Species: mouse
Mutation name: None
type: null mutation
fertility: embryonic lethal
Comment: Sirard et al. (1998) demonstrated that homozygous Smad4 mutant mice died before embryonic day 7.5. Mutant embryos have reduced size, fail to gastrulate or express a mesodermal marker, and show abnormal visceral endoderm development. Growth retardation of the Smad4-deficient embryos results from reduced cell proliferation rather than increased apoptosis. Aggregation of mutant Smad4 embryonic stem cells with wildtype tetraploid morulae rescued the gastrulation defect.

Species: mouse
Mutation name: None
type: null mutation
fertility: embryonic lethal
Comment: Differential requirements for Smad4 in TGF{beta}-dependent patterning of the early mouse embryo Chu GC, et al . Genetic and biochemical data have identified Smad4 as a key intracellular effector of the transforming growth factor beta (TGFbeta superfamily of secreted ligands. In mouse, Smad4-null embryos do not gastrulate, a phenotype consistent with loss of other TGFbeta-related signaling components. Chimeric analysis reveals a primary requirement for Smad4 in the extra-embryonic lineages; however, within the embryo proper, characterization of the specific roles of Smad4 during gastrulation and lineage specification remains limited. We have employed a Smad4 conditional allele to specifically inactivate the Smad4 gene in the early mouse epiblast. Loss of Smad4 in this tissue results in a profound failure to pattern derivatives of the anterior primitive streak, such as prechordal plate, node, notochord and definitive endoderm. In contrast to these focal defects, many well-characterized TGFbeta- and Bmp-regulated processes involved in mesoderm formation and patterning are surprisingly unaffected. Mutant embryos form abundant extra-embryonic mesoderm, including allantois, a rudimentary heart and middle primitive streak derivatives such as somites and lateral plate mesoderm. Thus, loss of Smad4 in the epiblast results not in global developmental abnormalities but instead in restricted patterning defects. These results suggest that Smad4 potentiates a subset of TGFbeta-related signals during early embryonic development, but is dispensable for others.

Species: mouse
Mutation name: None
type: null mutation
fertility: subfertile
Comment: Premature luteinization and cumulus cell defects in ovarian-specific Smad4 knockout mice. Pangas SA et al. SMAD4 is a central component of the TGFbeta superfamily signaling pathway. Within the ovary, TGFbeta-related proteins play crucial roles in controlling granulosa cell growth, differentiation, and steroidogenesis. To study the in vivo roles of SMAD4 during follicle development, we generated an ovarian conditional knockout of Smad4 using the cre/loxP recombination system. Smad4 ovarian-specific knockout mice are subfertile with decreasing fertility over time and multiple defects in folliculogenesis. Regulation of steroidogenesis is disrupted in the Smad4 conditional knockout, leading to increased levels of serum progesterone. In addition, severe cumulus cell defects are present both in vivo and when assayed in vitro. These findings demonstrate that disrupting signaling through SMAD4 in the ovarian granulosa cells leads to premature luteinization of granulosa cells and eventually premature ovarian failure, thereby demonstrating key in vivo roles of TGFbeta superfamily signaling in the timing of granulosa cell differentiation.

Species: mouse
Mutation name: None
type: null mutation
fertility: subfertile
Comment: Minimal Fertility Defects in Mice Deficient in Oocyte-Expressed Smad4. Li X et al. Bidirectional signaling between oocytes and granulosa cells is required for normal folliculogenesis. Oocyte-secreted members of the transforming growth factor beta (TGFB) family, growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), are well known mediators of granulosa cell function, and deletion in granulosa cells of Smad4, the common SMAD mediating all canonical TGFB-related protein signals, results in infertility. Reciprocal signaling by granulosa cell-expressed TGFB family ligands, such as activin, to the oocyte during follicle development has been proposed but not tested in vivo using conditional knockout mice. Therefore, we generated two oocyte-specific conditional knockout models for the common SMAD, Smad4, using cre recombinase expression from either the zona pellucida 3 (Zp3) or Gdf9 promoter. Cre expression from the Gdf9 promoter occurs at a slightly earlier time point in follicle development than from Zp3. Deletion of Smad4 using Zp3cre had no effect on fertility, while deletion of Smad4 with Gdf9icre resulted in a slight, but significant, reduction in litter size. These mouse models suggest a novel, although minor, role for Smad4 in the oocyte restricted to the primordial follicle stage.

