ENU-induced mutant allele of Dnah1, ferf1, causes abnormal sperm behavior and fertilization failure in mice.

Given attention to both contraception and treatment of infertility, there is a need to identify genes and sequence variants required for mammalian fertility. Recent unbiased mutagenesis strategies have expanded horizons of genetic control of reproduction. Here we show that male mice homozygous for the ethyl-nitroso-urea-induced ferf1 (fertilization failure 1) mutation are infertile, producing apparently normal sperm that does not fertilize oocytes in standard fertilization in vitro fertilization assays.

Oocyte stage-specific effects of MTOR determine granulosa cell fate and oocyte quality in mice.

MTOR (mechanistic target of rapamycin) is a widely recognized integrator of signals and pathways key for cellular metabolism, proliferation, and differentiation. Here we show that conditional knockout (cKO) of in either primordial or growing oocytes caused infertility but differentially affected oocyte quality, granulosa cell fate, and follicular development. cKO of in nongrowing primordial oocytes caused defective follicular development leading to progressive degeneration of oocytes and loss of granulosa cell identity coincident with the acquisition of immature Sertoli cell-like characteristics.

Reproduction: Oocytes Call, Granulosa Cells Connect.

Making functional eggs requires a bidirectional conversation between oocytes and their companion somatic cells. Filopodia emanating from somatic cells carry crucial developmental information to oocytes, and a new study shows that oocytes signal elaboration of this key connection.

SMC5/6 is required for the formation of segregation-competent bivalent chromosomes during meiosis I in mouse oocytes.

SMC complexes include three major classes: cohesin, condensin and SMC5/6. However, the localization pattern and genetic requirements for the SMC5/6 complex during mammalian oogenesis have not previously been examined. In mouse oocytes, the SMC5/6 complex is enriched at the pericentromeric heterochromatin, and also localizes along chromosome arms during meiosis.

Oocyte-dependent activation of MTOR in cumulus cells controls the development and survival of cumulus-oocyte complexes.

Communication between oocytes and their companion somatic cells promotes the healthy development of ovarian follicles, which is crucial for producing oocytes that can be fertilized and are competent to support embryogenesis. However, how oocyte-derived signaling regulates these essential processes remains largely undefined. Here, we demonstrate that oocyte-derived paracrine factors, particularly GDF9 and GDF9-BMP15 heterodimer, promote the development and survival of cumulus-cell-oocyte complexes (COCs), partly by suppressing the expression of Ddit4l, a negative regulator of MTOR, and enabling the activation of MTOR signaling in cumulus cells.

Histone reader BRWD1 targets and restricts recombination to the Igk locus.

B lymphopoiesis requires that immunoglobulin genes be accessible to RAG1-RAG2 recombinase. However, the RAG proteins bind widely to open chromatin, which suggests that additional mechanisms must restrict RAG-mediated DNA cleavage. Here we show that developmental downregulation of interleukin 7 (IL-7)-receptor signaling in small pre-B cells induced expression of the bromodomain-family member BRWD1, which was recruited to a specific epigenetic landscape at Igk dictated by pre-B cell receptor (pre-BCR)-dependent Erk activation.

Mouse BRWD1 is critical for spermatid postmeiotic transcription and female meiotic chromosome stability.

Postmeiotic gene expression is essential for development and maturation of sperm and eggs. We report that the dual bromodomain-containing protein BRWD1, which is essential for both male and female fertility, promotes haploid spermatid-specific transcription but has distinct roles in oocyte meiotic progression. Brwd1 deficiency caused down-regulation of ∼300 mostly spermatid-specific transcripts in testis, including nearly complete elimination of those encoding the protamines and transition proteins, but was not associated with global epigenetic changes in chromatin, which suggests that BRWD1 acts selectively.

Transcriptomic diversification of developing cumulus and mural granulosa cells in mouse ovarian follicles.

Cumulus cells and mural granulosa cells (MGCs) have functionally distinct roles in antral follicles, and comparison of their transcriptomes at a global and systems level can propel future studies on mechanisms underlying their functional diversity. These cells were isolated from small and large antral follicles before and after stimulation of immature mice with gonadotropins, respectively. Both cell types underwent dramatic transcriptomic changes, and differences between them increased with follicular growth.

Amino acid 72 of mouse and human GDF9 mature domain is responsible for altered homodimer bioactivities but has subtle effects on GDF9:BMP15 heterodimer activities.

Growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are oocyte-secreted paralogs of the transforming growth factor beta (TGFbeta) superfamily. In mammals, these two growth factors play critical roles in folliculogenesis. As previously reported, an arginine in the pre-helix loop of GDF5 defines the high binding specificity to its type 1 receptor.

Applying "gold standards" to in-vitro-derived germ cells.

Germ cells are the ultimate stem cells, and reports of their in vitro derivation generate excitement due to potential applications in reproductive medicine. To date, there is no firm evidence that meiosis, the hallmark of gametogenesis, can be faithfully replicated outside of the gonad. We propose benchmarks for evaluating in vitro derivation of germ cells, facilitating realization of their potential.

Cooperative effects of 17β-estradiol and oocyte-derived paracrine factors on the transcriptome of mouse cumulus cells.

Oocyte-derived paracrine factors (ODPFs) and estrogens are both essential for the development and function of ovarian follicles in mammals. Cooperation of these two factors was assessed in vitro using intact cumulus-oocyte complexes, cumulus cells cultured after the removal of oocytes [oocytectomized (OOX) cumulus cells], and OOX cumulus cells cocultured with denuded oocytes, all in the presence or absence of 17β-estradiol (E2). Effects on the cumulus cell transcriptome were assessed by microarray analysis.

