Origin and evolution of the Cat Eye Syndrome critical region in human chromosome 22q11.
Shunnosuke Abe, Yusuke Kobayashi (Faculty of Agriculture, Ehime University)
In the previous work, we demonstrated that human 3p25 synteny containing SYN2, PPARG, MKRN2, and RAF1 was created during evolution of fish, and genomic duplications created four paralogous syntenic copies in human chromosome regions 6p21, 7q31-7q34, 22q12-13, and Xp11.
In the present study, we further analyzed flanking genes of 3p25 syntenic members identified in the Torafugu genomic database and determined their expression with cDNA isolated from ovary and liver. CECR5 was found in the upstream of RAF1 and CECR6 downstream of MKRN1 in Torafugu genomic scaffolds. In addition, the last exon of IL17R was located downstream of CECR6 on the opposite strand, in the same configuration as seen in human chromosome 22q11, with a high degree of conservation in sequence similarity and exon/intron structures. These results supported that the major part of the long arm of human chromosome 22 (q11 to q13), with a collinear order of IL17R, CECR6, and CECR5 (22q11) and SYN3 (22q12) and PPARA (22q13), is homologous to the ancestral 3p25 synteny containing a similar paralogous set of reference genes (SYN, PPAR, MKRN, RAF, CECR5, CECR6, and IL17R). It is also noted that CECR5, CECR6, and IL17R were likely to be functional in fish because their cDNAs were obtained from liver or ovary in Torafugu.
Annual meetings of Japanese Society of Agricultural Biological Chemistry (Chu-Shikoku Branch) at Tokushima University, 2004 Sept 18. Sesion D, number 6 (Abstracts p19)