The lysine-specific histone demethylase 1A (LSD1) also known as lysine (K)-specific demethylase 1A (KDM1A) is a central epigenetic regulator of metabolic reprogramming in obesity-associated diseases, neurological disorders, and cancer. Here, we evaluated the ability of oleacein, a biophenol secoiridoid naturally present in extra virgin olive oil (EVOO), to target LSD1. Molecular docking and dynamic simulation approaches revealed that oleacein could target the binding site of the LSD1 cofactor flavin adenosine dinucleotide with high affinity and at low concentrations. At higher concentrations, oleacein was predicted to target the interaction of LSD1 with histone H3 and the LSD1 co-repressor (RCOR1/CoREST), likely disturbing the anchorage of LSD1 to chromatin. AlphaScreen-based in vitro assays confirmed the ability of oleacein to act as a direct inhibitor of recombinant LSD1, with an IC50 as low as 2.5 μmol/L. Further, oleacein fully suppressed the expression of the transcription factor SOX2 (SEX determining Region Y-box 2) in cancer stem-like and induced pluripotent stem (iPS) cells, which specifically occurs under the control of an LSD1-targeted distal enhancer. Conversely, oleacein failed to modify ectopic SOX2 overexpression driven by a constitutive promoter. Overall, our findings provide the first evidence that EVOO contains a naturally occurring phenolic inhibitor of LSD1, and support the use of oleacein as a template to design new secoiridoid-based LSD1 inhibitors.

The SCN5A gene encodes the α-subunit of the voltage-gated cardiac sodium channel (NaV1.5), a key player in cardiac action potential depolarization. Genetic variants in protein-coding regions of the human SCN5A have been largely associated with inherited cardiac arrhythmias. Increasing evidence also suggests that aberrant expression of the SCN5A gene could increase susceptibility to arrhythmogenic diseases, but the mechanisms governing SCN5A expression are not yet well understood. To gain insights into the molecular basis of SCN5A gene regulation, we used rat gastrocnemius muscle four days following denervation, a process well known to stimulate Scn5a expression. Our results show that denervation of rat skeletal muscle induces the expression of the adult cardiac Scn5a isoform. RNA-seq experiments reveal that denervation leads to significant changes in the transcriptome, with Scn5a amongst the fifty top upregulated genes. Consistent with this increase in expression, ChIP-qPCR assays show enrichment of H3K27ac and H3K4me3 and binding of the transcription factor Gata4 near the Scn5a promoter region. Also, Gata4 mRNA levels are significantly induced upon denervation. Genome-wide analysis of H3K27ac by ChIP-seq suggest that a super enhancer recently described to regulate Scn5a in cardiac tissue is activated in response to denervation. Altogether, our experiments reveal that similar mechanisms regulate the expression of Scn5a in denervated muscle and cardiac tissue, suggesting a conserved pathway for SCN5A expression among striated muscles.

Voltage-gated sodium (Na V ) channels are transmembrane proteins that initiate and propagate neuronal and cardiac action potentials. Na V channel β subunits have been widely studied due to their modulatory role. Mice null for Scn1b , which encodes Na V β1 and β1b subunits, have defects in neuronal development and excitability, spontaneous generalized seizures, cardiac arrhythmias, and early mortality. A mutation in exon 3 of SCN1B , c.308A>T leading to β1_p.D103V and β1b_p.D103V, was previously found in a patient with a history of proarrhythmic conditions with progressive atrial standstill as well as cognitive and motor deficits accompanying structural brain abnormalities. We investigated whether β1 or β1b subunits carrying this mutation affect Na V 1.5 and/or Na V 1.1 currents using a whole cell patch-clamp technique in tsA201 cells. We observed a decrease in sodium current density in cells co-expressing Na V 1.5 or Na V 1.1 and β1 D103V compared to β1 WT . Interestingly, β1b D103V did not affect Na V 1.1 sodium current density but induced a positive shift in the voltage dependence of inactivation and a faster recovery from inactivation compared to β1b WT . The β1b D103V isoform did not affect Na V 1.5 current properties. Although the SCN1B _c.308A>T mutation may not be the sole cause of the patient’s symptoms, we observed a clear loss of function in both cardiac and brain sodium channels. Our results suggest that the mutant β1 and β1b subunits play a fundamental role in the observed electrical dysfunction.