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Dlx5 and Dlx6 are two closely associated homeobox genes which code for transcription factors involved in the control of steroidogenesis and reproduction. Inactivation of Dlx5/6 in the mouse results in a Leydig cell defect in the male and in ovarian insufficiency in the female. DLX5/6 are also strongly expressed by the human endometrium but their function in the uterus is unknown. The involvement of DLX5/6 in human uterine pathology is suggested by their strong downregulation in endometriotic lesions and upregulation in endometrioid adenocarcinomas. We first show that Dlx5/6 expression begins in Mullerian ducts epithelia and persists then in the uterine luminal and glandular epithelia throughout post-natal maturation and in the adult. We then use a new mouse model in which Dlx5 and Dlx6 can be simultaneously inactivated in the endometrium using a Pgr(cre/+) allele. Post-natal inactivation of Dlx5/6 in the uterus results in sterility without any obvious ovarian involvement. The uteri of Pgr(cre/+); Dlx5/6(flox/flox) mice present very few uterine glands and numerous abnormally large and branched invaginations of the uterine lumen. In Dlx5/6 mutant uteri, the expression of genes involved in gland formation (Foxa2) and in epithelial remodelling during implantation (Msx1) is significantly reduced. Furthermore, we show that DLX5 is highly expressed in human endometrial glandular epithelium and that its expression is affected in endometriosis. We conclude that Dlx5 and Dlx6 expression determines uterine architecture and adenogenesis and is needed for implantation. Given their importance for female reproduction, DLX5 and DLX6 must be regarded as interesting targets for future clinical research.

My thesis is concerned with the involvement of Foxl2, Dlx5 and Dlx6 genes in the development and function of the uterus.In the uterus, Foxl2 expression is visible from birth in the mesenchyme and during the postnatal maturation in the stroma and the myometrium. The conditional invalidation of Foxl2 by the progesterone receptor (Pgr cre / +) causes infertility. The uterus of these mice has a decrease of the stroma thickness and the myometrial layer is hypertrophic and disorganized. The conditional mutants lack the smooth muscle cell layer surrounding the blood vessels in the stroma. The study by qPCR shows that inactivation of Foxl2 deregulates the expression of certain Wnt genes involved in the maturation of the uterus.Dlx5 and Dlx6 meanwhile, are present in the uterine epithelium from E15.5. The conditional invalidation of Dlx5 and Dlx6 by the action of Pgr cre / + induced infertility. These mice present abnormally large invaginations and a very small number of uterine glands. These defects are related to a deregulation of key genes in the formation of glands like Wnt7a and Foxa2.In conclusion, our data show that Foxl2 has a crucial role in the differentiation and organization of the stroma and myometrium. Dlx5 and Dlx6 play a key role in the generation of uterine glands, necessary in adults for the embryo implantation.; Mon travail de thèse s’intéresse à l’implication des gènes Foxl2, Dlx5 et Dlx6 dans le développement et la fonction de l’utérus.Dans l'utérus, l’expression de Foxl2 est visible dès la naissance dans le mésenchyme qui, pendant la maturation post-natale, donne origine au stroma et au myomètre. L’invalidation conditionnelle de Foxl2 par le récepteur de la progestérone (Pgr cre / +) provoque une infertilité. L’utérus de ces souris présente une diminution de la taille du stroma, un myomètre hypertrophique et désorganisé et une absence de la couche de cellule musculaire lisse entourant les vaisseaux sanguins dans le stroma. L’étude par qPCR montre que l’inactivation de Foxl2 dérégule l’expression de certains gènes Wnt, impliqués dans la maturation utérine.Dlx5 et Dlx6 quant à eux, sont présents dans l'épithélium utérin à partir de E15.5. L’invalidation conditionnelle de Dlx5 et Dlx6 par l’action de la Pgr cre / + induit une infertilité. Ces souris ont de nombreuses invaginations anormalement larges et un nombre très réduit de glandes utérines. Ces défauts sont liés à une dérégulation de gènes clés dans la formation des glandes comme Wnt7a et Foxa2.En conclusion, nos données montrent que Foxl2 a un rôle crucial dans la différenciation et l’organisation du stroma et du myomètre et que Dlx5 et Dlx6 jouent un rôle primordial dans la génération des glandes utérines, nécessaires chez l’adulte à l’implantation de l’embryon.

