The Drosophila developmental gene fat facets has a human homologue in Xp11.4 which escapes X-inactivation and has related sequences on Yq11.2 [published erratum appears in Hum Mol Genet 1997 Feb;6(2):334-5]

Abstract

EST 221 derived from human adult testis detects homology to the Drosophila fat facets gene (fat) and has related sequences on both the X and Y chromosomes mapping to Xp11.4 and Yq11.2 respectively. These two loci have been termed DFFRX and DFFRY for Drosophila fat facets related X and Y. The major transcript detected by EST 221 is-8 kb in size and is expressed widely in a range of 16 human adult tissues. RT-PCR analysis of 13 different human embryonic tissues with primers specific for the X and Y sequences demonstrates that both loci are expressed in developing tissues and quantitative RT-PCR of lymphoblastoid cell lines carrying different numbers of X chromosomes reveals that the X-linked gene escapes X-inactivation. The amino acid sequence (2547 residues) of the complete open reading frame of the X gene has 44% identity and 88% similarity to the Drosophila sequence and contains the conserved Cys and His domains characteristic of deubiquitinating enzymes, suggesting its biochemical function may be the hydrolysis of ubiquitin from protein-ubiquitin conjugates. The requirement of faf for normal oocyte development in Drosophila combined with the map location and escape from X-inactivation of DFFRX raises the possibility that the human homologue plays a role in the defects of oocyte proliferation and subsequent gonadal degeneration found in Turner syndrome.

Identification of Ubiquitin-specific Protease 9X (USP9X) as a Deubiquitinase Acting on Ubiquitin-Peroxin 5 (PEX5) Thioester Conjugate

“…USP9X is a 290-kDa DUB encoded in the X chromosome of humans, mice, and rats (58 -60). We note that some of the peptides matching USP9X might also be derived from USP9Y (see footnote in supplemental Table S2), a DUB homologous to USP9X but encoded in the Y chromosome (58,61). Although the presence of USP9Y in rat liver is presently doubtful (USP9Y, in contrast to USP9X, is not expressed in mouse liver; see Ref.…”

A novel expression based approach for assessing the inactivation status of human X-linked genes

“…17 It is therefore of interest that two other genes from the same cytogenetic location have recently been shown to escape inactivation. 18,19 Unfortunately, these loci still await fine mapping to demonstrate if they are clustered or interspersed among normally inactivated genes. A similar approach to the one we describe, exploiting well characterised differences between laboratory strains, has been used in the mouse to demonstrate the inactivation of the Rps4, Zfx and Ubel genes.…”

A close correlation in the expression patterns of Af-6 and Usp9x in Sertoli and granulosa cells of mouse testis and ovary

“…Drosophila fat facet ( faf) gene, which encodes an ubiquitin-specific protease, has been shown to be important in oocyte development and eye formation (Fischer-Vize et al 1992, Huang et al 1995, Cadavid et al 2000. In mice and humans, two faf homologous genes with a high sequence similarity have been isolated on sex chromosomes: X-linked Usp9x (also known as Fam or Dffrx) (Jones et al 1996, Wood et al 1997, Brown et al 1998) and Y-linked Usp9y (also known as Dffry) (Jones et al 1996, Hall et al 2003. Mouse Usp9y is a testis-specific gene, which is probably expressed in spermatogenic cell lineage (Jones et al 1996).…”

“…In mice and humans, two faf homologous genes with a high sequence similarity have been isolated on sex chromosomes: X-linked Usp9x (also known as Fam or Dffrx) (Jones et al 1996, Wood et al 1997, Brown et al 1998) and Y-linked Usp9y (also known as Dffry) (Jones et al 1996, Hall et al 2003. Mouse Usp9y is a testis-specific gene, which is probably expressed in spermatogenic cell lineage (Jones et al 1996). A de novo point mutation in human USP9Y has been identified in an azoospermic man (Sun et al 1999), suggesting its essential role in spermatogenesis.…”

“…A de novo point mutation in human USP9Y has been identified in an azoospermic man (Sun et al 1999), suggesting its essential role in spermatogenesis. Human USP9X was originally isolated as a possible candidate gene for the defects of oocyte proliferation and subsequent gonadal degeneration found in Turner syndrome (Jones et al 1996). In mice, Usp9x expression shows a stage-specific pattern in supporting cells (i.e.…”