Bimodal evolution of the killer cell Ig-like receptor (KIR) family in New World primates
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ORIGINAL PAPER
Bimodal evolution of the killer cell Ig-like receptor (KIR) family in New World primates Luis F. Cadavid & Catalina Palacios & Juan S. Lugo
Received: 26 April 2013 / Accepted: 26 June 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract The immunoglobulin-like receptor (KIR) gene family in New World primates (Platyrrhini) has been characterized only in the owl monkey (Aotus sp.). To gain a better understanding of the KIR system in Platyrrhini, we analyzed a KIR haplotype in Ateles geoffroyi, and sequenced KIR complementary DNAs (cDNAs) from other three Atelidae species, Ateles hybridus, Ateles belzebuth, and Lagothrix lagotricha. Atelidae expressed a variable set of activating and inhibitory KIRs that diversified independently from their Catarrhini counterparts. They had a unique mechanism to generate activating receptors from inhibitory ones, involving a single nucleotide deletion in exon 7 and a change in the donor splice site of intron 7. The A. geoffroyi haplotype contained at least six gene models including a pseudogene, two coding inhibitory receptors, and three coding activating receptors. The centromeric region was in a tail-to-tail orientation with respect to the telomeric region. The owl monkey KIR haplotype shared this organization, and in phylogenetic trees, the centromeric genes clustered together with those of A. geoffroyi, whereas their telomeric genes clustered independently. KIR cDNAs from the other Atelidae species conformed to
Nucleotide sequence data reported are available in the GenBank database under accession numbers KF011940-KF011974. Electronic supplementary material The online version of this article (doi:10.1007/s00251-013-0719-4) contains supplementary material, which is available to authorized users. L. F. Cadavid (*) : C. Palacios : J. S. Lugo Department of Biology and Institute of Genetics, Universidad Nacional de Colombia, Cr. 30 no. 45-08, Bogotá, Colombia e-mail: [email protected] Present Address: C. Palacios Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia
this pattern. Signatures of positive selection were found in residues predicted to interact with the major histocompatibility complex. Such signatures, however, primarily explained variability between paralogous genes but not between alleles in a locus. Atelidae, therefore, has expanded the KIR family in a bimodal fashion, where an inverted centromeric region has remained relatively conserved and the telomeric region has diversified by a rapid process of gene duplication and divergence, likely favored by positive selection for ligand binding. Keywords KIR . Killer cell Ig-like receptor . New World primates . Atelidae
Introduction Natural killer (NK) cells are granular lymphocytes with cytotoxic effects against virus-infected, allogeneic, and transformed cells (Moretta et al. 2003). Their function is largely controlled by a variable set of activating and inhibitory receptors specific for major histocompatibility complex (MHC) class I molecules (McQueen and Parham 2002). An
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