Differential adrenergic regulation of C/EBP alpha and C/EBP beta in brown adipose tissue.

We investigated the regulation of the expression of two members of the C/EBP family of transcriptional activators, C/EBP alpha and C/EBP beta, in brown adipose tissue in mice. Less than one hour of cold exposure led to dramatic changes in the expression of both genes. C/EBP alpha steady-state mRNA and protein levels were drastically and rapidly reduced whereas C/EBP beta mRNA and protein levels were induced severalfold. Also norepinephrine injection affected the expression of the transcription factors. Preconfluent cells in brown fat primary cultures responded to norepinephrine with a decrease in C/EBP alpha and an increase in C/EBP beta mRNA; in confluent cells the expression of both factors was increased. Thus, C/EBP alpha and C/EBP beta gene expression is under adrenergic control both in vivo and in vitro but the type of response is directed by the degree of differentiation of the cells.