DNA double-strand breaks (DSBs) represent a lethal form of DNA damage that can trigger cell death or initiate oncogenesis. The activity of RNA polymerase II (RNAPII) at the break site is required for efficient DSB repair. However, the regulatory mechanisms governing the transcription cycle at DSBs are not well understood. Here, we show that Integrator complex subunit 6 (INTS6) associates with the heterotrimeric sensor of ssDNA (SOSS1) complex (comprising INTS3, INIP and hSSB1) to form the tetrameric SOSS1 complex. INTS6 binds to DNA:RNA hybrids and promotes Protein Phosphatase 2A (PP2A) recruitment to DSBs, facilitating the dephosphorylation of RNAPII. Furthermore, INTS6 prevents the accumulation of damage-associated RNA transcripts (DARTs) and the stabilization of DNA:RNA hybrids at DSB sites. INTS6 interacts with and promotes the recruitment of senataxin (SETX) to DSBs, facilitating the resolution of DNA:RNA hybrids/R-loops. Our results underscore the significance of the tetrameric SOSS1 complex in the autoregulation of DNA:RNA hybrids and efficient DNA repair.

• MeSH
• DNA vazebné proteiny metabolismus   MeSH
• DNA-helikasy metabolismus   genetika   MeSH
• DNA * metabolismus   chemie   MeSH
• dvouřetězcové zlomy DNA * MeSH
• fosforylace MeSH
• homeostáza genetika   MeSH
• lidé MeSH
• oprava DNA * MeSH
• proteinfosfatasa 2 metabolismus   genetika   MeSH
• R-smyčka MeSH
• RNA-helikasy metabolismus   genetika   MeSH
• RNA-polymerasa II * metabolismus   MeSH
• RNA * metabolismus   genetika   chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA vazebné proteiny MeSH
• DNA-helikasy MeSH
• DNA * MeSH
• proteinfosfatasa 2 MeSH
• RNA-helikasy MeSH
• RNA-polymerasa II * MeSH
• RNA * MeSH

Combined inhibition of oxidative phosphorylation (OXPHOS) and glycolysis has been shown to activate a PP2A-dependent signaling pathway, leading to tumor cell death. Here, we analyze highly selective mitochondrial complex I or III inhibitors in vitro and in vivo to elucidate the molecular mechanisms leading to cell death following OXPHOS inhibition. We show that IACS-010759 treatment (complex I inhibitor) induces a reactive oxygen species (ROS)-dependent dissociation of CIP2A from PP2A, leading to its destabilization and degradation through chaperone-mediated autophagy. Mitochondrial complex III inhibition has analogous effects. We establish that activation of the PP2A holoenzyme containing B56δ regulatory subunit selectively mediates tumor cell death, while the arrest in proliferation that is observed upon IACS-010759 treatment does not depend on the PP2A-B56δ complex. These studies provide a molecular characterization of the events subsequent to the alteration of critical bioenergetic pathways and help to refine clinical studies aimed to exploit metabolic vulnerabilities of tumor cells.

• Klíčová slova
• CIP2A, CP: Cancer, CP: Molecular biology, OXPHOS, PP2A, cancer, chaperone-mediated autophagy, fasting, glycolysis, metabolism,
• MeSH
• autoantigeny metabolismus   MeSH
• autofagie zprostředkovaná chaperony * MeSH
• energetický metabolismus MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádory * patologie   MeSH
• oxidativní fosforylace MeSH
• proteinfosfatasa 2 antagonisté a inhibitory   metabolismus   MeSH
• respirační komplex I * antagonisté a inhibitory   MeSH
• signální transdukce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• autoantigeny MeSH
• CIP2A protein, human MeSH Prohlížeč
• proteinfosfatasa 2 MeSH
• respirační komplex I * MeSH

Plants, like other multicellular organisms, survive through a delicate balance between growth and defense against pathogens. Salicylic acid (SA) is a major defense signal in plants, and the perception mechanism as well as downstream signaling activating the immune response are known. Here, we identify a parallel SA signaling that mediates growth attenuation. SA directly binds to A subunits of protein phosphatase 2A (PP2A), inhibiting activity of this complex. Among PP2A targets, the PIN2 auxin transporter is hyperphosphorylated in response to SA, leading to changed activity of this important growth regulator. Accordingly, auxin transport and auxin-mediated root development, including growth, gravitropic response, and lateral root organogenesis, are inhibited. This study reveals how SA, besides activating immunity, concomitantly attenuates growth through crosstalk with the auxin distribution network. Further analysis of this dual role of SA and characterization of additional SA-regulated PP2A targets will provide further insights into mechanisms maintaining a balance between growth and defense.

