TY - JOUR
T1 - Selective restoration of the selenoprotein population in a mouse hepatocyte selenoproteinless background with different mutant selenocysteine tRNAs lacking Um34
AU - Carlson, Bradley A.
AU - Moustafa, Mohamed E.
AU - Sengupta, Aniruddha
AU - Schweizer, Ulrich
AU - Shrimali, Rajeev
AU - Rao, Mahadev
AU - Zhong, Nianxin
AU - Wang, Shulin
AU - Feigenbaum, Lionel
AU - Byeong, Jae Lee
AU - Gladyshev, Vadim N.
AU - Hatfield, Dolph L.
PY - 2007/11/9
Y1 - 2007/11/9
N2 - Novel mouse models were developed in which the hepatic selenoprotein population was targeted for removal by disrupting the selenocysteine (Sec) tRNA[Ser]Sec gene (trsp), and selenoprotein expression was then restored by introducing wild type or mutant trsp transgenes. The selenoprotein population was partially replaced in liver with mutant transgenes encoding mutations at either position 34 (34T→A) or 37 (37A→G) intRNA [Ser]Sec.The A34 transgene product lacked the highly modified 5-methoxycarbonylmethyl-2′-O-methyluridine, and its mutant base A was converted to I34. The G37 transgene product lacked the highly modified N 6-isopentenyladenosine. Both mutant tRNAs lacked the 2′-methylribose at position 34 (Um34), and both supported expression of housekeeping selenoproteins (e.g. thioredoxin reductase 1) in liver but not stress-related proteins (e.g. glutathione peroxidase 1). Thus, Um34 is responsible for synthesis of a select group of selenoproteins rather than the entire selenoprotein population. The ICA anticodon in the A34 mutant tRNA decoded Cys codons, UGU and UGC, as well as the Sec codon, UGA. However, metabolic labeling of A34 transgenic mice with 75Se revealed that selenoproteins incorporated the label from the A34 mutant tRNA, whereas other proteins did not. These results suggest that the A34 mutant tRNA did not randomly insert Sec in place of Cys, but specifically targeted selected selenoproteins. High copy numbers of A34 transgene, but not G37 transgene, were not tolerated in the absence of wild type trsp, further suggesting insertion of Sec in place of Cys in selenoproteins.
AB - Novel mouse models were developed in which the hepatic selenoprotein population was targeted for removal by disrupting the selenocysteine (Sec) tRNA[Ser]Sec gene (trsp), and selenoprotein expression was then restored by introducing wild type or mutant trsp transgenes. The selenoprotein population was partially replaced in liver with mutant transgenes encoding mutations at either position 34 (34T→A) or 37 (37A→G) intRNA [Ser]Sec.The A34 transgene product lacked the highly modified 5-methoxycarbonylmethyl-2′-O-methyluridine, and its mutant base A was converted to I34. The G37 transgene product lacked the highly modified N 6-isopentenyladenosine. Both mutant tRNAs lacked the 2′-methylribose at position 34 (Um34), and both supported expression of housekeeping selenoproteins (e.g. thioredoxin reductase 1) in liver but not stress-related proteins (e.g. glutathione peroxidase 1). Thus, Um34 is responsible for synthesis of a select group of selenoproteins rather than the entire selenoprotein population. The ICA anticodon in the A34 mutant tRNA decoded Cys codons, UGU and UGC, as well as the Sec codon, UGA. However, metabolic labeling of A34 transgenic mice with 75Se revealed that selenoproteins incorporated the label from the A34 mutant tRNA, whereas other proteins did not. These results suggest that the A34 mutant tRNA did not randomly insert Sec in place of Cys, but specifically targeted selected selenoproteins. High copy numbers of A34 transgene, but not G37 transgene, were not tolerated in the absence of wild type trsp, further suggesting insertion of Sec in place of Cys in selenoproteins.
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U2 - 10.1074/jbc.M707036200
DO - 10.1074/jbc.M707036200
M3 - Article
C2 - 17848557
AN - SCOPUS:36348979164
SN - 0021-9258
VL - 282
SP - 32591
EP - 32602
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 45
ER -