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Cell Type-Specific Functions of Period Genes Revealed by Novel Adipocyte and Hepatocyte Circadian Clock Models

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shRNA-mediated knockdowns of Per1, Per2 and Per3 lead to cell type-specific circadian phenotypes.

Bioluminescence expression patterns upon KD of Per1 (A), Per2 (B), and Per3 (C) in all three cell types. See Figure 2 for details. Whereas Per3 KD led to short periods in all three cell types, Per1 and Per2 KDs caused different clock phenotypes depending on cell type. (D) Summary of period length phenotypes. Data are mean ± SD (n = 4 independent experiments for 3T3 cells; n = 3 samples/wells of one experiment for 3T3-L1 and MMH-D3 cells). NS, non-specific shRNA. Compared to NS controls, significant difference in period length was detected in the following KDs: NS vs. Per1 KD in MMH-D3, t-test, p<0.001; NS vs. Per2 KD in 3T3, t-test, p = 0.013; NS vs. Per2 KD in MMH-D3, t-test, p<0.001; NS vs. Per3 KD in 3T3, t-test, p<0.001; NS vs. Per3 KD in 3T3-L1, t-test, p = 0.003; NS vs. Per3 KD in MMH-D3, t-test, p<0.001). *p<0.01; ** p<0.001. (E) Per3 deletion led to short period length defects in SCN explants (left) and even stronger defects in dissociated SCN neurons (right). Per3−/− SCN explants show a slightly shorter period than WT (mean ± SEM: WT, 24.4 hr±0.17, n = 5; Per3−/−, 23.78 hr±0.18, n = 5). The mean period of rhythms in Per3−/− neurons was substantially shorter than in WT cells (mean ± SEM: WT, 27.23 hr±0.24, n = 106; Per3−/−, 25.58 hr±0.12, n = 157; t-test, p<10E-10; ** p<0.001).

Figure 4