Monitoring Early-Stage Protein Aggregation by an Aggregation-Induced Emission Fluorogen

Highly ordered protein aggregates, termed amyloid fibrils, are associated with a broad range of diseases, many of which are neurodegenerative, for example, Alzheimer\u27s and Parkinson\u27s. The transition from soluble, functional protein into insoluble amyloid fibril occurs via a complex process involving the initial generation of highly dynamic early stage aggregates or prefibrillar species. Amyloid probes, for example, thioflavin T and Congo red, have been used for decades as the gold standard for detecting amyloid fibrils in solution and tissue sections. However, these well-established dyes do not detect the presence of prefibrillar species formed during the early stages of protein aggregation. Prefibillar species have been proposed to play a key role in the cytotoxicity of amyloid fibrils and the pathogenesis of neurodegenerative diseases. Herein, we report a novel fluorescent dye (bis(triphenylphosphonium) tetraphenylethene (TPE-TPP)) with aggregation-induced emission characteristics for monitoring the aggregation process of amyloid fibrils. An increase in TPE-TPP fluorescence intensity is observed only with ordered protein aggregation, such as amyloid fibril formation, and not with stable molten globules states or amorphously aggregating species. Importantly, TPE-TPP can detect the presence of prefibrillar species formed early during fibril formation. TPE-TPP exhibits a distinctive spectral shift in the presence of prefibrillar species, indicating a unique structural feature of these intermediates. Using fluorescence polarization, which reflects the mobility of the emitting entity, the specific oligomeric pathways undertaken by various proteins during fibrillation could be discerned. Furthermore, we demonstrate the broad applicability of TPE-TPP to monitor amyloid fibril aggregation, including under diverse conditions such as at acidic pH and elevated temperature, or in the presence of amyloid inhibitors

Modest Declines in Proteome Quality Impair Hematopoietic Stem Cell Self-Renewal.

Low protein synthesis is a feature of somatic stem cells that promotes regeneration in multiple tissues. Modest increases in protein synthesis impair stem cell function, but the mechanisms by which this occurs are largely unknown. We determine that low protein synthesis within hematopoietic stem cells (HSCs) is associated with elevated proteome quality in vivo. HSCs contain less misfolded and unfolded proteins than myeloid progenitors. Increases in protein synthesis cause HSCs to accumulate misfolded and unfolded proteins. To test how proteome quality affects HSCs, we examine Aarssti/sti mice that harbor a tRNA editing defect that increases amino acid misincorporation. Aarssti/sti mice exhibit reduced HSC numbers, increased proliferation, and diminished serial reconstituting activity. Misfolded proteins overwhelm the proteasome within Aarssti/sti HSCs, which is associated with increased c-Myc abundance. Deletion of one Myc allele partially rescues serial reconstitution defects in Aarssti/sti HSCs. Thus, HSCs are dependent on low protein synthesis to maintain proteostasis, which promotes their self-renewal

Discrimination of homocysteine, cysteine and glutathione using an aggregation-induced-emission-active hemicyanine dye

Elevated levels of homocysteine (Hcy) in blood are indicative of many high risk cardiovascular and neurodegenerative diseases. Thus, development of highly efficient and selective dyes for monitoring Hcy levels has attracted much attention. This paper reports the utilization of TPE-Cy, an aggregation-induced-emission active hemicyanine dye, as a probe for the detection of Hcy. More interestingly, this dye shows high selectivity to Hcy over cysteine, glutathione and other amino acids in weakly basic buffer solution

The habitual characteristic of smart phone use under relevant cues among Chinese college students

Excessive smartphone use may be habitual behavior induced by cues associated with the phone. Habitual behavior occurs outside of awareness and is characterized by lack of control. It is not like problematic smartphone use (PSU) (Brand et al., 2016), which is used to either limit behavior or produce pleasure and relieve feelings of pain, stress, and failure despite significant harmful consequences. 62 college students participated in experiments to test the effects of visual cues and self-control, which are the important characteristic of habitual behavior in smartphone-related behavior. The results showed that a significantly larger amount of cue-related phone use behavior occurred in the setting where participants (a) had their smartphones in sight and (b) were given no instructions to exert self-control, compared to when neither of the two conditions was imposed. The habitual model is a useful framework for understanding PSU and can help people avoid it with less stress. The results provide substantial implications for reducing the frequency and duration of smartphone use among college populations

In vivo imaging of patients with chronic pruritus of unknown origin reveals partial sweat duct obstruction with partial itch resolution upon retinoid treatment

