1
|
Jiang T, Dai S, Yi Y, Liu Y, Zhang S, Luo M, Wang H, Xu D. The combination of hprt and gapdh is the best compound reference genes in the fetal rat hippocampus. Dev Neurobiol 2020; 80:229-238. [PMID: 32875725 DOI: 10.1002/dneu.22779] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/11/2020] [Accepted: 08/24/2020] [Indexed: 11/06/2022]
Abstract
Hippocampus, as an important organ of central memory storage and spatial orientation, has been studied increasingly in recent years. The expression of reference genes in the hippocampus of adult rats, which are commonly used in the quantitative real-time polymerase chain reaction (qRT-PCR), is unstable in the fetal hippocampus and may not be suitable for the fetal period. Therefore, this study intends to screen and determine the optimal compound reference genes in the fetal rat hippocampus. Based on the literature, we selected five housekeeping genes (HKGs), including glyceraldehyde 3-phosphate dehydrogenase (gapdh), actin beta (β-actin), hypoxanthine phosphoribosyltransferase (hprt), 18s ribosomal RNA (18s rRNA), and cyclophilin B (cypB). We analyzed the expression of them under physiological conditions in the fetal rat hippocampus using BestKeeper, GeNorm, and NormFinder, to select the most stable compound reference genes. Furthermore, to verify the stability of the compound reference genes, we analyzed the expression of reference genes in the fetal rat hippocampus under the pathological model of prenatal dexamethasone exposure (PDE). Finally, we evaluated the accuracy of compound reference genes through detecting the expression of fetal rat hippocampal brain-derived neurotrophic factor (BDNF) under PDE model. This study determined that the combination of gapdh and hprt was the most stable and suitable compound reference genes in the fetal rat hippocampus. There was no significant difference between male and female fetal rats. We provided the support of accurate and reliable reference genes for the further study of diseases related to the fetal hippocampus.
Collapse
Affiliation(s)
- Tao Jiang
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Shiyun Dai
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Yiwen Yi
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Yi Liu
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Shuai Zhang
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Mingcui Luo
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China
| | - Hui Wang
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
| | - Dan Xu
- Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
| |
Collapse
|
2
|
Fateev IV, Sinitsina EV, Bikanasova AU, Kostromina MA, Tuzova ES, Esipova LV, Muravyova TI, Kayushin AL, Konstantinova ID, Esipov RS. Thermophilic phosphoribosyltransferases Thermus thermophilus HB27 in nucleotide synthesis. Beilstein J Org Chem 2018; 14:3098-3105. [PMID: 30643587 PMCID: PMC6317416 DOI: 10.3762/bjoc.14.289] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/27/2018] [Indexed: 11/23/2022] Open
Abstract
Phosphoribosyltransferases are the tools that allow the synthesis of nucleotide analogues using multi-enzymatic cascades. The recombinant adenine phosphoribosyltransferase (TthAPRT) and hypoxanthine phosphoribosyltransferase (TthHPRT) from Thermus thermophilus HB27 were expressed in E.coli strains and purified by chromatographic methods with yields of 10-13 mg per liter of culture. The activity dependence of TthAPRT and TthHPRT on different factors was investigated along with the substrate specificity towards different heterocyclic bases. The kinetic parameters for TthHPRT with natural substrates were determined. Two nucleotides were synthesized: 9-(β-D-ribofuranosyl)-2-chloroadenine 5'-monophosphate (2-Сl-AMP) using TthAPRT and 1-(β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine-4-one 5'-monophosphate (Allop-MP) using TthНPRT.
