Recruitment into stress granules prevents irreversible aggregation of FUS protein mislocalized to the cytoplasm

Fused in sarcoma (FUS) belongs to the group of RNA-binding proteins implicated as underlying factors in amyotrophic lateral sclerosis (ALS) and certain other neurodegenerative diseases. Multiple FUS gene mutations have been linked to hereditary forms, and aggregation of FUS protein is believed to play an important role in pathogenesis of these diseases. In cultured cells, FUS variants with disease-associated amino acid substitutions or short deletions affecting nuclear localization signal (NLS) and causing cytoplasmic mislocalization can be sequestered into stress granules (SGs). We demonstrated that disruption of motifs responsible for RNA recognition and binding not only prevents SG recruitment, but also dramatically increases the protein propensity to aggregate in the cell cytoplasm with formation of juxtanuclear structures displaying typical features of aggresomes. Functional RNA-binding domains from TAR DNA-binding protein of 43 kDa (TDP-43) fused to highly aggregation-prone C-terminally truncated FUS protein restored the ability to enter SGs and prevented aggregation of the chimeric protein. Truncated FUS was also able to trap endogenous FUS molecules in the cytoplasmic aggregates. Our data indicate that RNA binding and recruitment to SGs protect cytoplasmic FUS from aggregation, and loss of this protection may trigger its pathological aggregation in vivo.     

Identification of PrP sequences essential for the interaction between the PrP polymers and Aβ peptide in a yeast-based assay

Alzheimer disease is associated with the accumulation of oligomeric amyloid β peptide (Aβ), accompanied by synaptic dysfunction and neuronal death. Polymeric form of prion protein (PrP), PrP^Sc, is implicated in transmissible spongiform encephalopathies (TSEs). Recently, it was shown that the monomeric cellular form of PrP (PrP^C), located on the neuron surface, binds Aβ oligomers (and possibly other β-rich conformers) via the PrP_23–27 and PrP_90–110 segments, acting as Aβ receptor. On the other hand, PrP^Sc polymers efficiently bind to Aβ monomers and accelerate their oligomerization. To identify specific PrP sequences that are essential for the interaction between PrP polymers and Aβ peptide, we have co-expressed Aβ and PrP (or its shortened derivatives), fused to different fluorophores, in the yeast cell. Our data show that the 90–110 and 28–89 regions of PrP control the binding of proteinase-resistant PrP polymers to the Aβ peptide, whereas the 23–27 segment of PrP is dispensable for this interaction. This indicates that the set of PrP fragments involved in the interaction with Aβ depends on PrP conformational state.     

Copy-number variation introduced by long transgenes compromises mouse male fertility independently of pachytene checkpoints

Chromosoma - Long transgenes are often used in mammalian genetics, e.g., to rescue mutations in large genes. In the course of experiments addressing the genetic basis of hybrid sterility caused by...     

Diversity of the major capsid genes (g23) of T4-like bacteriophages in the eutrophic Lake Kotokel in East Siberia, Russia

Numerous studies revealed high diversity of T4-like bacteriophages in various environments, but so far, little is known about T4-like virus diversity in freshwater bodies, particularly in eutrophic lakes. The present study was aimed at elucidating molecular diversity of T4-like bacteriophages in eutrophic Lake Kotokel located near Lake Baikal by partial sequencing of the major capsid genes (g23) of T4-like bacteriophages. The majority of g23 fragments from Lake Kotokel were most similar to those from freshwater lakes and paddy fields. Despite the proximity and direct water connection between Lake Kotokel and Lake Baikal, g23 sequence assemblages from two lakes were different. UniFrac analysis showed that uncultured T4-like viruses from Lake Kotokel tended to cluster with those from the distant lake of the same trophic status. This fact suggested that the trophic conditions affected the formation of viral populations, particularly of T4-like viruses, in freshwater environments.     

Lipid peroxidation depends on the clock 3111T/C gene polymorphism in menopausal women with Insomnia

ABSTRACT

A comparative analysis of lipid peroxidation processes and antioxidant defense system in Caucasian menopausal women with/without insomnia depending on the genotype of Clock 3111T/C gene polymorphism was performed. Two hundred and fourteen Caucasian menopausal women divided into control (without insomnia) and main group (with insomnia) were examined. Lipid peroxidation (conjugated dienes, thiobarbituric acid reactants) and antioxidant defense system parameters (?-tocopherol, retinol, reduced and oxidized glutathione, glutathione S-transferase, glutathione peroxidase, glutathione reductase, superoxide dismutase) were determined by spectrofluorophotometer and immunoenzymometric methods. Patients with insomnia carriers of the TT-genotype had a significantly higher thiobarbituric acid reactants level and glutathione peroxidase activity as compared to group with insomnia carriers of the minor 3111C-allele (p < .05). A comparative analysis of the parameters in the women of the main and control groups showed higher conjugated dienes, thiobarbituric acid reactants levels and lower retinol, reduced glutathione levels, glutathione reductase activity in women with insomnia carriers of the TT-genotype (p < .05). The carriers of the minor allele with insomnia had a higher conjugated dienes levels and lower glutathione peroxidase activity as compared to control (p < .05). Thus, lipid peroxidation and antioxidant system parameters in Caucasian menopausal women with insomnia depend on the Clock 3111T/C gene polymorphism.     

