Abstract
The cDNA and genomic DNA of zebrafish (Danio rerio) protein kinase Cμ (PKCμ), with its promoter region, were obtained. The 508–amino acid zebrafish PKCμ has 86.17% similarity to human PKCμ. Real-time reverse-transcription polymerase chain reaction analysis with starvation and hormonal treatment found significant differences between the control group and the experimental group after 14 days of starvation. After injecting insulin-like growth factor II (IGF-II), growth hormone (GH), insulin, or human chorionic gonadotropin, significant differences were observed between the control and experimental groups 24 h after treatment. After injecting the gonadotropin-releasing hormone or luteotropin-releasing hormone, significant differences were seen between the control and experimental groups 15 h after treatment. These results suggest that in vivo PKCμ expression is regulated by the insulin family or by the GH, but other sex hormones produced a significant expression level more quickly than the insulin family and GH. The zebrafish PKCμ gene is located on zebrafish chromosome 17 and consists of 16 exons. A 2.6 kilobase pair on the 5′ flanking region displayed maximal promoter activity in the zebrafish liver (ZFL) cell line after treatment with IGF-I, IGF-II, and GH. However, a 1.6 kilobase pair on the 5′ flanking region displayed maximal promoter activity in the HeLa cell line after treatment with IGF-I, IGF-II, and GH. Finally, PKCμ may have important nuclear effects on cell growth and may involve nuclear localization. By transiently transfecting ZFL cells with various zebrafish PKCμ segments, we identified a nuclear localization signal: the amino acid sequence between amino acids 206 and 209 was able to predominantly direct enhanced green fluorescence protein (EGFP) into the nucleus, whereas a deletion of this motif abrogated the nuclear localization property.
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