Biology subjects

Cysewski, D.

Publications and source records attributed to Cysewski, D..

16 recordsLinked to original sources

bioRxiv2026

RNA length and receptor usage define innate immune recognition across species.

Recognition of viral double-stranded RNA (dsRNA) is a central trigger of innate antiviral immunity, yet the role of RNA length in shaping immune sensing across species remains poorly defined. Here, we identify RNA length as a key determinant of innate immune activation and demonstrate that this parameter is differentially tuned across vertebrate hosts. Using defined dsRNA molecules, we compared immune responses in human, duck, and chicken cells. Short 5-triphosphorylated dsRNAs, including influenza-derived mini viral RNAs, robustly activated antiviral responses in human and duck cells but failed to do so in chicken cells. In contrast, longer dsRNAs induced immune activation across all species, revealing a species-specific threshold for dsRNA recognition. Mechanistically, this threshold is defined by differential engagement of RNA sensors. In human cells, sensing of short and intermediate dsRNA is strictly dependent on RIG-I, whereas in chicken cells, which lack RIG-I, MDA5 mediates dsRNA recognition and imposes a higher length requirement for activation. Consistent with this, duck cells, which retain RIG-I, respond to short dsRNA similarly to human cells. These differences in dsRNA sensing are accompanied by differential activation of downstream antiviral pathways, including PKR-dependent translational control and OAS/RNase L activation. Together, our findings identify RNA length as a fundamental parameter governing innate immune recognition and reveal that species-specific usage of RNA sensors constrains antiviral sensing, with implications for host susceptibility and virus-host interactions. Significance StatementRecognition of viral RNA is central to antiviral immunity, yet the rules governing which viral RNAs are sensed across species remain poorly understood. Here, we show that RNA length defines a species-specific threshold for innate immune recognition. Human and duck cells efficiently detect short viral double-stranded RNAs generated during influenza infection, whereas chicken cells respond only to substantially longer RNA duplexes. Mechanistically, this difference reflects the usage of distinct antiviral RNA sensors: RIG-I enables sensing of short viral RNAs, while MDA5 imposes a higher length requirement for activation. Our findings reveal that host species differ in the spectrum of viral RNA ligands accessible to immune detection, providing a framework for understanding species-specific antiviral responses and host susceptibility.

microbiology↗

bioRxiv2026

The RNA helicase DDX53 (CAGE) contributes to RNA metabolism in a human germ cell model

DDX53 (DEAD-box helicase 53, known also as CAGE) is an intronless gene on the X chromosome, which expression shows strong testis specificity. It belongs to the group of cancer-testis (CT) antigens, with most studies to date focusing on its role in cancer, but the precise biological function of DDX53 remains unclear. Previous reports identifying rare DDX53 variants in infertile men provided the rationale for investigating the role of DDX53 in the context of human spermatogenesis. By using the human seminoma cell line (TCam-2) as an in vitro male germline model, we aimed to investigate the function and molecular targets of DDX53 protein. Our eCLIP and RNA-seq data show that DDX53 protein directly interacts with numerous RNA molecules, drives transcriptome changes in human cells, and is involved in alternative splicing of RNA. Moreover, we identified potential DDX53 protein interactors using Co-IP-MS approach. Subcellular localization analysis by confocal microscopy indicated a predominantly cytoplasmic distribution of DDX53, with partial nuclear presence in TCam-2 cells. We also identified DDX53-positive structures that may correspond to germ granule-like assemblies, although their precise nature remains to be determined. Additionally, we confirmed DDX53 presence in human testis using a specific, commercially available anti-DDX53 antibody. Our data indicate that DDX53 protein acts as a regulator of RNA metabolism in human cells. Collectively, we show that DDX53 participates in transcriptome regulation (including splicing) in male germ cells and exhibits transcriptomewide RNA interactions, but its wider biological role remains to be clarified.

