Molecular characterization of NDRG4/Bdm1 protein isoforms that are differentially regulated during rat brain development.
We previously reported the identification of a novel gene, Bdm1/NDRG4, that was expressed predominantly in the postnatal rat brain and might possibly play a role in this process. We describe here the characterization of a NDRG4 protein in a developing and maturing rat brain. Antibody raised against glutathione S-transferase (GST)-NDRG4 fusion protein recognized four protein species of 38, 39, 41, and 45 kDa on Western blotting of proteins from differently staged rat brains. The 38-kDa form was revealed after birth, and the amount of this species peaked on postnatal day 15. The 39-kDa form became detectable after postnatal week 6. The 41-kDa form appeared late in embryogenesis, increased by postnatal day 15, and disappeared at postnatal week 6. The 45-kDa form was abundant during the late embryonic period and slightly decreased after birth. Subcellular fractionation of cerebra indicated that the NDRG4 protein was distributed mainly in the mitochondria and endoplasmic reticulum (ER). Detergent solubility assays and protease susceptibility demonstrated that in the ER NDRG4 protein is membrane-associated and luminally oriented. The 45-kDa isoform was induced during NGF-mediated neuronal differentiation of PC12 cells, but not by tunicamycin which causes ER stress. Differential expressions of NDRG4 protein isoforms may be a mechanism for modifying the NDRG4 function and for the formation of a functioning nervous system.
Nakada
Noriyuki
N
Department of Biochemistry, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
Hongo
Shigeki
S
Ohki
Takeshi
T
Maeda
Akihiko
A
Takeda
Minoru
M
D000375:Aging / Q000378:metabolism*; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001921:Brain / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009474:Neurons / Q000166:cytology; D016716:PC12 Cells; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
D018076:DNA, Complementary; D009124:Muscle Proteins; C486613:Ndrg4 protein, rat; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms