scholarly journals The biosynthesis of phospholipids is linked to the cell cycle in a model eukaryote

2021 ◽  
Author(s):  
Milada Vítová ◽  
Vojtěch Lanta ◽  
Mária Čížková ◽  
Martin Jakubec ◽  
Frode Rise ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Relative Abundance ◽  
De Novo ◽  
Lipid Fraction ◽  
Transcriptome Profile ◽  
Kennedy Pathway ◽  
Form Part ◽  
Replication Phase ◽  
Choline Phosphate ◽  
Ethanolamine Phosphate

AbstractThe structural challenges faced by eukaryotic cells through the cell cycle are key for understanding cell viability and proliferation. In this study, we tested the hypothesis that the biosynthesis of structural lipids is linked to the cell cycle. If true, this would suggest that the cell’s structure would form part the control of the cell cycle. Lipidomics (31P NMR and MS), proteomics (Western immunoblotting) and transcriptomics (RT-qPCR) techniques were used to profile the lipid fraction and characterise aspects of its metabolism at seven stages of the cell cycle of the model eukaryote, Desmodesmus quadricauda. We found considerable, transient increases in the abundance of phosphatidylethanolamine during the G1 phase (+35%, ethanolamine phosphate cytidylyltransferase increased 2·5×) and phosphatidylglycerol over the G1/pre-replication phase boundary (+100%, phosphatidylglycerol synthase increased 22×). The relative abundance of phosphatidylcholine fell by ~35% during the G1. N-Methyl transferases for the conversion of phosphatidylethanolamine into phosphatidylcholine were not found in the de novo transcriptome profile, though a choline phosphate transferase was found, suggesting that the Kennedy pathway is the principal route for the synthesis of PC. The fatty acid profiles of the four most abundant lipids suggested that these lipids were not generally converted between one another. The relative abundance of both phosphatidylinositol and its synthase remained constant despite an eightfold increase in cell volume. We conclude that the biosynthesis of the three most abundant structural phospholipids is linked to the cell cycle in D. quadricauda.

scholarly journals De novo synthesis of phosphatidylcholine is essential for the promastigote but not amastigote stage in Leishmania major

2020 ◽  
Author(s):  
Samrat Moitra ◽  
Somrita Basu ◽  
Mattie Pawlowic ◽  
Fong-fu Hsu ◽  
Kai Zhang
Keyword(s):  
Culture Medium ◽  
Leishmania Major ◽  
De Novo ◽  
Total Lipids ◽  
De Novo Synthesis ◽  
Targeted Deletion ◽  
Amastigote Stage ◽  
Kennedy Pathway ◽  
Choline Phosphate

ABSTRACTPhosphatidylcholine (PC) is the most abundant type of phospholipids in eukaryotes constituting ~30% of total lipids in Leishmania. PC synthesis mainly occurs via the choline branch of the Kennedy pathway (choline ⇒ choline-phosphate ⇒ CDP-choline ⇒ PC) and the N-methylation of phosphatidylethanolamine (PE). In addition, Leishmania parasites can acquire PC and other lipids from the host or culture medium. In this study, we assessed the function and essentiality of choline ethanolamine phosphotransferase (CEPT) in Leishmania major which is responsible for the final step of the de novo synthesis of PC and PE. Our data indicate that CEPT is localized in the endoplasmic reticulum and possesses the activity to generate PC from CDP-choline and diacylglycerol. Targeted deletion of CEPT is only possible in the presence of an episomal CEPT gene in the promastigote stage of L. major. These chromosomal null parasites require the episomal expression of CEPT to survive in culture, confirming its essentiality during the promastigote stage. In contrast, during in vivo infection of BALB/c mice, these chromosomal null parasites appeared to lose the episomal copy of CEPT while maintaining normal levels of virulence, replication and cellular PC. Therefore, while the de novo synthesis of PC/PE is indispensable for the proliferation of promastigotes, intracellular amastigotes appear to acquire most of their lipids through salvage and remodeling.

scholarly journals De Novo Synthesis of Phosphatidylcholine Is Essential for the Promastigote But Not Amastigote Stage in Leishmania major

2021 ◽  
Vol 11 ◽  
Author(s):  
Samrat Moitra ◽  
Somrita Basu ◽  
Mattie Pawlowic ◽  
Fong-fu Hsu ◽  
Kai Zhang
Keyword(s):  
Culture Medium ◽  
Leishmania Major ◽  
De Novo ◽  
Total Lipids ◽  
De Novo Synthesis ◽  
Targeted Deletion ◽  
Amastigote Stage ◽  
Kennedy Pathway ◽  
Choline Phosphate