Collapse
Affiliation(s)
- Ilja V Fateev
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Ekaterina V Sinitsina
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Aiguzel U Bikanasova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Maria A Kostromina
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Elena S Tuzova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Larisa V Esipova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Tatiana I Muravyova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Alexei L Kayushin
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Irina D Konstantinova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| | - Roman S Esipov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia
| |
Collapse
|
3
|
Endo T, Noda N, Kuromi Y, Kokura K, Kazuki Y, Oshimura M, Ohbayashi T. Evaluation of an Hprt-Luciferase Reporter Gene on a Mammalian Artificial Chromosome in Response to Cytotoxicity. Yonago Acta Med 2016; 59:174-182. [PMID: 27493490 PMCID: PMC4973025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/17/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Hypoxanthine guanine phosphoribosyltransferase (Hprt) is known as a house-keeping gene, and has been used as an internal control for real-time quantitative RT-PCR and various other methods of gene expression analysis. To evaluate the Hprt mRNA levels as a reference standard, we engineered a luciferase reporter driven by a long Hprt promoter and measured its response to cytotoxicity. METHODS We constructed a reporter vector that harbored a phiC31 integrase recognition site and a mouse Hprt promoter fused with green-emitting luciferase (SLG) coding sequence. The Hprt-SLG vector was loaded onto a mouse artificial chromosome containing a multi-integrase platform using phiC31 integrase in mouse A9 cells. We established three independent clones. RESULTS The established cell lines had similar levels of expression of the Hprt-SLG reporter gene. Hprt-SLG activity increased proportionately under growth conditions and decreased under cytotoxic conditions after blasticidin or cisplatin administration. Similar increases and decreases in the SLG luminescent were observed under growth and cytotoxic conditions, respectively, to those in the fluorescent obtained using the commercially available reagent, alamarBlue. CONCLUSION By employing a reliable and stable expression system in a mammalian artificial chromosome, the activity of an Hprt-SLG reporter can reflect cell numbers under cell growth condition and cell viability in the evaluation of cytotoxic conditions.
Collapse
Affiliation(s)
- Takeshi Endo
- Tottori Industrial Promotion Organization, Tottori 689-1112, Japan
| | - Natsumi Noda
- Tottori Industrial Promotion Organization, Tottori 689-1112, Japan
| | - Yasushi Kuromi
- Tottori Industrial Promotion Organization, Tottori 689-1112, Japan; ‡Division of Laboratory Animal Science, Research Center for Bioscience and Technology, Tottori University, Yonago 683-8503, Japan
| | - Kenji Kokura
- §Chromosome Engineering Research Center, Tottori University, Yonago 683-8503, Japan
| | - Yasuhiro Kazuki
- §Chromosome Engineering Research Center, Tottori University, Yonago 683-8503, Japan; ||Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Tottori University, Yonago 683-8503, Japan; ¶Division of Molecular and Cell Genetics, Department of Molecular and Cellular Biology, School of Life Sciences, Tottori University Faculty of Medicine, Yonago 683-8503, Japan
| | - Mitsuo Oshimura
- §Chromosome Engineering Research Center, Tottori University, Yonago 683-8503, Japan
| | - Tetsuya Ohbayashi
- ‡Division of Laboratory Animal Science, Research Center for Bioscience and Technology, Tottori University, Yonago 683-8503, Japan
| |
Collapse
|
4
|
Dauphinot L, Mockel L, Cahu J, Jinnah HA, Ledroit M, Potier MC, Ceballos-Picot I. Transcriptomic approach to Lesch-Nyhan disease. Nucleosides Nucleotides Nucleic Acids 2015; 33:208-17. [PMID: 24940671 DOI: 10.1080/15257770.2014.880477] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Lesch-Nyhan disease (LND) is an X-linked metabolic disease caused by various mutations in the gene HPRT1 encoding an enzyme of purine metabolism, hypoxanthine guanine phosphoribosyltransferase (HPRT). In its most severe form, LND patients suffer from overproduction of uric acid along with neurological or behavioural difficulties including self-injurious behaviours. To gain more insight into pathogenesis, we compared the transcriptome from human LND fibroblasts to normal human fibroblasts using a microarray with 60,000 probes corresponding to the entire human genome. Using stringent criteria, we identified 25 transcripts whose expression was significantly different between LND and control cells. These genes were confirmed by quantitative RT-PCR to be dysregulated in LND cells. Moreover, bioinformatic analysis of microarray data using gene ontology (GO) highlighted clusters of genes displaying biological processes most significantly affected in LND cells. These affected genes belonged to specific processes such as cell cycle and cell-division processes, metabolic and nucleic acid processes, demonstrating the specific nature of the changes and providing new insights into LND pathogenesis.
