Expression of GRP78 Enhance-CAT Fusion Constructs Microiniected into Xenopus Iceuis Oocytes

Xenopus 난자에 미세주입된 GRP78 Enhancer-CAT 이형접합자의 발현

Microiniection of genes Into Xenopus laeuis oocvtes in highly useful in the annvsis of gene regulation, since a large number of oocvtes can be injected in a relatively short time. The GRP78 enhancer has been identified to a 291-bp fragment that spans a region of GRP78 promoter between -378 and -87 (Lin et at., 1986: Kim and Lee, 1989). We examined whether this GRP78 enhancer is effective in directing expression of heterologous gene in Xenopus laeuis oocytes. The chloramphenicol acetvltransferase (CAT) fusion constructs containing the GRP78 promoter and the SV4O early promoter were constructed and were injected into nuclei of Xencpus laeuis oocvtes. The recipient oocvtes were then assayed for CAT activity. The fusion constructs exhibited higher activity as compared to SV40 promoter tested here. The GRP78 enhancer showed 8.5- to 9.2-fold enhancement over that of the SV4O promoter. The orientation of GRP78 enhancer with respect to the direction of CAT transcription unit had no significant effect. Thus, the GRP78 enhancer is a viable candidate for the construction of expression system for use in Xenopus laevss oocvtes and will be important for the studY of a gene expression throughout development.