Control of DNA replication by NCOA4 protein in HeLa cells

Provitera, Livia Control of DNA replication by NCOA4 protein in HeLa cells. [Tesi di dottorato] (Inedito)

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This dissertation is focused on the functional characterization of NCOA4 protein, and in particular on its role in controlling DNA replication in HeLa cells. In human papillary thyroid carcinoma the rearrangement of RET protooncogene, in particular of its tyrosine kinase domain, with the 5’ portion of a number of heterologous genes, generates the RET/papillary thyroid carcinoma (PTC) oncogenes. One of the most frequent and aggressive variants of these recombination events is the fusion of the intracellular kinase-encoding domain of RET to the first 238 amino acids of a gene named NCOA4 (ELE1/ARA70/RFG), generating the RET/PTC3 oncogene. We previously isolated the Mini-Chromosome Maintenance 7 (MCM7) protein as an interactor of NCOA4. MCM7 is a component of an heteroexameric complex named MCM2-7, considered a master regulator of DNA replication, acting both during DNA replication origins licensing, as part of the Pre-Replication Complex (Pre-RC), and during nascent strand elongation, as the major helicase of the fork. In Xenopus laevis egg extracts NCOA4 blocks DNA replication. Hindrance of DNA replication is mediated by block of MCM2-7 helicase function, leaving untouched origin licensing and activation. Here we show that NCOA4 and MCM7 proteins interact at the endogenous level in HeLa cells and this interaction is confined in the nucleus and takes place preferentially on chromatin. Moreover, in HeLa cells, NCOA4 binds canonical DNA replication origins, such as those prospicient to the c-Myc or to the Lamin B2 gene. RNAi-mediated depletion of NCOA4 accelerates the onset of DNA replication, whereas adoptive NCOA4 overexpression decreases cell growth and DNA synthesis. Our results suggest that NCOA4/RET rearrangement might represent a novel paradigm of a cancer-associated chromosome rearrangement that directly targets a gene that controls cell proliferation.

Tipologia di documento:Tesi di dottorato
Parole chiave:DNA replication
Settori scientifico-disciplinari MIUR:Area 06 Scienze mediche > MED/04 PATOLOGIA GENERALE
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Stato del full text:Accessibile
Istituzione:Università degli studi di Napoli "Federico II"
Dipartimento o Struttura:Biologia e Patologia Cellulare e Molecolare "L.Califano"
Tipo di tesi:Dottorato
Stato dell'Eprint:Inedito
Scuola di dottorato:Medicina Molecolare
Denominazione del dottorato:Oncologia ed Endocrinologia Molecolare
Ciclo di dottorato:XXI
Numero di sistema:3134
Depositato il:09 Novembre 2009 11:15
Ultima modifica:09 Settembre 2010 12:43

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