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N 6 -threonyl-carbamoylation of adenosine 37 of ANN-type tRNAs (t 6 A) is a universal modification essential for translational accuracy and efficiency. The t 6 A pathway uses two sequentially acting enzymes, YRDC and OSGEP, the latter being a subunit of the multiprotein KEOPS complex. We recently identified mutations in genes encoding four out of the five KEOPS subunits in children with Galloway-Mowat syndrome (GAMOS), a clinically heterogeneous autosomal recessive disease characterized by early-onset steroid-resistant nephrotic syndrome and microcephaly. Here we show that mutations in YRDC cause an extremely severe form of GAMOS whereas mutations in GON7 , encoding the fifth KEOPS subunit, lead to a milder form of the disease. The crystal structure of the GON7/LAGE3/OSGEP subcomplex shows that the intrinsically disordered GON7 protein becomes partially structured upon binding to LAGE3. The structure and cellular characterization of GON7 suggest its involvement in the cellular stability and quaternary arrangement of the KEOPS complex.

The mammalian female reproductive tract develops from the Müllerian ducts which differentiate, in a cranial to caudal direction, into oviducts, uterine horns, cervix and the anterior vagina. The developmental processes taking place during this organogenesis are notably under the control of steroid hormones, such as members of the Wnt and Hox families, which regulate key developmental genes. At later stages, steroid hormones also participate in the development of the female genital tract. Chemical compounds homologous to steroids can thus act as agonists or antagonists in fetuses exposed to them. These so-called endocrine disruptors are nowadays found in increasing amounts in the environment and may therefore have a particular impact on such developing organs. Epidemiological studies have revealed that endocrine disruptors have had drastic effects on female health and fertility during the last decades. Furthermore, these adverse effects might be transmitted to subsequent generations through epigenetic modifications. Given the potential hazard of inherited epigenetic marks altering reproduction and/or human health, such molecular mechanisms must be urgently investigated. This review aims to summarize the cellular and molecular mechanisms involved in female genital tract development, to highlight key genes involved in this process and to present epigenetic mechanisms triggered by endocrine disruptors and their consequences in regard to female reproductive tract development. KEY WORDS: genital tract, Hox, Wnt, genetics, epigenetics Development of the urogenital system Relation between urinary and genital tractsMammalian genital tract development is closely related to the urinary system embryogenesis. This relation is ancient in evolution and phylogenetically well conserved. In simple organisms like annelids, they both consist in metamerized nephritic tubules composed of a ciliated funnel oriented towards the coelomic cavity and connected to a vascularised duct that opens to the exterior. This system is involved in metabolites and mature genital cells excretion. In higher vertebrates, the urogenital apparatus comprises the kidneys, gonads, urinary and reproductive ducts. The urinary tract embryonic formation is the result of a three steps process that gives rise to three successive structures emerging rostrocaudally in the intermediate mesoderm. Nephrotomes first develop in the cervical part of the embryo; they consist in a ciliated funnel emerging in the coelomic cavity and in a nephritic tubule Int. J. Dev. Biol. 53: 411-424 (2009) doi: 10.1387/ijdb.082680jm connected to a common excretory duct (the Wolffian duct, WD). At this stage, they form a primitive kidney called pronephros which is not functional. This transitory organ can only be observed in vertebrate embryos and agnathe larvae (Saxen and Sariola 1987;Bouchard et al. 2002). Then, while the pronephros is regressing, the mesonephros develops posteriorly, allowing the WD to grow in the same direction. This intermediary kidney, comprising a Bowman ...

