Adipocyte-specific transcription factor ARF6 is a heterodimeric complex of two nuclear hormone receptors, PPAR gamma and RXR alpha.
Previously, we identified a novel transcription factor, ARF6, as a key regulator of the tissue-specific adipocyte P2 (aP2) enhancer. In order to identify the proteins which comprise the adipocyte ARF6 complex, we have purified this DNA binding activity from a cultured adipocyte cell line. We have developed a system for growth and differentiation of HIB-1B brown adipocytes in suspension culture that facilitates the production of large quantities of adipocyte nuclear extract. ARF6 was purified from HIB-1B nuclear extract by a combination of conventional and sequence-specific DNA affinity chromotography. Chemical sequencing and mass spectral analysis of tryptic peptides derived from the purified polypeptides identifies the ARF6 complex as a heterodimer of the retinoid X receptor alpha (RXR alpha) and the murine peroxisome proliferator activated receptor gamma (PPAR gamma). Of the known PPAR gamma isoforms, PPAR gamma is the predominant form expressed in adipose tissue. These results suggest that PPAR gamma 2 serves a unique function among PPAR family members as an important regulator of adipocyte-specific gene expression.
Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.
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Tontonoz
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Graves
A I
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Budavari
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Erdjument-Bromage
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Lui
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Hu
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Tempst
B M
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Spiegelman
D017667:Adipocytes / Q000502:physiology*; D002001:Adipose Tissue, Brown / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry; D004742:Enhancer Elements, Genetic; D008099:Liver / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry*; D018168:Receptors, Retinoic Acid / Q000737:chemistry*; D047488:Retinoid X Receptors; D014157:Transcription Factors / Q000737:chemistry*
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors