Targeting autophagy as a novel strategy for facilitating the therapeutic action of potentiators on ΔF508 cystic fibrosis transmembrane conductance regulator

Channel activators (potentiators) of cystic fibrosis (CF) transmembrane conductance regulator (CFTR), can be used for the treatment of the small subset of CF patients that carry plasma membrane-resident CFTR mutants. However, approximately 90% of CF patients carry the misfolded ΔF508-CFTR and are poorly responsive to potentiators, because ΔF508-CFTR is intrinsically unstable at the plasma membrane (PM) even if rescued by pharmacological correctors. We have demonstrated that human and mouse CF airways are autophagy deficient due to functional sequestration of BECN1 and that the tissue transglutaminase-2 inhibitor, cystamine, or antioxidants restore BECN1-dependent autophagy and reduce SQSTM1/p62 levels, thus favoring ΔF508-CFTR trafficking to the epithelial surface. Here, we investigated whether these treatments could facilitate the beneficial action of potentiators on ΔF508-CFTR homozygous airways. Cystamine or the superoxide dismutase (SOD)/catalase-mimetic EUK-134 stabilized ΔF508-CFTR at the plasma membrane of airway epithelial cells and sustained the expression of CFTR at the epithelial surface well beyond drug withdrawal, overexpressing BECN1 and depleting SQSTM1. This facilitates the beneficial action of potentiators in controlling inflammation in ex vivo ΔF508-CFTR homozygous human nasal biopsies and in vivo in mouse ΔF508-CFTR lungs. Direct depletion of Sqstm1 by shRNAs in vivo in ΔF508-CFTR mice synergized with potentiators in sustaining surface CFTR expression and suppressing inflammation. Cystamine pre-treatment restored ΔF508-CFTR response to the CFTR potentiators genistein, Vrx-532 or Vrx-770 in freshly isolated brushed nasal epithelial cells from ΔF508-CFTR homozygous patients. These findings delineate a novel therapeutic strategy for the treatment of CF patients with the ΔF508-CFTR mutation in which patients are first treated with cystamine and subsequently pulsed with CFTR potentiators.     

Genetic and environmental heterogeneity of residual variance of weight traits in Nellore beef cattle

Background

Many studies have provided evidence of the existence of genetic heterogeneity of environmental variance, suggesting that it could be exploited to improve robustness and uniformity of livestock by selection. However, little is known about the perspectives of such a selection strategy in beef cattle.

Methods

A two-step approach was applied to study the genetic heterogeneity of residual variance of weight gain from birth to weaning and long-yearling weight in a Nellore beef cattle population. First, an animal model was fitted to the data and second, the influence of additive and environmental effects on the residual variance of these traits was investigated with different models, in which the log squared estimated residuals for each phenotypic record were analyzed using the restricted maximum likelihood method. Monte Carlo simulation was performed to assess the reliability of variance component estimates from the second step and the accuracy of estimated breeding values for residual variation.

Results

The results suggest that both genetic and environmental factors have an effect on the residual variance of weight gain from birth to weaning and long-yearling in Nellore beef cattle and that uniformity of these traits could be improved by selecting for lower residual variance, when considering a large amount of information to predict genetic merit for this criterion. Simulations suggested that using the two-step approach would lead to biased estimates of variance components, such that more adequate methods are needed to study the genetic heterogeneity of residual variance in beef cattle.     

T-DNA tagging in the model legume Medicago truncatula allows efficient gene discovery

The annual legume Medicago truncatula has been proposed as a model plant to study various aspects of legume biology including rhizobial and mycorrhizal symbiosis because it is well suited for the genetic analysis of these processes . To facilitate the characterization of M. truncatula genes participating in various developmental processes we have initiated an insertion mutagenesis program in this plant using three different T-DNAs as tags. To investigate which type of vector is the most suitable for mutagenesis we compared the behavior of these T-DNAs. One T-DNA vector was a derivative of pBin19 and plant selection was based on kanamycin resistance. The two other vectors carried T-DNA conferring Basta resistance in the transgenic plants. For each T-DNA type, we determined the copy number in the transgenic lines, the structure of the T-DNA loci and the sequences of the integration sites. The T-DNA derived from pBin19 generated complex T-DNA insertion patterns. The two others generally gave single copy T-DNA inserts that could result in gene fusions for the pGKB5 T-DNA. Analysis of the T-DNA borders revealed that several M. truncatula genes were tagged in these transgenic lines and in vivo gus fusions were also obtained. These results demonstrate that T-DNA tagging can efficiently be used in M. truncatula for gene discovery.     

