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.
Department of Chemistry and Biochemistry, Sc3112B, California State University at Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA.
Ye
Y
Chen
Anna R
AR
Jimenez
Jheem D
JD
Medh
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