C-FOS CRE-BINDING ACTIVITY OF CREB ATF FAMILY IN THE SCN IS REGULATEDBY LIGHT BUT NOT A CIRCADIAN CLOCK/

The DNA-binding activity of cAMP-responsive element binding protein (C REB) in the suprachiasmatic nucleus (SCN) was examined with Ca or cAMP -responsive element (Ca/CRE) in upstream sequence of c-fos gene using electro-mobility shift assay (EMSA). By using supershift assay, Ca/CRE -binding activity in the SCN was shown to contain not only CREB bur al so activating transcription factor-1 (ATF-1). Furthermore, photic-indu ction of CREB binding activity to Ca/CRE in the SCN occurred at all ci rcadian times tested, indicating that CREB DNA-binding in the SCN was not gated by the endogenous clock. These results implicated the role o f CREB/ATF family in photic neuronal signaling in the SCN.