title: Functional analysis of the SRY-KRAB interaction in mouse sex determination.
abstract: BACKGROUND
  SRY (sex-determining region Y), the master regulator of male development in mammals, has been studied extensively for more than 17 years, but how the SRY protein triggers the chain of events leading to testis development remains unclear. SRY probably requires a partner protein to elicit its molecular function. KRAB-O, a novel protein containing a KRAB (Krüppel-associated box) domain only, was suggested recently as a candidate SRY partner. In order to investigate the possible role of KRAB-O in sex determination, we studied its expression and conducted functional assays of the SRY-KRAB interaction.
  
  
  RESULTS
  More than 100 KRAB genes were found to be expressed in mouse developing gonads, including 19 transcripts encoded by the KRAB-O cluster that were found to be expressed in somatic cells at 11.5 dpc (days post-coitum). Loss-of-function analysis in Sry-expressing cultured cells, using shRNA (small hairpin RNA) constructs directed against KRAB-O and its homologous genes, resulted in a reduced ability to up-regulate Sox9 [SRY-related HMG (high-mobility group)-box 9]; however, KRAB-knockdown mice exhibited normal testis development.
  
  
  CONCLUSIONS
  Reduced Sox9 expression in KRAB-knockdown cells supports a role for KRAB-O and perhaps other KRAB genes in mediating SRY function. Overlapping expression and potential redundancy between members of the large KRAB-O gene cluster may mask any loss-of-function in vivo, presenting clear challenges for further functional analysis.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Polanco
authors.forename: Dagmar
authors.initials: D
authors.lastname: Wilhelm
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Mizusaki
authors.forename: Andrew
authors.initials: A
authors.lastname: Jackson
authors.forename: Catherine
authors.initials: C
authors.lastname: Browne
authors.forename: Tara
authors.initials: T
authors.lastname: Davidson
authors.forename: Vincent
authors.initials: V
authors.lastname: Harley
authors.forename: Andrew
authors.initials: A
authors.lastname: Sinclair
authors.forename: Peter
authors.initials: P
authors.lastname: Koopman
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D011485:Protein Binding / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D055758:SOX9 Transcription Factor / Q000235:genetics*; D019849:Sex Determination Processes; D051876:Sex-Determining Region Y Protein / Q000378:metabolism* / Q000502:physiology; D013737:Testis / Q000254:growth & development; D015854:Up-Regulation / Q000235:genetics
chemical_list: D002352:Carrier Proteins; C534242:KRAB-O protein, mouse; D034741:RNA, Small Interfering; D055758:SOX9 Transcription Factor; D051876:Sex-Determining Region Y Protein; C527933:Sox9 protein, mouse; C497746:Sry protein, mouse