Hepatic and extrahepatic expression of vitellogenin genes in the zebrafish, Danio rerio
Vitellogenins (Vtgs) are yolk precursor proteins in oviparous species and are cleaved into three portions–lipovitellin I (LVI), phosvitin (PV), and lipovitellin II (LVII)–in oocytes in vertebrates. In the present study, we found that the zebrafish genome contains at least seven vtg genes ( vtg1–7) e...
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Veröffentlicht in: | Gene 2005-08, Vol.356, p.91-100 |
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Zusammenfassung: | Vitellogenins (Vtgs) are yolk precursor proteins in oviparous species and are cleaved into three portions–lipovitellin I (LVI), phosvitin (PV), and lipovitellin II (LVII)–in oocytes in vertebrates. In the present study, we found that the zebrafish genome contains at least seven
vtg genes (
vtg1–7) encoding heterogeneous vitellogenins with three distinct types of Vtgs: type I (Vtg1, 4–7) contains all the three major portions but lacks the C-terminal half of LVII; type II (Vtg2) is the only one including intact three portions; type III (Vtg3) lacks both PV and the LVII C-terminal half. The seven
vtgs were located in two different chromosomes: one (
vtg3) in LG11 and the rest closely linked in LG22, probably arisen from local gene duplication events. All of the seven
vtgs are predominantly expressed in female liver and can be induced in male liver by 17β-estradiol (E
2). The level of
vtg1 mRNA was about 100× and 1000× higher than those of
vtg2 and
vtg3 mRNAs. We also found
vtg mRNAs in several non-liver tissues, but the expression level is generally <
10% of that in the liver. In situ hybridization experiments confirmed that the extrahepatic expression was actually in adipocytes associated with several organs such as the intestine, ovary, and E
2-induced testis. |
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ISSN: | 0378-1119 1879-0038 |
DOI: | 10.1016/j.gene.2005.03.041 |