Stimulation of ubiquitin-proteasome pathway through the expression of amidohydrolase for N-terminal asparagine (Ntan1) in cultured rat hippocampal neurons exposed to static magnetism.
In order to elucidate mechanisms underlying modulation by static magnetism of the cellular functionality and/or integrity in the brain, we screened genes responsive to brief magnetism in cultured rat hippocampal neurons using differential display analysis. We have for the first time cloned and identified Ntan1 (amidohydrolase for N-terminal asparagine) as a magnetism responsive gene in rat brain. Ntan1 is an essential component of a protein degradation signal, which is a destabilizing N-terminal residue of a protein, in the N-end rule. In situ hybridization histochemistry revealed abundant expression of Ntan1 mRNA in hippocampal neurons in vivo. Northern blot analysis showed that Ntan1 mRNA was increased about three-fold after 3 h in response to brief magnetism. Brief magnetism also increased the transcriptional activity of Ntan1 promoter by luciferase reporter assay. Brief magnetism induced degradation of microtubule-associated protein 2 (MAP2) without affecting cell morphology and viability, which was prevented by a selective inhibitor of 26S proteasome in hippocampal neurons. Overexpression of Ntan1 using recombinant Ntan1 adenovirus vector resulted in a marked decrease in the MAP2 protein expression in hippocampal neurons. Our results suggest that brief magnetism leads to the induction of Ntan1 responsible for MAP2 protein degradation through ubiquitin-proteasome pathway in rat hippocampal neurons.
Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Ishikawa, Japan.
Takao
T
Hirai
Hideo
H
Taniura
Yasuaki
Y
Goto
Masato
M
Ogura
Judy C G
JC
Sng
Yukio
Y
Yoneda
D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002470:Cell Survival / Q000502:physiology / Q000528:radiation effects; D002478:Cells, Cultured; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005822:Genetic Vectors / Q000502:physiology; D006624:Hippocampus / Q000201:enzymology / Q000528:radiation effects; D008279:Magnetic Resonance Imaging / Q000009:adverse effects; D008869:Microtubule-Associated Proteins / Q000378:metabolism* / Q000528:radiation effects; D008969:Molecular Sequence Data; D009474:Neurons / Q000201:enzymology / Q000528:radiation effects*; D011401:Promoter Regions, Genetic / Q000502:physiology / Q000528:radiation effects; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism / Q000528:radiation effects*; D012333:RNA, Messenger / Q000378:metabolism / Q000528:radiation effects; D051381:Rats; D015533:Transcriptional Activation / Q000502:physiology / Q000528:radiation effects; D025801:Ubiquitin / Q000378:metabolism / Q000528:radiation effects*; D015854:Up-Regulation / Q000502:physiology / Q000528:radiation effects
D004791:Enzyme Inhibitors; D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; D000581:Amidohydrolases; C425491:N-terminal asparagine amidohydrolase