摘要
Visual system homeobox-1 （vsxl） is important in retinal progenitor proliferation, differentiation, and function maintenance of bipolar cells in vertebrates. Recent study in Xenopus laevis has shown that vsxl 3＇ untranslated region （3＇ UTR） can mediate cell-specific translation of vsxl mRNA in the bipolar cells of the retinal inner nuclear layer （INL）. vsxl is also transcribed at the early developmental stages prior to eye formation and its spatiotemporal expression patterns are conserved in all the examined vertebrates. In order to determine whether the vsxl 3＇ UTR has a role in regulating the spatiotemporal expression of vsxl during early embryogenesis, we constructed a vsxl UTR-controlled green fluorescent protein （GFP） reporter gene system and examined the GFP expression pattern in goldfish, Carassius auratus, at different developmental stages, Our results indicated that both the vsxl 5＇ UTR and the vsxl 3＇ UTR remarkably repressed GFP expression at transcription level but did not regulate tissue-specific translation at early developmental stages. GFP protein was ubiquitously expressed in the embryos injected with GFP-sensors containing vsxl UTRs before 60 h post-fertilization （hpf）. From hatching stage （72 hpf） onwards, however, GFP protein was specifically expressed in the bipolar cells of the retinal 1NL in the vsxl 3＇UTR-GFP-sensor embryos, but was still ubiquitously expressed in the embryos injected with GFP-sensor lacking vsxl 3＇ UTR. These observations showed a significant difference of vsxl 3＇ UTR-mediated translation between early and late developmental stages and suggested that vsxl 3＇ UTR might not be involved in regulating the spatiotemporal expression of vsxl until hatching stage during embryogenesis.
Visual system homeobox-1 （vsxl） is important in retinal progenitor proliferation, differentiation, and function maintenance of bipolar cells in vertebrates. Recent study in Xenopus laevis has shown that vsxl 3＇ untranslated region （3＇ UTR） can mediate cell-specific translation of vsxl mRNA in the bipolar cells of the retinal inner nuclear layer （INL）. vsxl is also transcribed at the early developmental stages prior to eye formation and its spatiotemporal expression patterns are conserved in all the examined vertebrates. In order to determine whether the vsxl 3＇ UTR has a role in regulating the spatiotemporal expression of vsxl during early embryogenesis, we constructed a vsxl UTR-controlled green fluorescent protein （GFP） reporter gene system and examined the GFP expression pattern in goldfish, Carassius auratus, at different developmental stages, Our results indicated that both the vsxl 5＇ UTR and the vsxl 3＇ UTR remarkably repressed GFP expression at transcription level but did not regulate tissue-specific translation at early developmental stages. GFP protein was ubiquitously expressed in the embryos injected with GFP-sensors containing vsxl UTRs before 60 h post-fertilization （hpf）. From hatching stage （72 hpf） onwards, however, GFP protein was specifically expressed in the bipolar cells of the retinal 1NL in the vsxl 3＇UTR-GFP-sensor embryos, but was still ubiquitously expressed in the embryos injected with GFP-sensor lacking vsxl 3＇ UTR. These observations showed a significant difference of vsxl 3＇ UTR-mediated translation between early and late developmental stages and suggested that vsxl 3＇ UTR might not be involved in regulating the spatiotemporal expression of vsxl until hatching stage during embryogenesis.
基金
supported by the National Science Foundation of China (No.30430370)
the State Key Basic Research Project of China (No.2004CB117401)