Collapse
Affiliation(s)
- Luce Dauphinot
- a CRICM, UPMC Hôpital de la Pitié-Salpêtrière , Paris , France
| | | | | | | | | | | | | |
Collapse
|
5
|
Varela LM, Ortega-Gomez A, Lopez S, Abia R, Muriana FJG, Bermudez B. The effects of dietary fatty acids on the postprandial triglyceride-rich lipoprotein/apoB48 receptor axis in human monocyte/macrophage cells. J Nutr Biochem 2014; 24:2031-9. [PMID: 24231096 DOI: 10.1016/j.jnutbio.2013.07.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 06/10/2013] [Accepted: 07/03/2013] [Indexed: 12/26/2022]
Abstract
Intestinally produced triglyceride-rich lipoproteins (TRL) play an important role in the progression of atherosclerosis. In this study, we investigated the relevance of monounsaturated fatty acid (MUFA) and saturated fatty acid (SFA) in postprandial TRL in affecting the transcriptional activity of the apolipoprotein-B48 receptor (ApoB48R) and its functionality in human monocyte/macrophage cells. Healthy male volunteers were administered four standardized high-fat meals containing butter, high-palmitic sunflower oil, olive oil (ROO) or a mixture of vegetable and fish oils (50 g/m(2) body surface area) to obtain a panel of postprandial TRL with gradual MUFA oleic acid-to-SFA palmitic acid ratios. The increase in this ratio was linearly associated with a decrease of ApoB48R up-regulation and lipid accumulation in THP-1 and primary monocytes. ApoB48R mRNA levels and intracellular triglycerides were also lower in the monocytes from volunteers after the ingestion of the ROO meal when compared to the ingestion of the butter meal. In THP-1 macrophages, the increase in the MUFA oleic acid-to-SFA palmitic acid ratio in the postprandial TRL was linearly correlated with an increase in ApoB48R down-regulation and a decrease in lipid accumulation. We also revealed that the nuclear receptor transcription factors PPARα, PPARβ/δ, and PPARγ and the PPAR-RXR transcriptional complex were involved in sensing the proportion of MUFA oleic acid and SFA palmitic acid, and these were also involved in adjusting the transcriptional activity of ApoB48R. The results of this study support the notion that MUFA-rich dietary fats may prevent excessive lipid accumulation in monocyte/macrophage cells by targeting the postprandial TRL/ApoB48R axis.
Collapse
Affiliation(s)
- Lourdes M Varela
- Laboratory of Cellular and Molecular Nutrition, Instituto de la Grasa (CSIC), 41012 Seville, Spain
| | | | | | | | | | | |
Collapse
|
6
|
Boué J, Basso L, Cenac N, Blanpied C, Rolli-Derkinderen M, Neunlist M, Vergnolle N, Dietrich G. Endogenous regulation of visceral pain via production of opioids by colitogenic CD4(+) T cells in mice. Gastroenterology 2014; 146:166-75. [PMID: 24055279 DOI: 10.1053/j.gastro.2013.09.020] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 09/06/2013] [Accepted: 09/09/2013] [Indexed: 01/16/2023]
Abstract
BACKGROUND & AIMS A dysregulated response of CD4(+) T cells against the microbiota contributes to the development of inflammatory bowel disease. Effector CD4(+) T cells, generated in response to microbe-derived antigens, can reduce somatic inflammatory pain through the local release of opioids. We investigated whether colitogenic CD4(+) T cells that accumulate in the inflamed colon also produce opioids and are able to counteract inflammation-induced visceral pain in mice. METHODS Colitis was induced via transfer of naive CD4(+)CD45RB(high) T cells to immune-deficient mice or by administration of dextran sulfate sodium. Mice without colitis were used as controls. Samples of colon tissue were collected, and production of opioids by immune cells from inflamed intestine was assessed by quantitative polymerase chain reaction and cytofluorometry analyses. The role of intestinal opioid tone in inflammation-induced visceral hypersensitivity was assessed by colorectal distention. RESULTS In mice with T cell- or dextran sulfate sodium-induced colitis, colitogenic CD4(+) T cells (T-helper 1 and Th17 cells) accumulated in the inflamed intestine and expressed a high level of endogenous opioids. In contrast, macrophages and epithelial cells did not express opioids; opioid synthesis in the myenteric plexus was not altered on induction of inflammation. In mice with colitis, the local release of opioids by colitogenic CD4(+) T cells led to significant reduction of inflammation-associated visceral hypersensitivity. CONCLUSIONS In mice, colitogenic Th1 and Th17 cells promote intestinal inflammation and colonic tissue damage but have simultaneous opioid-mediated analgesic activity, thereby reducing abdominal pain.
