SF3B1 Interactions with Chromatin Are Dynamic and Regulated in a Cell Cycle-Dependent Manner

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1480-1480
Author(s):  
Tushar Murthy ◽  
Theresa Bluemn ◽  
Manoj M. Pillai ◽  
Alex C Minella
Keyword(s):  
Cell Cycle ◽  
Rna Splicing ◽  
Cell Cycle Progression ◽  
Conflicts Of Interest ◽  
S Phase ◽  
Chromatin Interaction ◽  
Dependent Manner ◽  
Direct Role ◽  
Cycle Progression ◽  
Cycle Dependent

Abstract Splicing factor 3B1 (SF3B1) is a member of the U2 snRNP complex that is a key regulator of RNA splicing. RNA splicing begins with the recognition of splice sites (ss) at the 5' and 3' ends of introns and ends with the removal of introns and joining of exons flanking them. SF3B1 plays an important role in this process by facilitating the recognition of the 3'ss. SF3B1 is frequently mutated in numerous cancers as well as the myelodysplastic syndromes (MDS). Mutations within the HEAT domain of the protein potentially contribute to disease pathogenesis. In addition to influencing splicing by binding to pre-mRNA, SF3B1 has been shown to affect splicing of exons by associating with them directly on chromatin via histone/nucleosome interactions. However, it is not understood if or how SF3B1 association with chromatin is regulated. Given that N-terminal serine and threonine residues on SF3B1 are known substrates of cyclin E-Cdk2, which phosphorylates histone subunits and other chromatin associated proteins, we hypothesized that CDK2 activity regulates SF3B1-nucleosome interactions. Although SF3B1 is phosphorylated during splicing catalysis, the function of this phosphorylation has remained unknown. We have now discovered, using nucleosome preparations and histone subunit co-immunoprecipitation assays in synchronized cells, that endogenous SF3B1 interacts with nucleosomes in a highly cell-cycle dependent manner, while total cellular abundance of SF3B1 remains invariant during cell cycle progression. In human and mouse cells, including hematopoietic cell lines, SF3B1 is excluded from chromatin during both G0 (quiescence) and G2/M phases of cell cycle. Notably, SF3B1 is enriched within chromatin maximally during S-phase. Unexpectedly, we found that the inhibition of Cdc2 (Cdk1) during G2/M enforces the SF3B1-chromatin interaction, pointing to a direct role for Cdc2 in restraining this interaction during mitosis. Further, SF3B1 loading onto chromatin during early cell cycle progression from G0 to S-phase is inhibited by Cdk2 inhibition. Thus, Cdk2 and Cdc2 appear to have antagonistic roles in controlling SF3B1-chromatin interactions during the cell cycle. Our findings suggest that Cdk activity may regulate the recruitment of the spliceosome machinery in order to coordinate splicing of particular transcripts with cell cycle progression. Current studies are focusing on how disease-associated mutations in the HEAT domain of SF3B1 affect the dynamics of its cell cycle-dependent interaction with nucleosomes and corresponding alterations to splicing outcomes. Disclosures No relevant conflicts of interest to declare.

scholarly journals Cell cycle progression and transmitotic apoptosis resistance promote escape from extrinsic apoptosis

2021 ◽  
Author(s):  
Nadine Pollak ◽  
Aline Lindner ◽  
Dirke Imig ◽  
Karsten Kuritz ◽  
Jacques S. Fritze ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Receptor Activation ◽  
S Phase ◽  
Apoptosis Resistance ◽  
Cycle Progression ◽  
Extrinsic Apoptosis ◽  
Primed State ◽  
Pass Through ◽  
Cycle Dependent

