The development of metastasis is a leading cause of cancer-related death that involves specific changes in the plasma membrane (PM) and nucleus of cancer cells. Elevated levels of membrane lipids, including sphingomyelin, cholesterol, and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), in the PM, contribute to changes in membrane rigidity, lipid raft formation, and actin polymerisation dynamics, processes that drive cell invasion. This review discusses the relationship between well-studied cytoplasmic phosphoinositides and their lesser-known nuclear counterparts, highlighting their functional role in metastatic progression. Nuclear phosphoinositides, particularly PI(4,5)P2, are essential for regulating transcription factors and chromatin organisation, thereby shaping gene expression patterns. We also explore the role of PI(4,5)P2 and its metabolism in cancer cell invasiveness and metastasis, proposing a model in which the dysregulation of cytosolic and/or nuclear PI(4,5)P2 pool triggers malignant transformation. Understanding the PI(4,5)P2-related mechanisms underlying metastasis may provide insights into potential therapeutic targets, paving the way for more effective therapies and improved patient outcomes.
- Klíčová slova
- Biocondensates, Cancer, HPV, Metastasis, Nucleus, Phosphatidylinositol 4,5-bisphosphate,
- MeSH
- buněčná membrána * metabolismus MeSH
- buněčné jádro * metabolismus MeSH
- fosfatidylinositol-4,5-difosfát * metabolismus genetika MeSH
- lidé MeSH
- membránové mikrodomény metabolismus MeSH
- metastázy nádorů MeSH
- nádory * metabolismus patologie genetika MeSH
- signální transdukce MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- fosfatidylinositol-4,5-difosfát * MeSH
The liquid-liquid phase separation in the cell nucleus regulates various processes such as gene regulation and transcription control, chromatin organization, and DNA repair. A plethora of proteins and RNAs contribute to the formation of biomolecular condensates and recently, several nuclear phosphoinositides were shown to be a part of these membrane-less complexes within the nucleus as well. Here we lipid-interacting RNA sequencing (LIPRNAseq) and confocal microscopy to uncover the RNA-binding capacity and localization of phosphatidylinositol 4,5 bisphosphate (PIP2). We discovered the consensus PIP2-binding AU-rich RNA motif and identified long non-coding RNA HANR (lncHANR) to colocalize with PIP2 in the proximity to the nucleolus in the perinucleolar compartment (PNC). Colocalization studies with different nuclear markers reveal that PIP2-HANR presence in the PNC correlates with oncogenic super-enhancers, and both PNC and oncogenic enhancers are part of the same structure. As lncHANR, PNC, and oncogenic super-enhancers are associated with cancer cell lines and tumors, we suggest that they can serve as interchangeable prognostic markers. Understanding of the interplay between lipid metabolism, and lncRNAs in subnuclear compartment phase separation can lead to future improvement in treatment strategies and personalized cancer management approaches.
- Klíčová slova
- HANR, Long non-coding RNA, Oncogenic super-enhancers, PIP2, PNC, Perinucleolar compartment, Phase separation, Phosphatidylinositol 4,5-bisphosphate,
- MeSH
- buněčné jadérko * metabolismus genetika MeSH
- fosfatidylinositol-4,5-difosfát * metabolismus genetika MeSH
- lidé MeSH
- nádory * genetika metabolismus patologie MeSH
- RNA dlouhá nekódující * genetika metabolismus MeSH
- zesilovače transkripce * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- fosfatidylinositol-4,5-difosfát * MeSH
- RNA dlouhá nekódující * MeSH
The RNA content is crucial for the formation of nuclear compartments, such as nuclear speckles and nucleoli. Phosphatidylinositol 4,5-bisphosphate (PIP2) is found in nuclear speckles, nucleoli, and nuclear lipid islets and is involved in RNA polymerase I/II transcription. Intriguingly, the nuclear localization of PIP2 was also shown to be RNA-dependent. We therefore investigated whether PIP2 and RNA cooperate in the establishment of nuclear architecture. In this study, we unveiled the RNA-dependent PIP2-associated (RDPA) nuclear proteome in human cells by mass spectrometry. We found that intrinsically disordered regions (IDRs) with polybasic PIP2-binding K/R motifs are prevalent features of RDPA proteins. Moreover, these IDRs of RDPA proteins exhibit enrichment for phosphorylation, acetylation, and ubiquitination sites. Our results show for the first time that the RDPA protein Bromodomain-containing protein 4 (BRD4) associates with PIP2 in the RNA-dependent manner via electrostatic interactions, and that altered PIP2 levels affect the number of nuclear foci of BRD4 protein. Thus, we propose that PIP2 spatiotemporally orchestrates nuclear processes through association with RNA and RDPA proteins and affects their ability to form foci presumably via phase separation. This suggests the pivotal role of PIP2 in the establishment of a functional nuclear architecture competent for gene expression.
