Biomedical subjects

Luca Fusi

Publications and source records attributed to Luca Fusi.

8 recordsLinked to original sources

PubMed2006

Regulation of the SUMO pathway sensitizes differentiating human endometrial stromal cells to progesterone.

cAMP is required for differentiation of human endometrial stromal cells (HESCs) into decidual cells in response to progesterone, although the underlying mechanism is not well understood. We now demonstrate that cAMP signaling attenuates ligand-dependent sumoylation of the progesterone receptor (PR) in HESCs. In fact, decidualization is associated with global hyposumoylation and redistribution of small ubiquitin-like modifier (SUMO)-1 conjugates into distinct nuclear foci. This altered pattern of global sumoylation was not attributable to impaired maturation of SUMO-1 precursor or altered expression of E1 (SAE1/SEA2) or E2 (Ubc9) enzymes but coincided with profound changes in the expression of E3 ligases and SUMO-specific proteases. Down-regulation of several members of the protein inhibitors of activated STAT (PIAS) family upon decidualization pointed toward a role of these E3 ligases in PR sumoylation. We demonstrate that PIAS1 interacts with the PR and serves as its E3 SUMO ligase upon activation of the receptor. Furthermore, we show that silencing of PIAS1 not only enhances PR-dependent transcription but also induces expression of prolactin, a decidual marker gene, in progestin-treated HESCs without the need of simultaneous activation of the cAMP pathway. Our findings demonstrate how dynamic changes in the SUMO pathway mediated by cAMP signaling determine the endometrial response to progesterone.

Cell Differentiation↗

PubMed2006

Catalytic activity of hammerhead ribozymes in a clay mineral environment: implications for the RNA world.

The hypothesized RNA-based world would have required the presence of a protected environment in which RNA, or an RNA-like molecule, could originate and express its biological activity. Recent studies have indicated that RNA molecules adsorbed/bound on clay minerals are able to persist in the presence of degrading agents, to interact with surrounding molecules, and to transmit the information contained in their nucleotide sequences. In this study, we assessed the ability of RNA molecules with catalytic activity to perform a specific reaction in a mineral environment. For this purpose, we investigated the self-cleavage reaction of the hammerhead ribozyme of the Avocado Sun Blotch Viroid (ASBVd), both in the monomeric and in dimeric forms. The monomeric transcript was tightly bound on the clay mineral montmorillonite to form a stable complex, while the behaviour of the dimeric transcript was studied in the presence of the clay particles in the reaction mixture. The results indicated that the hammerhead ribozyme was still active when the monomeric transcript was adsorbed on the clay surface, even though its efficiency was reduced to about 20% of that in solution. Moreover, the self-cleavage of clay-adsorbed molecule was significantly enhanced ( approximately four times) by the presence of the 5' reaction product. The self-cleavage reaction of the dimeric transcript in the presence of montmorillonite indicated that the mineral particles protected the RNA molecules against aspecific degradation and increased the rate of cleavage kinetics by about one order of magnitude. These findings corroborate the hypothesis that clay-rich environments would have been a good habitat in which RNA or RNA-like molecules could originate, accumulate and undergo Darwinian evolutionary processes, leading to the first living cells on Earth.

Adsorption↗

PubMed2006

Differential expression of FOXO1 and FOXO3a confers resistance to oxidative cell death upon endometrial decidualization.

The integrity of the feto-maternal interface is critical for survival of the conceptus. This interface, consisting of the maternal decidua and the invading placental trophoblast, is exposed to profound changes in oxygen tension during pregnancy. We demonstrate that human endometrial stromal cells become extraordinarily resistant to oxidative stress-induced apoptosis upon decidualization in response to cAMP and progesterone signaling. This differentiation process is associated with the induction of the forkhead transcription factor FOXO1, which in turn increases the expression of the mitochondrial antioxidant manganese superoxide dismutase. However, silencing of FOXO1 did not increase the susceptibility of decidualized cells to oxidative cell death. Comparative analysis demonstrated that hydrogen peroxide, a source of free radicals, strongly induces FOXO3a mRNA and protein expression in undifferentiated human endometrial stromal cells but not in decidualized cells. Expression of a constitutively active FOXO3a mutant elicited apoptosis in decidualized cells. Furthermore, silencing of endogenous FOXO3a in undifferentiated cells abrogated apoptosis induced by hydrogen peroxide. These results suggest that the induction of FOXO1 may enhance the ability of decidualized cells to prevent oxidative damage while the simultaneous repression of FOXO3a expression disables the signaling pathway responsible for oxidative cell death. The differential regulation of FOXO expression provides the decidua with a robust system capable of coping with prolonged episodes of oxidative stress during pregnancy.

Apoptosis↗

PubMed2006

The uterine junctional zone.

Magnetic resonance imaging has revealed that the endometrio-myometrial interface constitutes a distinct, hormone-dependent uterine compartment termed the junctional zone. In the non-pregnant uterus, highly specialized contraction waves originate exclusively from the junctional zone and participate in the regulation of diverse reproductive events, such as sperm transport, embryo implantation, and menstrual shedding. Conversely, growing evidence suggests that disruption of the normal endometrio-myometrial interface plays an integral role in diverse reproductive disorders. This chapter reviews our current understanding of the mechanisms that govern the cyclic changes in the uterine junctional zone and summarizes the evidence implicating the endometrio-myometrial interface in normal uterine physiology and pathological processes.

Endometriosis↗

PubMed2005

Progestins regulate the expression and activity of the forkhead transcription factor FOXO1 in differentiating human endometrium.

