title: A transgenic zebrafish model for monitoring xbp1 splicing and endoplasmic reticulum stress in vivo.
abstract: Accumulation of misfolded or unfolded proteins in the endoplasmic reticulum (ER) triggers ER stress that initiates unfolded protein response (UPR). XBP1 is a transcription factor that mediates one of the key signaling pathways of UPR to cope with ER stress through regulating gene expression. Activation of XBP1 involves an unconventional mRNA splicing catalyzed by IRE1 endonuclease that removes an internal 26 nucleotides from xbp1 mRNA transcripts in the cytoplasm. Researchers have taken advantage of this unique activation mechanism to monitor XBP1 activation, thereby UPR, in cell culture and transgenic models. Here we report a Tg(ef1α:xbp1δ-gfp) transgenic zebrafish line to monitor XBP1 activation using GFP as a reporter especially in zebrafish oocytes and developing embryos. The Tg(ef1α:xbp1δ-gfp) transgene was constructed using part of the zebrafish xbp1 cDNA containing the splicing element. ER stress induced splicing results in the cDNA encoding a GFP-tagged partial XBP1 without the transactivation activation domain (XBP1Δ-GFP). The results showed that xbp1 transcripts mainly exist as the spliced active isoform in unfertilized oocytes and zebrafish embryos prior to zygotic gene activation at 3 hours post fertilization. A strong GFP expression was observed in unfertilized oocytes, eyes, brain and skeletal muscle in addition to a weak expression in the hatching gland. Incubation of transgenic zebrafish embryos with (dithiothreitol) DTT significantly induced XBP1Δ-GFP expression. Collectively, these studies unveil the presence of maternal xbp1 splicing in zebrafish oocytes, fertilized eggs and early stage embryos. The Tg(ef1α:xbp1δ-gfp) transgenic zebrafish provides a useful model for in vivo monitoring xbp1 splicing during development and under ER stress conditions.
authors.affiliation: Institute of Marine and Environmental Technology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Shandong Medicinal and Biotechnology Center, Shandong Academy of Medical Sciences, Jinan 250062, Shandong Province, China.
authors.forename: Junling
authors.initials: J
authors.lastname: Li
authors.affiliation: Institute of Marine and Environmental Technology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Center for Biomedical Engineering and Technology, Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of cell Biology and Molecular genetics, University of Maryland, College Park, MD 20742, USA.
authors.forename: Lian-Yong
authors.initials: LY
authors.lastname: Gao
authors.affiliation: Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat 88112, Israel.
authors.forename: Angelo
authors.initials: A
authors.lastname: Colorni
authors.affiliation: Israel Oceanographic and Limnological Research, National Center for Mariculture, Eilat 88112, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Ucko
authors.affiliation: Center for Biomedical Engineering and Technology, Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA. Electronic address: sfang@umaryland.edu.
authors.forename: Shengyun
authors.initials: S
authors.lastname: Fang
authors.affiliation: Institute of Marine and Environmental Technology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA. Electronic address: sdu@som.umaryland.edu.
authors.forename: Shao Jun
authors.initials: SJ
authors.lastname: Du
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000235:genetics; D059865:Endoplasmic Reticulum Stress / Q000235:genetics*; D015870:Gene Expression / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D009865:Oocytes / Q000502:physiology; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D056811:Unfolded Protein Response / Q000235:genetics; D015027:Zebrafish / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors
keywords: ER stress; Endoplasmic reticulum; Transgenic zebrafish model; XBP1