Cloning of Ki-ras and Ha-ras cDNAs from the hermaphroditic fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) and its expression after exposure to 4-nonylphenol.
Previous studies on ras proto-oncogene genes in fish have been focused on chemical-associated carcinogenesis, and the expression of fish ras genes was not well-characterized. We investigated Ki- and Ha-ras genes from the hermaphroditic fish Rivulus marmoratus to understand better their expression patterns in specific tissues, as well as their responses to endocrine-disrupting chemicals such as 4-nonylphenol (4-NP). By investigating expression patterns, we found that the R. marmoratus Ki-ras (Rm Ki-ras) gene showed an alternative splicing event between exons 4A and 4B according to tissue types, which is different from the expression pattern of mammalian Ki-ras genes. In the Rm Ki-ras gene, there were two different expressed types, with exons 1-2-3-4A-4B (long form) and with exons 1-2-3-4B (short form). In the Rm Ki-ras gene, the long form was expressed strongly in the gonad and intestine, and the short form was expressed ubiquitously, except for a low level of expression in the liver. Following 4-NP exposure (300 microg/L), the Rm Ki-ras long form in the liver was significantly expressed, while it was expressed moderately in the ovaries. However, the Rm Ha-ras gene was significantly over-expressed in the brain, while its expression in the gonad was down-regulated. In relation to these modulations after 4-NP exposure, we searched the Rm Ha- and Ki-ras promoter regions and found several ERE-half sites, that may be involved in the modulation of ras gene expression following 4-NP exposure. These genes could be applicable as new biomarker genes for assessing exposure to endocrine-disrupting chemicals (EDCs). Further, this implies the disturbance of ras-dependent signal transduction following EDC exposure.
Lee
Young-Mi
YM
Department of Molecular and Environmental Bioscience, Graduate School, Hanyang University, Seoul 133-791, South Korea.
Jung
Sang-Oun
SO
Seo
Jung Soo
JS
Yoon
Yong-Dal
YD
Lee
Jae-Seong
JS
D017398:Alternative Splicing; D000818:Animals; D003001:Cloning, Molecular; D003532:Cyprinodontiformes / Q000235:genetics*; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D004781:Environmental Exposure; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling / Q000379:methods; D011905:Genes, ras / Q000187:drug effects* / Q000235:genetics; D008969:Molecular Sequence Data; D010636:Phenols / Q000633:toxicity*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014874:Water Pollutants, Chemical / Q000633:toxicity
D017931:DNA Primers; D018076:DNA, Complementary; D010636:Phenols; D014874:Water Pollutants, Chemical; C041594:4-nonylphenol