Translational regulation in the cellular response to biosynthetic load on the endoplasmic reticulum.
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Animals↗
Biomedical subjects
A Bertolotti
Publications and source records attributed to A Bertolotti.
Increased sensitivity to dextran sodium sulfate colitis in IRE1beta-deficient mice.
The epithelial cells of the gastrointestinal tract are exposed to toxins and infectious agents that can adversely affect protein folding in the endoplasmic reticulum (ER) and cause ER stress. The IRE1 genes are implicated in sensing and responding to ER stress signals. We found that epithelial cells of the gastrointestinal tract express IRE1beta, a specific isoform of IRE1. BiP protein, a marker of ER stress, was elevated in the colonic mucosa of IRE1beta(-/-) mice, and, when exposed to dextran sodium sulfate (DSS) to induce inflammatory bowel disease, mutant mice developed colitis 3-5 days earlier than did wild-type or IRE1beta(+/-) mice. The inflammation marker ICAM-1 was also expressed earlier in the colonic mucosa of DSS-treated IRE1beta(-/-) mice, indicating that the mutation had its impact early in the inflammatory process, before the onset of mucosal ulceration. These findings are consistent with a model whereby perturbations in ER function, which are normally mitigated by the activity of IRE1beta, participate in the development of colitis.
Animals↗
Alterations in an IRE1-RNA complex in the mammalian unfolded protein response.
IRE1 proteins mediate cellular responses to accumulation of malfolded proteins in the endoplasmic reticulum in the yeast and mammalian unfolded protein responses. A sensitive in vivo u.v. crosslinking assay showed that IRE1 proteins are intimately associated with RNA in mammalian cells. The IRE1-associated RNA fragments recovered by this assay were different in stressed and unstressed cells. The amount of RNA associated with IRE1 that could be revealed by end-labeling with T4 kinase was greater in IRE1-containing complexes isolated from stressed cells. Furthermore, the RNA fragments recovered from complexes found in stressed cells were shorter than those from unstressed cells, revealing a dynamic change in the IRE1-RNA complex during the UPR. Formation of the complex between IRE1 and RNA was dependent on both the kinase and endonuclease domains of IRE1, and involved pre-existing RNA species. When viewed in the context of the known importance of Ire1p-HAC1 mRNA interactions to the yeast unfolded protein response, these findings suggest that full-length mammalian IRE1s also engage RNA molecules as downstream effectors.
Animals↗
[Association between breast and colorectal cancer and polyps. Screening and epidemiological study].
BACKGROUND: Studies regarding the associations between different types of cancer in the same patient are very few and not always come to the same conclusions. Several hypothesis are suggested and particularly genetic and socioeconomical ones seem to offer an interpretation of this issue. Early detection of a second neoplasm allows to improve prognosis and survival. The knowledge of correlations between tumors help to select a population, with a high risk to develop a second cancer, to be included in a screening program. Nowadays thanks to early detection of breast cancer, ten years survival is more than 75%. Women who had breast cancer now live longer and so could have a higher risk to develop a second cancer. METHODS: From September 1998 to September 1999 in our Department 71 patients operated for breast cancer, underwent screening colonscopy. No patients refused to be included in the study. Mean age was 61 years (range 36-87). Each patient had a clinician interview in order to explain the goals of the study. RESULTS: Results show that among all patients 3 (4.2%) presented a history of colon cancer, 18.3% (13 cases) presented large bowel polyps. In 84.60% patients (11 cases) polyps were found not over 40 cm. This study shows that 93% of patients (66 cases) had a relative with cancer history. CONCLUSIONS: Our results compared with those of other authors seem to show an increased risk for breast cancer patients in developing polyps or colon cancer, so we suggest to insert sigmoidoscopy in standard follow-up of breast cancer patients.
Adult↗
Coupling of stress in the ER to activation of JNK protein kinases by transmembrane protein kinase IRE1.
Malfolded proteins in the endoplasmic reticulum (ER) induce cellular stress and activate c-Jun amino-terminal kinases (JNKs or SAPKs). Mammalian homologs of yeast IRE1, which activate chaperone genes in response to ER stress, also activated JNK, and IRE1alpha-/- fibroblasts were impaired in JNK activation by ER stress. The cytoplasmic part of IRE1 bound TRAF2, an adaptor protein that couples plasma membrane receptors to JNK activation. Dominant-negative TRAF2 inhibited activation of JNK by IRE1. Activation of JNK by endogenous signals initiated in the ER proceeds by a pathway similar to that initiated by cell surface receptors in response to extracellular signals.
