Ubiquitin ligase Rad18Sc localizes to the XY body and to other chromosomal regions that are unpaired and transcriptionally silenced during male meiotic prophase

Laan, Roald van der; Uringa, Evert-Jan; Wassenaar, Evelyne; Hoogerbrugge, Jos W.; Sleddens, Esther; Odijk, Hanny; Roest, Henk P.; Boer, P. de; Hoeijmakers, Jan H.J.; Grootegoed, J. Anton; Baarends, Willy M.

doi:10.1242/jcs.01368

Cited by 48 publications

(43 citation statements)

References 56 publications

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“…HR6A and HR6B show 96% amino acid similarity, and at present we have no indications that HR6A and HR6B perform different activities, either in somatic or in germline cells. In spermatocytes, HR6B localizes mainly on the XY body, together with the putative partner ubiquitin ligase RAD18 (van der Laan et al, 2004). Although H2A K119ub1 is also enriched on the XY body, our findings indicate that HR6B activity is not responsible for this modification.…”

Section: H2a T120ph and Regulation Of Chromatin Organizationmentioning

confidence: 54%

“…In particular, recruitment of the checkpoint kinase ATR by the BRCA1 protein and subsequent phosphorylation of Ser139 of H2AX have been shown to be essential for MSUC (Fernandez-Capetillo et al, 2003;Turner et al, 2004;Turner et al, 2005). Interestingly, H2A K119ub1 is also enriched on the XY body, concomitant with accumulation of the HR6B enzyme van der Laan et al, 2004). However, HR6A-or HR6B-dependent histone modifications in mammalian cells have not been described.…”

Section: Introductionmentioning

confidence: 99%

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Increased phosphorylation and dimethylation of XY body histones in theHr6b-knockout mouse is associated with derepression of the X chromosome

Baarends

Wassenaar

Hoogerbrugge

et al. 2007

Journal of Cell Science

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Mono-ubiquitylated H2A marks the transcriptionally silenced XY body during male meiotic prophase. Concomitant with H2AK119ub1, the ubiquitin-conjugating enzyme HR6B is also enriched on the XY body. We analyzed H2A and H2B ubiquitylation in Hr6b-knockout mouse spermatocytes, but no global changes were detected. Next, we analyzed phosphorylation of the threonine residues T120 and T119 that are adjacent to the K119 and K120 target sites for ubiquitylation in H2A and H2B, respectively. In wild-type cells, H2AT120ph and H2BT119ph mark meiotically unpaired and silenced chromatin, including the XY body. In Hr6b-knockout spermatocytes, the H2BT119ph signal was unchanged, but H2AT120ph was enhanced from late pachytene until metaphase I. Furthermore, we found increased H3K4 dimethylation on the X and Y chromosomes of diplotene Hr6b-knockout spermatocytes, persisting into postmeiotic round spermatids. In these cells, the X and Y chromosomes maintained an unchanged H3K9m2 level, even when this modification was lost from centromeric heterochromatin. Analysis of gene expression showed derepression of X chromosome genes in postmeiotic Hr6b-knockout spermatids. We conclude that HR6B exerts control over different histone modifications in spermatocytes and spermatids, and that this function contributes to the postmeiotic maintenance of X chromosome silencing.

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Section: H2a T120ph and Regulation Of Chromatin Organizationmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Increased phosphorylation and dimethylation of XY body histones in theHr6b-knockout mouse is associated with derepression of the X chromosome

Baarends

Wassenaar

Hoogerbrugge

et al. 2007

Journal of Cell Science

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“…Sc (as described by van der Laan et al [53]), rabbit polyclonal antiubiquitin (DakoCytomation, Glostrup, Denmark), rabbit polyclonal anti-trimethylated H3 lysine 9 (Upstate), rabbit polyclonal anti-Hr6a/b (1:100) (described by van der Laan et al [53]), and rabbit polyclonal anti-␥-H2AX (Upstate). For polyclonal primary antibodies, the secondary antibodies were fluorescein isothiocyanate (Sigma, St. Louis, Mo.…”

Section: Methodsmentioning

confidence: 99%

Silencing of Unpaired Chromatin and Histone H2A Ubiquitination in Mammalian Meiosis

