期刊
MOLECULAR AND CELLULAR BIOLOGY
卷 23, 期 1, 页码 259-271出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/MCB.23.1.259-271.2003
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资金
- NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES [R01DK043673, P30DK034928, T32DK007542, R01DK052870] Funding Source: NIH RePORTER
- NIDDK NIH HHS [T32-DK07542, R01 DK043673, DK52870, T32 DK007542, P30 DK034928, DK43673, P30-DK34928] Funding Source: Medline
The basic helix-loop-helix protein BETA2/NeuroD activates transcription of the secretin gene and is essential for terminal differentiation of secretin-producing enteroendocrine cells. However, in heterodimeric complexes with its partner basic helix-loop-helix proteins, BETA2 does not appear to be a strong activator of transcription by itself. Mutational analysis of a proximal enhancer in the secretin gene identified several cis-acting elements in addition to the E-box binding site for BETA2. We identified by expression cloning the zinc finger protein RREB-1, also known to exist as a longer form, Finb, as the protein binding to one of the mutationally sensitive elements. Finb/RREB-1 lacks an intrinsic activation domain and by itself did not activate secretin gene transcription. Here we show that Finb/RREB-1 can associate with BETA2 to enhance its transcription-activating function. Both DNA binding and physical interaction of Finb/RREB-1 with BETA2 are required to potentiate transcription. Thus, Finb/RREB-1 does not function as a classical activator of transcription that recruits an activation domain to a DNA-protein complex. Finb/RREB-1 may be distinguished from coactivators, which increase transcription without sequence- specific DNA binding. We suggest that Finb/RREB-1 should be considered a potentiator of transcription, representing a distinct category of transcription-regulating proteins.
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