The CNOT4 Subunit of the CCR4-NOT Complex is Involved in mRNA Degradation, Efficient DNA Damage Repair, and XY Chromosome Crossover during Male Germ Cell Meiosis
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ABSTRACT: The CCR4-NOT complex is a major mRNA deadenylase in eukaryotes and comprise CNOT6/6L and CNOT7/8, both of which are two types of catalytic subunits, as well as CNOT4, which is a regulatory subunit with previously undetermined functions. These subunits are previously hypothesized to play synergistic biochemical functions; however, their in vivo functions have remained poorly investigated. In this study, we constructed viable Cnot6/6l double knockout mice and the males were fertile, whereas Cnot7–/– male mice have been reported to be infertile. These results are against canonical viewpoints and indicate that CNOT7 has CNOT6/6L-independent functions in vivo. We also demonstrate that the mouse testis has an endogenous complex that contains CNOT7 and CNOT4, but not CNOT6/6L. CNOT4 is required for post-implantation embryo development and meiosis progression during spermatogenesis. Selective knockout of Cnot4 in male germ cells leads to defective DNA damage repair and homologous crossover formation between X and Y chromosomes in a cell autonomous manner. CNOT4 functions as a previously unrecognized mRNA adaptor of CCR4-NOT by targeting mRNAs to CNOT7 for deadenylation of the poly(A) tails, thereby mediating the degradation of a subset of transcripts from the zygotene to pachytene stage. Therefore, the mRNA removal promoted by CNOT4-regulated CCR4-NOT complex during the zygotene to pachytene transition is crucial for the selection of DNA repair pathways, subsequent activation of meiosis-related genes, sex chromosome paring, and ultimately, male fertility.
Project description:CCR4-NOT deadenylase is a major regulator of mRNA turnover in eukaryotes. It contains 2 heterogeneous catalytic subunits encoded by Cnot7/8 and Cnot6/6l genes in vertebrates, respectively. The physiological function of each catalytic subunit was unclear due to potential gene redundancy in vivo. In this study Cnot6/6l double knockout mice were generated. These mice were viable and generally healthy, but females were infertile with irregular estrus cycle and poor ovarian responses to gonadotropins. Follicle-stimulating hormone (FSH) stimulated transcription and translation of mRNAs encoding CNOT6 and CNOT6L in ovarian granulosa cells through the activity of phosphoinositide 3-kinase signaling pathway. Results of transcriptome analyses indicated that FSH downregulated a large number of transcripts in granulosa cells during the transition from pre-antral to antral follicles in a CNOT6/6L-dependent manner. These two deadenylases functioned as key effectors of FSH in altering the developmental programs in granulosa cells and triggered clearance of specific transcripts in growing follicles, particularly those encoding repressing factors of granulosa cell proliferation and steroidogenesis. These results demonstrated that FSH modulates granulosa cells function by stimulating selective translational activation and degradation of existed mRNAs, in additional to inducing de novo gene transcription. Meanwhile, this study provides in vivo evidence that CCR4-NOTCNOT6/6L-mediated mRNA deadenylation is dispensable in most somatic cell types, but is essential for the female reproductive endocrine regulation.
Project description:Expression profiling of isolated populations of prepachytene spermatocytes (LP), pachytene spermatocytes (RP) and spermatids (ST) from PWD and B6 was performed to study the genome wide variation in gene expression between two mouse subspecies. To evaluate the transcriptional difference between B6 and PWD in during meiosis, we compared their transcriptomes in sorted populations of pre-pachytene primary spermatocytes (Leptonema, Zygotene and Pachytene), pachytene spermatocytes (Mid-late pachytene and diplotene) and spermatids.
Project description:Prophase I of male meiosis involves dynamic chromosome segregation processes during early spermatogenesis, including synapsis, meiotic recombination, and cohesion. Genetic defects in genes participating in these processes consistently cause reproduction failure in mice. To identify candidate genes responsible for infertility in humans, we performed expression profiling of mouse spermatogenic cells undergoing meiotic prophase I. Cell fractions enriched in spermatogonia, leptotene/zygotene spermatocytes, or pachytene spermatocytes were separately isolated from mouse testes for RNA extraction. To minimize the contamination of other cell types, we fractionated the testicular cells undergoing the first round of spermatogenesis using Percoll gradient procedure. The cell fractions were characterized by morphological analysis by phase contrast microscopy and Nomarski interference microscopy, and then expression of cell lineage- and spermatogenesis stage-specific genes were examined by RT-PCR. The most enriched fractions for spermatogonia (fraction2 from day8), leptotene/zygotene spermatocytes (fraction5 from day12), and pachytene spermatocytes (fraction8 from day15) were subjected to hybridization on Affymetrix microarrays.
Project description:siRNA-mediated knockdown of CNOT6 and/or CNOT6L, or CNOT7 and CNOT8 compared to control to study role in the regulation of gene expression by these factors.
Project description:Expression profiling of isolated populations of prepachytene spermatocytes (LP), pachytene spermatocytes (RP) and spermatids (ST) from PWD and B6 was performed to study the genome wide variation in gene expression between two mouse subspecies. To evaluate the transcriptional difference between B6 and PWD in during meiosis, we compared their transcriptomes in sorted populations of pre-pachytene primary spermatocytes (Leptonema, Zygotene and Pachytene), pachytene spermatocytes (Mid-late pachytene and diplotene) and spermatids. Populations of pre-pachytene spermatocytes, pachytene spermatocytes and spermatids were isolated from PWD and B6 mice. All populations were isolated in duplicates from two animals. Hence, RNA was prepared from 12 samples (= 2 strains x 3 tissues x 2 replicas) and was then subject to labeling and hybridization on microarray chips.