- MeSH
- buněčné jádro * metabolismus genetika MeSH
- fosfatidylinositol-4,5-difosfát * metabolismus MeSH
- fosforylace MeSH
- jaderné proteiny * metabolismus genetika MeSH
- lidé MeSH
- proteiny buněčného cyklu metabolismus genetika MeSH
- proteiny obsahující bromodoménu MeSH
- RNA metabolismus genetika MeSH
- transkripční faktory * metabolismus genetika MeSH
- vazba proteinů MeSH
- vnitřně neuspořádané proteiny * metabolismus genetika chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- BRD4 protein, human MeSH Prohlížeč
- fosfatidylinositol-4,5-difosfát * MeSH
- jaderné proteiny * MeSH
- proteiny buněčného cyklu MeSH
- proteiny obsahující bromodoménu MeSH
- RNA MeSH
- transkripční faktory * MeSH
- vnitřně neuspořádané proteiny * MeSH
Homeostasis of cellular membranes is maintained by fine-tuning their lipid composition. Yeast lipid transporter Osh6, belonging to the oxysterol-binding protein-related proteins family, was found to participate in the transport of phosphatidylserine (PS). PS synthesized in the endoplasmic reticulum is delivered to the plasma membrane, where it is exchanged for phosphatidylinositol 4-phosphate (PI4P). PI4P provides the driving force for the directed PS transport against its concentration gradient. In this study, we employed an in vitro approach to reconstitute the transport process into the minimalistic system of large unilamellar vesicles to reveal its fundamental biophysical determinants. Our study draws a comprehensive portrait of the interplay between the structure and dynamics of Osh6, the carried cargo lipid, and the physical properties of the involved membranes, with particular attention to the presence of charged lipids and to membrane fluidity. Specifically, we address the role of the cargo lipid, which, by occupying the transporter, imposes changes in its dynamics and, consequently, predisposes the cargo to disembark in the correct target membrane.
- MeSH
- biologický transport MeSH
- buněčná membrána * metabolismus MeSH
- fluidita membrány MeSH
- fosfatidylinositolfosfáty metabolismus MeSH
- fosfatidylseriny metabolismus MeSH
- proteiny vázající oxysterol MeSH
- Saccharomyces cerevisiae - proteiny * metabolismus genetika MeSH
- Saccharomyces cerevisiae metabolismus MeSH
- steroidní receptory metabolismus MeSH
- unilamelární lipozómy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fosfatidylinositolfosfáty MeSH
- fosfatidylseriny MeSH
- phosphatidylinositol 4-phosphate MeSH Prohlížeč
- proteiny vázající oxysterol MeSH
- Saccharomyces cerevisiae - proteiny * MeSH
- steroidní receptory MeSH
- unilamelární lipozómy MeSH
Phosphatidylinositol phosphates are powerful signaling molecules that orchestrate signaling and direct membrane trafficking in the cytosol. Interestingly, phosphatidylinositol phosphates also localize within the membrane-less compartments of the cell nucleus, where they participate in the regulation of gene expression. Nevertheless, current models of gene expression, which include condensates of proteins and nucleic acids, do not include nuclear phosphatidylinositol phosphates. This gap is partly a result of the missing detailed analysis of the subnuclear distribution of phosphatidylinositol phosphates and their relationships with gene expression. Here, we used quantitative dual-color direct stochastic optical reconstruction microscopy to analyze the nanoscale co-patterning between RNA polymerase II transcription initiation and elongation markers with respect to phosphatidylinositol 4,5- or 3,4-bisphosphate in the nucleoplasm and nuclear speckles and compared it with randomized data and cells with inhibited transcription. We found specific co-patterning of the transcription initiation marker P-S5 with phosphatidylinositol 4,5-bisphosphate in the nucleoplasm and with phosphatidylinositol 3,4-bisphosphate at the periphery of nuclear speckles. We showed the specific accumulation of the transcription elongation marker PS-2 and of nascent RNA in the proximity of phosphatidylinositol 3,4-bisphosphate associated with nuclear speckles. Taken together, this shows that the distinct spatial associations between the consecutive stages of RNA polymerase II transcription and nuclear phosphatidylinositol phosphates exhibit specificity within the gene expression compartments. Thus, in analogy to the cellular membranes, where phospholipid composition orchestrates signaling pathways and directs membrane trafficking, we propose a model in which the phospholipid identity of gene expression compartments orchestrates RNA polymerase II transcription.
