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Disentangling the Microphysical Effects of Fire Particles on Convective Clouds Through A Case Study 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2020, 125 (12)
作者:  Takeishi, Azusa;  Storelvmo, Trude;  Fierce, Laura
收藏  |  浏览/下载：31/0  |  提交时间：2020/08/18
aerosol-cloud interaction  aerosol activation  WRF-CHEM  
Insights into the assembly and activation of the microtubule nucleator gamma-TuRC 期刊论文
NATURE, 2020, 578 (7795) : 467-+
作者:  Cyranoski, David
收藏  |  浏览/下载：34/0  |  提交时间：2020/07/03

Microtubules are dynamic polymers of alpha- and beta-tubulin and have crucial roles in cell signalling, cell migration, intracellular transport and chromosome segregation(1). They assemble de novo from alpha beta-tubulin dimers in an essential process termed microtubule nucleation. Complexes that contain the protein gamma-tubulin serve as structural templates for the microtubule nucleation reaction(2). In vertebrates, microtubules are nucleated by the 2.2-megadalton gamma-tubulin ring complex (gamma-TuRC), which comprises gamma-tubulin, five related gamma-tubulin complex proteins (GCP2-GCP6) and additional factors(3). GCP6 is unique among the GCP proteins because it carries an extended insertion domain of unknown function. Our understanding of microtubule formation in cells and tissues is limited by a lack of high-resolution structural information on the gamma-TuRC. Here we present the cryo-electron microscopy structure of gamma-TuRC from Xenopus laevis at 4.8 angstrom global resolution, and identify a 14-spoked arrangement of GCP proteins and gamma-tubulins in a partially flexible open left-handed spiral with a uniform sequence of GCP variants. By forming specific interactions with other GCP proteins, the GCP6-specific insertion domain acts as a scaffold for the assembly of the gamma-TuRC. Unexpectedly, we identify actin as a bona fide structural component of the gamma-TuRC with functional relevance in microtubule nucleation. The spiral geometry of gamma-TuRC is suboptimal for microtubule nucleation and a controlled conformational rearrangement of the gamma-TuRC is required for its activation. Collectively, our cryo-electron microscopy reconstructions provide detailed insights into the molecular organization, assembly and activation mechanism of vertebrate gamma-TuRC, and will serve as a framework for the mechanistic understanding of fundamental biological processes associated with microtubule nucleation, such as meiotic and mitotic spindle formation and centriole biogenesis(4).


The cryo-EM structure of the gamma-tubulin ring complex (gamma-TuRC) from Xenopus laevis provides insights into the molecular organization of the complex, and shows that actin is a structural component that is functionally relevant to microtubule nucleation.


  
Cortical pattern generation during dexterous movement is input-driven 期刊论文
NATURE, 2020, 577 (7790) : 386-+
作者:  Cyranoski, David
收藏  |  浏览/下载：22/0  |  提交时间：2020/07/03

The motor cortex controls skilled arm movement by sending temporal patterns of activity to lower motor centres(1). Local cortical dynamics are thought to shape these patterns throughout movement execution(2-4). External inputs have been implicated in setting the initial state of the motor cortex(5,6), but they may also have a pattern-generating role. Here we dissect the contribution of local dynamics and inputs to cortical pattern generation during a prehension task in mice. Perturbing cortex to an aberrant state prevented movement initiation, but after the perturbation was released, cortex either bypassed the normal initial state and immediately generated the pattern that controls reaching or failed to generate this pattern. The difference in these two outcomes was probably a result of external inputs. We directly investigated the role of inputs by inactivating the thalamus  this perturbed cortical activity and disrupted limb kinematics at any stage of the movement. Activation of thalamocortical axon terminals at different frequencies disrupted cortical activity and arm movement in a graded manner. Simultaneous recordings revealed that both thalamic activity and the current state of cortex predicted changes in cortical activity. Thus, the pattern generator for dexterous arm movement is distributed across multiple, strongly interacting brain regions.


  
Mutations that prevent caspase cleavage of RIPK1 cause autoinflammatory disease 期刊论文
NATURE, 2020, 577 (7788) : 103-+
作者:  Lalaoui, Najoua;  Boyden, Steven E.;  Oda, Hirotsugu;  Wood, Geryl M.;  Stone, Deborah L.;  Chau, Diep;  Liu, Lin;  Stoffels, Monique;  Kratina, Tobias;  Lawlor, Kate E.;  Zaal, Kristien J. M.;  Hoffmann, Patrycja M.;  Etemadi, Nima;  Shield-Artin, Kristy;  Biben, Christine;  Tsai, Wanxia Li;  Blake, Mary D.;  Kuehn, Hye Sun;  Yang, Dan;  Anderton, Holly;  Silke, Natasha;  Wachsmuth, Laurens;  Zheng, Lixin;  Moura, Natalia Sampaio;  Beck, David B.;  Gutierrez-Cruz, Gustavo;  Ombrello, Amanda K.;  Pinto-Patarroyo, Gineth P.;  Kueh, Andrew J.;  Herold, Marco J.;  Hall, Cathrine;  Wang, Hongying;  Chae, Jae Jin;  Dmitrieva, Natalia I.;  McKenzie, Mark;  Light, Amanda;  Barham, Beverly K.;  Jones, Anne;  Romeo, Tina M.;  Zhou, Qing;  Aksentijevich, Ivona;  Mullikin, James C.;  Gross, Andrew J.;  Shum, Anthony K.;  Hawkins, Edwin D.;  Masters, Seth L.;  Lenardo, Michael J.;  Boehm, Manfred;  Rosenzweig, Sergio D.;  Pasparakis, Manolis;  Voss, Anne K.;  Gadina, Massimo;  Kastner, Daniel L.;  Silke, John
收藏  |  浏览/下载：70/0  |  提交时间：2020/07/03

RIPK1 is a key regulator of innate immune signalling pathways. To ensure an optimal inflammatory response, RIPK1 is regulated post-translationally by well-characterized ubiquitylation and phosphorylation events, as well as by caspase-8-mediated cleavage1-7. The physiological relevance of this cleavage event remains unclear, although it is thought to inhibit activation of RIPK3 and necroptosis8. Here we show that the heterozygous missense mutations D324N, D324H and D324Y prevent caspase cleavage of RIPK1 in humans and result in an early-onset periodic fever syndrome and severe intermittent lymphadenopathy-a condition we term '  cleavage-resistant RIPK1-induced autoinflammatory syndrome'  . To define the mechanism for this disease, we generated a cleavage-resistant Ripk1(D325A) mutant mouse strain. Whereas Ripk1(-/-) mice died postnatally from systemic inflammation, Ripk1(D325A/D325A) mice died during embryogenesis. Embryonic lethality was completely prevented by the combined loss of Casp8 and Ripk3, but not by loss of Ripk3 or Mlkl alone. Loss of RIPK1 kinase activity also prevented Ripk1(D325A/D325A) embryonic lethality, although the mice died before weaning from multi-organ inflammation in a RIPK3-dependent manner. Consistently, Ripk1(D325A/D325A) and Ripk1(D325A/+) cells were hypersensitive to RIPK3-dependent TNF-induced apoptosis and necroptosis. Heterozygous Ripk1(D325A/+) mice were viable and grossly normal, but were hyper-responsive to inflammatory stimuli in vivo. Our results demonstrate the importance of caspase-mediated RIPK1 cleavage during embryonic development and show that caspase cleavage of RIPK1 not only inhibits necroptosis but also maintains inflammatory homeostasis throughout life.