Extrinsic apoptosis relies on TNF-family receptor activation by immune cells or receptor-activating biologics. Here, we monitored cell cycle progression at minutes resolution to relate apoptosis kinetics and cell-to-cell heterogeneities in death decisions to cell cycle phases. Interestingly, we found that cells in S phase delay TRAIL receptor-induced death in favour for mitosis, thereby passing on an apoptosis-primed state to their offspring. This translates into two distinct fates, apoptosis execution post mitosis or cell survival from inefficient apoptosis. Transmitotic resistance is linked to Mcl-1 upregulation and increased accumulation at mitochondria from mid S phase onwards, which allows cells to pass through mitosis with activated caspase-8, and with cells escaping apoptosis after mitosis sustaining sublethal DNA damage. Antagonizing Mcl-1 suppresses cell cycle-dependent delays in apoptosis, prevents apoptosis-resistant progression through mitosis and averts unwanted survival from apoptosis induction. Cell cycle progression therefore modulates signal transduction during extrinsic apoptosis, with Mcl-1 governing decision making between death, proliferation and survival. Cell cycle progression thus is a crucial process from which cell-to-cell heterogeneities in fates and treatment outcomes emerge in isogenic cell populations during extrinsic apoptosis.

Differential induction of ‘metabolic genes’ after mitogen stimulation and during normal cell cycle progression

1994 ◽  
Vol 107 (1) ◽  
pp. 241-252 ◽  
Author(s):  
C. Burger ◽  
M. Wick ◽  
S. Brusselbach ◽  
R. Muller
Keyword(s):  
Cell Cycle ◽  
Normal Cell ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Cycle Progression ◽  
Genes Encoding ◽  
A Cell ◽  
Induced Genes ◽  
Cycle Dependent ◽  
Normal Cell Cycle

Mitogenic stimulation of quiescent cells not only triggers the cell division cycle but also induces an increase in cell volume, associated with an activation of cellular metabolism. It is therefore likely that genes encoding enzymes and other proteins involved in energy metabolism and biosynthetic pathways represent a major class of mitogen-induced genes. In the present study, we investigated in the non-established human fibroblast line WI-38 the induction by mitogens of 17 genes whose products play a role in different metabolic processes. We show that these genes fall into 4 different categories, i.e. non-induced genes, immediate early (IE) primary genes, delayed early (DE) secondary genes and late genes reaching peak levels in S-phase. In addition, we have analysed the regulation of these genes during normal cell cycle progression, using HL-60 cells separated by counterflow elutriation. A clear cell cycle regulation was seen with those genes that are induced in S-phase, i.e. thymidine kinase, thymidylate synthase and dihydrofolate reductase. In addition, two DE genes showed a cell cycle dependent expression. Ornithine decarboxylase mRNA increased around mid-G1, reaching maximum levels in S/G2, while hexokinase mRNA expression was highest in early G1. In contrast, the expression of other DE and IE genes did not fluctuate during the cell cycle, a result that was confirmed with elutriated WI-38 and serum-stimulated HL-60 cells. These observations suggest that G0-->S and G1-->S transition are distinct processes, exhibiting characteristic programmes of gene regulation, and merging around S-phase entry.

scholarly journals Morphogenesis checkpoint kinase Swe1 is the executor of lipolysis-dependent cell-cycle progression

2015 ◽  
Vol 112 (10) ◽  
pp. E1077-E1085 ◽  
Author(s):  
Neha Chauhan ◽  
Myriam Visram ◽  
Alvaro Cristobal-Sarramian ◽  
Florian Sarkleti ◽  
Sepp D. Kohlwein
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Sphingolipid Metabolism ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Checkpoint Kinase ◽  
Cell Cycle Delay ◽  
A Cell ◽  
Morphogenesis Checkpoint ◽  
Cycle Dependent

Cell growth and division requires the precise duplication of cellular DNA content but also of membranes and organelles. Knowledge about the cell-cycle–dependent regulation of membrane and storage lipid homeostasis is only rudimentary. Previous work from our laboratory has shown that the breakdown of triacylglycerols (TGs) is regulated in a cell-cycle–dependent manner, by activation of the Tgl4 lipase by the major cyclin-dependent kinase Cdc28. The lipases Tgl3 and Tgl4 are required for efficient cell-cycle progression during the G1/S (Gap1/replication phase) transition, at the onset of bud formation, and their absence leads to a cell-cycle delay. We now show that defective lipolysis activates the Swe1 morphogenesis checkpoint kinase that halts cell-cycle progression by phosphorylation of Cdc28 at tyrosine residue 19. Saturated long-chain fatty acids and phytosphingosine supplementation rescue the cell-cycle delay in the Tgl3/Tgl4 lipase-deficient strain, suggesting that Swe1 activity responds to imbalanced sphingolipid metabolism, in the absence of TG degradation. We propose a model by which TG-derived sphingolipids are required to activate the protein phosphatase 2A (PP2ACdc55) to attenuate Swe1 phosphorylation and its inhibitory effect on Cdc28 at the G1/S transition of the cell cycle.

