RESUMO
2'-O,4'-C-methylene bridged nucleic acid (2',4'-BNA) is a nucleic acid analogue that has high affinity binding to its complementary RNA. Peroxisome proliferator-activated receptor (PPAR) y belongs to the nuclear hormone receptor superfamily and is a drug target in the treatment of type 2 diabetes. Here, we show the antisense effects of 2',4'-BNA oligonucleotides against PPARy in the human monocytic leukaemia cell line THP-1 and the human colorectal tumor cell line HCT116.
Assuntos
Hipoglicemiantes/química , Hipoglicemiantes/farmacologia , Oligonucleotídeos Antissenso/farmacologia , PPAR gama/genética , Hidrocarbonetos Aromáticos com Pontes/química , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Linhagem Celular Tumoral , Expressão Gênica/efeitos dos fármacos , Humanos , Oligonucleotídeos Antissenso/química , PPAR gama/metabolismoRESUMO
Liver X receptor alpha (LXRalpha) is a member of the nuclear receptor superfamily that is activated by oxysterols, and plays a pivotal role in regulating the metabolism, transport and uptake of cholesterol. Here, we demonstrate that LXRalpha also regulates the low-density lipoprotein receptor (LDLR) gene, which mediates the endocytic uptake of LDL cholesterol in the liver. An LXR agonist induced the expression of LDLR in cultured hepatoblastoma cells. Moreover, the LDLR promoter contained an LXR response element that was recognized by LXRalpha/RXRalpha (retinoid X receptor alpha) heterodimers in hepatoblastoma cells. These results suggest a novel pathway whereby LXRalpha might modulate cholesterol metabolism.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores de LDL/metabolismo , Animais , Linhagem Celular Tumoral , Colesterol/metabolismo , Proteínas de Ligação a DNA/agonistas , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Dimerização , Humanos , Receptores X do Fígado , Receptores Nucleares Órfãos , Regiões Promotoras Genéticas , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores Citoplasmáticos e Nucleares/química , Receptores Citoplasmáticos e Nucleares/genética , Receptores de LDL/genética , Receptor X Retinoide alfa/química , Receptor X Retinoide alfa/genética , Receptor X Retinoide alfa/metabolismoRESUMO
BACKGROUND: Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors and commonly play an important role in the regulation of lipid homeostasis. To identify human PPARs-responsive genes, we established tetracycline-regulated human hepatoblastoma cell lines that can be induced to express each human PPAR and investigated the gene expression profiles of these cells. RESULTS: The expression of each introduced PPAR gene was investigated using the various concentrations of doxycycline in the culture media. We found that the expression of each PPAR subtype was tightly controlled by the concentration of doxycycline in these established cell lines. DNA microarray analyses using these cell lines were performed with or without adding each subtype ligand and provided much important information on the PPAR target genes involved in lipid metabolism, transport, storage and other activities. Interestingly, it was noted that while ligand-activated PPARdelta induced target gene expression, unliganded PPARdelta repressed these genes. The real-time RT-PCR was used to verify the altered expression of selected genes by PPARs and we found that these genes were induced to express in the same pattern as detected in the microarray analyses. Furthermore, we analysed the 5'-flanking region of the human adipose differentiation-related protein (adrp) gene that responded to all subtypes of PPARs. From the detailed analyses by reporter assays, the EMSAs, and ChIP assays, we determined the functional PPRE of the human adrp gene. CONCLUSION: The results suggest that these cell lines are important tools used to identify the human PPARs-responsive genes.