Species: mouse
Mutation name: None
type: null mutation
fertility: subfertile
Comment: Selective Smad4 Knockout in Ovarian Preovulatory Follicles Results in Multiple Defects in Ovulation. Yu C et al. The TGF-?signaling pathway is involved with multiple processes in the mammalian ovary, including primordial follicle formation, granulosa cell (GC) proliferation, follicle atresia, ovulation, and feedback regulation between the pituitary and ovary. The transcriptional factor SMAD4 is the central component of the canonical TGF-?signaling pathway. Smad4 knockout using Amhr2-Cre, which is expressed in GCs of immature developing follicles, causes premature luteinization. In this study, we specifically depleted Smad4 in GCs of preovulatory follicles using Cyp19-Cre mice. As different from results with Smad4(fl/fl);Amhr2-Cre mice, Smad4 depletion in preovulatory follicles did not cause premature luteinization or suppress GC proliferation; rather, it increased follicle atresia. In addition, Nppc and Npr2 expressions were reduced by Smad4 depletion; thus, their effect of maintaining oocyte meiotic arrest was weakened in Smad4 conditional knockout mice. Smad4(fl/fl);Cyp19-Cre female mice were subfertile and had irregular estrous cycles and ovulation defects. Smad4 knockout also blocked luteinizing hormone (LH)-induced cumulus expansion and follicle rupture, but not oocyte meiotic resumption. Our results also indicated that SMAD4 was required for LH-stimulated activation of ERK1/2 and the expressions of ovulation-related genes. The defects arising from SMAD4 depletion could not be rescued by intra-ovarian mediators of LH actions, such as EGF-like factors and prostaglandin E2. Furthermore, corpus lutea did not form in Smad4(fl/fl);Cyp19-Cre female mice, indicating that SMAD4 was crucial for GCs terminal differentiation. Thus, by characterizing the ovarian phenotypes of preovulatory follicle-specific Smad4 knockout mice, we identified the developmental stage-specific functions of the canonical TGF-?signaling pathway in ovulation and luteinization.

Species: mouse
Mutation name: None
type: null mutation
fertility: infertile - ovarian defect
Comment: TGF signaling promotes juvenile granulosa cell tumorigenesis by suppressing apoptosis. Mansouri-Attia N 2014 et al. Molecular changes that give rise to granulosa cell tumors of the ovary (GCT) are not well understood. Previously, we showed that deletion in granulosa cells of the bone morphogenetic protein (BMP) receptor-signaling transcription factors, Smad1 and Smad5, causes development of metastatic granulosa cell tumors that phenocopies the juvenile form of granulosa cell tumors (JGCT) in humans. The transforming growth factor (TGF)-SMAD2/3 pathway is active in JGCT but its role is unknown. We tested the in vivo contribution of TGF-SMAD signaling to JGCT development by genetically deleting the common Smad4 from Smad1/5 double knockout mice. Smad1/5/4 triple knockout mice were sterile, and had significantly increased survival and delayed tumor development compared to the Smad1/5 double knockout mice. The few tumors that did develop were smaller, showed no evidence of metastasis, and had increased apoptosis. In the human JGCT cell line (COV434), TGF1 increased viability by inhibiting apoptosis through a TGF type I receptor (TGFRI)-dependent repression of caspase activity and inhibition of PARP cleavage. These data support a tumor-promoting function of TGF in JGCT through its ability to repress apoptosis. /////////////////////////

Species: mouse
Mutation name:
type: null mutation
fertility: infertile - ovarian defect
Comment: Sexual Fate Change of XX Germ Cells Caused by the Deletion of SMAD4 and STRA8 Independent of Somatic Sex Reprogramming. Wu Q et al. (2016) The differential programming of sperm and eggs in gonads is a fundamental topic in reproductive biology. Although the sexual fate of germ cells is believed to be determined by signaling factors from sexually differentiated somatic cells in fetal gonads, the molecular mechanism that determines germ cell fate is poorly understood. Herein, we show that mothers against decapentaplegic homolog 4 (SMAD4) in germ cells is required for female-type differentiation. Germ cells in Smad4-deficient ovaries respond to retinoic acid signaling but fail to undergo meiotic prophase I, which coincides with the weaker expression of genes required for follicular formation, indicating that SMAD4 signaling is essential for oocyte differentiation and meiotic progression. Intriguingly, germline-specific deletion of Smad4 in Stra8-null female germ cells resulted in the up-regulation of genes required for male gonocyte differentiation, including Nanos2 and PLZF, suggesting the initiation of male-type differentiation in ovaries. Moreover, our transcriptome analyses of mutant ovaries revealed that the sex change phenotype is achieved without global gene expression changes in somatic cells. Our results demonstrate that SMAD4 and STRA8 are essential factors that regulate the female fate of germ cells.//////////////////