Abstract
The neural stem cells (NSCs) are known to possess a self-renewal and multipoietic activity and are expected to be useful for several neurodegenarative diseases. However, the molecular mechanisms underlying the NSCs proliferation are not fully understood. Recently, Per2 gene was shown to have an important role in cell cycle regulation in tumor cells (Fu et al., 2002). Therefore, we speculate that Per2 plays a role in the proliferation of the NSCs. To assess this, we examined the time course of Per2 gene expression and proliferative activity in murine cultured NSCs. The NSCs derived from the striatum of E15.5 mice were cultured by neurosphere method. The cells were stimulated by EGF (20 ng/ml), a well known mitogen for NSCs, and the relative amount of Per2 mRNA and protein were measured by RT-PCR and immunocytochemistry, respectively. Simultaneously, the proleferative activity of NSCs was examined by WST-8 assay and BrdU incorporation assay. After EGF stimulation, the levels of Per2 mRNA and protein were transiently increased and subsequently showed circadian expressions with a period of 24 hr for at least 3 cycles. Furthermore, the degree of proliferation also showed circadian rhythm with an anti-phase to Per2 expression rhythm. These results suggest that Per2 gene plays a role in NSCs proliferation. [Jpn J Physiol 54 Suppl:S225 (2004)]
