Ribosomal protein genes (RPGs) in Saccharomyces cerevisiae are a remarkable regulatory group that may serve as a model for understanding genetic redundancy in evolutionary adaptations. Most RPGs exist as pairs of highly conserved functional paralogs with divergent untranslated regions and introns. We examined the roles of introns in strains with various combinations of intron and gene deletions in RPL22, RPL2, RPL16, RPL37, RPL17, RPS0, and RPS18 paralog pairs. We found that introns inhibited the expression of their genes in the RPL22 pair, with the RPL22B intron conferring a much stronger effect. While the WT RPL22A/RPL22B mRNA ratio was 93/7, the rpl22aΔi/RPL22B and RPL22A/rpl22bΔi ratios were >99/<1 and 60/40, respectively. The intron in RPL2A stimulated the expression of its own gene, but the removal of the other introns had little effect on expression of the corresponding gene pair. Rpl22 protein abundances corresponded to changes in mRNAs. Using splicing reporters containing endogenous intron sequences, we demonstrated that these effects were due to the inhibition of splicing by Rpl22 proteins but not by their RNA-binding mutant versions. Indeed, only WT Rpl22A/Rpl22B proteins (but not the mutants) interacted in a yeast three-hybrid system with an RPL22B intronic region between bp 165 and 236. Transcriptome analysis showed that both the total level of Rpl22 and the A/B ratio were important for maintaining the WT phenotype. The data presented here support the contention that the Rpl22B protein has a paralog-specific role. The RPL22 singleton of Kluyveromyces lactis, which did not undergo whole genome duplication, also responded to Rpl22-mediated inhibition in K. lactis cells. Vice versa, the overproduction of the K. lactis protein reduced the expression of RPL22A/B in S. cerevisiae. The extraribosomal function of of the K. lactis Rpl22 suggests that the loop regulating RPL22 paralogs of S. cerevisiae evolved from autoregulation.
Splicing in S. cerevisiae has been shown to proceed cotranscriptionally, but the nature of the coupling remains a subject of debate. Here, we examine the effect of nineteen complex-related splicing factor Prp45 (a homolog of SNW1/SKIP) on cotranscriptional splicing. RNA-sequencing and RT-qPCR showed elevated pre-mRNA levels but only limited reduction of spliced mRNAs in cells expressing C-terminally truncated Prp45, Prp45(1-169). Assays with a series of reporters containing the AMA1 intron with regulatable splicing confirmed decreased splicing efficiency and showed the leakage of unspliced RNAs in prp45(1-169) cells. We also measured pre-mRNA accumulation of the meiotic MER2 gene, which depends on the expression of Mer1 factor for splicing. prp45(1-169) cells accumulated approximately threefold higher levels of MER2 pre-mRNA than WT cells only when splicing was induced. To monitor cotranscriptional splicing, we determined the presence of early spliceosome assembly factors and snRNP complexes along the ECM33 and ACT1 genes. We found that prp45(1-169) hampered the cotranscriptional recruitment of U2 and, to a larger extent, U5 and NTC, while the U1 profile was unaffected. The recruitment of Prp45(1-169) was impaired similarly to U5 snRNP and NTC. Our results imply that Prp45 is required for timely formation of complex A, prior to stable physical association of U5/NTC with the emerging pre-mRNA substrate. We suggest that Prp45 facilitates conformational rearrangements and/or contacts that couple U1 snRNP-recognition to downstream assembly events.
- MeSH
- introny MeSH
- malý jaderný ribonukleoprotein U1 metabolismus MeSH
- malý jaderný ribonukleoprotein U2 metabolismus MeSH
- Saccharomyces cerevisiae - proteiny genetika metabolismus MeSH
- Saccharomyces cerevisiae genetika metabolismus MeSH
- sestřih RNA * MeSH
- spliceozomy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Pre-mRNA splicing represents an important regulatory layer of eukaryotic gene expression. In the simple budding yeast Saccharomyces cerevisiae, about one-third of all mRNA molecules undergo splicing, and splicing efficiency is tightly regulated, for example, during meiotic differentiation. S. cerevisiae features a streamlined, evolutionarily highly conserved splicing machinery and serves as a favourite model for studies of various aspects of splicing. RNA-seq represents a robust, versatile, and affordable technique for transcriptome interrogation, which can also be used to study splicing efficiency. However, convenient bioinformatics tools for the analysis of splicing efficiency from yeast RNA-seq data are lacking. We present a complete workflow for the calculation of genome-wide splicing efficiency in S. cerevisiae using strand-specific RNA-seq data. Our pipeline takes sequencing reads in the FASTQ format and provides splicing efficiency values for the 5' and 3' splice junctions of each intron. The pipeline is based on up-to-date open-source software tools and requires very limited input from the user. We provide all relevant scripts in a ready-to-use form. We demonstrate the functionality of the workflow using RNA-seq datasets from three spliceosome mutants. The workflow should prove useful for studies of yeast splicing mutants or of regulated splicing, for example, under specific growth conditions.
