Protein phase separation drives the assembly of membraneless organelles, but little is known about how these membraneless organelles are maintained in a metastable liquid- or gel-like phase rather ...than proceeding to solid aggregation. Here, we find that human small heat-shock protein 27 (Hsp27), a canonical chaperone that localizes to stress granules (SGs), prevents FUS from undergoing liquid-liquid phase separation (LLPS) via weak interactions with the FUS low complexity (LC) domain. Remarkably, stress-induced phosphorylation of Hsp27 alters its activity, leading Hsp27 to partition with FUS LC to preserve the liquid phase against amyloid fibril formation. NMR spectroscopy demonstrates that Hsp27 uses distinct structural mechanisms for both functions. Our work reveals a fine-tuned regulation of Hsp27 for chaperoning FUS into either a polydispersed state or a LLPS state and suggests an essential role for Hsp27 in stabilizing the dynamic phase of stress granules.
Amyloid aggregation of phosphorylated Tau (pTau) into neurofibrillary tangles is closely associated with Alzheimer’s disease (AD). Several molecular chaperones have been reported to bind Tau and ...impede its pathological aggregation. Recent findings of elevated levels of Hsp27 in the brains of patients with AD suggested its important role in pTau pathology. However, the molecular mechanism of Hsp27 in pTau aggregation remains poorly understood. Here, we show that Hsp27 partially co-localizes with pTau tangles in the brains of patients with AD. Notably, phosphorylation of Tau by microtubule affinity regulating kinase 2 (MARK2), dramatically enhances the binding affinity of Hsp27 to Tau. Moreover, Hsp27 efficiently prevents pTau fibrillation in vitro and mitigates neuropathology of pTau aggregation in a
Drosophila
tauopathy model. Further mechanistic study reveals that Hsp27 employs its N-terminal domain to directly interact with multiple phosphorylation sites of pTau for specific binding. Our work provides the structural basis for the specific recognition of Hsp27 to pathogenic pTau, and highlights the important role of Hsp27 in preventing abnormal aggregation and pathology of pTau in AD.
Many human neurodegenerative diseases are associated with amyloid fibril formation. Inhibition of amyloid formation is of importance for therapeutics of the related diseases. However, the development ...of selective potent amyloid inhibitors remains challenging. Here based on the structures of amyloid β (Aβ) fibrils and their amyloid-forming segments, we designed a series of peptide inhibitors using RosettaDesign. We further utilized a chemical scaffold to constrain the designed peptides into β-strand conformation, which significantly improves the potency of the inhibitors against Aβ aggregation and toxicity. Furthermore, we show that by targeting different Aβ segments, the designed peptide inhibitors can selectively recognize different species of Aβ. Our study developed an approach that combines the structure-based rational design with chemical modification for the development of amyloid inhibitors, which could be applied to the development of therapeutics for different amyloid-related diseases.
Tau hyper-phosphorylation and deposition into neurofibrillary tangles have been found in brains of patients with Alzheimer's disease (AD) and other tauopathies. Molecular chaperones are involved in ...regulating the pathological aggregation of phosphorylated Tau (pTau) and modulating disease progression. Here, we report that nicotinamide mononucleotide adenylyltransferase (NMNAT), a well-known NAD
synthase, serves as a chaperone of pTau to prevent its amyloid aggregation in vitro as well as mitigate its pathology in a fly tauopathy model. By combining NMR spectroscopy, crystallography, single-molecule and computational approaches, we revealed that NMNAT adopts its enzymatic pocket to specifically bind the phosphorylated sites of pTau, which can be competitively disrupted by the enzymatic substrates of NMNAT. Moreover, we found that NMNAT serves as a co-chaperone of Hsp90 for the specific recognition of pTau over Tau. Our work uncovers a dedicated chaperone of pTau and suggests NMNAT as a key node between NAD
metabolism and Tau homeostasis in aging and neurodegeneration.
The intrinsically disordered protein, Tau, is abundant in neurons and contributes to the regulation of the microtubule (MT) and actin network, while its intracellular abnormal aggregation is closely ...associated with Alzheimer's disease. Here, using in-cell Nuclear Magnetic Resonance (NMR) spectroscopy, we investigated the conformations of two different isoforms of Tau, Tau40 and k19, in mammalian cells. Combined with immunofluorescence imaging and western blot analyses, we found that the isotope-enriched Tau, which was delivered into the cultured mammalian cells by electroporation, is partially colocalized with MT and actin filaments (F-actin). We acquired the NMR spectrum of Tau in human embryonic kidney 293 (HEK-293T) cells, and compared it with the NMR spectra of Tau added with MT, F-actin, and a variety of crowding agents, respectively. We found that the NMR spectrum of Tau in complex with MT best recapitulates the in-cell NMR spectrum of Tau, suggesting that Tau predominantly binds to MT at its MT-binding repeats in HEK-293T cells. Moreover, we found that disease-associated phosphorylation of Tau was immediately eliminated once phosphorylated Tau was delivered into HEK-293T cells, implying a potential cellular protection mechanism under stressful conditions. Collectively, the results of our study reveal that Tau utilizes its MT-binding repeats to bind MT in mammalian cells and highlight the potential of using in-cell NMR to study protein structures at the residue level in mammalian cells.
