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S Minucci

Publications and source records attributed to S Minucci.

At least 37 records · Page 2Linked to original sources
PubMed2001

Oligomerization of ETO is obligatory for corepressor interaction.

Nearly 40% of cases of acute myelogenous leukemia (AML) of the M2 subtype are due to a chromosomal translocation that combines a sequence-specific DNA binding protein, AML1, with a potent transcriptional repressor, ETO. ETO interacts with nuclear receptor corepressors SMRT and N-CoR, which recruit histone deacetylase to the AML1-ETO oncoprotein. SMRT-N-CoR interaction requires each of two zinc fingers contained in C-terminal Nervy homology region 4 (NHR4) of ETO. However, here we show that polypeptides containing NHR4 are insufficient for interaction with SMRT. NHR2 is also required for SMRT interaction and repression by ETO, as well as for inhibition of hematopoietic differentiation by AML1-ETO. NHR2 mediates oligomerization of ETO as well as AML1-ETO. Fusion of NHR4 polypeptide to a heterologous dimerization domain allows strong interaction with SMRT in vitro. These data support a model in which NHR2 and NHR4 have complementary functions in repression by ETO. NHR2 functions as an oligomerization domain bringing together NHR4 polypeptides that together form the surface required for high-affinity interaction with corepressors. As nuclear receptors also interact with corepressors as dimers, oligomerization may be a common mechanism regulating corepressor interactions.

Binding Sites↗
PubMed2001

Isolation and characterization of a novel member of the relaxin/insulin family from the testis of the frog Rana esculenta.

A complementary DNA (cDNA) encoding a frog relaxin/insulin member family (fRLX) from testis cDNA library was isolated and characterized. The fRLX cDNA predicted a 155-amino acid protein with a low homology to mammalian RLF and relaxin. Northern blot analysis revealed a single transcript expressed in the interstitial compartment, RT-PCR, evidenced that fRLX is expressed at low levels in the oviduct and ovary too. The predicted mature fRLX protein, composed of the signal peptide, B, C, and A domains, has conserved amino acid sequences in the characteristic functional domains. A different expression of the transcript was found during the frog reproductive cycle, with a peak in Spring. After administration of ethane dimethane sulfonate, by in situ hybridization, fRLX messenger RNA disappeared from the interstitial compartment and reappeared again at the time of generating of a new population of Leydig cells (LC), strongly indicating that LC are the interstitial cell type expressing fRLX. Preliminary results obtained by in situ hybridization, performed on testis of hypophysectomized frogs evidenced a pituitary control of fRLX expression. This study is the first cloning of a relaxin/insulin family member in a nonmammalian vertebrate. In addition, because fRLX expression changes during the annual cycle suggesting its involvement in spermatogenesis, fRLX may be considered a new marker for the study of spermatogenesis in the Rana esculenta.

Amino Acid Sequence↗
PubMed2001

[Percutaneous treatment of varicocele. 13-year experience with the transbrachial approach].

