The purpose of this study was to determine the prognostic role of ten eleven translocation (TET) family proteins and DNA glycosylase (TDG) in patients with early breast cancer (EBC).
Expression of ...mRNAs encoding TET1-3 and TDG in 162 breast cancer tissues was quantified using real-time polymerase chain reaction analysis. The general characteristics of patients and clinicopathologic factors were collected. Estimation of patient survival was calculated using the Kaplan-Meier method, and independent prognostic indicators were analyzed using Cox regression analysis.
The level of TET1 mRNA was significantly related to overall survival (OS) (P = 0.022). Multivariate analysis shows that the TNM stage was an independent predictor of disease-free survival (DFS) (HR = 1.761, 95% CI: 1.124-2.761, P = 0.014) and OS (HR = 2.135, 95% CI: 1.070-4.263, P = 0.032). Further, in patients with EBC who were treated with anthracyclines, Kaplan-Meier analysis indicates that the levels of TET3 and TDG mRNAs were related to DFS (P = 0.026 and 0.030, respectively), and multivariate analysis reveals that high levels of TET3 (HR = 1.944, 95% CI: 1.029-3.672, P = 0.040) and TDG (HR = 2.178, 95% CI: 1.140-4.163, P = 0.018) mRNAs were independent indicators of favorable DFS.
Our study indicates that EBC patients with decreased expression of TET1 mRNA had worse OS and that the levels of TET3 and TDG mRNAs were independent prognostic factors for patients who received anthracycline chemotherapy.
Yeast ataxin-2, also known as Pbp1, senses the activity state of mitochondria in order to regulate TORC1. A domain of Pbp1 required to adapt cells to mitochondrial activity is of low sequence ...complexity. The low-complexity (LC) domain of Pbp1 forms labile, cross-β polymers that facilitate phase transition of the protein into liquid-like or gel-like states. Phase transition for other LC domains is reliant upon widely distributed aromatic amino acids. In place of tyrosine or phenylalanine residues prototypically used for phase separation, Pbp1 contains 24 similarly disposed methionine residues. Here, we show that the Pbp1 methionine residues are sensitive to hydrogen peroxide (H2O2)-mediated oxidation in vitro and in living cells. Methionine oxidation melts Pbp1 liquid-like droplets in a manner reversed by methionine sulfoxide reductase enzymes. These observations explain how reversible formation of labile polymers by the Pbp1 LC domain enables the protein to function as a sensor of cellular redox state.
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•Phase separation of the yeast ataxin-2 methionine-rich LC domain is sensitive to H2O2•The dissolved droplets are specifically revived by methionine sulfoxide reductases•Methionine to tyrosine variants confer resistance to H2O2in vitro and in cells•Yeast ataxin-2 senses cellular redox state to modulate TORC1 activity
Many proteins that are able to undergo phase transitions contain repeats rich in hydrophobic residues. By contrast, yeast ataxin-2 condensates rely on an abundance of methionines, providing a means for redox-sensitive regulation of its material properties.
Pbp1 (poly(A)-binding protein-binding protein 1) is a cytoplasmic stress granule marker that is capable of forming condensates that function in the negative regulation of TORC1 signaling under ...respiratory conditions. Polyglutamine expansions in its mammalian ortholog ataxin-2 lead to spinocerebellar dysfunction due to toxic protein aggregation. Here, we show that loss of Pbp1 in S. cerevisiae leads to decreased amounts of mRNAs and mitochondrial proteins which are targets of Puf3, a member of the PUF (Pumilio and FBF) family of RNA-binding proteins. We found that Pbp1 supports the translation of Puf3-target mRNAs in respiratory conditions, such as those involved in the assembly of cytochrome c oxidase and subunits of mitochondrial ribosomes. We further show that Pbp1 and Puf3 interact through their respective low complexity domains, which is required for Puf3-target mRNA translation. Our findings reveal a key role for Pbp1-containing assemblies in enabling the translation of mRNAs critical for mitochondrial biogenesis and respiration. They may further explain prior associations of Pbp1/ataxin-2 with RNA, stress granule biology, mitochondrial function, and neuronal health.
