Mitofusin 2 Integrates Mitochondrial Network Remodelling, Mitophagy and the Renewal of Respiratory Chain Proteins in Neurons After Oxygen and Glucose Deprivation.

In the efforts to develop effective therapeutic strategies limiting post-ischemic injury, mitochondria emerge as key element in determining the fate of the neurons. Mitochondrial damage can be alleviated by various mechanisms including mitochondrial network remodelling, mitochondrial elimination and mitochondrial protein biogenesis. However, the mechanisms regulating the relationship between these phenomena are poorly understood. Here we hypothesize that mitofusin 2 (Mfn2), a mitochondrial GTPase, involved in mitochondrial fusion, mitochondria trafficking and mitochondria and endoplasmic reticulum (ER) tethering, may act as a linking and regulatory factor in neurons following ischemic insult. To verify this assumption, we performed a temporal oxygen and glucose deprivation (OGD) on rat cortical primary culture to determine whether Mfn2 protein reduction may affect the onset of mitophagy, subsequent mitochondrial biogenesis and thus neuronal survival. In our study we found that Mfn2 knock-down increased the susceptibility of the neurons to the OGD. Mfn2 protein reduction prevented mitochondrial network remodelling and resulted in the prolonged mitophagosomes formation in response to the insult. Further on, Mfn2 protein reduction was accompanied by a reduced level of Parkin protein and an increased Parkin accumulation with mitochondria. As for Mfn2-expressing neurons, the OGD insult was followed by an elevated mtDNA content and an increase in the respiratory chain proteins. Neither of this phenomena were observed for Mfn2-reduced neurons. Collectively, our findings show that Mfn2 in neurons is involved in their response to mild and transient OGD stress, balancing the extent of elimination of defective mitochondria and positively influencing mitochondrial respiratory proteins levels. Our study confirms that Mfn2 is an essential element of the neuronal response to ischemic insult, necessary for the neuronal survival.

Pharmacological inhibition of LSD1 triggers myeloid differentiation by targeting GSE1 oncogenic functions in AML

The histone demethylase LSD1 is over-expressed in hematological tumors and has emerged as a promising target for anticancer treatment, so that several LSD1 inhibitors are under development and testing, in preclinical and clinical settings. However, the complete understanding of their complex mechanism of action is still unreached. Here, we unraveled a novel mode of action of the LSD1 inhibitors MC2580 and DDP-38003, showing that they can induce differentiation of AML cells through the downregulation of the chromatin protein GSE1. Analysis of the phenotypic effects of GSE1 depletion in NB4 cells showed a strong decrease of cell viability in vitro and of tumor growth in vivo. Mechanistically, we found that a set of genes associated with immune response and cytokine-signaling pathways are upregulated by LSD1 inhibitors through GSE1-protein reduction and that LSD1 and GSE1 colocalize at promoters of a subset of these genes at the basal state, enforcing their transcriptional silencing. Moreover, we show that LSD1 inhibitors lead to the reduced binding of GSE1 to these promoters, activating transcriptional programs that trigger myeloid differentiation. Our study offers new insights into GSE1 as a novel therapeutic target for AML.

Feeding Strategies to Reduce Nutrient Losses and Improve the Sustainability of Growing Pigs

The efficiency of pig production using nutrients has increased over the years. Still, better efficiency of nutrient utilization can be achieved by feeding pigs with diets adjusted to their estimated requirements. An increase in nutrient efficiency of utilization represents economic gains while maximizing environmental performance. The objective of this paper is to review the impact of different methods of diet formulation that provide farm animals with the amount of nutrients to satisfy their needs while minimizing nutrient excretion and greenhouse gas emissions. Diet formulation is one tool that can help to maximize nitrogen and energy utilization by decreasing crude protein content in diets. The use of local feedstuff and non-human-edible products (e.g., canola meal) associated with synthetic amino acid inclusion in the diet are valuable techniques to reduce carbon footprint. Precision feeding and nutrition is another powerful tool that allows not only daily tailoring of diets for maximal nutrient efficiency of utilization but also to reduce costs and improve nitrogen efficiency of utilization. In this review, we simulated through mathematical models the nitrogen and energy efficiency of utilization resulting from crude protein reduction in the diet. An 8% crude protein reduction in the diet can increase nitrogen efficiency of utilization by 54% while costing 11% less than a control diet without synthetic amino acids. The same reduction in crude protein represented a major improvement in available energy due to the decrease of energetic losses linked to protein deamination. Urinary and hindgut fermentation energy losses were 24% lower for pigs fed with low-protein diets when compared to control diets. In terms of modern feeding techniques and strategies, precision feeding and nutrition can decrease nitrogen excretion by 30% when compared to group phase feeding. The benefits of feeding pigs with low-protein diets and precision feeding techniques are additive and might result in a 61% nitrogen efficiency of utilization. There is room for improvement in the way nutrient requirements are estimated in pigs. Improving the understanding of the variation of nutrient utilization among pigs can contribute to further environmental gains.

