Selenoprotein-U (SelU) knockdown triggers autophagy through PI3K-Akt-mTOR pathway inhibition in rooster Sertoli cells.

Selenium (Se) is a major component of male reproduction which exerts its effects via selenoproteins. Selenoprotein U (SelU), a newly identified protein, is expressed highly in eukaryotes and possesses a conserved motif similar to that existing in other thiol-dependent redox regulating selenoproteins; however its function is unknown. To investigate the role of SelU in testis autophagic and/or apoptosis cell death mechanisms, we established a Sertoli cell (SC) model isolated from 45 day old layer roosters. Small interfering RNA (siRNA) technology was used to develop SelU-knockdown (SelU-KD) and normal (N) SC models. Consequent to transfection, electron microscopy, qPCR, and western blot were performed. The results show that the mRNA and proteins of autophagy and anti-apoptosis genes increased while that of anti-autophagic mammalian target of rapamycin (mTOR) and pro-apoptosis genes decreased significantly in SelU-KD in contrast to N cells. Simultaneously, in contrast to N cells the expression of phosphoinositide-3-kinase (PI3K) and protein kinase B (PKB/Akt) both at the mRNA and protein levels decreased significantly in SelU-KD cells. In-addition, SelU depletion altered the expression of regulatory factors and increased the mRNA of TSC (tuberous sclerosis complex) genes as compared to N cells. Extensive autophagosome formation and lysosome degradation with an intact cytoskeleton were observed in SelU-KD cells. Our data indicate that SelU deprivation elicits autophagy and reduces the expression of important growth factors in SCs by disrupting the PI3K-Akt-mTOR signaling pathway. However SelU attenuation did not induce apoptosis in rooster SCs. Taken together, we conclude that SelU is essential for the survival and normal functioning of SCs.

Selenium deficiency-induced alterations in ion profiles in chicken muscle.

Ion homeostasis plays important roles in development of metabolic diseases. In the present study, we examined the contents and distributions of 25 ions in chicken muscles following treatment with selenium (Se) deficiency for 25 days. The results revealed that in chicken muscles, the top ranked microelements were silicon (Si), iron (Fe), zinc (Zn), aluminum (Al), copper (Cu) and boron (B), showing low contents that varied from 292.89 ppb to 100.27 ppm. After Se deficiency treatment, essential microelements [Cu, chromium (Cr), vanadium (V) and manganese (Mn)], and toxic microelements [cadmium (Cd) and mercury (Hg)] became more concentrated (P < 0.05). Elements distribution images showed generalized accumulation of barium (Ba), cobalt (Co), Cu, Fe and V, while Cr, Mn, and Zn showed pin point accumulations in muscle sections. Thus, the ion profiles were generally influenced by Se deficiency, which suggested a possible role of Se deficiency in muscle dysfunctions caused by these altered ion profiles.

Analysis of the Interactions Between Thioredoxin and 20 Selenoproteins in Chicken.

Thioredoxin (Trx) is a small molecular protein with complicated functions in a number of processes, including inflammation, apoptosis, embryogenesis, cardiovascular disease, and redox regulation. Some selenoproteins, such as glutathione peroxidase (Gpx), iodothyronine deiodinase (Dio), and thioredoxin reductase (TR), are involved in redox regulation. However, whether there are interactions between Trx and selenoproteins is still not known. In the present paper, we used a Modeller, Hex 8.0.0, and the KFC2 Server to predict the interactions between Trx and selenoproteins. We used the Modeller to predict the target protein in objective format and assess the accuracy of the results. Molecular interaction studies with Trx and selenoproteins were performed using the molecular docking tools in Hex 8.0.0. Next, we used the KFC2 Server to further test the protein binding sites. In addition to the selenoprotein physiological functions, we also explored potential relationships between Trx and selenoproteins beyond all the results we got. The results demonstrate that Trx has the potential to interact with 19 selenoproteins, including iodothyronine deiodinase 1 (Dio1), iodothyronine deiodinase 3 (Dio3), glutathione peroxidase 1 (Gpx1), glutathione peroxidase 2 (Gpx2), glutathione peroxidase 3 (Gpx3), glutathione peroxidase 4 (Gpx4), selenoprotein H (SelH), selenoprotein I (SelI), selenoprotein M (SelM), selenoprotein N (SelN), selenoprotein T (SelT), selenoprotein U (SelU), selenoprotein W (SelW), selenoprotein 15 (Sep15), methionine sulfoxide reductase B (Sepx1), selenophosphate synthetase 1 (SPS1), TR1, TR2, and TR3, among which TR1, TR2, TR3, SPS1, Sep15, SelN, SelM, SelI, Gpx2, Gpx3, Gpx4, and Dio3 exhibited intense correlations with Trx. However, additional experiments are needed to verify them.