Phosphatidylcholine (PC) is the most abundant type of phospholipids in eukaryotes constituting ~30% of total lipids in Leishmania. PC synthesis mainly occurs via the choline branch of the Kennedy pathway (choline ⇒ choline-phosphate ⇒ CDP-choline ⇒ PC) and the N-methylation of phosphatidylethanolamine (PE). In addition, Leishmania parasites can acquire PC and other lipids from the host or culture medium. In this study, we assessed the function and essentiality of choline ethanolamine phosphotransferase (CEPT) in Leishmania major which is responsible for the final step of the de novo synthesis of PC and PE. Our data indicate that CEPT is localized in the endoplasmic reticulum and possesses the activity to generate PC from CDP-choline and diacylglycerol. Targeted deletion of CEPT is only possible in the presence of an episomal CEPT gene in the promastigote stage of L. major. These chromosomal null parasites require the episomal expression of CEPT to survive in culture, confirming its essentiality during the promastigote stage. In contrast, during in vivo infection of BALB/c mice, these chromosomal null parasites appeared to lose the episomal copy of CEPT while maintaining normal levels of virulence, replication and cellular PC. Therefore, while the de novo synthesis of PC/PE is indispensable for the proliferation of promastigotes, intracellular amastigotes appear to acquire most of their lipids through salvage and remodeling.

Abstract 396: Regulation of Cardiomyocyte Proliferation by the Hippo Pathway and Dystrophin Complex

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Yuka Morikawa ◽  
John Leach ◽  
Todd Heallen ◽  
Ge Tao ◽  
James F Martin
Keyword(s):  
Cell Cycle ◽  
Muscular Dystrophy ◽  
Dna Synthesis ◽  
De Novo ◽  
Hippo Pathway ◽  
Myocardial Damage ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Heart Repair ◽  
The Hippo Pathway

Regeneration in mammalian hearts is limited due to the extremely low renewal rate of cardiomyocytes and their inability to reenter the cell cycle. In rodent hearts, endogenous regenerative capacity exists during development but is rapidly repressed after birth, at which time growth is by hypertrophy. During the developmental and neonatal periods, heart regeneration occurs through proliferation of pre-existing cardiomyocytes. Our approach of activating heart regeneration is to uncover the mechanisms responsible for repression of cardiomyocyte proliferation. The Hippo pathway controls heart size by repressing cardiomyocyte proliferation during development. By deleting Salv , a modulator of the Hippo pathway, we found that myocardial damage in postnatal and adult hearts was repaired both anatomically and functionally. This heart repair occurred primary through proliferation of preexisting cardiomyocytes. During repair, cardiomyocytes reenter the cell cycle; de novo DNA synthesis, karyokinesis, and cytokinesis all take place. The dystrophin glycoprotein complex (DGC) is essential for muscle maintenance by anchoring the cytoskeleton and extracellular matrix. Disruption of the DGC results in muscular dystrophies, including Duchenne muscular dystrophy, resulting in both skeletal and cardiac myopathies. Recently the DGC was shown to regulate cardiomyocyte proliferation and we found that the DGC and the Hippo pathway components directly interact. To address if the DGC and the Hippo pathway coordinately regulate cardiomyocyte proliferation, we conditionally deleted Salv in the mouse model of muscular dystrophy, the mdx line. We found that simultaneous disruption of both the DGC and Hippo pathway leads an increased de novo DNA synthesis and cytokinesis in cardiomyocytes after heart damage. Our findings provide new insights into the mechanisms leading to heart repair through proliferation of endogenous cardiomyocytes.

scholarly journals Avidin inhibits PHA-induced human peripheral blood mononuclear cell proliferation

2016 ◽  
Vol 25 (1) ◽  
pp. 19-24
Author(s):  
Cicia Firakania ◽  
Indra G. Mansur ◽  
Sri W.A. Jusman ◽  
Mohamad Sadikin
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Peripheral Blood Mononuclear Cell ◽  
Mononuclear Cell ◽  
Peripheral Blood ◽  
De Novo ◽  
Human Peripheral Blood ◽  
Interleukin 2 ◽  
Peripheral Blood Mononuclear ◽  
Cell Proliferation Inhibition

