Spatiotemporal variation of mammalian protein complex stoichiometries

Table reporting the summary of quantified complex members and their regulation. (XLSX 179 kb

Pre-assembled Nuclear Pores Insert into the Nuclear Envelope during Early Development

SummaryNuclear pore complexes (NPCs) span the nuclear envelope (NE) and mediate nucleocytoplasmic transport. In metazoan oocytes and early embryos, NPCs reside not only within the NE, but also at some endoplasmic reticulum (ER) membrane sheets, termed annulate lamellae (AL). Although a role for AL as NPC storage pools has been discussed, it remains controversial whether and how they contribute to the NPC density at the NE. Here, we show that AL insert into the NE as the ER feeds rapid nuclear expansion in Drosophila blastoderm embryos. We demonstrate that NPCs within AL resemble pore scaffolds that mature only upon insertion into the NE. We delineate a topological model in which NE openings are critical for AL uptake that nevertheless occurs without compromising the permeability barrier of the NE. We finally show that this unanticipated mode of pore insertion is developmentally regulated and operates prior to gastrulation

Integrated Structural Analysis of the Human Nuclear Pore Complex Scaffold

SummaryThe nuclear pore complex (NPC) is a fundamental component of all eukaryotic cells that facilitates nucleocytoplasmic exchange of macromolecules. It is assembled from multiple copies of about 30 nucleoporins. Due to its size and complex composition, determining the structure of the NPC is an enormous challenge, and the overall architecture of the NPC scaffold remains elusive. In this study, we have used an integrated approach based on electron tomography, single-particle electron microscopy, and crosslinking mass spectrometry to determine the structure of a major scaffold motif of the human NPC, the Nup107 subcomplex, in both isolation and integrated into the NPC. We show that 32 copies of the Nup107 subcomplex assemble into two reticulated rings, one each at the cytoplasmic and nuclear face of the NPC. This arrangement may explain how changes of the diameter are realized that would accommodate transport of huge cargoes

Structural Basis of BRCC36 Function in DNA Repair and Immune Regulation

In mammals, ∼100 deubiquitinases act on ∼20,000 intracellular ubiquitination sites. Deubiquitinases are commonly regarded as constitutively active, with limited regulatory and targeting capacity. The BRCA1-A and BRISC complexes serve in DNA double-strand break repair and immune signaling and contain the lysine-63 linkage-specific BRCC36 subunit that is functionalized by scaffold subunits ABRAXAS and ABRO1, respectively. The molecular basis underlying BRCA1-A and BRISC function is currently unknown. Here we show that in the BRCA1-A complex structure, ABRAXAS integrates the DNA repair protein RAP80 and provides a high-affinity binding site that sequesters the tumor suppressor BRCA1 away from the break site. In the BRISC structure, ABRO1 binds SHMT2α, a metabolic enzyme enabling cancer growth in hypoxic environments, which we find prevents BRCC36 from binding and cleaving ubiquitin chains. Our work explains modularity in the BRCC36 DUB family, with different adaptor subunits conferring diversified targeting and regulatory functions.ISSN:1097-2765ISSN:1097-416

High frequency of low-count monoclonal B-cell lymphocytosis in hospitalized COVID-19 patients

Low-count monoclonal B-cell lymphocytosis (MBLlo, <500 clonal B-cells/μL) is a highly prevalent condition in the general population (4% to 16% of otherwise healthy adults), which increases significantly with age.1-7 In most cases, clonal B-cells share phenotypic and cytogenetic features with chronic lymphocytic leukemia (CLL), but only a small fraction (≈1.8%) progresses to high-count MBL (MBLhi; ≥500 and <5000 clonal B-cells/μL)3 in the medium-term.8 However, previous reports showed that MBLlo subjects had an increased risk of severe infections in association with a (predominantly) secondary antibody deficiency,8-10 suggesting that MBLlo might be a risk marker for developing more severe infections.This work was supported by the Instituto de Salud Carlos III (Ministerio de Ciencia e Innovación, Madrid, Spain, and FONDOS FEDER (a way to build Europe) grants CB16/12/00400 (CIBERONC), COV20/00386, and PI17/00399; the Consejería de Educación and the Gerencia Regional de Salud, Consejería de Sanidad from Junta de Castilla y León (Valladolid, Spain) grants SA109P20 and GRS-COVID-33/A/20; the European Regional Development Fund (INTERREG POCTEP Spain-Portugal) grant 0639-IDIAL-NET-3-3; and the CRUK (United Kingdom), Fundación AECC (Spain), and Associazione Italiana per la Ricerca Sul Cancro (Italy) “Early Cancer Research Initiative Network on MBL (ECRINM3)” ACCELERATOR award. G.O.-A. is supported by a grant from the Consejería de Educación, Junta de Castilla y León (Valladolid, Spain); B.F.-H. was supported by grant 0639-IDIAL-NET-3-3.Peer reviewe

