Mammalian Polycomb Scmh1 mediates exclusion of Polycomb complexes from the XY body in the pachytene spermatocytes.
The product of the Scmh1 gene, a mammalian homolog of Drosophila Sex comb on midleg, is a constituent of the mammalian Polycomb repressive complexes 1 (Prc1). We have identified Scmh1 as an indispensable component of the Prc1. During progression through pachytene, Scmh1 was shown to be excluded from the XY body at late pachytene, together with other Prc1 components such as Phc1, Phc2, Rnf110 (Pcgf2), Bmi1 and Cbx2. We have identified the role of Scmh1 in mediating the survival of late pachytene spermatocytes. Apoptotic elimination of Scmh1(-/-) spermatocytes is accompanied by the preceding failure of several specific chromatin modifications at the XY body, whereas synapsis of homologous autosomes is not affected. It is therefore suggested that Scmh1 is involved in regulating the sequential changes in chromatin modifications at the XY chromatin domain of the pachytene spermatocytes. Restoration of defects in Scmh1(-/-) spermatocytes by Phc2 mutation indicates that Scmh1 exerts its molecular functions via its interaction with Prc1. Therefore, for the first time, we are able to indicate a functional involvement of Prc1 during the meiotic prophase of male germ cells and a regulatory role of Scmh1 for Prc1, which involves sex chromosomes.
Takada
Yuki
Y
RIKEN Research Center for Allergy and Immunology, 1-7-22 Suehiro, Yokohama, Japan.
Isono
Kyo-ichi
K
Shinga
Jun
J
Turner
James M A
JM
Kitamura
Hiroshi
H
Ohara
Osamu
O
Watanabe
Gen
G
Singh
Prim B
PB
Kamijo
Takehiko
T
Jenuwein
Thomas
T
Burgoyne
Paul S
PS
Koseki
Haruhiko
H
D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D006657:Histones / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism*; D013091:Spermatogenesis / Q000235:genetics / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism; D014960:X Chromosome / Q000378:metabolism; D014998:Y Chromosome / Q000378:metabolism
C570426:Cbx2 protein, mouse; D017931:DNA Primers; D006657:Histones; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; C570430:Scmh1 protein, mouse; D063150:Polycomb Repressive Complex 1