Although actin monomers polymerize into filaments in the cytoplasm, the form of actin in the nucleus remains elusive. We searched for the form and function of β-actin fused to nuclear localization signal and to enhanced yellow fluorescent protein (EN-actin). Our results reveal that EN-actin is either dispersed in the nucleoplasm (homogenous EN-actin) or forms bundled filaments in the nucleus (EN-actin filaments). Formation of such filaments was not connected with increased EN-actin levels. Among numerous actin-binding proteins tested, only cofilin is recruited to the EN-actin filaments. Overexpression of EN-actin causes increase in the nuclear levels of actin-related protein 3 (Arp3). Although Arp3, a member of actin nucleation complex Arp2/3, is responsible for EN-actin filament nucleation and bundling, the way cofilin affects nuclear EN-actin filaments dynamics is not clear. While cells with homogenous EN-actin maintained unaffected mitosis during which EN-actin re-localizes to the plasma membrane, generation of nuclear EN-actin filaments severely decreases cell proliferation and interferes with mitotic progress. The introduction of EN-actin manifests in two mitotic-inborn defects-formation of binucleic cells and generation of micronuclei-suggesting that cells suffer aberrant cytokinesis and/or impaired chromosomal segregation. In interphase, nuclear EN-actin filaments passed through chromatin region, but do not co-localize with either chromatin remodeling complexes or RNA polymerases I and II. Surprisingly presence of EN-actin filaments was connected with increase in the overall transcription levels in the S-phase by yet unknown mechanism. Taken together, EN-actin can form filaments in the nucleus which affect important cellular processes such as transcription and mitosis.

• MeSH
• aktiny metabolismus   MeSH
• bakteriální proteiny metabolismus   MeSH
• buněčné jádro metabolismus   MeSH
• faktory depolymerizující aktin MeSH
• genetická transkripce MeSH
• HEK293 buňky MeSH
• lidé MeSH
• luminescentní proteiny metabolismus   MeSH
• mikrofilamenta metabolismus   MeSH
• mitóza genetika   MeSH
• nádorové buněčné linie MeSH
• protein 3 související s aktinem biosyntéza   metabolismus   MeSH
• restrukturace chromatinu MeSH
• RNA-polymerasa I genetika   MeSH
• RNA-polymerasa II genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aktiny MeSH
• bakteriální proteiny MeSH
• faktory depolymerizující aktin MeSH
• luminescentní proteiny MeSH
• protein 3 související s aktinem MeSH
• RNA-polymerasa I MeSH
• RNA-polymerasa II MeSH
• yellow fluorescent protein, Bacteria MeSH Prohlížeč

Simultaneous detection of biological molecules by means of indirect immunolabeling provides valuable information about their localization in cellular compartments and their possible interactions in macromolecular complexes. While fluorescent microscopy allows for simultaneous detection of multiple antigens, the sensitive electron microscopy immunodetection is limited to only two antigens. In order to overcome this limitation, we prepared a set of novel, shape-coded metal nanoparticles readily discernible in transmission electron microscopy which can be conjugated to antibodies or other bioreactive molecules. With the use of novel nanoparticles, various combinations with commercial gold nanoparticles can be made to obtain a set for simultaneous labeling. For the first time in ultrastructural histochemistry, up to five molecular targets can be identified simultaneously. We demonstrate the usefulness of the method by mapping of the localization of nuclear lipid phosphatidylinositol-4,5-bisphosphate together with four other molecules crucial for genome function, which proves its suitability for a wide range of biomedical applications.

• MeSH
• aktiny metabolismus   MeSH
• barvení a značení metody   MeSH
• buněčné jádro MeSH
• elektronová mikroskopie MeSH
• fosfatidylinositol-4,5-difosfát metabolismus   MeSH
• HeLa buňky MeSH
• imunohistochemie metody   MeSH
• jaderné proteiny metabolismus   MeSH
• kovové nanočástice chemie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nukleofosmin MeSH
• proteiny buněčného cyklu MeSH
• protilátky imunologie   MeSH
• ribonukleoproteiny malé jaderné metabolismus   MeSH
• transportní proteiny metabolismus   MeSH
• zlato chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aktiny MeSH
• fosfatidylinositol-4,5-difosfát MeSH
• jaderné proteiny MeSH
• nukleofosmin MeSH
• proteiny buněčného cyklu MeSH
• protilátky MeSH
• ribonukleoproteiny malé jaderné MeSH
• SMC2 protein, human MeSH Prohlížeč
• transportní proteiny MeSH
• zlato MeSH

Actin is a well-known protein that has shown a myriad of activities in the cytoplasm. However, recent findings of actin involvement in nuclear processes are overwhelming. Actin complexes in the nucleus range from very dynamic chromatin-remodeling complexes to structural elements of the matrix with single partners known as actin-binding proteins (ABPs). This review summarizes the recent findings of actin-containing complexes in the nucleus. Particular attention is given to key processes like chromatin remodeling, transcription, DNA replication, nucleocytoplasmic transport and to actin roles in nuclear architecture. Understanding the mechanisms involving ABPs will definitely lead us to the principles of the regulation of gene expression performed via concerting nuclear and cytoplasmic processes.

• MeSH
• aktiny chemie   metabolismus   MeSH
• biologické modely MeSH
• buněčné jádro chemie   metabolismus   MeSH
• lidé MeSH
• mikrofilamentové proteiny chemie   metabolismus   MeSH
• oprava DNA MeSH
• replikace DNA MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• aktiny MeSH
• mikrofilamentové proteiny MeSH