Epigenetic up-regulation of ribosome biogenesis and more aggressive phenotype triggered by the lack of the histone demethylase JHDM1B in mammary epithelial cells
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Alice Galbiati1, Marianna Penzo1, Maria Giulia Bacalini1, Carmine Onofrillo1, Ania Naila Guerrieri1, Paolo Garagnani1, Claudio Franceschi1, Davide Treré1, Lorenzo Montanaro1
1Department of Experimental, Diagnostic, and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
Lorenzo Montanaro, email: [email protected]
Keywords: histone modification, JHDM1B, rDNA, ribosome biogenesis, cancer cells
Received: April 28, 2016 Accepted: March 03, 2017 Published: March 14, 2017
The alterations of ribosome biogenesis and protein synthesis play a direct role in the development of tumors. The accessibility and transcription of ribosomal genes is controlled at several levels, with their epigenetic regulation being one of the most important. Here we explored the JmjC domain-containing histone demethylase 1B (JHDM1B) function in the epigenetic control of rDNA transcription. Since JHDM1B is a negative regulator of gene transcription, we focused on the effects induced by JHDM1B knock-down (KD). We studied the consequences of stable inducible JHDM1B silencing in cell lines derived from transformed and untransformed mammary epithelial cells. In these cellular models, prolonged JHDM1B downregulation triggered a surge of 45S pre-rRNA transcription and processing, associated with a re-modulation of the H3K36me2 levels at rDNA loci and with changes in DNA methylation of specific CpG sites in rDNA genes. We also found that after JHDM1B KD, cells showed a higher ribosome content: which were engaged in mRNA translation. JHDM1B KD and the consequent stimulation of ribosomes biogenesis conferred more aggressive features to the tested cellular models, which acquired a greater clonogenic, staminal and invasive potential. Taken together, these data indicate that the reduction of JHDM1B leads to a more aggressive cellular phenotype in mammary gland cells, by virtue of its negative regulatory activity on ribosome biogenesis.
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