Animals↗
Perk is essential for translational regulation and cell survival during the unfolded protein response.
Malfolded proteins in the endoplasmic reticulum (ER) inhibit translation initiation. This response is believed to be mediated by increased phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha) and is hypothesized to reduce the work load imposed on the folding machinery during stress. Here we report that mutating the gene encoding the ER stress-activated eIF2alpha kinase PERK abolishes the phosphorylation of eIF2alpha in response to accumulation of malfolded proteins in the ER resulting in abnormally elevated protein synthesis and higher levels of ER stress. Mutant cells are markedly impaired in their ability to survive ER stress and inhibition of protein synthesis by cycloheximide treatment during ER stress ameliorates this impairment. PERK thus plays a major role in the ability of cells to adapt to ER stress.
Adaptation, Physiological↗
Dynamic interaction of BiP and ER stress transducers in the unfolded-protein response.
PERK and IRE1 are type-I transmembrane protein kinases that reside in the endoplasmic reticulum (ER) and transmit stress signals in response to perturbation of protein folding. Here we show that the lumenal domains of these two proteins are functionally interchangeable in mediating an ER stress response and that, in unstressed cells, both lumenal domains form a stable complex with the ER chaperone BiP. Perturbation of protein folding promotes reversible dissociation of BiP from the lumenal domains of PERK and IRE1. Loss of BiP correlates with the formation of high-molecular-mass complexes of activated PERK or IRE1, and overexpression of BiP attenuates their activation. These findings are consistent with a model in which BiP represses signalling through PERK and IRE1 and protein misfolding relieves this repression by effecting the release of BiP from the PERK and IRE1 lumenal domains.
Animals↗
IRE1 and efferent signaling from the endoplasmic reticulum.
Genetic analysis of the cellular adaptation to malfolded proteins in the endoplasmic reticulum (the unfolded protein response - UPR) has revealed a novel signaling pathway initiated by activation of IRE1, an ER-resident protein kinase and endonuclease. In yeast, Ire1p activates gene expression by promoting a non-conventional splicing event that converts the mRNA encoding the Hac1p transcription factor from an inefficiently translated inactive mRNA to an actively translated one. Hac1p binds to the promoters of genes encoding chaperones and other targets of the UPR and activates them. Recently, mammalian IRE1 homologues have been identified and their response to ER stress is regulated by binding to the ER chaperone BiP. The mechanisms by which mammalian IRE1 activates gene expression have not been completely characterized and mammalian HAC1 homologues have not been identified. Surprisingly, mammalian IRE1s are able to activate both JUN N-terminal kinases and an alternative ER-stress signaling pathway mediated by the transcription factor ATF6. This indicates that the mammalian UPR is more complex than that found in yeast.
Endoplasmic Reticulum↗
The N-terminal domain of human TAFII68 displays transactivation and oncogenic properties.
In Ewing tumor, the (11;22) chromosomal translocation produces a chimeric molecule composed of the amino-terminal domain of EWS fused to the carboxyl-terminal DNA-binding domain of FLI-1. Previously, we have identified a novel protein TAFII68, which is highly similar to EWS and another closely related protein TLS (also called FUS). We demonstrate that the N-terminus of TAFII68 efficiently stimulates transcription when fused to two different DNA binding domains and that overexpression of TAFII68-FLI-1 chimeras in NIH3T3 cells leads to oncogenic transformation. We have also investigated the molecular mechanisms which could account for the transcriptional activation and the oncogenic transformation potential of the N-termini of TAFII68 and EWS. Thus, we have tested whether the artificial recruitment of components of the preinitiation complex (PIC) or a histone acetyltransferase (HAT) could bypass the requirement for the activation domains of either EWS or TAFII68. Recruitment of individual components of the transcription machinery or the GCN5 HAT is not sufficient to promote activation from FLI-1 responsive genes either in transfection experiments or in oncogenic transformation assays. These results suggest that the TAFII68 or EWS activation domains enhance a step after PIC formation in the transcriptional activation process.