scholarly journals Cell-to-cell heterogeneities during extrinsic apoptosis arise from cell cycle progression and transmitotic apoptosis resistance

2021 ◽  
Author(s):  
Nadine Pollak ◽  
Aline Lindner ◽  
Dirke Imig ◽  
Karsten Kuritz ◽  
Jacques S. Fritze ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Receptor Activation ◽  
S Phase ◽  
Apoptosis Induction ◽  
Apoptosis Resistance ◽  
Cycle Progression ◽  
Extrinsic Apoptosis ◽  
Pass Through ◽  
Cycle Dependent

AbstractExtrinsic apoptosis relies on TNF-family receptor activation by immune cells or receptor-activating biologics. Here, we monitored cell cycle progression at minutes resolution to relate apoptosis kinetics and cell-to-cell heterogeneities in death decisions to cell cycle phases. Interestingly, we found that cells in S phase delay TRAIL receptor-induced death in favour for mitosis, thereby passing on an apoptosis-primed state to their offspring. This translates into two distinct fates, apoptosis execution post mitosis or cell survival from inefficient apoptosis. Transmitotic resistance is linked to Mcl-1 upregulation from mid S phase onwards, which allows cells to pass through mitosis with activated caspase-8, and with cells escaping apoptosis after mitosis sustaining sublethal DNA damage. Antagonizing Mcl-1 by BH3-mimetics suppresses cell cycle-dependent delays in apoptosis, prevents apoptosis-resistant progression through mitosis and averts unwanted survival from apoptosis induction. Cell cycle progression therefore modulates signal transduction during extrinsic apoptosis, with Mcl-1 governing decision making between death, proliferation and survival from inefficient apoptosis induction. Cell cycle progression thus is a crucial process from which cell-to-cell heterogeneities in fates and treatment outcomes emerge in isogenic cell populations during extrinsic apoptosis signalling.

Systems Biology Analysis of Human Primary T Cells Identifies SAP145 as Rate Limiting for the G1→S Phase Transition.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3350-3350
Author(s):  
Stephen J. Orr ◽  
Rong Wang ◽  
Nicholas C. Lea ◽  
Constantinos Chronis ◽  
Arun K. Ramani ◽  
...  
Keyword(s):  
Cell Cycle ◽  
T Cells ◽  
Systems Biology ◽  
Rna Splicing ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Phase Cell ◽  
Cycle Progression ◽  
Human T Cells ◽  
Rate Limiting

Abstract We identified a G0→G1 commitment point in primary human T cells that controls entry into the cell cycle from quiescence. We demonstrated proof of principle that cellular pathways regulating cell cycle progression and effector functions that normally coincide during CD3/CD28 stimulation can be uncoupled experimentally. We have now used systems biology approaches to identify nuclear protein networks in primary human T cells that are regulated during the transition from quiescence into the cell cycle (G0→G1→S-phase). First we sequenced proteins that became bound to chromatin & nuclear matrix in G1 but were not bound in G0 and vice versa by mass spectrometry. Bioinformatic analysis identified 76 proteins specifically bound in G0 not G1 and 254 bound in G1 not G0. 179 of the 254 proteins bound in G1 not G0 (i.e. dynamic protein changes) were mapped to the 55,000 human protein interaction dataset. These are involved in numerous cellular functions, including epigenetics, transcription, RNA splicing & transport, and others. Cell cycle regulated chromatin/matrix binding of a subset was verified by western blotting (2/2 bound in G0 not G1 and 22/23 bound in G1 not G0). One of the proteins induced and bound in G1 was SAP145 (SF3B2). This is a component of the ubiquitous SF3b RNA splicing complex, involved in both major (U2-type) and minor (U12-type) spliceosomes. Since SAP145 is induced during G1 we investigated whether there was a role for SAP145 in regulating cell cycle progression. T cells depleted of SAP145 by siRNA enter G1 from G0 but progress poorly through S phase and die, probably by apoptosis. The same occurs if another component of the SF3B complex, SAP49 (SF3B4) is depleted with siRNA, indicating that the effect is due to depleting the complex rather than the individual SF3B protein. Proteins that are induced during G1 by CD3/CD28 stimulation e.g. cyclin D3, Cdc6 and cdc2 are produced normally when SAP145 is depleted, suggesting that their pre-mRNAs are spliced normally. In contrast, the expression of p107 and cyclin A2 are reduced markedly when SAP145 is depleted. Therefore, a systems biology approach to analysing cell cycle transitions identifies the splicing protein, SAP145 as rate-limiting for the G1 →S phase cell cycle transition but not for the transition from G0→G1.

