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Naum-Ongania G.,National University of La Plata | Diaz V.M.,Institute Municipal dInvestigacio Medica IMIM | Blasi F.,Istituto di Oncologia Molecolare | Rivera-Pomar R.,National University of La Plata
Transcription | Year: 2013

The HoxB cluster expression is activated by retinoic acid and transcribed in a collinear manner. The DNA-binding Pknox1-Pbx1 complex modulates Hox protein activity. Here, NT2-D1 teratocarcinoma cells -a model of Hox gene expression- were used to show that upon retinoic acid induction, Pknox1 co-localizes with polymeric nuclear actin. We have found that globular actin aggregates, polymeric actin, the elongating RNA polymerase II and THOC match euchromatic regions corresponding to nuclear speckles. Moreover, RNA polymerase II, N-WAS P, and transcription/splicing factors p54nrb and PSF were validated as Pknox1 interactors by tandem affinity purification. PSF pulled down with THOC and nuclear actin, both of which co-localize in nuclear speckles. Although latrunculin A slightly decreases the general level of HoxB gene expression, inhibition of nuclear actin polymerization by cytochalasin D blocks the expression of HoxB transcripts in a collinear manner. Thus, our results support the hypothesis that nuclear actin polymerization is involved in the activation of HoxB gene expression by means of nuclear speckles. © 2013 Landes Bioscience. Source

Morello V.,University of Turin | Cabodi S.,University of Turin | Sigismund S.,Istituto di Oncologia Molecolare | Camacho-Leal M.P.,University of Turin | And 5 more authors.
Oncogene | Year: 2011

Lung cancer is the leading cause of cancer death worldwide. The epidermal growth factor receptor (EGFR) represents the main target for non-small cell lung cancer (NSCLC) therapy, as its overexpression or constitutive activation contributes to malignancy and correlates with poor prognosis. Our previous work demonstrated that in epithelial cells Β1 integrin is required for propagating EGFR signaling from the plasma membrane to the nucleus. In this study, we silenced Β1 integrin in human NSCLC A549 cells. The Β1 integrin-silenced cells show a defective activation of the EGFR signaling cascade, leading to decreased in vitro proliferation, enhanced sensitivity to cisplatin and Gefitinib, impaired migration and invasive behavior. Inhibitory effects on tumor growth and on the EGFR pathway were also observed in in vivo experiments. Moreover, Β1 integrin silencing increases the amount of EGFR on the cell surface, suggesting that Β1 integrin is required for efficient constitutive EGFR turnover at the cell membrane. Although the rate of EGF internalization and recycling is not affected in silenced cells, EGFR signaling is recovered only by expression of the Rab-coupling protein RCP, indicating that Β1 integrin sustains the endocytic machinery required for EGFR signaling. Overall, these results show that Β1 integrin is an essential regulator of EGFR signaling and tumorigenic properties of lung cancer cells, and that its silencing might represent an adjuvant approach to anti-EGFR therapy. © 2011 Macmillan Publishers Limited All rights reserved. Source

Mironov A.A.,Istituto di Oncologia Molecolare | Beznoussenko G.V.,Istituto di Oncologia Molecolare
Methods in Enzymology | Year: 2012

In biology, light microscopy (LM) is usually used to study phenomena at a global scale and to look for unique or rare events, and it also provides an opportunity for live imaging, while the forte of electron microscopy (EM) is the high resolution. Observation of living cells under EM is still impossible. Traditionally, LM and EM observations are carried out in different populations of cells/tissues. The advent of true correlative light-electron microscopy (CLEM) has allowed high-resolution imaging by EM of the very same structure observed by LM. This chapter describes imaging with the help of CLEM. The guidelines presented herein enable researchers to analyze structure of organelles and in particular rare events captured by low-resolution imaging of a population or transient events captured by live imaging can now also be studied at high resolution by EM. © 2012 Elsevier Inc. Source

Thompson B.J.,London Research Institute | Perez F.,University Pierre and Marie Curie | Vaccari T.,Istituto di Oncologia Molecolare
EMBO Reports | Year: 2012

The ESF-EMBO meeting on Cell Polarity and Membrane Traffic took place in Poland in April 2012. It brought together scientists from two once separate fields and highlighted their emerging interdependence. The wealth of scientific insights and discoveries presented laid a path for future research. © 2012 European Molecular Biology Organization. Source

Amson R.,CNRS Laboratory of Biology and Applied Pharmacology | Pece S.,Istituto di Oncologia Molecolare | Pece S.,Catholic University of Leuven | Marine J.-C.,University of Milan | And 4 more authors.
Trends in Cell Biology | Year: 2013

Evolutionary conserved and pleiotropic, the TPT1/TCTP gene (translationally controlled tumor protein, also called HRF, fortilin), encodes a highly structured mRNA shielded by ribonucleoproteins and closely resembling viral particles. This mRNA activates, as do viruses, protein kinase R (PKR). The TPT1/TCTP protein is structurally similar to mRNA-helicases and MSS4. TPT1/TCTP has recently been identified as a prognostic factor in breast cancer and a critical regulator of the tumor suppressor p53 and of the cancer stem cell (SC) compartment. Emerging evidence indicates that TPT1/TCTP is key to phenotypic reprogramming, as shown in the process of tumor reversion and possibly in pluripotency. We provide here an overview of these diverse functions of TPT1/TCTP. © 2012 Elsevier Ltd. Source

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