Effect of proliferating cell nuclear antigen ubiquitination and chromatin structure on the dynamic properties of the Y-family DNA polymerases

Y-family DNA polymerases carry out translesion synthesis past damaged DNA. DNA polymerases (pol) η and ι are usually uniformly distributed through the nucleus but accumulate in replication foci during S phase. DNA-damaging treatments result in an increase in S phase cells containing polymerase foci. Using photobleaching techniques, we show that polη is highly mobile in human fibroblasts. Even when localized in replication foci, it is only transiently immobilized. Although ubiquitination of proliferating cell nuclear antigen (PCNA) is not required for the localization of polη in foci, it results in an increased residence time in foci. polι is even more mobile than polη, both when uniformly distributed and when localized in foci. Kinetic modeling suggests that both polη and polι diffuse through the cell but that they are transiently immobilized for ∼150 ms, with a larger proportion of polη than polι immobilized at any time. Treatment of cells with DRAQ5, which results in temporary opening of the chromatin structure, causes a dramatic immobilization of polη but not polι. Our data are consistent with a model in which the polymerases are transiently probing the DNA/chromatin. When DNA is exposed at replication forks, the polymerase residence times increase, and this is further facilitated by the ubiquitination of PCNA

Cerebrospinal fluid phospho-tau T217 outperforms T181 as a biomarker for the differential diagnosis of Alzheimer\u27s disease and PET amyloid-positive patient identification

BACKGROUND: Cerebrospinal fluid biomarker profiles characterized by decreased amyloid-beta peptide levels and increased total and phosphorylated tau levels at threonine 181 (pT181) are currently used to discriminate between Alzheimer\u27s disease and other neurodegenerative diseases. However, these changes are not entirely specific to Alzheimer\u27s disease, and it is noteworthy that other phosphorylated isoforms of tau, possibly more specific for the disease process, have been described in the brain parenchyma of patients. The precise detection of these isoforms in biological fluids remains however a challenge. METHODS: In the present study, we used the latest quantitative mass spectrometry approach, which achieves a sensitive detection in cerebrospinal fluid biomarker of two phosphorylated tau isoforms, pT181 and pT217, and first analyzed a cohort of probable Alzheimer\u27s disease patients and patients with other neurological disorders, including tauopathies, and a set of cognitively normal controls. We then checked the validity of our results on a second cohort comprising cognitively normal individuals and patients with mild cognitive impairments and AD stratified in terms of their amyloid status based on PiB-PET imaging methods. RESULTS: In the first cohort, pT217 but not pT181 differentiated between Alzheimer\u27s disease patients and those with other neurodegenerative diseases and control subjects much more specificity and sensitivity than pT181. T217 phosphorylation was increased by 6.0-fold in patients with Alzheimer\u27s disease whereas T181 phosphorylation was only increased by 1.3-fold, when compared with control subjects. These results were confirmed in the case of a second cohort, in which the pT217 cerebrospinal fluid levels marked out amyloid-positive patients with a sensitivity and a specificity of more than 90% (AUC 0.961; CI 0.874 to 0.995). The pT217 concentrations were also highly correlated with the PiB-PET values (correlation coefficient 0.72; P \u3c 0.001). CONCLUSIONS: Increased cerebrospinal fluid pT217 levels, more than those of pT181, are highly specific biomarkers for detecting both the preclinical and advanced forms of Alzheimer\u27s disease. This finding should greatly improve the diagnosis of Alzheimer\u27s disease, along with the correlations found to exist between pT217 levels and PiB-PET data. It also suggests that pT217 is a promising potential target for therapeutic applications and that a link exists between amyloid and tau pathology