PURPOSE: To report our experience using the transbrachial approach, which is easily accepted by the patient, in the treatment of varicocele. MATERIAL AND METHODS: Between January 1986 and December 1998, 1490 patients with clinical or subclinical varicocele, but with seminal fluid alterations, underwent spermatic phlebography using the transbrachial approach. Since 1991 the procedure has also been adopted at the Unit of Pediatric Surgery of our hospital, which proposes it as a first choice treatment in adolescents with varicocele. The procedure consists in accessing the basilic vein at the elbow level percutaneously and using a hydrophile guidewire and multipurpose angiographic catheter to reach and catheterise the spermatic vein responsible for the varicocele. During the first years, we used sclerotherapy alone; subsequently, if the varicocele recurred or if the reflux was refractory to sclerotherapy or if the veins were large we adopted vein embolisation. Follow-up was one year and consisted of testicular ultrasound, Doppler flowmetry and/or color Doppler ultrasound at one, six and twelve months after the procedure. Patients were considered restored if they were free of symptoms, showed no venous reflux and/or had normal seminal fluid parameters and improved if they were free of symptoms but still presented venous reflux. Varicocele was considered persistent if the procedure failed to produce any beneficial effects, and recurrent if, although absent at the first follow up, it reappeared after the fifth month. RESULTS: We found 1296 (86.9%) cases of left varicocele, 25 of right varicocele and 169 (11.3%) of bilateral varicocele. In all cases, the symptoms disappeared after the percutaneous procedure. Duration of radioscopy was reduced to 3.5'; the procedure lasted 90' for the monolateral varicoceles and 120' for the bilateral forms. 313 diagnostic procedures were performed (20.7%). The procedure could not be completed in 104 patients (6.8%) due to basilic vein spasms, difficulties encountered in catheterizing the spermatic vein and, particularly in pediatric patients, anatomic variations. A total of 1195 (79.2%) procedures were completed: sclerotherapy alone in 642 patients and sclerotherapy followed by scleroembolisation in 527. Sclerotherapy alone was sufficient to restore 524 patients (86.6%), while 384 (78.5%) required scleroembolization. A small number of patients underwent scleroembolization alone, which brings the success rate for the two procedures to 82% and 84%, respectively. No serious side-effects were noted. DISCUSSION: The transbrachial approach in spermatic phlebography has proved to be a safe and effective technique for the treatment of both monolateral and bilateral varicocele. Furthermore, the procedure is well accepted by patients and can be performed in a day-care setting. In some cases, we only obtained partial results because of the large caliber of the spermatic vein; in other cases, we were unable to complete the procedure due to anatomic variations or to the spasm of the basilic vein. CONCLUSION: The safety and effectiveness of this procedure make it a valid alternative to traditional surgery, that should be considered as a possible first-choice treatment for varicocele in adolescents.

Adolescent↗
PubMed2000

Activation of Rac1 and the p38 mitogen-activated protein kinase pathway in response to all-trans-retinoic acid.

Several signaling pathways are activated by all-trans-retinoic acid (RA) to mediate induction of differentiation and apoptosis of malignant cells. In the present study we provide evidence that the p38 MAP kinase pathway is activated in a RA-dependent manner in the NB-4, acute pro-myelocytic leukemia, and the MCF-7, breast carcinoma, cell lines. RA treatment of cells induces a time- and dose-dependent phosphorylation of p38, and such phosphorylation results in activation of its catalytic domain. p38 activation is not inducible by RA in a variant NB-4 cell line, NB-4.007/6, which is resistant to the effects of RA, suggesting a role for this pathway in the induction of RA responses. Our data also demonstrate that the small G-protein Rac1 is activated by RA and functions as an upstream regulator of p38 activation, whereas the MAPKAPK-2 serine kinase is a downstream effector for the RA-activated p38. To obtain information on the functional role of the Rac1/p38/MAPKAPK-2 pathway in RA signaling, the effects of pharmacological inhibition of p38 on RA-induced gene transcription and cell differentiation were determined. Our results indicate that treatment of cells with the SB203580 inhibitor does not inhibit RA-dependent gene transcription via retinoic acid response elements or induction of Stat1 protein expression. However, treatment with SB203580 or SB202190 strongly enhances RA-dependent induction of cell differentiation and RA-regulated growth inhibitory responses. Altogether, our findings demonstrate that the Rac1/p38 MAP kinase pathway is activated in a RA-dependent manner and exhibits negative regulatory effects on the induction of differentiation.

Cell Differentiation↗
PubMed2000

Effects of multiple injections of ethane 1,2-dimethane sulphonate (EDS) on the frog, Rana esculenta, testicular activity.

