Combinatory approaches prevent preterm birth profoundly exacerbated by gene-environment interactions

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Abstract

There are currently more than 15 million preterm births each year. We propose that gene-environment interaction is a major contributor to preterm birth. To address this experimentally, we generated a mouse model with uterine deletion of Trp53, which exhibits approximately 50% incidence of spontaneous preterm birth due to premature decidual senescence with increased mTORC1 activity and COX2 signaling. Here we provide evidence that this predisposition provoked preterm birth in 100% of females exposed to a mild inflammatory insult with LPS, revealing the high significance of gene-environment interactions in preterm birth. More intriguingly, preterm birth was rescued in LPS-treated Trp53-deficient mice when they were treated with a combination of rapamycin (mTORC1 inhibitor) and progesterone (P₄), without adverse effects on maternal or fetal health. These results provide evidence for the cooperative contributions of two sites of action (decidua and ovary) toward preterm birth. Moreover, a similar signature of decidual senescence with increased mTORC1 and COX2 signaling was observed in women undergoing preterm birth. Collectively, our findings show that superimposition of inflammation on genetic predisposition results in high incidence of preterm birth and suggest that combined treatment with low doses of rapamycin and P₄ may help reduce the incidence of preterm birth in high-risk women.

Authors

Jeeyeon Cha, Amanda Bartos, Mahiro Egashira, Hirofumi Haraguchi, Tomoko Saito-Fujita, Emma Leishman, Heather Bradshaw, Sudhansu K. Dey, Yasushi Hirota

Macrophages regulate corpus luteum development during embryo implantation in mice

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Abstract

Macrophages are prominent in the uterus and ovary at conception. Here we utilize the Cd11b-Dtr mouse model of acute macrophage depletion to define the essential role of macrophages in early pregnancy. Macrophage depletion after conception caused embryo implantation arrest associated with diminished plasma progesterone and poor uterine receptivity. Implantation failure was alleviated by administration of bone marrow–derived CD11b⁺F4/80⁺ monocytes/macrophages. In the ovaries of macrophage-depleted mice, corpora lutea were profoundly abnormal, with elevated Ptgs2, Hif1a, and other inflammation and apoptosis genes and with diminished expression of steroidogenesis genes Star, Cyp11a1, and Hsd3b1. Infertility was rescued by exogenous progesterone, which confirmed that uterine refractoriness was fully attributable to the underlying luteal defect. In normally developing corpora lutea, macrophages were intimately juxtaposed with endothelial cells and expressed the proangiogenic marker TIE2. After macrophage depletion, substantial disruption of the luteal microvascular network occurred and was associated with altered ovarian expression of genes that encode vascular endothelial growth factors. These data indicate a critical role for macrophages in supporting the extensive vascular network required for corpus luteum integrity and production of progesterone essential for establishing pregnancy. Our findings raise the prospect that disruption of macrophage-endothelial cell interactions underpinning corpus luteum development contributes to infertility in women in whom luteal insufficiency is implicated.

Authors

Alison S. Care, Kerrilyn R. Diener, Melinda J. Jasper, Hannah M. Brown, Wendy V. Ingman, Sarah A. Robertson

BMPR2 is required for postimplantation uterine function and pregnancy maintenance

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Abstract

Abnormalities in cell-cell communication and growth factor signaling pathways can lead to defects in maternal-fetal interactions during pregnancy, including immunologic rejection of the fetal/placental unit. In this study, we discovered that bone morphogenetic protein receptor type 2 (BMPR2) is essential for postimplantation physiology and fertility. Despite normal implantation and early placental/fetal development, deletion of Bmpr2 in the uterine deciduae of mice triggered midgestation abnormalities in decidualization that resulted in abnormal vascular development, trophoblast defects, and a deficiency of uterine natural killer cells. Absence of BMPR2 signaling in the uterine decidua consequently suppressed IL-15, VEGF, angiopoietin, and corin signaling. Disruption of these pathways collectively lead to placental abruption, fetal demise, and female sterility, thereby placing BMPR2 at a central point in the regulation of several physiologic signaling pathways and events at the maternal-fetal interface. Since trophoblast invasion and uterine vascular modification are implicated in normal placentation and fetal growth in humans, our findings suggest that abnormalities in uterine BMPR2-mediated signaling pathways can have catastrophic consequences in women for the maintenance of pregnancy.

