Tumor suppressor p53 is a key player in the cell response to DNA damage that suffers by frequent inactivating aberrations. Some of them disturb p53 oligomerization and influence cell decision between proliferation, growth arrest and apoptosis. Active p53 resides mostly in the nucleus, degradation occurs in the cytoplasm. Acute myeloid leukemia (AML)-related mutation of NPM (NPMmut) induces massive mislocalization of p53 to the cytoplasm, which might be related to leukemia initiation. Since both proteins interact and execute their function as oligomers, we investigated the role of perturbed p53 oligomerization in the p53 mislocalization process in live cells by FLIM (fluorescence lifetime imaging microscopy), fluorescence anisotropy imaging (FAIM), fluorescence cross-correlation spectroscopy (FCCS) and immunochemical methods. On a set of fluorescently labeled p53 variants, monomeric R337G and L344P, dimeric L344A, and multimeric D352G and A353S, we correlated their cellular localization, oligomerization and interaction with NPMmut. Interplay between nuclear export signal (NES) and nuclear localization signal (NLS) of p53 was investigated as well. While NLS was found critical for the nuclear p53 localization, NES plays less significant role. We observed cytoplasmic translocation only for multimeric A353S variant with sufficient stability and strong interaction with NPMmut. Less stable multimer D352G and L344A dimer were not translocated, monomeric p53 variants always resided in the nucleus independently of the presence of NPMmut and NES intactness. Oligomeric state of NPMmut is not required for p53 translocation, which happens also in the presence of the nonoligomerizing NPMmut variant. The prominent structural and functional role of the R337 residue is shown.

• MeSH
• akutní myeloidní leukemie * genetika   metabolismus   MeSH
• buněčné jádro metabolismus   MeSH
• cytoplazma metabolismus   MeSH
• jaderné lokalizační signály metabolismus   MeSH
• jaderné proteiny * genetika   metabolismus   MeSH
• lidé MeSH
• multimerizace proteinu MeSH
• mutace * MeSH
• nádorové buněčné linie MeSH
• nádorový supresorový protein p53 * metabolismus   genetika   chemie   MeSH
• nukleofosmin MeSH
• signály pro jaderný export MeSH
• transport proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• jaderné lokalizační signály MeSH
• jaderné proteiny * MeSH
• nádorový supresorový protein p53 * MeSH
• NPM1 protein, human MeSH Prohlížeč
• nukleofosmin MeSH
• signály pro jaderný export MeSH
• TP53 protein, human MeSH Prohlížeč

Nucleophosmin (NPM) interaction with tumor suppressor p53 is a part of a complex interaction network and considerably affects cellular stress response. The impact of NPM1 mutations on its interaction with p53 has not been investigated yet, although consequences of NPMmut-induced p53 export to the cytoplasm are important for understanding the oncogenic potential of these mutations. We investigated p53-NPM interaction in live HEK-293T cells by FLIM-FRET and in cell lysates by immunoprecipitation. eGFP lifetime-photoconversion was used to follow redistribution dynamics of NPMmut and p53 in Selinexor-treated cells. We confirmed the p53-NPMwt interaction in intact cells and newly documented that this interaction is not compromised by the NPM mutation causing displacement of p53 to the cytoplasm. Moreover, the interaction was not abolished for non-oligomerizing NPM variants with truncated oligomerization domain, suggesting that oligomerization is not essential for interaction of NPM forms with p53. Inhibition of the nuclear exporter XPO1 by Selinexor caused expected nuclear relocalization of both NPMmut and p53. However, significantly different return rates of these proteins indicate nontrivial mechanism of p53 and NPMmut cellular trafficking. The altered p53 regulation in cells expressing NPMmut offers improved understanding to help investigational strategies targeting these mutations.

• Klíčová slova
• FLIM-FRET, Selinexor, acute myeloid leukemia, mutation, nucleophosmin, p53, photoconversion,
• Publikační typ
• časopisecké články MeSH

Nucleophosmin (NPM) mutations causing its export from the nucleoli to the cytoplasm are frequent in acute myeloid leukemia (AML). Due to heterooligomerization of wild type NPM with the AML-related mutant, the wild-type becomes misplaced from the nucleoli and its functions are significantly altered. Dissociation of NPM heterooligomers may thus restore the proper localization and function of wild-type NPM. NSC348884 is supposed to act as a potent inhibitor of NPM oligomerization. The effect of NSC348884 on the NPM oligomerization was thoroughly examined by fluorescence lifetime imaging with utilization of FRET and by a set of immunoprecipitation and electrophoretic methods. Leukemia-derived cell lines and primary AML cells as well as cells transfected with fluorescently labeled NPM forms were investigated. Our results clearly demonstrate that NSC348884 does not inhibit formation of NPM oligomers neither in vivo nor in vitro. Instead, we document that NSC348884 cytotoxicity is rather associated with modified cell adhesion signaling. The cytotoxic mechanism of NSC348884 has therefore to be reconsidered.