Ethane 1,2-dimethane sulphonate (EDS) is an alkylating agent, which has a selective cytotoxic effect on Leydig cells in some mammalian species. Similarly, in the frog, Rana esculenta, Leydig cells are destroyed after a single EDS injection and regenerate after 28 days. Regeneration of Leydig cells in frogs appears to be independent of the pituitary. The present experiments in R. esculenta were carried out: a) to investigate Leydig cell responsiveness to gonadotropin stimulation during 58 days after a single EDS injection; and b) to assess whether four consecutive EDS injections induce additional effects on the testicular cell population. Our results show that androgen stimulation after gonadotropin injections is restored after 44 days from a single EDS injection. Since the interstitial compartment appears to be normal at least 28 days after EDS treatment, it is likely that new Leydig cells lack gonadotropin receptors. With respect to multiple-EDS injections, Leydig cells completely disappear in several areas and the adjacent germinal compartment is disorganised. In some cases damaged germinal compartment is still surrounded by intact Leydig cells. Surprisingly, testicular and plasma androgens strongly increase in EDS-treated animals. Therefore, Sertoli cells may produce substances inhibiting androgen production in Leydig cells. J. Exp. Zool. 287:384-393, 2000.

Animals↗
PubMed2000

PML regulates p53 acetylation and premature senescence induced by oncogenic Ras.

The tumour suppressor p53 induces cellular senescence in response to oncogenic signals. p53 activity is modulated by protein stability and post-translational modification, including phosphorylation and acetylation. The mechanism of p53 activation by oncogenes remains largely unknown. Here we report that the tumour suppressor PML regulates the p53 response to oncogenic signals. We found that oncogenic Ras upregulates PML expression, and overexpression of PML induces senescence in a p53-dependent manner. p53 is acetylated at lysine 382 upon Ras expression, an event that is essential for its biological function. Ras induces re-localization of p53 and the CBP acetyltransferase within the PML nuclear bodies and induces the formation of a trimeric p53-PML-CBP complex. Lastly, Ras-induced p53 acetylation, p53-CBP complex stabilization and senescence are lost in PML-/- fibroblasts. Our data establish a link between PML and p53 and indicate that integrity of the PML bodies is required for p53 acetylation and senescence upon oncogene expression.

Acetylation↗
PubMed2000

Morphology of the Harderian gland of the Gecko, Tarentola mauritanica.

The Harderian gland of the gecko, Tarentola mauritanica, was studied at the histological, histochemical, and ultrastructural levels. It is a nonlobate compound acinar gland surrounded by a thin capsule of connective tissue. Numerous connective tissue-type mast cells, ultrastructurally similar to those described in other higher vertebrates, were identified in the interstitial tissue between the acini. Pyramidal or columnar-shaped secretory glandular cells were observed in the acini. In the glandular cells, two types of structures could be distinguished on the basis of their high or low electron density. Lipid droplets were found in the cytoplasm of the Harderian gland of both sexes. Histochemical tests showed that the Harderian gland of the gecko is a seromucous gland. The secretion is essentially merocrine, although an apocrine type of secretion is sometimes observed.

Animals↗
PubMed2000

Oligomerization of RAR and AML1 transcription factors as a novel mechanism of oncogenic activation.

RAR and AML1 transcription factors are found in leukemias as fusion proteins with PML and ETO, respectively. Association of PML-RAR and AML1-ETO with the nuclear corepressor (N-CoR)/histone deacetylase (HDAC) complex is required to block hematopoietic differentiation. We show that PML-RAR and AML1-ETO exist in vivo within high molecular weight (HMW) nuclear complexes, reflecting their oligomeric state. Oligomerization requires PML or ETO coiled-coil regions and is responsible for abnormal recruitment of N-CoR, transcriptional repression, and impaired differentiation of primary hematopoietic precursors. Fusion of RAR to a heterologous oligomerization domain recapitulated the properties of PML-RAR, indicating that oligomerization per se is sufficient to achieve transforming potential. These results show that oligomerization of a transcription factor, imposing an altered interaction with transcriptional coregulators, represents a novel mechanism of oncogenic activation.

