<i>Drosophila</i> Protamine-Like Mst35Ba and Mst35Bb Are Required for Proper Sperm Nuclear Morphology but Are Dispensable for Male Fertility

Tirmarche, Samantha; Kimura, Shuhei; Sapey-Triomphe, Laure; Sullivan, William M.; Landmann, Frédéric; Loppin, Benjamin

doi:10.1534/g3.114.012724

Cited by 32 publications

(39 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This protein class includes Mst35Ba and Mst35Bb, which are the products of duplicate genes, and Mst77F (Rathke et al 2014). Consistent with the proposed role of SNBPs, males mutant for Mst35Ba and Mst35Bb or Mst77F produce spermatids or sperm with abnormal nuclear shapes (Rathke et al 2010;Tirmarche et al 2014). However, we did not detect abnormalities in sperm (n = 3050) of ddbt Z4344 /Df males, as assayed by staining with the DNA dye DAPI.…”

Section: A Paternal Effect Gene Deadbeat (Ddbt) Encodes a Sperm Nucsupporting

confidence: 73%

The Deadbeat Paternal Effect of Uncapped Sperm Telomeres on Cell Cycle Progression and Chromosome Behavior in Drosophila melanogaster

2016

View full text Add to dashboard Cite

Telomere-capping complexes (TCCs) protect the ends of linear chromosomes from illegitimate repair and end-to-end fusions and are required for genome stability. The identity and assembly of TCC components have been extensively studied, but whether TCCs require active maintenance in nondividing cells remains an open question. Here we show that Drosophila melanogaster requires Deadbeat (Ddbt), a sperm nuclear basic protein (SNBP) that is recruited to the telomere by the TCC and is required for TCC maintenance during genome-wide chromatin remodeling, which transforms spermatids to mature sperm. Ddbt-deficient males produce sperm lacking TCCs. Their offspring delay the initiation of anaphase as early as cycle 1 but progress through the first two cycles. Persistence of uncapped paternal chromosomes induces arrest at or around cycle 3. This early arrest can be rescued by selective elimination of paternal chromosomes and production of gynogenetic haploid or haploid mosaics. Progression past cycle 3 can also occur if embryos have reduced levels of the maternally provided checkpoint kinase Chk2. The findings provide insights into how telomere integrity affects the regulation of the earliest embryonic cell cycles. They also suggest that other SNBPs, including those in humans, may have analogous roles and manifest as paternal effects on embryo quality.KEYWORDS telomere maintenance; telomere capping; cell cycle checkpoint; paternal effect; sperm nuclear basic protein T ELOMERES are the natural ends of linear chromosomes and have distinct properties from broken ends. Multiple proteins are enriched predominantly, if not exclusively, at telomeres and form a capping complex that protects telomeric DNA from engaging in aberrant DNA repair activities. Protein components of the telomere-capping complex (TCC) vary among organisms, in part because species differ in telomeric sequences and whether telomeres are maintained by telomerase or alternative mechanisms (Raffa et al. 2011;Mason et al. 2015). Nonetheless, the TCC's essential functions are well conserved. Failure to assemble TCCs results in telomeric DNA degradation, telomere fusions, and genomic instability.Mutations in at least 12 loci of Drosophila melanogaster lead to telomere fusions in neuroblasts. Their analysis has led to the identification of telomere-enriched and telomereexclusive proteins required for telomere elongation or TCC assembly, maintenance, or function (Cenci et al. 2005;Pimpinelli 2006). Absence of any one component results in telomere fusions but components have distinct activities (Pimpinelli 2006). For example, heterochromatin protein 1a (HP1a) binds modified histone H3-MeK9 and represses transcription of telomeric retrotransposons and telomere elongation. HP1a also binds DNA and this activity is required for its capping function. The TCC protein HOAP binds DNA and HP1a. Although HOAP is required for capping, it does not affect retrotransposon transcription or telomere elongation. A third protein, HipHop, binds both HP1a and HOAP. HOAP and HipHo...

show abstract

Section: A Paternal Effect Gene Deadbeat (Ddbt) Encodes a Sperm Nucsupporting

confidence: 73%

The Deadbeat Paternal Effect of Uncapped Sperm Telomeres on Cell Cycle Progression and Chromosome Behavior in Drosophila melanogaster

2016

View full text Add to dashboard Cite

show abstract

“…To more directly test the possibility that the dhd nuclear phenotype was indeed caused by a delay in SNBP removal, we took advantage of the fact that deletion alleles of both Mst35Ba/b protamine-like genes do not prevent the production of fertilization-competent sperm3839. We reasoned that the previously reported impact of Mst35Ba/b deletion on sperm chromatin compaction3238 could facilitate the SNBP/histone replacement at fertilization in dhd mutant eggs.…”

