence for the presence of a vacuolar H+‐ATPase on coccolith vesicle membranes of P. carterae. These trans‐Golgi–derived vesicles are the sites of coccolith production, with each vesicle containing one coccolith. In this study, expression of the vap gene, encoding subunit c of the vacuolar H+‐ATPase, was investigated. Our objective was to explore potential relationships between vap expression, nutrient‐dependent growth, and calcification. Specifically, we monitored vap expression relative to two genes, fcp and pcna, whose expression was previously shown to vary with growth conditions; fcp encodes a fucoxanthin chl a/c‐binding protein, and pcna encodes the proliferating cell nuclear antigen. Relative to the expression of pcna and fcp, vap expression was highest at nutrient concentrations where growth curves and chl a patterns indicated arrest of cell division. Our results indicate that the level of vap expression does not decrease when cell growth diminishes. 相似文献
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Sang Kwang Lee Yongtae Kim Sung‐Soo Kim Jeong Hwa Lee Kun Cho Sang Sook Lee Zee‐Won Lee Kyung‐Hoon Kwon Young Hye Kim Haeyoung Suh‐Kim Jong Shin Yoo Young Mok Park 《Proteomics》2009,9(18):4389-4405
Mesenchymal stem cells (MSCs) are multipotent cells, which have the capability to differentiate into various mesenchymal tissues such as bone, cartilage, fat, tendon, muscle, and marrow stroma. However, they lose the capability of multi‐lineage differentiation after several passages. It is known that basic fibroblast growth factor (bFGF) increases growth rate, differentiation potential, and morphological changes of MSCs in vitro. In this report, we have used 2‐DE coupled to MS to identify differentially expressed proteins at the cell membrane level in MSCs growing in bFGF containing medium. The cell surface proteins isolated by the biotin–avidin affinity column were separated by 2‐DE in triplicate experiments. A total of 15 differentially expressed proteins were identified by quadrupole‐time of flight tandem MS. Nine of the proteins were upregulated and six proteins were downregulated in the MSCs cultured with bFGF containing medium. The expression level of three actin‐related proteins, F‐actin‐capping protein subunit alpha‐1, actin‐related protein 2/3 complex subunit 2, and myosin regulatory light chain 2, was confirmed by Western blot analysis. The results indicate that the expression levels of F‐actin‐capping protein subunit alpha‐1, actin‐related protein 2/3 complex subunit 2, and myosin regulatory light chain 2 are important in bFGF‐induced morphological change of MSCs. 相似文献
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Laura M Zidek Tobias Ackermann Götz Hartleben Sabrina Eichwald Gertrud Kortman Michael Kiehntopf Achim Leutz Nahum Sonenberg Zhao‐Qi Wang Julia von Maltzahn Cornelis F Calkhoven 《EMBO reports》2015,16(8):1022-1036
The mammalian target of rapamycin complex 1 (mTORC1) is a central regulator of physiological adaptations in response to changes in nutrient supply. Major downstream targets of mTORC1 signalling are the mRNA translation regulators p70 ribosomal protein S6 kinase 1 (S6K1p70) and the 4E‐binding proteins (4E‐BPs). However, little is known about vertebrate mRNAs that are specifically controlled by mTORC1 signalling and are engaged in regulating mTORC1‐associated physiology. Here, we show that translation of the CCAAT/enhancer binding protein beta (C/EBPβ) mRNA into the C/EBPβ‐LIP isoform is suppressed in response to mTORC1 inhibition either through pharmacological treatment or through calorie restriction. Our data indicate that the function of 4E‐BPs is required for suppression of LIP. Intriguingly, mice lacking the cis‐regulatory upstream open reading frame (uORF) in the C/EBPβ‐mRNA, which is required for mTORC1‐stimulated translation into C/EBPβ‐LIP, display an improved metabolic phenotype with features also found under calorie restriction. Thus, our data suggest that translational adjustment of C/EBPβ‐isoform expression is one of the key processes that direct metabolic adaptation in response to changes in mTORC1 activity. 相似文献
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Diatoms are the main primary producers in the Southern Ocean, governing the major nutrient cycles. Fragilariopsis kerguelensis (O’Meara) Hust. is the most abundant diatom species in the Southern Ocean and its paleo‐oceanographic record is frequently used to reconstruct the past position and nutrient characteristics of the Antarctic polar front. Here we report on the responses of F. kerguelensis on prolonged exposure to a range of iron concentrations, allowing a characterization of morphological and nutrient‐depletion changes in relation to iron status. Under iron limitation, F. kerguelensis grew slower, cells became smaller, chains became shorter, and the nutrient‐depletion ratios changed. Prolonged exposure to iron limitation caused F. kerguelensis to decrease its surface area and volume 2‐fold, and to increase its surface‐to‐volume ratio by 25%. With the decrease in growth rates, silicon (Si) and phosphorus (P) depletion per cell remained fairly constant, but when normalized per surface area (Si) or per cell volume (P), depletion increased. In contrast, nitrogen (N) depletion per cell decreased significantly together with the decrease in growth rates but was constant when normalized per cell volume. The different response in Si, P, and N depletion resulted in changes in the nutrient‐depletion ratios, most notably in the Si:N ratio, which significantly increased, and in the N:P ratio, which significantly decreased with decreasing growth rates. It is concluded that under iron limitation, variation in cell size and/or nutrient depletion ultimately can cause changes in oceanic biogeochemical nutrient cycles. It enables the use of cell size of F. kerguelensis as a paleo‐oceanographic proxy. 相似文献
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Fatemeh Zandi Naser Eslami Masoomeh Soheili Ahmad Fayaz Alireza Gholami Behrouz Vaziri Dr. 《Proteomics》2009,9(9):2399-2407