Authors

Takashi Nagashima, Qinglei Li, Caterina Clementi, John P. Lydon, Francesco J. DeMayo, Martin M. Matzuk

Fetal-derived adrenomedullin mediates the innate immune milieu of the placenta

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Abstract

The remodeling of maternal uterine spiral arteries (SAs) is an essential process for ensuring low-resistance, high-capacitance blood flow to the growing fetus. Failure of SAs to remodel is causally associated with preeclampsia, a common and life-threatening complication of pregnancy that is harmful to both mother and fetus. Here, using both loss-of-function and gain-of-function genetic mouse models, we show that expression of the pregnancy-related peptide adrenomedullin (AM) by fetal trophoblast cells is necessary and sufficient to promote appropriate recruitment and activation of maternal uterine NK (uNK) cells to the placenta and ultimately facilitate remodeling of maternal SAs. Placentas that lacked either AM or its receptor exhibited reduced fetal vessel branching in the labyrinth, failed SA remodeling and reendothelialization, and markedly reduced numbers of maternal uNK cells. In contrast, overexpression of AM caused a reversal of these phenotypes with a concomitant increase in uNK cell content in vivo. Moreover, AM dose-dependently stimulated the secretion of numerous chemokines, cytokines, and MMPs from uNK cells, which in turn induced VSMC apoptosis. These data identify an essential function for fetal-derived factors in the maternal vascular adaptation to pregnancy and underscore the importance of exploring AM as a biomarker and therapeutic agent for preeclampsia.

Authors

Manyu Li, Nicole M.J. Schwerbrock, Patricia M. Lenhart, Kimberly L. Fritz-Six, Mahita Kadmiel, Kathleen S. Christine, Daniel M. Kraus, Scott T. Espenschied, Helen H. Willcockson, Christopher P. Mack, Kathleen M. Caron

Foxo1 is required in mouse spermatogonial stem cells for their maintenance and the initiation of spermatogenesis

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Abstract

Spermatogonial stem cells (SSCs) capable of self-renewal and differentiation are the foundation for spermatogenesis. Although several factors important for these processes have been identified, the fundamental mechanisms regulating SSC self-renewal and differentiation remain unknown. Here, we investigated a role for the Foxo transcription factors in mouse spermatogenesis and found that Foxo1 specifically marks mouse gonocytes and a subset of spermatogonia with stem cell potential. Genetic analyses showed that Foxo1 was required for both SSC homeostasis and the initiation of spermatogenesis. Combined deficiency of Foxo1, Foxo3, and Foxo4 resulted in a severe impairment of SSC self-renewal and a complete block of differentiation, indicating that Foxo3 and Foxo4, although dispensable for male fertility, contribute to SSC function. By conditional inactivation of 3-phosphoinositide–dependent protein kinase 1 (Pdk1) and phosphatase and tensin homolog (Pten) in the male germ line, we found that PI3K signaling regulates Foxo1 stability and subcellular localization, revealing that the Foxos are pivotal effectors of PI3K-Akt signaling in SSCs. We also identified a network of Foxo gene targets — most notably Ret — that rationalized the maintenance of SSCs by the Foxos. These studies demonstrate that Foxo1 expression in the spermatogenic lineage is intimately associated with the stem cell state and revealed what we believe to be novel Foxo-dependent mechanisms underlying SSC self-renewal and differentiation, with implications for common diseases, including male infertility and testicular cancer, due to abnormalities in SSC function.