BackgroundChronic pruritus of unknown origin (CPUO) is poorly understood and lacks effective treatment options.ObjectivesWe aimed to elucidate abnormalities in the sweat apparatus of patients with CPUO, and to assess efficacy and safety of treatment with systemic retinoids.MethodsAn initial case–control study included 20 affected patients and five healthy controls, for whom heat and sweating were induced, either through a standardized exercise protocol or ingestion of hot water. In vivo high-definition optical coherence tomography, whole-body starch-iodine testing, and skin biopsy for immunofluorescence staining were done to evaluate for sweat duct obstruction. A subsequent retrospective cohort analysis included 56 patients with CPUO, seen at an Itch subspecialty clinic of a single tertiary referral centre, who failed conventional treatments and were treated with isotretinoin and/or acitretin from May 2014 to November 2020. Treatment response to retinoids was defined as a sustained reduction in itch score of ≥2/10. Safety was assessed by proportion stopping treatment due to side effects.ResultsIn vivo imaging in 19 (95%) patients revealed features of partial keratinaceous sweat duct obstruction with statistically significant luminal dilatation compared to controls. Immunofluorescence studies of three patients’ paired lesional/non-lesional biopsies revealed dermcidin accumulation within sweat glands coupled with dermcidin leakage in itchy skin. Fifty-six patients (mean [SD] age 55.2 [17.5] years, 69.6% male) were treated with systemic retinoids. Mean (SD) duration of itch was 116.3 (140.4) months and mean (SD) itch score was 8.2 (1.8). Forty-one (73.2%) initially received isotretinoin, and 15 (26.8%) acitretin. At three months, mean itch score reduced by 2.38 (95% CI -3.2 to −1.6, p < 0.0001). Thirty-eight (67.9%) had a sustained response. Eight (14.81%) achieved an itch score of 0 or 1, with four stopping treatment for a mean (SD) of 318.5 (291.2) days without relapse. Eight (14.3%) stopped or switched retinoid due to adverse effects, with similar incidences between both retinoids, the commonest being dryness.ConclusionBased on novel findings from physiological imaging studies identifying partial keratinaceous sweat duct obstruction in CPUO, we instituted systemic retinoid treatment to address the underlying pathology. In patients who failed conventional therapies, the treatment appears effective and safe

Volatility of mixed atmospheric humic-like substances and ammonium sulfate particles

The volatility of organic aerosols remains poorly understood due to the complexity of speciation and multiphase processes. In this study, we extracted humic-like substances (HULIS) from four atmospheric aerosol samples collected at the SORPES station in Nanjing, eastern China, and investigated the volatility behavior of particles at different sizes using a Volatility Tandem Differential Mobility Analyzer (VTDMA). In spite of the large differences in particle mass concentrations, the extracted HULIS from the four samples all revealed very high-oxidation states (O : C > 0.95), indicating secondary formation as the major source of HULIS in Yangtze River Delta (YRD). An overall low volatility was identified for the extracted HULIS, with the volume fraction remaining (VFR) higher than 55% for all the regenerated HULIS particles at the temperature of 280 degrees C. A kinetic mass transfer model was applied to the thermodenuder (TD) data to interpret the observed evaporation pattern of HULIS, and to derive the mass fractions of semi-volatile (SVOC), low-volatility (LVOC) and extremely low-volatility components (ELVOC). The results showed that LVOC and ELVOC dominated (more than 80 %) the total volume of HULIS. Atomizing processes led to a size-dependent evaporation of regenerated HULIS particles, and resulted in more ELVOC in smaller particles. In order to understand the role of interaction between inorganic salts and atmospheric organic mixtures in the volatility of an organic aerosol, the evaporation of mixed samples of ammonium sulfate (AS) and HULIS was measured. The results showed a significant but nonlinear influence of ammonium sulfate on the volatility of HULIS. The estimated fraction of ELVOC in the organic part of the largest particles (145 nm) increased from 26 %, in pure HULIS samples, to 93% in 1 : 3 (mass ratio of HULIS : AS) mixed samples, to 45% in 2 : 2 mixed samples, and to 70% in 3 : 1 mixed samples, suggesting that the interaction with ammonium sulfate tends to decrease the volatility of atmospheric organic compounds. Our results demonstrate that HULIS are important low-volatility, or even extremely low-volatility, compounds in the organic-aerosol phase. As important formation pathways of atmospheric HULIS, multiphase processes, including oxidation, oligomerization, polymerization and interaction with inorganic salts, are indicated to be important sources of low-volatility and extremely low-volatility species of organic aerosols.Peer reviewe

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead