The Clostridioides difficile Cysteine-Rich Exosporium Morphogenetic Protein, CdeC, Exhibits Self-Assembly Properties That Lead to Organized Inclusion Bodies in Escherichia coli

Indexación: Scopus.Clostridioides difficile is an obligately anaerobic, spore-forming, Grampositive pathogenic bacterium that is considered the leading cause of nosocomial diarrhea worldwide. Recent studies have attempted to understand the biology of the outermost layer of C. difficile spores, the exosporium, which is believed to contribute to early interactions with the host. The fundamental role of the cysteine-rich proteins CdeC and CdeM has been described. However, the molecular details behind the mechanism of exosporium assembly are missing. The underlying mechanisms that govern exosporium assembly in C. difficile remain poorly studied, in part due to difficulties in obtaining pure soluble recombinant proteins of the C. difficile exosporium. In this work, we observed that CdeC was able to form organized inclusion bodies (IBs) in Escherichia coli filled with lamella-like structures separated by an interspace of 5 to 15 nm; however, CdeC expression in an E. coli strain with a more oxidative environment led to the loss of the lamella-like organization of CdeC IBs. Additionally, dithiothreitol (DTT) treatment of CdeC inclusion bodies released monomeric soluble forms of CdeC. Deletions in different portions of CdeC did not affect CdeC's ability to aggregate and form oligomers stable under denaturation conditions but affected CdeC's self-assembly properties. Overall, these observations have important implications in further studies elucidating the role of CdeC in the exosporium assembly of C. difficile spores. IMPORTANCE The endospore of Clostridioides difficile is the vehicle for transmission and persistence of the pathogen, and, specifically, the exosporium is the first contact between the host and the spore. The underlying mechanisms that govern exosporium assembly in C. difficile remain understudied, in part due to difficulties in obtaining pure soluble recombinant proteins of the C. difficile exosporium. Understanding the exosporium assembly's molecular bases may be essential to developing new therapies against C. difficile infection.https://journals.asm.org/doi/epub/10.1128/mSphere.01065-2

The STIM1 inhibitor ML9 disrupts basal autophagy in cardiomyocytes by decreasing lysosome content

Stromal-interaction molecule 1 (STIM1)-mediated store-operated Ca2+ entry (SOCE) plays a key role in mediating cardiomyocyte hypertrophy, both in vitro and in vivo. Moreover, there is growing support for the contribution of SOCE to the Ca2+ overload associated with ischemia/reperfusion injury. Therefore, STIM1 inhibition is proposed as a novel target for controlling both hypertrophy and ischemia/reperfusion-induced Ca2+ overload. Our aim was to evaluate the effect of ML9, a STIM1 inhibitor, on cardiomyocyte viability. ML9 was found to induce cell death in cultured neonatal rat cardiomyocytes. Caspase-3 activation, apoptotic index and release of the necrosis marker lactate dehydrogenase to the extracellular medium were evaluated. ML9-induced cardiomyocyte death was not associated with increased intracellular ROS or decreased ATP levels. Moreover, treatment with ML9 significantly increased levels of the autophagy marker LC3-II, without altering Beclin1 or p62 protein levels. However, treatment with ML9 followed by bafilomycin-A1 did not produce further increases in LC3-II content. Furthermore, treatment with ML9 resulted in decreased LysoTracker (R) Green staining. Collectively, these data suggest that ML9-induced cardiomyocyte death is triggered by a ML9-dependent disruption of autophagic flux due to lysosomal dysfunction.FONDECYT, Chile 3150545 FONDAP 1513001

Gln(27)-> Glu beta(2)-Adrenergic Receptor Polymorphism in Heart Failure Patients: Differential Clinical and Oxidative Response to Carvedilol

We investigated the clinical response of chronic heart failure patients with beta(2)- adrenergic receptor Gln(27)-> Glu polymorphism treated for 6 months with carvedilol, a alpha/beta-antagonist with antioxidant properties. The 6-min. walk test, the left ventricular ejection fraction, heart rate, plasma norepinephrine and malondialdehyde, a stress oxidative marker, concentrations were evaluated at baseline and after treatment for 6 months with carvedilol in 33 stable chronic heart failure patients with the Gln(27)-> Glu beta(2)-adrenergic receptor polymorphism. Carvedilol significantly increased the left ventricular ejection fraction, while decreasing the heart rate and malondialdehyde plasma concentrations in chronic heart failure patients with the Glu(27)->beta(2)-adrenergic receptor allele. There were however, no significant changes in patients with the Gln(27)->beta(2)-adrenergic receptor variant