Group 1 CD1 Genes in Rabbit

Abstract

CD1 is an Ag-presenting molecule that can present lipids and glycolipids to T cells. The CD1 genes were first identified in the human, and since then, homologs have been identified in every mammalian species examined to date. Over a decade ago, CD1B and CD1D homologs were identified in the rabbit. We have extended this earlier study by identifying additional CD1 genes with the goal of developing the rabbit as an animal model to study the function of CD1 proteins. We constructed a thymocyte cDNA library and screened the library with CD1-specific probes. Based on nucleotide sequence analyses of the CD1+ cDNA clones obtained from the library, we have identified two CD1A genes and one CD1E gene as well as determined the complete sequence of the previously identified CD1B gene. The CD1E+ cDNA clones lacked the transmembrane and cytoplasmic domains and, if translated, would encode for a soluble or secreted CD1E protein. In addition, expression studies demonstrated that the CD1 genes were expressed in peripheral lymphoid tissues as well as in skin, gut, and lung. Of interest is the finding that CD1A2, CD1B, and CD1E genes were found to be expressed by rabbit B cell populations. The rabbit, with a complex CD1 locus composed of at least two CD1A genes, one CD1B gene, one CD1D gene, and one CD1E gene, is an excellent candidate as an animal model to study CD1 proteins.

Chicken CD1 genes are located in the MHC: CD1 and endothelial protein C receptor genes constitute a distinct subfamily of class-I-like genes that predates the emergence of mammals

“…In man, CD1a, CD1b, CD1c, and possibly CD1e are group 1 molecules, and CD1d is a member of the group 2 CD1 molecules. Mice and rats have only group 2 CD1 molecules (Balk et al 1991;Ichimiya et al 1994), but rabbit and sheep have both groups of CD1 molecules (Calabi et al 1989a;Dascher et al 1999;Hayes and Knight 2001), indicating that group 1 CD1 genes were lost in a rodent lineage (Dascher and Brenner 2003). Phylogenetic analysis indicates that chicken CD1.1 and CD1.2 are neither group 1-nor group 2-like and that the duplication event that gave rise to chicken CD1.1 and CD1.2 took place independently from the one that created the two groups of mammalian CD1 genes (Fig.…”

CD1-Restricted T Cells in Host Defense to Infectious Diseases

“…The expression of CD1b in leprosy lesions was confirmed in a study that linked this to the development of increased local immunity to M. leprae, and suggested that toll-like receptor signaling could induce monocytes to differentiate into these group 1 CD1 + dendritic cells [16]. Recent progress in defining group 1 CD1 molecules in a variety of other mammalian species, such as guinea pigs [9,17,18], rabbits [19], cows [20], and nonhuman primates [21], may allow the development of more advanced studies on the modulation of group 1 CD1 molecules by infection in vivo.…”

Mammalian CD1 and MR1 genes

“…Genomes from these nine mammalian species contain from one (rat (Katabami et al 1998)) to thirteen (horse and dog (Dossa et al 2014; Schjaerff et al 2016)) CD1 genes. From rabbits, two CD1a, two CD1b, one CD1d, and one CD1e transcripts have been identified, but this study was not set up or intended to define the complete rabbit CD1 locus (Hayes and Knight 2001). Southern blots suggested the presence of at least eight CD1 genes in the rabbit (Calabi et al 1989).…”

“…However, only two of the three studied canine CD1a genes (out of the nine CD1a genes in the dog CD1 locus) were preferentially expressed in the skin. In rabbits, one of the two CD1a genes is preferentially expressed in the skin, while the other one has a more general expression pattern (Hayes and Knight 2001). In guinea pigs, different CD1b genes have different expression patterns in peripheral blood and spleen (Hiromatsu et al 2002).…”