Background
Acute cholecystitis (AC) is a common surgical emergency. The Tokyo Guidelines 2018 (TG18) provides a reliable algorithm for the treatment of AC patients to achieve optimal outcomes. ...However, the economic benefits have not been validated. We hypothesize that good outcomes and cost savings can both be achieved if patients are treated according to the TG18.
Method
This retrospective study included 275 patients who underwent cholecystectomy in a 15-month span. Patients were divided into three groups (group 1: mild AC; group 2: moderate AC with American Society of Anesthesiologists (ASA) physical status class ≤ 2 and Charlson Comorbidity Index (CCI) score ≤ 5; and group 3: moderate AC with ASA class ≥ 3, CCI score ≥ 6, or severe AC). Each group was further divided into two subgroups according to management (followed or deviated from the TG18). Patient demographics, clinical outcomes, and hospital costs were compared.
Results
For group 1 patients, 77 (81%) were treated according to the TG18 and had a significantly higher successful laparoscopic cholecystectomy (LC) rate (100%), lower hospital cost ($1896 vs $2388), and shorter hospital stay (2.9 vs 8 days) than those whose treatment deviated from the TG18. For group 2 patients, 50 (67%) were treated according to the TG18 and had a significantly lower hospital cost ($1926 vs $2856), shorter hospital stay (3.9 vs 9.9 days), and lower complication rate (0% vs 12.5%). For group 3 patients, 62 (58%) were treated according to the TG18 and had a significantly lower intensive care unit (ICU) admission rate (9.7% vs 25%), but a longer hospital stay (12.6 vs 7.8 days). However, their hospital costs were similar. Early LC in group 3 patients did not have economic benefits over gallbladder drainage and delayed LC.
Conclusion
The TG18 are the state-of-the-art guidelines for the treatment of AC, achieving both satisfactory outcomes and cost-effectiveness.
The NADase SARM1 is a central switch in injury-activated axon degeneration, an early hallmark of many neurological diseases. Here, we present cryo-electron microscopy (cryo-EM) structures of ...autoinhibited (3.3 Å) and active SARM1 (6.8 Å) and provide mechanistic insight into the tight regulation of SARM1’s function by the local metabolic environment. Although both states retain an octameric core, the defining feature of the autoinhibited state is a lock between the autoinhibitory Armadillo/HEAT motif (ARM) and catalytic Toll/interleukin-1 receptor (TIR) domains, which traps SARM1 in an inactive state. Mutations that break this lock activate SARM1, resulting in catastrophic neuronal death. Notably, the mutants cannot be further activated by the endogenous activator nicotinamide mononucleotide (NMN), and active SARM1 is product inhibited by Nicotinamide (NAM), highlighting SARM1’s functional dependence on key metabolites in the NAD salvage pathway. Our studies provide a molecular understanding of SARM1’s transition from an autoinhibited to an injury-activated state and lay the foundation for future SARM1-based therapies to treat axonopathies.
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•Autoinhibited (3.3 Å) and active (6.8 Å) structures of pro-degenerative NADase SARM1 solved•Identification of a critical autoinhibitory lock•Lock mutations convert inactive SARM1 to an active, neurotoxic state•Enzymatic studies explain SARM1’s functional dependence on local metabolic environment
Bratkowski et al. describe cryo-EM structures of autoinhibited and active SARM1, an axon-enriched, injury-activated NADase. Structure-function studies elucidate the mode of autoinhibition and SARM1 activity regulation. The authors provide mechanistic insight into SARM1’s regulation by the local metabolic environment, laying the foundation for future SARM1-based therapies to treat neurological diseases.
Yeast ataxin-2, also known as Pbp1 (polyA binding protein-binding protein 1), is an intrinsically disordered protein implicated in stress granule formation, RNA biology, and neurodegenerative ...disease. To understand the endogenous function of this protein, we identify Pbp1 as a dedicated regulator of TORC1 signaling and autophagy under conditions that require mitochondrial respiration. Pbp1 binds to TORC1 specifically during respiratory growth, but utilizes an additional methionine-rich, low complexity (LC) region to inhibit TORC1. This LC region causes phase separation, forms reversible fibrils, and enables self-association into assemblies required for TORC1 inhibition. Mutants that weaken phase separation in vitro exhibit reduced capacity to inhibit TORC1 and induce autophagy. Loss of Pbp1 leads to mitochondrial dysfunction and reduced fitness during nutritional stress. Thus, Pbp1 forms a condensate in response to respiratory status to regulate TORC1 signaling.