• Klíčová slova
• NPR1, PIN, PP2A, auxin, auxin transport, gravitropism, immunity, phosphorylation, protein phosphatase 2A, salicylic acid,
• MeSH
• Arabidopsis růst a vývoj   fyziologie   MeSH
• imunita rostlin MeSH
• kořeny rostlin růst a vývoj   metabolismus   MeSH
• kyselina salicylová metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• proteinfosfatasa 2 metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• signální transdukce * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyselina salicylová MeSH
• kyseliny indoloctové MeSH
• PIN2 protein, Arabidopsis MeSH Prohlížeč
• PP2A protein, Arabidopsis MeSH Prohlížeč
• proteinfosfatasa 2 MeSH
• proteiny huseníčku MeSH

The phytohormone auxin is a major determinant and regulatory component important for plant development. Auxin transport between cells is mediated by a complex system of transporters such as AUX1/LAX, PIN, and ABCB proteins, and their localization and activity is thought to be influenced by phosphatases and kinases. Flavonols have been shown to alter auxin transport activity and changes in flavonol accumulation in the Arabidopsis thaliana rol1-2 mutant cause defects in auxin transport and seedling development. A new mutation in ROOTS CURL IN NPA 1 (RCN1), encoding a regulatory subunit of the phosphatase PP2A, was found to suppress the growth defects of rol1-2 without changing the flavonol content. rol1-2 rcn1-3 double mutants show wild type-like auxin transport activity while levels of free auxin are not affected by rcn1-3. In the rol1-2 mutant, PIN2 shows a flavonol-induced basal-to-apical shift in polar localization which is reversed in the rol1-2 rcn1-3 to basal localization. In vivo analysis of PINOID action, a kinase known to influence PIN protein localization in a PP2A-antagonistic manner, revealed a negative impact of flavonols on PINOID activity. Together, these data suggest that flavonols affect auxin transport by modifying the antagonistic kinase/phosphatase equilibrium.

• MeSH
• Arabidopsis účinky léků   genetika   metabolismus   MeSH
• flavonoidy farmakologie   MeSH
• glukosyltransferasy genetika   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• mutace MeSH
• proteinfosfatasa 2 genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 3-hydroxyflavone MeSH Prohlížeč
• flavonoidy MeSH
• glukosyltransferasy MeSH
• kyseliny indoloctové MeSH
• PIN2 protein, Arabidopsis MeSH Prohlížeč
• proteinfosfatasa 2 MeSH
• proteiny huseníčku MeSH
• RCN1 protein, Arabidopsis MeSH Prohlížeč
• RHM1 protein, Arabidopsis MeSH Prohlížeč

The non-dioxin-like environmental toxicant 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153), member of a group of persistent organic pollutants wide-spread throughout the environment, reduces gap junction intercellular communication (GJIC), an event possibly associated with tumor promotion. Since very few studies have investigated the signaling effectors and mode(s) of action of PCB153, and it is known that the gap junction (GJ) protein Cx43 can be regulated by the bioactive sphingolipid (SL) sphingosine 1-phosphate (S1P), this in vitro study mainly addresses whether SL metabolism is affected by PCB153 in rat liver epithelial WB-F344 cells. PCB153 treatment obtained significant changes in the S1P/ceramide (Cer) ratio, known to be crucial in determining cell fate. In particular, an increase in S1P at 30 min and a decrease of the bioactive lipid at 3 h were observed, whereas Cer level increased at 1 h and 24 h. Notably, a time-dependent modulation of sphingosine kinase (SphK), the enzyme responsible for S1P synthesis, and of its regulators, ERK1/2 and protein phosphatase PP2A, supports the involvement of these signaling effectors in PCB153 toxicity. Electrophysiological analyses, furthermore, indicated that the lipophilic environmental toxicant significantly reduced GJ biophysical properties, affecting both voltage-dependent (such as those formed by Cx43 and/or Cx32) and voltage-independent channels, thereby demonstrating that PCB153 may act differently on GJs formed by distinct Cx isoforms. SphK down-regulation alone induced GJIC impairment, and, when combined with PCB153, the acute effect on GJ suppression was additive. Moreover, after enzyme-specific gene silencing, the SphK1 isoform appears to be responsible for down-regulating Cx43 expression, while being the target of PCB153 at short-term exposure. In conclusion, we provide the first evidence of novel effectors in PCB153 toxic action in rat liver stem-like cells, leading us to consider SLs as potential markers for preventing GJIC deregulation and, thus, the tumorigenic action elicited by this environmental toxicant.

