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Yuhan Zhao, Lihua Wu, Xuetian Yue, Cen Zhang, Jianming Wang, Jun Li, Xiaohui Sun, Yiming Zhu, Zhaohui Feng, Wenwei Hu
Tumor suppressor p53 prevents early death due to cancer development. However, the role of p53 in aging process and longevity has not been well-established. In humans, single nucleotide polymorphism (SNP) with either arginine (R72) or proline (P72) at codon 72 influences p53 activity; the P72 allele has a weaker p53 activity and function in tumor suppression. Here, employing a mouse model with knock-in of human TP53 gene carrying codon 72 SNP, we found that despite increased cancer risk, P72 mice that escape tumor development display a longer lifespan than R72 mice...
March 20, 2018: ELife
Pierre Yger, Giulia Lb Spampinato, Elric Esposito, Baptiste Lefebvre, Stéphane Deny, Christophe Gardella, Marcel Stimberg, Florian Jetter, Guenther Zeck, Serge Picaud, Jens Duebel, Olivier Marre
In recent years, multielectrode arrays and large silicon probes have been developed to record simultaneously between hundreds and thousands of electrodes packed with a high density. However, they require novel methods to extract the spiking activity of large ensembles of neurons. Here we developed a new toolbox to sort spikes from these large-scale extracellular data. To validate our method, we performed simultaneous extracellular and loose patch recordings in rodents to obtain 'ground truth' data, where the solution to this sorting problem is known for one cell...
March 20, 2018: ELife
George R Wendt, Julie Nr Collins, Jimin Pei, Mark S Pearson, Hayley M Bennett, Alex Loukas, Matthew Berriman, Nick V Grishin, James J Collins
Schistosomes infect more than 200 million people. These parasitic flatworms rely on a syncytial outer-coat called the tegument to survive within the vasculature of their host. Although the tegument is pivotal for their survival, little is known about maintenance of this tissue during the decades schistosomes survive in the bloodstream. Here, we demonstrate that the tegument relies on stem cells (neoblasts) to specify fusogenic progenitors that replace tegumental cells lost to turnover. Molecular characterization of neoblasts and tegumental progenitors led to the discovery of two flatworm-specific zinc finger proteins that are essential for tegumental cell specification...
March 20, 2018: ELife
Laurelle Jackson, Jessica Hunter, Sandile Cele, Isabella Markham Ferreira, Andrew C Young, Farina Karim, Rajhmun Madansein, Kaylesh J Dullabh, Chih-Yuan Chen, Noel J Buckels, Yashica Ganga, Khadija Khan, Mikael Boulle, Gila Lustig, Richard A Neher, Alex Sigal
HIV has been reported to be cytotoxic in vitro and in lymph node infection models. Using a computational approach, we found that partial inhibition of transmissions of multiple virions per cell could lead to increased numbers of live infected cells. If the number of viral DNA copies remains above one after inhibition, then eliminating the surplus viral copies reduces cell death. Using a cell line, we observed increased numbers of live infected cells when infection was partially inhibited with the antiretroviral efavirenz or neutralizing antibody...
March 20, 2018: ELife
Michelle E Maxson, Xenia Naj, Teresa R O'Meara, Jonathan D Plumb, Leah E Cowen, Sergio Grinstein
Candida albicans hyphae can reach enormous lengths, precluding their internalization by phagocytes. Nevertheless, macrophages engulf a portion of the hypha, generating incompletely sealed tubular phagosomes. These frustrated phagosomes are stabilized by a thick cuff of F-actin that polymerizes in response to non-canonical activation of integrins by fungal glycan. Despite their continuity, the surface and invaginating phagosomal membranes retain a strikingly distinct lipid composition. PtdIns(4,5)P2 is present at the plasmalemma but is not detectable in the phagosomal membrane, while PtdIns(3)P and PtdIns(3,4,5)P3 co-exist in the phagosomes yet are absent from the surface membrane...
March 19, 2018: ELife
Florentina Soto, Lei Zhao, Daniel Kerschensteiner
Synaptic cell adhesion molecules (CAMs) promote synapse formation in the developing nervous system. To what extent they maintain and can restore connections in the mature nervous system is unknown. Furthermore, how synaptic CAMs affect the growth of synapse-bearing neurites is unclear. Here, we use adeno-associated viruses (AAVs) to delete, re-, and overexpress the synaptic CAM NGL2 in individual retinal horizontal cells. When we removed NGL2 from horizontal cells, their axons overgrew and formed fewer synapses, irrespective of whether Ngl2 was deleted during development or in mature circuits...
March 19, 2018: ELife
Carla Lloret-Fernández, Miren Maicas, Carlos Mora-Martínez, Alejandro Artacho, Angela Jimeno-Martín, Laura Chirivella, Peter Weinberg, Nuria Flames
Cell differentiation is controlled by individual transcription factors (TFs) that together activate a selection of enhancers in specific cell types. How these combinations of TFs identify and activate their target sequences remains poorly understood. Here, we identify the cis -regulatory transcriptional code that controls the differentiation of serotonergic HSN neurons in C. elegans . Activation of the HSN transcriptome is directly orchestrated by a collective of six TFs. Binding site clusters for this TF collective form a regulatory signature that is sufficient for de novo identification of HSN neuron functional enhancers...