molecular biology↗

bioRxiv2025

Multi-omic screening identifies RBMXL3 as a primate-specific RNA-binding protein and candidate regulator of RNA metabolism in human spermatogenesis

BackgroundRBMXL3 is a primate-specific gene localized on the X chromosome, which expression is detectable mainly in the male gonad. So far, very little is known about the RBMXL3 protein function and its molecular interactions. However, recent reports mention the RBMXL3 gene in the context of human spermatogenesis, cancer, and a breathing disorder that affects newborns. In this study, we investigate the RBMXL3s molecular network on a genome-wide scale using the human seminoma cell line (TCam-2) as a male germline in vitro model. MethodsBy using transcriptomic (RNA sequencing (RNA-seq) and enhanced crosslinking and immunoprecipitation (eCLIP)) and proteomic (Co-immunoprecipitation coupled with Mass Spectrometry, (Co-IP-MS)) approaches we show RBMXL3 importance in RNA metabolism. Additionally, Western Blot, qRT-PCR, immunostaining, and confocal imaging were used in order to investigate the function of RBMXL3. Finally, we used a plasmid-based L1 retrotransposition assay to demonstrate the suppressive effect of RBMXL3 on human Long Interspersed Nuclear Element-1 (LINE-1, L1) retrotransposition. ResultsOur RNA-seq data show that RBMXL3 expression drives gene expression changes and influence alternative splicing in human cells. Moreover, by performing eCLIP we provide a proof that RBMXL3 binds to a wide range of RNA transcripts. Additionally, we confirmed the nuclear localization of RBMXL3 in TCam-2 cells and its presence in spermatogonia and spermatocytes within the human testis. Finally, we report for the first time that RBMXL3 restricts human LINE-1 retrotransposition. ConclusionsOur findings for the first time identify primate-specific RBMXL3 protein as a new upstream regulator of RNA metabolism, characterized by broad RNA-binding activity in human TCam-2 cells. Finally, we show that RBMXL3 expression heavily reduces LINE-1 retrotransposition in human cells, underlying RBMXL3 importance in maintaining genome integrity. Our data suggest that RBMXL3 may contribute to the regulation of transcriptome dynamics in male germ cells, while its broader functional implications remain to be determined. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=56 SRC="FIGDIR/small/677621v3_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@8bf116org.highwire.dtl.DTLVardef@180fe82org.highwire.dtl.DTLVardef@1c52960org.highwire.dtl.DTLVardef@11f7519_HPS_FORMAT_FIGEXP M_FIG C_FIG Created with BioRender.com

cell biology↗

bioRxiv2024

Profiling of yeast Saccharomyces cerevisiae mitochondrial AMPylome reveals a regulation of ATP synthase coupling trough subunit delta

The adenylation (AMPylation) of proteins as a posttranslational modification is used by bacteria during infection of host cells. These new virulence factors - AMPylases mainly belonging to the FIC domain containing proteins and constitute a potential drug target. Human FIC protein (HYPE) controls the activity of BiP chaperone under endoplasmic reticulum stress. No FIC family proteins have yet been identified in yeast Saccharomyces cerevisiae. The second family of AMPylases are SelO proteins which control the redox homeostasis in mitochondria and chloroplasts. We describe here the first global screening of AMPylated proteins in yeast S. cerevisiae mitochondrial proteome from wild type and SelO (Fmp40) lacking cells. Through quantitative mass-spectrometry-based proteomics, we identified a total of 169 AMPylated proteins in mitochondria while AMPylated peptides of 115 proteins were identified in fmp40{Delta} mitochondria, indicating on the presence of another, besides Fmp40, not yet identified AMPylase in yeast. We confirmed AMPylation of Atp1, Atp2, Atp3 and Atp16 subunits of mitochondrial ATP synthase by western blotting. Interestingly, we found AMPylation and phosphorylation of many residues, what indicates on the complex regulation of the ATP synthase activity. We confirmed the importance of one of such residues in Atp16, showing that its post-translational modification serves to regulate ATP synthase and OXPHOS coupling in both fermentative and respiratory growth conditions. This regulation serves to maintain the proper potential of the inner mitochondrial membrane, particularly under conditions of fermentative growth. This dataset represents the first library of AMPylated mitochondrial yeast proteins reported to date and supplements the AMPylome of human chronic lymphocytic leukemia cell line from human HYPE containing and HYPE lacking cells. The data represents a foundation for substrate specific investigations that can ultimately decipher the biological role of the AMPylation in the mitochondria.

