GENOMIC ORGANIZATION OF A CDNA (QM) DEMONSTRATING AN ALTERED MESSENGER-RNA LEVEL IN NONTUMORIGENIC WILMS MICROCELL HYBRID-CELLS AND ITS LOCALIZATION TO XQ28

Using a cosmid clone derived from human Xq28 as a probe which shows cross-species homology, we isolated cDNA clones and the nucleotide sequence analysis of the cDNA revealed that the cDNA is identical to QM cDNA. The QM cDNA has recently been reported as a cDNA with down-regulation in tumorigenic Wilms' tumor microcell hybrid. Comparison of the nucleotide sequences of the cDNA with those of the genomic DNA allowed us to determine the genomic organization of the QM gene. The QM gene consists of at least 7 exons and is located at Xq28. Southern blot analysis of a somatic cell hybrid panel indicates that the QM genes are scattered at least to chromosome 2, 3, 6, 14, 16, and possibly to other chromosomes. Northern blot analysis demonstrated the QM gene is expressed in ali the examined adult human tissues as well as cell lines including HeLa cells, fibroblasts, and somatic cell hybrids with increased expression in liver, spleen, testis, and adrenal gland. The results suggest that the QM gene belongs to a new multi-gene family with yet undetermined function.