March 19, 2018: ELife
Zhipeng Zhou, Yunkun Dang, Mian Zhou, Haiyan Yuan, Yi Liu
Codon usage biases are found in all genomes and influence protein expression levels. The codon usage effect on protein expression was thought to be mainly due to its impact on translation. Here we show that transcription termination is an important driving force for codon usage bias in eukaryotes. Using Neurospora crassa as a model organism, we demonstrated that introduction of rare codons results in premature transcription termination (PTT) within open reading frames and the abolishment of full-length mRNA...
March 16, 2018: ELife
Eric M Hill, Christian P Petersen
Most animals undergo homeostatic tissue maintenance, yet those capable of robust regeneration in adulthood use mechanisms significantly overlapping with homeostasis. Here we show in planarians that modulations to body-wide patterning systems shift the target site for eye regeneration while still enabling homeostasis of eyes outside this region. The uncoupling of homeostasis and regeneration, which can occur during normal positional rescaling after axis truncation, is not due to altered injury signaling or stem cell activity, nor specific to eye tissue...
March 16, 2018: ELife
Ziling Fang, Bo Cao, Jun-Ming Liao, Jun Deng, Kevin D Plummer, Peng Liao, Tao Liu, Wensheng Zhang, Kun Zhang, Li Li, David Margolin, Shelya X Zeng, Jianping Xiong, Hua Lu
Ribosomal proteins (RPs) play important roles in modulating the MDM2-p53 pathway. However, less is known about the upstream regulators of the RPs. Here we identify SPIN1 (Spindlin 1) as a novel binding partner of human RPL5/uL18 that is important for this pathway. SPIN1 ablation activates p53, suppresses cell growth, reduces clonogenic ability, and induces apoptosis of human cancer cells. Mechanistically, SPIN1 sequesters uL18 in the nucleolus, preventing it from interacting with MDM2, and thereby alleviating uL18-mediated inhibition of MDM2 ubiquitin ligase activity towards p53...
March 16, 2018: ELife
Chang-Hui Tsao, Chien-Chun Chen, Chen-Han Lin, Hao-Yu Yang, Suewei Lin
The fruit fly can evaluate its energy state and decide whether to pursue food-related cues. Here, we reveal that the mushroom body (MB) integrates hunger and satiety signals to control food-seeking behavior. We have discovered five pathways in the MB essential for hungry flies to locate and approach food. Blocking the MB-intrinsic Kenyon cells (KCs) and the MB output neurons (MBONs) in these pathways impairs food-seeking behavior. Starvation bi-directionally modulates MBON responses to a food odor, suggesting that hunger and satiety controls occur at the KC-to-MBON synapses...
March 16, 2018: ELife
Maud Martin, Alexandra Veloso, Jingchao Wu, Eugene A Katrukha, Anna Akhmanova
Microtubules control different aspects of cell polarization. In cells with a radial microtubule system, a pivotal role in setting up asymmetry is attributed to the relative positioning of the centrosome and the nucleus. Here, we show that centrosome loss had no effect on the ability of endothelial cells to polarize and move in 2D and 3D environments. In contrast, non-centrosomal microtubules stabilized by the microtubule minus-end-binding protein CAMSAP2 were required for directional migration on 2D substrates and for the establishment of polarized cell morphology in soft 3D matrices...
March 16, 2018: ELife
Neel H Shah, Mark Löbel, Arthur Weiss, John Kuriyan
The specificity of tyrosine kinases is predominantly attributed to localization effects dictated by non-catalytic domains. We developed a method to profile the specificities of tyrosine kinases by combining bacterial surface-display of peptide libraries with next-generation sequencing. Using this, we showed that the tyrosine kinase ZAP-70, which is critical for T cell signaling, discriminates substrates through an electrostatic selection mechanism encoded within its catalytic domain (Shah et al. 2016). Here, we expand this high-throughput platform to analyze the intrinsic specificity of any tyrosine kinase domain against thousands of peptides derived from human tyrosine phosphorylation sites...
March 16, 2018: ELife
Laura Jeacock, Joana Faria, David Horn
Protein abundance differs from a few to millions of copies per cell. Trypanosoma brucei presents an excellent model for studies on codon bias and differential gene expression because transcription is broadly unregulated and uniform across the genome. T. brucei is also a major human and animal protozoal pathogen. Here, an experimental assessment, using synthetic reporter genes, revealed that GC3 codons have a major positive impact on both mRNA and protein abundance. Our estimates of relative expression, based on coding sequences alone (codon usage and sequence length), are within 2-fold of the observed values for the majority of measured cellular mRNAs (n>7000) and proteins (n>2000)...
