The family of heterochromatin protein 1 (HP1) isoforms is essential for chromatin packaging, regulation of gene expression, and repair of damaged DNA. Here we document that γ-radiation reduced the number of HP1α-positive foci, but not HP1β and HP1γ foci, located in the vicinity of the fibrillarin-positive region of the nucleolus. The additional analysis confirmed that γ-radiation has the ability to significantly decrease the level of HP1α in rDNA promoter and rDNA encoding 28S rRNA. By mass spectrometry, we showed that treatment by γ-rays enhanced the HP1β serine 88 phosphorylation (S88ph), but other analyzed modifications of HP1β, including S161ph/Y163ph, S171ph, and S174ph, were not changed in cells exposed to γ-rays or treated by the HDAC inhibitor (HDACi). Interestingly, a combination of HDACi and γ-radiation increased the level of HP1α and HP1γ. The level of HP1β remained identical before and after the HDACi/γ-rays treatment, but HDACi strengthened HP1β interaction with the KRAB-associated protein 1 (KAP1) protein. Conversely, HP1γ did not interact with KAP1, although approximately 40% of HP1γ foci co-localized with accumulated KAP1. Especially HP1γ foci at the periphery of nucleoli were mostly absent of KAP1. Together, DNA damage changed the morphology, levels, and interaction properties of HP1 isoforms. Also, γ-irradiation-induced hyperphosphorylation of the HP1β protein; thus, HP1β-S88ph could be considered as an important marker of DNA damage.

• Klíčová slova
• FLIM-FRET, HP1, epigenetics, irradiation, mass spectrometry, nucleolus, phosphorylation,
• MeSH
• buněčné jadérko metabolismus   MeSH
• chromozomální proteiny, nehistonové metabolismus   MeSH
• fosforylace MeSH
• HeLa buňky MeSH
• homolog proteinu s chromoboxem 5 MeSH
• lidé MeSH
• nádorové buňky kultivované MeSH
• optické zobrazování MeSH
• poškození DNA MeSH
• rezonanční přenos fluorescenční energie MeSH
• serin metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• CBX1 protein, human MeSH Prohlížeč
• CBX5 protein, human MeSH Prohlížeč
• chromozomální proteiny, nehistonové MeSH
• homolog proteinu s chromoboxem 5 MeSH
• serin MeSH

Mammalian heterochromatin protein 1 (HP1alpha, HP1beta, HP1gamma subtypes) and transcriptional intermediary factor TIF1beta play an important role in the regulation of chromatin structure and function. Here, we investigated the nuclear arrangement of these proteins during differentiation of embryonal carcinoma P19 cells into primitive endoderm and into the neural pathway. Additionally, the differentiation potential of trichostatin A (TSA) and 5-deoxyazacytidine (5-dAzaC) was studied. In 70% of the cells from the neural pathway and in 20% of TSA-stimulated cells, HP1alpha and HP1beta co-localized and associated with chromocentres (clusters of centromeres), which correlated with clustering of TIF1beta at these heterochromatic regions. The cell types that we studied were also characterized by a pronounced focal distribution of HP1gamma. The above-mentioned nuclear patterns of HP1 and TIF1beta proteins were completely different from the nuclear patterns observed in the remaining cell types investigated, in which HP1alpha was associated with chromocentres while HP1beta and HP1gamma were largely localized in distinct nuclear regions. Moreover, a dispersed nuclear distribution of TIF1beta was observed. Our findings showed that the nuclear arrangement of HP1 subtypes and TIF1beta is differentiation specific, and seems to be more important than changes in the levels of these proteins, which were relatively stable during all the induced differentiation processes.

• MeSH
• azacytidin analogy a deriváty   farmakologie   MeSH
• buněčná diferenciace účinky léků   fyziologie   MeSH
• buněčné jádro metabolismus   MeSH
• centromera metabolismus   MeSH
• chromozomální proteiny, nehistonové genetika   metabolismus   MeSH
• decitabin MeSH
• homolog proteinu s chromoboxem 5 MeSH
• imunohistochemie MeSH
• inhibitory enzymů farmakologie   MeSH
• inhibitory histondeacetylas MeSH
• jaderné proteiny metabolismus   MeSH
• konfokální mikroskopie MeSH
• kyseliny hydroxamové farmakologie   MeSH
• metylace DNA účinky léků   MeSH
• nádorové buněčné linie MeSH
• podjednotky proteinů genetika   metabolismus   MeSH
• rekombinantní fúzní proteiny genetika   metabolismus   MeSH
• signální transdukce účinky léků   MeSH
• transkripční faktory metabolismus   MeSH
• western blotting MeSH
• zelené fluorescenční proteiny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• azacytidin MeSH
• chromozomální proteiny, nehistonové MeSH
• decitabin MeSH
• homolog proteinu s chromoboxem 5 MeSH
• inhibitory enzymů MeSH
• inhibitory histondeacetylas MeSH
• jaderné proteiny MeSH
• kyseliny hydroxamové MeSH
• podjednotky proteinů MeSH
• rekombinantní fúzní proteiny MeSH
• transcriptional intermediary factor 1 MeSH Prohlížeč
• transkripční faktory MeSH
• trichostatin A MeSH Prohlížeč
• zelené fluorescenční proteiny MeSH