Bidirectional communication between oocytes and ovarian follicular somatic cells is required for meiotic arrest of mammalian oocytes.

Coordinated regulation of oocyte and ovarian follicular development is essential for fertility. In particular, the progression of meiosis, a germ cell-specific cell division that reduces the number of chromosomes from diploid to haploid, must be arrested until just before ovulation. Follicular somatic cells are well-known to impose this arrest, which is essential for oocyte-follicle developmental synchrony.

Oocyte differentiation is genetically dissociable from meiosis in mice.

Oogenesis is the process by which ovarian germ cells undertake meiosis and differentiate to become eggs. In mice, Stra8 is required for the chromosomal events of meiosis to occur, but its role in differentiation remains unknown. Here we report Stra8-deficient ovarian germ cells that grow and differentiate into oocyte-like cells that synthesize zonae pellucidae, organize surrounding somatic cells into follicles, are ovulated in response to hormonal stimulation, undergo asymmetric cell division to produce a polar body and cleave to form two-cell embryos upon fertilization.

Growth differentiation factor 9:bone morphogenetic protein 15 heterodimers are potent regulators of ovarian functions.

The TGF-β superfamily is the largest family of secreted proteins in mammals, and members of the TGF-β family are involved in most developmental and physiological processes. Growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), oocyte-secreted paralogs of the TGF-β superfamily, have been shown genetically to control ovarian physiology. Although previous studies found that GDF9 and BMP15 homodimers can modulate ovarian pathways in vitro, the functional species-specific significance of GDF9:BMP15 heterodimers remained unresolved.

Hormonal coordination of natriuretic peptide type C and natriuretic peptide receptor 3 expression in mouse granulosa cells.

Natriuretic peptide type C (NPPC) and its receptor natriuretic peptide receptor 2 (NPR2) regulate cGMP in ovarian follicles and participate in maintaining oocyte meiotic arrest. We investigated the regulation of Nppc expression in mouse granulosa cells in vivo and in vitro. In mural granulosa cells (MGCs) in vivo, eCG caused an increase in Nppc mRNA, and subsequent human chorionic gonadotropin (hCG) treatment caused a decrease.

Meiosis arrest female 1 (MARF1) has nuage-like function in mammalian oocytes.

Orderly regulation of meiosis and protection of germline genomic integrity from transposable elements are essential for male and female gamete development. In the male germline, these processes are ensured by proteins associated with cytoplasmic nuage, but morphologically similar germ granules or nuage have not been identified in mammalian female germ cells. Indeed, many mutations affecting nuage-associated proteins such as PIWI and tudor domain containing proteins 5 and 7 (TDRD5/7) can result in failure of meiosis, up-regulation of retrotransposons, and infertility only in males and not in females.

Luteinizing hormone reduces the activity of the NPR2 guanylyl cyclase in mouse ovarian follicles, contributing to the cyclic GMP decrease that promotes resumption of meiosis in oocytes.

In preovulatory ovarian follicles of mice, meiotic prophase arrest in the oocyte is maintained by cyclic GMP from the surrounding granulosa cells that diffuses into the oocyte through gap junctions. The cGMP is synthesized in the granulosa cells by the transmembrane guanylyl cyclase natriuretic peptide receptor 2 (NPR2) in response to the agonist C-type natriuretic peptide (CNP). In response to luteinizing hormone (LH), cGMP in the granulosa cells decreases, and as a consequence, oocyte cGMP decreases and meiosis resumes.

MARF1 regulates essential oogenic processes in mice.

Development of fertilization-competent oocytes depends on integrated processes controlling meiosis, cytoplasmic development, and maintenance of genomic integrity. We show that meiosis arrest female 1 (MARF1) is required for these processes in mammalian oocytes. Mutations of Marf1 cause female infertility characterized by up-regulation of a cohort of transcripts, increased retrotransposon expression, defective cytoplasmic maturation, and meiotic arrest.

Spata22, a novel vertebrate-specific gene, is required for meiotic progress in mouse germ cells.

The N-ethyl-N-nitrosourea-induced repro42 mutation, identified by a forward genetics strategy, causes both male and female infertility, with no other apparent phenotypes. Positional cloning led to the discovery of a nonsense mutation in Spata22, a hitherto uncharacterized gene conserved among bony vertebrates. Expression of both transcript and protein is restricted predominantly to germ cells of both sexes.

Origins of granulosa cells clarified and complexified by waves.

Temporal differences in granulosa cell specification in the ovary reflect distinct follicle fates by Mork et al: a commentary.

Estradiol promotes and maintains cumulus cell expression of natriuretic peptide receptor 2 (NPR2) and meiotic arrest in mouse oocytes in vitro.

Natriuretic peptide type C (NPPC) and its cognate receptor natriuretic peptide receptor 2 (NPR2) are essential for maintaining meiotic arrest in mouse oocytes residing in Graafian follicles. Cumulus cells, which are associated with the oocyte, express the receptor NPR2, a guanylyl cyclase, whereas mural granulosa cells express ligand NPPC. This study determined the temporal expression of Npr2 and the hormonal factors that participate in regulating its expression and, thereby, in oocyte meiotic arrest.

A-MYB (MYBL1) transcription factor is a master regulator of male meiosis.

The transcriptional regulation of mammalian meiosis is poorly characterized, owing to few genetic and ex vivo models. From a genetic screen, we identify the transcription factor MYBL1 as a male-specific master regulator of several crucial meiotic processes. Spermatocytes bearing a novel separation-of-function allele (Mybl1(repro9)) had subtle defects in autosome synapsis in pachynema, a high incidence of unsynapsed sex chromosomes, incomplete double-strand break repair on synapsed pachytene chromosomes and a lack of crossing over.