Slc39a7/zip7 Plays a Critical Role in Development and Zinc Homeostasis in Zebrafish

PLOS ONE, Dec 2019

Background Slc39a7/Zip7, also known as Ke4, is a member of solute carrier family 39 (Slc39a) and plays a critical role in regulating cell growth and death. Because the function of Zip7 in vivo was unclear, the present study investigated the function of zip7 in vertebrate development and zinc metabolism using zebrafish as a model organism. Principal Finding Using real-time PCR to determine the gene expression pattern of zip7 during zebrafish development, we found that zip7 mRNA is expressed throughout embryonic development and into maturity. Interestingly, whole mount in situ hybridization revealed that while zip7 mRNA is ubiquitously expressed until 12 hours post-fertilization (hpf); at 24 hpf and beyond, zip7 mRNA was specifically detected only in eyes. Morpholino-antisense (MO) gene knockdown assay revealed that downregulation of zip7 expression resulted in several morphological defects in zebrafish including decreased head size, smaller eyes, shorter palates, and shorter and curved spinal cords. Analysis by synchrotron radiation X-ray fluorescence (SR-XRF) showed reduced concentrations of zinc in brain, eyes, and gills of zip7-MO-injected embryos. Furthermore, incubation of the zip7 knockdown embryos in a zinc-supplemented solution was able to rescue the MO-induced morphological defects. Significance Our data suggest that zip7 is required for eye, brain, and skeleton formation during early embryonic development in zebrafish. Moreover, zinc supplementation can partially rescue defects resulting from zip7 gene knockdown. Taken together, our data provide critical insight into a novel function of zip7 in development and zinc homeostasis in vivo in zebrafish.

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Slc39a7/zip7 Plays a Critical Role in Development and Zinc Homeostasis in Zebrafish

Citation: Yan G, Zhang Y, Yu J, Yu Y, Zhang F, et al. ( Slc39a7/zip7 Plays a Critical Role in Development and Zinc Homeostasis in Zebrafish Guang Yan 0 Yuchao Zhang 0 Junlei Yu 0 Yu Yu 0 Fan Zhang 0 Zhuzhen Zhang 0 Aimin Wu 0 Xianghua Yan 0 Yi Zhou 0 Fudi Wang 0 Yann Gibert, Deakin School of Medicine, Australia 0 1 Group of Bio-Metal Metabolism, Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences , Shanghai , People's Republic of China, 2 College of Animal Sciences and Technology, Key Laboratory of Swine Genetics and Breeding, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China , 3 Schools of Life and Food Engineering, Nanchang University , Nanchang , China , 4 Stem Cell Program and Division of Hematology/Oncology Children's Hospital Boston and Dana-Farber Cancer Institute, Harvard Stem Cell Institute, Harvard Medical School , Boston, Massachusetts , United States of America Background: Slc39a7/Zip7, also known as Ke4, is a member of solute carrier family 39 (Slc39a) and plays a critical role in regulating cell growth and death. Because the function of Zip7 in vivo was unclear, the present study investigated the function of zip7 in vertebrate development and zinc metabolism using zebrafish as a model organism. Principal Finding: Using real-time PCR to determine the gene expression pattern of zip7 during zebrafish development, we found that zip7 mRNA is expressed throughout embryonic development and into maturity. Interestingly, whole mount in situ hybridization revealed that while zip7 mRNA is ubiquitously expressed until 12 hours post-fertilization (hpf); at 24 hpf and beyond, zip7 mRNA was specifically detected only in eyes. Morpholino-antisense (MO) gene knockdown assay revealed that downregulation of zip7 expression resulted in several morphological defects in zebrafish including decreased head size, smaller eyes, shorter palates, and shorter and curved spinal cords. Analysis by synchrotron radiation X-ray fluorescence (SRXRF) showed reduced concentrations of zinc in brain, eyes, and gills of zip7-MO-injected embryos. Furthermore, incubation of the zip7 knockdown embryos in a zinc-supplemented solution was able to rescue the MO-induced morphological defects. Significance: Our data suggest that zip7 is required for eye, brain, and skeleton formation during early embryonic development in zebrafish. Moreover, zinc supplementation can partially rescue defects resulting from zip7 gene knockdown. Taken together, our data provide critical insight into a novel function of zip7 in development and zinc homeostasis in vivo in zebrafish. - Funding: This work was supported by research grants from the Ministry of Science and Technology of China (973 Program) (grant numbers 2009CB941400, 2011CB966200 to FW); the National Natural Science Foundation of China (grant numbers 10979071, 30970665, 31030039 to FW, 30901193 to YY); Science & Technology Commission of Shanghai Municipality grant (grant number 10JC1416800 to FW) and Chinese Academy of Sciences Hundred Talents Program (grant number KSCX2-YW-R-141 to FW). FW is a scholar of the Hundred Talents Program of the Chinese Academy of Sciences. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. . These authors contributed equally to this work. Zinc is an essential trace element required for DNA synthesis, cell division, regulation of transcription, and protein synthesis. Approximately 2000 enzymes use zinc as a catalytic cofactor [1], and zinc binding motifs are found in up to 10% of the proteins encoded by the human genome [2] including zinc-fingercontaining proteins, the most abundant protein superfamily in the mammalian genome. In this regard, zinc is an essential cofactor required for the activity of numerous proteins involved in cellular signaling pathways and biological processes including growth factors, cytokines, receptors, enzymes, and transcription factors [3,4,5,6]. In addition, zinc has been found to play a role in cell-mediated immunity and signal transduction, and as an antioxidant and an anti-inflammatory agent [7,8]. It is broadly acknowledged that numerous disorders are the result of zinc deficiency such as poor appetite, growth retardation, skin lesions, mental lethargy, delayed wound healing, neurosensory disorders, and cell-mediated immune disorders [9,10,11]. Zinc homeostasis in single cells and in whole organism is regulated by two families of zinc transporters: zinc exporters (Slc30a/ZnT or CDF) and importers (Slc39a/ Zip)[10,11,12,13,14,15,16,17]. In addition, the tissue-specific expression of each zinc transporter gene, the metals, hormones and cytokines that influence their expression, and the diseases that have (...truncated)


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Guang Yan, Yuchao Zhang, Junlei Yu, Yu Yu, Fan Zhang, Zhuzhen Zhang, Aimin Wu, Xianghua Yan, Yi Zhou, Fudi Wang. Slc39a7/zip7 Plays a Critical Role in Development and Zinc Homeostasis in Zebrafish, PLOS ONE, 2012, 8, DOI: 10.1371/journal.pone.0042939