Collapse
Affiliation(s)
- Jérôme Boué
- INSERM Unité 1043, Toulouse, France; CNRS, U5282, Toulouse, France; Centre de Physiopathologie de Toulouse Purpan, Université de Toulouse UPS, Toulouse, France
| | - Lilian Basso
- INSERM Unité 1043, Toulouse, France; CNRS, U5282, Toulouse, France; Centre de Physiopathologie de Toulouse Purpan, Université de Toulouse UPS, Toulouse, France
| | - Nicolas Cenac
- INSERM Unité 1043, Toulouse, France; CNRS, U5282, Toulouse, France; Centre de Physiopathologie de Toulouse Purpan, Université de Toulouse UPS, Toulouse, France
| | - Catherine Blanpied
- INSERM Unité 1043, Toulouse, France; CNRS, U5282, Toulouse, France; Centre de Physiopathologie de Toulouse Purpan, Université de Toulouse UPS, Toulouse, France
| | - Malvyne Rolli-Derkinderen
- INSERM Unité 913, Nantes, France; Institut des Maladies de l'Appareil Digestif, Université de Nantes, Nantes, France
| | - Michel Neunlist
- INSERM Unité 913, Nantes, France; Institut des Maladies de l'Appareil Digestif, Université de Nantes, Nantes, France
| | - Nathalie Vergnolle
- INSERM Unité 1043, Toulouse, France; CNRS, U5282, Toulouse, France; Centre de Physiopathologie de Toulouse Purpan, Université de Toulouse UPS, Toulouse, France; Department of Pharmacology and Physiology, University of Calgary, Calgary, Alberta, Canada
| | - Gilles Dietrich
- INSERM Unité 1043, Toulouse, France; CNRS, U5282, Toulouse, France; Centre de Physiopathologie de Toulouse Purpan, Université de Toulouse UPS, Toulouse, France.
| |
Collapse
|
7
|
Tanaka Y, Matsuwaki T, Yamanouchi K, Nishihara M. Increased lysosomal biogenesis in activated microglia and exacerbated neuronal damage after traumatic brain injury in progranulin-deficient mice. Neuroscience 2013; 250:8-19. [PMID: 23830905 DOI: 10.1016/j.neuroscience.2013.06.049] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 06/11/2013] [Accepted: 06/21/2013] [Indexed: 01/12/2023]
Abstract
Progranulin (PGRN) is known to play a role in the pathogenesis of neurodegenerative diseases. Recently, it has been demonstrated that patients with the homozygous mutation in the GRN gene present with neuronal ceroid lipofuscinosis, and there is growing evidence that PGRN is related to lysosomal function. In the present study, we investigated the possible role of PGRN in the lysosomes of activated microglia in the cerebral cortex after traumatic brain injury (TBI). We showed that the mouse GRN gene has two possible coordinated lysosomal expression and regulation (CLEAR) sequences that bind to transcription factor EB (TFEB), a master regulator of lysosomal genes. PGRN was colocalized with Lamp1, a lysosomal marker, and Lamp1-positive areas in GRN-deficient (KO) mice were significantly expanded compared with wild-type (WT) mice after TBI. Expression of all the lysosome-related genes examined in KO mice was significantly higher than that in WT mice. The number of activated microglia with TFEB localized to the nucleus was also significantly increased in KO as compared with WT mice. Since the TFEB translocation is regulated by the mammalian target of rapamycin complex 1 (mTORC1) activity in the lysosome, we compared ribosomal S6 kinase 1 (S6K1) phosphorylation that reflects mTORC1 activity. S6K1 phosphorylation in KO mice was significantly lower than that in WT mice. In addition, the number of nissl-positive and fluoro-jade B-positive cells around the injury was significantly decreased and increased, respectively, in KO as compared with WT mice. These results suggest that PGRN localized in the lysosome is involved in the activation of mTORC1, and its deficiency leads to increased TFEB nuclear translocation with a resultant increase in lysosomal biogenesis in activated microglia and exacerbated neuronal damage in the cerebral cortex after TBI.
