SREBP-1 dimerization specificity maps to both the helix-loop-helix and leucine zipper domains: Use of a dominant negative

Vikas Rishi, Jozsef Gal, Dmitry Krylov, Jakob Fridriksson, Maria Sandberg Boysen, Susanne Mandrup, Charles Vinson

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

The mammalian SREBP family contains two genes that code for B-HLH-ZIP proteins that bind sequence-specific DNA to regulate the expression of genes involved in lipid metabolism. We have designed a dominant negative (DN), termed A-SREBP-1, that inhibits the DNA binding of either SREBP protein. A-SREBP-1 consists of the dimerization domain of B-SREBP-1 and a polyglutamic acid sequence that replaces the basic region. A-SREBP-1 heterodimerizes with either B-SREBP-1 or B-SREBP-2, and both heterodimers are more stable than B-SREBP-1 bound to DNA. Circular dichroism thermal denaturation studies show that the B-SREBP-1-A-SREBP-1 heterodimer is -9.8 kcal mol-1 dimer -1 more stable than the B-SREBP-1 homodimer. EMSA assays demonstrate that A-SREBP-1 can inhibit the DNA binding of either B-SREBP-1 or B-SREBP-2 in an equimolar competition but does not inhibit the DNA binding of the three B-HLH-ZIP proteins MAX, USF, or MITF, even at 100 molar eq. Chimeric proteins containing the HLH domain of SREBP-1 and the leucine zipper from either MAX, USF, or MITF indicate that both the HLH and leucine zipper regions of SREBP-1 contribute to its dimerization specificity. Transient co-transfection studies demonstrate that A-SREBP-1 can inhibit the transactivation of SREBP-1 and SREBP-2 but not USF. A-SREBP-1 may be useful in metabolic diseases where SREBP family members are overexpressed.

Original languageEnglish
Pages (from-to)11863-11874
Number of pages12
JournalJournal of Biological Chemistry
Volume279
Issue number12
DOIs
StatePublished - Mar 19 2004

Funding

FundersFunder number
National Childhood Cancer Registry – National Cancer InstituteZ01BC005271

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Cell Biology

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