March 15, 2018: ELife
Marco M Manni, Marion L Tiberti, Sophie Pagnotta, Hélène Barelli, Romain Gautier, Bruno Antonny
Phospholipid membranes form cellular barriers but need to be flexible enough to divide by fission. Phospholipids generally contain a saturated fatty acid (FA) at position sn1 whereas the sn2 -FA is saturated, monounsaturated or polyunsaturated. Our understanding of the impact of phospholipid unsaturation on membrane flexibility and fission is fragmentary. Here, we provide a comprehensive view of the effects of the FA profile of phospholipids on membrane vesiculation by dynamin and endophilin. Coupled to simulations, this analysis indicates that: (i) phospholipids with two polyunsaturated FAs make membranes prone to vesiculation but highly permeable; (ii) asymmetric sn1 -saturated- sn2 -polyunsaturated phospholipids provide a tradeoff between efficient membrane vesiculation and low membrane permeability; (iii) When incorporated into phospholipids, docosahexaenoic acid (DHA; omega-3) makes membranes more deformable than arachidonic acid (omega-6)...
March 15, 2018: ELife
Janaina de Freitas Nascimento, Steven Kelly, Jack Sunter, Mark Carrington
Selective transcription of individual protein coding genes does not occur in trypanosomes and the cellular copy number of each mRNA must be determined post-transcriptionally. Here, we provide evidence that codon choice directs the levels of constitutively expressed mRNAs. First, a novel codon usage metric, the gene expression codon adaptation index (geCAI), was developed that maximised the relationship between codon choice and the measured abundance for a transcriptome. Second, geCAI predictions of mRNA levels were tested using differently coded GFP transgenes and were successful over a 25-fold range, similar to the variation in endogenous mRNAs...
March 15, 2018: ELife
Sona Gregorova, Vaclav Gergelits, Irena Chvatalova, Tanmoy Bhattacharyya, Barbora Valiskova, Vladana Fotopulosova, Petr Jansa, Diana Wiatrowska, Jiri Forejt
Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9 , the only known vertebrate hybrid sterility gene, causes failure of meiotic chromosome synapsis and infertility in male hybrids between two mouse subspecies. But within species Prdm9 determines the sites of programmed DNA double-strand breaks and meiotic recombination hotspots. To investigate the relation between Prdm9 -controlled meiotic arrest and asynapsis, we inserted random stretches of consubspecific homology on several autosomal pairs in sterile hybrids and analyzed their ability to form synaptonemal complexes and rescue male fertility...
March 14, 2018: ELife
Guanglin Xing, Moyi Li, Yichen Sun, Menglong Rui, Yan Zhuang, Huihui Lv, Junhai Han, Zhengping Jia, Wei Xie
Neuroligins are postsynaptic adhesion molecules that are essential for postsynaptic specialization and synaptic function. But the underlying molecular mechanisms of Neuroligin functions remain unclear. We found that Drosophila Neuroligin1 (DNlg1) regulates synaptic structure and function through WAVE regulatory complex (WRC)-mediated postsynaptic actin reorganization. The disruption of DNlg1, DNlg2, or their presynaptic partner Neurexin (DNrx) led to a dramatic decrease in the amount of F-actin. Further study showed that DNlg1, but not DNlg2 or DNlg3, directly interacts with the WRC via its C-terminal interacting receptor sequence...
March 14, 2018: ELife
Matthew Tien, Aretha Fiebig, Sean Crosson
Cells adapt to shifts in their environment by remodeling transcription. Measuring changes in transcription at the genome scale is now routine, but defining the functional significance of individual genes within large gene expression datasets remains a major challenge. We applied a network-based algorithm to interrogate publicly available gene expression data to predict genes that serve major functional roles in Caulobacter crescentus stress survival. This approach identified GsrN, a conserved small RNA that is directly activated by the general stress sigma factor, σT , and functions as a potent post-transcriptional regulator of survival across distinct conditions including osmotic and oxidative stress...
March 14, 2018: ELife
Antoine Guérin, Gaspard Kerner, Nico Marr, Janet G Markle, Florence Fenollar, Natalie Wong, Sabri Boughorbel, Danielle T Avery, Cindy S Ma, Salim Bougarn, Matthieu Bouaziz, Vivien Beziat, Erika Della Mina, Carmen Oleaga-Quintas, Tomi Lazarovt, Lisa Worley, Tina Nguyen, Etienne Patin, Caroline Deswarte, Rubén Martinez-Barricarte, Soraya Boucherit, Xavier Ayral, Sophie Edouard, Stéphanie Boisson-Dupuis, Vimel Rattina, Benedetta Bigio, Guillaume Vogt, Frédéric Geissmann, Lluis Quintana-Murci, Damien Chaussabel, Stuart G Tangye, Didier Raoult, Laurent Abel, Jacinta Bustamante, Jean-Laurent Casanova
Most humans are exposed to Tropheryma whipplei (Tw). Whipple's disease (WD) strikes only a small minority of individuals infected with Tw (<0.01%), whereas asymptomatic chronic carriage is more common (<25%). We studied a multiplex kindred, containing four WD patients and five healthy Tw chronic carriers. We hypothesized that WD displays autosomal dominant (AD) inheritance, with age-dependent incomplete penetrance. We identified a single very rare non-synonymous mutation in the four patients: the private R98W variant of IRF4, a transcription factor involved in immunity...
March 14, 2018: ELife
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