Influence of the live cell DNA marker DRAQ5 on chromatin-associated processes

In the last decade, live cell fluorescence microscopy experiments have revolutionized cellular and molecular biology, enabling the localization of proteins within cellular compartments to be analysed and to determine kinetic parameters of enzymatic reactions in living nuclei to be measured. Recently, in vivo DNA labelling by DNA-stains such as DRAQ5, has provided the opportunity to measure kinetic reactions of GFP-fused proteins in targeted areas of the nucleus with different chromatin compaction levels. To verify the suitability of combining DRAQ5-staining with protein dynamic measurements, we have tested the cellular consequences of DRAQ5 DNA intercalation. We show that DRAQ5 intercalation rapidly modifies both the localization and the mobility properties of several DNA-binding proteins such as histones, DNA repair, replication and transcription factors, by stimulating a release of these proteins from their substrate. Most importantly, the effect of DRAQ5 on the mobility of essential cellular enzymes results in a potent inhibition of the corresponding cellular functions. From these observations, we suggest that great caution must be used when interpreting live cell data obtained using DRAQ5

Distinct Streptococcus pneumoniae cause invasive disease in Papua New Guinea

Streptococcus pneumoniae is a key contributor to childhood morbidity and mortality in Papua New Guinea (PNG). For the first time, whole genome sequencing of 174 isolates has enabled detailed characterisation of diverse S. pneumoniae causing invasive disease in young children in PNG, 1989-2014. This study captures the baseline S. pneumoniae population prior to the introduction of 13-valent pneumococcal conjugate vaccine (PCV13) into the national childhood immunisation programme in 2014. Relationships amongst lineages, serotypes and antimicrobial resistance traits were characterised, and the population was viewed in the context of a global collection of isolates. The analyses highlighted adiverse S. pneumoniae population associated with invasive disease in PNG, with 45 unique Global Pneumococcal Sequence Clusters (GPSCs) observed amongst the 174 isolates reflecting multiple lineages observed in PNG that have not been identified in other geographic locations. The majority of isolates were from children with meningitis, of which 52% (n=72) expressed non-PCV13 serotypes. Over a third of isolates were predicted to be resistant to at least one antimicrobial. PCV13 serotype isolates had 10.1 times the odds of being multidrug-resistant (MDR) compared to non-vaccine serotype isolates, and no isolates with GPSCs unique to PNG were MDR. Serotype 2 was the most commonly identified serotype; we identified a highly clonal cluster of serotype 2 isolates unique to PNG, and a distinct second cluster indicative of long-distance transmission. Ongoing surveillance, including whole-genome sequencing, is needed to ascertain the impact of the national PCV13 programme upon the S. pneumoniae population, including serotype replacement and antimicrobial resistance traits. © 2022 The Authors

Blood amyloid and tau biomarkers as predictors of cerebrospinal fluid profiles

Blood biomarkers represent a major advance for improving the management, diagnosis, and monitoring of Alzheimer's disease (AD). However, their context of use in relation to routine cerebrospinal fluid (CSF) analysis for the quantification of amyloid peptides and tau proteins remains to be determined. We studied in two independent cohorts, the performance of blood biomarkers in detecting "nonpathological" (A−/T−/N−), amyloid (A+) or neurodegenerative (T+ /N+) CSF profiles. Plasma Aβ/Aβ ratio and phosphorylated tau (p-tau(181)) were independent and complementary predictors of the different CSF profile and in particular of the nonpathological (A−/T−/N−) profile with a sensitivity and specificity close to 85%. These performances and the corresponding biomarker thresholds were significantly different from those related to AD detection. The use of blood biomarkers to identify patients who may benefit from secondary CSF testing represents an attractive stratification strategy in the clinical management of patients visiting memory clinics. This could reduce the need for lumbar puncture and foreshadow the use of blood testing on larger populations. The online version contains supplementary material available at 10.1007/s00702-022-02474-9

Correlations between soluble alpha/beta forms of amyloid precursor protein and Abeta38, 40 and 42 in human cerebrospinal fluid