Physical activity,dietary intake and quality of life during COVID-19 lockdown in patients awaiting transcatheter aortic valve implantation

BackgroundThe COVID-19 pandemic has led to a national lockdown in the Netherlands, which also affected transcatheter aortic valve implantation (TAVI) patients. The objective of the study was to describe physical activity, dietary intake and quality of life (QoL) in patients on the waiting list for TAVI pre-lockdown and during lockdown.MethodsConsecutive patients awaiting TAVI at the Amsterdam University Medical Centers, the Netherlands were included. Measurements were self-reported effect of lockdown, physical activity, dietary intake and QoL.ResultsIn total, 58 patients (median age 80, interquartile range (IQR) 76–84, 45% female) were observed pre-lockdown and 16 patients (median age 78, IQR 76–82, 25% female) during lockdown. Ten of the 16 patients during lockdown reported a decline in physical activity. However, we observed a median number of 5861 steps a day (IQR 4579–7074) pre-lockdown and 8404 steps a day (IQR 7653–10,829) during lockdown. Median daily protein intake was 69 g (IQR 59–82) pre-lockdown and 90 g (IQR 68–107) during lockdown. Self-rated health on a visual analogue scale was 63 points (IQR 51–74) pre-lockdown and 73 points (IQR 65–86) during lockdown.ConclusionsMore than half of the patients during lockdown reported less physical activity, while we observed a higher number of steps a day, a similar dietary intake and a higher QoL. Therefore, patients on the TAVI waiting list appeared to be able to cope with the lockdown measures.     

In-hospital cardiovascular events after liver transplantation: predictors and long-term outcome

Introduction

Liver transplantation has emerged as a successful therapy for end-stage liver disease. However, cardiovascular mortality is the leading cause of fatality in the postoperative period. The aim of this study was to reveal the prevalence and identify risk factors of early cardiovascular events (CVEs).

Methods

We performed a retrospective study of all consecutive patients who underwent a primary liver transplantation from 1986 to 2017 (n?=?916). We investigated the occurrence of in-hospital CVEs, their predictors, and short- and long-term outcome.

Results

The prevalence of CVEs was 11%. The adjusted analysis showed that higher age (OR 1.06, 95% CI 1.03–1.09), higher MELD score (OR 1.04, 95% CI 1.01–1.07 CI) and sinus tachycardia at time of screening (OR 3.12, 95% CI 1.45–6.72) were positive predictors for a CVE. Preoperative propranolol use showed a trend towards a higher risk of CVE (OR 1.66, 95% CI 1.00–2.77, p?=?0.051). In a sub-analysis of patients where echocardiography data were available (n?=?597), a larger left atrial diameter and a higher E/E′ ratio were related to early CVEs. Ten-year survival in 30-day survivors was favourable (68.6%; 56.0% vs. 69.8% in the CVE+ vs. the CVE-group, respectively, p?=?0.056).

Discussion

In conclusion, besides known risk factors (age and MELD score), sinus tachycardia (related to the presence of acute liver failure and cirrhosis) was an independent predictor for CVE after liver transplantation.

     

Glucose sensing and signalling properties in Saccharomyces cerevisiae require the presence of at least two members of the glucose transporter family.

The kinetics of glucose transport in a number of different mutants of Saccharomyces cerevisiae with multiple deletions in the glucose transporter gene family were determined. The deletions led to differences in maximal rate and affinity for glucose uptake by the cells, dependent on the growth conditions. At the same time, there were changes in glucose repression, as determined by expression of invertase activity. Only in the strain with genes HXT1-4 and SNF3 deleted but carrying HXT6/7 were glucose uptake kinetics and invertase activity independent of the presence or concentration of glucose in the growth medium. Some degree of glucose sensitivity was recovered if the SNF3 or HXT2 gene was present in the multiple-deletion background. It is hypothesized that during growth on glucose, both modulation of the kinetics of glucose uptake and derepression of invertase activity require the presence of more than one active gene of the glucose transporter family.