molecular biology↗

bioRxiv2024

Efficient globin production during terminal erythropoiesis depends on the synergistic action of TENT5C poly(A) polymerase and LARP4/5

Red blood cell development is a unique process where reduced transcriptome and proteome complexity facilitates vast hemoglobin production. Here, we describe the cooperative role of cytoplasmic poly(A) polymerase TENT5C and the poly(A) tail-protecting LARP4/5 RNA-binding proteins in ensuring proper hemoglobin production. TENT5C catalytic mutant knock-in mice display microcytic hypochromic anemia resembling constitutive knockout. TENT5C counteracts gradual globin mRNA deadenylation during erythropoiesis. In the late stages, TENT5C dysfunction leads to globin poly(A) tail shortening and a drastic reduction of mRNA levels in reticulocytes. Proteomic experiments revealed transient but specific association of TENT5C with LARP4/5. Indeed, LARP4/5 depletion leads to downregulation and poly(A) tail shortening of globin mRNAs. Furthermore, lack of TENT5C catalytic activity is accompanied by compensatory upregulation of LARP4/5. Finally, the importance of precise regulation of globin poly(A) tails by deadenylation and re-adenylation is highlighted by the destabilization of TENT5C by CCR4-NOT deadenylase complex-associated E3 ubiquitin ligase CNOT4. O_FIG O_LINKSMALLFIG WIDTH=198 HEIGHT=200 SRC="FIGDIR/small/623596v1_ufig1.gif" ALT="Figure 1"> View larger version (59K): org.highwire.dtl.DTLVardef@82c736org.highwire.dtl.DTLVardef@1e4ea16org.highwire.dtl.DTLVardef@1c482b7org.highwire.dtl.DTLVardef@61e54a_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2024

Endothelial miR-34a deletion guards against aneurysm development despite endothelial dysfunction

ObjectivesOur previous study reported a reciprocal link between NRF2, a stress-responsive cytoprotective transcription factor, and aortic and endothelial cell (EC) ageing. We also found that NRF2 transcriptional knockout (tKO) mice are prone to abdominal aortic aneurysm (AAA) development. Given that miRNA-34a is a marker of ageing, in this study we explored its relationship with NRF2 and its role in vascular function and AAA formation. Approach and resultsThe experiments were performed in primary human aortic endothelial cells (HAECs) from young and aged donors and mice devoid of NRF2 transcriptional activity and endothelial miR-34a. The normolipidemic mice were challenged with angiotensin II (Ang II) to develop AAA. We show that premature NRF2-dependent aging of aortic endothelial cells (ECs) depends on miR-34a. Infusion of hypertensive Ang II in mice increases miR-34a in the aortic endothelial layer and serum, especially in mice which develop AAA. Mice deficient in endothelial miR-34a (miR-34a{Delta}EC) display severe EC dysfunction. Despite that, such mice are protected from AAA development, also on the NRF2 tKO background. Ang II infusion increases proliferation of intimal ECs in these mice. The protective effect of endothelial miR-34a deletion on AAA formation is reversed by rapamycin that suppresses EC proliferation. MTA2, but not SIRT1, is a direct target of miR-34a abrogating Ang II-induced EC proliferation. ConclusionsThese findings reveal that AAA development in NRF2 tKO mice relies on endothelial miR-34a overexpression. Deletion of endothelial miR-34a protects mice from AAA despite inducing endothelial cell dysfunction. The fine-tuning of EC proliferation may play a therapeutic role in the treatment of aneurysm.