International audienceCerebrospinal fluid (CSF) biomarkers are now widely used for diagnosis of Alzheimer disease (AD) in atypical clinical forms, for differential and early diagnosis, or for stratification of patients in clinical trials. Among these biomarkers, different forms of amyloid peptides (Aβ) produced by the cleavage of a transmembrane precursor protein called APP (amyloid precursor protein) have a major role. Aβ peptides exist in different length the most common ones having 40 (Aβ40), 42 (Aβ42), or 38 (Aβ38) amino acids in length. APP processing by gamma-secretase releases also an amino-terminal secreted fragment called sAβPP-beta while an alternative nonamyloidogenic cleavage of APP, through an alpha-secretase, liberates another fragment called sAβPP-alpha. To decipher the molecular and pathological mechanisms leading to the production and the detection of these entities is essential for the comprehension and the prevention of AD. In this report, we present the results of the Keywords: Biomarkers CSF Soluble amyloid precursor proteins Aβ fragment peptides Alzheimer disease Dementi

Decreased sAβPPβ, Aβ38, and Aβ40 Cerebrospinal Fluid Levels in Frontotemporal Dementia.

International audienceTo improve the etiological diagnosis of neurodegenerative dementias like Alzheimer's disease (AD) or frontotemporal dementia (FTD), we evaluated the value of individual and combined measurements of the following relevant cerebrospinal fluid (CSF) biomarkers: Tau, 181p-Tau, Aβ38, Aβ40, Aβ42, sAβPPα, and sAβPPβ. This study conducted in two centers included patients with FTD (n = 34), AD (n = 52), as well as a control group of persons without dementia (CTRL, n = 42). Identical clinical criteria and pre-analytical conditions were used while CSF biomarkers were measured using commercial single and multiplex quantitative immunoassays. Thorough statistical analyses, including ROC curves, logistic regressions, and decision trees, were performed. We validated in AD the specific increase of p-Tau levels and the decrease of Aβ42 levels, two biological hallmarks of this disease. Tau concentrations were highest in AD and intermediate in FTD when compared to CTRL. The most interesting results were obtained by focusing on amyloid biomarkers as we found out in FTD a significant decrease of sAβPPβ, Aβ38, and Aβ40 levels. Aβ38 in particular was the most useful biomarker to differentiate FTD subjects from the CTRL population. Combining p-Tau and Aβ38 led us to correctly classifying FTD patients with sensitivity at 85% and specificity at 82%. Significant changes in amyloid biomarkers, particularly for Aβ38, are therefore seen in FTD. This could be quite useful for diagnosis purposes and it might provide additional evidence on the interrelationship between Tau and AβPP biology which understanding is essential to progress towards optimal therapeutic and diagnostic approaches of dementia

Intranasal sufentanil versus intravenous morphine for acute severe trauma pain: A double-blind randomized non-inferiority study.