Menstruation, or cyclic shedding of nonpregnant endometrial tissue with associated bleeding, occurs only in humans and a few other species. This breakdown of the endometrium in response to falling ovarian progesterone levels is a complex process, characterized by local leukocyte infiltration, expression and activation of matrix metalloproteinases, and apoptosis. Spontaneous decidualization (differentiation) of the stromal compartment precedes the cyclic shedding of the endometrium in various menstruating species but the mechanisms that link these processes are not understood. In this study, we identified FOXO1 as a key transcription factor responsible for mediating apoptosis of decidualized human endometrial stromal cells (HESCs) in response to progesterone withdrawal. We demonstrate that medroxyprogesterone acetate (MPA, a synthetic progestin) enhances the expression of FOXO1 in differentiating HESCs while simultaneously inducing cytoplasmic retention and inactivation of FOXO1. Withdrawal of MPA from decidualized HESCs results in rapid nuclear accumulation of FOXO1, increased BIM expression, a proapoptotic FOXO1 target gene, and cell death. Conversely, silencing of FOXO1 expression completely abolishes cell death induced by MPA withdrawal. In summary, the observation that differentiating HESCs become dependent on progesterone signaling for survival through induction and reversible inactivation of FOXO1 suggests a novel mechanism that links decidualization of the endometrium to menstruation.

Active Transport, Cell Nucleus↗

PubMed2004

Convergence of interferon-gamma and progesterone signaling pathways in human endometrium: role of PIASy (protein inhibitor of activated signal transducer and activator of transcription-y).

All cardinal events during the reproductive cycle, including ovulation, implantation, and menstruation, are characterized by a profound tissue remodeling and an associated local inflammatory response. The ovarian hormone progesterone is a key modulator of inflammatory signals in reproductive tissues, but the underlying mechanisms are not well understood. In this study, we report that differentiating human endometrial stromal cells (ESCs) acquire resistance to interferon-gamma (IFNgamma)-dependent signal transducers and activators of transcription (STAT) 1 signaling, although phosphorylation, nuclear translocation, and binding of STAT1 to DNA, are unaffected. These observations prompted an investigation into the role of nuclear repressors of STAT1 signaling. We demonstrate that protein inhibitor of activated STAT-y is complexed to the progesterone receptor (PR) in human ESCs and that its ability to repress STAT1 signaling is dependent upon activation of PR in response to hormone binding. Conversely, IFNgamma and protein inhibitor of activated STAT-y synergistically inhibited PR-dependent transcription, demonstrating that the progesterone and IFNgamma signaling pathways engage in reciprocal transcriptional antagonism in human endometrium.

Cell Differentiation↗

PubMed2002

Aromatase P450 messenger RNA expression in eutopic endometrium is not a specific marker for pelvic endometriosis.

OBJECTIVE: To determine whether expression of aromatase P450 mRNA in eutopic endometrium is predictive of the presence of pelvic endometriosis. DESIGN: A prospective, multicenter, observational study. SETTING: Four tertiary centers for reproductive medicine. PATIENT(S): Sixty subjects of reproductive age undergoing laparoscopy for subfertility exploration, pain assessment, or sterilization. INTERVENTION(S): Endometrial biopsy at time of laparoscopy. MAIN OUTCOME MEASURE(S): The expression of aromatase P450 mRNA in endometrial specimens was determined by single-tube reverse transcription-polymerase chain reaction (RT-PCR). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA was amplified in parallel to exclude amplification failure. RESULT(S): The RT-PCR amplification was successful in 56 of the 60 biopsies (93%). Pelvic endometriosis was diagnosed in 34 patients (61%) and was strongly associated with aromatase P450 mRNA expression in eutopic endometrium. As a diagnostic marker for endometriosis, aromatase P450 mRNA expression yielded a sensitivity of 82%, a specificity of 59%, a positive predictive value of 76%, and a negative predictive value of 67%. If additional uterine pathology was taken in account, the sensitivity increased to 84%, the specificity to 72%, the positive predictive value to 87%, but the negative predictive value remained unchanged (67%). CONCLUSION(S): Although endometrial aromatase P450 gene expression is highly predictive of the presence of pelvic disease, the relative high incidence of false-negative results and lack of specificity is likely to impair clinical application.

Adult↗

PubMed2002

Change in brain size during and after pregnancy: study in healthy women and women with preeclampsia.

BACKGROUND AND PURPOSE: Qualitative decreases in maternal brain size have been observed late in pregnancy. The aim of this study was to quantitatively evaluate changes to the maternal brain during and after healthy pregnancy and to compare these changes with those observed in cases of preeclampsia. METHODS: Three-dimensional T1-weighted MR volume images were obtained in nine healthy participants before and after delivery. Additional images were obtained in some of these participants before pregnancy, during pregnancy, and within 52 weeks after delivery. Five women with preeclampsia were examined before delivery and 6 weeks after delivery. Three of these patients were examined within 52 weeks after delivery. Images were registered, and both brain and ventricular volumes were calculated by using a semiautomated computer program. RESULTS: Both the healthy and preeclamptic groups had a reduction in brain size during pregnancy that was maximal at term and that reversed by 6 months after delivery. The ventricular size showed a corresponding increase in size during pregnancy and a decrease in size after delivery. In the preeclamptic patients, brain size was significantly smaller (P =.05) than in healthy participants, both before and after delivery. CONCLUSION: The brain decreases in size during pregnancy and increases in size after delivery. The changes follow a consistent time course in each woman. The mechanism and physiologic importance of these findings are speculative at the present time.

Adult↗