NF‐κB/NKILA signaling modulates the anti‐cancerous effects of EZH2 inhibition

A wealth of evidence supports the broad therapeutic potential of NF‐κB and EZH2 inhibitors as adjuvants for breast cancer treatment. We contribute to this knowledge by elucidating, for the first time, unique regulatory crosstalk between EZH2, NF‐κB and the NF‐κB interacting long non‐coding RNA (NKILA). We define a novel signaling loop encompassing canonical and non‐canonical actions of EZH2 on the regulation of NF‐κB/NKILA homeostasis, with relevance to breast cancer treatment. We applied a respective silencing approach in non‐transformed breast epithelial cells, triple negative MDA‐MB‐231 cells and hormone responsive MCF‐7 cells, and measured changes in EZH2/NF‐κB/NKILA levels to confirm their interdependence. We demonstrate cell line‐specific fluctuations in these factors that functionally contribute to epithelial‐to‐mesenchymal transition (EMT) remodelling and cell fate response. EZH2 inhibition attenuates MDA‐MB‐231 cell motility and CDK4‐mediated MCF‐7 cell cycle regulation, while inducing global H3K27 methylation and an EMT phenotype in non‐transformed cells. Notably, these events are mediated by a cell‐context dependent gain or loss of NKILA and NF‐κB. Depletion of NF‐κB in non‐transformed cells enhances their sensitivity to growth factor signaling and suggests a role for the host microenvironment milieu in regulating EZH2/NF‐κB/NKILA homeostasis. Taken together, this knowledge critically informs the delivery and assessment of EZH2 inhibitors in breast cancer.     

DNMTs are required for delayed genome instability caused by radiation

The ability of ionizing radiation to initiate genomic instability has been harnessed in the clinic where the localized delivery of controlled doses of radiation is used to induce cell death in tumor cells. Though very effective as a therapy, tumor relapse can occur in vivo and its appearance has been attributed to the radio-resistance of cells with stem cell-like features. The molecular mechanisms underlying these phenomena are unclear but there is evidence suggesting an inverse correlation between radiation-induced genomic instability and global hypomethylation. To further investigate the relationship between DNA hypomethylation, radiosensitivity and genomic stability in stem-like cells we have studied mouse embryonic stem cells containing differing levels of DNA methylation due to the presence or absence of DNA methyltransferases. Unexpectedly, we found that global levels of methylation do not determine radiosensitivity. In particular, radiation-induced delayed genomic instability was observed at the Hprt gene locus only in wild-type cells. Furthermore, absence of Dnmt1 resulted in a 10-fold increase in de novo Hprt mutation rate, which was unaltered by radiation. Our data indicate that functional DNMTs are required for radiation-induced genomic instability, and that individual DNMTs play distinct roles in genome stability. We propose that DNMTS may contribute to the acquirement of radio-resistance in stem-like cells.     

α-synuclein levels affect autophagosome numbers in vivo and modulate Huntington disease pathology

Huntington and Parkinson diseases (HD and PD) are two major neurodegenerative disorders pathologically characterized by the accumulation of the aggregate-prone proteins mutant huntingtin (in HD) and α-synuclein (in PD). Mutant huntingtin is an autophagy substrate and autophagy modulators affect HD pathology both in vitro and in vivo. In vitro, α-synuclein levels are able to modulate autophagy: α-synuclein overexpression inhibits autophagy, whereas downregulation promotes autophagy. Here, we review our recent studies showing that α-synuclein levels modulate mutant huntingtin toxicity in mouse models. This phenotypic modification is accompanied by the in vivo modulation of autophagosome numbers in mouse brains from both control and HD mice expressing different levels of α-synuclein.     

Presence of Blastocystis in gut microbiota is associated with cognitive traits and decreased executive function

Growing evidence implicates the gut microbiome in cognition. Blastocystis is a common gut single-cell eukaryote parasite frequently detected in humans but its potential involvement in human pathophysiology has been poorly characterized. Here we describe how the presence of Blastocystis in the gut microbiome was associated with deficits in executive function and altered gut bacterial composition in a discovery (n = 114) and replication cohorts (n = 942). We also found that Blastocystis was linked to bacterial functions related to aromatic amino acids metabolism and folate-mediated pyrimidine and one-carbon metabolism. Blastocystis-associated shifts in bacterial functionality translated into the circulating metabolome. Finally, we evaluated the effects of microbiota transplantation. Donor’s Blastocystis subtypes led to altered recipient’s mice cognitive function and prefrontal cortex gene expression. In summary, Blastocystis warrant further consideration as a novel actor in the gut microbiome-brain axis.Subject terms: Biomarkers, Pathogenesis, Diagnosis     

Phosphate limitation as crucial factor to enhance yeast lipid production from short‐chain fatty acids

Microbial lipids for chemical synthesis are commonly obtained from sugar‐based substrates which in most cases is not economically viable. As a low‐cost carbon source, short‐chain fatty acids (SCFAs) that can be obtained from food wastes offer an interesting alternative for achieving an affordable lipid production process. In this study, SCFAs were employed to accumulate lipids using Yarrowia lipolytica ACA DC 50109. For this purpose, different amounts of SCFAs, sulfate, phosphate and carbon: phosphate ratios were used in both synthetic and real SCFAs‐rich media. Although sulfate limitation did not increase lipid accumulation, phosphate limitation was proved to be an optimal strategy for increasing lipid content and lipid yields in both synthetic and real media, reaching a lipid productivity up to 8.95 g/L h. Remarkably, the highest lipid yield (0.30 g/g) was achieved under phosphate absence condition (0 g/L). This fact demonstrated the suitability of using low‐phosphate concentrations to boost lipid production from SCFAs.

Microbial lipids for chemical synthesis are commonly obtained from sugar‐based substrates which in most cases is not economically viable. As a low‐cost carbon source, short‐chain fatty acids (SCFAs) that can be obtained from food‐wastes offer an interesting alternative for achieving an affordable lipid production process. In this study, SCFAs were employed to accumulate lipids using Yarrowia lipolytica ACA DC 50109.     

Chronic inhibition of the mitochondrial ATP synthase in skeletal muscle triggers sarcoplasmic reticulum distress and tubular aggregates

Tubular aggregates (TA) are honeycomb-like arrays of sarcoplasmic-reticulum (SR) tubules affecting aged glycolytic fibers of male individuals and inducing severe sarcomere disorganization and muscular pain. TA develop in skeletal muscle from Tubular Aggregate Myopathy (TAM) patients as well as in other disorders including endocrine syndromes, diabetes, and ageing, being their primary cause unknown. Nowadays, there is no cure for TA. Intriguingly, both hypoxia and calcium dyshomeostasis prompt TA formation, pointing to a possible role for mitochondria in their setting. However, a functional link between mitochondrial dysfunctions and TA remains unknown. Herein, we investigate the alteration in muscle-proteome of TAM patients, the molecular mechanism of TA onset and a potential therapy in a preclinical mouse model of the disease. We show that in vivo chronic inhibition of the mitochondrial ATP synthase in muscle causes TA. Upon long-term restrained oxidative phosphorylation (OXPHOS), oxidative soleus experiments a metabolic and structural switch towards glycolytic fibers, increases mitochondrial fission, and activates mitophagy to recycle damaged mitochondria. TA result from the overresponse of the fission controller DRP1, that upregulates the Store-Operate-Calcium-Entry and increases the mitochondria-SR interaction in a futile attempt to buffer calcium overloads upon prolonged OXPHOS inhibition. Accordingly, hypoxic muscles cultured ex vivo show an increase in mitochondria/SR contact sites and autophagic/mitophagic zones, where TA clusters grow around defective mitochondria. Moreover, hypoxia triggered a stronger TA formation upon ATP synthase inhibition, and this effect was reduced by the DRP1 inhibitor mDIVI. Remarkably, the muscle proteome of TAM patients displays similar alterations in mitochondrial dynamics and in ATP synthase contents. In vivo edaravone treatment in mice with restrained OXPHOS restored a healthy phenotype by prompting mitogenesis and mitochondrial fusion. Altogether, our data provide a functional link between the ATP synthase/DRP1 axis and the setting of TA, and repurpose edaravone as a possible treatment for TA-associated disorders.Subject terms: Musculoskeletal abnormalities, Energy metabolism