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ZIP4H (TEX11) deficiency in the mouse impairs meiotic double strand break repair and the regulation of crossing over.

Adelman CA, Petrini JH - PLoS Genet. (2008)

Bottom Line: As is true for hypomorphic Nbs1 (Nbs1(DeltaB/DeltaB)) mice, Zip4h(-/Y) mutant mice were fertile.Achiasmate chromosomes at the first meiotic division were also observed in Zip4h(-/Y) mutants, consistent with the observed reduction in MLH1 focus formation.These results indicate that meiotic functions of Zip4 family members are conserved and support the view that the Mre11 complex and ZIP4H interact functionally during the execution of the meiotic program in mammals.

View Article: PubMed Central - PubMed

Affiliation: Molecular Biology and Genetics Program, Sloan-Kettering Institute, New York, New York, United States of America.

ABSTRACT
We have recently shown that hypomorphic Mre11 complex mouse mutants exhibit defects in the repair of meiotic double strand breaks (DSBs). This is associated with perturbation of synaptonemal complex morphogenesis, repair and regulation of crossover formation. To further assess the Mre11 complex's role in meiotic progression, we identified testis-specific NBS1-interacting proteins via two-hybrid screening in yeast. In this screen, Zip4h (Tex11), a male germ cell specific X-linked gene was isolated. Based on sequence and predicted structural similarity to the S. cerevisiae and A. thaliana Zip4 orthologs, ZIP4H appears to be the mammalian ortholog. In S. cerevisiae and A. thaliana, Zip4 is a meiosis-specific protein that regulates the level of meiotic crossovers, thus influencing homologous chromosome segregation in these organisms. As is true for hypomorphic Nbs1 (Nbs1(DeltaB/DeltaB)) mice, Zip4h(-/Y) mutant mice were fertile. Analysis of spermatocytes revealed a delay in meiotic double strand break repair and decreased crossover formation as inferred from DMC1 and MLH1 staining patterns, respectively. Achiasmate chromosomes at the first meiotic division were also observed in Zip4h(-/Y) mutants, consistent with the observed reduction in MLH1 focus formation. These results indicate that meiotic functions of Zip4 family members are conserved and support the view that the Mre11 complex and ZIP4H interact functionally during the execution of the meiotic program in mammals.

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Zip4h expression in testis sections.Testis sections from adult Zip4h+/Y (A, C) and Zip4h−/Y (B, D) mice were immunohistochemically labeled for ZIP4H (in brown), and counterstained with hematoxylin (in blue). Staining patterns under low magnification (A, B). Higher magnification images showing positively stained zygotene cells of control tubules (C) and absence of staining in mutant tubules at the same stage (D). Black bars represent 50 µm. ZIP4H IP-Western blot from Zip4h+/Y and Zip4h−/Y 12 d.p.p. testis extracts (E), asterisk denotes lower molecular weight species visible only in Zip4h−/Y samples.
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pgen-1000042-g002: Zip4h expression in testis sections.Testis sections from adult Zip4h+/Y (A, C) and Zip4h−/Y (B, D) mice were immunohistochemically labeled for ZIP4H (in brown), and counterstained with hematoxylin (in blue). Staining patterns under low magnification (A, B). Higher magnification images showing positively stained zygotene cells of control tubules (C) and absence of staining in mutant tubules at the same stage (D). Black bars represent 50 µm. ZIP4H IP-Western blot from Zip4h+/Y and Zip4h−/Y 12 d.p.p. testis extracts (E), asterisk denotes lower molecular weight species visible only in Zip4h−/Y samples.

Mentions: To determine the localization of ZIP4H protein, antiserum was raised against mouse ZIP4H in goat and rat using an antigen spanning the region of the protein encoded by the last 4 exons (see Figure 1A for illustration). Immunohistochemical staining of testis sections from wildtype mice indicated ZIP4H-positive cells were localized to the periphery of a subset of tubules (Figure 2A and 2C). Staging of ZIP4H positive tubules and cells [39] indicated that the protein appears in late stage spermatogonia and pre-meiotic cells, is present through the early meiotic stages of leptotene and zygotene, and diminishes to background levels during pachytene (Figure S2, Table S1). Immunofluorescence analysis of spermatocyte spreads using four different ZIP4H antisera did not reveal areas of concentrated ZIP4H localization (data not shown) indicating that either ZIP4H does not localize to discrete sites along SCs or chromatin domains such as the sex body, or enrichment at these sites is insufficient for detection. In this regard, it is noteworthy that with the exception of the sex body, the Mre11 complex exhibits a similar lack of focal presentation on meiotic chromatin [40]. Nevertheless, as also shown for the Mre11 complex, immunohistochemical analyses indicated that ZIP4H is present during meiotic stages when key events take place including DSB formation, repair, synaptonemal complex assembly, and early phases of crossover site establishment.