scholarly journals Acetylation of Mammalian ADA3 Is Required for Its Functional Roles in Histone Acetylation and Cell Proliferation

2016 ◽  
Vol 36 (19) ◽  
pp. 2487-2502 ◽  
Author(s):  
Shakur Mohibi ◽  
Shashank Srivastava ◽  
Aditya Bele ◽  
Sameer Mirza ◽  
Hamid Band ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Histone Acetylation ◽  
Cell Cycle Progression ◽  
Site Directed Mutagenesis ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Functional Roles ◽  
A Cell ◽  
Cycle Dependent

Alteration/deficiency in activation 3 (ADA3) is an essential component of specific histone acetyltransferase (HAT) complexes. We have previously shown that ADA3 is required for establishing global histone acetylation patterns and for normal cell cycle progression (S. Mohibi et al., J Biol Chem 287:29442–29456, 2012,http://dx.doi.org/10.1074/jbc.M112.378901). Here, we report that these functional roles of ADA3 require its acetylation. We show that ADA3 acetylation, which is dynamically regulated in a cell cycle-dependent manner, reflects a balance of coordinated actions of its associated HATs, GCN5, PCAF, and p300, and a new partner that we define, the deacetylase SIRT1. We use mass spectrometry and site-directed mutagenesis to identify major sites of ADA3 acetylated by GCN5 and p300. Acetylation-defective mutants are capable of interacting with HATs and other components of HAT complexes but are deficient in their ability to restore ADA3-dependent global or locus-specific histone acetylation marks and cell proliferation inAda3-deleted murine embryonic fibroblasts (MEFs). Given the key importance of ADA3-containing HAT complexes in the regulation of various biological processes, including the cell cycle, our study presents a novel mechanism to regulate the function of these complexes through dynamic ADA3 acetylation.

scholarly journals Distinct cell cycle–dependent roles for dynactin and dynein at centrosomes

2002 ◽  
Vol 159 (2) ◽  
pp. 245-254 ◽  
Author(s):  
Nicholas J. Quintyne ◽  
Trina A. Schroer
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Centrosome Duplication ◽  
Cell Cycle Regulators ◽  
Cycle Progression ◽  
Microtubule Array ◽  
Delayed Entry ◽  
Distinct Cell ◽  
Cycle Dependent

Centrosomal dynactin is required for normal microtubule anchoring and/or focusing independently of dynein. Dynactin is present at centrosomes throughout interphase, but dynein accumulates only during S and G2 phases. Blocking dynein-based motility prevents recruitment of dynactin and dynein to centrosomes and destabilizes both centrosomes and the microtubule array, interfering with cell cycle progression during mitosis. Destabilization of the centrosomal pool of dynactin does not inhibit dynein-based motility or dynein recruitment to centrosomes, but instead causes abnormal G1 centriole separation and delayed entry into S phase. The correct balance of centrosome-associated dynactin subunits is apparently important for satisfaction of the cell cycle mechanism that monitors centrosome integrity before centrosome duplication and ultimately governs the G1 to S transition. Our results suggest that, in addition to functioning as a microtubule anchor, dynactin contributes to the recruitment of important cell cycle regulators to centrosomes.

scholarly journals Deregulated expression of E2F-1 induces S-phase entry and leads to apoptosis.

