Research topics
In diploid mammalian cells, some 6x109 base pairs of DNA fold as a nucleo-protein complex (i.e. chromatin) into higher-order arrays so as to fit in a nucleus measuring only 10 µm. The nucleus also contains machineries for transcription of genes and processing of RNA products, and for precise DNA replication, repair and recombination. Nuclear interior is therefore functionally highly compartmentalized, and the recent evidence points strongly to structure-related regulation of nuclear functions - however, the mechanisms forming the 3D-structure of the nucleus are still mostly obscure. We therefore employ a multi-disciplinary approach in order to study nuclear functions in relation to the higher-order nuclear structures, e.g. nuclear bodies, the nucleolus, and the nucleoskeleton. Our research concentrates on:
The relationship between nuclear compartmentalization and regulation of gene expression.
Structure, dynamics, and function of the nucleoskeleton, which might direct nuclear compartmentalization.
Functions of nuclear myosin I, actin and actin-binding proteins in transcription and gene expression.
Development of new microscopy methods for ultrastructural studies.
Current grant support
Grant Agency of the Academy of Sciences of the Czech Republic (grant: The role of PML in cellular senescence, No. IAA500390501)
Academy of Sciences of the Czech Republic (grant: New nanoparticles for ultrastructural diagnostics, No. KAN200520704)
Grant Agency of the Czech Republic (grant: Function of nuclear myosin in gene expression, No. GA204/07/1592, and grant: Molecular biology of differentiating cell, No. (204/09/H084)
Ministry of Education, Youth and Sports of the Czech Republic (grant: Center of Functional Organization of the Cell, No.: LC 545; grant: Flurescence Microscopy in Biological and Medical Research, No. LC06063; grant: Structure and irregularities of the nucleoskeleton: identification and diagnostic, No.: 2B06063); grant: Cooperative contribution of actin-and myosin-families to the chromatin dynamics and transcription in the cell nucleus, No.: ME 09101
Most important recent papers
(2002-present; names of the lab members underlined)Iben, S., Tschochner, H., Bier, M., Hozak, P., Egly, J.-M., Grummt, I.: TFIIH plays a role in RNA polymerase I transcription. Cell 109: 297-306, 2002. (PubMed)
Fuchsova, B., Novak, P., Kafkova, J., Hozak, P.: Nuclear DNA helicase II is recruited to IFN-alpha activated transcription sites at PML nuclear bodies. J. Cell Biol. 158: 463-473, 2002. (PubMed)
Fuchsová, B., Hozák, P.: The localization of nuclear DNA helicase II in diferent nuclear compartment is linked to transcription. Exp. Cell Res. 279: 260-70, 2002. (PubMed)
Philimonenko, A.A., Jackson, D.A., Hodný, Z., Janáček, J., Cook, P.R., Hozák, P.: Dynamics of DNA replication: an ultrastructural study. J. Struct. Biol. 148: 279-289, 2004. (PubMed)
Hofmann, W.A., Stojiljkovic, L., Fuchsová, B., Vargas, G.M., Mavrommatis, E., Philimonenko, V., Kysela, K., Goodrich, J.A., Lessard, J.L., Hope, T.J., Hozak, P., de Lanerolle, P.: Actin is part of pre-initiation complexes and is necessary for transcription by RNA polymerase II. Nat. Cell Biol. 6: 1094-1101, 2004. (PubMed)
Kysela, K., Philimonenko, A.A., Philimonenko, V.V., Janacek, J., Kahle, M., Hozak, P.: Nuclear distribution of actin and myosin I depends on transcriptional activity of the cell. Histochem. Cell Biol. 124: 347-58, 2005. (PubMed)
Philimonenko,
A.A., Hodny, Z., Jackson, D.A., Hozak, P.: The
microarchitecture of DNA replication domains. Histochem. Cell Biol.
125: 103-117, 2006. (PubMed)
Kahle M, Pridalova J, Spacek M, Dzijak R, Hozak P. Nuclear myosin is ubiquitously expressed and evolutionary conserved invertebrates. Histochem Cell Biol. 127: 139-148, 2006. (PubMed)
Novakova Z, Man P, Novak P, Hozak P, Hodny Z. Separation of nuclear protein complexes by blue native polyacrylamide gel electrophoresis. Electrophoresis 27:1277-1287. (PubMed)
Vlasakova J, Novakova Z, Rossmeislova L, Kahle M, Hozak P, Hodny Z. Histone deacetylase inhibitors suppress IFNalpha-induced up-regulation of promyelocytic leukemia protein. Blood 109:1373-1380, 2006. (PubMed)
Janderova-Rossmeislova L, Novakova Z, Vlasakova J, Philimonenko V, Hozak P, Hodny Z.: PML protein association with specific nucleolar structures differs in normal, tumor and senescent human cells. J Struct Biol. 159: 56-70, 2007. (PubMed)
Fulka H, St John JC, Fulka J, Hozak P. Chromatin in early mammalian embryos: achieving the pluripotent state. Differentiation 76, 3-14, 2008 (PubMed)
Stradalova V, Gaplovska-Kysela K, Hozak P. Ultrastructural and nuclear antigen preservation after high-pressure freezing/freeze-substitution and low-temperature LR White embedding of Hela cells. Histochem Cell Biol 130, 1047-52, 2008 (PubMed)
Ogushi S, Palmieri CH, Fulka H, Saitou M, Myiano T, Fulka J Jr. The maternal nucleolus is essential for early embryonic development in mammals. Science, 319, 613-16, 2008. (H. Fulka - past PhD student in the lab) (PubMed)
Dingova H, Fukalova J, Maninova M, Philimonenko VV, Hozak P. Ultrastructural localization of actin and actin-binding proteins in the nucleus. Histochem Cell Biol., in press, 2008 (PubMed)
Reviews
Hozak, P., Fakan, S.: Functional structure of the cell nucleus. Histochem. Cell Biol. 125: 1-2, 2006. (PubMed)
Teaching, lectures, public presentations
Acquisition and Processing of the Image in Microscopy - (link)
Selective course at the Faculty of Science, Charles University: Cell Nucleus and Gene Expression
syllabus (in Czech)
PhD Educative project GA ČR "Molecular biology of a differentiating cell - (link)
Microscopy immunodetection in biomedicine - (link)