The antioxidant enzymes activity in leaves of inter-varietal substitution lines of wheat (Triticum aestivum L.) with different tolerance to soil water deficit

Understanding of the genetic basis of physiological properties, which are most relevant to water-deficit tolerance would be helpful for genomic-assisted improvement of bread wheat. A set of bread wheat inter-varietal single chromosome substitution lines (ISCSLs) of variety ‘Janetzkis Probat’ (JP) in the genetic background of ‘Saratovskaya’ 29 (S29) were used to reveal the critical chromosomes in wheat genome controlling tolerance to water deficit. The same lines were involved in the identification of chromosomes associated with the activity of antioxidant enzymes that are closely related to the detoxification of H₂O₂ [catalase (CAT), ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase (GR)]. The recipient cultivar S29 was highly drought tolerant while the donor JP was sensitive. Using non-metric multidimensional scaling of yield components and indices of drought tolerance/susceptibility chromosomes 2A and 4D, substitution in the genetic background of S29 was found to lead to a critical decrease of water-deficit tolerance. The drop of tolerance correlated with a sharp decline of cumulative activity of the catalase and the enzymes of ascorbate–glutathione cycle in wheat leaves. Clear evidence was obtained for the involvement of genes present on the homoeologous group 2 chromosomes in the control of GR and CAT activity. Substitution of the chromosome 4D had a significant reducing impact on the CAT activity level.     

Three-Dimensional Structure of CAP-Gly Domain of Mammalian Dynactin Determined by Magic Angle Spinning NMR Spectroscopy: Conformational Plasticity and Interactions with End-Binding Protein EB1

Microtubules and their associated proteins play important roles in vesicle and organelle transport, cell motility and cell division. Perturbation of these processes by mutation typically gives rise to severe pathological conditions. In our efforts to obtain atomic information on microtubule-associated protein/microtubule interactions with the goal to understand mechanisms that might potentially assist in the development of treatments for these diseases, we have determined the three-dimensional structure of CAP-Gly (cytoskeleton-associated protein, glycine-rich) domain of mammalian dynactin by magic angle spinning NMR spectroscopy. We observe two conformations in the β2 strand encompassing residues T43-V44-A45, residues that are adjacent to the disease-associated mutation, G59S. Upon binding of CAP-Gly to microtubule plus-end tracking protein EB1, the CAP-Gly shifts to a single conformer. We find extensive chemical shift perturbations in several stretches of residues of CAP-Gly upon binding to EB1, from which we define accurately the CAP-Gly/EB1 binding interface. We also observe that the loop regions may exhibit unique flexibility, especially in the GKNDG motif, which participates in the microtubule binding. This study in conjunction with our previous reports suggests that conformational plasticity is an intrinsic property of CAP-Gly likely due to its unusually high loop content and may be required for its biological functions.     

Fused in Sarcoma (FUS) Protein Lacking Nuclear Localization Signal (NLS) and Major RNA Binding Motifs Triggers Proteinopathy and Severe Motor Phenotype in Transgenic Mice

Dysfunction of two structurally and functionally related proteins, FUS and TAR DNA-binding protein of 43 kDa (TDP-43), implicated in crucial steps of cellular RNA metabolism can cause amyotrophic lateral sclerosis (ALS) and certain other neurodegenerative diseases. The proteins are intrinsically aggregate-prone and form non-amyloid inclusions in the affected nervous tissues, but the role of these proteinaceous aggregates in disease onset and progression is still uncertain. To address this question, we designed a variant of FUS, FUS 1–359, which is predominantly cytoplasmic, highly aggregate-prone, and lacks a region responsible for RNA recognition and binding. Expression of FUS 1–359 in neurons of transgenic mice, at a level lower than that of endogenous FUS, triggers FUSopathy associated with severe damage of motor neurons and their axons, neuroinflammatory reaction, and eventual loss of selective motor neuron populations. These pathological changes cause abrupt development of a severe motor phenotype at the age of 2.5–4.5 months and death of affected animals within several days of onset. The pattern of pathology in transgenic FUS 1–359 mice recapitulates several key features of human ALS with the dynamics of the disease progression compressed in line with shorter mouse lifespan. Our data indicate that neuronal FUS aggregation is sufficient to cause ALS-like phenotype in transgenic mice.     

Influence of temperature on the infradian growth rhythm in Ulva lactuca (Chlorophyta)

The vegetative growth of Ulva lactuca was studied to determine if the growth rate of the alga is driven by infradian rhythmicity. The influence of temperature on the infradian rhythm of growth was also investigated. Discs of Ulva were grown in controlled laboratory conditions at different combinations of temperature (5, 10, 15, 20°С) and irradiance (40 and 60 μmol photons m^?2 s^?1) under 12 : 12 h light : dark cycles. The growth rates exhibited a rhythmic pattern with one major peak every 2 or 3 days. Growth at 5 or 10°С increased the prevalence of 3-day cycles and maintained U. lactuca in the vegetative growth stage. In contrast, growth at 15 or 20°С provoked a predominance of the 2-day cycle and induced reproduction. The 2- or 3-day cycles were combined in longer cycles having a period close to 6 days. We suppose that the 2-, 3- and 6-day rhythms of physiological processes are related to large-scale Rossby and Kelvin waves, which produce oscillations in the geomagnetic field and seawater temperature with the same periods. The predominance of 2-day or 3-day fluctuations of the geomagnetic field and temperature probably determine the prevalence of reproduction and vegetative growth, respectively, in Ulva.