3T3 Cells↗
Valve operations through a minimally invasive approach.
BACKGROUND: We analyzed in-hospital results of 87 patients undergoing minimally invasive valvular operations (right parasternal incision through third and fourth cartilages). METHODS: Age was 21 to 84 years (mean, 56.2 +/- 16); 45 patients (51.7%) were female. Five (5.7%) had a previous valvular operation and 8 (9.2%) had severe left ventricular dysfunction. Valve diseases were as follows: aortic in 35 patients (40.2%), mitral in 44 (50.5%), double in 5 (5.7%), tricuspid regurgitation in 2 (2.2%), and mitral periprosthetic leak in 1 (1.1%). RESULTS: Nineteen mitral repairs (21.9%), 22 replacements (25.3%), 1 leak closure (1.1%), 1 tricuspid repair (1.1%), and 1 replacement (1.1%) were performed. Thirty-one patients (35.7%) underwent aortic replacement, 2 (2.3%) aortic decalcification, 1 (1.1%) subaortic membrane resection, 4 (4.6%) a double-valve procedure, and 5 (5.7%) a single-valve operation combined with myocardial revascularization. In-hospital mortality was 5.7% (5 patients). Univariate analysis was significant for previous operation, New York Heart Association class IV and severe ventricular dysfunction. Multivariate analysis was significant for previous operation and severe ventricular dysfunction. Atrial fibrillation (12.6%) was the most frequent complication. Postoperative stay was 6.5 +/- 6 days. CONCLUSIONS: The minimally invasive approach is a useful technique in valvular surgery. Patients with a previous valvular operation, severe ventricular dysfunction, and New York Heart Association class IV dyspnea have higher in-hospital mortality.
Adult↗
Left anterior descending coronary artery bypass grafting through minimal thoracotomy.
BACKGROUND: In recent years, minimally invasive direct coronary artery bypass grafting has emerged as a valid tool for revascularization in a select group of patients with severe lesions of the left anterior descending coronary artery. Here we report the clinical results using two devices designed by us to facilitate the harvesting of the left internal mammary artery up to its origin and to occlude and stabilize the left anterior descending coronary artery while placing the anastomosis. METHODS: From January 1996 to January 1998, 122 patients underwent minimally invasive direct coronary artery bypass grafting in the Department of Cardiac Surgery, Favaloro Foundation. One hundred twelve patients received a single left internal mammary artery-left anterior descending coronary artery bypass graft, and in 10 patients, an additional bypass graft was performed. RESULTS: Most patients were discharged on day 2 or 3 after the procedure. Three patients (2.5%) had a perioperative myocardial infarction. The overall hospital mortality rate was 3.3% (4 patients). CONCLUSIONS: The combination of team experience, more careful dissection of the left internal mammary artery up to its origin, and use of the stabilizer-occluder and interrupted suture technique for the anastomosis has markedly improved our results.
Adult↗
EWS, but not EWS-FLI-1, is associated with both TFIID and RNA polymerase II: interactions between two members of the TET family, EWS and hTAFII68, and subunits of TFIID and RNA polymerase II complexes.
The t(11;22) chromosomal translocation specifically linked to Ewing sarcoma and primitive neuroectodermal tumor results in a chimeric molecule fusing the amino-terminus-encoding region of the EWS gene to the carboxyl-terminal DNA-binding domain encoded by the FLI-1 gene. As the function of the protein encoded by the EWS gene remains unknown, we investigated the putative role of EWS in RNA polymerase II (Pol II) transcription by comparing its activity with that of its structural homolog, hTAFII68. We demonstrate that a portion of EWS is able to associate with the basal transcription factor TFIID, which is composed of the TATA-binding protein (TBP) and TBP-associated factors (TAFIIs). In vitro binding studies revealed that both EWS and hTAFII68 interact with the same TFIID subunits, suggesting that the presence of EWS and that of hTAFII68 in the same TFIID complex may be mutually exclusive. Moreover, EWS is not exclusively associated with TFIID but, similarly to hTAFII68, is also associated with the Pol II complex. The subunits of Pol II that interact with EWS and hTAFII68 have been identified, confirming the association with the polymerase. In contrast to EWS, the tumorigenic EWS-FLI-1 fusion protein is not associated with either TFIID or Pol II in Ewing cell nuclear extracts. These observations suggest that EWS and EWS-FLI-1 may play different roles in Pol II transcription.
