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Low complexity (LC) head domains 92 and 108 residues in length are, respectively, required for assembly of neurofilament light (NFL) and desmin intermediate filaments (IFs). As studied in isolation, these IF head domains interconvert between states of conformational disorder and labile, β-strand-enriched polymers. Solid-state NMR (ss-NMR) spectroscopic studies of NFL and desmin head domain polymers reveal spectral patterns consistent with structural order. A combination of intein chemistry and segmental isotope labeling allowed preparation of fully assembled NFL and desmin IFs that could also be studied by ss-NMR. Assembled IFs revealed spectra overlapping with those observed for β-strand-enriched polymers formed from the isolated NFL and desmin head domains. Phosphorylation and disease-causing mutations reciprocally alter NFL and desmin head domain self-association yet commonly impede IF assembly. These observations show how facultative structural assembly of LC domains via labile, β-strand-enriched self-interactions may broadly influence cell morphology.

The coiled-coil domains of intermediate filament (IF) proteins are flanked by regions of low sequence complexity. Whereas IF coiled-coil domains assume dimeric and tetrameric conformations on their own, maturation of eight tetramers into cylindrical IFs is dependent on either "head" or "tail" domains of low sequence complexity. Here we confirm that the tail domain required for assembly of Drosophila Tm1-I/C IFs functions by forming labile cross-β interactions. These interactions are seen in polymers made from the tail domain alone, as well as in assembled IFs formed by the intact Tm1-I/C protein. The ability to visualize such interactions in situ within the context of a discrete cellular assembly lends support to the concept that equivalent interactions may be used in organizing other dynamic aspects of cell morphology.

Simple Summary: Nutritional assessment indicators have been recognized as useful in predicting treatment-related adverse events. In maintenance therapy with PARP inhibitors in ovarian cancer, treatment discontinuation due to treatment-related adverse events has been reported, but factors predicting these events are not identified. Our study suggested that PNI and mGPS can predict the risk of treatment discontinuation due to PARP inhibitor-related adverse events before starting maintenance therapy. This insight opens avenues for more personalized treatment plans, potentially improving patient outcomes. Background: Nutritional status is an important factor influencing toxicity of treatment. Nutritional assessment indicators such as the Prognostic Nutritional Index (PNI), Controlling Nutritional Status (CONUT) score and modified Glasgow Prognostic Score (mGPS) have been reported to be associated with treatment-related adverse events (AEs) for various malignancies. However, there are no reports investigating the relationship between nutritional status and AEs from poly-(ADP-ribose) polymerase (PARP) inhibitors (PARPi), which are widely used in recent years as maintenance therapy for ovarian cancer. Objective: The primary objective was to investigate the usefulness of nutritional assessment indicators in predicting treatment discontinuation due to AEs from PARPi. Methods: This multicenter retrospective study included patients diagnosed with ovarian cancer who received maintenance therapy with PARPi from January 2018 to December 2023. PNI, CONUT score, and mGPS were calculated based on hematological parameters measured within 7 days before the start of PARPi therapy. Results: A total of 272 patients received maintenance therapy with PARPi during the period, but due to the absence of the blood collection of albumin levels within one week or other exclusion criteria, 71 patients were finally included in this analysis. AEs were seen in 59 patients (83.1%), including 25 (35.2%) severe events (grade ≥3 in Common Terminology Criteria for Adverse Events v5.0). Eighteen patients (25.4%) discontinued treatment due to PARPi-related AEs. Low PNI (<48.44) and high mGPS (≥1) were predictors of treatment discontinuation in both univariate and multivariate analyses. CONUT was not a significant predictor in this study. Conclusions: Our study suggested that PNI and mGPS can predict the risk of treatment discontinuation due to PARPi-related AEs before starting maintenance therapy. This insight opens avenues for more personalized treatment plans, potentially improving patient outcomes. [ABSTRACT FROM AUTHOR]

The tropomyosin 1 isoform I/C C‐terminal domain (Tm1‐LC) fibril structure is studied jointly with cryogenic electron microscopy (cryo‐EM) and solid state nuclear magnetic resonance (NMR). This study demonstrates the complementary nature of these two structural biology techniques. Chemical shift assignments from solid state NMR are used to determine the secondary structure at the level of individual amino acids, which is faithfully seen in cryo‐EM reconstructions. Additionally, solid state NMR demonstrates that the region not observed in the reconstructed cryo‐EM density is primarily in a highly mobile random coil conformation rather than adopting multiple rigid conformations. Overall, this study illustrates the benefit of investigations combining cryo‐EM and solid state NMR to investigate protein fibril structure. [ABSTRACT FROM AUTHOR]

Human genetic studies have given evidence of familial, disease-causing mutations in the analogous amino acid residue shared by three related RNA binding proteins causative of three neurological diseases. Alteration of aspartic acid residue 290 of hnRNPA2 to valine is believed to predispose patients to multisystem proteinopathy. Mutation of aspartic acid 262 of hnRNPA1 to either valine or asparagine has been linked to either amyotrophic lateral sclerosis or multisystem proteinopathy. Mutation of aspartic acid 378 of hnRNPDL to either asparagine or histidine has been associated with limb girdle muscular dystrophy. All three of these aspartic acid residues map to evolutionarily conserved regions of low-complexity (LC) sequence that may function in states of either intrinsic disorder or labile self-association. Here, we present a combination of solid-state NMR spectroscopy with segmental isotope labeling and electron microscopy on the LC domain of the hnRNPA2 protein. We show that, for both the wild-type protein and the aspartic acid 290-to-valine mutant, labile polymers are formed in which the LC domain associates into an in-register cross-β conformation. Aspartic acid 290 is shown to be charged at physiological pH and immobilized within the polymer core. Polymers of the aspartic acid 290-to-valine mutant are thermodynamically more stable than wild-type polymers. These observations give evidence that removal of destabilizing electrostatic interactions may be responsible for the increased propensity of the mutated LC domains to self-associate in disease-causing conformations.

