Fig. 2.

Light-induced CREB phosphorylation and Per gene transcription in Per2^Luc;mOpn4 cells. (A) Immunoblot analysis shows light-induced rise in pCREB levels after light stimulation at CT22. (B and C) Chromatin immunoprecipitation with antiacetylated H3K9 (B) and anti-pSer-133 CREB antibody (C) indicate enrichment of immunoprecipitated Per2 promoter DNA sequences relative to the antibody control in response to light pulses at CT12, CT22, or CT3 for acetylated H3K9 and at CT22 for pCREB. (D–F) q-PCR analysis shows that light exposure at CT12 (D), CT22 (E), or CT3 (F) increased Per2 mRNA levels compared with dark-treated samples. Samples were collected before light pulse (prepulse, or PP) as well as at indicated times (x axis) after 10-min light stimulation. Values in B–F are mean ± SEM (B and C) or mean ± SD (D–F); n = 3; *, P < 0.01 compared with the prepulse; Student's t test.