Acid mine drainage (AMD), arising from mineral resource exploitation, has transformed into a significant global environmental issue for the mining sector, posing considerable risks to water, soil, ...ecosystems, and human health. In this study, the current status and cutting-edge dynamics of AMD remediation research were evaluated using a bibliometrics approach. Publications on AMD remediation were collected from the Web of Science Core Collection (WOSCC) database, and the relevant literature was analyzed quantitatively using various statistical methods, including keyword co-occurrence and burst analysis. In total, 2743 articles related to AMD remediation published from 1990 to 2023 were obtained. The number of publications tended to increase annually, with a relatively fast rate of increase in recent years. Recent research related to AMD remediation has mainly focused on the ecological risks, the environmental geochemical cycling, the application of sulfate-reducing bacteria and adsorption, and the recovery of heavy metals (HMs) and rare earth elements (REEs). It is anticipated that these topics of AMD remediation research are expected to be at the forefront of future research endeavors. In addition, the current status, advantages, and challenges of AMD remediation technologies are discussed from both active and passive management perspectives, providing a theoretical basis and reference for AMD remediation.
Wastewater-based epidemiology (WBE) evaluates the health status, environmental exposure, and lifestyle habits of community inhabitants through the investigation of chemical or biological markers ...present in urban wastewater systems. This approach is frequently employed in discerning drug abuse, disease prevalence, and the presence of environmental contaminants. To comprehend the current state and developmental trajectories in WBE research, the current study utilizes the source literature of the Web of Science Core Collection (WOSCC) database. Implementing the Bibliometrix toolkit in R language and employing CiteSpace and VOSviewer for bibliometric analysis, this investigative pursuit effectuates an all-encompassing evaluation of the WBE literature, traversing a substantial time span of 16 years, encompassing 2008 through 2023. The results of this bibliometric analysis illuminate annual propensities and disciplinary distribution related to WBE research, while discerning the most impactful and prolific contributors, including authors, institutions, countries, and scholarly journals. The onset of the COVID-19 pandemic has engendered the expedited progression of WBE, leading to a substantial escalation in research endeavors in the past three years. By meticulously evaluating highly-cited publications, co-occurrence network of keywords, and keyword burst analysis, it is concluded that the research hotspots in this field focus on the monitoring of illicit drugs, psychoactive substances, and viruses in sewage. Subsequent investigations possess the capacity to propel the advancement of emerging methodologies for biomarker identification and analytical techniques. By concurrently integrating big data technologies (including artificial intelligence and cloud computing) with epidemiological and clinical data sets, a more expansive, precise, and efficacious rendition of WBE research can be realized.
Porous hollow CeO
2
microspheres were fabricated using negative-charged PS microspheres as templates by a facile method. The hollow CeO
2
microspheres were characterized by X-ray diffraction (XRD), ...Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and N
2
adsorption–desorption. The results showed that the as-synthesized hollow CeO
2
microspheres are well monodisperse and uniform in size. The porous shells of hollow microspheres are relatively rough and composed of tiny nanoparticles. The external diameter, internal diameter, and shell thickness of hollow CeO
2
microspheres are about 190, 160, and 15 nm, respectively. A possible mechanism for the formation of hollow CeO
2
spheres was also discussed.
To improve their chemical mechanical polishing (CMP) performance, composite polystyrene-core ceria-shell (PS/CeO
2) abrasives were synthesized by in-situ chemical precipitation. The as-synthesized ...PS/CeO
2 composite microspheres samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and zeta potential analysis. Oxide CMP performance of the PS/CeO
2 composite abrasives was investigated by atomic force microscopy (AFM). The results indicate that PS/CeO
2 composite abrasives with a core–shell structure are obtained successfully. The particle size of as-prepared PS/CeO
2 composite particles is about 140
nm, and the PS microspheres are uniformly coated by CeO
2 nanoparticles. The surface of thermal oxide film polished by PS/CeO
2 composite abrasives has lower topographical variations and surface roughness than that polished by CeO
2 nanoparticles. After polished by composite abrasives, root-mean-square roughness of wafer within 5
μm
×
5
μm area is 0.331
nm, and material removal rate can reach 484.5
nm/min.
•Cu/Fe/Kovar composites have a much better thermal conductivity than Kovar alloys.•Good thermal conductivity of Cu/Fe/Kovar composites is attributed to the formation of Cu network.•Fe interlayer ...decreases the mutual diffusion between Cu coating and Kovar alloy matrix.
To improve the thermal conductivities of Kovar alloys (4J50), Fe and Cu coatings were prepared on surfaces of one of Kovar alloys (4J50) powders by electroless plating and Cu/Fe/Kovar composites were hot-pressing sintered. The Fe interlayer is prepared to decrease the mutual diffusion between the Cu coating and the Kovar alloy matrix. Since the existence of Cu network in the composites, the composites present a better thermal conductivity than Kovar alloys. The Cu/Fe/Kovar composites containing 10 wt% and 20 wt% Cu have a thermal conductivity of 24.7 W/(m·K) and 25.8 W/(m·K), respectively, which is 48 % and 54 % higher than that of the Kovar alloy (16.7 W/(m·K)). Due to the presence of Cu network, the coefficients of thermal expansion of the composites is slightly higher than that of the Kovar alloy. The method reported in this study can be also applied to improve the thermal conductively of other Kovar alloys.
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