Structural properties and neuronal toxicity of amyotrophic lateral sclerosis–associated Cu/Zn superoxide dismutase 1 aggregates

The appearance of protein aggregates is a characteristic of protein misfolding disorders including familial amyotrophic lateral sclerosis, a neurodegenerative disease caused by inherited mutations in Cu/Zn superoxide dismutase 1 (SOD1). Here, we use live cell imaging of neuronal and nonneuronal cells to show that SOD1 mutants (G85R and G93A) form an aggregate structure consisting of immobile scaffolds, through which noninteracting cellular proteins can diffuse. Hsp70 transiently interacts, in a chaperone activity-dependent manner, with these mutant SOD1 aggregate structures. In contrast, the proteasome is sequestered within the aggregate structure, an event associated with decreased degradation of a proteasomal substrate. Through the use of time-lapse microscopy of individual cells, we show that nearly all (90%) aggregate-containing cells express higher levels of mutant SOD1 and died within 48 h, whereas 70% of cells expressing a soluble mutant SOD1 survived. Our results demonstrate that SOD1 G85R and G93A mutants form a distinct class of aggregate structures in cells destined for neuronal cell death

Macro-level Modeling of the Response of <i>C. elegans</i> Reproduction to Chronic Heat Stress

A major goal of systems biology is to understand how organism-level behavior arises from a myriad of molecular interactions. Often this involves complex sets of rules describing interactions among a large number of components. As an alternative, we have developed a simple, macro-level model to describe how chronic temperature stress affects reproduction in C. elegans. Our approach uses fundamental engineering principles, together with a limited set of experimentally derived facts, and provides quantitatively accurate predictions of performance under a range of physiologically relevant conditions. We generated detailed time-resolved experimental data to evaluate the ability of our model to describe the dynamics of C. elegans reproduction. We find considerable heterogeneity in responses of individual animals to heat stress, which can be understood as modulation of a few processes and may represent a strategy for coping with the ever-changing environment. Our experimental results and model provide quantitative insight into the breakdown of a robust biological system under stress and suggest, surprisingly, that the behavior of complex biological systems may be determined by a small number of key components.</p

In vivo binding of active heat shock transcription factor 1 to human chromosome 9 heterochromatin during stress

Activation of the mammalian heat shock transcription factor (HSF)1 by stress is a multistep process resulting in the transcription of heat shock genes. Coincident with these events is the rapid and reversible redistribution of HSF1 to discrete nuclear structures termed HSF1 granules, whose function is still unknown. Key features are that the number of granules correlates with cell ploidy, suggesting the existence of a chromosomal target. Here we show that in humans, HSF1 granules localize to the 9q11-q12 heterochromatic region. Within this locus, HSF1 binds through direct DNA–protein interaction with a nucleosome-containing subclass of satellite III repeats. HSF1 granule formation only requires the DNA binding competence and the trimerization of the factor. This is the first example of a transcriptional activator that accumulates transiently and reversibly on a chromosome-specific heterochromatic locus

Serotonergic signalling suppresses ataxin 3 aggregation and neurotoxicity in animal models of Machado-Joseph disease

Polyglutamine diseases are a class of dominantly inherited neurodegenerative disorders for which there is no effective treatment. Here we provide evidence that activation of serotonergic signalling is beneficial in animal models of Machado-Joseph disease. We identified citalopram, a selective serotonin reuptake inhibitor, in a small molecule screen of FDA-approved drugs that rescued neuronal dysfunction and reduced aggregation using a Caenorhabditis elegans model of mutant ataxin 3-induced neurotoxicity. MOD-5, the C. elegans orthologue of the serotonin transporter and cellular target of citalopram, and the serotonin receptors SER-1 and SER-4 were strong genetic modifiers of ataxin 3 neurotoxicity and necessary for therapeutic efficacy. Moreover, chronic treatment of CMVMJD135 mice with citalopram significantly reduced ataxin 3 neuronal inclusions and astrogliosis, rescued diminished body weight and strikingly ameliorated motor symptoms. These results suggest that small molecule modulation of serotonergic signalling represents a promising therapeutic target for Machado-Joseph disease.This work was supported by Fundação para a Ciência e Tecnologia (FCT) and COMPETE through the projects ‘[PTDC/SAU-GMG/112617/2009] (to P.M.) and [EXPL/ BIM-MEC/0239/2012] (to A.T.C.)’, by National Ataxia foundation (to P.M.), by Ataxia UK (to P.M.), by National Institutes of Health (NIH) ‘[GM038109, GM081192, AG026647, and NS047331] (to R.I.M.)’, by The Chicago Biomedical Consortium (to R.I.M.) and by the Ellison Medical Foundation (to R.I.M.). A.T.C., A.J., S.E., L.S.S., C.B., S.D.S., A.S.F. and A.N.C. were supported by the FCT individual fellowships SFRH/BPD/79469/2011, SFRH/BD/76613/2011, SFRH/BD/78554/2011, SFRH/BD/ 84650/2012, SFRH/BPD/74452/2010, SFRH/BD/78388/ 2011, SFRH/BPD/91562/2012 and SFRH/BD/51059/2010, respectively. FCT fellowships are co-financed by POPH, QREN, Governo da República Portuguesa and EU/FSE.info:eu-repo/semantics/publishedVersio

Ramucirumab in elderly patients with hepatocellular carcinoma and elevated alpha-fetoprotein after sorafenib in REACH and REACH-2

Background & Aims: Limited data on treatment of elderly patients with hepatocellular carcinoma (HCC) increase the unmet need. REACH and REACH‐2 were global phase III studies of ramucirumab in patients with HCC after prior sorafenib, where patients with alpha‐fetoprotein (AFP) ≥400 ng/mL showed an overall ssurvival (OS) benefit for ramucirumab. These post‐hoc analyses examined efficacy and safety of ramucirumab in patients with HCC and baseline AFP ≥ 400 ng/mL by three prespecified age subgroups (<65, ≥65 to <75 and ≥75 years). Methods: Individual patient data were pooled from REACH (baseline AFP ≥400 ng/mL) and REACH‐2. Kaplan‐Meier and Cox proportional hazards regression methods (stratified by study) assessed OS, progression‐free survival (PFS), time to progression (TTP) and patient‐reported outcomes (Functional Hepatobiliary System Index‐8 [FHSI‐8] score). Results: A total of 542 patients (<65 years: n = 302; ≥65 to <75 years: n = 160; ≥75 years: n = 80) showed similar baseline characteristics between ramucirumab and placebo. Older subgroups had higher hepatitis C and steatohepatitis incidences, and lower AFP levels, than the <65 years subgroup. Ramucirumab prolonged OS in patients <65 years (hazard ratio [HR], 0.753; 95% CI 0.581‐0.975), ≥65 to <75 years (0.602; 0.419‐0.866) and ≥75 years (0.709; 0.420‐1.199), PFS and TTP irrespective of age. Ramucirumab showed similar overall safety profiles across subgroups, with a consistent median relative dose intensity ≥97.8%. A trend towards a delay in symptom deterioration in FHSI‐8 with ramucirumab was observed in all subgroups. Conclusions: In this post‐hoc analysis, ramucirumab showed a survival benefit across age subgroups with a tolerable safety profile, supporting its use in advanced HCC with elevated AFP, irrespective of age, including ≥75 years