The Antioxidant Selenoprotein T Mimetic, PSELT, Induces Preconditioning-like Myocardial Protection by Relieving Endoplasmic-Reticulum Stress

Abstract

Oxidative stress and endoplasmic reticulum stress (ERS) are strictly involved in myocardial ischemia/reperfusion (MI/R). Selenoprotein T (SELENOT), a vital thioredoxin-like selenoprotein, is crucial for ER homeostasis and cardiomyocyte differentiation and protection, likely acting as a redox-sensing protein during MI/R. Here, we designed a small peptide (PSELT), encompassing the redox site of SELENOT, and investigated whether its pre-conditioning cardioprotective effect resulted from modulating ERS during I/R. The Langendorff rat heart model was employed for hemodynamic analysis, while mechanistic studies were performed in perfused hearts and H9c2 cardiomyoblasts. PSELT improved the post-ischemic contractile recovery, reducing infarct size and LDH release with and without the ERS inducer tunicamycin (TM). Mechanistically, I/R and TM upregulated SELENOT expression, which was further enhanced by PSELT. PSELT also prevented the expression of the ERS markers CHOP and ATF6, reduced cardiac lipid peroxidation and protein oxidation, and increased SOD and catalase activities. An inert PSELT (I-PSELT) lacking selenocysteine was ineffective. In H9c2 cells, H2O2 decreased cell viability and SELENOT expression, while PSELT rescued protein levels protecting against cell death. In SELENOT-deficient H9c2 cells, H2O2 exacerbated cell death, that was partially mitigated by PSELT. Microscopy analysis revealed that a fluorescent form of PSELT was internalized into cardiomyocytes with a perinuclear distribution. Conclusions: The cell-permeable PSELT is able to induce pharmacological preconditioning cardioprotection by mitigating ERS and oxidative stress, and by regulating endogenous SELENOT.

Palmitate-Induced Cardiac Lipotoxicity Is Relieved by the Redox-Active Motif of SELENOT through Improving Mitochondrial Function and Regulating Metabolic State

“…SELENOT is strongly expressed in human and mouse pancreatic β- and δ-cells, and conditional pancreatic β-cell SELENOT-knockout mice exhibited impaired glucose tolerance with a deficit in insulin production/secretion [ 14 ]. On the other hand, SELENOT is highly expressed during the early hyperplastic growth of cardiomyocytes, suggesting its involvement in cardiac development during embryogenesis, and can also protect cardiomyocytes following myocardial ischemia/reperfusion (MI/R) insult [ 15 , 16 ].…”

Emerging roles of ER-resident selenoproteins in brain physiology and physiopathology

“…Several recent ones have recently reported the use of selenoprotein-derived peptides with promising results in brain disorders. The selenopeptide, PSELT, composed of 10 amino acids with a Sec redox center, is protective in a rat model of peripheral nerve neurodegeneration and a MPTP mouse model of PD, but also in a rat model of cardiac ischemia-reperfusion [ 93 , [178] , [179] , [180] ]. Transcriptomic analysis revealed that gene regulation by PSELT after MPP + treatment of neuroblastoma cells is positively correlated with that after resveratrol treatment.…”

Quercetin and Its Derivative Counteract Palmitate-Dependent Lipotoxicity by Inhibiting Oxidative Stress and Inflammation in Cardiomyocytes

“…H9c2 cardiomyocytes were purchased from the American Type Culture Collection (ATCC) (Manassas, VA, USA) (Cat# CRL -1446) and cultured as described in our previous publications [ 27 , 28 , 29 , 30 ]. When cell confluence reached 80%, H9c2 cardiomyocytes were digested in a 1:2 ratio with 0.25% trypsin-EDTA (1X) (Gibco), according to the manufacturer’s instructions (ATCC).…”

“…When cell confluence reached 80%, H9c2 cardiomyocytes were digested in a 1:2 ratio with 0.25% trypsin-EDTA (1X) (Gibco), according to the manufacturer’s instructions (ATCC). For all experiments, H9c2 cells were plated in complete medium and incubated at 37 °C and 5% CO 2 for 48 h, as previously reported [ 27 , 28 , 29 , 30 ].…”

“…The viability of the H9c2 cells was determined by the 3-(4,5-dimethylthiazol-)2,5-diphenyl tetrazonium bromide (MTT) assay as previously described [ 27 , 29 , 30 ]. In brief, H9c2 cardiomyocytes (5 × 10 3 cells/well) were seeded in 96-well plates and then treated with palmitate (PA) (from 100 to 500 µM) or vehicle (BSA), indicated as a control, for 24 h. To prepare a 10 mM stock solution, PA (Sigma Aldrich) was solubilized with 10% BSA fatty-acid-free at a molar ratio of 6:1 (PA: BSA) [ 8 ].…”