The main objective of this thesis is to contribute to our understanding of the regulation of brown adipose gene expression by examining the transcriptional regulation of the two key brown adipogenic genes, UCPl and PGCla during the initial stage of differentiation in a model brown adipocyte cell line. The principal findings were that UCP land PGC 1 a expression was induced by both forskolin and rosiglitazone, and that combination of these drugs produced a synergistic increase which required the full length promoters. These effects on UCPl and PGCla expression were partially suppressed by PKA and PPARy antagonists and results suggested that there is a cross-talk between PKA and PPARy signalling pathways. C~anges in brown adipogenic gene expression similarly provided evidence of cross-talk between PKA and PPARy signalling pathways which may explain the mechanism responsible for the synergistic effects offorskolin and rosiglitazone on UCPl expression. PPARy and CIEBPP, but not PGC 1 a overexpression, increased basal and stimulated UCP 1 mRNA. Similar results were observed with the 3.lkb UCPl-Luc reporter and co-overexpression ofPPARy with PGC 1 a markedly upregulated UCP 1 transcription in response to either forskolin or rosiglitazone. PGCla mRNA was increased in response to C/EBPP, but not PPARy overexpression and these results were confirmed using the 2.6kb PGCla-Luc reporter. PGC 1 a transcription was further up-regulated by co-overexpression of C/EBPP with PPARy in response to either forskolin or rosiglitazone. RIPl40 overexpression inhibited the effect of PG Cl a on rosiglitazone stimulated 3.lkb UCPl-Luc promoter activity. The results suggests that there are differences in transcriptional regulation between UCP 1 and PGCla promoters which indicate that the synergistic effect of cAMP and PPARy ligand stimulation on UCPl expression is a direct results of control of the PPRE and CRE on the UCPl promoter rather than indirect control though the PGCla promoter. vi
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:575158 |
| Date | January 2011 |
| Creators | Chen, Hsiang Yin |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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