Rabies is a neurotropic virus that causes a life threatening acute viral encephalitis. The complex relationship of rabies virus (RV) with the host leads to its replication and spreading toward the neural network, where viral pathogenic effects appeared as neuronal dysfunction. In order to better understand the molecular basis of this relationship, a proteomics study on baby hamster kidney cells infected with challenge virus standard strain of RV was performed. This cell line is an in vitro model for rabies infection and is commonly used for viral seed preparation. The direct effect of the virus on cellular protein machinery was investigated by 2‐DE proteome mapping of infected versus control cells followed by LC‐MS/MS identification. This analysis revealed significant changes in expression of 14 proteins, seven of these proteins were viral and the remaining were host proteins with different known functions: cytoskeletal (capping protein, vimentin), anti‐oxidative stress (superoxide dismutase), regulatory (Stathmin), and protein synthesis (P0). Despite of limited changes appeared upon rabies infection, they present a set of interesting biochemical pathways for further investigation on viral‐host interaction. 相似文献
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Increased RNA polymerase availability directs resources towards growth at the expense of maintenance
Bertil Gummesson Lisa U Magnusson Kristian Kvint Örjan Persson Anne Farewell Thomas Nyström 《The EMBO journal》2009,28(15):2209-2219
Nutritionally induced changes in RNA polymerase availability have been hypothesized to be an evolutionary primeval mechanism for regulation of gene expression and several contrasting models have been proposed to explain how such ‘passive’ regulation might occur. We demonstrate here that ectopically elevating Escherichia coli RNA polymerase (Eσ70) levels causes an increased expression and promoter occupancy of ribosomal genes at the expense of stress‐defense genes and amino acid biosynthetic operons. Phenotypically, cells overproducing Eσ70 favours growth and reproduction at the expense of motility and damage protection; a response reminiscent of cells with no or diminished levels of the alarmone guanosine tetraphosphate (ppGpp). Consistently, we show that cells lacking ppGpp displayed markedly elevated levels of free Eσ70 compared with wild‐type cells and that the repression of ribosomal RNA expression and reduced growth rate of mutants with constitutively elevated levels of ppGpp can be suppressed by overproducing Eσ70. We conclude that ppGpp modulates the levels of free Eσ70 and that this is an integral part of the alarmone's means of regulating a trade‐off between growth and maintenance. 相似文献
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Jee‐Youn Kim Young‐Eun Cho Yong‐Min An Sang‐Hoon Kim Yong‐Gwan Lee Jae‐Hoon Park Sun Lee 《Journal of cellular and molecular medicine》2015,19(6):1245-1252
Nucleophosmin (NPM)/B23, a multifunctional nucleolar phosphoprotein, plays an important role in ribosome biogenesis, cell cycle regulation, apoptosis and cancer pathogenesis. The role of NPM in cells is determined by several factors, including total expression level, oligomerization or phosphorylation status, and subcellular localization. In the nucleolus, NPM participates in rRNA maturation to enhance ribosomal biogenesis. Consistent with this finding, NPM expression is increased in rapidly proliferating cells and many types of human cancers. In response to ribosomal stress, NPM is redistributed to the nucleoplasm, where it inactivates mouse double minute 2 homologue to stabilize p53 and inhibit cell cycle progression. These observations indicate that nucleolus‐nucleoplasmic mobilization of NPM is one of the key molecular mechanisms that determine the role of NPM within the cell. However, the regulatory molecule(s) that control(s) NPM stability and subcellular localization, crucial to the pluripotency of intercellular NPM, remain(s) unidentified. In this study, we showed that nucleolar protein GLTSCR2/Pict‐1 induced nucleoplasmic translocation and enhanced the degradation of NPM via the proteasomal polyubiquitination pathway. In addition, we showed that GLTSCR2 expression decreased the transforming activity of cells mediated by NPM and that the expression of NPM is reciprocally related to that of GLTSCR2 in cervical cancer tissue. In this study, we demonstrated that GLTSCR2 is an upstream negative regulator of NPM. 相似文献
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Christian Hertig Michael Melzer Twan Rutten Stephan Erbe Gtz Hensel Jochen Kumlehn Winfriede Weschke Hans Weber Johannes Thiel 《The Plant journal : for cell and molecular biology》2020,103(5):1869-1884
Cereal endosperm represents the most important source of the world’s food; nevertheless, the molecular mechanisms underlying cell and tissue differentiation in cereal grains remain poorly understood. Endosperm cellularization commences at the maternal–filial intersection of grains and generates endosperm transfer cells (ETCs), a cell type with a prominent anatomy optimized for efficient nutrient transport. Barley HISTIDINE KINASE1 (HvHK1) was identified as a receptor component with spatially restricted expression in the syncytial endosperm where ETCs emerge. Here, we demonstrate its function in ETC fate acquisition using RNA interference‐mediated downregulation of HvHK1. Repression of HvHK1 impairs cell specification in the central ETC region and the development of transfer cell morphology, and consecutively defects differentiation of adjacent endosperm tissues. Coinciding with reduced expression of HvHK1, disturbed cell plate formation and fusion were observed at the initiation of endosperm cellularization, revealing that HvHK1 triggers initial cytokinesis of ETCs. Cell‐type‐specific RNA sequencing confirmed loss of transfer cell identity, compromised cell wall biogenesis and reduced transport capacities in aberrant cells and elucidated two‐component signaling and hormone pathways that are mediated by HvHK1. Gene regulatory network modeling was used to specify the direct targets of HvHK1; this predicted non‐canonical auxin signaling elements as the main regulatory links governing cellularization of ETCs, potentially through interaction with type‐B response regulators. This work provides clues to previously unknown molecular mechanisms directing ETC specification, a process with fundamental impact on grain yield in cereals. 相似文献