SUMMARYDisruption of mouse Prep1, which codes for a homeodomain transcription factor, leads to embryonic lethality during postimplantation stages. Prep1 -/-embryos stop developing after implantation and before anterior visceral endoderm (AVE) formation. In Prep1 -/-embryos at E6.5 (onset of gastrulation), the AVE is absent and the proliferating extra-embryonic ectoderm and epiblast, marked by Bmp4 and Oct4, respectively, are reduced in size. At E.7.5, Prep1-/-embryos are small and very delayed, showing no evidence of primitive streak or of differentiated embryonic lineages. Bmp4 is expressed residually, while the reduced number of Oct4-positive cells is constant up to E8.5. At E6.5, Prep1 -/-embryos retain a normal mitotic index but show a major increase in cleaved caspase 3 and TUNEL staining, indicating apoptosis. Therefore, the mouse embryo requires Prep1 when undergoing maximal expansion in cell number. Indeed, the phenotype is partially rescued in a p53

Familial Mediterranean fever (FMF) is the most frequent hereditary systemic autoinflammatory syndrome. FMF is usually caused by biallelic mutations in the MEFV gene, encoding Pyrin. Conclusive genetic evidence lacks for about 30% of patients diagnosed with clinical FMF. Pyrin is an inflammasome sensor maintained inactive by two kinases (PKN1/2). The consequences of MEFV mutations on inflammasome activation are still poorly understood. Here, we demonstrate that PKC superfamily inhibitors trigger inflammasome activation in monocytes from FMF patients while they trigger a delayed apoptosis in monocytes from healthy donors. The expression of the pathogenic p.M694V MEFV allele is necessary and sufficient for PKC inhibitors (or mutations precluding Pyrin phosphorylation) to trigger caspase‐1‐ and gasdermin D‐mediated pyroptosis. In line with colchicine efficacy in patients, colchicine fully blocks this response in FMF patients’ monocytes. These results indicate that Pyrin inflammasome activation is solely controlled by Pyrin (de)phosphorylation in FMF patients while a second control mechanism restricts its activation in healthy donors/non‐FMF patients. This study paves the way toward a functional characterization of MEFV variants and a functional test to diagnose FMF.

MYBBP1A is a predominantly nucleolar transcriptional regulator involved in rDNA synthesis and p53 activation via acetylation. However little further information is available as to its function. Here we report that MYBBP1A is developmentally essential in the mouse prior to blastocyst formation. In cell culture, down-regulation of MYBBP1A decreases the growth rate of wild type mouse embryonic stem cells, mouse embryo fibroblasts (MEFs) and of human HeLa cells, where it also promotes apoptosis. HeLa cells either arrest at G2/M or undergo delayed and anomalous mitosis. At mitosis, MYBBP1A is localized to a parachromosomal region and gene-expression profiling shows that its down-regulation affects genes controlling chromosomal segregation and cell cycle. However, MYBBP1A down-regulation increases the growth rate of the immortalized NIH3T3 cells. Such Mybbp1a down-regulated NIH3T3 cells are more susceptible to Ras-induced transformation and cause more potent Ras-driven tumors. We conclude that MYBBP1A is an essential gene with novel roles at the pre-mitotic level and potential tumor suppressor activity.

Contrary to the NLRP3 mutations described in cryopyrin-associated periodic syndrome, FMF-associated MEFV mutations do not lead to a constitutive activation of Pyrin. Rather, FMF-associated mutations are hypermorphic mutations that specifically decrease the activation threshold of the Pyrin inflammasome without affecting other canonical inflammasomes.

The Prep1 (Pknox1) homeodomain transcription factor is essential at multiple stages of embryo development. In the E11.5 embryo trunk, we previously estimated that Prep1 binds about 3,300 genomic sites at a highly specific decameric consensus sequence, mainly governing basal cellular functions. We now show that in embryonic stem (ES) cells Prep1 binding pattern only partly overlaps that of the embryo trunk, with about 2,000 novel sites. Moreover, in ES cells Prep1 still binds mostly to promoters, as in total embryo trunk but, among the peaks bound exclusively in ES cells, the percentage of enhancers was three-fold higher. RNA-seq identifies about 1800 genes down-regulated in Prep1 -/- ES cells which belong to gene ontology categories not enriched in the E11.5 Prep1i/i differentiated embryo, including in particular essential components of the Wnt and Fgf pathways. These data agree with aberrant Wnt and Fgf expression levels in the Prep1 -/- ES cells with a deficient embryoid bodies (EBs) formation and differentiation. Re-establishment of the Prep1 level rescues the phenotype.