Identification of mediator complex 26 (Crsp7) gametologs on platypus X1 and Y5 sex chromosomes: a candidate testis-determining gene in monotremes?
The basal lineage of monotremes features an extraordinarily complex sex chromosome system which has provided novel insights into the evolution of mammalian sex chromosomes. Recently, sequence information from autosomes, X chromosomes, and XY-shared pseudoautosomal regions has become available. However, no gene has so far been described on any of the Y chromosome-specific regions. We analyzed sequences derived from Y-specific BAC clones to identify genes with potentially male-specific function. Here, we report the identification and characterization of the mediator complex protein gametologs on platypus Y5 (Crspy). We also identified the X-chromosomal copy which unexpectedly maps to X1 (Crspx). Sequence comparison shows extensive divergence between the X and Y copy, but we found no significant positive selection on either gametolog. Expression analysis shows widespread expression of Crspx. Crspy is expressed exclusively in males with particularly strong expression in testis and kidney. Reporter gene assays to investigate whether Crspx/y can act on the recently discovered mouse Sox9 testis-specific enhancer element did reveal a modest effect together with mouse Sox9 + Sf1, but showed overall no significant upregulation of the reporter gene. This is the first report of a differentiated functional male-specific gene on platypus Y chromosomes, providing new insights into sex chromosome evolution and a candidate gene for male-specific function in monotremes.
The Robinson Institute, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia.
Enkhjargal
E
Tsend-Ayush
R Daniel
RD
Kortschak
Pascal
P
Bernard
Shu Ly
SL
Lim
Janelle
J
Ryan
Ruben
R
Rosenkranz
Tatiana
T
Borodina
Juliane C
JC
Dohm
Heinz
H
Himmelbauer
Vincent R
VR
Harley
Frank
F
Grützner
D000818:Animals; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D033481:Chromosomes, Mammalian / Q000235:genetics; D019143:Evolution, Molecular; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D024282:Genes, sry; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008297:Male; D056892:Mediator Complex / Q000235:genetics*; D051379:Mice; D010802:Phylogeny; D020161:Physical Chromosome Mapping; D010987:Platypus / Q000235:genetics*; D055758:SOX9 Transcription Factor / Q000235:genetics; D019849:Sex Determination Processes; D013737:Testis / Q000166:cytology / Q000502:physiology*; D014162:Transfection; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000235:genetics*
D056892:Mediator Complex; D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse