Clusterin is a usually secreted glycoprotein with chaperone properties. Recently, it has been suggested that clusterin isoforms reside in the nuclear and cytosolic compartments of human cell types, where they can influence various cellular programs including DNA repair, transcription and apoptosis. Several mechanisms have been proposed to explain this atypical location, including alternative transcription initiation and alternative splicing. However, none of these have been unequivocally established as occurring in live cells. Here we provide direct experimental evidence that in live intact cells, under certain stress conditions, clusterin can evade the secretion pathway and reach the cytosol. This was demonstrated using several complementary approaches. Flow cytometry and selective permeabilization of U251 cell membranes with digitonin allowed detection of cytosolic clusterin in stressed U251 cells. In addition, a stringent enzymatic assay reliant upon the exclusively cytosolic deubiquitinase enzymes confirmed that clusterin synthesized with its hydrophobic secretion signal sequence can reach the cytosol of U251 cells. The retrotranslocation of clusterin is likely to occur through a mechanism similar to the endoplasmic reticulum (ER)‐associated protein degradation pathway and involves passage through the Golgi apparatus. We also report that the ER‐associated ubiquitin ligase Hrd1/synoviolin can interact with, and ubiquitinate clusterin. The possible biological functions of these novel behaviours of clusterin are discussed.

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 ...

Sister chromatid cohesion, which depends on cohesin, is essential for the faithful segregation of replicated chromosomes. Here, we report that splicing complex Prp19 is essential for cohesion in both G2 and mitosis, and consequently for the proper progression of the cell through mitosis. Inactivation of splicing factors SF3a120 and U2AF65 induces similar cohesion defects to Prp19 complex inactivation. Our data indicate that these splicing factors are all required for the accumulation of cohesion factor Sororin, by facilitating the proper splicing of its pre-mRNA. Finally, we show that ectopic expression of Sororin corrects defective cohesion caused by Prp19 complex inactivation. We propose that the Prp19 complex and the splicing machinery contribute to the establishment of cohesion by promoting Sororin accumulation during S phase, and are, therefore, essential to the maintenance of genome stability.