- Klíčová slova
- gene expression, nuclear architecture, nuclear speckles, nucleoplasm, quantitative direct stochastic optical reconstruction microscopy dSTORM,
- MeSH
- buněčné jádro * metabolismus MeSH
- fosfatidylinositol-4,5-difosfát * metabolismus MeSH
- fosfatidylinositolfosfáty metabolismus MeSH
- genetická transkripce * MeSH
- HeLa buňky MeSH
- lidé MeSH
- RNA-polymerasa II * metabolismus genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fosfatidylinositol-4,5-difosfát * MeSH
- fosfatidylinositolfosfáty MeSH
- RNA-polymerasa II * MeSH
Phosphatidylinositol (PI) is the precursor lipid for the minor phosphoinositides (PPIns), which are critical for multiple functions in all eukaryotic cells. It is poorly understood how phosphatidylinositol, which is synthesized in the ER, reaches those membranes where PPIns are formed. Here, we used VT01454, a recently identified inhibitor of class I PI transfer proteins (PITPs), to unravel their roles in lipid metabolism, and solved the structure of inhibitor-bound PITPNA to gain insight into the mode of inhibition. We found that class I PITPs not only distribute PI for PPIns production in various organelles such as the plasma membrane (PM) and late endosomes/lysosomes, but that their inhibition also significantly reduced the levels of phosphatidylserine, di- and triacylglycerols, and other lipids, and caused prominent increases in phosphatidic acid. While VT01454 did not inhibit Golgi PI4P formation nor reduce resting PM PI(4,5)P2 levels, the recovery of the PM pool of PI(4,5)P2 after receptor-mediated hydrolysis required both class I and class II PITPs. Overall, these studies show that class I PITPs differentially regulate phosphoinositide pools and affect the overall cellular lipid landscape.
- Klíčová slova
- Golgi Complex, Membrane Contact Sites, Non-Vesicular Lipid Transport, Phosphatidylinositol, Phospholipase C,
- MeSH
- buněčná membrána metabolismus MeSH
- endozomy metabolismus MeSH
- fosfatidylinositoly * metabolismus MeSH
- HeLa buňky MeSH
- lidé MeSH
- metabolismus lipidů MeSH
- organely metabolismus MeSH
- proteiny přenášející fosfolipidy * metabolismus genetika MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
FGF2 is a cell survival factor involved in tumor-induced angiogenesis that is secreted through an unconventional secretory pathway based upon direct protein translocation across the plasma membrane. Here, we demonstrate that both PI(4,5)P2-dependent FGF2 recruitment at the inner plasma membrane leaflet and FGF2 membrane translocation into the extracellular space are positively modulated by cholesterol in living cells. We further revealed cholesterol to enhance FGF2 binding to PI(4,5)P2-containing lipid bilayers. Based on extensive atomistic molecular dynamics (MD) simulations and membrane tension experiments, we proposed cholesterol to modulate FGF2 binding to PI(4,5)P2 by (i) increasing head group visibility of PI(4,5)P2 on the membrane surface, (ii) increasing avidity by cholesterol-induced clustering of PI(4,5)P2 molecules triggering FGF2 oligomerization, and (iii) increasing membrane tension facilitating the formation of lipidic membrane pores. Our findings have general implications for phosphoinositide-dependent protein recruitment to membranes and explain the highly selective targeting of FGF2 toward the plasma membrane, the subcellular site of FGF2 membrane translocation during unconventional secretion of FGF2.