Selenoprotein W redox-regulated Ca2+ channels correlate with selenium deficiency-induced muscles Ca2+ leak.

Selenium (Se) deficiency induces Ca2+ leak and calcification in mammal skeletal muscles; however, the exact mechanism is still unclear. In the present study, both Se-deficient chicken muscle models and selenoprotein W (SelW) gene knockdown myoblast and embryo models were used to study the mechanism. The results showed that Se deficiency-induced typical muscular injuries accompanied with Ca2+ leak and oxidative stress (P < 0.05) injured the ultrastructure of the sarcoplasmic reticulum (SR) and mitochondria; decreased the levels of the Ca2+ channels, SERCA, SLC8A, CACNA1S, ORAI1, STIM1, TRPC1, and TRPC3 (P < 0.05); and increased the levels of Ca2+ channel PMCA (P < 0.05). Similarly, SelW knockdown also induced Ca2+ leak from the SR and cytoplasm; increased mitochondrial Ca2+ levels and oxidative stress; injured SR and mitochondrial ultrastructure; decreased levels of SLC8A, CACNA1S, ORA1, TRPC1, and TRPC3; and caused abnormal activities of Ca2+ channels in response to inhibitors in myoblasts and chicken embryos. Thus, both Se deficiency and SelW knockdown induced Ca2+ leak, oxidative stress, and Ca2+ channel reduction. In addition, Ca2+ levels and the expression of the Ca2+ channels, RyR1, SERCA, CACNA1S, TRPC1, and TRPC3 were recovered to normal levels by N-acetyl-L-cysteine (NAC) treatment compared with SelW knockdown cells. Thus, with regard to the decreased Ca2+ channels, SelW knockdown closely correlated Se deficiency with Ca2+ leak in muscles. The redox regulation role of SelW is crucial in Se deficiency-induced Ca2+ leak in muscles.

Incidence and prognostic implication of unrecognized myocardial scar characterized by cardiac magnetic resonance in diabetic patients without clinical evidence of myocardial infarction.

BACKGROUND: Silent myocardial infarctions (MIs) are prevalent among diabetic patients and inflict significant morbidity and mortality. Although late gadolinium enhancement (LGE) imaging by cardiac magnetic resonance (CMR) can provide sensitive characterization of myocardial scar, its prognostic significance in diabetic patients without any clinical evidence of MI is unknown. METHODS AND RESULTS: We performed clinically indicated CMR imaging in 187 diabetic patients who were grouped by the absence (study group, n=109) or presence (control group, n=78) of clinical evidence of MI (clinical history of MI or Q waves on ECG). CMR imaging and follow-up were successful in 107 study patients (98%) and 74 control patients (95%). Cox regression analyses were performed to associate LGE with major adverse cardiovascular events (MACE), including death, acute MI, new congestive heart failure or unstable angina, stroke, and significant ventricular arrhythmias. LGE by CMR was present in 30 of 107 study patients (28%). At a median follow-up of 17 months, 38 of 107 patients (36%) experienced MACE, which included 18 deaths. Presence of LGE was associated with a >3-fold hazards increase for MACE and for death (hazard ratio, 3.71 and 3.61; P<0.001 and P=0.007, respectively). Adjusted to a model that combines patient age, sex, ST or T changes on ECG, and left ventricular end-systolic volume index, LGE maintained a >4-fold hazards increase for MACE (adjusted hazard ratio, 4.13; 95% confidence interval, 1.74 to 9.79; P=0.001). In addition, LGE provided significant prognostic value with MACE and with death adjusted to a diabetic-specific risk model for 5-year events. The presence of LGE was the strongest multivariable predictor of MACE and death by stepwise selection in the study patients. CONCLUSIONS: CMR imaging can characterize occult myocardial scar consistent with MI in diabetic patients without clinical evidence of MI. This imaging finding demonstrates strong association with MACE and mortality hazards that is incremental to clinical, ECG, and left ventricular function combined.