Section: Resultsmentioning

confidence: 99%

Unlocking sperm chromatin at fertilization requires a dedicated egg thioredoxin in Drosophila

et al. 2016

Self Cite

View full text Add to dashboard Cite

In most animals, the extreme compaction of sperm DNA is achieved after the massive replacement of histones with sperm nuclear basic proteins (SNBPs), such as protamines. In some species, the ultracompact sperm chromatin is stabilized by a network of disulfide bonds connecting cysteine residues present in SNBPs. Studies in mammals have established that the reduction of these disulfide crosslinks at fertilization is required for sperm nuclear decondensation and the formation of the male pronucleus. Here, we show that the Drosophila maternal thioredoxin Deadhead (DHD) is specifically required to unlock sperm chromatin at fertilization. In dhd mutant eggs, the sperm nucleus fails to decondense and the replacement of SNBPs with maternally-provided histones is severely delayed, thus preventing the participation of paternal chromosomes in embryo development. We demonstrate that DHD localizes to the sperm nucleus to reduce its disulfide targets and is then rapidly degraded after fertilization.

show abstract

“…The cysteine-rich ProtA and ProtB are nearly identical and are conserved in other Drosophila species [6]. In addition, Mst77F, a protein similar to the linker histone H1, is also found in mature sperm [5].…”

mentioning

confidence: 97%

“…During the late canoe stage, the transition-protein-like proteins are removed and protamine-like proteins are loaded onto the sperm chromatin [5,6]. The cysteine-rich ProtA and ProtB are nearly identical and are conserved in other Drosophila species [6].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Versager is expressed at the histone-to-protamine transition during spermiogenesis and is required for embryonic chromosome transmission in Drosophila melanogaster

Binder¹,

Wakimoto²,

Davis³

et al. 2017

Res J Dev Biol

View full text Add to dashboard Cite

Background: Chromatin remodeling is one of the most intriguing features of spermiogenesis, during which nuclei undergo drastic morphological changes leading to extensive chromatin compaction. Genetic and cytological accessibility make Drosophila melanogaster a powerful model to study this process. In fruit flies, paternal histones are largely replaced with sperm specific nuclear basic proteins in a highly coordinated manner. This remodeling is essential not only for sperm function but also for proper behavior of paternal chromosomes in the embryo. Our understanding of the changes associated with sperm chromatin and their role in embryonic chromosome behavior is incomplete, and will depend on the identification and characterization of additional components. One such newly identified gene, versager (vrs), is described here. Methods: Chromosome transmission was genetically monitored from vrs Z2566 males using chromosomespecific visible mutations. Recombination and deletion mapping was used to localize the mutation, and DNA sequencing was used to identify the causative lesion. Both in vivo RNAi expression knockdown and rescue by transgene expression of EGFP-tagged protein were used to verify the gene identity. The developmental expression pattern of Vrs was defined based on the EGFP signal in testis relative to RFP-tagged H2Av expression. Behavior of DAPI-stained chromosomes in early embryos from vrs Z2566 males was examined using confocal microscopy. Results: Genetic observations indicated that vrsZ2566 is required in males for high fidelity transmission of paternally derived chromosomes. DNA sequencing revealed that the vrs Z2566 mutation is a missense mutation in Celera predicted gene CG5538 and results in a D2V amino acid substitution. This residue was found to be conserved in Drosophila species and related Diptera. RNAi knockdown of vrs resulted in paternal-effect chromosome loss, and a vrs + -EGFP transgene fully rescued the mutant phenotype. Confocal microscopy of testis revealed nuclear localization of Vrs-EGFP specifically at the canoe stage of spermiogenesis, overlapping with the time of removal of H2Av-RFP at the histone-to-protamine transition. Examination of early stage embryos revealed micronuclei, isolated chromosomes and bridges indicative of chromosome loss events during the first three divisions. Approximately a quarter of later stage embryos arrested with an abnormal number of metaphase and fragmented nuclei. Conclusions: A novel sperm-specific paternal-effect gene, vrs, was identified that is expressed at the histone-to-protamine transition and is important for embryonic chromosome behavior and development. The histone-to-protamine transition may be a developmental period sensitive to perturbations that may lead to embryonic mitotic errors, aneuploidy and developmental arrest.

show abstract

Drosophila Protamine-Like Mst35Ba and Mst35Bb Are Required for Proper Sperm Nuclear Morphology but Are Dispensable for Male Fertility

Cited by 32 publications

References 21 publications

The Deadbeat Paternal Effect of Uncapped Sperm Telomeres on Cell Cycle Progression and Chromosome Behavior in Drosophila melanogaster

The Deadbeat Paternal Effect of Uncapped Sperm Telomeres on Cell Cycle Progression and Chromosome Behavior in Drosophila melanogaster

Unlocking sperm chromatin at fertilization requires a dedicated egg thioredoxin in Drosophila

Versager is expressed at the histone-to-protamine transition during spermiogenesis and is required for embryonic chromosome transmission in Drosophila melanogaster

Contact Info

Product

Resources

About