- MeSH
- buněčná membrána metabolismus MeSH
- cholesterol * metabolismus MeSH
- fibroblastový růstový faktor 2 * metabolismus MeSH
- fosfatidylinositol-4,5-difosfát * metabolismus MeSH
- lipidové dvojvrstvy * metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cholesterol * MeSH
- fibroblastový růstový faktor 2 * MeSH
- fosfatidylinositol-4,5-difosfát * MeSH
- lipidové dvojvrstvy * MeSH
An aerobic, Gram-stain-positive and non-spore-forming strain, designated C1-1T, was isolated from a fellfield soil sample collected from frost-sorted polygons on Jane Col, Signy Island, Maritime Antarctic. Cells with a size of 0.65-0.9×1.2-1.7 µm have a flagellar motile apparatus and exhibit a rod-coccus growth cycle. Optimal growth conditions were observed at 15-20 °C, pH 7.0 and NaCl concentration up to 0.5 % (w/v) in the medium. The 16S rRNA gene sequence of C1-1T showed the highest pairwise similarity of 98.77 % to Arthrobacter glacialis NBRC 113092T. Phylogenetic trees based on the 16S rRNA and whole-genome sequences revealed that strain C1-1T belongs to the genus Arthrobacter and is most closely related to members of the 'Arthrobacter psychrolactophilus group'. The G+C content of genomic DNA was 58.95 mol%. The original and orthologous average nucleotide identities between strain C1-1T and A. glacialis NBRC 113092T were 77.15 % and 77.38 %, respectively. The digital DNA-DNA relatedness values between strain C1-1T and A. glacialis NBRC 113092T was 21.6 %. The polar lipid profile was composed mainly of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified glycolipid. The predominant cellular fatty acids were anteiso-C15 : 0 (75 %) and anteiso-C17 : 0 (15.2 %). Menaquinone MK-9(H2) (86.4 %) was the major respiratory quinone in strain C1-1T. The peptidoglycan type was determined as A3α (l-Lys-l-Ala3; A11.6). Based on all described phylogenetic, physiological and chemotaxonomic characteristics, we propose that strain C1-1T (=DSM 112353T=CCM 9148T) is the type strain of a novel species Arthrobacter polaris sp. nov.
