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61.
Zielinski CE Mele F Aschenbrenner D Jarrossay D Ronchi F Gattorno M Monticelli S Lanzavecchia A Sallusto F 《Nature》2012,484(7395):514-518
IL-17-producing CD4+ T helper cells (TH17) have been extensively investigated in mouse models of autoimmunity. However, the requirements for differentiation and the properties of pathogen-induced human TH17 cells remain poorly defined. Using an approach that combines the in vitro priming of naive T cells with the ex vivo analysis of memory T cells, we describe here two types of human TH17 cells with distinct effector function and differentiation requirements. Candida albicans-specific TH17 cells produced IL-17 and IFN-γ, but no IL-10, whereas Staphylococcus aureus-specific TH17 cells produced IL-17 and could produce IL-10 upon restimulation. IL-6, IL-23 and IL-1β contributed to TH17 differentiation induced by both pathogens, but IL-1β was essential in C. albicans-induced TH17 differentiation to counteract the inhibitory activity of IL-12 and to prime IL-17/IFN-γ double-producing cells. In addition, IL-1β inhibited IL-10 production in differentiating and in memory TH17 cells, whereas blockade of IL-1β in vivo led to increased IL-10 production by memory TH17 cells. We also show that, after restimulation, TH17 cells transiently downregulated IL-17 production through a mechanism that involved IL-2-induced activation of STAT5 and decreased expression of ROR-γt. Taken together these findings demonstrate that by eliciting different cytokines C. albicans and S. aureus prime TH17 cells that produce either IFN-γ or IL-10, and identify IL-1β and IL-2 as pro- and anti-inflammatory regulators of TH17 cells both at priming and in the effector phase. 相似文献
62.
Obligate relationships have evolved many times and can be parasitic or mutualistic. Obligate organisms rely on others to survive and thus coevolve with their host or partner. An important but little explored question is whether obligate status is an evolutionarily terminal condition or whether obligate lineages can evolve back to an autonomous lifestyle. The bacterium Myxococcus xanthus survives starvation by the social development of spore-bearing fruiting bodies. Some M. xanthus genotypes defective at fruiting body development in isolation can nonetheless exploit proficient genotypes in chimaeric groups. Here we report an evolutionary transition from obligate dependence on an altruistic host to an autonomous mode of social cooperation. This restoration of social independence was caused by a single mutation of large effect that confers fitness superiority over both ancestral genotypes, including immunity from exploitation by the ancestral cheater. Thus, a temporary state of obligate cheating served as an evolutionary stepping-stone to a novel state of autonomous social dominance. 相似文献
63.
Possemato R Marks KM Shaul YD Pacold ME Kim D Birsoy K Sethumadhavan S Woo HK Jang HG Jha AK Chen WW Barrett FG Stransky N Tsun ZY Cowley GS Barretina J Kalaany NY Hsu PP Ottina K Chan AM Yuan B Garraway LA Root DE Mino-Kenudson M Brachtel EF Driggers EM Sabatini DM 《Nature》2011,476(7360):346-350
Cancer cells adapt their metabolic processes to drive macromolecular biosynthesis for rapid cell growth and proliferation. RNA interference (RNAi)-based loss-of-function screening has proven powerful for the identification of new and interesting cancer targets, and recent studies have used this technology in vivo to identify novel tumour suppressor genes. Here we developed a method for identifying novel cancer targets via negative-selection RNAi screening using a human breast cancer xenograft model at an orthotopic site in the mouse. Using this method, we screened a set of metabolic genes associated with aggressive breast cancer and stemness to identify those required for in vivo tumorigenesis. Among the genes identified, phosphoglycerate dehydrogenase (PHGDH) is in a genomic region of recurrent copy number gain in breast cancer and PHGDH protein levels are elevated in 70% of oestrogen receptor (ER)-negative breast cancers. PHGDH catalyses the first step in the serine biosynthesis pathway, and breast cancer cells with high PHGDH expression have increased serine synthesis flux. Suppression of PHGDH in cell lines with elevated PHGDH expression, but not in those without, causes a strong decrease in cell proliferation and a reduction in serine synthesis. We find that PHGDH suppression does not affect intracellular serine levels, but causes a drop in the levels of α-ketoglutarate, another output of the pathway and a tricarboxylic acid (TCA) cycle intermediate. In cells with high PHGDH expression, the serine synthesis pathway contributes approximately 50% of the total anaplerotic flux of glutamine into the TCA cycle. These results reveal that certain breast cancers are dependent upon increased serine pathway flux caused by PHGDH overexpression and demonstrate the utility of in vivo negative-selection RNAi screens for finding potential anticancer targets. 相似文献
64.
