Figure 1.

PCBP1 is a period-short modifier for mammalian clocks. (A) Knockdown of PCBP1 results in a short period of circadian rhythm in U2OS cells harboring Per2-luc. Top right: Bars show quantitative period change values. (B) The knockdown efficiency of siPCBP1. The expression level of PCBP1 was knocked down to 6.6% compared to scramble. (C) Knockdown of PCBP1 using short hairpin RNA (shRNA) results in a short period of circadian rhythm in U2OS cells harboring Per2-luc, and the period had no obvious change in shPCBP2 cells. Top right: Bars show quantitative period change values. (D) The knockdown efficiency of shPCBP1 and shPCBP2 in U2OS cells harboring Per2-luc. The expression levels of PCBP1 and PCBP2 were 29.2 and 12.4% compared to scramble, respectively. (E) A transient transfection luciferase assay was conducted in 293 T cells to show that over-expressed PCBP1 decreased the transcriptional activity of CLOCK/BMAL1. (F) A transient transfection luciferase assay was conducted in shPCBP1 and shPCBP2 cells to show the difference in the transcription or repression activity. (G) The knockdown efficiency of shPCBP1 and shPCBP2 in 293 T cells. The bioluminescence traces in (A,C) were representative of five independent experiments, and the four additional experiments gave similar results. Mean and error bars (SEM) of five independent transfections are shown. Statistical significance was determined using Student’s t-tests (C), one-way ANOVA (A,B,D,G) or two-way ANOVA followed by Bonferroni’s multiple comparisons test (E,F). (n = 5, ^**p < 0.01, and ^***p < 0.001).