title: MsrB1 (methionine-R-sulfoxide reductase 1) knock-out mice: roles of MsrB1 in redox regulation and identification of a novel selenoprotein form.
abstract: Protein oxidation has been linked to accelerated aging and is a contributing factor to many diseases. Methionine residues are particularly susceptible to oxidation, but the resulting mixture of methionine R-sulfoxide (Met-RO) and methionine S-sulfoxide (Met-SO) can be repaired by thioredoxin-dependent enzymes MsrB and MsrA, respectively. Here, we describe a knock-out mouse deficient in selenoprotein MsrB1, the main mammalian MsrB located in the cytosol and nucleus. In these mice, in addition to the deletion of 14-kDa MsrB1, a 5-kDa selenoprotein form was specifically removed. Further studies revealed that the 5-kDa protein occurred in both mouse tissues and human HEK 293 cells; was down-regulated by MsrB1 small interfering RNA, selenium deficiency, and selenocysteine tRNA mutations; and was immunoprecipitated and recognized by MsrB1 antibodies. Specific labeling with (75)Se and mass spectrometry analyses revealed that the 5-kDa selenoprotein corresponded to the C-terminal sequence of MsrB1. The MsrB1 knock-out mice lacked both 5- and 14-kDa MsrB1 forms and showed reduced MsrB activity, with the strongest effect seen in liver and kidney. In addition, MsrA activity was decreased by MsrB1 deficiency. Liver and kidney of the MsrB1 knock-out mice also showed increased levels of malondialdehyde, protein carbonyls, protein methionine sulfoxide, and oxidized glutathione as well as reduced levels of free and protein thiols, whereas these parameters were little changed in other organs examined. Overall, this study established an important contribution of MsrB1 to the redox control in mouse liver and kidney and identified a novel form of this protein.
authors.affiliation: Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska 68588, USA.
authors.forename: Dmitri E
authors.initials: DE
authors.lastname: Fomenko
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Novoselov
authors.forename: Sathish Kumar
authors.initials: SK
authors.lastname: Natarajan
authors.forename: Byung Cheon
authors.initials: BC
authors.lastname: Lee
authors.forename: Ahmet
authors.initials: A
authors.lastname: Koc
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Carlson
authors.forename: Tae-Hyung
authors.initials: TH
authors.lastname: Lee
authors.forename: Hwa-Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Dolph L
authors.initials: DL
authors.lastname: Hatfield
authors.forename: Vadim N
authors.initials: VN
authors.lastname: Gladyshev
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019587:Dietary Supplements; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008315:Malondialdehyde / Q000378:metabolism; D051150:Methionine Sulfoxide Reductases / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000502:physiology*; D050050:Protein Carbonylation; D011487:Protein Conformation; D012643:Selenium / Q000378:metabolism*; D051140:Selenoproteins / Q000502:physiology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D008840:Microfilament Proteins; D051140:Selenoproteins; D008315:Malondialdehyde; D010088:Oxidoreductases; D051150:Methionine Sulfoxide Reductases; C000614737:MsrB1 protein, mouse; C520510:Msrb2 protein, mouse; C027219:methionine sulfoxide reductase; D005978:Glutathione; D012643:Selenium