In many organisms, developmentally programmed double-strand breaks (DSBs) formed by the SPO11 transesterase initiate meiotic recombination, which promotes pairing and segregation of homologous chromosomes. Because every chromosome must receive a minimum number of DSBs, attention has focused on factors that support DSB formation. However, improperly repaired DSBs can cause meiotic arrest or mutation; thus, having too many DSBs is probably as deleterious as having too few. Only a small fraction of SPO11 protein ever makes a DSB in yeast or mouse and SPO11 and its accessory factors remain abundant long after most DSB formation ceases, implying the existence of mechanisms that restrain SPO11 activity to limit DSB numbers. Here we report that the number of meiotic DSBs in mouse is controlled by ATM, a kinase activated by DNA damage to trigger checkpoint signalling and promote DSB repair. Levels of SPO11-oligonucleotide complexes, by-products of meiotic DSB formation, are elevated at least tenfold in spermatocytes lacking ATM. Moreover, Atm mutation renders SPO11-oligonucleotide levels sensitive to genetic manipulations that modulate SPO11 protein levels. We propose that ATM restrains SPO11 via a negative feedback loop in which kinase activation by DSBs suppresses further DSB formation. Our findings explain previously puzzling phenotypes of Atm-null mice and provide a molecular basis for the gonadal dysgenesis observed in ataxia telangiectasia, the human syndrome caused by ATM deficiency. 相似文献
65.
Lucia Banci Ivano Bertini Francesca Cantini Simone Ciofi-Baffoni 《Cellular and molecular life sciences : CMLS》2010,67(15):2563-2589
Copper is an essential but potentially harmful trace element required in many enzymatic processes involving redox chemistry.
Cellular copper homeostasis in mammals is predominantly maintained by regulating copper transport through the copper import
CTR proteins and the copper exporters ATP7A and ATP7B. Once copper is imported into the cell, several pathways involving a
number of copper proteins are responsible for trafficking it specifically where it is required for cellular life, thus avoiding
the release of harmful free copper ions. In this study we review recent progress made in understanding the molecular mechanisms
of copper transport in cells by analyzing structural features of copper proteins, their mode of interaction, and their thermodynamic
and kinetic parameters, thus contributing to systems biology of copper within the cell. 相似文献
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67.
Chiara F. Valori Liliana Brambilla Francesca Martorana Daniela Rossi 《Cellular and molecular life sciences : CMLS》2014,71(2):287-297
Despite indisputable progress in the molecular and genetic aspects of amyotrophic lateral sclerosis (ALS), a mechanistic comprehension of the neurodegenerative processes typical of this disorder is still missing and no effective cures to halt the progression of this pathology have yet been developed. Therefore, it seems that a substantial improvement of the outcome of ALS treatments may depend on a better understanding of the molecular mechanisms underlying neuronal pathology and survival as well as on the establishment of novel etiological therapeutic strategies. Noteworthy, a convergence of recent data from multiple studies suggests that, in cellular and animal models of ALS, a complex pathological interplay subsists between motor neurons and their non-neuronal neighbours, particularly glial cells. These observations not only have drawn attention to the physiopathological changes glial cells undergo during ALS progression, but they have moved the focus of the investigations from intrinsic defects and weakening of motor neurons to glia–neuron interactions. In this review, we summarize the growing body of evidence supporting the concept that different glial populations are critically involved in the dreadful chain of events leading to motor neuron sufferance and death in various forms of ALS. The outlined observations strongly suggest that glial cells can be the targets for novel therapeutic interventions in ALS. 相似文献
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69.
Giovanni Di Maira Francesca Brustolon Lorenzo A. Pinna Maria Ruzzene 《Cellular and molecular life sciences : CMLS》2009,66(20):3363-3373
Akt (PKB) is a critical kinase in cell-survival pathways. Its activity depends on the phosphorylation of Thr308 and Ser473,
by PDK1 and mTORC2, respectively. We found that Akt can be further stimulated through phosphorylation of Ser129 by another
kinase, CK2. Here we show that phosphorylation of Akt at Ser129 also facilitates its association with Hsp90 chaperone, thus
preventing Thr308 dephosphorylation. This is supported by the following observations: (1) phospho-Thr308 decreases when Ser129
is mutated to alanine, (2) this decrease is abolished by cell treatment with okadaic acid (to inactivate PP2A) or geldanamycin
(to inactivate Hsp90), (3) phosphorylation of Ser129 neither enhances the activity of PDK1 nor hampers the in vitro activity
of PP2A on Thr308, but increases the Hsp90 association to Akt. These data support the view that the antiapoptotic potential
of CK2 is at least in part mediated by its ability to maintain Akt in its active form. 相似文献
70.
夏季黄连木排放萜烯类化合物浓度日变化及排放速率的研究 总被引:1,自引:0,他引:1
采用流动式采样与气相色谱 质谱联用法研究了意大利撒丁岛Noak’sArk自然生态区主要灌木黄连木 (Pistacialentiscus)萜烯类化合物排放特征、排放速率及其日变化。排放物种包括α 蒎烯、β 蒎烯、桧烯、苎烯、戊花烃、莰烯、β 水芹烯、β 香叶烯、α 松油烯、α 水芹烯和 3 蒈烯 ,以及少量异戊二烯。萜烯类化合物占总排放的 99 4%,异戊二烯仅占 0 6%。在萜烯类化合物中 ,主要排放物为α 蒎烯、β 蒎烯、桧烯和苎烯 ,分别占总排放的 64 5 %、18 4%、6 0 %和 5 9%。萜烯排放速率随温度的升高而增加 ,呈指数相关。在标准条件下 ( 30 3K) ,黄连木树种的排放速率为 2 72±0 72 μg g·h。黄连木排放速率公式中 β值为 0 12 8K-1,与文献值 0 0 5 7~ 0 144K-1相一致。 相似文献