The Rate of Cell Growth Is Regulated by Purine Biosynthesis via ATP Production and G1 to S Phase Transition

Kondo, Maki; Yamaoka, Takashi; Honda, Soichi; Miwa, Yoshiro; Katashima, Rumi; Moritani, Maki; Yoshimoto, Katsuhiko; Hayashi, Yoshio; Itakura, Mitsuo

doi:10.1093/oxfordjournals.jbchem.a022730

Cited by 71 publications

(59 citation statements)

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“…Previous findings have demonstrated that de novo purine biosynthesis is closely related to the cell cycle (19,20,25,(30)(31)(32)(33). Studies of other enzyme complexes have suggested that the assembly or disassembly of an enzyme cluster may be correlated with cellular events, such as developmental cues or metabolic states of the cell (33); for example, the replitase, a six-enzyme complex involved in DNA replication, has been shown to exist only during S phase (34).…”

Section: Discussionmentioning

confidence: 99%

“…The presence of this protein assembly and its putative function(s) clearly suggest that the spatial organization of pathway enzymes into purinosomes within a cell play an important role in meeting the cellular demand for purines (18). Although many studies have implied up-regulation of the de novo purine biosynthetic pathway during cell cycle progression (14,(19)(20)(21), here we used time-lapse microscopy to determine whether a correlation exists between the cell cycle stage and the number of cells with purinosomes or the cells' purinosome content. Two different cell types, HeLa and LND cells, were used, with the latter deficient in purine salvage, to assess the effect of increased demand on the de novo pathway for purine biosynthesis and the attendant consequences for purinosome assembly.…”

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confidence: 99%

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Purinosome formation as a function of the cell cycle

Chan¹,

Zhao

Pugh

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The de novo purine biosynthetic pathway relies on six enzymes to catalyze the conversion of phosphoribosylpyrophosphate to inosine 5′-monophosphate. Under purine-depleted conditions, these enzymes form a multienzyme complex known as the purinosome. Previous studies have revealed the spatial organization and importance of the purinosome within mammalian cancer cells. In this study, time-lapse fluorescence microscopy was used to investigate the cell cycle dependency on purinosome formation in two cell models. Results in HeLa cells under purine-depleted conditions demonstrated a significantly higher number of cells with purinosomes in the G 1 phase, which was further confirmed by cell synchronization. HGPRT-deficient fibroblast cells also exhibited the greatest purinosome formation in the G 1 phase; however, elevated levels of purinosomes were also observed in the S and G 2 /M phases. The observed variation in cell cycle-dependent purinosome formation between the two cell models tested can be attributed to differences in purine biosynthetic mechanisms. Our results demonstrate that purinosome formation is closely related to the cell cycle.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Purinosome formation as a function of the cell cycle

Chan¹,

Zhao

Pugh

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Decreased AdoMet synthesis alters methylation patterns in CpG islands in DNA and can result in histone hypomethylation, which can alter gene expression (2). Proliferating cells also require the de novo synthesis of purines to maintain rates of DNA synthesis (14).…”

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confidence: 99%

Mthfd1 Is an Essential Gene in Mice and Alters Biomarkers of Impaired One-carbon Metabolism

MacFarlane

Perry

Girnary

et al. 2009

Journal of Biological Chemistry

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Cytoplasmic folate-mediated one carbon (1C) metabolism functions to carry and activate single carbons for the de novo synthesis of purines, thymidylate, and for the remethylation of homocysteine to methionine. C1 tetrahydrofolate (THF) synthase, encoded by Mthfd1, is an entry point of 1Cs into folate metabolism through its formyl-THF synthetase (FTHFS) activity that catalyzes the ATP-dependent conversion of formate and THF to 10-formyl-THF. Disruption of FTHFS activity by the insertion of a gene trap vector into the Mthfd1 gene results in embryonic lethality in mice. Mthfd1 gt/؉ mice demonstrated lower hepatic adenosylmethionine levels, which is consistent with formate serving as a source of 1Cs for cellular methylation reactions. Surprisingly, Mthfd1 gt/؉ mice exhibited decreased levels of uracil in nuclear DNA, indicating enhanced de novo thymidylate synthesis, and suggesting that serine hydroxymethyltransferase and FTHFS compete for a limiting pool of unsubstituted THF. This study demonstrates the essentiality of the Mthfd1 gene and indicates that formate-derived 1Cs are utilized for de novo purine synthesis and the remethylation of homocysteine in liver. Further, the depletion of cytoplasmic FTHFS activity enhances thymidylate synthesis, affirming the competition between thymidylate synthesis and homocysteine remethylation for THF cofactors. Folate-mediated one-carbon (1C)3 metabolism is compartmentalized in the cytoplasm, mitochondria, and nucleus of mammalian cells (1). In the cytoplasm, 1C metabolism functions to carry and chemically activate single carbons for the de novo synthesis of purines, thymidylate, and for the remethylation of homocysteine to methionine (2) (see Fig. 1). Methionine can be adenosylated to form S-adenosylmethionine (AdoMet), the major cellular methyl group donor required for the methylation of DNA, RNA, histones, small molecules, and lipids. Nuclear 1C metabolism functions to synthesize thymidylate from dUMP and serine during S phase through the small ubiquitin-like modifier-dependent translocation of cytoplasmic serine hydroxymethyltransferase (cSHMT), dihydrofolate reductase, and thymidylate synthase into the nucleus (3).Serine, through its conversion to glycine by SHMT, is a primary source of 1Cs for nucleotide and methionine synthesis (4). SHMT generates 1Cs in the cytoplasm, mitochondria, and nucleus, although the generation of 1Cs through SHMT activity in the cytoplasm is not essential in mice, indicating the essentiality of mitochondria-derived 1Cs for cytoplasmic 1C metabolism (5). In mitochondria, the hydroxymethyl group of serine and the C2 carbon of glycine are transferred to tetrahydrofolate (THF) to generate 5,10-methylene-THF by the mitochondrial isozyme of SHMT and the glycine cleavage system, respectively (6). The 1C carried by methylene-THF is oxidized and hydrolyzed to generate formate by the NAD-dependent methylene-

