The Non-random Location of Autosomal Genes that Participate in X Inactivation

ABSTRACTBy transcribing XIST RNA, the human inactive X chromosome has a prime role in X-dosage compensation. Yet, the autosomes also play an important role in the process. In fact, multiple genes on human chromosome 1 interact with XIST RNA to silence the inactive Xs, no matter how many there are. And it is likely that multiple genes on human chromosome 19 prevent the silencing of the single active X, which is a highly dosage sensitive process. Previous studies of the organization of chromosomes in the nucleus and their genomic interactions indicate that most contacts are intra-chromosomal. Coordinate transcription or dosage regulation could explain the clustered organization of these autosomal genes on these two chromosomes that are critical for X dosage compensation in human cells. Unlike those on chromosome 1, the genes within the critical eight MB region of chromosome 19, have remained together in all mammals assayed, except rodents, indicating that their proximity in non-rodent mammals is evolutionarily conserved.