For every eukaryotic cell to grow and divide, intricately coordinated action of numerous proteins is required to ensure proper cell-cycle progression. The fission yeast Schizosaccharomyces pombe has been instrumental in elucidating the fundamental principles of cell-cycle control. Mutations in S. pombe 'cut' (cell untimely torn) genes cause failed coordination between cell and nuclear division, resulting in catastrophic mitosis. Deletion of cbf11, a fission yeast CSL transcription factor gene, triggers a 'cut' phenotype, but the precise role of Cbf11 in promoting mitotic fidelity is not known. We report that Cbf11 directly activates the transcription of the acetyl-coenzyme A carboxylase gene cut6, and the biotin uptake/biosynthesis genes vht1 and bio2, with the former 2 implicated in mitotic fidelity. Cbf11 binds to a canonical, metazoan-like CSL response element (GTGGGAA) in the cut6 promoter. Expression of Cbf11 target genes shows apparent oscillations during the cell cycle using temperature-sensitive cdc25-22 and cdc10-M17 block-release experiments, but not with other synchronization methods. The penetrance of catastrophic mitosis in cbf11 and cut6 mutants is nutrient-dependent. We also show that drastic decrease in biotin availability arrests cell proliferation but does not cause mitotic defects. Taken together, our results raise the possibility that CSL proteins play conserved roles in regulating cell-cycle progression, and they could guide experiments into mitotic CSL functions in mammals.
- MeSH
- biotin metabolismus MeSH
- DNA fungální metabolismus MeSH
- genetická epistáze MeSH
- genetická transkripce MeSH
- geny hub * MeSH
- mitóza genetika MeSH
- mutace genetika MeSH
- promotorové oblasti (genetika) MeSH
- regulace genové exprese u hub * MeSH
- Schizosaccharomyces pombe - proteiny genetika metabolismus MeSH
- Schizosaccharomyces cytologie genetika MeSH
- vazba proteinů genetika MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Cbf11 and Cbf12, the fission yeast CSL transcription factors, have been implicated in the regulation of cell-cycle progression, but no specific roles have been described and their target genes have been only partially mapped. METHODOLOGY/PRINCIPAL FINDINGS: Using a combination of transcriptome profiling under various conditions and genome-wide analysis of CSL-DNA interactions, we identify genes regulated directly and indirectly by CSL proteins in fission yeast. We show that the expression of stress-response genes and genes that are expressed periodically during the cell cycle is deregulated upon genetic manipulation of cbf11 and/or cbf12. Accordingly, the coordination of mitosis and cytokinesis is perturbed in cells with genetically manipulated CSL protein levels, together with other specific defects in cell-cycle progression. Cbf11 activity is nutrient-dependent and Δcbf11-associated defects are mitigated by inactivation of the protein kinase A (Pka1) and stress-activated MAP kinase (Sty1p38) pathways. Furthermore, Cbf11 directly regulates a set of lipid metabolism genes and Δcbf11 cells feature a stark decrease in the number of storage lipid droplets. CONCLUSIONS/SIGNIFICANCE: Our results provide a framework for a more detailed understanding of the role of CSL proteins in the regulation of cell-cycle progression in fission yeast.
