A novel X gene with a widely transcribed Y-linked homologue escapes X-inactivation in mouse and human

• Published in: Human molecular genetics Vol. 3; no. 6; p. 879
• Main Authors: Agulnik, A I, Mitchell, M J, Mattei, M G, Borsani, G, Avner, P A, Lerner, J L, Bishop, C E
• Format: Journal Article
• Language: English
• Published: England 01-06-1994
• Subjects: Alleles; Animals; Base Sequence; Chromosome Mapping; Cloning, Molecular; DNA Primers; DNA, Complementary - analysis; Female; Hominidae - genetics; Humans; In Situ Hybridization; Male; Meiosis; Mice - genetics; Molecular Sequence Data; Polymerase Chain Reaction; Sequence Homology, Nucleic Acid; X Chromosome; Y Chromosome
• ISSN: 0964-6906
• DOI: 10.1093/hmg/3.6.879

A new gene, designated Smcx, was cloned from the mouse X chromosome by its homology to the Y located gene Smcy. Using direct in situ hybridisation Smcx was mapped to the distal end of the mouse X chromosome (XF2-XF4) and its human homologue, SMCX, was mapped to proximal Xp (Xp11.1-Xp11.2). Further meiotic mapping in the mouse placed Smcx in the Plp-Pdha1 interval. As Smcx/SMCX have widely expressed homologues on the Y chromosome, they appeared good candidates for genes that escape X-inactivation. In the human we show this to be the case as SMCX is expressed in hamster-human hybrids containing either an active or inactive human X chromosome. Two alleles of Smcx were found to be expressed in T(16;X)16H female mice despite the intact X chromosome being inactive in all cells. This indicates that Smcx is also not subject to X-inactivation and provides the first example of a gene that is expressed from inactive and active X chromosomes in the mouse.