Kanayama, T., Arito, M., So, K., Hachimura, S., Inoue, J. and Sato, R.
Notes: To explore the interaction of liver receptor homolog (LRH)-1, a known suppressor of sterol regulatory element-binding protein (SREBP) transcriptional activity, human LRH-1 was reverse transcribed then amplified by PCR from total RNA from HepG2 cells. The amplification product was ligated into the pTargeT™ Mammalian Expression Vector to create pTarget-LRH1. For reporter experiments, a PCR fragment that encompassed the 1.3kb 5’-promoter region of the human small heterodimer partner (SHP) gene was cloned into the pGL3-Basic Vector (designated pSRB). The pGL3-Promoter Vector was used to construct pLRHREx3, which contains three LRH-1 response elements, and the insert was generated using synthetic oligonucleotides. HEK293 cells were cotransfected with 0.2µg of a promoter-firefly luciferase construct, 0.1µg of a SREBP expression plasmid, 10ng of phRL-TK Vector and 0.2 or 0.6µg of pTarget-LRH1. Alternatively, the cotransfected plasmids were 0.2µg of pSHP, 0.1µg of pTarget-LRH1, 10ng of phRL-TK Vector and 0.2 or 0.6µg of a SREBP expression plasmid. The pLRHREx3 construct (0.2µg) was cotransfected with 0.1µg of a LRH-1 expression plasmid, 0.2µg of pCMXPGC-1α (peroxisome proliferator activated receptor γ coactivator-1α), 10ng of phRL-TK Vector, and 0.1 or 0.3µg of a pSREBP expression vector in HEK 293 cells. Luciferase expression was assayed 48 hours post-transfection using the Dual-Luciferase® Assay Reporter System. To express SREBPs and LRH-1 in vitro, inserts were ligated into the pTNT™ Vector, synthesized using the TNT® Coupled Transcription/Translation System with radiolabeled methionine. Ten microliters of the 35S-labelled protein was then used in a GST-pulldown assay. (3692)