Selenocysteine modulates resistance to environmental stress and confers anti-aging effects in C. elegans

OBJECTIVE: The free radical theory of aging suggests that cellular oxidative damage caused by free radicals is a leading cause of aging. In the present study, we examined the effects of a well-known anti-oxidant amino acid derivative, selenocysteine, in response to environmental stress and aging using Caenorhabditis elegans as a model system. METHOD: The response to oxidative stress induced by H2O2 or ultraviolet irradiation was compared between the untreated control and selenocysteine-treated groups. The effect of selenocysteine on lifespan and fertility was then determined. To examine the effect of selenocysteine on muscle aging, we monitored the change in motility with aging in both the untreated control and selenocysteine-treated groups. RESULTS: Dietary supplementation with selenocysteine significantly increased resistance to oxidative stress. Survival after ultraviolet irradiation was also increased by supplementation with selenocysteine. Treatment with selenocysteine confers a longevity phenotype without an accompanying reduction in fertility, which is frequently observed in lifespan-extending interventions as a trade-off in C. elegans. In addition, the age-related decline in motility was significantly delayed by supplementation of selenocysteine. CONCLUSION: These findings suggest that dietary supplementation of selenocysteine can modulate response to stressors and lead to lifespan extension, thus supporting the free radical theory of aging.

Presentación diferencial de ARN mensajeros e identificación del gen selenocisteína liasa en células de carcinoma hepatocelular con expresión transitoria de la proteína core del virus de la hepatitis C / Differential display of messenger RNA and identification of selenocysteine luase gene in hepatocellular carcinoma cells transiently expressing hepatitis C virus Core protein

Introducción. El virus de la hepatitis C se asocia a diversas hepatopatías como hepatitis aguda, hepatitis crónica, esteatosis, cirrosis y carcinoma hepatocelular. Numerosos estudios han explorado mecanismos virales implicados en el establecimiento de la infección persistente y en las propiedades oncogénicas e inmunomoduladoras de la proteína core del virus de la hepatitis C. Las investigaciones orientadas a evaluar los cambios en la expresión de genes celulares endógenos inducidos por la proteína core son importantes para identificar genes candidatos responsables de los mecanismos de patogenicidad del virus de la hepatitis C. Objetivos. Comparar perfiles de expresión e identificar genes celulares endógenos en la línea celular derivada de carcinoma hepatocelular humano, HepG2, con expresión transitoria de la proteína core del virus de la hepatitis C. Materiales y métodos. Se utilizó la técnica de presentación diferencial de ARN mensajero por RT-PCR en células HepG2 con y sin expresión transitoria de la proteína core del virus de la hepatitis C o de la proteína verde fluorescente, obtenidas previamente con el sistema de expresión del Semliki Forest Virus, mediante transducción de partículas recombinantes rSFV-Core o rSFV-GFP. Resultados. Se observaron diferencias en las intensidades de las bandas de ARNm expresadas en células HepG2 transducidas con rSFV-Core comparadas con células sin transducir y trasducidas con rSFV-GFP. Un ARNm de 258 pb expresado diferencialmente en células HepG2 transducidas con rSFV-Core fue clonado e identificado como selenocisteína liasa. Conclusión. Los resultados confirman que la expresión de la proteína core del virus de la hepatitis C se asocia con cambios en la expresión de ARN mensajeros específicos, incluido al gen selenocisteina liasa, el cual puede estar involucrado en la fisiopatología del carcinoma hepatocelular

Effects of selenium and B-27 supplements on viability and differentiation of neural stem cell in newborn rat / 中华预防医学杂志

<p><b>OBJECTIVE</b>To assess how trace element selenium and B27 supplements affect the neural stem cell (NSc) differentiation in vitro.</p><p><b>METHODS</b>The development and differentiation of NSc from the newborn rat were observed with primary culture and subculture during treating by sodium-selenite, and selenium-methyl-cysteine (SMC). The immunocytochemistry techniques were used to identify the NSc and mature protein expression with neuron marker beta-tubulin, astrocyte marker GFAP, and oligodendrocyte marker CNPase. The neurosphere morphology and neurite outgrowth were observed.</p><p><b>RESULTS</b>Adding the complete B-27 serum-free supplement, Selenium could promote the neurosphere viability, development and differentiation. Without selenium and B-27, neurosphere could not survive and differentiate. Without B-27 in the medium but there containing selenium, the neurosphere could promote the viability and development into neuron, astrocyte and oligodendrocyte, as compared with the no-containing B-27 and selenium groups, these differentiated cells might have more quantity, more branches and better morphological nerve net. The count of the neuron, astrocyte and oligodendrocyte was 11.2/Hp, 16.1/Hp and 9.3/Hp.</p><p><b>CONCLUSIONS</b>The selenium should be very important for neural stem cells' survival. Selenium could promote the neurosphere cells differentiation and development.</p>

The apoptosis-inducing activity of human selenoprotein P shorter isoform / 中华肿瘤杂志

<p><b>OBJECTIVE</b>Human selenoprotein P (HSelP) is unique protein that contains 10 selenocysteines encoded by 10 inframe UGA, which typically function as stop codon. The function of HSelP remains unclear, in part due to the inability to express it by gene recombinant technique. This study is to investigate expression and purification of recombinant HSelP in prokaryotic expression system, and its activity to induce apoptosis in vitro.</p><p><b>METHODS</b>The shorter HSelP isoform was cloned. After the selenocysteine (SeCys) at 40th position from N terminus of the HSelP shorter isoform was mutated into cysteine by PCR, it was expressed in E. coli. The expressed product was purified with DEAE column and identified by Western blot. Subsequently, its function on induction of mitochondrial apoptotic activity was studied.</p><p><b>RESULTS</b>The mutant HSelP shorter isoform expressed in prokaryotic system was purified by DEAE column to 90% homogeneity. The purified product, HSelP280m, induced the opening of mitochondrial permeability transition pore (PTP) and decreased the transmembrane potential in a dose-dependent manner. These events could be abolished by PTP specific inhibitors.</p><p><b>CONCLUSION</b>HSelP280m can induce the opening of mitochondrial PTP, which provides a basis for investigating the structure and function of recombinant HSelP.</p>