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Selenocysteine tRNA[Ser]Sec levels and selenium-dependent glutathione peroxidase activity in mouse embryonic stem cells heterozygous for a targeted mutation in the tRNA[Ser]Sec gene.
Biochemistry. 1997 Jul 15; 36(28):8634-9.B

Abstract

To investigate the effect of a reduced level of selenocysteine (Sec) tRNA[Ser]Sec in selenoprotein biosynthesis, two mouse embryonic stem (ES) cell lines heterozygous for the corresponding gene were generated by homologous recombination of the host genome with targeting vectors encoding a deleted or a disrupted tRNA[Ser]Sec gene. The presence of a single functional gene in ES cells afforded us an opportunity to determine directly in the cell line the effect of reduced gene dosage on (1) the levels of the Sec tRNA[Ser]Sec population, (2) the distributions of the isoacceptors within the Sec tRNA population, and (3) selenoprotein biosynthesis. We therefore determined the amounts and distributions of the two major tRNA[Ser]Sec isoacceptors, designated mcm5U and mcm5Um, within the Sec tRNA population and determined the activity of the anti-oxidant, selenium-containing glutathione peroxidase (GPx) in the heterozygotes and in wild type cells grown in media with and without added selenium. The level of the Sec tRNA[Ser]Sec population in the heterozygotes was approximately 60% of that of wild type cells grown in media under normal conditions, while the ratio of the mcmU isoacceptor in wild type vs mutant cells was approximately 2:1 and of the mcmUm isoacceptor approximately 1:1. In the presence of media supplemented with selenium, the Sec tRNA[Ser]Sec population increased about 20% in wild type cells and virtually not all in heterozygous cells, and the level of the Sec tRNA[Ser]Sec population was, therefore, approximately 50% of that of wild type cells. GPx activity was indistinguishable among these cell lines in either selenium-supplemented or unsupplemented media, indicating that the resultant changes in tRNA[Ser]Sec levels did not have a measurable effect on GPx biosynthesis.

Authors+Show Affiliations

Section on the Molecular Biology of Selenium, Laboratory of Basic Research, Laboratory of Metabolism, Experimental Immunology Branch, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

9214310

Citation

Chittum, H S., et al. "Selenocysteine tRNA[Ser]Sec Levels and Selenium-dependent Glutathione Peroxidase Activity in Mouse Embryonic Stem Cells Heterozygous for a Targeted Mutation in the tRNA[Ser]Sec Gene." Biochemistry, vol. 36, no. 28, 1997, pp. 8634-9.
Chittum HS, Baek HJ, Diamond AM, et al. Selenocysteine tRNA[Ser]Sec levels and selenium-dependent glutathione peroxidase activity in mouse embryonic stem cells heterozygous for a targeted mutation in the tRNA[Ser]Sec gene. Biochemistry. 1997;36(28):8634-9.
Chittum, H. S., Baek, H. J., Diamond, A. M., Fernandez-Salguero, P., Gonzalez, F., Ohama, T., Hatfield, D. L., Kuehn, M., & Lee, B. J. (1997). Selenocysteine tRNA[Ser]Sec levels and selenium-dependent glutathione peroxidase activity in mouse embryonic stem cells heterozygous for a targeted mutation in the tRNA[Ser]Sec gene. Biochemistry, 36(28), 8634-9.
Chittum HS, et al. Selenocysteine tRNA[Ser]Sec Levels and Selenium-dependent Glutathione Peroxidase Activity in Mouse Embryonic Stem Cells Heterozygous for a Targeted Mutation in the tRNA[Ser]Sec Gene. Biochemistry. 1997 Jul 15;36(28):8634-9. PubMed PMID: 9214310.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Selenocysteine tRNA[Ser]Sec levels and selenium-dependent glutathione peroxidase activity in mouse embryonic stem cells heterozygous for a targeted mutation in the tRNA[Ser]Sec gene. AU - Chittum,H S, AU - Baek,H J, AU - Diamond,A M, AU - Fernandez-Salguero,P, AU - Gonzalez,F, AU - Ohama,T, AU - Hatfield,D L, AU - Kuehn,M, AU - Lee,B J, PY - 1997/7/15/pubmed PY - 1997/7/15/medline PY - 1997/7/15/entrez SP - 8634 EP - 9 JF - Biochemistry JO - Biochemistry VL - 36 IS - 28 N2 - To investigate the effect of a reduced level of selenocysteine (Sec) tRNA[Ser]Sec in selenoprotein biosynthesis, two mouse embryonic stem (ES) cell lines heterozygous for the corresponding gene were generated by homologous recombination of the host genome with targeting vectors encoding a deleted or a disrupted tRNA[Ser]Sec gene. The presence of a single functional gene in ES cells afforded us an opportunity to determine directly in the cell line the effect of reduced gene dosage on (1) the levels of the Sec tRNA[Ser]Sec population, (2) the distributions of the isoacceptors within the Sec tRNA population, and (3) selenoprotein biosynthesis. We therefore determined the amounts and distributions of the two major tRNA[Ser]Sec isoacceptors, designated mcm5U and mcm5Um, within the Sec tRNA population and determined the activity of the anti-oxidant, selenium-containing glutathione peroxidase (GPx) in the heterozygotes and in wild type cells grown in media with and without added selenium. The level of the Sec tRNA[Ser]Sec population in the heterozygotes was approximately 60% of that of wild type cells grown in media under normal conditions, while the ratio of the mcmU isoacceptor in wild type vs mutant cells was approximately 2:1 and of the mcmUm isoacceptor approximately 1:1. In the presence of media supplemented with selenium, the Sec tRNA[Ser]Sec population increased about 20% in wild type cells and virtually not all in heterozygous cells, and the level of the Sec tRNA[Ser]Sec population was, therefore, approximately 50% of that of wild type cells. GPx activity was indistinguishable among these cell lines in either selenium-supplemented or unsupplemented media, indicating that the resultant changes in tRNA[Ser]Sec levels did not have a measurable effect on GPx biosynthesis. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/9214310/Selenocysteine_tRNA[Ser]Sec_levels_and_selenium_dependent_glutathione_peroxidase_activity_in_mouse_embryonic_stem_cells_heterozygous_for_a_targeted_mutation_in_the_tRNA[Ser]Sec_gene_ L2 - https://dx.doi.org/10.1021/bi970608t DB - PRIME DP - Unbound Medicine ER -