Background: Cell proliferation occurs not only in normal but also in cancer cells. Most of cell proliferation inhibition can be done by inhibiting the DNA synthesis, notably by intervening the formation of purine or pyrimidine. In purine de novo synthesis, it was assumed that biotin plays a role as a coenzyme in carboxylation reaction, one of the pivotal steps in the purine de novo pathways. The aim of this study was to see the avidin potency to bind biotin and inhibit mitosis.Methods: Peripheral blood mononuclear cell (PBMC) was cultured in RPMI-1640 medium and stimulated by phytohemagglutinin (PHA) in the presence or absence of interleukin-2 (IL-2), with or without avidin. The effect of avidin addition was observed at 24, 48, and 72 hours for cell proliferation, viability, and cell cycle. Statistical analysis was done by one-way ANOVA.Results: Avidin inhibited cell proliferation and viability in culture under stimulation by PHA with and without IL-2. Cell cycle analysis showed that avidin arrested the progression of PBMC after 72 hours of culture. Most cells were found in G0/G1 phase.Conclusion: Inhibition of biotin utilization by avidin binding can halt cell proliferation.

DE NOVO PURINE NUCLEOTIDE SYNTHESIS DURING CELL CYCLE

1981 ◽  
Vol 9 (2) ◽  
pp. 300P-300P
Author(s):  
L. THUILLIER ◽  
F. GARREAU ◽  
P. CARTIER
Keyword(s):  
Cell Cycle ◽  
De Novo ◽  
Purine Nucleotide ◽  
Nucleotide Synthesis

scholarly journals Imaging the fate of histone Cse4 reveals de novo replacement in S phase and subsequent stable residence at centromeres

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Jan Wisniewski ◽  
Bassam Hajj ◽  
Jiji Chen ◽  
Gaku Mizuguchi ◽  
Hua Xiao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Elevated Temperatures ◽  
De Novo ◽  
Histone H3 ◽  
S Phase ◽  
Nuclear Accumulation ◽  
Histone H3 Variant ◽  
Functionally Impaired ◽  
Cell Cycle Dynamics ◽  
Cell Lethality

The budding yeast centromere contains Cse4, a specialized histone H3 variant. Fluorescence pulse-chase analysis of an internally tagged Cse4 reveals that it is replaced with newly synthesized molecules in S phase, remaining stably associated with centromeres thereafter. In contrast, C-terminally-tagged Cse4 is functionally impaired, showing slow cell growth, cell lethality at elevated temperatures, and extra-centromeric nuclear accumulation. Recent studies using such strains gave conflicting findings regarding the centromeric abundance and cell cycle dynamics of Cse4. Our findings indicate that internally tagged Cse4 is a better reporter of the biology of this histone variant. Furthermore, the size of centromeric Cse4 clusters was precisely mapped with a new 3D-PALM method, revealing substantial compaction during anaphase. Cse4-specific chaperone Scm3 displays steady-state, stoichiometric co-localization with Cse4 at centromeres throughout the cell cycle, while undergoing exchange with a nuclear pool. These findings suggest that a stable Cse4 nucleosome is maintained by dynamic chaperone-in-residence Scm3.

scholarly journals Recombinant human granulocyte-macrophage colony-stimulating factor in combination with standard induction chemotherapy in de novo acute myeloid leukemia

Blood ◽  
1991 ◽  
Vol 77 (4) ◽  
pp. 700-711 ◽  
Author(s):  
P Bettelheim ◽  
P Valent ◽  
M Andreeff ◽  
A Tafuri ◽  
J Haimi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Induction Chemotherapy ◽  
De Novo ◽  
Gm Csf ◽  
Cell Counts ◽  
Macrophage Colony Stimulating Factor ◽  
De Novo Aml ◽  
Macrophage Colony ◽  
Stimulating Factor