Baarends¹,

Wassenaar²,

Laan

et al. 2005

Molecular and Cellular Biology

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261

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During meiotic prophase in male mammals, the X and Y chromosomes are incorporated in the XY body. This heterochromatic body is transcriptionally silenced and marked by increased ubiquitination of histone H2A. This led us to investigate the relationship between histone H2A ubiquitination and chromatin silencing in more detail. First, we found that ubiquitinated H2A also marks the silenced X chromosome of the Barr body in female somatic cells. Next, we studied a possible relationship between H2A ubiquitination, chromatin silencing, and unpaired chromatin in meiotic prophase. The mouse models used carry an unpaired autosomal region in male meiosis or unpaired X and Y chromosomes in female meiosis. We show that ubiquitinated histone H2A is associated with transcriptional silencing of large chromatin regions. This silencing in mammalian meiotic prophase cells concerns unpaired chromatin regions and resembles a phenomenon described for the fungus Neurospora crassa and named meiotic silencing by unpaired DNA.Chromatin remodeling is at the basis of control of cellspecific gene expression, cell determination, and differentiation. The nucleosome units of chromatin consist of two each of the histones H2A, H2B, H3, and H4. The N-terminal ends of these core histones extend from the nucleosome and can undergo posttranslational covalent modifications, such as methylation, acetylation, phosphorylation, and ADP-ribosylation of specific amino acid residues. Together, these modifications constitute the so-called histone code (45). Interaction of other nuclear proteins with chromatin is dependent on the histone code at specific chromatin regions and determines local chromatin structure, which can be open or closed. A remarkable component of the histone code is ubiquitination of C-terminal lysine residues of histones H2A and H2B. Ubiquitin, a protein of 7 kDa, can be attached to lysine residues of a specific protein substrate through the action of a multienzyme complex containing ubiquitin-activating (E1), ubiquitin-conjugating (E2), and ubiquitin ligase (E3) enzymes. Polyubiquitination can target proteins for degradation by the proteasome (34, 35). Monoubiquitination of histones, however, is a stable modification that does not decrease the half-life of the target histone (56).In the yeast Saccharomyces cerevisiae, histone H2A ubiquitination is not required for cell growth or sporulation (47), but histone H2B ubiquitination is an essential mechanism involved in sporulation (37). Most importantly, it has been shown that ubiquitination of H2B by the ubiquitin-conjugating enzyme RAD6, interacting with the ubiquitin ligase BRE1, is a prerequisite for dimethylation of histone H3 at lysine residues 4 and 79 (5,12,37,46). This mechanism is thought to be associated with potentiation of gene activation. It is not known whether this "trans-histone" mechanism is conserved between yeast and mammals. RAD6 shows marked evolutionary conservation. The two mammalian homologs of yeast RAD6, Hr6a/Ube2a and Hr6b/Ube2b, both show approximately 70% amino...

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“…In fact, specific nonhistone proteins, histone variants (summarized in Fig. 2) and chemically modified histones (by phosphorylation, acetylation, methylation, or ubiquitination; Hoyer-Fender et al, 2000;Khalil et al, 2004;van der Laan et al, 2004) can be found in the condensed XY pair. Some of these proteins may have a direct effect on chromatin condensation; others may contribute to the structure of the unsynapsed axial cores, which undergoes splitting and bulging during meiotic prophase; other proteins may regulate the occurrence of the PAR and eventually the completion of meiotic prophase.…”

Section: The C-terminus Of Scp3 and Xmr Displaysmentioning

confidence: 99%

XY chromosomal bivalent: Nucleolar attraction

Tres

2005

Mol. Reprod. Dev.

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Nucleolar organization by autosomal bivalents occurs during male meiotic prophase in mammalian species. During late leptotene-early zygotene stages, several autosomal bivalents are engaged in ribosomal RNA synthesis. At pachytene stage, nucleolar masses detach from the sites of primary autosomal origin, relocate close to the XY chromosomal pair, and nucleolar components become segregated. In early pachytene, an extensive synaptonemal complex at the pseudoautosomal region, links X and Y chromosomes in close juxtaposition along most of the length of the Y chromosome, except for a terminal region of the Y that diverges from the pairing region. As meiotic prophase advances, X and Y chromosomes progressively desynapse and, at diplotene, the XY pair is associated end-to-end. Xmr (Xlr-related, meiosis regulated) is a protein component of the nucleolus associated to the XY pair and of the asynapsed portions of the X and Y axial cores. Xmr, like SCP3, is a component of the lateral element of the synaptonemal complex. Both share structural homology in their C-terminal region. This region contains several putative coiled-coil domains known to mediate heterodimeric protein-protein interactions and to provide binding sites to regulatory proteins. Like Xmr, the tumor repressor protein BRCA1 is present along the unsynapsed cores of the XY bivalent. Both Xmr and BRCA1 have been implicated in a mechanism leading to chromatin condensation and transcription inactivation of the XY bivalent. The BRCA1-ATR kinase complex, as recent research suggests, triggers the phosphorylation of histone H2AX, which predominates in the condensed chromatin of the XY chromosomal pair. Xmr is not present in the XY bivalent when the expression of histone H2AX is deficient. The role of Xmr in chromatin condensation of the XY bivalent has not been determined. The partial structural homology of SCP3 and Xmr, their distribution along the unsynapsed axial cores of the X and Y chromosomes, and the presence of Xmr in the XY pair-associated nucleolus raises the possibility that Xmr, and other proteins including protein kinases, may be recruited to the nucleolus to perform functions related to chromosomal synapsis, chromatin condensation and recombination processes, as well as cell cycle progression. Mol. Reprod. Dev. 72: 1-6, 2005. ß 2005 Wiley-Liss, Inc.

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Ubiquitin ligase Rad18Sc localizes to the XY body and to other chromosomal regions that are unpaired and transcriptionally silenced during male meiotic prophase

Abstract: SummaryUbiquitin ligase Rad18 Sc localizes to the XY body and to other chromosomal regions that are unpaired and transcriptionally silenced during male meiotic prophase

Cited by 48 publications

References 56 publications

Increased phosphorylation and dimethylation of XY body histones in theHr6b-knockout mouse is associated with derepression of the X chromosome

Increased phosphorylation and dimethylation of XY body histones in theHr6b-knockout mouse is associated with derepression of the X chromosome

Silencing of Unpaired Chromatin and Histone H2A Ubiquitination in Mammalian Meiosis

XY chromosomal bivalent: Nucleolar attraction

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