Collapse
Affiliation(s)
- Y Tanaka
- Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | | | | | | |
Collapse
|
8
|
Francke U, Taggart RT. Assignment of the gene for cytoplasmic superoxide dismutase (Sod-1) to a region of chromosome 16 and of Hprt to a region of the X chromosome in the mouse. Proc Natl Acad Sci U S A 1979; 76:5230-3. [PMID: 291939 PMCID: PMC413114 DOI: 10.1073/pnas.76.10.5230] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In the search for homologous chromosome regions in man and mouse, the locus for cytoplasmic superoxide dismutase (SOD-1; superoxide:superoxide oxidoreductase, EC 1.15.1.1) is of particular interest. In man, the SOD-1 gene occupies the same subregion of chromosome 21 that causes Down syndrome when present in triplicate. Although not obviously implicated in the pathogenesis, SOD-1 is considered to be a biochemical marker for this aneuploid condition. Using a set of 29 mouse-Chinese hamster somatic cell hybrids, we assign Sod-1 to mouse chromosome 16. Isoelectric focusing permits distinction between mouse and Chinese hamster isozymes, and trypsin/Giemsa banding distinguishes mouse from Chinese hamster chromosomes. The mouse fibroblasts used were derived from a male mouse carrying Searle's T(X;16)16H reciprocal translocation in which chromosomes X and 16 have exchanged parts. Analysis of informative hybrids leads to regional assignment of Sod-1 to the distal half of mouse chromosome 16 (16B4 --> ter). Because the Chinese hamster cell line (380) used for cell hybridization is deficient in hypoxanthine phosphoribosyltransferase (HPRT; IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8), that part of the mouse X chromosome carrying the complementing Hprt gene can be identified by selection in hypoxanthine/aminopterin/thymidine medium and counterselection in 8-azaguanine. Mouse Hprt is on the X(T) translocation product containing the proximal region X cen --> XD.
Collapse
|
9
|
Abstract
Mouse A9 cells, deficient in hypoxanthine phosphoribosyltransferase (EC 2.4.2.8), were fused with normal chick erythrocytes and selected in hypoxanthine-aminopterin-thymidine medium for cells with hypoxanthine phosphoribosyltransferase activity. Recovered hybrid cells produced the chick hypoxanthine phosphoribosyltransferase exclusively, as demonstrated by electrophoretic mobility and immunoprecipitation tests, even though no chick chromosomes or chick cell-surface antigens could be identified in the hybrids. Surprisingly, the expression of the chick hypoxanthine phosphoribosyl-transferase activity in the mouse/chick hybrids required the presence of aminopterin in the growth medium; in its absence, enzyme synthesis decreased markedly. Because of the rapid and reversible modulation of hypoxanthine phosphoribosyltransferase activity, the hybrid cells could proliferate equally well in media containing hypoxanthine-aminopterin-thymidine or 8-azaguanine. Cellular selection was definitely ruled out as a possible cause. These results confirm previous reports that specific genetic information can be selectively transferred from one cell to another of a distant species. Furthermore, they demonstrate that an avian gene, whose activity is normally expressed constitutively, can become facultative when integrated into a mammalian cell. This seems to be the first instance where heterologous gene activity has been shown to be reversibly modulated in hybrid cells.
Collapse
|
10
|
Abstract
Purine metabolism has been examined in a clonal line of mouse neuroblastoma cells resistant to the cytotoxic effects of 6-thioguanine. Comparative studies in the resistant and parental lines indicate that the former cells have less than 1% of normal hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) activity. The activities of other enzymes important in the de novo and salvage pathways of purine biosynthesis were not significantly different in the two lines. Hypoxanthine phosphoribosyltransferase deficiency in this neuroblastoma line was associated with increased intracellular concentrations of 5-phosphoribosyl-1-pyrophosphate, an increased rate of purine biosynthesis de novo, and failure to incorporate hypoxanthine, but not adenine, into nucleotides. There are essentially the same alterations in purine metabolism that occur in hypoxanthine phosphoribosyltransferase-deficient fibroblasts or lymphoblasts derived from individuals with the Lesch-Nyhan syndrome. Clonal lines of hypoxanthine phosphoribosyltransferase-deficient neuroblastoma cells may therefore be of use in elucidating the mechanisms by which the enzyme defect leads to the neurologic dysfunction seen in children with this disease.
Collapse
|