ABSTRACT
Mitochondria-endoplasmic reticulum (ER) communication relies on platforms formed at the ER membrane with the mitochondrial outer membrane contact sites (MERCs). MERCs are involved in several processes including the unfolded protein response (UPR) and calcium (Ca2+) signaling. Therefore, as alterations in MERCs greatly impact cellular metabolism, pharmacological interventions to preserve productive mitochondrial-ER communication have been explored to maintain cellular homeostasis. In this regard, extensive information has documented the beneficial and potential effects of sulforaphane (SFN) in different pathological conditions; however, controversy has arisen regarding the effect of this compound on mitochondria-ER interaction. Therefore, in this study, we investigated whether SFN could induce changes in MERCs under normal culture conditions without damaging stimuli. Our results indicate that non-cytotoxic concentration of 2.5 µM SFN increased ER stress in cardiomyocytes in conjunction with a reductive stress environment, that diminishes ER-mitochondria association. Additionally, reductive stress promotes Ca2+ accumulation in the ER of cardiomyocytes. These data show an unexpected effect of SFN on cardiomyocytes grown under standard culture conditions, promoted by the cellular redox unbalance. Therefore, it is necessary to rationalize the use of compounds with antioxidant properties to avoid triggering cellular side effects.
Subject(s)
Mitochondria , Myocytes, Cardiac , Myocytes, Cardiac/metabolism , Endoplasmic Reticulum , Unfolded Protein Response , Endoplasmic Reticulum StressABSTRACT
Extracellular vesicles are recognized as signaling mediators between cells both in physiological and pathological communication. In this work, we explored the potential effect of citicoline to modify relevant proteins or miRNAs for cardioprotection in the smallest population of such microvesicles; i.e., in exosomes from patients diagnosed with ST-segment elevation myocardial infarction (STEMI) undergoing coronary angioplasty. The plasma-exosome-enriched fraction from these patients was characterized. Their cellular origin was assessed by flow cytometry and Western blot, whereas miRNA expression was evaluated by real-time polymerase chain reaction (qRT-PCR). The content of caveolin-1, caveolin-3, and hnRNPA2B1, which play a relevant role in selective transport of miRNAs into microvesicles, along with the effect on cell viability of the exosomes obtained from citicoline-treated and untreated groups were also analyzed. Our results showed that hypoxic stress increases exosome release into the circulation. Moreover, we found that CD146+ increased in exosomes from citicoline-treated patients, while CD142+ decreased in these patients compared to the placebo group. No changes were detected in the protein levels of caveolin-1, caveolin-3, and hnRNPA2B1. Citicoline administration modified the expression of miR233-3p, miR92, and miR21-5p in exosomes. Cell viability decreased in the presence of exosomes from infarcted patients, while incubation of H9c2 cells with exosomes from patients reperfused with citicoline did not affect cell viability. In conclusion, citicoline administration modifies the expression of specific miRNAs related to cardioprotection in exosomes.