Abstract Based on in vitro data suggesting that recombinant human granulocyte- macrophage colony-stimulating factor (rhGM-CSF) is capable of stimulating acute myeloid leukemia (AML) blast cells to become more sensitive to cell-cycle-specific drugs we conducted a phase I/II study in de novo AML patients (pts). rhGM-CSF (250 micrograms/m2/d, continuous intravenous infusion) was administered in 18 pts suffering from de novo AML in combination with standard induction chemotherapy (3 + 7 = daunorubicin 45 mg/m2 days 1 through 3, cytosine-arabinoside [Ara- C] 200 mg/m2 continuous infusion days 1 through 7). GM-CSF was started 48 or 24 hours before chemotherapy (prephase) in 14 pts. In four pts with high white blood cell counts (WBC) rhGM-CSF was started after chemotherapy-induced cell reduction (WBC less than 30,000/mm3). During prephase GM-CSF induced an increase in neutrophil and blast cell counts in 13 of 14 and 10 of 14 pts, respectively. In vivo recruitment of leukemic cells into drug-sensitive phases of the cell cycle could be demonstrated by multiparameter cell-cycle analyses in peripheral blood (n = 7) and bone marrow (n = 4) specimens. On day 14, complete aplasia was evident in 17 of 18 pts. GM-CSF was administered until recovery from chemotherapy-induced myelosuppression (absolute neutrophil counts, [ANC] greater than 500/mm3). Fifteen pts (83%) achieved complete remission, 12 did so with one cycle. A shorter duration of neutropenia was evident in these pts compared with historical controls (n = 39), (ANC greater than 500/mm3, day 22.5 +/- 3.4 v 25.2 +/- 3.7, P less than .05). Three pts achieved complete remission after a second cycle (same combination of rhGM-CSF and 3 + 7). Two pts died during bone marrow aplasia because of invasive pulmonary aspergillosis. Clinical side effects possibly related to GM-CSF, mainly fever, diarrhea, and weight gain were mild and tolerable (World Health Organization toxicity grade less than or equal to 2). Together, rhGM-CSF recruits kinetically quiescient AML cells in vivo to enter drug-sensitive phases of the cell cycle and promotes early myeloid recovery from aplasia after exposure to standard induction chemotherapy for AML.

scholarly journals Elacestrant (RAD1901) exhibits anti-tumor activity in multiple ER+ breast cancer models resistant to CDK4/6 inhibitors

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Hitisha K. Patel ◽  
Nianjun Tao ◽  
Kyung-Min Lee ◽  
Mariela Huerta ◽  
Heike Arlt ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Estrogen Receptor ◽  
De Novo ◽  
Single Agent ◽  
Metastatic Breast ◽  
Cancer Resistance ◽  
Treatment Paradigm ◽  
Anti Tumor Activity

Abstract Background Addition of CDK4/6 inhibitors (CDK4/6i) to endocrine therapy significantly increased progression-free survival, leading to their approval and incorporation into the metastatic breast cancer treatment paradigm. With these inhibitors being routinely used for patients with advanced estrogen receptor-positive (ER+) breast cancer, resistance to these agents and its impact on subsequent therapy needs to be understood. Considering the central role of ER in driving the growth of ER+ breast cancers, and thus endocrine agents being a mainstay in the treatment paradigm, the effects of prior CDK4/6i exposure on ER signaling and the relevance of ER-targeted therapy are important to investigate. The objective of this study was to evaluate the anti-tumor activity of elacestrant, a novel oral selective estrogen receptor degrader (SERD), in preclinical models of CDK4/6i resistance. Methods Elacestrant was evaluated as a single agent, and in combination with alpelisib or everolimus, in multiple in vitro models and patient-derived xenografts that represent acquired and “de novo” CDK4/6i resistance. Results Elacestrant demonstrated growth inhibition in cells resistant to all three approved CDK4/6i (palbociclib, abemaciclib, ribociclib) in both ESR1 wild-type and mutant backgrounds. Furthermore, we demonstrated that elacestrant, as a single agent and in combination, inhibited growth of patient-derived xenografts that have been derived from a patient previously treated with a CDK4/6i or exhibit de novo resistance to CDK4/6i. While the resistant lines demonstrate distinct alterations in cell cycle modulators, this did not affect elacestrant’s anti-tumor activity. In fact, we observe that elacestrant downregulates several key cell cycle players and halts cell cycle progression in vitro and in vivo. Conclusions We demonstrate that breast cancer tumor cells continue to rely on ER signaling to drive tumor growth despite exposure to CDK4/6i inhibitors. Importantly, elacestrant can inhibit this ER-dependent growth despite previously reported mechanisms of CDK4/6i resistance observed such as Rb loss, CDK6 overexpression, upregulated cyclinE1 and E2F1, among others. These data provide a scientific rationale for the evaluation of elacestrant in a post-CDK4/6i patient population. Additionally, elacestrant may also serve as an endocrine backbone for rational combinations to combat resistance.

scholarly journals Locations and contributions of the phosphotransferases EPT1 and CEPT1 to the biosynthesis of ethanolamine phospholipids