ZIP4H (TEX11) deficiency in the mouse impairs meiotic double strand break repair and the regulation of crossing over.

Adelman CA, Petrini JH - PLoS Genet. (2008)

Zip4h expression in testis sections.Testis sections from adult Zip4h+/Y (A, C) and Zip4h−/Y (B, D) mice were immunohistochemically labeled for ZIP4H (in brown), and counterstained with hematoxylin (in blue). Staining patterns under low magnification (A, B). Higher magnification images showing positively stained zygotene cells of control tubules (C) and absence of staining in mutant tubules at the same stage (D). Black bars represent 50 µm. ZIP4H IP-Western blot from Zip4h+/Y and Zip4h−/Y 12 d.p.p. testis extracts (E), asterisk denotes lower molecular weight species visible only in Zip4h−/Y samples.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2267488&req=5

pgen-1000042-g002: Zip4h expression in testis sections.Testis sections from adult Zip4h+/Y (A, C) and Zip4h−/Y (B, D) mice were immunohistochemically labeled for ZIP4H (in brown), and counterstained with hematoxylin (in blue). Staining patterns under low magnification (A, B). Higher magnification images showing positively stained zygotene cells of control tubules (C) and absence of staining in mutant tubules at the same stage (D). Black bars represent 50 µm. ZIP4H IP-Western blot from Zip4h+/Y and Zip4h−/Y 12 d.p.p. testis extracts (E), asterisk denotes lower molecular weight species visible only in Zip4h−/Y samples.
Mentions: To determine the localization of ZIP4H protein, antiserum was raised against mouse ZIP4H in goat and rat using an antigen spanning the region of the protein encoded by the last 4 exons (see Figure 1A for illustration). Immunohistochemical staining of testis sections from wildtype mice indicated ZIP4H-positive cells were localized to the periphery of a subset of tubules (Figure 2A and 2C). Staging of ZIP4H positive tubules and cells [39] indicated that the protein appears in late stage spermatogonia and pre-meiotic cells, is present through the early meiotic stages of leptotene and zygotene, and diminishes to background levels during pachytene (Figure S2, Table S1). Immunofluorescence analysis of spermatocyte spreads using four different ZIP4H antisera did not reveal areas of concentrated ZIP4H localization (data not shown) indicating that either ZIP4H does not localize to discrete sites along SCs or chromatin domains such as the sex body, or enrichment at these sites is insufficient for detection. In this regard, it is noteworthy that with the exception of the sex body, the Mre11 complex exhibits a similar lack of focal presentation on meiotic chromatin [40]. Nevertheless, as also shown for the Mre11 complex, immunohistochemical analyses indicated that ZIP4H is present during meiotic stages when key events take place including DSB formation, repair, synaptonemal complex assembly, and early phases of crossover site establishment.

Bottom Line: As is true for hypomorphic Nbs1 (Nbs1(DeltaB/DeltaB)) mice, Zip4h(-/Y) mutant mice were fertile.Achiasmate chromosomes at the first meiotic division were also observed in Zip4h(-/Y) mutants, consistent with the observed reduction in MLH1 focus formation.These results indicate that meiotic functions of Zip4 family members are conserved and support the view that the Mre11 complex and ZIP4H interact functionally during the execution of the meiotic program in mammals.

View Article: PubMed Central - PubMed

Affiliation: Molecular Biology and Genetics Program, Sloan-Kettering Institute, New York, New York, United States of America.

ABSTRACT
We have recently shown that hypomorphic Mre11 complex mouse mutants exhibit defects in the repair of meiotic double strand breaks (DSBs). This is associated with perturbation of synaptonemal complex morphogenesis, repair and regulation of crossover formation. To further assess the Mre11 complex's role in meiotic progression, we identified testis-specific NBS1-interacting proteins via two-hybrid screening in yeast. In this screen, Zip4h (Tex11), a male germ cell specific X-linked gene was isolated. Based on sequence and predicted structural similarity to the S. cerevisiae and A. thaliana Zip4 orthologs, ZIP4H appears to be the mammalian ortholog. In S. cerevisiae and A. thaliana, Zip4 is a meiosis-specific protein that regulates the level of meiotic crossovers, thus influencing homologous chromosome segregation in these organisms. As is true for hypomorphic Nbs1 (Nbs1(DeltaB/DeltaB)) mice, Zip4h(-/Y) mutant mice were fertile. Analysis of spermatocytes revealed a delay in meiotic double strand break repair and decreased crossover formation as inferred from DMC1 and MLH1 staining patterns, respectively. Achiasmate chromosomes at the first meiotic division were also observed in Zip4h(-/Y) mutants, consistent with the observed reduction in MLH1 focus formation. These results indicate that meiotic functions of Zip4 family members are conserved and support the view that the Mre11 complex and ZIP4H interact functionally during the execution of the meiotic program in mammals.

Show MeSH
Related in: MedlinePlus