Assessment of Sacsin Turnover in Patients With ARSACS: Implications for Molecular Diagnosis and Pathogenesis

Background and Objectives:Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is caused by mutations in SACS gene encoding sacsin, a huge multimodular protein of unknown function. More than 200 SACS mutations have been described worldwide to date. Since ARSACS presents phenotypic variability, previous empirical studies attempted to correlate the nature and position of SACS mutations with the age of onset or with disease severity, though not considering the effect of the various mutations on protein stability. In this work, we studied genotype-phenotype correlation in ARSACS at a functional level.Methods:We analyzed a large set of skin fibroblasts derived from ARSACS patients, including both new and already published cases, carrying mutations of different type affecting diverse domains of the protein.Results:We found that sacsin is almost absent in ARSACS patients, regardless of the nature of the mutation. As expected, we did not detect sacsin in patients with truncating mutations. Interestingly, we found it strikingly reduced or absent also in compound heterozygotes carrying diverse missense mutations. In this case, we excluded SACS mRNA decay, defective translation or faster post-translational degradation as possible causes of protein reduction. Conversely, our results demonstrate that nascent mutant sacsin protein undergoes cotranslational ubiquitination and degradation.Discussion:Our results provide one mechanistic explanation for the lack of genotype-phenotype correlation in ARSACS. We also propose a new and unambiguous criterion for ARSACS diagnosis, that is based on the evaluation of sacsin level. Finally, we identified preemptive degradation of a mutant protein as a novel cause of a human disease.

Behavioural and molecular characterisation of the Dlg2 haploinsufficiency rat model of genetic risk for psychiatric disorder

Genetic studies implicate disruption to the DLG2 gene in copy number variants as increasing risk for schizophrenia, autism spectrum disorders and intellectual disability. To investigate psychiatric endophenotypes associated with DLG2 haploinsufficiency (and concomitant PSD-93 protein reduction) a novel clinically relevant Dlg2+/- rat was assessed for abnormalities in anxiety, sensorimotor gating, hedonic reactions, social behaviour, and locomotor response to the N-Methyl-D-aspartic acid receptor antagonist phencyclidine. Dlg gene and protein expression were also investigated to assess model validity. Reductions in PSD-93 messenger RNA and protein were observed in the absence of compensation by other related genes or proteins. Behaviourally Dlg2+/- rats show potentiated locomotor response to phencyclidine, as is typical of psychotic disorder models, in the absence of deficits in the other behavioural phenotypes assessed here. This shows that the behavioural effects of Dlg2 haploinsufficiency may specifically relate to psychosis vulnerability but are subtle, providing a contrast to the gross deficits in Dlg2 homozygous models (Winkler, et al., 2018; Yoo et al., 2020a) which do not so specifically model the single chromosome DLG2 deletion in carriers of risk-associated copy number variants.

Sweet revenge: AtSWEET12 in plant defense against bacterial pathogens by apoplastic sucrose limitation

Depriving bacterial pathogens of sugars is a potential plant defense strategy. The relevance of SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTERS (SWEETs) in plant susceptibility to pathogens has been established, but their role in plant defense remains unknown. We identified Arabidopsis thaliana SWEETs (AtSWEETs) involved in defense against nonhost and host Pseudomonas syringae pathogens through reverse genetic screening of atsweet1-17 mutants. Double/triple mutant, complementation, and overexpression line analysis, and apoplastic sucrose estimation studies revealed that AtSWEET12 suppresses pathogen multiplication by limiting sucrose availability in the apoplast. Localization studies suggested that plant defense occurred via increased plasma membrane targeting of AtSWEET12 with concomitant AtSWEET11 protein reduction. Moreover, the heterooligomerization of AtSWEET11 and AtSWEET12 was involved in regulating sucrose transport. Our results highlight a PAMP-mediated defense strategy against foliar bacterial pathogens whereby plants control AtSWEET11-mediated sucrose efflux in the apoplast through AtSWEET12. We uncover a fascinating new mechanism of pathogen starvation as a broad-spectrum disease resistance mechanism in parallel with existing immune pathways.