Blepharophimosis, ptosis, epicanthus-inversus syndrome (BPES) is an autosomal dominant genetic disorder characterized by narrow palpebral fissures and eyelid levator muscle defects. BPES is often associated to premature ovarian insufficiency (BPES type I). FOXL2, a member of the forkhead transcription factor family, is the only gene known to be mutated in BPES. Foxl2 is essential for maintenance of ovarian identity, but the developmental origin of the facial malformations of BPES remains, so far, unexplained. In this study, we provide the first detailed account of the developmental processes leading to the craniofacial malformations associated to Foxl2. We show that, during development, Foxl2 is expressed both by Cranial Neural Crest Cells (CNCCs) and by Cranial Mesodermal Cells (CMCs), which give rise to skeletal (CNCCs and CMCs) and muscular (CMCs) components of the head. Using mice in which Foxl2 is selectively inactivated in either CNCCs or CMCs, we reveal that expression of Foxl2 in CNCCs is essential for the development of extraocular muscles. Indeed, inactivation of Foxl2 in CMCs has only minor effects on muscle development, whereas its inactivation in CNCCs provokes a severe hypoplasia of the levator palpabrae superioris and of the superior and inferior oblique muscles. We further show that Foxl2 deletion in either CNCCs or CMCs prevents eyelid closure and induces subtle skeletal developmental defects. Our results provide new insights in the complex developmental origin of human BPES and could help to understand the origin of other ocular anomalies associated to this syndrome.

International audience; Foxl2 codes for a forkhead/HNF3 transcription factor essential for follicular maturation and maintenance of ovarian identity. FOXL2 mutations are associated with Blepharophimosis, Ptosis and Epicanthus inversus Syndrome (BPES) characterized by eyelid malformations (types I and II) and premature ovarian insufficiency (type I). We show that Foxl2 is not only expressed by the ovary, but also by other components of the mouse female reproductive tract, including the uterus, the cervix and the oviduct. In the uterus, Foxl2 expression is first observed in the neonatal mesenchyme and, during uterine maturation, persists in the stroma and in the deep inner myometrial layer (IML). In the adult, Foxl2 is expressed in the differentiated stromal layer, but no longer in the myometrium. Conditional deletion of Foxl2 in the postnatal (PN) uterus using Progesterone Receptor-cre (Pgr(cre/+)) mice results in infertility. During PN uterine maturation Pgr(cre/+); Foxl2(flox/flox) mice present a severely reduced thickness of the stroma layer and an hypertrophic, disorganized IML. In adult Pgr(cre/+); Foxl2(flox/flox) mice a supplementary muscular layer is present at the stroma/myometrium border and vascular smooth muscle cells fail to form a coherent layer around uterine arteries. Wnt signalling pathways play a central role in uterine maturation; in Pgr(cre/+); Foxl2(flox/flox) mice, Wnt genes are deregulated suggesting that Foxl2 acts through these signals. In humans, thickening of the IML (also called "junctional zone") is associated with reduced fertility, endometriosis and adenomyosis. Our data suggest that Foxl2 has a crucial role in PN uterine maturation and could help to understand sub-fertility predisposition in women.

International audience; Primary ovarian insufficiency (POI) is characterized by the loss of ovarian function before the age of 40 in humans. Although most cases of POI are idiopathic, many are familial, underlying a genetic origin of the disease. Mutations in genes involved in the control of steroidogenesis, such as NR5A1 (SF-1, Steroidogenic Factor 1), CYP17, CYP19A1 (aromatase), StAR (Steroidogenic Acute Regulatory), and the forkhead transcription factor FOXL2 have been associated with different forms of POI. In males, the homeobox transcription factors Dlx5 and Dlx6 are involved in the control of steroidogenesis through the activation of GATA4-induced-StAR transcription. Here, we analyze the potential involvement of Dlx5 and Dlx6 in female reproduction. To this end, we make use of an existing mouse model in which Dlx5 and Dlx6 are simultaneously disrupted. We show that: (i) allelic reduction of Dlx5 and Dlx6 in the mouse results in a POI-like phenotype, characterized by reduced fertility and early follicular exhaustion; (ii) in granulosa cell lines, a reciprocal regulation exists between Dlx5 and Foxl2; (iii) in the mouse ovary, allelic reduction of Dlx5/6 results in the upregulation of Foxl2. We propose that the mutual regulation between Dlx5/6 and Foxl2 and their opposite effects on StAR expression might contribute to determine the homeostatic control of steroidogenesis within the ovary. Dysregulation of this homeostatic control would result in abnormal follicular maturation and reduced fertility. Our results bring new elements to our conceptual model of follicle maturation and maintenance and provide new potential genetic targets for cases of familial POI.