Mutations, Genes, and Phenotypes Related to Movement Disorders and Ataxias

26 páginas, 4 figuras, 3 tablasOur clinical series comprises 124 patients with movement disorders (MDs) and/or ataxia with cerebellar atrophy (CA), many of them showing signs of neurodegeneration with brain iron accumulation (NBIA). Ten NBIA genes are accepted, although isolated cases compatible with abnormal brain iron deposits are known. The patients were evaluated using standardised clinical assessments of ataxia and MDs. First, NBIA genes were analysed by Sanger sequencing and 59 patients achieved a diagnosis, including the detection of the founder mutation PANK2 p.T528M in Romani people. Then, we used a custom panel MovDisord and/or exome sequencing; 29 cases were solved with a great genetic heterogeneity (34 different mutations in 23 genes). Three patients presented brain iron deposits with Fe-sensitive MRI sequences and mutations in FBXO7, GLB1, and KIF1A, suggesting an NBIA-like phenotype. Eleven patients showed very early-onset ataxia and CA with cortical hyperintensities caused by mutations in ITPR1, KIF1A, SPTBN2, PLA2G6, PMPCA, and PRDX3. The novel variants were investigated by structural modelling, luciferase analysis, transcript/minigenes studies, or immunofluorescence assays. Our findings expand the phenotypes and the genetics of MDs and ataxias with early-onset CA and cortical hyperintensities and highlight that the abnormal brain iron accumulation or early cerebellar gliosis may resembling an NBIA phenotype.This work was supported by the Instituto de Salud Carlos III (ISCIII)—Subdirección General de Evaluación y Fomento de la Investigación within the framework of the National R + D+I Plan co-funded with European Regional Development Funds (ERDF) [Grants PI18/00147 and PI21/00103 to CE]; the Fundació La Marató TV3 [Grants 20143130 and 20143131 to BPD and CE]; and by the Generalitat Valenciana [Grant PROMETEO/2018/135 to CE]. Part of the equipment employed in this work was funded by Generalitat Valenciana and co-financed with ERDF (OP ERDF of Comunitat Valenciana 2014–2020). PS had an FPU-PhD fellowship funded by the Spanish Ministry of Education, Culture and Sport [FPU15/00964]. IH has a PFIS-PhD fellowship [FI19/00072]. ASM has a contract funded by the Spanish Foundation Per Amor a l’Art (FPAA)Peer reviewe

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Conserved exchange of paralog proteins during neuronal differentiation

Gene duplication enables the emergence of new functions by lowering the evolutionary pressure that is posed on the ancestral genes. Previous studies have highlighted the role of specific paralog genes during cell differentiation, for example, in chromatin remodeling complexes. It remains unexplored whether similar mechanisms extend to other biological functions and whether the regulation of paralog genes is conserved across species. Here, we analyze the expression of paralogs across human tissues, during development and neuronal differentiation in fish, rodents and humans. Whereas ∼80% of paralog genes are co-regulated, a subset of paralogs shows divergent expression profiles, contributing to variability of protein complexes. We identify 78 substitutions of paralog pairs that occur during neuronal differentiation and are conserved across species. Among these, we highlight a substitution between the paralogs SEC23A and SEC23B members of the COPII complex. Altering the ratio between these two genes via RNAi-mediated knockdown is sufficient to influence neuron differentiation. We propose that remodeling of the vesicular transport system via paralog substitutions is an evolutionary conserved mechanism enabling neuronal differentiation.ISSN:2575-107