• Klíčová slova
• Connexin 43, Environmental toxicant non-dioxin-like PCB153, Gap junctions, PP2A, Sphingosine-1-phosphate,
• MeSH
• dioxiny toxicita   MeSH
• elektrofyziologie metody   MeSH
• fosfotransferasy s alkoholovou skupinou jako akceptorem antagonisté a inhibitory   genetika   metabolismus   MeSH
• játra cytologie   účinky léků   MeSH
• konexin 43 metabolismus   MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• lysofosfolipidy metabolismus   MeSH
• mezerový spoj účinky léků   fyziologie   MeSH
• mitogenem aktivovaná proteinkinasa 3 metabolismus   MeSH
• polychlorované bifenyly toxicita   MeSH
• proteinfosfatasa 2 genetika   metabolismus   MeSH
• sfingolipidy metabolismus   MeSH
• sfingosin analogy a deriváty   metabolismus   MeSH
• signální transdukce účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 2,4,5,2',4',5'-hexachlorobiphenyl MeSH Prohlížeč
• dioxiny MeSH
• fosfotransferasy s alkoholovou skupinou jako akceptorem MeSH
• Gja1 protein, rat MeSH Prohlížeč
• konexin 43 MeSH
• lysofosfolipidy MeSH
• mitogenem aktivovaná proteinkinasa 3 MeSH
• polychlorované bifenyly MeSH
• proteinfosfatasa 2 MeSH
• sfingolipidy MeSH
• sfingosin MeSH
• sphingosine 1-phosphate MeSH Prohlížeč
• sphingosine kinase MeSH Prohlížeč

Modulation of Ca(2+) homoeostasis in cardiac myocytes plays a major role in beat-to-beat regulation of heart function. Previous studies suggest that sphingosine-1-phosphate (S1P), a biologically active sphingomyelin metabolite, regulates Ca(2+) handling in cardiac myocytes, but the underlying mechanism is unclear. In the present study, we tested the hypothesis that S1P-induced functional alteration of intracellular Ca(2+) handling includes the L-type calcium channel current (ICa,L) via a signalling pathway involving P21-activated kinase 1 (Pak1). Our results show that, in rat ventricular myocytes, S1P (100 nM) does not affect the basal activity of ICa,L but is able to partially reverse the effect of the β-adrenergic agonist Isoproterenol (ISO, 100 nM) on ICa,L. S1P (25 nM) also significantly prevents ISO (5 nM)-induced Ca(2+) waves and diastolic Ca(2+) release in these cells. Our further molecular characterisation demonstrates that Pak1 activity is increased in myocytes treated with S1P (25 nM) compared with those myocytes without treatment of S1P. By immunoprecipitation we demonstrate that Pak1 and protein phosphatase 2A (PP2A) are associated in ventricular tissue indicating their functional interaction. Thus the results indicate that S1P attenuates β-adrenergic stress-induced alteration of intracellular Ca(2+) release and L-type Ca(2+) channel current at least in part via Pak1-PP2A-mediated signalling.

• Klíčová slova
• L-type calcium current, ICa,L, P21-activated kinase 1, Pak1, Sphingosine-1-phosphate, S1P,
• MeSH
• intracelulární signální peptidy a proteiny metabolismus   MeSH
• kardiomyocyty metabolismus   MeSH
• krysa rodu Rattus MeSH
• lysofosfolipidy farmakologie   MeSH
• proteinfosfatasa 2 metabolismus   MeSH
• sfingosin analogy a deriváty   farmakologie   MeSH
• srdeční komory metabolismus   MeSH
• vápník metabolismus   MeSH
• vápníková signalizace účinky léků   MeSH
• vápníkové kanály - typ L metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• intracelulární signální peptidy a proteiny MeSH
• lysofosfolipidy MeSH
• PAK1IP1 protein, human MeSH Prohlížeč
• Ppp2ca protein, rat MeSH Prohlížeč
• proteinfosfatasa 2 MeSH
• sfingosin MeSH
• sphingosine 1-phosphate MeSH Prohlížeč
• vápník MeSH
• vápníkové kanály - typ L MeSH