- MeSH
- cytokineze MeSH
- fyziologický stres MeSH
- mitogenem aktivované proteinkinasy genetika MeSH
- mitóza MeSH
- proteinkinasy závislé na cyklickém AMP genetika MeSH
- regulace genové exprese u hub MeSH
- Schizosaccharomyces pombe - proteiny genetika metabolismus MeSH
- Schizosaccharomyces genetika metabolismus MeSH
- stanovení celkové genové exprese metody MeSH
- transkripční faktory genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Transcription factors of the CSL (CBF1/RBP-Jk/Suppressor of Hairless/LAG-1) family are key regulators of metazoan development and function as the effector components of the Notch receptor signalling pathway implicated in various cell fate decisions. CSL proteins recognize specifically the GTG[G/A]AA sequence motif and several mutants compromised in their ability to bind DNA have been reported. In our previous studies we have identified a number of novel putative CSL family members in fungi, organisms lacking the Notch pathway. It is not clear whether these represent genuine CSL family members. METHODOLOGY/PRINCIPAL FINDINGS: Using a combination of in vitro and in vivo approaches we characterized the DNA binding properties of Cbf11 and Cbf12, the antagonistic CSL paralogs from the fission yeast, important for the proper coordination of cell cycle events and the regulation of cell adhesion. We have shown that a mutation of a conserved arginine residue abolishes DNA binding in both CSL paralogs, similar to the situation in mouse. We have also demonstrated the ability of Cbf11 and Cbf12 to activate gene expression in an autologous fission yeast reporter system. CONCLUSIONS/SIGNIFICANCE: Our results indicate that the fission yeast CSL proteins are indeed genuine family members capable of functioning as transcription factors, and provide support for the ancient evolutionary origin of this important protein family.
- MeSH
- aktivní transport - buněčné jádro MeSH
- buněčný cyklus MeSH
- DNA fungální metabolismus MeSH
- konzervovaná sekvence MeSH
- mutace MeSH
- reportérové geny genetika MeSH
- responzivní elementy genetika MeSH
- Schizosaccharomyces pombe - proteiny chemie genetika metabolismus MeSH
- Schizosaccharomyces cytologie genetika metabolismus MeSH
- sekvence nukleotidů MeSH
- sekvenční homologie aminokyselin MeSH
- transkripční faktory chemie genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Higher order RNA structures can mask splicing signals, loop out exons, or constitute riboswitches all of which contributes to the complexity of splicing regulation. We identified a G to A substitution between branch point (BP) and 3' splice site (3'ss) of Saccharomyces cerevisiae COF1 intron, which dramatically impaired its splicing. RNA structure prediction and in-line probing showed that this mutation disrupted a stem in the BP-3'ss region. Analyses of various COF1 intron modifications revealed that the secondary structure brought about the reduction of BP to 3'ss distance and masked potential 3'ss. We demonstrated the same structural requisite for the splicing of UBC13 intron. Moreover, RNAfold predicted stable structures for almost all distant BP introns in S. cerevisiae and for selected examples in several other Saccharomycotina species. The employment of intramolecular structure to localize 3'ss for the second splicing step suggests the existence of pre-mRNA structure-based mechanism of 3'ss recognition.
- MeSH
- Ascomycota genetika MeSH
- fungální RNA chemie MeSH
- introny MeSH
- kofilin 1 genetika MeSH
- konformace nukleové kyseliny MeSH
- místa sestřihu RNA MeSH
- molekulární sekvence - údaje MeSH
- Saccharomyces cerevisiae - proteiny genetika MeSH
- Saccharomyces cerevisiae genetika MeSH
- sekvence nukleotidů MeSH
- sestřih RNA MeSH
- teplota MeSH
- ubikvitin konjugující enzymy genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Pharmacological inhibition of protein kinases that are responsible for the phosphorylation of the carboxy-terminal domain (CTD) of RNA Pol II during transcription by 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB) leads to severe inhibition of mRNA synthesis and activates p53. Transcription of the p53 effectors that are induced under these conditions, such as p21 or PUMA, must bypass the requirement for CTD phosphorylation by the positive elongation factor P-TEFb. Here, we have downregulated SNW1/SKIP, a splicing factor and a transcriptional co-regulator, which was found to interact with P-TEFb and synergistically affect Tat-dependent transcription elongation of HIV 1. Using the colon cancer derived cell line HCT116, we have found that both doxorubicin- and DRB-induced expression of p21 or PUMA is insensitive to SNW1 downregulation by siRNA. This suggests that transcription of stress response genes, unlike, e.g., the SNW1-sensitive mitosis-specific genes, can proceed uncoupled from regulators that normally function under physiological conditions.