pathology↗

bioRxiv2024

Effective recognition of double-stranded RNA does not require activation of cellular inflammation

Excess double-stranded RNA (dsRNA) is present in the cytoplasm of human cells, usually following viral infections. Recognition of dsRNAs activates innate immune pathways, leading to cellular inflammation and inhibition of cell growth. Here, we show that an effective dsRNA response may occur without the onset of inflammation. Interestingly, pro-inflammatory (RLR-dependent pathway) and cell growth inhibitory mechanisms (OAS/RNase L- and PKR-dependent pathways) can act independently. We found that the 5' ends of dsRNA direct the onset of cellular inflammation, whereas RNA duplex activates the OAS/RNase L and PKR pathways. Unexpectedly, three of the most common human RNA epitranscriptomic markers - i.e. N6-methyladenosine, 5-methylcytosine, and pseudouridine - did not affect the immunogenicity of dsRNA; however, the presence of N6-methyladenosine inhibited the OAS/RNase L pathway. Our observations demonstrate how precisely innate immunity is fine-tuned in cells to take appropriate countermeasures when a specific threat arises.

immunology↗

bioRxiv2022

DIS3L, cytoplasmic exosome catalytic subunit, is essential for development but not cell viability in mice.

Among numerous enzymes involved in RNA decay, processive exoribonucleases are the most prominent group responsible for the degradation of the entire RNA molecules. The role of mammalian cytoplasmic 3-5 exonuclease DIS3L at the organismal level remained unknown. Herein we established knock-in and knock-out mouse models to study DIS3L functions in mice. DIS3L is indeed a subunit of the cytoplasmic exosome complex, which disruption leads to severe embryo degeneration and death in mice soon after implantation. These changes could not be prevented by supplementing extraembryonic tissue with functional DIS3L through the construction of chimeric embryos. Preimplantation Dis3l-/- embryos were unaffected in their morphology and ability to produce functional embryonic stem cells showing that DIS3L is not essential for cell viability. There were also no major changes in the transcriptome level for both embryonic stem cells and blastocysts, as revealed by RNA sequencing experiments. Notably, however, DIS3L knock-out led to inhibition of the global protein synthesis. These results point to the essential role of DIS3L in mRNA quality control pathways crucial for proper protein synthesis during embryo development.

molecular biology↗

bioRxiv2022

2'-O -methylation of the second transcribed nucleotide within mRNA 5' cap impacts protein production level in a cell specific manner and contributes to RNA immune evasion

In higher eukaryotes, m7G-adjacent nucleotides undergo extensive modifications. Ribose of the first or first and second transcribed nucleotides can be subjected to 2-O-methylation to form cap1 or cap2, respectively. Additionally, when the first transcribed nucleotide is adenosine, it can not only undergo 2-O-methylation but can also be methylated at position N6 forming N6,2-O-dimethyladenosine (m6Am). Recent studies have shed some light on the functions of cap1, showing that cap1 in mammalian cells plays a crucial role in distinguishing between self and non-self RNA during viral infection. Here, we attempted to understand the impact of other cap methylations on RNA-related processes. Therefore, we synthesized tetranucleotide cap analogs and used them for efficient co-transcriptional RNA capping during in vitro transcription. Using this tool, we found that 2-O-methylation of the second transcribed nucleotide within the mRNA 5 cap influences protein production levels in a cell-specific manner. The presence of this modification can strongly hamper protein biosynthesis or do not influence protein production levels. Interestingly, 2-O-methylation of the second transcribed nucleotide as well as the presence of N6,2-O-dimethyladenosine as the first transcribed nucleotide serve as determinants that define transcripts as self and contribute to transcript escape from the host innate immune response. Additionally, cap methylation status does not influence transcript affinity towards translation initiation factor 4E or in vitro susceptibility to decapping by DCP2; however what we observe is resistance of RNA capped with cap2 to DXO-mediated decapping and degradation. Significance StatementMethylation of mRNA cap structure regulates protein biosynthesis in a cell-dependent manner. Among the three known m7G cap modifications, the 2-O-methylation is dominant. 2-O-methylation of the first transcribed nucleotide can boost protein production, whereas the same modification of the second transcribed nucleotide can strongly decrease translation. Interestingly, we show that in the JAWS II cell line, 2-O-methylation of mRNA cap had a prominent impact on the composition of the protein interactome associated with the RNA bearing mentioned modifications. Further analysis revealed that 2-O-methylation of the second transcribed nucleotide and N6-methylation of adenosine as the first transcribed nucleotide serve as determinants defining transcripts as self and contribute to transcript escape from the host innate immune response.

