A novel alternative spliced Mpv17-like protein isoform localizes in cytosol and is expressed in a kidney- and adult-specific manner.
Mpv17-like protein (M-LP) has been identified as a new protein that shows high sequence homology with Mpv17 protein, a peroxisomal membrane protein involved in the development of early onset glomerulosclerosis. We previously showed that the originally identified M-LP isoform, designated M-LPL, is, like Mpv17, localized in peroxisomes, and that transfection with M-LPL up-regulates expression of the manganese superoxide dismutase (SOD2) gene [R. Iida, T. Yasuda, E. Tsubota, H. Takatsuka, M. Masuyama, T. Matsuki, K. Kishi, M-LP, Mpv17-like protein, has a peroxisomal membrane targeting signal comprising a transmembrane domain and a positively charged loop and up-regulates expression of the manganese superoxide dismutase gene. J. Biol. Chem. 278 (2003) 6301-6306.]. We report here the identification of a novel alternative splicing product of the M-LP gene, designated M-LPS. A comparison of the genomic sequence with the cDNA sequences and an analysis of 5'-flanking regions revealed that the two isoforms are generated by alternative usage of two promoters. M-LPS consists of the C-terminal half of M-LPL (90 amino acids) and therefore lacks the peroxisome targeting signal of membrane protein that exists near the N-terminus of M-LPL. Expression of green fluorescent protein-tagged M-LPS in COS-7 cells demonstrated that M-LPS localizes in the cytosol. In mice, M-LPS is expressed exclusively in kidneys after the age of 6 weeks. Moreover, quantitative real-time PCR analysis revealed that transfection with M-LPS up-regulates expression of the SOD2 gene and down-regulates expression of the cellular glutathione peroxidase (Gpx1) and plasma glutathione peroxidase (Gpx3) genes. Taken together, these results suggest different functional attributes of the two M-LP isoforms during aging and development.
Iida
Reiko
R
Department of Forensic Medicine, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan. ireiko@fmsrsa.fukui-med.ac.jp
Yasuda
Toshihiro
T
Tsubota
Etsuko
E
Takatsuka
Hisakazu
H
Masuyama
Mika
M
Matsuki
Takasumi
T
Kishi
Koichiro
K
D000367:Age Factors; D000375:Aging / Q000235:genetics / Q000378:metabolism; D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001483:Base Sequence / Q000235:genetics; D019556:COS Cells; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D020675:Peroxisomes / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics; D000094765:Glutathione Peroxidase GPX1; D000099156:Superoxide Dismutase 2
D018076:DNA, Complementary; D005979:Glutathione Peroxidase; D008565:Membrane Proteins; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000094765:Glutathione Peroxidase GPX1; D000099156:Superoxide Dismutase 2; C427206:Mpv17l protein, mouse; C116888:Gpx3 protein, mouse; C000722068:Gpx1 protein, mouse