Cell Transformation, Neoplastic↗
PubMed2000

Effects of sex steroid hormones and their antagonists on mast cell number in the testis of the frog, Rana esculenta.

This study confirms our previous data on the effects of sex hormones on mast cell number (MCN) in the testis of frog Rana esculenta. After 15 days of treatment with oestradiol (E2) MCN strongly increases, while testosterone has no effect. After 30 days only a small increase in MCN is observed. These differences could be due to the non-physiological effect of E2 over a prolonged period. We also confirmed a massive increase in MCN after 15 or 30 days of treatment with cyproterone acetate (CPA). This increase in MCN is also observed after administration of CPA with tamoxifen. Ultrastructural analysis of testis shows empty spaces with degenerating Leydig cells in the interstitial compartment and numerous germinal cells completely degenerated, probably apoptotic, in the adjacent germinal compartment. The same effects were observed in testes after treatment with only CPA. Chronic E2 treatment provokes an increase in MCN on day 2. From day 4 to 12 of the treatment, MCN decreases dramatically and many germinal tubules appear strongly disorganised. In conclusion, the present results confirm that E2 treatment induces changes in MCN and chronic E2 treatment modifies the morphology of the frog testes. In addition, blocking androgen receptors with CPA, alone or in combination with tamoxifen, causes a significant increase in MCN, confirming the involvement of androgens in mast cell proliferation and/or differentiation.

Androgen Antagonists↗
PubMed1999

Constitutive degradation of PML/RARalpha through the proteasome pathway mediates retinoic acid resistance.

PML/RARalpha is the leukemogenetic protein of acute promyelocytic leukemia (APL). Treatment with retinoic acid (RA) induces degradation of PML/RARalpha, differentiation of leukaemic blasts, and disease remission. However, RA resistance arises during RA treatment of APL patients. To investigate the phenomenon of RA resistance in APL, we generated RA-resistant sublines from APL-derived NB4 cells. The NB4.007/6 RA-resistant subline does not express the PML/RARalpha protein, although its mRNA is detectable at levels comparable to those of the parental cell line. In vitro degradation assays showed that the half-life of PML/RARalpha is less than 30 minutes in NB4.007/6 and longer than 3 hours in NB4. Treatment of NB4.007/6 cells with the proteasome inhibitors LLnL and lactacystin partially restored PML/RARalpha protein expression and resulted in a partial release of the RA-resistant phenotype. Similarly, forced expression of PML/RARalpha, but not RARalpha, into the NB4/007.6 cells restored sensitivity to RA treatment to levels comparable to those of the NB4 cells. These results indicate that constitutive degradation of PML/RARalpha protein may lead to RA resistance and that PML/RARalpha expression is crucial to convey RA sensitivity to APL cells.

Antineoplastic Agents↗
PubMed1999

Retinoid receptors in health and disease: co-regulators and the chromatin connection.

Retinoid receptors behave as ligand-dependent transcriptional regulators, repressing transcription in the absence of ligand and activating transcription in its presence. The different effects on transcription are carried out through recruitment of co-regulators: unliganded receptors bind corepressors (NCoR and SMRT) that are found within a complex containing histone deacetylase (HDAC) activity, whereas liganded receptors recruit coactivators with histone acetylase activity (HATs). Chromatin remodeling activities have also shown to be required, suggesting a hierarchy of promoter structure modifications in RA target genes carried out by multiple coregulatory complexes. In this review, we examine the experimental evidence for the model just sketched. We focus on recent findings highlighting new molecular details in receptor-coregulator interactions, including the discovery and initial characterisation of novel complexes with multiple chromatin modifying activities. Finally, we look at the role of aberrant recruitment of the NCoRHDAC complex by altered retinoid receptors in the pathogenesis of acute promyelocytic leukemia. These results point to a crucial role for control of transcription factor coregulator interactions in the regulation of cellular processes, and suggest new molecular targets for cancer therapy.

Acetylation↗
PubMed1999

Varicocele: a multidisciplinary approach in children and adolescents.

