A Novel High Mobility Group Protein Gene Is a Candidate for Xp22 Abnormalities in Uterine Leiomyomas and Other Benign Tumors

Because genes of the high mobility group protein family HMGI(Y) are known to take part in the development of a variety of benign solid tumors, the aim of the present study was to search for further members of that family in the human genome. Analysis for HMGI(Y)-related sequences by the polymerase chain reaction (PCR) with the use of cDNA-specific primers offered evidence for HMGIY-like sequences, whereas HMGIC-related sequences were apparently absent. By chromosomal assignment of somatic cell hybrids PCR, HMGIY cDNA-related sequences were detected on seven chromosomes. Positive clones were obtained by screening of a P1-derived artificial chromosome library and mapped by fluorescence in situ hybridization. One of these clones assigned to Xp22.1 was chosen for further analysis because Xp22 is a target region for clonal aberrations in benign solid tumors. Sequence analysis of a DNA fragment of this clone, designated as HMGIYL1, revealed a 94.4% homology to the coding region of HMGIY. Within the HMGIYL1 sequence, no nucleotide sequence divergences leading to a frame shift or a new termination codon compared to HMGIY were found, and a TATA-box-like motif 5′ of it was detected. By reverse transcriptase PCR experiments with the use of HeLa cells and human fetal tissue, HMGIYL1 expression was not detectable. Nevertheless, if not active by itself, it is possible that HMGIYL1 may become activated by chromosomal rearrangements of Xp22 observed in benign solid tumors.