Characterization of the Chicken Apolipoprotein A-I Gene 5′-Flanking Region

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Abstract
Apolipoprotein A-I (apoA-I) is a major protein component of plasma high-density lipoprotein in all species studied, and plays an important role in cholesterol homeostasis. In an earlier study, we cloned and structurally characterized the chicken apoA-I gene. In this study, the 5′-flanking region of the chicken apoA-I gene was sequenced and functionally characterized. Sequence analysis of the 510-nucleotide 5′ upstream region revealed the presence of TATA and CCAAT boxes. In addition, we identified binding sites for several transcription factors such as S1l, A1I, and NFI.2. When the ′' fragment was ligated into a promoterless CAT vector and transfected into a chicken hepatocarcinoma cell line (LMH), the bacterial chloramphenicol acetyl transferase (CAT) gene was expressed, suggesting transcriptional regulation is associated with this region. Transfection studies with other ′' deletion constructs revealed that the sequence spanning the region–-82 to +87 contained the major transcriptional activity. DNase I footprinting, gel retardation, and Southwestern blot analyses showed that the fragment interacts with nuclear proteins.