Polymerization and phase separation of proteins containing low-complexity (LC) domains are important factors in gene expression, mRNA processing and trafficking, and localization of translation. We have used solid-state nuclear magnetic resonance methods to characterize the molecular structure of self-assembling fibrils formed by the LC domain of the fused in sarcoma (FUS) RNA-binding protein. From the 214-residue LC domain of FUS (FUS-LC), a segment of only 57 residues forms the fibril core, while other segments remain dynamically disordered. Unlike pathogenic amyloid fibrils, FUS-LC fibrils lack hydrophobic interactions within the core and are not polymorphic at the molecular structural level. Phosphorylation of core-forming residues by DNA-dependent protein kinase blocks binding of soluble FUS-LC to FUS-LC hydrogels and dissolves phase-separated, liquid-like FUS-LC droplets. These studies offer a structural basis for understanding LC domain self-assembly, phase separation, and regulation by post-translational modification.

To reveal the structural mechanism by which the low‐complexity domain of the fused in sarcoma protein (FUS‐LC) mediates liquid–liquid phase separation (LLPS), we conducted a vacuum‐ultraviolet circular dichroism (VUV‐CD) spectroscopic study, a technique to analyze the secondary structures of proteins. The VUV‐CD measurements were performed at the BL12 VUV‐CD station at the Hiroshima Synchrotron Radiation Center (HiSOR) in Japan. CD spectra were measured between 180 and 260 nm while controlling the temperature of samples from 37°C to 5°C to obtain the LLPS of FUS‐LC. The CD spectrum obtained at 37°C exhibited a large negative peak at 195 nm and a small negative shoulder near 220 nm. The peak intensity around 195 nm decreased as the sample temperature decreased. The spectral changes originated from the LLPS formation. [ABSTRACT FROM AUTHOR]

A longstanding mystery has been the absence of cytoplasmic intermediate filaments (IFs) from Drosophila despite their importance in other organisms. In the course of characterizing the in vivo expression and functions of Drosophila Tropomyosin (Tm) isoforms, we discovered an essential but unusual product of the Tm1 locus, Tm1-I/C, which resembles an IF protein in some respects. Like IFs, Tm1-I/C spontaneously forms filaments in vitro that are intermediate in diameter between F-actin and microtubules. Like IFs but unlike canonical Tms, Tm1-I/C contains N- and C-terminal low-complexity domains flanking a central coiled coil. In vivo, Tm1-I/C forms cytoplasmic filaments that do not associate with F-actin or canonical Tms. Tm1-I/C is essential for collective border cell migration, in epithelial cells for proper cytoarchitecture, and in the germline for the formation of germ plasm. These results suggest that flies have evolved a distinctive type of cytoskeletal filament from Tm.

Byline: Takahiro. Kato, Masato. Kato, Kimihiro. Takemasa, Masao. Murakami Purpose: To quantitatively evaluate how much the doses to organs at risk are affected in the prone position compared to the [...]

Herein, a science‐based uranium and plutonium mixed oxide (MOX) property model is derived for determining the properties of MOX fuel and analyzing their performance as functions of Pu content, minor‐actinide content, oxygen‐to‐metal ratio, and temperature. The property model is constructed by evaluating the effect of phonons and electronic defects on the heat capacity and thermal conductivity of MOX fuels. The effect of phonons was evaluated based on experimental datasets related to lattice parameters, thermal expansion, and sound speeds. Moreover, the effect of electronic defects was determined by analyzing oxygen‐potential data based on defect chemistry. Furthermore, the model evaluated the effect of the Bredig transition on the thermal properties of MOX fuel by analyzing the irradiation test results. The derived property model is applied to the performance code to analyze fast reactor fuel pins. [ABSTRACT FROM AUTHOR]

Abstract Objective Few studies have reported the influence of clinical background factors on the outcome of Helicobacter pylori eradication therapy in primary care practice. We aimed to determine which clinical background factors influence the outcome of eradication therapy in a primary care setting. Methods This was a retrospective study of patients who received H pylori eradication therapy at Higashiohmi City Gamo Medical Center, Shiga, Japan, from January 2012 to December 2015. We investigated clinical background factors associated with success, failure, and self‐interruption of H pylori eradication therapy: patients’ age, gender, first‐ or second‐line treatment, reasons for receiving gastroenterological endoscopic examination, method of drug administration, and attending physicians’ age and their specialties. Results There were 369 patients (208 females, 161 male), with a mean age of 59 years (range 30‐88 years). The middle‐aged group (50‐69 years) was associated with successful eradication therapy compared with the young group (30‐49 years). The elderly group (>70 years) was associated with eradication therapy failure compared with the middle‐aged group. The young group was associated with self‐interruption of eradication therapy. There was a marginally significant association between male patients and self‐interruption. Older attending physicians (>50 years) were also associated with failure compared with younger physicians. There was no difference in outcome of eradication therapy between generalists and gastroenterology specialists. Conclusion We have identified clinical factors associated with success, failure, and self‐interruption of H pylori eradication therapy in a primary care setting.