title: CeRh1 (rhr-1) is a dominant Rhesus gene essential for embryonic development and hypodermal function in Caenorhabditis elegans.
abstract: Rhesus (Rh) proteins share a conserved 12-transmembrane topology and specify a family of putative CO(2) channels found in diverse species from microbes to human, but their functional essentiality and physiological importance in metazoans is unknown. To address this key issue and analyze Rh-engaged physiologic processes, we sought to explore model organisms with fewer Rh genes yet are tractable to genetic manipulations. In this article, we describe the identification in nematodes of two Rh homologues that are highly conserved and similar to human Rh glycoproteins, and we focus on their characterization in Caenorhabditis elegans. RNA analysis revealed that CeRh1 is abundantly expressed in all developmental stages, with highest levels in adults, whereas CeRh2 shows a differential and much lower expression pattern. In transient expression in human cells, both CeRh1 and CeRh2-GFP fusion proteins were routed to the plasma membrane. Transgenic analysis with GFP or LacZ-fusion reporters showed that CeRh1 is mainly expressed in hypodermal tissue, although it is also in other cell types. Mutagenesis analysis using deletion constructs mapped a minimal promoter region driving CeRh1 gene expression. Although CeRh2 was dispensable, RNA interference with CeRh1 caused a lethal phenotype mainly affecting late stages of C. elegans embryonic development, which could be rescued by the CbRh1 homologue from the worm Caenorhabditis briggsae. Taken together, our data provide direct evidence for the essentiality of the CeRh1 gene in C. elegans, establishing a useful animal model for investigating CO(2) channel function by cross-species complementation.
authors.affiliation: Laboratory of Biochemistry and Molecular Genetics, Lindsley F. Kimball Research Institute, New York Blood Center, 310 East 67th Street, New York, NY 10021, USA.
authors.forename: Qiongmei
authors.initials: Q
authors.lastname: Ji
authors.forename: Sarwar
authors.initials: S
authors.lastname: Hashmi
authors.forename: Zhi
authors.initials: Z
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Cheng-Han
authors.initials: CH
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics*; D017124:Conserved Sequence; D004625:Embryo, Nonmammalian / Q000502:physiology*; D047108:Embryonic Development / Q000235:genetics; D005799:Genes, Dominant; D006801:Humans; D008969:Molecular Sequence Data; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029742:Caenorhabditis elegans Proteins; D012204:Rh-Hr Blood-Group System