Authors

Meredith J. Goertz, Zhuoru Wu, Teresa D. Gallardo, F. Kent Hamra, Diego H. Castrillon

Death effector domain–containing protein (DEDD) is required for uterine decidualization during early pregnancy in mice

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Abstract

During intrauterine life, the mammalian embryo survives via its physical connection to the mother. The uterine decidua, which differentiates from stromal cells after implantation in a process known as decidualization, plays essential roles in supporting embryonic growth before establishment of the placenta. Here we show that female mice lacking death effector domain–containing protein (DEDD) are infertile owing to unsuccessful decidualization. In uteri of Dedd–/– mice, development of the decidual zone and the surrounding edema after embryonic implantation was defective. This was subsequently accompanied by disintegration of implantation site structure, leading to embryonic death before placentation. Polyploidization, a hallmark of mature decidual cells, was attenuated in DEDD-deficient cells during decidualization. Such inefficient decidualization appeared to be caused by decreased Akt levels, since polyploidization was restored in DEDD-deficient decidual cells by overexpression of Akt. In addition, we showed that DEDD associates with and stabilizes cyclin D3, an important element in polyploidization, and that overexpression of cyclin D3 in DEDD-deficient cells improved polyploidization. These results indicate that DEDD is indispensable for the establishment of an adequate uterine environment to support early pregnancy in mice.

Authors

Mayumi Mori, Miwako Kitazume, Rui Ose, Jun Kurokawa, Kaori Koga, Yutaka Osuga, Satoko Arai, Toru Miyazaki

Sirt3 protects in vitro–fertilized mouse preimplantation embryos against oxidative stress–induced p53-mediated developmental arrest

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Abstract

Sirtuins are a phylogenetically conserved NAD+-dependent protein deacetylase/ADP-ribosyltransferase family implicated in diverse biological processes. Several family members localize to mitochondria, the function of which is thought to determine the developmental potential of preimplantation embryos. We have therefore characterized the role of sirtuins in mouse preimplantation development under in vitro culture conditions. All sirtuin members were expressed in eggs, and their expression gradually decreased until the blastocyst stage. Treatment with sirtuin inhibitors resulted in increased intracellular ROS levels and decreased blastocyst formation. These effects were recapitulated by siRNA-induced knockdown of Sirt3, which is involved in mitochondrial energy metabolism, and in Sirt3–/– embryos. The antioxidant N-acetyl-L-cysteine and low-oxygen conditions rescued these adverse effects. When Sirt3-knockdown embryos were transferred to pseudopregnant mice after long-term culture, implantation and fetal growth rates were decreased, indicating that Sirt3-knockdown embryos were sensitive to in vitro conditions and that the effect was long lasting. Further experiments revealed that maternally derived Sirt3 was critical. Sirt3 inactivation increased mitochondrial ROS production, leading to p53 upregulation and changes in downstream gene expression. The inactivation of p53 improved the developmental outcome of Sirt3-knockdown embryos, indicating that the ROS-p53 pathway was responsible for the developmental defects. These results indicate that Sirt3 plays a protective role in preimplantation embryos against stress conditions during in vitro fertilization and culture.

Authors

Yumiko Kawamura, Yasunobu Uchijima, Nanao Horike, Kazuo Tonami, Koichi Nishiyama, Tomokazu Amano, Tomoichiro Asano, Yukiko Kurihara, Hiroki Kurihara

Uterine-specific p53 deficiency confers premature uterine senescence and promotes preterm birth in mice

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Abstract

Many signaling pathways that contribute to tumorigenesis are also functional in pregnancy, although they are dysregulated in the former and tightly regulated in the latter. Transformation-related protein 53 (Trp53), which encodes p53, is a tumor suppressor gene whose mutation is strongly associated with cancer. However, its role in normal physiological processes, including female reproduction, is poorly understood. Mice that have a constitutive deletion of Trp53 exhibit widespread development of carcinogenesis at early reproductive ages, compromised spermatogenesis, and fetal exencephaly, rendering them less amenable to studying the role of p53 in reproduction. To overcome this obstacle, we generated mice that harbor a conditional deletion of uterine Trp53 and examined pregnancy outcome in females with this genotype. These mice had normal ovulation, fertilization, and implantation; however, postimplantation uterine decidual cells showed terminal differentiation and senescence-associated growth restriction with increased levels of phosphorylated Akt and p21, factors that are both known to participate in these processes in other systems. Strikingly, uterine deletion of Trp53 increased the incidence of preterm birth, a condition that was corrected by oral administration of the selective COX2 inhibitor celecoxib. We further generated evidence to suggest that deletion of uterine Trp53 induces preterm birth through a COX2/PGF synthase/PGF2α pathway. Taken together, our observations underscore what we believe to be a new critical role of uterine p53 in parturition.

