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Regulation of apo A-IV transcription by lipid in newborn swine is associated with a promoter DNA-binding protein

Authors :
Heng Wang
Songmei Meng
Ying Yao
Dennis Black
Song Lu
Xiangying Cheng
Source :
American Journal of Physiology-Gastrointestinal and Liver Physiology. 284:G248-G254
Publication Year :
2003
Publisher :
American Physiological Society, 2003.

Abstract

Dietary lipid acutely upregulates apolipoprotein (apo) A-IV expression by sevenfold at the pretranslational level in neonatal swine jejunum. To determine the mechanism of this regulation, two-day-old female swine received intraduodenal infusions of low- and high-triacylglycerol (TG) isocaloric diets for 24 h. Nuclear runoff assay confirmed apo A-IV gene transcriptional regulation by the high-TG diet. Footprinting analysis using the swine apo A-IV proximal promoter sequence (+14 to −246 bp) demonstrated three regions protected by the low-TG extracts. Of these three motifs, only ACCTTC showed 100% homology to the human sequence and was further studied. EMSA was performed using probes containing wild-type (WT) and mutant (M) motifs. A shift was noted with the low-TG nuclear extracts with the WT probe but not with the M probe. Excess unlabeled free WT probe competed out the shift, whereas the M probe did not. No significant shift occurred with either probe using high-TG extracts. These results suggest that a repressor protein binds to the ACCTTC motif and becomes unbound during lipid absorption, allowing transcriptional activation of the apo A-IV gene in newborn swine small intestine.

Details

ISSN :
15221547 and 01931857
Volume :
284
Database :
OpenAIRE
Journal :
American Journal of Physiology-Gastrointestinal and Liver Physiology
Accession number :
edsair.doi.dedup.....e5643b3c18fd0b692dba2df70a60478c
Full Text :
https://doi.org/10.1152/ajpgi.00391.2002