- Klíčová slova
- Antarctica, Arthrobacter, Micrococcaceae, cold-adapted microorganisms, whole-genome sequencing,
- MeSH
- Arthrobacter * MeSH
- chlorid sodný MeSH
- DNA bakterií genetika MeSH
- fosfatidylinositoly MeSH
- fosfolipidy chemie MeSH
- fylogeneze MeSH
- glykolipidy chemie MeSH
- hybridizace nukleových kyselin MeSH
- kardiolipiny MeSH
- mastné kyseliny chemie MeSH
- Micrococcaceae * MeSH
- nukleotidy MeSH
- peptidoglykan chemie MeSH
- půda MeSH
- RNA ribozomální 16S genetika MeSH
- sekvenční analýza DNA MeSH
- techniky typizace bakterií MeSH
- vitamin K 2 chemie MeSH
- zastoupení bazí MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Antarktida MeSH
- Názvy látek
- chlorid sodný MeSH
- DNA bakterií MeSH
- fosfatidylinositoly MeSH
- fosfolipidy MeSH
- glykolipidy MeSH
- kardiolipiny MeSH
- mastné kyseliny MeSH
- menaquinone 9 MeSH Prohlížeč
- nukleotidy MeSH
- peptidoglykan MeSH
- půda MeSH
- RNA ribozomální 16S MeSH
- vitamin K 2 MeSH
Phosphatidylinositol 4-kinases (PI4Ks) are the first enzymes that commit phosphatidylinositol into the phosphoinositide pathway. Here, we show that Arabidopsis thaliana seedlings deficient in PI4Kβ1 and β2 have several developmental defects including shorter roots and unfinished cytokinesis. The pi4kβ1β2 double mutant was insensitive to exogenous auxin concerning inhibition of root length and cell elongation; it also responded more slowly to gravistimulation. The pi4kß1ß2 root transcriptome displayed some similarities to a wild type plant response to auxin. Yet, not all the genes displayed such a constitutive auxin-like response. Besides, most assessed genes did not respond to exogenous auxin. This is consistent with data with the transcriptional reporter DR5-GUS. The content of bioactive auxin in the pi4kß1ß2 roots was similar to that in wild-type ones. Yet, an enhanced auxin-conjugating activity was detected and the auxin level reporter DII-VENUS did not respond to exogenous auxin in pi4kß1ß2 mutant. The mutant exhibited altered subcellular trafficking behavior including the trapping of PIN-FORMED 2 protein in rapidly moving vesicles. Bigger and less fragmented vacuoles were observed in pi4kß1ß2 roots when compared to the wild type. Furthermore, the actin filament web of the pi4kß1ß2 double mutant was less dense than in wild-type seedling roots, and less prone to rebuilding after treatment with latrunculin B. A mechanistic model is proposed in which an altered PI4K activity leads to actin filament disorganization, changes in vesicle trafficking, and altered auxin homeostasis and response resulting in a pleiotropic root phenotypes.
- MeSH
- Arabidopsis * metabolismus MeSH
- fosfatidylinositolfosfáty MeSH
- fosfatidylinositoly metabolismus MeSH
- kořeny rostlin genetika metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- fosfatidylinositolfosfáty MeSH
- fosfatidylinositoly MeSH
- kyseliny indoloctové MeSH
- phosphatidylinositol 4-phosphate MeSH Prohlížeč
- proteiny huseníčku * MeSH
Pollen tubes require a tightly regulated pectin secretion machinery to sustain the cell wall plasticity required for polar tip growth. Involved in this regulation at the apical plasma membrane are proteins and signaling molecules, including phosphoinositides and phosphatidic acid (PA). However, the contribution of diacylglycerol kinases (DGKs) is not clear. We transiently expressed tobacco DGKs in pollen tubes to identify a plasma membrane (PM)-localized isoform, and then to study its effect on pollen tube growth, pectin secretion and lipid signaling. In order to potentially downregulate DGK5 function, we overexpressed an inactive variant. Only one of eight DGKs displayed a confined localization at the apical PM. We could demonstrate its enzymatic activity and that a kinase-dead variant was inactive. Overexpression of either variant led to differential perturbations including misregulation of pectin secretion. One mode of regulation could be that DGK5-formed PA regulates phosphatidylinositol 4-phosphate 5-kinases, as overexpression of the inactive DGK5 variant not only led to a reduction of PA but also of phosphatidylinositol 4,5-bisphosphate levels and suppressed related growth phenotypes. We conclude that DGK5 is an additional player of polar tip growth that regulates pectin secretion probably in a common pathway with PI4P 5-kinases.
- Klíčová slova
- diacylglycerol kinase, lipid signaling, pectin, phosphatidic acid, pollen tube, secretion, tobacco (Nicotiana tabacum),
- MeSH
- buněčná membrána metabolismus MeSH
- diacylglycerolkinasa genetika metabolismus MeSH
- fosfatidylinositoly metabolismus MeSH
- pylová láčka * MeSH
- tabák * metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- diacylglycerolkinasa MeSH
- fosfatidylinositoly MeSH