- MeSH
- buněčné jádro metabolismus MeSH
- down regulace genetika MeSH
- fyziologický stres genetika MeSH
- HCT116 buňky MeSH
- HeLa buňky MeSH
- koaktivátory jaderných receptorů genetika metabolismus MeSH
- lidé MeSH
- lidské chromozomy metabolismus MeSH
- mitóza MeSH
- nádorový supresorový protein p53 metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The newly established breast cancer cell line G3S1, derived from EM-G3 breast cancer progenitors, was analyzed for functional changes related to neoplastic progression manifested by elevated invasiveness and enhanced capability to degrade gelatin. Degradation of gelatin and invasiveness of G3S1 cells was found to be dependent on the activity of matrix proteinases and actin cytoskeletal dynamics. Therefore, the expression and activity of these proteases was compared in G3S1 and EM-G3 cells. Despite enhanced capability of G3S1 cells to degrade gelatin, these cells exhibited lower levels of secreted extracellular matrix degrading proteases than parental EM-G3 cells. However, the expression of membrane-bound MT1-MMP was strongly elevated in G3S1 cells. While the degradation of gelatin was associated with invadopodia-like structures in both EM-G3 and G3S1 cells, the cytoskeletal remodeling dynamics was greatly elevated in G3S1 cells, suggesting that upregulation of MT1-MMP, together with elevation of cytoskeletal remodeling dynamics can effectively cause elevated invasiveness and enhanced matrix degrading capability in G3S1 cells.
- MeSH
- aktiny metabolismus MeSH
- aprotinin farmakologie MeSH
- cytoskelet účinky léků enzymologie patologie MeSH
- dipeptidy farmakologie MeSH
- inhibitory matrixových metaloproteinas MeSH
- inhibitory proteas farmakologie MeSH
- invazivní růst nádoru MeSH
- leucin analogy a deriváty farmakologie MeSH
- lidé MeSH
- matrixová metaloproteinasa 14 metabolismus MeSH
- metaloproteinasy secernované do matrix metabolismus MeSH
- mořské toxiny farmakologie MeSH
- nádorové buněčné linie MeSH
- nádorové kmenové buňky enzymologie patologie MeSH
- nádory prsu enzymologie patologie MeSH
- pohyb buněk účinky léků MeSH
- progrese nemoci MeSH
- pseudopodia enzymologie MeSH
- upregulace MeSH
- želatina metabolismus MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Invadopodia and podosomes have been intensively studied because of their involvement in the degradation of extracellular matrix. As both structures have been studied mostly on thin matrices, their commonly reported shapes and characteristics may differ from those in vivo. To assess the morphology of invadopodia in a complex 3D environment, we observed invadopodial formation in cells grown on a dense matrix based on cell-free dermis. We have found that invadopodia differ in morphology when cells grown on the dermis-based matrix and thin substrates are compared. The cells grown on the dermis-based matrix display invadopodia which are formed by a thick protruding base rich in F-actin, phospho-paxillin, phospho-cortactin and phosphotyrosine signal, from which numerous thin filaments protrude into the matrix. The protruding filaments are composed of an F-actin core and are free of phospho-paxillin and phospho-cortactin but capped by phosphotyrosine signal. Furthermore, we found that a matrix-degrading activity is localized to the base of invadopodia and not along the matrix-penetrating protrusions. Our description of invadopodial structures on a dermis-based matrix should greatly aid the development of new criteria for the identification of invadopodia in vivo, and opens up the possibility of studying the invadopodia-related signaling in a more physiological environment.
- MeSH
- aktiny metabolismus MeSH
- buněčné kultury MeSH
- buněčné výběžky metabolismus ultrastruktura MeSH
- cytoskelet metabolismus MeSH
- elektronová mikroskopie MeSH
- experimentální sarkom metabolismus ultrastruktura MeSH
- extracelulární matrix metabolismus fyziologie ultrastruktura MeSH
- fluorescenční protilátková technika MeSH
- kortaktin metabolismus MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- prasata MeSH
- signální transdukce MeSH
- zobrazování trojrozměrné MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
