TY - JOUR
T1 - Ubiquitin ligase Rad18Sc localizes to the XY body and to other chromosomal regions that are unpaired and transcriptionally silenced during male meiotic prophase
AU - van der Laan, Roald
AU - Uringa, Evert Jan
AU - Wassenaar, Evelyne
AU - Hoogerbrugge, Jos W.
AU - Sleddens, Esther
AU - Odijk, Hanny
AU - Roest, Henk P.
AU - de Boer, Peter
AU - Hoeijmakers, Jan H.J.
AU - Grootegoed, J. Anton
AU - Baarends, Willy M.
PY - 2004/10/1
Y1 - 2004/10/1
N2 - In replicative damage bypass (RDB) in yeast, the ubiquitin-conjugating enzyme RAD6 interacts with the ubiquitin ligase RAD18. In the mouse, these enzymes are represented by two homologs of RAD6, HR6a and HR6b, and one homolog of RAD18, Rad18Sc. Expression of these genes and the encoded proteins is ubiquitous, but there is relatively high expression in the testis. We have studied the subcellular localization by immunostaining Rad18Sc and other RDB proteins in mouse primary spermatocytes passing through meiotic prophase in spermatogenesis. The highest Rad18Sc protein level is found at pachytene and diplotene, and the protein localizes mainly to the XY body, a subnuclear region that contains the transcriptionally inactivated X and Y chromosomes. In spermatocytes that carry translocations for chromosomes 1 and 13, Rad18Sc protein concentrates on translocation bivalents that are not fully synapsed. The partly synapsed bivalents are often localized in the vicinity of the XY body, and show a very low level of RNA polymerase II, indicating that the chromatin is in a silent configuration similar to transcriptional silencing of the XY body. Thus, Rad18Sc localizes to unsynapsed and silenced chromosome segments during the male meiotic prophase. All known functions of RAD18 in yeast are related to RDB. However, in contrast to Rad18Sc, expression of UBC13 and polη, known to be involved in subsequent steps of RDB, appears to be diminished in the XY body and regions containing the unpaired translocation bivalents. Taken together, these observations suggest that the observed subnuclear localization of Rad18Sc may involve a function outside the context of RDB. This function is probably related to a mechanism that signals the presence of unsynapsed chromosomal regions and subsequently leads to transcriptional silencing of these regions during male meiotic prophase.
AB - In replicative damage bypass (RDB) in yeast, the ubiquitin-conjugating enzyme RAD6 interacts with the ubiquitin ligase RAD18. In the mouse, these enzymes are represented by two homologs of RAD6, HR6a and HR6b, and one homolog of RAD18, Rad18Sc. Expression of these genes and the encoded proteins is ubiquitous, but there is relatively high expression in the testis. We have studied the subcellular localization by immunostaining Rad18Sc and other RDB proteins in mouse primary spermatocytes passing through meiotic prophase in spermatogenesis. The highest Rad18Sc protein level is found at pachytene and diplotene, and the protein localizes mainly to the XY body, a subnuclear region that contains the transcriptionally inactivated X and Y chromosomes. In spermatocytes that carry translocations for chromosomes 1 and 13, Rad18Sc protein concentrates on translocation bivalents that are not fully synapsed. The partly synapsed bivalents are often localized in the vicinity of the XY body, and show a very low level of RNA polymerase II, indicating that the chromatin is in a silent configuration similar to transcriptional silencing of the XY body. Thus, Rad18Sc localizes to unsynapsed and silenced chromosome segments during the male meiotic prophase. All known functions of RAD18 in yeast are related to RDB. However, in contrast to Rad18Sc, expression of UBC13 and polη, known to be involved in subsequent steps of RDB, appears to be diminished in the XY body and regions containing the unpaired translocation bivalents. Taken together, these observations suggest that the observed subnuclear localization of Rad18Sc may involve a function outside the context of RDB. This function is probably related to a mechanism that signals the presence of unsynapsed chromosomal regions and subsequently leads to transcriptional silencing of these regions during male meiotic prophase.
KW - HR6a
KW - HR6b
KW - Meiosis
KW - Rad18
KW - Replicative damage bypass
KW - Ubiquitination
KW - XY body
UR - http://www.scopus.com/inward/record.url?scp=8744313837&partnerID=8YFLogxK
U2 - 10.1242/jcs.01368
DO - 10.1242/jcs.01368
M3 - Article
C2 - 15383616
AN - SCOPUS:8744313837
SN - 0021-9533
VL - 117
SP - 5023
EP - 5033
JO - Journal of Cell Science
JF - Journal of Cell Science
IS - 21
ER -