title: Induction of hormone-sensitive lipase/cholesteryl esterase gene expression by C/EBPα independently of the PKA pathway in the adrenocortical Y-1 cells.
abstract: The effect of C/EBPα on the expression of LIPE gene encoding hormone-sensitive lipase/cholesteryl esterase (HSL) was investigated in Y-1 CCL79 cells. It was found that transfection of these cells with the vector overexpressing C/EBPα increased both the level of LIPE transcript, measured by RT-qPCR, and the luminesce emitted by luciferase reporter gene fused to the -2150 fragment of LIPE promoter. Activation of adenylyl cyclase by forskolin resulted in 2.5-fold increase in the intensity of luminescence and over 3-fold increase in luminescence was observed when the cells were cotransfected with the vector overexpressing C/EBP. The incubation of C/EBP-cotransfected cells with forskolin caused over 6-fold increase in the intensity of luminescence, suggesting that the effects of C/EBPα and forskolin are additive. The analysis of sequence of the proximal LIPE promoter showed multiple binding sites for various transcription factors including C/EBPα site, which is located between nucleotides -46 bp and -59 bp. When the Y-1 cells were transfected with the recombinant vector containing -60 bp fragment of LIPE promoter fused to the luciferase reporter gene and were cotransfected with the vector overexpressing C/EBPα, the luminescence increases about 9-fold indicating that C/EBPα stimulates the expression of LIPE by reacting with its response element. The results indicate that C/EBPα stimulates the expression of LIPE independently of the PKA pathway by binding to a response element situated within the -60 bp fragment of LIPE promoter. This suggests that C/EBPα might be involved in the regulation of LIPE expression and thus cholesterol supply for steroid hormone synthesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Poznan University of Medical Sciences, Poznan, Poland.
authors.forename: M T
authors.initials: MT
authors.lastname: Czajkowski
authors.affiliation: Department of Biochemistry and Molecular Biology, Poznan University of Medical Sciences, Poznan, Poland. Electronic address: mholysz@ump.edu.pl.
authors.forename: M
authors.initials: M
authors.lastname: Holysz
authors.affiliation: Department of Biochemistry and Molecular Biology, Poznan University of Medical Sciences, Poznan, Poland.
authors.forename: W H
authors.initials: WH
authors.lastname: Trzeciak
mesh_terms: D000302:Adrenal Cortex / Q000166:cytology* / Q000378:metabolism*; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism*; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D020869:Gene Expression Profiling; D008049:Lipase / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D060888:Real-Time Polymerase Chain Reaction; D002787:Sterol Esterase / Q000235:genetics* / Q000378:metabolism
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; D017868:Cyclic AMP-Dependent Protein Kinases; D002787:Sterol Esterase; D008049:Lipase
keywords: C/EBPα; LIPE induction; PKA; Y-1 cells