  
A dominant autoinflammatory disease caused by non-cleavable variants of RIPK1 期刊论文
NATURE, 2020, 577 (7788) : 109-+
作者:  Tao, Panfeng;  Sun, Jinqiao;  Wu, Zheming;  Wang, Shihao;  Wang, Jun;  Li, Wanjin;  Pan, Heling;  Bai, Renkui;  Zhang, Jiahui;  Wang, Ying;  Lee, Pui Y.;  Ying, Wenjing;  Zhou, Qinhua;  Hou, Jia;  Wang, Wenjie;  Sun, Bijun;  Yang, Mi;  Liu, Danru;  Fang, Ran;  Han, Huan;  Yang, Zhaohui;  Huang, Xin;  Li, Haibo;  Deuitch, Natalie;  Zhang, Yuan;  Dissanayake, Dilan;  Haude, Katrina;  McWalter, Kirsty;  Roadhouse, Chelsea;  MacKenzie, Jennifer J.;  Laxer, Ronald M.;  Aksentijevich, Ivona;  Yu, Xiaomin;  Wang, Xiaochuan;  Yuan, Junying;  Zhou, Qing
收藏  |  浏览/下载：57/0  |  提交时间：2020/07/03

Activation of RIPK1 controls TNF-mediated apoptosis, necroptosis and inflammatory pathways(1). Cleavage of human and mouse RIPK1 after residues D324 and D325, respectively, by caspase-8 separates the RIPK1 kinase domain from the intermediate and death domains. The D325A mutation in mouse RIPK1 leads to embryonic lethality during mouse development(2,3). However, the functional importance of blocking caspase-8-mediated cleavage of RIPK1 on RIPK1 activation in humans is unknown. Here we identify two families with variants in RIPK1 (D324V and D324H) that lead to distinct symptoms of recurrent fevers and lymphadenopathy in an autosomaldominant manner. Impaired cleavage of RIPK1 D324 variants by caspase-8 sensitized patients'  peripheral blood mononuclear cells to RIPK1 activation, apoptosis and necroptosis induced by TNF. The patients showed strong RIPK1-dependent activation of inflammatory signalling pathways and overproduction of inflammatory cytokines and chemokines compared with unaffected controls. Furthermore, we show that expression of the RIPK1 mutants D325V or D325H in mouse embryonic fibroblasts confers not only increased sensitivity to RIPK1 activation-mediated apoptosis and necroptosis, but also induction of pro-inflammatory cytokines such as IL-6 and TNF. By contrast, patient-derived fibroblasts showed reduced expression of RIPK1 and downregulated production of reactive oxygen species, resulting in resistance to necroptosis and ferroptosis. Together, these data suggest that human non-cleavable RIPK1 variants promote activation of RIPK1, and lead to an autoinflammatory disease characterized by hypersensitivity to apoptosis and necroptosis and increased inflammatory response in peripheral blood mononuclear cells, as well as a compensatory mechanism to protect against several pro-death stimuli in fibroblasts.


  
Impaired cell fate through gain-of-function mutations in a chromatin reader 期刊论文
NATURE, 2020, 577 (7788) : 121-+
作者:  Wan, Liling;  Chong, Shasha;  Xuan, Fan;  Liang, Angela;  Cui, Xiaodong;  Gates, Leah;  Carroll, Thomas S.;  Li, Yuanyuan;  Feng, Lijuan;  Chen, Guochao;  Wang, Shu-Ping;  Ortiz, Michael V.;  Daley, Sara K.;  Wang, Xiaolu;  Xuan, Hongwen;  Kentsis, Alex;  Muir, Tom W.;  Roeder, Robert G.;  Li, Haitao;  Li, Wei;  Tjian, Robert;  Wen, Hong;  Allis, C. David
收藏  |  浏览/下载：25/0  |  提交时间：2020/07/03

