Expression of ubiquitin-related enzymes in the suprachiasmatic nucleus with special reference to ubiquitin carboxy-terminal hydrolase UchL1

There is growing evidence that ubiquitin-proteasome system plays an important role for the generation of circadian rhythms in mice as in Drosophila. Here we examined the expression of ubiquitin-related enzymes (Ubce5, UbcM4, Ube2v, Ube2d2, UchL1, UchL3, Ubp41, UfdlL, beta-TrCP) in the suprachiasmatic nucleus (SCN). At mRNA level, the-expression of these enzymes were faint to moderate except ubiquitin carboxy-terminal hydrolase L1 (UchL1), a dominant deubiquitinating salvaging enzyme. Although strongly expressed in the SCN, UchL1 mRNA did not show the rhythm in the SCN in both light-dark and constant dark conditions.