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•Pbp1 is a negative regulator of TORC1 required during respiratory growth•A methionine-rich low complexity region of Pbp1 mediates formation of a condensate•Mutations that weaken phase separation in vitro compromise TORC1 inhibition in vivo•Loss of Pbp1 function leads to mitochondrial dysfunction and reduced survivability
Unpacking the role of yeast ataxin-2 reveals that it preserves mitochondrial homeostasis, undergoing a condition-sensitive phase transition to modulate TORC1 function.
Aggregate-like biomolecular assemblies are emerging as new conformational states with functionality. Aire, a transcription factor essential for central T cell tolerance, forms large aggregate-like ...assemblies visualized as nuclear foci. Here we demonstrate that Aire utilizes its caspase activation recruitment domain (CARD) to form filamentous homo-multimers in vitro, and this assembly mediates foci formation and transcriptional activity. However, CARD-mediated multimerization also makes Aire susceptible to interaction with promyelocytic leukemia protein (PML) bodies, sites of many nuclear processes including protein quality control of nuclear aggregates. Several loss-of-function Aire mutants, including those causing autoimmune polyendocrine syndrome type-1, form foci with increased PML body association. Directing Aire to PML bodies impairs the transcriptional activity of Aire, while dispersing PML bodies with a viral antagonist restores this activity. Our study thus reveals a new regulatory role of PML bodies in Aire function, and highlights the interplay between nuclear aggregate-like assemblies and PML-mediated protein quality control.
Akt is a protein serine/threonine kinase that is involved in the regulation of diverse cellular processes. Phosphorylation of Akt at regulatory residues Thr-308 and Ser-473 leads to its full ...activation. The protein phosphatase 2A (PP2A) has long been known to negatively regulate Akt activity. The PP2A holoenzyme consists of the structural subunit (A), catalytic subunit (C), and a variable regulatory subunit (B). Here we report the identification of the specific B regulatory subunit that targets the PP2A holoenzyme to Akt. We found endogenous association of PP2A AB55C holoenzymes with Akt by co-immunoprecipitation analyses in pro-lymphoid FL5.12 cells. Akt was shown to associate with ectopically expressed B55α subunit in NIH3T3 cells. The direct interaction between B55α subunit and Akt was confirmed using in vitro pulldown analyses. Intriguingly, we found that overexpression of B55α subunit significantly impaired phosphorylation at Thr-308, but to a lesser extent at Ser-473 of Akt in both FL5.12 and NIH3T3 cells. Concomitantly, phosphorylation of a subset of Akt substrates, including FoxO3a, was substantially decreased by B55α overexpression in these cells. Silencing of B55α expression markedly increased phosphorylation at Thr-308 but not at Ser-473 in both FL5.12 cells and NIH3T3 cells. Consistently, PP2A AB55αC holoenzymes preferentially dephosphorylated phospho-Thr-308 rather than phospho-Ser-473 in in vitro dephosphorylation assays. Furthermore, B55α overexpression retarded proliferation of NIH3T3 cells, and knockdown of B55α expression increased survival of FL5.12 cells upon interleukin-3 deprivation. Together, our data demonstrate that B55α-dependent targeting of the PP2A holoenzyme to Akt selectively regulates Akt phosphorylation at Thr-308 to regulate cell proliferation and survival.
Pfu DNA polymerase is a vital enzyme in PCR‐related experiments. However, it is not easy to achieve high‐level expression and high purity through one‐step purification. This paper illustrates the ...method to acquire the full‐length open reading frame of Pfu DNA polymerase. Without altering its amino acids, we have modified the codon usage, based on that of the enhanced green fluorescence protein (eGFP), and named it rPfu. The synthesized rPfu gene has been subcloned into the pET28a plasmid and expressed in four Escherichia coli strains without the pLysS plasmid. Three strains have expressed a high level of soluble Pfu DNA polymerase. With the aid of Ni‐NTA His•Bind® resin, we could obtain high purity (>95%) soluble recombinant protein. Compared with the commercial, proofreading DNA polymerase, rPfu’s bioactivity was 12,987 U/mg; that is, 88,311 U of rPfu could be obtained from 50 mL cultured E. coli. The purified rPfu was able to amplify the length of DNA fragments at least 5.5 kb. The method of increasing soluble protein's yield using the eGFP codon usage may introduce a new possibility to the expression of other soluble recombinant proteins.