Authors

Yasushi Hirota, Takiko Daikoku, Susanne Tranguch, Huirong Xie, Heather B. Bradshaw, Sudhansu K. Dey

PICK1 deficiency causes male infertility in mice by disrupting acrosome formation

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Abstract

Protein interacting with C kinase 1 (PICK1) is a peripheral membrane protein involved in protein trafficking, a function that has been well characterized in neurons. Here, we report that male mice deficient in PICK1 are infertile and have a phenotype resembling the human disease globozoospermia. The primary defect in the testes of Pick1-knockout mice was fragmentation of acrosomes in the early stages of spermiogenesis. This fragmentation was followed by defects in nuclear elongation and mitochondrial sheath formation, leading to round-headed sperm, reduced sperm count, and severely impaired sperm motility. We found that PICK1 interacted with Golgi-associated PDZ- and coiled-coil motif–containing protein (GOPC) and the primary catalytic subunit of protein kinase 2 (CK2α′), proteins whose deficiencies lead to globozoospermia in mice. PICK1 was highly expressed in round spermatids and localized to Golgi-derived proacrosomal granules. GOPC colocalized with PICK1 in the Golgi region and facilitated formation of PICK1-positive clusters. Furthermore, there was an increase in apoptosis in the seminiferous tubules of Pick1–/– mice, a phenotype also seen in CK2α′-deficient mice. Our results suggest that PICK1 is involved in vesicle trafficking from the Golgi apparatus to the acrosome and cooperates with other proteins such as GOPC and CK2α′ in acrosome biogenesis.

Authors

Nan Xiao, Chuen Kam, Chong Shen, Wenying Jin, Junqi Wang, Kwong Man Lee, Liwen Jiang, Jun Xia

Human sperm devoid of PLC, zeta 1 fail to induce Ca²⁺ release and are unable to initiate the first step of embryo development

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Abstract

Egg activation, which is the first step in the initiation of embryo development, involves both completion of meiosis and progression into mitotic cycles. In mammals, the fertilizing sperm delivers the activating signal, which consists of oscillations in free cytosolic Ca2+ concentration ([Ca2+]i). Intracytoplasmic sperm injection (ICSI) is a technique that in vitro fertilization clinics use to treat a myriad of male factor infertility cases. Importantly, some patients who repeatedly fail ICSI also fail to induce egg activation and are, therefore, sterile. Here, we have found that sperm from patients who repeatedly failed ICSI were unable to induce [Ca2+]i oscillations in mouse eggs. We have also shown that PLC, zeta 1 (PLCZ1), the sperm protein thought to induce [Ca2+]i oscillations, was localized to the equatorial region of wild-type sperm heads but was undetectable in sperm from patients who had failed ICSI. The absence of PLCZ1 in these patients was further confirmed by Western blot, although genomic sequencing failed to reveal conclusive PLCZ1 mutations. Using mouse eggs, we reproduced the failure of sperm from these patients to induce egg activation and rescued it by injection of mouse Plcz1 mRNA. Together, our results indicate that the inability of human sperm to initiate [Ca2+]i oscillations leads to failure of egg activation and sterility and that abnormal PLCZ1 expression underlies this functional defect.

Authors

Sook-Young Yoon, Teru Jellerette, Ana Maria Salicioni, Hoi Chang Lee, Myung-sik Yoo, Kevin Coward, John Parrington, Daniel Grow, Jose B. Cibelli, Pablo E. Visconti, Jesse Mager, Rafael A. Fissore