Cloning And Analysis Of Expression Of A Grass Carp Ctenopharyngodon Idellus QM Homolog CDNA

QM is a human cDNA originally isolated as a transcript elevated in a nontumori-genenic Wilms' tumor microcell hybrid, relative to the tumorigenic parental cell line. It has been cloned from species encompassing members of the plant, animal, and fungal kingdoms. Sequence comparison indicates that QM has been highly conserved throughout eukaryotic evolution. QM is a member of a multigene family in both mouse and man, is expressed in a broad range of tissues, and is downregulated during adipocyte differentiation. Jif-1, a chicken homolog of QM, has been reported to interact with the protooncogene c-Jun, and to inhibit transactivation of AP-1 regulated promoters in vitro. Furthermore, disruption of the yeast QM homolog is lethal. Although these studies suggest that the QM gene product plays an important role within the normal cell, the precise role of QM has remained elusive.In the present work, a gene homologous to QM is isolated from a lambda ZAPII grass carp ( Ctenopharyngodon idellus ) spleen and head kidney cDNA libaray using primers to very conserved regions of the QM gene and to the sequence of the lambda ZAPII vector. It is designated GcQM. The GcQM cDNA measures 751 nucleotides in length and encodes a polypeptide of 215 residues with a corresponding Mr of 24.5 kDa. Analysis of the product of GcQM revealed 96%similarity and 92% identity with QM protein from Homo sapiens and 86% and 76%, respectively, with Drosophila melanogaster.Analysis of GcQM expression in various adult tissues, such as brain, cardiac muscle, head kidney, spleen, liver, muscle, intestines, and is differentially expressed throughout these tissues. In control column, GcQM is strongly expressed in cardiac muscle and brain. However, it is not detectable in other tissues. The GcQM protein can be detected in head kidney and liver when treated with GCHV. While treated with Aeromonas hydrophila, it also can be found in head kidney. This pattern of QM expression suggests that GcQM product may be involved in some immunity function.