Project description:Spermatogenesis in MILI-KO mice was blocked completely at early prophase of the first meiosis during the zygotene and early pachytene stage. To analyze the molecular basis of MILI function, we examined the difference between gene expression for MILI-/- and MILI+/- testes. Keywords: total RNAs of day10 testes
Project description:The DSB-machinery, which induces the programmed DNA double-strand breaks (DSBs) in leptotene and zygotene stages during meiosis, needs to be kept in silence after the initiation of pachytene stage to prevent the activation of DSB checkpoint that may lead to meiotic arrest or apoptosis of germ cells. However, the mechanisms underlying this repression remain largely unknown. Here, we report that ZFP541, a germ cell-specific zinc finger protein, is responsible for the suppression of DSBs formation at late pachytene. Lack of Zfp541 in mice leads to generation of DSBs in late pachytene spermatocytes by DSB formation related-proteins and causes male infertility due to meiotic failure. Plated-based scRNA-seq of Zfp541-/- spermatocytes revealed that ZFP541 negatively regulates many meiotic prophase genes, including genes for DSB formation and their upstream transcriptional regulators, in late pachytene spermatocytes. These results were confirmed by 10x single-cell RNA-seq data on spermatogenesis of Zfp541-/- testes, which suggested that Zfp541 is required for repressing the activation of pre-pachytene gene expression programs from early to late pachytene. ZFP541 ChIP-seq on pachytene and diplotene spermatocytes demonstrated that ZFP541 occupies the promoters of meiosis initiators (e.g., Meiosin and Rxra) and a subset of their downstream genes to repress their transcription, and thus prevent the reactivation of pre-pachytene gene expression programs in pachytene spermatocytes. Thus, our results not only revealed the role of ZFP541 in maintaining the repression of pre-pachytene transcriptional programs in pachytene spermatocytes but also provide new insight into the regulation of meiotic progression by timely turning off pre-pachytene genes.
Project description:The DSB-machinery, which induces the programmed DNA double-strand breaks (DSBs) in leptotene and zygotene stages during meiosis, needs to be kept in silence after the initiation of pachytene stage to prevent the activation of DSB checkpoint that may lead to meiotic arrest or apoptosis of germ cells. However, the mechanisms underlying this repression remain largely unknown. Here, we report that ZFP541, a germ cell-specific zinc finger protein, is responsible for the suppression of DSBs formation at late pachytene. Lack of Zfp541 in mice leads to generation of DSBs in late pachytene spermatocytes by DSB formation related-proteins and causes male infertility due to meiotic failure. Plated-based scRNA-seq of Zfp541-/- spermatocytes revealed that ZFP541 negatively regulates many meiotic prophase genes, including genes for DSB formation and their upstream transcriptional regulators, in late pachytene spermatocytes. These results were confirmed by 10x single-cell RNA-seq data on spermatogenesis of Zfp541-/- testes, which suggested that Zfp541 is required for repressing the activation of pre-pachytene gene expression programs from early to late pachytene. ZFP541 ChIP-seq on pachytene and diplotene spermatocytes demonstrated that ZFP541 occupies the promoters of meiosis initiators (e.g., Meiosin and Rxra) and a subset of their downstream genes to repress their transcription, and thus prevent the reactivation of pre-pachytene gene expression programs in pachytene spermatocytes. Thus, our results not only revealed the role of ZFP541 in maintaining the repression of pre-pachytene transcriptional programs in pachytene spermatocytes but also provide new insight into the regulation of meiotic progression by timely turning off pre-pachytene genes.
Project description:The DSB-machinery, which induces the programmed DNA double-strand breaks (DSBs) in leptotene and zygotene stages during meiosis, needs to be kept in silence after the initiation of pachytene stage to prevent the activation of DSB checkpoint that may lead to meiotic arrest or apoptosis of germ cells. However, the mechanisms underlying this repression remain largely unknown. Here, we report that ZFP541, a germ cell-specific zinc finger protein, is responsible for the suppression of DSBs formation at late pachytene. Lack of Zfp541 in mice leads to generation of DSBs in late pachytene spermatocytes by DSB formation related-proteins and causes male infertility due to meiotic failure. Plated-based scRNA-seq of Zfp541-/- spermatocytes revealed that ZFP541 negatively regulates many meiotic prophase genes, including genes for DSB formation and their upstream transcriptional regulators, in late pachytene spermatocytes. These results were confirmed by 10x single-cell RNA-seq data on spermatogenesis of Zfp541-/- testes, which suggested that Zfp541 is required for repressing the activation of pre-pachytene gene expression programs from early to late pachytene. ZFP541 ChIP-seq on pachytene and diplotene spermatocytes demonstrated that ZFP541 occupies the promoters of meiosis initiators (e.g., Meiosin and Rxra) and a subset of their downstream genes to repress their transcription, and thus prevent the reactivation of pre-pachytene gene expression programs in pachytene spermatocytes. Thus, our results not only revealed the role of ZFP541 in maintaining the repression of pre-pachytene transcriptional programs in pachytene spermatocytes but also provide new insight into the regulation of meiotic progression by timely turning off pre-pachytene genes.
Project description:Spermatogenesis in MILI-KO mice was blocked completely at early prophase of the first meiosis during the zygotene and early pachytene stage. To analyze the molecular basis of MILI function, we examined the difference between gene expression for MILI-/- and MILI+/- testes. Experiment Overall Design: To exclude secondary effects, we prepared mRNA from day10 mice. Because the apoptotic cells in KO testis were observed at day11 after birth.