RESUMEN
The effects of Cu(2+) on the activity and expression of laccase were investigated in seven different strains of Pycnoporus coccineus collected from different regions in Korea. Cu(2+) was toxic to mycelial growth at concentrations greater than 0.5 mM CuSO4 and showed complete growth inhibition at 1 mM in the liquid culture. However, Cu(2+) significantly upregulated the extracellular laccase activity at 0.2 mM in five strains of P. coccineus, IUM4209, IUM0032, IUM0450, IUM0470, and IUM4093, whereas two strains, IUM0253 and IUM0049, did not respond to Cu(2+), despite being closely related to the other five strains. Subsequent RT-PCR analysis also showed that the laccase mRNA was highly expressed only in the former five strains in the presence of Cu(2+). Taken together, these results indicate that Cu(2+) regulates expression of the laccase gene in a strain-dependent manner. The five strains commonly produced a single predominant laccase protein with a molecular weight of 68 kDa. Peptide sequencing revealed that the laccase was a homolog of Lcc1 of P. coccineus, which was isolated in China. The Cu(2+)-induced culture supernatants exhibited high degradation of polycyclic aromatic hydrocarbons, indicating that the 68-kDa laccase is the primary extracellular degradative enzyme in P. coccineus.
Asunto(s)
Sulfato de Cobre/farmacología , Regulación Fúngica de la Expresión Génica/efectos de los fármacos , Lacasa/metabolismo , Pycnoporus/metabolismo , Secuencia de Aminoácidos , China , Lacasa/genética , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Hidrocarburos Policíclicos Aromáticos/metabolismo , Pycnoporus/clasificación , Pycnoporus/genética , República de Corea , Alineación de SecuenciaRESUMEN
DRG2, a member of the DRG subfamily in the GTP-binding protein superfamily, was identified as a repressed gene product in fibroblasts transformed by SV40. The significance of this down-regulation and the cellular role of DRG2 has not been understood in the past. To investigate the function of DRG2 we made a Jurkat cell line, Jurkat-LNCX2-DRG2, stably transfected with pLNCX2-DRG2 to overexpress human DRG2. Cell cycle distribution analysis revealed an increased accumulation of G(2)/M phase cells in Jurkat-LNCX2-DRG2 cells, indicating a retardation of cell-cycle progression. In addition, an overexpression of DRG2 reduced the sensitivity of Jurkat cells to the mitotic poison nocodazole. Our data suggest that overexpression of DRG2 in Jurkat cells affects genes regulating cell-cycle arrest and apoptosis, and that these molecular changes may be important in the growth or differentiation of cells.
Asunto(s)
Apoptosis/efectos de los fármacos , División Celular , Fase G2 , Proteínas de Unión al GTP/genética , Proteínas de Unión al GTP/metabolismo , Nocodazol/farmacología , División Celular/efectos de los fármacos , Fase G2/efectos de los fármacos , Humanos , Células Jurkat , ARN Mensajero/genética , ARN Mensajero/metabolismo , TransfecciónRESUMEN
Developmentally regulated GTP-binding protein (DRG) is a new subfamily within the superfamily of GTP-binding proteins. Its expression is regulated during embryonic development. To investigate the effect of the expression of DRG2 on cell growth, we constructed a human Jurkat-T-cell line that overexpresses DRG2. Overexpression of DRG2 suppressed the growth and the aggregation of Jurkat cells but did not induce apoptotic cell death. We used cDNA microarray analysis to examine the global changes in gene expression induced by an overexpression of DRG2. DNA array analyses identified genes that may suppress cell growth at a number of levels in multiple signaling cascades in Jurkat cells and also several prosurvival genes that may protect cells from apoptosis.