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Circadian rhythm of enolase in suprachiasmatic nucleus depends on mitochondrial function
Author(s) -
Isobe Yoshiaki,
Hida Hideki,
Nishino Hitoo
Publication year - 2011
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.22610
Subject(s) - suprachiasmatic nucleus , per2 , circadian rhythm , enolase , biology , endocrinology , clock , medicine , chemistry , biochemistry , circadian clock , microbiology and biotechnology , immunohistochemistry , immunology
Metabolic activity in the suprachiasmatic nucleus (SCN), a center of biological rhythm, is higher during the daytime than at night. The rhythmic oscillation in the SCN is feedback controlled by the CLOCK/BMAL1 heterodimer binding to the E‐box in target genes (e.g., Arg‐ vasopressin). Similar transcriptional regulation by NPAS2/BMAL1 heterodimer formation operates in the brain, which depends on the redox state (i.e., NAD/NADH). To clarify the metabolic function of SCN in relation to the redox state, two‐dimensional electrophoresis was carried out on the mitochondrial fraction of SCN, obtained from rats kept under a light:dark cycle and constant under dim light. The electrophoretic pattern with TOF‐mass spectrometry analysis revealed that enolase catalyzes the interconversion of 2‐phosphoglycerate and phosphoenolpyruvate. The enolase activity, coupled with lactate dehydrogenase, was higher during the light period than that in the dark. However, enolase mRNA, analyzed by RT‐PCR, showed higher levels during the dark period than in the light. The clock gene products Per2, Bmal1, Rev‐erbα, and AVP mRNA in the mitochondrial fraction of SCN developed a circadian rhythm showing almost the same peak time as that in whole SCN. These mRNA rhythms ran free except for that of Rev‐erbα mRNA. The results indicate that, in the glycolysis‐related energy pathway, enolase might be involved in higher metabolic activity during the day than at night, at least in part. © 2011 Wiley‐Liss, Inc.