TY - JOUR
T1 - Transcriptional control of circadian hormone synthesis via the CREM feedback loop
AU - Foulkes, Nicholas S.
AU - Borjigin, Jimo
AU - Snyder, Solomon H.
AU - Sassone-Corsi, Paolo
PY - 1996/11/26
Y1 - 1996/11/26
N2 - Transcription factor cAMP-responsive element modulator (CREM) plays a key physiological and developmental role within the hypothalamic-pituitary- gonadal axis. The use of an alternative, intronic promoter within the CREM gene is responsible for the production of a cAMP-inducible repressor, inducible cAMP early repressor (ICER). ICER negatively autoregulates the ICER promoter, thus generating a feedback loop. We have previously documented a striking, clock-driven circadian fluctuation of CREM expression in the pineal gland. Oscillating ICER levels tightly correlate with fluctuations in the synthesis of the pineal hormone melatonin, whose production is also driven by the endogenous clock. Melatonin in turn regulates the hypothalamic-pituitary axis. The enzyme serotonin N- acetyltransferase (NOT) catalyzes the rate limiting step in melatonin synthesis. Thus, oscillations in NOT levels determine the circadian synthesis of melatonin. Here we demonstrate that NOT expression is dramatically increased in CREM-deficient mice that we have generated by homologous recombination. Characterization of the NOT promoter shows the presence of a ICER binding site. In addition, transfection studies show that ICER powerfully represses NOT transcription. Our results implicate CREM as a central regulator of output functions of the clock. Indeed, CREM acts as a key regulator of oscillatory hormonal synthesis.
AB - Transcription factor cAMP-responsive element modulator (CREM) plays a key physiological and developmental role within the hypothalamic-pituitary- gonadal axis. The use of an alternative, intronic promoter within the CREM gene is responsible for the production of a cAMP-inducible repressor, inducible cAMP early repressor (ICER). ICER negatively autoregulates the ICER promoter, thus generating a feedback loop. We have previously documented a striking, clock-driven circadian fluctuation of CREM expression in the pineal gland. Oscillating ICER levels tightly correlate with fluctuations in the synthesis of the pineal hormone melatonin, whose production is also driven by the endogenous clock. Melatonin in turn regulates the hypothalamic-pituitary axis. The enzyme serotonin N- acetyltransferase (NOT) catalyzes the rate limiting step in melatonin synthesis. Thus, oscillations in NOT levels determine the circadian synthesis of melatonin. Here we demonstrate that NOT expression is dramatically increased in CREM-deficient mice that we have generated by homologous recombination. Characterization of the NOT promoter shows the presence of a ICER binding site. In addition, transfection studies show that ICER powerfully represses NOT transcription. Our results implicate CREM as a central regulator of output functions of the clock. Indeed, CREM acts as a key regulator of oscillatory hormonal synthesis.
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U2 - 10.1073/pnas.93.24.14140
DO - 10.1073/pnas.93.24.14140
M3 - Article
C2 - 8943074
AN - SCOPUS:0030472180
SN - 0027-8424
VL - 93
SP - 14140
EP - 14145
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 24
ER -