title: Temporal and spatial expression of the four Igf ligands and two Igf type 1 receptors in zebrafish during early embryonic development.
abstract: The insulin-like growth factor (Igf) family is an evolutionarily conserved system essential for normal growth and development in vertebrates. Unlike mammals, four distinct Igf ligands (Igf1, Igf2a, Igf2b and Igf3) and two Igf type 1 receptors (Igf1ra and Igf1rb) are present in zebrafish. However, the localization of these multiple ligands and receptors especially the recently discovered igf3 during early development of zebrafish is poorly understood. In this study, detailed expression patterns of these components of the Igf system during embryogenesis of zebrafish were analyzed. It was found that igf1 is specifically expressed in the trigeminal ganglia region from 18 hpf to 72 hpf, while igf2a is restricted to the caudal regions of the notochord from 14 hpf to 18 hpf as well as in the midbrain, dorsal hind brain and otic vesicle at 24 hpf. On the other hand, igf2a is highly expressed in the midbrain and pharyngeal arch region at 48 hpf, followed by its appearance in the liver and brain at 72 hpf, while igf2b is restricted to the floor plate and hypochord from 12 hpf to 18 hpf, and strong expression is also detected in the midbrain and dorsal hind brain at 24 hpf. The teleost specific igf3 is highly expressed in the pharyngeal arch region before 24 hpf, but is then restricted to the sternohyoideus after 48 hpf. The receptor subtype igf1ra is ubiquitously expressed before 24 hpf but is confined to the brain at 72 hpf. However, igf1rb is widely expressed before 10 hpf, but is more confined to the brain region at 24 hpf and 72 hpf. This dynamic temporal-spatial expression during embryogenesis of zebrafish, together with the unique and overlapping expression patterns of the Igf ligands and receptors suggest the coordination of the divergent functions of the Igf system during early development in zebrafish.
authors.affiliation: College of Life Sciences, Northwest Normal University, Lanzhou, China.
authors.forename: Jianzhen
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.affiliation: School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing, China.
authors.forename: Deshou
authors.initials: D
authors.lastname: Wang
authors.affiliation: School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China. Electronic address: chkcheng@cuhk.edu.hk.
authors.forename: Christopher H K
authors.initials: CH
authors.lastname: Cheng
mesh_terms: D000818:Animals; D001483:Base Sequence; D047108:Embryonic Development / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D008024:Ligands; D008969:Molecular Sequence Data; D060888:Real-Time Polymerase Chain Reaction; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D013002:Somatomedins / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C000596542:Igf2a protein, zebrafish; C000596543:Igf2b protein, zebrafish; D008024:Ligands; D013002:Somatomedins; D029961:Zebrafish Proteins; C431139:igf1 protein, zebrafish; C558670:insulin-like growth factor 3, zebrafish; D017526:Receptor, IGF Type 1
keywords: Embryo; Gene expression; Igf; Igf1r; Zebrafish