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. 2009 Apr 29;83(14):7202–7209. doi: 10.1128/JVI.00076-09

FIG. 4.

FIG. 4.

The KSHV RTA promoter contains response elements for XBP-1 and HIF-1α and can respond to both. (A) Schematic of the predicted HREs in the KSHV RTA promoter region (adapted from reference 4). (B) Schematic of reporter plasmids pRpluc1-3087+s containing a 3-kb sequence upstream of the RTA transcriptional start site and a 1-kb splicing sequence of RTA that drives the expression of firefly luciferase (FL) (4) as well as truncated promoters named pRpluc1115-1327 (HRE2 only) and pRpluc1-550 XRE (HRE4 only). (B) A fixed amount of the reporter plasmids was transfected into HEK 293T cells, together with pIG (empty vector control; ↓), RTA-expressing (pCMV-RTA; black bars), XBP-1s-expressing (pXBP-sIG; striped bars), or HIF-1α-expressing (pHIF-1αIG; white bars) plasmids, normalized by plasmid copy number. Promoter activity levels are expressed as log relative light units (logRLU) relative to the levels for the reporter plus the pIG control plasmid. Means and standard errors are from three independent transfections. HIF-1α acts on all reporters containing HRE2 and HRE4 while XBP-1s acts on the full-length and HRE4-only promoter but not HRE2 only.