Fig. 4.

Increase in c-Fos promoter activity in NGF-differentiated PC12 cells, preproglucagon promoter activity in STC-1 cells, neuropeptide Y 1 receptor (NPY1R) promoter activity in hBRIE380i cells, and c-Fos expression in hippocampal cells by peptone-activated LPA5. The respective cells were transfected with the luciferase reporter construct and LPA5 cDNA or the empty vector. A: c-Fos promoter is from −341 to +16 bp relative to the transcription start site; preproglucagon promoter is from −1,054 to −35; NPY1R promoter is from −1,000 to +1. B: RT-PCR of c-Fos expression was greater in response to peptone (P) than to LPA (L) or FPP (F), compared with the empty vector control (C) in mucosal hBRIE380i cells. Cells were serum starved for 12 h and treated with 10 μM LPA or 50 mg/ml peptone for 6 h. Bars are means (relative to vector) ± SD (n = 3). C: PC12 cells differentiated by NGF. D: primary mouse hippocampal neurons were transfected with 6 μg of either LPA5 cDNA or the empty vector. Cells were allowed to recover for 24 h, and, after being serum starved for 12 h, the cells were treated with either 50 mg/ml peptone or 10 μM LPA in 50% Iscove's Modified Dulbecco's Medium/0.1% fatty acid-free bovine serum albumin for additional 6 h. The expression of c-Fos was determined by semi-quantitative RT-PCR. LPA5 expression levels (E) in PC12 cells and hippocampal neurons (F) were determined by semiquantitative RT-PCR. Representative images of ethidium bromide-stained agarose gels of the amplified fragments are depicted. Bars are means ± SD (n = 3). *P < 0.05 relative to bar 1 of the corresponding (solid and open).