PURPOSE: To minimize varicocele treatment in children and adolescents a multidisciplinary approach that includes surgery and operative radiology has been used at our institution since 1991. We present our results during this 7-year period. MATERIALS AND METHODS: From January 1991 to December 1997 we examined 477 patients 4 years 5 months to 25 years 4 months old (mean age 13 years 3 months) with varicocele, of whom 367 (396 varicoceles) required treatment. Percutaneous sclero-embolization was suggested as the primary treatment of choice in all cases, while surgery was reserved for select cases. A total of 366 cases followed at least 6 months (mean 1 year) were entered into this study. RESULTS: Only 7.1% of the patients or families preferred surgery. In 47 patients sclero-embolization was not possible due to technical problems or vascular anomalies. Sclero-embolization was successful in 79.4% of 277 patients, and retroperitoneal ligation was successful in 88.7% of 124. Since 1995 ligation of the whole spermatic bundle above the vas deferens has been preferred, and only 1 recurrence has been observed in 60 cases. CONCLUSIONS: Percutaneous sclero-embolization is a minimally invasive treatment of varicocele that is feasible in children and adolescents. Most patients prefer this therapy, although it is not as safe as surgery. When open surgery is required, complete ligation of the whole vascular pedicle above the vas deferens offers excellent success.

Adolescent↗
PubMed1999

c-fos activity in Rana esculenta testis: seasonal and estradiol-induced changes.

Estradiol-17beta (E2) is suspected to exert a role in the regulation of testicular activity. Using a nonmammalian vertebrate model (the frog, Rana esculenta), we have investigated whether c-fos activity is detectable in the testis during the annual sexual cycle and whether E2 exerts a regulatory role on spermatogenesis through fos activity. FOS protein is available in testicular nuclear extracts (about 60 kDa) and, surprisingly, also in cytosolic extracts (about 60, 80, and 100 kDa). Estradiol induces primary spermatogonia (ISPG) proliferation [this effect is counteracted by antiestrogens (Tamoxifen and ICI 182-780)] and FOS appearance in testicular cytosolic extracts as well as c-fos transcription. Also, this effect is counteracted by ICI 182-780. Interestingly, the number of FOS immunopositive nuclei of ISPG strongly increases after E2 treatment, whereas a great increase of immunopositivity in the cytoplasm of ISPG is observed with the contemporaneous treatment with antiestrogens. In conclusion, our results demonstrate that E2 induces ISPG multiplication in the frog, R. esculenta, and, for the first time in a vertebrate species, that it triggers c-fos activity in the testis. Moreover, E2 may be involved in mechanisms related to FOS transport in the nucleus of ISPG to induce the mitotic activity.

Animals↗
PubMed1998

The histone acetylase PCAF is a nuclear receptor coactivator.

Whereas the histone acetylase PCAF has been suggested to be part of a coactivator complex mediating transcriptional activation by the nuclear hormone receptors, the physical and functional interactions between nuclear receptors and PCAF have remained unclear. Our efforts to clarify these relationships have revealed two novel properties of nuclear receptors. First, we demonstrate that the RXR/RAR heterodimer directly recruits PCAF from mammalian cell extracts in a ligand-dependent manner and that increased expression of PCAF leads to enhanced retinoid-responsive transcription. Second, we demonstrate that, in vitro, PCAF directly associates with the DNA-binding domain of nuclear receptors, independently of p300/CBP binding, therefore defining a novel cofactor interaction surface. Furthermore, our results show that dissociation of corepressors enables ligand-dependent PCAF binding to the receptors. This observation illuminates how a ligand-dependent receptor function can be propagated to regions outside the ligand-binding domain itself. On the basis of these observations, we suggest that PCAF may play a more central role in nuclear receptor function than previously anticipated.

3T3 Cells↗
PubMed1998

Fusion proteins of the retinoic acid receptor-alpha recruit histone deacetylase in promyelocytic leukaemia.