The shaping of organs in plants depends on the intercellular flow of the phytohormone auxin, of which the directional signaling is determined by the polar subcellular localization of PIN-FORMED (PIN) auxin transport proteins. Phosphorylation dynamics of PIN proteins are affected by the protein phosphatase 2A (PP2A) and the PINOID kinase, which act antagonistically to mediate their apical-basal polar delivery. Here, we identified the ROTUNDA3 (RON3) protein as a regulator of the PP2A phosphatase activity in Arabidopsis thaliana. The RON3 gene was map-based cloned starting from the ron3-1 leaf mutant and found to be a unique, plant-specific gene coding for a protein with high and dispersed proline content. The ron3-1 and ron3-2 mutant phenotypes [i.e., reduced apical dominance, primary root length, lateral root emergence, and growth; increased ectopic stages II, IV, and V lateral root primordia; decreased auxin maxima in indole-3-acetic acid (IAA)-treated root apical meristems; hypergravitropic root growth and response; increased IAA levels in shoot apices; and reduced auxin accumulation in root meristems] support a role for RON3 in auxin biology. The affinity-purified PP2A complex with RON3 as bait suggested that RON3 might act in PIN transporter trafficking. Indeed, pharmacological interference with vesicle trafficking processes revealed that single ron3-2 and double ron3-2 rcn1 mutants have altered PIN polarity and endocytosis in specific cells. Our data indicate that RON3 contributes to auxin-mediated development by playing a role in PIN recycling and polarity establishment through regulation of the PP2A complex activity.

• Klíčová slova
• Arabidopsis, PIN recycling, PP2A, auxin, plant development,
• MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   MeSH
• biologické modely MeSH
• geneticky modifikované rostliny MeSH
• hybridizace in situ MeSH
• konfokální mikroskopie MeSH
• kořeny rostlin genetika   růst a vývoj   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• listy rostlin genetika   růst a vývoj   metabolismus   MeSH
• membránové transportní proteiny genetika   metabolismus   MeSH
• mutace MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• proteinfosfatasa 2 metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny indoloctové MeSH
• membránové transportní proteiny MeSH
• PIN1 protein, Arabidopsis MeSH Prohlížeč
• proteinfosfatasa 2 MeSH
• proteiny huseníčku MeSH
• RON3 protein, Arabidopsis MeSH Prohlížeč

Microcystins (MCs) are primarily hepatotoxins produced by cyanobacteria and are responsible for intoxication in humans and animals. There are many incidents of chronic exposure to MCs, which have been attributed to the inappropriate treatment of water supplies or contaminated food. Using RAW 264.7 macrophages, we showed the potency of microcystin-LR (MC-LR) to stimulate production of pro-inflammatory cytokines (tumor necrosis factor α and interleukin-6) as a consequence of fast nuclear factor κB and nitrogen-activated protein kinase activation. In contrast to other studies, the observed effects were not attributed to the intracellular inhibition of protein phosphatases 1/2A due to lack of specific transmembrane transporters for MCs. However, the MC-LR-induced activation of macrophages was effectively inhibited by a specific peptide that blocks signaling of receptors, which play a pivotal role in the innate immune responses. Taken together, we showed for the first time that MC-LR could interfere with macrophage receptors that are responsible for triggering the above-mentioned signaling pathways. These findings provide an interesting mechanistic explanation of some adverse health outcomes associated with toxic cyanobacteria and MCs.

• MeSH
• buněčné linie účinky léků   MeSH
• chemické látky znečišťující vodu toxicita   MeSH
• imunologické faktory toxicita   MeSH
• interleukin-6 metabolismus   MeSH
• makrofágy účinky léků   metabolismus   patologie   MeSH
• mikrocystiny toxicita   MeSH
• mořské toxiny MeSH
• myši MeSH
• NF-kappa B metabolismus   MeSH
• přirozená imunita účinky léků   MeSH
• proteinfosfatasa 2 metabolismus   MeSH
• sinice patogenita   MeSH
• testy chronické toxicity metody   MeSH
• TNF-alfa metabolismus   MeSH
• zánět chemicky indukované   imunologie   metabolismus   MeSH
• zásobování vodou MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chemické látky znečišťující vodu MeSH
• cyanoginosin LR MeSH Prohlížeč
• imunologické faktory MeSH
• interleukin-6, mouse MeSH Prohlížeč
• interleukin-6 MeSH
• mikrocystiny MeSH
• mořské toxiny MeSH
• NF-kappa B MeSH
• proteinfosfatasa 2 MeSH
• TNF-alfa MeSH

• MeSH
• endopeptidasy metabolismus   MeSH
• fosforylace MeSH
• kaseinkinasa I antagonisté a inhibitory   metabolismus   MeSH
• lidé MeSH
• meióza MeSH
• proteinfosfatasa 2 metabolismus   MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• segregace chromozomů MeSH
• separasa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• zprávy MeSH
• Názvy látek
• endopeptidasy MeSH
• kaseinkinasa I MeSH
• proteinfosfatasa 2 MeSH
• proteiny buněčného cyklu MeSH
• REC8 protein, human MeSH Prohlížeč
• separasa MeSH
• SGO1 protein, human MeSH Prohlížeč