Chromatin remodeling, chromosome abnormalities and cell death under histone deacetylase inhibition in HeLa and 3T3 cells

Author(s)

Marina Barreto Felisbino

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2012-02-24

Examining board members

Maria Luiza Silveira Mello; Luciana Bolsoni Lourenço; Maurício Machaim Franco

• Advisor: Maria Luiza Silveira Mello

Abstract

Valproic acid (VPA) is a potent anticonvulsant that inhibits class I histone deacetylases (HDACi) in several cell types. Seeking to know whether the chromatin structure would change when the action of HDACi, we investigated whether VPA would affect chromatin supraorganization of tumoral HeLa cells and NIH 3T3 cells, this latter characterized by presenting areas of conspicuos heterochromatin. This information was associated with enzymatic activity of HDACs as well as the level of H3 histone acetylation in these cell models treated with VPA. The frequency of chromosome abnormalities and cell death and mitotic indices were also investigated. VPA-treated cells at concentration 0.05, 0.5 and 1.0 mM for 1-24 h were subjected to the Feulgen reaction and analysed by automatic scanning microspectrophotometry and optical microscopy. Western blots, enzymatic analysis and TUNEL assay were also performed in this study. Trichostatin A (TSA)-treated cells, an HDACi whose activity is broader than VPA, were used as positive control. Chromatin decondensation was demonstrated under all TSA and VPA treatments and was associated with decrease in HDAC activity and with increase in the level of H3 histone acetylation. This chromatin textural change also affected heterochromatic areas of NIH 3T3 cells. No changes in chromosome abnormalities, mitotic indices or morphologically identified cell death were found in both cellular models with the VPA treatment conditions mentioned above, although there was an increase of DNA fragmentation after a 24 h-VPA treatment and a 4 h-TSA treatment in HeLa cells. Decrease in cell proliferation in HeLa cells ocurred only under a 5.0 mM 48 h-VPA treatment. The results indicate that VPA and TSA promote chromatin remodeling in tumoral HeLa cells and fibroblastic NIH 3T3 cells, which may be attrituted to their HDACi action. It may not be discarded, however, that VPA acts on other nuclear proteins whose expression could be reducted under its action (AU)

• FAPESP's process: 09/11763-0 - Chromatin supraorganization, chromosome anomalies and cell death under conditions of histone deacetylase inhibition in HeLa and 3T3 cells
• Grantee: Marina Barreto Felisbino
• Support Opportunities: Scholarships in Brazil - Master