Identification and regulation of novel PPAR-gamma splice variants in human THP-1 macrophages.
We have previously identified four novel isoforms of PPAR-gamma transcripts in monkey macrophages (J. Zhou, K.M. Wilson, J.D. Medh, Genetic analysis of four novel peroxisome proliferator receptor-gamma splice variants in monkey macrophages. Biochem. Biophys. Res. Commun., 293 (2002) 274-283). The purpose of this study was to ascertain that these isoforms are also present in humans. Specific primers were designed to amplify individual isoform transcripts. The presence of PPAR-gamma4, PPAR-gamma5, and PPAR-gamma7 transcripts in human THP-1 macrophages was confirmed by RT-PCR and sequencing. A transcript corresponding to PPAR-gamma6 was not detected. The presence of novel full-length transcripts and protein was also ascertained by Northern and Western blot analysis. Treatment of THP-1 cells with 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) resulted in more than 20% induction in the expression of PPAR-gamma5 and PPAR-gamma7 transcripts by both Northern blot analysis and RT-PCR. Another PPAR-gamma ligand, troglitazone, induced expression of only PPAR-gamma5. Both ligands inhibited the expression of PPAR-gamma1 and PPAR-gamma2. Additionally, 15d-PGJ2 and troglitazone increased the level of apolipoprotein E transcript by 60% but decreased lipoprotein lipase expression by 15% in THP-1 cells. The differential regulation of PPAR-gamma transcripts suggests that each transcript isoform may contribute to macrophage function.
Chen
Ye
Y
Department of Chemistry and Biochemistry, Sc3112B, California State University at Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA.
Jimenez
Anna R
AR
Medh
Jheem D
JD
D017398:Alternative Splicing; D001057:Apolipoproteins E / Q000235:genetics; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008071:Lipoprotein Lipase / Q000235:genetics; D008264:Macrophages / Q000378:metabolism*; D047495:PPAR gamma / Q000032:analysis* / Q000235:genetics; D020033:Protein Isoforms / Q000032:analysis / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis
D001057:Apolipoproteins E; D047495:PPAR gamma; D020033:Protein Isoforms; D012333:RNA, Messenger; D008071:Lipoprotein Lipase