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Forzati F.,University of Naples Federico II | Federico A.,University of Naples Federico II | Pallante P.,University of Naples Federico II | Colamaio M.,University of Naples Federico II | And 14 more authors.
Biology Open | Year: 2014

We have recently generated knockout mice for the Cbx7 gene, coding for a polycomb group protein that is downregulated in human malignant neoplasias. These mice develop liver and lung adenomas and carcinomas, which confirms a tumour suppressor role for CBX7. The CBX7 ability to downregulate CCNE1 expression likely accounts for the phenotype of the Cbx7-null mice. Unexpectedly, Cbx7-knockout mice had a higher fat tissue mass than wild-type, suggesting a role of CBX7 in adipogenesis. Consistently, we demonstrate that Cbx7-null mouse embryonic fibroblasts go towards adipocyte differentiation more efficiently than their wild-type counterparts, and this effect is Cbx7 dose-dependent. Similar results were obtained when Cbx7-null embryonic stem cells were induced to differentiate into adipocytes. Conversely, mouse embryonic fibroblasts and human adipose-derived stem cells overexpressing CBX7 show an opposite behaviour. These findings support a negative role of CBX7 in the control of adipocyte cell growth and differentiation. © 2014. Published by The Company of Biologists Ltd. Source


Rinaldo C.,Laboratorio Of Oncogenesi Molecolare | Moncada A.,Laboratorio Of Oncogenesi Molecolare | Gradi A.,Laboratorio Of Oncogenesi Molecolare | Ciuffini L.,Laboratorio Of Oncogenesi Molecolare | And 13 more authors.
Molecular Cell | Year: 2012

Failure in cytokinesis, the final step in cell division, by generating tetra- and polyploidization promotes chromosomal instability, a hallmark of cancer. Here we show that HIPK2, a kinase involved in cell fate decisions in development and response to stress, controls cytokinesis and prevents tetraploidization through its effects on histone H2B. HIPK2 binds and phosphorylates histone H2B at S14 (H2B-S14 P), and the two proteins colocalize at the midbody. HIPK2 depletion by targeted gene disruption or RNA interference results in loss of H2B-S14 P at the midbody, prevention of cell cleavage, and tetra- and polyploidization. In HIPK2 null cells, restoration of wild-type HIPK2 activity or expression of a phosphomimetic H2B-S14D derivative abolishes cytokinesis defects and rescues cell proliferation, showing that H2B-S14 P is required for a faithful cytokinesis. Overall, our data uncover mechanisms of a critical HIPK2 function in cytokinesis and in the prevention of tetraploidization. © 2012 Elsevier Inc. Source


De Santis M.,University of Rome La Sapienza | Rinaldi F.,University of Rome La Sapienza | Falcone E.,Laboratorio Of Oncogenesi Molecolare | Lucidi S.,University of Rome La Sapienza | And 3 more authors.
Bioinformatics | Year: 2014

Motivation: The identification of cell cycle-regulated genes through the cyclicity of messenger RNAs in genome-wide studies is a difficult task due to the presence of internal and external noise in microarray data. Moreover, the analysis is also complicated by the loss of synchrony occurring in cell cycle experiments, which often results in additional background noise. Results: To overcome these problems, here we propose the LEON (LEarning and OptimizatioN) algorithm, able to characterize the 'cyclicity degree' of a gene expression time profile using a two-step cascade procedure. The first step identifies a potentially cyclic behavior by means of a Support Vector Machine trained with a reliable set of positive and negative examples. The second step selects those genes having peak timing consistency along two cell cycles by means of a non-linear optimization technique using radial basis functions. To prove the effectiveness of our combined approach, we use recently published human fibroblasts cell cycle data and, performing in vivo experiments, we demonstrate that our computational strategy is able not only to confirm well-known cell cycle-regulated genes, but also to predict not yet identified ones. © 2013 The Author. Source


Pierantoni G.M.,National Research Council Italy | Esposito F.,National Research Council Italy | Tornincasa M.,National Research Council Italy | Rinaldo C.,Laboratorio Of Oncogenesi Molecolare | And 3 more authors.
Journal of Biological Chemistry | Year: 2011

HIPK2 is a serine/threonine kinase that acts as a coregulator of an increasing number of factors involved in cell survival and proliferation during development and in response to different types of stress. Here we report on a novel target of HIPK2, the cyclin-dependent kinase inhibitor p27kip1. HIPK2 phosphorylates p27kip1 in vitro and in vivo at serine 10, an event that accounts for 80% of the total p27kip1 phosphorylation and plays a crucial role in the stability of the protein. Indeed, HIPK2 depletion by transient or stable RNA interference in tumor cells of different origin was consistently associated with strong reduction of p27kip1 phosphorylation at serine 10 and of p27kip1 stability. An initial evaluation of the functional relevance of this HIPK2-mediated regulation of p27kip1 revealed a contribution to cell motility, rather than to cell proliferation, but only in cells that do not express wild-type p53. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc. Source

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