Animals↗
[Cystic polyps of the stomach: review of our case series].
The Authors report their experience with gastric polyps based upon 3,384 endoscopies performed from October 1992 to August 1995. The incidence of cystic polyps with respect to the examinations performed and to the number of gastric polyps found was 0.45% and 21.3% respectively. The cases were taken into account with respect to sex, age, number of lesions, location, size and association to Gardner's syndrome. A comparison between the observed cases and a comprehensive review of the relevant Literature was performed.
Female↗
hTAF(II)68, a novel RNA/ssDNA-binding protein with homology to the pro-oncoproteins TLS/FUS and EWS is associated with both TFIID and RNA polymerase II.
TFIID is the main sequence-specific DNA-binding component of the RNA polymerase II (Pol II) transcriptional machinery. It is a multiprotein complex composed of the TATA-binding protein (TBP) and TBP-associated factors (TAF(II)s). Here we report the cloning and characterization of a novel human TBP-associated factor, hTAF(II)68. It contains a consensus RNA-binding domain (RNP-CS) and binds not only RNA, but also single stranded (ss) DNA. hTAF(II)68 shares extensive sequence similarity with TLS/FUS and EWS, two human nuclear RNA-binding pro-oncoproteins which are products of genes commonly translocated in human sarcomas. Like hTAF(II)68, TLS/FUS is also associated with a sub-population of TFIID complexes chromatographically separable from those containing hTAF(II)68. Therefore, these RNA and/or ssDNA-binding proteins may play specific roles during transcription initiation at distinct promoters. Moreover, we demonstrate that hTAF(II)68 co-purifies also with the human RNA polymerase II and can enter the preinitiation complex together with Pol II.
Amino Acid Sequence↗
[Large cystic polyps of the stomach].
The Authors report the case of a 83 year old woman with large cystic polyps of the stomach. Gastric cystic polyps are polypoid lesions which may develop following functional disorders such as increased mucosal stimulation by gastrin, or excessive retention of gastric secretions. The incidence of these polyps is variable, depending on their being underestimated since they are not always macroscopically visible. The case here reported is very interesting not only for the number of lesions (over 50), but also for their size (5-25 mm in diameter).
Aged↗
A monoclonal inhibition enzyme immunoassay for detection of antibodies against hepatitis B core antigen: confirmation of an immunodominant epitope.
Monoclonal antibodies (mAbs) were raised against hepatitis B virus core produced by a recombinant clone of Escherichia coli (rHBc). The three mAbs recognized rHBc by Western blot, suggesting that they reacted with non-conformational epitopes. Competition experiments between mAbs and human anti-HBc sera confirmed the existence of an immunodominant HBc epitope within the viral antigen. A monoclonal competition enzyme immunoassay using an IgM mAb conjugated to biotin and streptavidin-peroxidase as the detection system yielded 99% sensitivity and 100% specificity, when compared to other commercial assays.
Animals↗
[Monolateral pseudotumor mammographic appearance of fibrous dysplasia. Report of 3 cases].
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Aged↗
[Proliferative pathology of the mammary ducts. Diagnostic value of ductogalactography and cytologic correlations].
Three hundred and thirty-six patients with nipple discharge and neither physical signs at breast examination nor pathological findings at mammography, were observed from 1984 to 1988 and studied by means of ductogalactography and cytology of discharge. Of this group, 76 patients (22.6%) underwent surgery and histology. In 65/76 cases proliferative pathologic conditions were demonstrated: 51 single/multiple papillomas and 14 carcinomas. Ductogalactography suggested proliferative pathologic conditions in 59 cases and cytology of discharge showed blood in 44 patients, papillary clusters in 23, and atypical cells in 15 (both as single occurrences and in association). In cancer patients discharge appeared to be mostly spontaneous, monoductal and blood-stained. In papillomas, induced discharge was almost as frequent as spontaneous discharge, serous discharge was almost as frequent as blood-stained discharge, and milky discharge was also present. Ductogalactography confirmed its value in the diagnosis of proliferative pathologic conditions of the mammary ducts, being especially useful to detect carcinomas without palpable tumors. Cytology of discharge had poorer diagnostic significance.
Adult↗