• MeSH
• apoptóza účinky léků   MeSH
• HEK293 buňky MeSH
• indoly farmakologie   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• leukemie farmakoterapie   genetika   metabolismus   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nukleofosmin MeSH
• protinádorové látky farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• indoly MeSH
• jaderné proteiny MeSH
• NPM1 protein, human MeSH Prohlížeč
• NSC 348884 MeSH Prohlížeč
• nukleofosmin MeSH
• protinádorové látky MeSH

P21-activated kinases (PAK) are key effectors of the small GTPases Rac1 and Cdc42, as well as of Src family kinases. In particular, PAK1 has several well-documented roles, both kinase-dependent and kinase-independent, in cancer-related processes, such as cell proliferation, adhesion, and migration. However, PAK1 properties and functions have not been attributed to individual PAK1 isoforms: besides the full-length kinase (PAK1-full), a splicing variant lacking the exon 15 (PAK1Δ15) is annotated in protein databases. In addition, it is not clear if PAK1 and PAK2 are functionally overlapping. Using fluorescently tagged forms of human PAK1-full, PAK1Δ15, and PAK2, we analyzed their intracellular localization and mutual interactions. Effects of PAK inhibition (IPA-3, FRAX597) or depletion (siRNA) on cell-surface adhesion were monitored by real-time microimpedance measurement. Both PAK1Δ15 and PAK2, but not PAK1-full, were enriched in focal adhesions, indicating that the C-terminus might be important for PAK intracellular localization. Using coimmunoprecipitation, we documented direct interactions among the studied PAK group I members: PAK1 and PAK2 form homodimers, but all possible heterocomplexes were also detected. Interaction of PAK1Δ15 or PAK2 with PAK1-full was associated with extensive PAK1Δ15/PAK2 cleavage. The impedance measurements indicate, that PAK2 depletion slows down cell attachment to a surface, and that PAK1-full is involved in cell spreading. Altogether, our data suggest a complex interplay among different PAK group I members, which have non-redundant functions.

• MeSH
• buněčná adheze genetika   fyziologie   MeSH
• buněčné linie MeSH
• exony genetika   MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• p21 aktivované kinasy genetika   metabolismus   MeSH
• pohyb buněk genetika   fyziologie   MeSH
• proliferace buněk genetika   fyziologie   MeSH
• signální transdukce genetika   fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• p21 aktivované kinasy MeSH
• PAK1 protein, human MeSH Prohlížeč
• PAK2 protein, human MeSH Prohlížeč

Acute myeloid leukemia with mutated nucleophosmin (NPMc+ AML) forms a distinct AML subgroup with better prognosis which can potentially be associated with immune response against the mutated nucleophosmin (NPM). As the T-cell-mediated immunity involves antigen presentation on HLA class I molecules, we hypothesized that individuals with suitable HLA type could be less prone to develop NPMc+ AML. We compared HLA class I distribution in NPMc+ AML patient cohort (398 patients from 5 centers) with the HLA allele frequencies of the healthy population and found HLA-A*02, B*07, B*40 and C*07 underrepresented in the NPMc+ AML group. Presence of B*07 or C*07:01 antigen was associated with better survival in patients without concomitant FLT3 internal tandem duplication. Candidate NPM-derived immunopeptides were found for B*40 and B*07 using prediction software tools. Our findings suggest that a T-cell-mediated immune response could actually explain better prognosis of NPMc+ patients and provide a rationale for attempts to explore the importance of immunosuppressive mechanisms in this AML subgroup.

• MeSH
• akutní myeloidní leukemie * genetika   imunologie   mortalita   MeSH
• buněčná imunita * MeSH
• dospělí MeSH
• jaderné proteiny * genetika   imunologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• MHC antigeny I. třídy * genetika   imunologie   MeSH
• míra přežití MeSH
• nádorové proteiny * genetika   imunologie   MeSH
• nukleofosmin MeSH
• prevalence MeSH
• přežití bez známek nemoci MeSH
• senioři MeSH
• T-lymfocyty imunologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• jaderné proteiny * MeSH
• MHC antigeny I. třídy * MeSH
• nádorové proteiny * MeSH
• NPM1 protein, human MeSH Prohlížeč
• nukleofosmin MeSH