Evaluation of Methionine Sources in Protein Reduced Diets for Turkeys in the Late Finishing Period Regarding Performance, Footpad Health and Liver Health

Footpad dermatitis and hepatic lipidosis are health problems in fattening turkeys where a positive influence of higher methionine content in feed is discussed. The effects of the methionine supplements DL-methionine (DLM) and liquid methionine hydroxyl analogue free acid (MHA-FA) under the aspect of low protein diets were investigated in this study based on performance parameters, footpad health, liver health and oxidative stress. In this study, 80 female turkeys (B.U.T. Big 6) of 63 day-old, were randomly assigned to four groups characterising a 2 × 2 factorial design with five replicates each over five weeks. The groups were fed with diets differing in methionine source (DLM vs. MHA-FA, assuming a biological activity of MHA-FA of 65%) and crude protein content (15% vs. 18%) for 35 days. The results showed no significant interactions between the protein content and methionine source. Strong protein reduction significantly impaired water intake, feed intake, weight gain and feed conversation ratio, but improved footpad health. DLM and MHA-FA addition had no significant effect on weight gain, crude fat and protein contents in the liver, but DLM resulted in a significant increase in livers antioxidative capacity compared to MHA-FA. Although the protein reduction resulted in reduced performance, the study showed that MHA-FA can be replaced by DLM in a 100:65 weight ratio without compromising performance but with certain advantages in the antioxidative capacity of the liver.

Nutritional interventions based on dietary restriction and nutrient reductions for the prevention of doxorubicin chemotherapy side effects

BACKGROUND: Doxorubicin (DOX) is one of most used chemotherapeutic drugs, but it has important adverse effects. Nutrition has a critical role to prevent or minimize chemotherapy side effects. Caloric and nutrient restriction has been widely studied in different health fields showing extensive beneficial effects. Given the importance of these interventions, it is expected that some of them have benefits in patients under DOX chemotherap OBJECTIVE: This review aimed to compile published studies evaluating the effects of different dietary intetrventions based on restriction of calories or certain nutrients against DOX-induced damage and toxicity. RESULTS: Caloric restriction and partial reduction of fat have shown to reduce DOX cardiotoxicity correlating with a reduction of oxidative stress. Reduction of dietary fat was proved to act in the same sense at liver and kidney. Studies in relation to protein reduction is more elevated has focused only on kidneys and bone, and under certain circumstances, these interventions could increase susceptibility to DOX toxicity. CONCLUSIONS: The promising effects of restriction of dietary fat, protein and sodium on differerent organs have been supported by a greater number of studies among all the dietary interventions evaluated. Still, clinical studies are necessary to confirm the potential usefulness of these interventions.

Effect of Feeding Low Protein Diets on the Production Traits and the Nitrogen Composition of Excreta of Broiler Chickens

The main goal of the current study was to investigate the effects of feeding low protein (LP) diets on the performance parameters and excreta composition of broiler chickens. In total, 288 male Ross 308 day-old chickens were divided into two dietary treatment groups using six replicate pens with 24 chickens each. No LP diet was fed in the starter phase. The protein reduction in the grower and finisher phases were 1.8% and 2% respectively. Beside the measurements of production traits, on day 24 and 40 representative fresh excreta samples were collected, their dry matter, total N, NH4+-N and uric acid-N contents determined, and the ratio of urinary and fecal N calculated. Dietary treatments failed to cause significant differences in the feed intake, growth rate, and feed conversion ratio of animals. LP diets decreased the total nitrogen and uric acid contents of excreta significantly. The age of birds had also significant effect, resulting more reduction in the grower phase compared with the finisher. The ratio of urinary N was higher at day 40 compared with the age of day 24. The urinary N content of broiler chicken’s excreta is lower than can be found in the literature, which should be considered in the ammonia inventory calculations.