biochemistry↗

bioRxiv2021

Protein interaction network analysis reveals growth conditions-specific crosstalk between chromosomal DNA replication and other cellular processes in E. coli

E. coli and many other bacterial species can alter their cell cycle according to nutrient availability. Under optimal conditions bacteria grow and divide very fast but they slow down the cell cycle when conditions deteriorate. This adaptability is underlined by mechanisms coordinating cell growth with duplication of genetic material and cell division. Several mechanisms regulating DNA replication process in E. coli have been described with biochemical details so far. Nevertheless we still dont fully understand the source of remarkable precision that allows bacterial cells to coordinate their growth and chromosome replication. To shed light on regulation of E. coli DNA replication at systemic level, we used affinity purification coupled with mass spectrometry (AP-MS) to characterize protein-protein interactions (PPIs) formed by key E. coli replication proteins, under disparate bacterial growth conditions and phases. We present the resulting dynamic replication protein interaction network (PIN) and highlight links between DNA replication and several cellular processes, like outer membrane synthesis, RNA degradation and modification or starvation response. ImportanceDNA replication is a vital process, ensuring propagation of genetic material to progeny cells. Despite decades of studies we still dont fully understand how bacteria coordinate chromosomal DNA duplication with cell growth and cell division under optimal and stressful conditions. At molecular level, regulation of processes, including DNA replication, is often executed through direct protein-protein interactions (PPIs). In this work we present PPIs formed by the key E. coli replication proteins under three different bacterial growth conditions. We show novel PPIs with confirmed impact on chromosomal DNA replication. Our results provide also alternative explanations of genetic interactions uncovered before by others for E.coli replication machinery.

microbiology↗

bioRxiv2021

Heterotypic Assembly Mechanism Regulates CHIP E3 Ligase Activity

The E3 ubiquitin ligases CHIP/CHN-1 and UFD-2 team up to accelerate ubiquitin chain formation. However, it remained largely unclear how the high processivity of this E3 set is achieved. Here we studied the molecular mechanism and function of the CHN-1/UFD-2 complex in Caenorhabditis elegans. Our data show that UFD-2 binding promotes the cooperation between CHN-1 and ubiquitin-conjugating E2 enzymes by stabilizing the CHN-1 U-box dimer. The HSP-1 chaperone outcompetes UFD-2 for CHN-1 binding and promotes the auto-inhibited CHN-1 state by acting on the conserved position of the U-box domain. The interaction with UFD-2 enables CHN-1 to efficiently ubiquitinate S-Adenosylhomocysteinase (AHCY-1), an enzyme crucial for lipid metabolism. Our results define the molecular mechanism underlying the synergistic cooperation of CHN-1 and UFD-2 in substrate ubiquitylation. HIGHLIGHTSO_LIE3 ligase UFD-2 stimulates ubiquitylation activity of CHIP/CHN-1 C_LIO_LIUFD-2 binding promotes dimerization of CHIP/CHN-1 U-box domains and utilization of E2 enzymes C_LIO_LIHSP70/HSP-1 by latching the U-box and TPR domains stabilizes the autoinhibitory state of CHIP/CHN-1, limiting interactions with E2s and UFD-2 C_LIO_LIAssembly with UFD-2 enables CHIP/CHN-1 to regulate lipid metabolism by ubiquitylation of S-Adenosylhomocysteinase C_LI