1994 ◽  
Vol 14 (12) ◽  
pp. 8166-8173 ◽  
Author(s):  
B Shan ◽  
W H Lee
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cell Cycle Progression ◽  
Apoptotic Cell ◽  
Expression System ◽  
Critical Role ◽  
S Phase ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Phase Entry

E2F-1, the first gene product identified among a family of E2F transcription factors, is thought to play a critical role in G1/S progression of the cell cycle. Transcriptional activities of E2F are modulated during the cell cycle, mainly by the formation of complexes between E2F and several key regulators of cell cycle such as the retinoblastoma protein and related proteins. To further understand the roles of E2F in the cell cycle progression, we have overexpressed exogenous E2F-1 by using a tetracycline-controlled expression system. We have found that the induced expression of E2F-1 in Rat-2 fibroblasts promotes S-phase entry and subsequently leads to apoptosis. The apoptosis occurs in an E2F-1 dose-dependent manner. Cells resistant to the induction of apoptosis have lost the ability to express exogenous E2F-1. Cells growing in low serum are more sensitive to the E2F-1-mediated cell death. Overexpression of E2F-1 mutants that impair DNA binding or transactivation does not alter cell cycle progression or induce apoptosis. These results define a novel pathway to apoptosis and demonstrate that premature S-phase entry is associated with apoptotic cell death.

scholarly journals Deregulated expression of E2F-1 induces S-phase entry and leads to apoptosis

1994 ◽  
Vol 14 (12) ◽  
pp. 8166-8173 ◽  
Author(s):  
B Shan ◽  
W H Lee
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cell Cycle Progression ◽  
Apoptotic Cell ◽  
Expression System ◽  
Critical Role ◽  
S Phase ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Phase Entry

E2F-1, the first gene product identified among a family of E2F transcription factors, is thought to play a critical role in G1/S progression of the cell cycle. Transcriptional activities of E2F are modulated during the cell cycle, mainly by the formation of complexes between E2F and several key regulators of cell cycle such as the retinoblastoma protein and related proteins. To further understand the roles of E2F in the cell cycle progression, we have overexpressed exogenous E2F-1 by using a tetracycline-controlled expression system. We have found that the induced expression of E2F-1 in Rat-2 fibroblasts promotes S-phase entry and subsequently leads to apoptosis. The apoptosis occurs in an E2F-1 dose-dependent manner. Cells resistant to the induction of apoptosis have lost the ability to express exogenous E2F-1. Cells growing in low serum are more sensitive to the E2F-1-mediated cell death. Overexpression of E2F-1 mutants that impair DNA binding or transactivation does not alter cell cycle progression or induce apoptosis. These results define a novel pathway to apoptosis and demonstrate that premature S-phase entry is associated with apoptotic cell death.

scholarly journals Fungal zygote survival and ploidy maintenance rely on cell cycle-dependent and independent mating blocks

2020 ◽  
Author(s):  
Aleksandar Vještica ◽  
Melvin Bérard ◽  
Gaowen Liu ◽  
Laura Merlini ◽  
Pedro Junior Nkosi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Genome Stability ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Cycle Progression ◽  
Mating Behaviors ◽  
Cycle Dependent ◽  
Necessary And Sufficient ◽  
Meiotic Cycle

AbstractTo ensure genome stability, sexually reproducing organisms require that mating brings together exactly two haploid gametes and that meiosis occurs only in diploid zygotes. In the fission yeast Schizosaccharomyces pombe, fertilization triggers the Mei3-Pat1-Mei2 signaling cascade, which represses subsequent mating and initiates meiosis. Here, we establish a degron system to specifically degrade proteins post-fusion and demonstrate that mating blocks not only safeguard zygote ploidy but also prevent lysis caused by aberrant fusion attempts. Using long-term imaging and flow-cytometry approaches, we identify previously unrecognized and independent roles for Mei3 and Mei2 in zygotes. We show that Mei3 promotes premeiotic S-phase independently of Mei2 and that cell cycle progression is both necessary and sufficient to reduce zygotic mating behaviors. Mei2 imposes the meiotic program and promotes the meiotic cycle, but also blocks mating behaviors independently of Mei3 and cell cycle progression. Thus, we find that fungi preserve zygote ploidy and survival by at least two mechanisms where the zygotic fate imposed by Mei2 and the cell cycle re-entry triggered by Mei3 synergize to prevent zygotic mating.

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