Research - Institute of Genetics - Developmental Genetics Unit - Laboratory of Drosophila Nuclear Actin Research

Péter VILMOS
senior research associate

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Ildikó KRISTÓ research associate
Csaba BAJUSZ Ph.D. student
Péter BORKÚTI Ph.D. student
Csilla ABONYI laboratory assistant

LABORATORY OF DROSOPHILA NUCLEAR ACTIN RESEARCH

The most dynamic component of the cytoskeleton in every eukaryotic cell is the microfilament network of linear polymers of actin subunits. Extensive research in the past decade has significantly broadened our view about the role actin plays in the life of the cell and added novel aspects to actin research. One of these new aspects is the discovery of the existence of nuclear actin which became evident only recently. In the nucleus, actin has been linked to a variety of processes including transcription and transcription regulation, RNA processing and export, chromatin organization and remodeling, DNA repair, or even nuclear envelope assembly.

One of our main research projects focuses on the biological significance of nuclear actin. We use the excellent model system, Drosophila melanogaster, and combine genetic and cell biological methods to directly test the importance of actin in the nucleus.

The numerous and important functions of the actin cytoskeleton are all enabled and carried out by at least 80 distinct actin-binding proteins in the cytoplasm. Members of the actin-binding Ezrin-Radixin-Moesin (ERM) protein family of vertebrates are major regulators of actin dynamics in the cell by crosslinking membrane proteins to the cortical actin network. The three paralogs are present in vertebrates, whereas other species, (e.g., Drosophila) have only one ERM gene. ERMs have pivotal role in cell adhesion, cell movement, and intracellular membrane trafficking processes; therefore, they are key players in cell polarity, morphogenesis, and tumor metastasis, which features have attracted outstanding interest to this protein family in the past couple of years.

We are also interested in the nuclear functions of actin-binding ERM proteins. To study the role ERMs play in the nucleus, we use advanced light microscopy and molecular biological methods, and we developed a genetic interaction screen to find nuclear interacting partners of ERMs. As model systems, we use the fruit-fly and cultured Drosophila cells.

We have demonstrated first in cultured S2 cells then in Drosophila embryos that Moe can be detected in a small amount in the interphase nucleus; its level rapidly increases during prophase, and it co-localizes with the actin network surrounding the mitotic spindle throughout mitosis. We have shown that the predicted single NLS is not necessary for the nuclear accumulation of the protein in prophase. Immuno-histochemical staining of endogenous Moe confirmed the existence of spindle association in wild-type embryos. We also found that Moe dsRNA-treated cells showed abnormal spindle morphology, which reflected a delay in mitotic progression.




Fig 1: Nuclear localization of Drosophila Moesin. A) The distribution pattern of Moesin in a polytenic, interphase nucleus. B) The accumulation of the Moesin protein (red) in the nucleus (blue - DAPI).

Selected publications

Kristó I, Bajusz C, Borsos BN, Pankotai T, Dopie J, Jankovics F, Vartiainen MK, Erdélyi M, Vilmos P. (2017) The actin binding cytoskeletal protein Moesin is involved in nuclear mRNA export. BIOCHIM BIOPHYS ACTA. 2017 Oct;1864(10):1589-1604. doi: 10.1016/j.bbamcr.2017.05.020.

Takács Zs, Jankovics F, Vilmos P, Lénárt P, Röper K, Erdélyi M. (2017) The spectraplakin short stop is an essential microtubule regulator involved in epithelial closure in Drosophila. J CELL SCI. 130(4):712-724. doi: 10.1242/jcs.193003.

Vilmos P, Kristó I, Szikora Sz, Jankovics F, Lukácsovich T, Kari B, Erdélyi M. (2016) The actin-binding ERM protein Moesin directly regulates spindle assembly and function during mitosis. CELL BIOL INT. 2016 doi: 10.1002/cbin.10607

Kristó I, Bajusz I, Bajusz Cs, Borkúti P, Vilmos P. Actin, actin-binding proteins, and actin-related proteins in the nucleus. (2016) HISTOCHEM CELL BIOL. 145(4):373-88. doi: 10.1007/s00418-015-1400-9.

Jankovics F., Henn L., Vilmos P. Intracellular skeletal structures in eukaryotes. (2015) SELECTED TOPICS FROM CONTEMPORARY EXPERIMENTAL BIOLOGY 2:155-170.

Jankovics F, Henn L, Bujna Á, Vilmos P, Spirohn K, Boutros M, Erdélyi M. (2014) Functional analysis of the Drosophila embryonic germ cell transcriptome by RNA interference. PLoS ONE 9(6):e98579. doi: 10.1371/journal.pone.0098579.

Vilmos P, Bujna A, Szuperák M, Havelda Z, Várallyay É, Szabad J, Kucerova L, Somogyi K, Kristó I, Lukácsovich T, Jankovics F, Henn L, Erdélyi M. (2013) Viability, longevity, and egg production of Drosophila melanogaster are regulated by the miR-282 microRNA. GENETICS 195(2):469-80. doi: 10.1534/genetics.113.153585.

Jankovics F, Henn L, Bujna Á, Vilmos P, Kiss N, Erdélyi M. (2011) A Functional Genomic Screen Combined with Time-Lapse Microscopy Uncovers a Novel Set of Genes Involved in Dorsal Closure of Drosophila Embryos. PLOS ONE 6:(7) p. 10.1371/journal.pone.0022229.

Vilmos P, Jankovics F, Szathmári M, Lukácsovich F, Henn L, Erdélyi M. (2009) Live imaging reveals that the Drosophila actin-binding ERM protein, moesin, co-localizes with the mitotic spindle. EUR. J. CELL BIOL 88:(10) 609-619.