Modifications of histone proteins have essential roles in normal development and human disease. Recognition of modified histones by '  reader'  proteins is a key mechanism that mediates the function of histone modifications, but how the dysregulation of these readers might contribute to disease remains poorly understood. We previously identified the ENL protein as a reader of histone acetylation via its YEATS domain, linking it to the expression of cancer-driving genes in acute leukaemia1. Recurrent hotspot mutations have been found in the ENL YEATS domain in Wilms tumour2,3, the most common type of paediatric kidney cancer. Here we show, using human and mouse cells, that these mutations impair cell-fate regulation by conferring gain-of-function in chromatin recruitment and transcriptional control. ENL mutants induce gene-expression changes that favour a premalignant cell fate, and, in an assay for nephrogenesis using murine cells, result in undifferentiated structures resembling those observed in human Wilms tumour. Mechanistically, although bound to largely similar genomic loci as the wild-type protein, ENL mutants exhibit increased occupancy at a subset of targets, leading to a marked increase in the recruitment and activity of transcription elongation machinery that enforces active transcription from target loci. Furthermore, ectopically expressed ENL mutants exhibit greater self-association and form discrete and dynamic nuclear puncta that are characteristic of biomolecular hubs consisting of local high concentrations of regulatory factors. Such mutation-driven ENL self-association is functionally linked to enhanced chromatin occupancy and gene activation. Collectively, our findings show that hotspot mutations in a chromatinreader domain drive self-reinforced recruitment, derailing normal cell-fate control during development and leading to an oncogenic outcome.


  
IL-17a promotes sociability in mouse models of neurodevelopmental disorders 期刊论文
NATURE, 2020, 577 (7789) : 249-+
作者:  Reed, Michael Douglas;  Yim, Yeong Shin;  Wimmer, Ralf D.;  Kim, Hyunju;  Ryu, Changhyeon;  Welch, Gwyneth Margaret;  Andina, Matias;  King, Hunter Oren;  Waisman, Ari;  Halassa, Michael M.;  Huh, Jun R.;  Choi, Gloria B.
收藏  |  浏览/下载：28/0  |  提交时间：2020/07/03

A subset of children with autism spectrum disorder appear to show an improvement in their behavioural symptoms during the course of a fever, a sign of systemic inflammation(1,2). Here we elucidate the molecular and neural mechanisms that underlie the beneficial effects of inflammation on social behaviour deficits in mice. We compared an environmental model of neurodevelopmental disorders in which mice were exposed to maternal immune activation (MIA) during embryogenesis(3,4) with mouse models that are genetically deficient for contactin-associated protein-like 2 (Cntnap2)(5), fragile X mental retardation-1 (Fmr1)(6) or Sh3 and multiple ankyrin repeat domains 3 (Shank3)(7). We establish that the social behaviour deficits in offspring exposed to MIA can be temporarily rescued by the inflammatory response elicited by the administration of lipopolysaccharide (LPS). This behavioural rescue was accompanied by a reduction in neuronal activity in the primary somatosensory cortex dysgranular zone (S1DZ), the hyperactivity of which was previously implicated in the manifestation of behavioural phenotypes associated with offspring exposed to MIA(8). By contrast, we did not observe an LPS-induced rescue of social deficits in the monogenic models. We demonstrate that the differences in responsiveness to the LPS treatment between the MIA and the monogenic models emerge from differences in the levels of cytokine production. LPS treatment in monogenic mutant mice did not induce amounts of interleukin-17a (IL-17a) comparable to those induced in MIA offspring  bypassing this difference by directly delivering IL-17a into S1DZ was sufficient to promote sociability in monogenic mutant mice as well as in MIA offspring. Conversely, abrogating the expression of IL-17 receptor subunit a (IL-17Ra) in the neurons of the S1DZ eliminated the ability of LPS to reverse the sociability phenotypes in MIA offspring. Our data support a neuroimmune mechanism that underlies neurodevelopmental disorders in which the production of IL-17a during inflammation can ameliorate the expression of social behaviour deficits by directly affecting neuronal activity in the central nervous system.