2020 ◽  
Vol 61 (8) ◽  
pp. 1221-1231 ◽  
Author(s):  
Yasuhiro Horibata ◽  
Hiromi Ando ◽  
Hiroyuki Sugimoto
Keyword(s):  
Fatty Acids ◽  
De Novo ◽  
Brefeldin A ◽  
Hek293 Cells ◽  
Intracellular Location ◽  
De Novo Biosynthesis ◽  
Substrate Preferences ◽  
Ethanolamine Phosphate ◽  
Immunohistochemical Analyses

The final step of the CDP-ethanolamine pathway is catalyzed by ethanolamine phosphotransferase 1 (EPT1) and choline/EPT1 (CEPT1). These enzymes are likely involved in the transfer of ethanolamine phosphate from CDP-ethanolamine to lipid acceptors such as 1,2-diacylglycerol (DAG) for PE production and 1-alkyl-2-acyl-glycerol (AAG) for the generation of 1-alkyl-2-acyl-glycerophosphoethanolamine. Here, we investigated the intracellular location and contribution to ethanolamine phospholipid (EP) biosynthesis of EPT1 and CEPT1 in HEK293 cells. Immunohistochemical analyses revealed that EPT1 localizes to the Golgi apparatus and CEPT1 to the ER. We created EPT1-, CEPT1-, and EPTI-CEPT1-deficient cells, and labeling of these cells with radio- or deuterium-labeled ethanolamine disclosed that EPT1 is more important for the de novo biosynthesis of 1-alkenyl-2-acyl-glycerophosphoethanolamine than is CEPT1. EPT1 also contributed to the synthesis of PE species containing the fatty acids 36:1, 36:4, 38:5, 38:4, 38:3, 40:6, 40:5, and 40:4. In contrast, CEPT1 was important for PE formation from shorter fatty acids such as 32:2, 32:1, 34:2, and 34:1. Brefeldin A treatment did not significantly affect the levels of the different PE species, indicating that the subcellular localization of the two enzymes is not responsible for their substrate preferences. In vitro enzymatic analysis revealed that EPT1 prefers AAG 16–20:4 > DAG 18:0–20:4 > DAG 16:0–18:1 = AAG 16–18:1 as lipid acceptors and that CEPT1 greatly prefers DAG 16:0–18:1 to other acceptors. These results suggest that EPT1 and CEPT1 differ in organelle location and are responsible for the biosynthesis of distinct EP species.

scholarly journals Microtubule Cytoskeleton Remodeling by Acentriolar Microtubule-organizing Centers at the Entry and Exit from Mitosis in Drosophila Somatic Cells

2009 ◽  
Vol 20 (11) ◽  
pp. 2796-2808 ◽  
Author(s):  
Sara Moutinho-Pereira ◽  
Alain Debec ◽  
Helder Maiato
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
De Novo ◽  
Animal Cell ◽  
Somatic Cells ◽  
Spindle Assembly ◽  
Entry And Exit ◽  
Down Regulation ◽  
Microtubule Organizing Centers ◽  
Cytoskeleton Remodeling

Cytoskeleton microtubules undergo a reversible metamorphosis as cells enter and exit mitosis to build a transient mitotic spindle required for chromosome segregation. Centrosomes play a dominant but dispensable role in microtubule (MT) organization throughout the animal cell cycle, supporting the existence of concurrent mechanisms that remain unclear. Here we investigated MT organization at the entry and exit from mitosis, after perturbation of centriole function in Drosophila S2 cells. We found that several MTs originate from acentriolar microtubule-organizing centers (aMTOCs) that contain γ-tubulin and require Centrosomin (Cnn) for normal architecture and function. During spindle assembly, aMTOCs associated with peripheral MTs are recruited to acentriolar spindle poles by an Ncd/dynein-dependent clustering mechanism to form rudimentary aster-like structures. At anaphase onset, down-regulation of CDK1 triggers massive formation of cytoplasmic MTs de novo, many of which nucleated directly from aMTOCs. CDK1 down-regulation at anaphase coordinates the activity of Msps/XMAP215 and the kinesin-13 KLP10A to favor net MT growth and stability from aMTOCs. Finally, we show that microtubule nucleation from aMTOCs also occurs in cells containing centrosomes. Our data reveal a new form of cell cycle–regulated MTOCs that contribute for MT cytoskeleton remodeling during mitotic spindle assembly/disassembly in animal somatic cells, independently of centrioles.

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