High impact information on Rhox9

• Normal gonadal development in mice lacking GPBOX, a homeobox protein expressed in germ cells at the onset of sexual dimorphism [1].
• Gpbox is a paired-like homeobox gene that colocalizes with two other members of the family, PsxI and Pem, on the proximal portion of the mouse X chromosome [1].
• To investigate the function of Gpbox, mouse cell lines lacking GPBOX were established using targeted mutagenesis in embryonic stem cells [1].
• Gpbox is expressed in the extraembryonic placenta and within the germ cells of the embryonic gonad [1].
• The lack of an obvious phenotype raises the possibility that another member of this homeobox gene family provides the absent Gpbox function [1].

Biological context of Rhox9

• Few cDNAs were specifically expressed in the urogenital ridge, but one, designated GPBOX, encodes a 227-amino-acid homeobox protein that is first expressed at E10.5 in the embryo as well as in the extraembryonic tissues [2].
• The Gpbox gene is single copy in the mouse genome and is located on the X chromosome in close proximity to two other homeobox genes, Pem and Psx1 [2].
• The persistence of GPBOX transcripts in female germ cells until E15.5 and their virtual disappearance in males by E13.5 suggest that Gpbox may play a role in mammalian oogenesis [2].
• Beginning with the onset of sexual dimorphism (embryonic day [E]11.5 to 12.5), GPBOX transcripts accumulate faster in female than in male germ cells but disappear later in embryogenesis (E16) and have not been reported in adult tissues [1].

Anatomical context of Rhox9

• Although comparable levels are initially present in both sexes, GPBOX transcripts accumulate faster in female germ cells and peak at E12.5 when they are present in fivefold greater abundance than in males [2].

Associations of Rhox9 with chemical compounds

• Further, the amino acid at position 51, which is invariably an asparagine in other homeodomains and is known to contact DNA directly, is a methionine in the homeodomains of both Psx-1 and Psx-2 [3].

References