molecular biology↗

bioRxiv2020

Cytoplasmic polyadenylation by TENT5A is required for proper bone formation

Osteoblasts orchestrate bone formation by secreting dense, highly cross-linked type I collagen and other proteins involved in osteogenesis. Mutations in Col11, Col12, or collagen biogenesis factors lead to the human genetic disease, osteogenesis imperfecta (OI). Herein, we show that the TENT5A gene, whose mutation is responsible for poorly characterized type XVIII OI, encodes an active cytoplasmic poly(A) polymerase regulating osteogenesis. TENT5A is induced during osteoblast differentiation and TENT5A KO osteoblasts are defective in mineralization. The TENT5A KO mouse recapitulates OI disease symptoms such as bone fragility and hypomineralization. Direct RNA sequencing revealed that TENT5A polyadenylates and increases expression of Col11 and Col12 RNAs, as well as those of other genes mutated in OI, resulting in lower production and improper folding of collagen chains. Thus, we have identified the specific pathomechanism of XVIII OI and report for the first time a biologically relevant post-transcriptional regulator of collagen production. We further postulate that TENT5A, possibly together with its paralogue TENT5C, is responsible for the wave of cytoplasmic polyadenylation of mRNAs encoding secreted proteins occurring during bone mineralization.

genetics↗

bioRxiv2019

Mitochondria biogenesis in the synapse is supported by local translation

Synapses are the regions of the neuron that enable the transmission and propagation of action potentials on the cost of high energy consumption and elevated demand for mitochondrial ATP production. The rapid changes in local energetic requirements at dendritic spines imply the role of mitochondria in the maintenance of their homeostasis. Using global proteomic analysis supported with complementary experimental approaches, we show that an important pool of mitochondrial proteins is locally produced at the synapse indicating that mitochondrial biogenesis takes place locally to maintain the pool of functional mitochondria in axons and dendrites. Furthermore, we show that stimulation of synaptoneurosomes induces the local synthesis of mitochondrial proteins that are transported to the mitochondria and incorporated into the protein supercomplexes of the respiratory chain.\n\nSynopsis\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=187 SRC=\"FIGDIR/small/789164v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (47K):\norg.highwire.dtl.DTLVardef@1813d6forg.highwire.dtl.DTLVardef@1e85cd3org.highwire.dtl.DTLVardef@2656f7org.highwire.dtl.DTLVardef@1177d7d_HPS_FORMAT_FIGEXP M_FIG Mitochondria biogenesis in the synapse is supported by local translation\n\nC_FIG O_LIMitochondrial proteins represent a large pool of proteins synthesized locally at the synapse\nC_LIO_LINewly synthesized mitochondrial proteins are imported into the mitochondria and incorporated into the respiratory chain complexes\nC_LIO_LIUncoupling of mitochondria and blocking mitochondrial import inhibits incorporation of de novo synthesized proteins into the mitochondrial protein complexes\nC_LI

neuroscience↗

bioRxiv2018

Tunneling nanotubes contribute to the stroma-mediated imatinib resistance of leukemic cells

