International Mammalian Genome Society

logo18th International Mouse Genome Conference

17-22 October 2004, Seattle, USA


POSTER 78 - DOSAGE COMPENSATION BY UP-REGULATION OF X-LINKED GENES: MICROARRAY REVEALS TISSUE-SPECIFIC DIFFERENCES

Nguyen DK, Disteche C

University of Washington, Seattle, United States

S. Ohno (1967) hypothesized that up-regulation of genes on active Xchromosome would have occurred together with X inactivation to ensure dosage compensation between X chromosome and autosomes and between the sexes.  Using microarrays, we compared the mean expression of X-linked genes against autosomal genes in several tissue types, mammalian species and array types. The dataset that we analyzed was a combination of 587 arrays collected from different laboratories, public databases, arrays platforms and tissues from males and females. Our analysis showed that, overall, the mean expression of X-linked genes is similar to autosomal genes, consistent with up-regulation of the X chromosome in all mammalian species examined, including mouse, rat, human and other primates.  X chromosome up-regulation appeared to be largely independent of tissue type, gender or types of arrays.  However, there was a marked reduction in the expression of X-linked genes in sperm producing testis, consistent with X inactivation spermatogenesis.  Furthermore, the ratio of the mean expression of X-linked genes versus autosomal genes was significantly higher in the brain tissues of mouse, rat, human and primates, which may reflect the large number of brain-specific genes on the X chromosome.  In conclusion, analysis of the overall expression of X-linked genes in comparison to autosomal genes supports Ohno’s hypothesis of X chromosome up-regulation.

[an error occurred while processing this directive]