Duplicated ssat1 genes, as is the case in medaka, stickleback, takifugu

Duplicated ssat1 genes, as is the case in medaka, stickleback, takifugu, and tetraodon. Thus there is only one ssat1 left in these species. However, zebrafish, which contains not one but three ssat1 homologues, is an exception. The phylogeneticanalysis indicates that all get JWH133 zebrafish ssat1 homologues are derived from a common ancestor (Fig. 1). The remnants of vertebrates’ ssat1 syntenic genes are found scattering in the loci of each homologue. For example, acot9 and apoo are clustered with ssat1a in chromosome 24, and prdx4 is closely located near ssat1b and ssat1c in chromosome 5 (Fig. S1). It is worth to note that the sequences between ssat1b and ssat1c are more similar to each other (Fig. S2). Further, Ssat1b and Ssat1c also have similar translational regulation pattern and protein-protein interaction relationships with Hif-1a and Integrin a9. These observations suggest that ssat1a might be one of the products from the teleosts’ whole genome duplication while the other one underwent a local duplication to form ssat1b and ssat1c later on. Our results suggest that zebrafish ssat1 homologues are paralogous genes which experienced subfunctionalization in their function and regulation. It is worth noting that only Ssat1b and Ssat1c, but not the polyamine-insensitive Ssat1a, are able to interact with integrin a9 and Hif-1a. Thus these signal pathways could be regulated by Ssat1 in response to cellular polyamine level. Mirin web Besides polyamine catabolism, it might be the key feature that allows Ssat1 to coordinate certain physiological responses in vertebrates, such as fine-tuning the advanced immune system and the homeostasis of polyamine and hypoxia. By characterizing properties of zebrafish family of Ssat1 proteins and the artificial chimeric enzymes, our data revealed some correlations between their sequences and functions that may provide valuable information for studies of the translational regulatory mechanism, protein stability, and physiological functions of Ssat1 in the future.Supporting InformationFigure S1 Chromosomal localizations of human SSAT1 and zebrafish ssat1 homologues. (TIF) Figure S2 Alignment of zebrafish ssat1 homologues cDNA sequence. The cDNA sequences were aligned by MegAlign (Lasergene) with the ClustalW method. The conserved residues are shaded black. The denoted amino acid sequences underneath cDNA sequences are consensus residues in all three homologues, while the encoded amino acids which are not conserved in all three homologues are denoted by dash symbols. (TIF)Translational regulation of ssat1 genes in zebrafish cells. ZF4 cells were transiently transfected with the plasmid encoding myc-tagged full-length human SSAT1, zebrafish Ssat1a, or Ssat1b. After incubation for 12 h, transfected cells were treated with 10 mM DENSPM, 20 mM MG132, or vehicle for 24 h. Cell lysates (5 mg total protein in each lane) were prepared and the Ssat1 protein content in each sample was detected by western blotting with anti-myc antibody. (TIF)Figure S3 Figure S4 Sequence alignment of integrin a9. The amino acid sequences of human (NP_002198), mouse (NP_598482), and zebrafish integrin a9 (XP_003199805) were aligned by MegAlign (Lasergene) with the ClustalW method. The conserved residues are shaded in black. The cytosolic domains are marked with a red box. (TIF) Figure S5 Sequence alignment of human, mouse and zebrafish Hif-1a. The amino acid sequences of human (NP_001521), mouse (NP_034561), and zebrafish Hif-1a (AAQ91619) were aligned b.Duplicated ssat1 genes, as is the case in medaka, stickleback, takifugu, and tetraodon. Thus there is only one ssat1 left in these species. However, zebrafish, which contains not one but three ssat1 homologues, is an exception. The phylogeneticanalysis indicates that all zebrafish ssat1 homologues are derived from a common ancestor (Fig. 1). The remnants of vertebrates’ ssat1 syntenic genes are found scattering in the loci of each homologue. For example, acot9 and apoo are clustered with ssat1a in chromosome 24, and prdx4 is closely located near ssat1b and ssat1c in chromosome 5 (Fig. S1). It is worth to note that the sequences between ssat1b and ssat1c are more similar to each other (Fig. S2). Further, Ssat1b and Ssat1c also have similar translational regulation pattern and protein-protein interaction relationships with Hif-1a and Integrin a9. These observations suggest that ssat1a might be one of the products from the teleosts’ whole genome duplication while the other one underwent a local duplication to form ssat1b and ssat1c later on. Our results suggest that zebrafish ssat1 homologues are paralogous genes which experienced subfunctionalization in their function and regulation. It is worth noting that only Ssat1b and Ssat1c, but not the polyamine-insensitive Ssat1a, are able to interact with integrin a9 and Hif-1a. Thus these signal pathways could be regulated by Ssat1 in response to cellular polyamine level. Besides polyamine catabolism, it might be the key feature that allows Ssat1 to coordinate certain physiological responses in vertebrates, such as fine-tuning the advanced immune system and the homeostasis of polyamine and hypoxia. By characterizing properties of zebrafish family of Ssat1 proteins and the artificial chimeric enzymes, our data revealed some correlations between their sequences and functions that may provide valuable information for studies of the translational regulatory mechanism, protein stability, and physiological functions of Ssat1 in the future.Supporting InformationFigure S1 Chromosomal localizations of human SSAT1 and zebrafish ssat1 homologues. (TIF) Figure S2 Alignment of zebrafish ssat1 homologues cDNA sequence. The cDNA sequences were aligned by MegAlign (Lasergene) with the ClustalW method. The conserved residues are shaded black. The denoted amino acid sequences underneath cDNA sequences are consensus residues in all three homologues, while the encoded amino acids which are not conserved in all three homologues are denoted by dash symbols. (TIF)Translational regulation of ssat1 genes in zebrafish cells. ZF4 cells were transiently transfected with the plasmid encoding myc-tagged full-length human SSAT1, zebrafish Ssat1a, or Ssat1b. After incubation for 12 h, transfected cells were treated with 10 mM DENSPM, 20 mM MG132, or vehicle for 24 h. Cell lysates (5 mg total protein in each lane) were prepared and the Ssat1 protein content in each sample was detected by western blotting with anti-myc antibody. (TIF)Figure S3 Figure S4 Sequence alignment of integrin a9. The amino acid sequences of human (NP_002198), mouse (NP_598482), and zebrafish integrin a9 (XP_003199805) were aligned by MegAlign (Lasergene) with the ClustalW method. The conserved residues are shaded in black. The cytosolic domains are marked with a red box. (TIF) Figure S5 Sequence alignment of human, mouse and zebrafish Hif-1a. The amino acid sequences of human (NP_001521), mouse (NP_034561), and zebrafish Hif-1a (AAQ91619) were aligned b.