BACKGROUND: Intravenous morphine (IVM) is the most common strong analgesic used in trauma, but is associated with a clear time limitation related to the need to obtain an access route. The intranasal (IN) route provides easy administration with a fast peak action time due to high vascularization and the absence of first-pass metabolism. We aimed to determine whether IN sufentanil (INS) for patients presenting to an emergency department with acute severe traumatic pain results in a reduction in pain intensity non-inferior to IVM. METHODS AND FINDINGS: In a prospective, randomized, multicenter non-inferiority trial conducted in the emergency departments of 6 hospitals across France, patients were randomized 1:1 to INS titration (0.3 μg/kg and additional doses of 0.15 μg/kg at 10 minutes and 20 minutes if numerical pain rating scale [NRS] > 3) and intravenous placebo, or to IVM (0.1 mg/kg and additional doses of 0.05 mg/kg at 10 minutes and 20 minutes if NRS > 3) and IN placebo. Patients, clinical staff, and research staff were blinded to the treatment allocation. The primary endpoint was the total decrease on NRS at 30 minutes after first administration. The prespecified non-inferiority margin was -1.3 on the NRS. The primary outcome was analyzed per protocol. Adverse events were prospectively recorded during 4 hours. Among the 194 patients enrolled in the emergency department cohort between November 4, 2013, and April 10, 2016, 157 were randomized, and the protocol was correctly administered in 136 (69 IVM group, 67 INS group, per protocol population, 76% men, median age 40 [IQR 29 to 54] years). The mean difference between NRS at first administration and NRS at 30 minutes was -4.1 (97.5% CI -4.6 to -3.6) in the IVM group and -5.2 (97.5% CI -5.7 to -4.6) in the INS group. Non-inferiority was demonstrated (p < 0.001 with 1-sided mean-equivalence t test), as the lower 97.5% confidence interval of 0.29 (97.5% CI 0.29 to 1.93) was above the prespecified margin of -1.3. INS was superior to IVM (intention to treat analysis: p = 0.034), but without a clinically significant difference in mean NRS between groups. Six severe adverse events were observed in the INS group and 2 in the IVM group (number needed to harm: 17), including an apparent imbalance for hypoxemia (3 in the INS group versus 1 in the IVM group) and for bradypnea (2 in the INS group versus 0 in the IVM group). The main limitation of the study was that the choice of concomitant analgesics, when they were used, was left to the discretion of the physician in charge, and co-analgesia was more often used in the IVM group. Moreover, the size of the study did not allow us to conclude with certainty about the safety of INS in emergency settings. CONCLUSIONS: We confirm the non-inferiority of INS compared to IVM for pain reduction at 30 minutes after administration in patients with severe traumatic pain presenting to an emergency department. The IN route, with no need to obtain a venous route, may allow early and effective analgesia in emergency settings and in difficult situations. Confirmation of the safety profile of INS will require further larger studies. TRIAL REGISTRATION: ClinicalTrials.gov NCT02095366. EudraCT 2013-001665-16

Diversification of T Cell Responses to Carboxy-terminal Determinants within the 65-kD Heat-shock Protein Is Involved in Regulation of Autoimmune Arthritis

The T cell response to the 65-kD mycobacterial heat-shock protein (Bhsp65) has been implicated in the pathogenesis of autoimmune arthritis. Adjuvant arthritis (AA) induced in the Lewis rat (RT-1l) by injection of Mycobacterium tuberculosis serves as an experimental model for human rheumatoid arthritis (RA). However, the immunological basis of regulation of acute AA, or of susceptibility/resistance to AA is not known. We have defined the specificity of the proliferative T cell responses to Bhsp65 during the course of AA in the Lewis rat. During the early phase of the disease (6–9 d after onset of AA), Lewis rats raised T cell responses to many determinants within Bhsp65, spread throughout the molecule. Importantly, in the late phase of the disease (8–10 wk after onset of AA), there was evidence for diversification of the T cell responses toward Bhsp65 carboxy-terminal determinants (BCTD) (namely, 417–431, 441–455, 465–479, 513–527, and 521–535). Moreover, arthritic rats in the late phase of AA also raised vigorous T cell responses to those carboxy-terminal determinants within self(rat) hsp65 (Rhsp65) that correspond in position to the above BCTD. These results suggest that the observed diversification is possibly triggered in vivo by induction of self(Rhsp65)-reactive T cells. Interestingly, another strain of rat, the Wistar Kyoto (WKY/NHsd) rat (RT-1l), with the same major histocompatibility complex class II molecules as the Lewis rat, was found to be resistant to AA. In WKY rats, vigorous responses to the BCTD, to which the Lewis rat responded only in the late phase of AA, were observed very early, 10 d after injection of M. tuberculosis. Strikingly, pretreatment with the peptides comprising the set of BCTD, but not its amino-terminal determinants, provided significant protection to naive Lewis rats from subsequent induction of AA. Thus, T cell responses to the BCTD are involved in regulating inflammatory arthritis in the Lewis rat and in conferring resistance to AA in the WKY rat. These results have important implications in understanding the pathogenesis of RA and in devising new immunotherapeutic strategies for this disease