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In Taiwan, lung cancers occur predominantly in never-smokers, of whom nearly 60% have stage IV disease at diagnosis. We aimed to assess the efficacy of low-dose CT (LDCT) screening among ...never-smokers, who had other risk factors for lung cancer.
The Taiwan Lung Cancer Screening in Never-Smoker Trial (TALENT) was a nationwide, multicentre, prospective cohort study done at 17 tertiary medical centres in Taiwan. Eligible individuals had negative chest radiography, were aged 55-75 years, had never smoked or had smoked fewer than 10 pack-years and stopped smoking for more than 15 years (self-report), and had one of the following risk factors: a family history of lung cancer; passive smoke exposure; a history of pulmonary tuberculosis or chronic obstructive pulmonary disorders; a cooking index of 110 or higher; or cooking without using ventilation. Eligible participants underwent LDCT at baseline, then annually for 2 years, and then every 2 years up to 6 years thereafter, with follow-up assessments at each LDCT scan (ie, total follow-up of 8 years). A positive scan was defined as a solid or part-solid nodule larger than 6 mm in mean diameter or a pure ground-glass nodule larger than 5 mm in mean diameter. Lung cancer was diagnosed through invasive procedures, such as image-guided aspiration or biopsy or surgery. Here, we report the results of 1-year follow-up after LDCT screening at baseline. The primary outcome was lung cancer detection rate. The p value for detection rates was estimated by the χ
test. Univariate and multivariable logistic regression analyses were used to assess the association between lung cancer incidence and each risk factor. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of LDCT screening were also assessed. This study is registered with ClinicalTrials.gov, NCT02611570, and is ongoing.
Between Dec 1, 2015, and July 31, 2019, 12 011 participants (8868 females) were enrolled, of whom 6009 had a family history of lung cancer. Among 12 011 LDCT scans done at baseline, 2094 (17·4%) were positive. Lung cancer was diagnosed in 318 (2·6%) of 12 011 participants (257 2·1% participants had invasive lung cancer and 61 0·5% had adenocarcinomas in situ). 317 of 318 participants had adenocarcinoma and 246 (77·4%) of 318 had stage I disease. The prevalence of invasive lung cancer was higher among participants with a family history of lung cancer (161 2·7% of 6009 participants) than in those without (96 1·6% of 6002 participants). In participants with a family history of lung cancer, the detection rate of invasive lung cancer increased significantly with age, whereas the detection rate of adenocarcinoma in situ remained stable. In multivariable analysis, female sex, a family history of lung cancer, and age older than 60 years were associated with an increased risk of lung cancer and invasive lung cancer; passive smoke exposure, cumulative exposure to cooking, cooking without ventilation, and a previous history of chronic lung diseases were not associated with lung cancer, even after stratification by family history of lung cancer. In participants with a family history of lung cancer, the higher the number of first-degree relatives affected, the higher the risk of lung cancer; participants whose mother or sibling had lung cancer were also at an increased risk. A positive LDCT scan had 92·1% sensitivity, 84·6% specificity, a PPV of 14·0%, and a NPV of 99·7% for lung cancer diagnosis.
TALENT had a high invasive lung cancer detection rate at 1 year after baseline LDCT scan. Overdiagnosis could have occurred, especially in participants diagnosed with adenocarcinoma in situ. In individuals who do not smoke, our findings suggest that a family history of lung cancer among first-degree relatives significantly increases the risk of lung cancer as well as the rate of invasive lung cancer with increasing age. Further research on risk factors for lung cancer in this population is needed, particularly for those without a family history of lung cancer.
Ministry of Health and Welfare of Taiwan.
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