  
Fourth defence molecule completes antiviral line-up 期刊论文
NATURE, 2020, 581 (7808) : 266-267
作者:  Marshall, Michael
收藏  |  浏览/下载：8/0  |  提交时间：2020/07/03

Toll-like receptors can initiate an immune response when they detect signs of a viral or microbial threat. New insight into how such receptor activation drives defence programs should aid our efforts to understand autoimmune diseases.


Key adaptor protein found in a pathway that drives interferon production.


  
Structure and mechanism of the mitochondrial Ca2+ uniporter holocomplex 期刊论文
NATURE, 2020
作者:  Kalaany, Nada Y.;  Sabatini, David M.
收藏  |  浏览/下载：28/0  |  提交时间：2020/07/03

Mitochondria take up Ca2+ through the mitochondrial calcium uniporter complex to regulate energy production, cytosolic Ca2+ signalling and cell death(1,2). In mammals, the uniporter complex (uniplex) contains four core components: the pore-forming MCU protein, the gatekeepers MICU1 and MICU2, and an auxiliary subunit, EMRE, essential for Ca2+ transport(3-8). To prevent detrimental Ca2+ overload, the activity of MCU must be tightly regulated by MICUs, which sense changes in cytosolic Ca2+ concentrations to switch MCU on and off(9,10). Here we report cryo-electron microscopic structures of the human mitochondrial calcium uniporter holocomplex in inhibited and Ca2+-activated states. These structures define the architecture of this multicomponent Ca2+-uptake machinery and reveal the gating mechanism by which MICUs control uniporter activity. Our work provides a framework for understanding regulated Ca2+ uptake in mitochondria, and could suggest ways of modulating uniporter activity to treat diseases related to mitochondrial Ca2+ overload.


Cryo-electron microscopy reveals the structures of the mitochondrial calcium uniporter holocomplex in low- and high-calcium conditions, showing the gating mechanism that underlies uniporter activation in response to intracellular calcium signals.


  
Potential circadian effects on translational failure for neuroprotection 期刊论文
NATURE, 2020
作者:  Sakai, Akito;  Minami, Susumu;  Koretsune, Takashi;  Chen, Taishi;  Higo, Tomoya;  Wang, Yangming;  Nomoto, Takuya;  Hirayama, Motoaki;  Miwa, Shinji;  Nishio-Hamane, Daisuke;  Ishii, Fumiyuki;  Arita, Ryotaro;  Nakatsuji, Satoru
收藏  |  浏览/下载：28/0  |  提交时间：2020/07/03

Neuroprotectant strategies that have worked in rodent models of stroke have failed to provide protection in clinical trials. Here we show that the opposite circadian cycles in nocturnal rodents versus diurnal humans(1,2) may contribute to this failure in translation. We tested three independent neuroprotective approaches-normobaric hyperoxia, the free radical scavenger alpha-phenyl-butyl-tert-nitrone (alpha PBN), and the N-methyl-d-aspartic acid (NMDA) antagonist MK801-in mouse and rat models of focal cerebral ischaemia. All three treatments reduced infarction in day-time (inactive phase) rodent models of stroke, but not in night-time (active phase) rodent models of stroke, which match the phase (active, day-time) during which most strokes occur in clinical trials. Laser-speckle imaging showed that the penumbra of cerebral ischaemia was narrower in the active-phase mouse model than in the inactive-phase model. The smaller penumbra was associated with a lower density of terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)-positive dying cells and reduced infarct growth from 12 to 72 h. When we induced circadian-like cycles in primary mouse neurons, deprivation of oxygen and glucose triggered a smaller release of glutamate and reactive oxygen species, as well as lower activation of apoptotic and necroptotic mediators, in '  active-phase'  than in '  inactive-phase'  rodent neurons. alpha PBN and MK801 reduced neuronal death only in '  inactive-phase'  neurons. These findings suggest that the influence of circadian rhythm on neuroprotection must be considered for translational studies in stroke and central nervous system diseases.


Studies in rats and mice at different times of day suggest that the failure of neuroprotective strategies for stroke in translational studies might be related to the difference in circadian cycles between humans and rodents.