Molecular characterization and tissue-specific expression of invariant chain in the muscovy duck (Cairina moschata)

Abstract

ABSTRACT. The invariant chain (Ii) plays an important role as a chaperone for MHC II maturation and facilitates antigen presentation in vertebrates. We cloned, characterized and made a homology analysis of healthy adult muscovy duck Ii (MDIi), from a poultry farm in the suburban district of Hefei city in China, by rapid amplification of cDNA ends (RACE)-PCR and by measuring expression of the MDIi gene in various tissues by real-time quantitative PCR. A full-length cDNA sequence of MDIi was obtained, 1188-bp long, encoding a 222-amino acid protein. A comparison of the amino acid sequence of Ii between muscovy duck and other birds showed high similarity (66.3-95.3%). Characteristic functional domains found in Ii of other species, such as cytoplasmic domain, transmembrane domain, class ІІ-associated Ii-derived peptide (CLIP) and trimerization domain, were identified in MDIi. Although all functional domains of Ii were found to be highly conserved, small differences in the CLIP sequence occur among the various species. Expression of MDIi was detected in all tissues at different levels. A higher expression level was found in the spleen, intestinal mucosa and the bursa stipe (bursa of Fabricius stipe)

Molecular characterization and tissue-specific expression of invariant chain isoform in Muscovy Duck (Cairina moschata)

“…MDIi-2 expression was detected in various tissues, but expression levels were tissue-specific (Figure 4), similar to the expression pattern observed for MDIi-1 (Liu et al, 2011). MDIi-2 expression in the bursa fundus was the lowest of all tissues tested; thus, this level was selected as the calibrator.…”

“…Ducks were purchased from a poultry farm in the suburban district of Hefei City, China. The methods used to extract total RNA from tissues and those for single-stranded cDNA synthesis from 5 μg RNA have been reported previously (Liu et al, 2011).…”

“…p41 also consistently contains conserved Tg domains, which are remarkably similar each other on the amino acid sequence level and in their molecular structures in various species (Zhong et al, 2006;Chen et al, 2013). Ii in Muscovy Duck (MDIi) might contains these 2 isoforms, MDIi-1 [MDIi in reference (Liu et al, 2011), GenBank accession No. HQ909102; KF584915.1 referred to as MDIi-1 for convenience], which has been cloned previously, and MDIi-2.…”

“…GU564232). Real-time RQ-PCR amplification of MDIi-2 was carried; MDIi-1 was also amplified as reported in reference previous study (Liu et al, 2011), using the same methods and cDNA from 12 tissues, under the same conditions, on the same instruments. The lowest value of expression level of MDIi-2 in the tissue was used as calibrator.…”

“…The methods used for bioinformatic analysis and homology modeling have been reported previously (Liu et al, 2011). Briefly, the cDNA sequences of MDIi-2 were analyzed using DNASTAR 5.0 (DNASTAR Inc., Madison, WI, USA).…”