Regulated expression of three C/EBP isoforms during adipose conversion of 3T3-L1 cells

Genes Dev. 1991 Sep;5(9):1538-52. doi: 10.1101/gad.5.9.1538.


In an effort to identify protein factors that play a regulatory role in the differentiation of adipocytes, we have isolated two genes that encode polypeptides related to CCAAT/enhancer-binding protein (C/EBP; hereafter termed C/EBP alpha). The proteins encoded by these C/EBP-related genes, termed C/EBP beta and C/EBP delta, exhibit similar DNA-binding specificities and affinities compared with C/EBP alpha. Furthermore, C/EBP beta and C/EBP delta readily form heterodimers with one another as well as with C/EBP alpha. The transcriptional activating capacity of these two newly identified C/EBP isoforms was demonstrated by transient transfection experiments in which expression vectors encoding C/EBP beta and C/EBP delta were observed to induce transcription from the promoter of the serum albumin gene in cultured hepatoma cells. The mRNAs encoding C/EBP beta and C/EBP delta were detected in a number of tissues, most of which corresponded to sites of expression of C/EBP alpha. The expression pattern of C/EBP beta and C/EBP delta during adipose conversion of 3T3-L1 cells was examined by Western and Northern blotting assays. In contrast to the expression profile of the gene encoding C/EBP alpha, whose product is not detectable until the late phase of adipocyte differentiation, the c/ebp beta and c/ebp delta genes were actively expressed very early during adipocyte differentiation. Moreover, transcription of the c/ebp beta and c/ebp delta genes was observed to be induced directly by adipogenic hormones. The accumulation of C/EBP beta and C/EBP delta reached a maximal level during the first 2 days of differentiation and declined sharply before the onset of C/EBP alpha accumulation. The temporal pattern of expression of these three C/EBP isoforms during adipocyte differentiation may reflect the underpinnings of a regulatory cascade that controls the process of terminal cell differentiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / cytology*
  • Adipose Tissue / metabolism
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Blotting, Northern
  • Blotting, Western
  • CCAAT-Enhancer-Binding Proteins
  • Cell Differentiation
  • Cell Line
  • Cloning, Molecular
  • DNA / metabolism
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / isolation & purification
  • Gene Expression Regulation*
  • Leucine Zippers
  • Mice
  • Molecular Sequence Data
  • Nuclear Proteins / biosynthesis
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / isolation & purification
  • Sequence Alignment
  • Transcriptional Activation


  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Nuclear Proteins
  • DNA

Associated data

  • GENBANK/M31698
  • GENBANK/M31699
  • GENBANK/M58400
  • GENBANK/M58401
  • GENBANK/M58402
  • GENBANK/X60094
  • GENBANK/X60401
  • GENBANK/X60402
  • GENBANK/X60403
  • GENBANK/X61800