Cloning and functional analysis of human acyl coenzyme A: Cholesterol acyltransferase1 gene P1 promoter

Acyl-coenzyme A: cholesterol acyltransferase 1 (ACAT1) catalyzes the conversion of free cholesterol (FC) to cholesterol ester. The human ACAT1 gene P1 promoter has been cloned. However, the activity and specificity of the ACAT1 gene P1 promoter in diverse cell types remains unclear. The P1 promoter fragment was digested with KpnI/XhoI from a P1 promoter cloning vector, and was subcloned into the multiple cloning site of the Firefly luciferase vector pGL3‑Enhancer to obtain the construct P1E‑1. According to the analysis of biological information, the P1E‑1 plasmid was used to generate deletions of the ACAT1 gene P1 promoter with varying 5' ends and an identical 3' end at +65 by polymerase chain reaction (PCR). All the 5'‑deletion constructs of the P1 promoter were identified by PCR, restriction enzyme digestion mapping and DNA sequencing. The transcriptional activity of each construct was detected after transient transfection into THP‑1, HepG2, HEK293 and Hela cells using DEAE‑dextran and Lipofectamine 2000 liposome transfection reagent. Results showed that the transcriptional activity of the ACAT1 gene P1 promoter and deletions of P1 promoter in THP‑1 and HepG2 cells was higher than that in HEK293 and HeLa cells. Moreover, the transcriptional activity of P1E‑9 was higher compared with those of other deletions in THP‑1, HepG2, HEK293 and HeLa cells. These findings indicate that the transcriptional activity of the P1 promoter and the effects of deletions vary with different cell lines. Thus, the P1 promoter may drive ACAT1 gene expression with cell‑type specificity. In addition, the core sequence of ACAT1 gene P1 promoter was suggested to be between -125 and +65 bp.