Intercellular communication within the bone marrow niche significantly influences leukemogenesis and the sensitivity of leukemic cells to therapy. Tunneling nanotubes (TNTs) are a novel mode of intercellular cross-talk. They are long, thin membranous protrusions that enable the direct transfer of various cargo between cells. Here we show that TNTs are formed between leukemic and bone marrow stromal cells. Fluorescence confocal microscopy with 3D reconstructions, correlative light-electron microscopy and electron tomography provided evidence that TNTs transfer cellular vesicles between cells. The quantitative analysis demonstrated that the stromal cells stimulate TNT-mediated vesicle transfer towards leukemic cells. Transfer of vesicular cargo from stromal cells correlated with increased resistance to anti-leukemic treatment. Moreover, specific sets of proteins with a potential role in survival and the drug response were transferred within these vesicles. Altogether, we found that TNTs are involved in the leukemia-stroma cross-talk and the stroma-mediated cytoprotection of leukemic cells. Our findings implicate TNT connections as a possible target for therapeutic interventions within the leukemia microenvironment to attenuate stroma-conferred protection.

cancer biology↗

bioRxiv2018

Inhibition of proteasomal degradation rescues a pathogenic variant of mitochondrial Respiratory chain assembly 1 factor

Nuclear and mitochondrial genome mutations lead to various mitochondrial diseases, many of which affect the mitochondrial respiratory chain. The proteome of the intermembrane space (IMS) of mitochondria consists of several important assembly factors that participate in the biogenesis of mitochondrial respiratory chain complexes. The present study comprehensively analyzed a recently identified IMS protein, RESpiratory chain Assembly 1 (RESA1) factor, or cytochrome c oxidase assembly factor 7 (COA7) that is associated with a rare form of mitochondrial leukoencephalopathy and complex IV deficiency. We found that RESA1 requires the mitochondrial IMS import and assembly (MIA) pathway for efficient accumulation in the IMS. We also found that pathogenic mutant versions of RESA1 are imported slower than the wild type protein, and mislocalized mutant proteins are degraded in the cytosol by proteasome machinery. Interestingly, proteasome inhibition rescued both the mitochondrial localization of mutant RESA1 and complex IV activity in patient-derived fibroblasts. We propose that proteasome inhibition is a novel therapeutic approach for a broad range of mitochondrial pathologies that are associated with the excessive degradation of mitochondrial proteins that is caused by genetic mutations or biogenesis defects.

biochemistry↗

bioRxiv2017

Versatile approach for functional analysis of human proteins and efficient stable cell line generation using FLP-mediated recombination system

Deciphering a function of a given protein requires investigating various biological aspects. Usually, the protein of interest is expressed with a fusion tag that aids or allows subsequent analyses. Additionally, downregulation or inactivation of the studied gene enables functional studies. Development of the CRISPR/Cas9 methodology opened many possibilities but in many cases it is restricted to non-essential genes. It may also be time-consuming if a homozygote is needed. Recombinase-dependent gene integration methods, like the Flp-In system, are very good alternative. The system is widely used in different research areas, which calls for the existence of compatible vectors and efficient protocols that ensure straightforward DNA cloning and creation of stable cell lines. We have created and validated a robust series of 52 vectors for streamlined generation of stable mammalian cell lines using the FLP recombinase-based methodology. Using the sequence-independent DNA cloning method all constructs for a given coding-sequence can be made with just three universal PCR primers. The collection allows tetracycline-inducible expression of proteins with various tags suitable for protein localization, FRET, bimolecular fluorescence complementation (BiFC), protein dynamics studies (FRAP), co-immunoprecipitation, the RNA tethering assay and cell sorting. Some of the vectors contain a bidirectional promoter for concomitant expression of miRNA and mRNA, so that a gene can be silenced and its product replaced by a mutated miRNA-insensitive version. We demonstrate the efficacy of our vectors by creating stable cell lines with various tagged proteins (numatrin, fibrillarin, coilin, centrin, THOC5, PCNA). We have analysed transgene expression over time to provide a guideline for future experiments and compared the utility of commonly used inducers of tetracycline-responsive promoters. We determined the protein interaction network of the exoribonuclease XRN2 and examined the role of the protein in transcription termination by RNAseq analysis of cells devoid of its ribonucleolytic activity. In total we created more than 500 DNA constructs which proves high efficiency of our strategy.

molecular biology↗