The transforming proteins of acute promyelocytic leukaemias (APL) are fusions of the promyelocytic leukaemia (PML) and the promyelocytic leukaemia zinc-finger (PLZF) proteins with retinoic acid receptor-alpha (RARalpha). These proteins retain the RARalpha DNA- and retinoic acid (RA)-binding domains, and their ability to block haematopoietic differentiation depends on the RARalpha DNA-binding domain. Thus RA-target genes are downstream effectors. However, treatment with RA induces differentiation of leukaemic blast cells and disease remission in PML-RARalpha APLs, whereas PLZF-RARa APLs are resistant to RA. Transcriptional regulation by RARs involves modifications of chromatin by histone deacetylases, which are recruited to RA-target genes by nuclear co-repressors. Here we show that both PML-RARalpha and PLZF-RARalpha fusion proteins recruit the nuclear co-repressor (N-CoR)-histone deacetylase complex through the RARalpha CoR box. PLZF-RARalpha contains a second, RA-resistant binding site in the PLZF amino-terminal region. High doses of RA release histone deacetylase activity from PML-RARalpha, but not from PLZF-RARalpha. Mutation of the N-CoR binding site abolishes the ability of PML-RARalpha to block differentiation, whereas inhibition of histone deacetylase activity switches the transcriptional and biological effects of PLZF-RARalpha from being an inhibitor to an activator of the RA signalling pathway. Therefore, recruitment of histone deacetylase is crucial to the transforming potential of APL fusion proteins, and the different effects of RA on the stability of the PML-RARalpha and PLZF-RARalpha co-repressor complexes determines the differential response of APLs to RA.

Binding Sites↗
PubMed1998

In situ characterization of mast cells in the frog Rana esculenta.

The number, distribution, and ultrastructural characteristics of mast cells were assessed in the tongue, heart, and kidney of the frog Rana esculenta. The density of tongue mast cells (253+/-45 mast cells/mm2) was significantly higher than that of the heart (5.3+/-0. 4/mm2) and kidney (15.3+/-1.4 /mm2). A striking feature of this study was the remarkable association of frog mast cells to nerves. The ultrastructural study of the mast cell/nerve association demonstrated that mast cells were closely apposed to or even embedded in nerves. Mast cells were also physically associated with melanocytes even in the heart. Mast cells were Alcian blue+/safranin+ in the tongue and in the peritoneum, whereas in the heart and in the kidney they were Alcian blue-/safranin+. The mast cells in the lamina propria of the gastrointestinal tract were Alcian blue+/safranin-. The cytoplasm of frog mast cells was packed with numerous heterogeneous, membrane-bound granules. The ultrastructure of these cytoplasmic granules was unique, being totally unlike any other previously described granules in other animal species as well as in man. The histamine content/frog mast cell ( approximately 0.1 pg/cell) was approximately 30 times lower than that of human mast cells isolated from different tissues ( approximately 3 pg/cell). A monoclonal anti-histamine antibody was used to confirm the ultrastructural localization of histamine in secretory granules in frog mast cells.

Animals↗
PubMed1998

TSH and thyroid hormones induce the release of secretory granules in the harderian gland of hypophysectomized frogs, (Rana esculenta): morphological observations.

The secretory activity of the harderian gland (hg) in the frog Rana esculenta is influenced by pituitary and thyroid hormones. Administration of thyroid stimulating hormone (TSH), T3 and T4 to hypophysectomized male and female frogs, affects the release of secretory granules in the lumina of glandular acini. In particular, treatment with T3 radically modified morphological parameters (height and area of acinar lumina of the glandular cells); T4 or TSH had less effect. Administration of thiouracil counteracted TSH effect, restoring the secretory content of the glandular cells. Ultrastructural observations confirmed these results. Our data suggest the existence of a thyroid-hg interaction and that thyroid hormones may be involved in the mechanism of release of mature secretory granules in the hg of the frog, Rana esculenta.

Animals↗