title: PPARγ and NF-κB regulate the gene promoter activity of their shared repressor, TNIP1.
abstract: Human TNFAIP3 interacting protein 1 (TNIP1) has diverse functions including support of HIV replication through its interaction with viral Nef and matrix proteins, reduction of TNFα-induced signaling through its interaction with NF-κB pathway proteins, and corepression of agonist-bound retinoic acid receptors and peroxisome proliferator-activated receptors (PPAR). The wide tissue distribution of TNIP1 provides the opportunity to influence numerous cellular responses in these roles and defining control of TNIP1 expression would be central to improved understanding of its impact on cell function. We cloned 6kb of the human TNIP1 promoter and performed predictive and functional analyses to identify regulatory elements. The promoter region proximal to the transcription start site is GC-rich without a recognizable TATA box. In contrast to this proximal ~500bp region, 6kb of the promoter increased reporter construct constitutive activity over five-fold. Throughout the 6kb length, in silico analysis identified several potential binding sites for both constitutive and inducible transcription factors; among the latter were candidate NF-κB binding sequences and peroxisome proliferator response elements (PPREs). We tested NF-κB and PPAR regulation of the endogenous TNIP1 gene and cloned promoter by expression studies, electrophoretic mobility shift assays, and chromatin immunoprecipitations. We validated NF-κB sites in the TNIP1 promoter proximal and distal regions as well as one PPRE in the distal region. The ultimate control of the TNIP1 promoter is likely to be a combination of constitutive transcription factors and those subject to activation such as NF-κB and PPAR.
authors: Graduate Program in Pharmacology & Toxicology, University of Connecticut, Storrs, CT 06269-3092, USA. igor.gurevich@huskymail.uconn.edu
authors: Igor
authors: I
authors: Gurevich
authors: Carmen
authors: C
authors: Zhang
authors: Priscilla C
authors: PC
authors: Encarnacao
authors: Charles P
authors: CP
authors: Struzynski
authors: Sarah E
authors: SE
authors: Livings
authors: Brian J
authors: BJ
authors: Aneskievich
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000235:genetics* / Q000378:metabolism; D047495:PPAR gamma / Q000235:genetics* / Q000378:metabolism; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D020218:Response Elements / Q000235:genetics; D015398:Signal Transduction; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D016328:NF-kappa B; D047495:PPAR gamma; D047492:Peroxisome Proliferator-Activated Receptors; C117046:TNIP1 protein, human; D051996:Transcription Factor RelA