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“…This tetramer may be a complex of mhATase subunits and hamster ATase subunits inactivated by a mutation in CHO ade Ϫ A cells because hamster ATase was always found in the form of tetramers, even in the presence of PRPP, and because the less common tetrameric forms of hATase and mhATase were detected along with the major dimeric forms in the presence of PRPP (data not shown). 2 Mutual Regulation of de Novo and Salvage Pathways-Purine nucleotides are synthesized preferentially by the salvage pathway as long as hypoxanthine is available, with concomitant inhibition of the de novo pathway for sparing the energy expenditure required for de novo synthesis (1,11). In Ϫ A ϩ mhATase cells, the suppression of the de novo pathway by the salvage pathway was strongly inhibited even in the presence of 2 T. Yamaoka and M. Itakura, unpublished data.…”

Section: Discussionmentioning

confidence: 99%

“…We previously reported that purine de novo synthesis is a determinant of intracellular ATP concentration and promotes G 1 to S phase transition in the cell cycle, i.e. the initiation of DNA synthesis (11). Therefore, ATase and its feedback inhibition probably regulate DNA and protein syntheses through ATP production.…”

Section: Contributions Of Atase and Its Feedback Regulation To Varioumentioning

confidence: 99%

Feedback Inhibition of Amidophosphoribosyltransferase Regulates the Rate of Cell Growth via Purine Nucleotide, DNA, and Protein Syntheses

Yamaoka¹,

Yano

Kondo

et al. 2001

Journal of Biological Chemistry

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To clarify the contributions of amidophosphoribosyltransferase (ATase) and its feedback regulation to the rates of purine de novo synthesis, DNA synthesis, protein synthesis, and cell growth, mutated human ATase (mhATase) resistant to feedback inhibition by purine ribonucleotides was engineered by site-directed mutagenesis and expressed in CHO ade ؊ A cells (an ATasedeficient cell line of Chinese hamster ovary fibroblasts) and in transgenic mice (mhATase-Tg mice). In Chinese hamster ovary transfectants with mhATase, the following parameters were examined: ATase activity and its subunit structure, the metabolic rates of de novo and salvage pathways, DNA and protein synthesis rates, and the rate of cell growth. In mhATase-Tg mice, ATase activity in the liver and spleen, the metabolic rate of the de novo pathway in the liver, serum uric acid concentration, urinary excretion of purine derivatives, and T lymphocyte proliferation by phytohemagglutinin were examined. We concluded the following. 1) ATase and its feedback inhibition regulate not only the rate of purine de novo synthesis but also DNA and protein synthesis rates and the rate of cell growth in cultured fibroblasts. 2) Suppression of the de novo pathway by the salvage pathway is mainly due to the feedback inhibition of ATase by purine ribonucleotides produced via the salvage pathway, whereas the suppression of the salvage pathway by the de novo pathway is due to consumption of 5-phosphoribosyl 1-pyrophosphate by the de novo pathway. 3) The feedback inhibition of ATase is more important for the regulation of the de novo pathway than that of 5-phosphoribosyl 1-pyrophosphate synthetase. 4) ATase superactivity leads to hyperuricemia and an increased bromodeoxyuridine incorporation in T lymphocytes stimulated by phytohemagglutinin.Purine nucleotides are synthesized both via the de novo pathway and via the salvage pathway and are vital for cell functions and cell proliferation through DNA and RNA syntheses and ATP energy supply. Amidophosphoribosyltransferase (ATase) 1 is the rate-limiting enzyme in the de novo pathway of purine ribonucleotide synthesis (1) and is regulated by feedback inhibition by AMP and GMP. Hypoxanthine (Hx) and hypoxanthine guanine phosphoribosyltransferase (HPRT) are the most important substrate and enzyme, respectively, of the salvage pathway (1). The Lesch-Nyhan syndrome is caused by a complete deficiency of HPRT. Although patients with this syndrome show hyperuricemia with accelerated de novo purine synthesis, the mechanism of activation of the de novo pathway is not fully understood.In a previous study, we demonstrated that the expression level of ATase limits the growth rate of cultured fibroblasts, and purine salvage strongly inhibits purine de novo synthesis (1). Two mechanisms by which the salvage pathway inhibits the de novo pathway were presumed. 1) Consumption of 5-phosphoribosyl 1-pyrophosphate (PRPP) by the salvage pathway decreases the activity of the de novo pathway because PRPP is the common source of both pathways. 2) Purin...

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The Rate of Cell Growth Is Regulated by Purine Biosynthesis via ATP Production and G1 to S Phase Transition

Cited by 71 publications

References 0 publications

Purinosome formation as a function of the cell cycle

Purinosome formation as a function of the cell cycle

Mthfd1 Is an Essential Gene in Mice and Alters Biomarkers of Impaired One-carbon Metabolism

Feedback Inhibition of Amidophosphoribosyltransferase Regulates the Rate of Cell Growth via Purine Nucleotide, DNA, and Protein Syntheses

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