Using immortalized cell lines to study daily rhythm control in main and peripheral body clocks in real time

Self-sustained circadian oscillations in SCN cells persisted for at least four cycles with periodicities of ≈24 h.

• Immortalized SCN cells exhibited coordinated circadian rhythms in luminescence driven by the mPER2::LUC fusion protein.
• Fibroblasts showed rhythmic expression of mPER2::LUC only in response to serum shock or when co-cultured with SCN2.2 cells.
• Circadian luminescence in fibroblasts decayed after 3-4 cycles in serum-shocked cultures but persisted for 6-7 cycles in co-culture with SCN2.2 cells.
• The rhythmicity of fibroblasts in co-culture was dependent on the functional integrity of the molecular clock in SCN cells.
• Immortalized SCN and fibroblast cells maintain their unique circadian properties, suggesting potential for studying clock gene rhythms.

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