De novo synthesis of fructo-oligosaccharides in leaf disks of certain Asteraceae

1972 ◽  
Vol 50 (2) ◽  
pp. 295-303 ◽  
Author(s):  
K. R. Chandorkar ◽  
F. W. Collins
Keyword(s):  
Chain Length ◽  
De Novo ◽  
Close Correlation ◽  
Acid Synthesis ◽  
Degree Of Polymerization ◽  
De Novo Synthesis ◽  
The Relationship ◽  
Leaf Disks

Incubation of leaf disks of certain genera of Asteraceae on phosphate-buffered, 5% sugar solutions resulted in the de novo synthesis of a homologous series of inulin-type fructosans. Fructo-oligosaccharides of degree of polymerization 3 to 21 or 22 were present in dandelion, chicory, lettuce, hawkweed, and sow thistle leaf disks after 72 h, but not in dahlia or sunflower. Synthesis occurred with media containing either fructose, glucose, or sucrose, but not with mannose or galactose. Fructosan formation began after about 36 h and continued with the sequential synthesis of homologs of increasing chain length. After 72 h, the relationship between the amount of polymer synthesized and the chain length appeared to be logarithmically biphasic, consisting of two series of exponentially decreasing values. Incubation for 120 h however, resulted in a distribution more closely resembling that found naturally in fructosan storing tissues. 14C-tracer studies showed that both the endogenous and exogenous carbohydrate sources contribute to fructosan synthesis. Fructo-oligosaccharide formation was blocked by cycloheximide, puromycin, and actinomycin D but not chloramphenicol, indicating that cytoplasmic protein and nucleic acid synthesis was required. Analysis of fructosan formation during incubation suggests a close correlation between transfructosylation mechanisms observed in vitro and the de novo synthesis of fructosans in vivo.

scholarly journals Deoxyribonucleic acid synthesis in mammalian nuclei. Incorporation of deoxyribonucleotides and chain-terminating nucleotide analogues

1971 ◽  
Vol 121 (5) ◽  
pp. 803-809 ◽  
Author(s):  
M. A. Waqar ◽  
L. A. Burgoyne ◽  
M. R. Atkinson
Keyword(s):  
Dna Synthesis ◽  
Deoxyribonucleic Acid ◽  
Acid Synthesis ◽  
Deoxyribonucleic Acid Synthesis ◽  
Dna Chain ◽  
Relationship Of ◽  
The Relationship ◽  
Neighbour Analysis

The properties of a nuclear preparation from rat liver and thymus are described. (1) Nearest-neighbour analysis after incorporation of 32P-labelled nucleotide residues from dATP, dCTP, dGTP, dTTP and arabinofuranosyl analogues of CTP and ATP shows template-dependent DNA synthesis. (2) Where primer termini are limiting, incorporation of arabinofuranosyl analogues of AMP and CMP residues proceeds to a limit indicating that both of these analogues are DNA chain terminators. (3) No large differences have been found between the priming potentialities or the intrinsic DNA polymerase activities of nuclei from resting or regenerating liver and the relationship of this DNA synthesis in vitro to DNA replication or repair in vivo is briefly discussed.

scholarly journals USP22-dependent accumulation of lipidomes drives hepatocellular carcinoma progression by stabilizing PPARγ

2020 ◽  
Author(s):  
Zhen Ning ◽  
Xin Guo ◽  
Xiaolong Liu ◽  
Chang Lu ◽  
Aman Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Fatty Acid ◽  
Molecular Mechanism ◽  
Fatty Acid Synthesis ◽  
De Novo ◽  
Acid Synthesis ◽  
Specific Protease ◽  
Pparγ Expression

Abstract Elevated de novo lipogenesis (DNL) is considered to be a crucial factor in hepatocellular carcinoma (HCC) development. However, the molecular mechanism for its occurrence in HCC is still unclear. Herein, we identified ubiquitin-specific protease 22 (USP22) as a key regulator for de novo fatty acid synthesis, which directly interacts with, deubiquitinates and stabilizes PPARγ through K48-linked deubiquitination, and in turn, this stabilization increases ACC and ACLY transcription. In addition, we found that USP22 promoted the de novo synthesis of fatty acid labeling from glucose tracers. USP22-dysregulated de novo fatty acid synthesis contributes to HCC progression, but USP22 was functionality suppressed by inhibiting the expression of PPARγ, ACLY, or ACC in in vitro cell proliferation and in vivo tumorigenesis experiments. In HCC, USP22 expression positively correlates with PPARγ expression, and simultaneously, high expression of USP22 and PPARγ or USP22, ACC and ACLY is associated with a poor prognosis. Taken together, we identified a previously undescribed USP22-regulated lipogenesis molecular mechanism that involves the PPARγ-ACLY/ACC axis in HCC tumorigenesis and provide a rationale for therapeutic targeting of lipogenesis via USP22 inhibition.

Isotopomer spectral analysis of intermediates of cholesterol synthesis in human subjects and hepatic cells

2002 ◽  
Vol 282 (6) ◽  
pp. E1222-E1230 ◽  
Author(s):  
B. Lindenthal ◽  
T. A. Aldaghlas ◽  
A. L. Holleran ◽  
T. Sudhop ◽  
H. K. Berthold ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Liver Cell ◽  
Cholesterol Synthesis ◽  
De Novo ◽  
Human Subjects ◽  
Cell Models ◽  
Turnover Rates ◽  
De Novo Synthesis

Steroid intermediates of the cholesterol synthesis pathway are characterized by rapid turnover rates relative to cholesterol due to their small pool size. Because the small pools will label rapidly, these intermediates may provide valuable information about the incorporation of isotopes in de novo synthesis of cholesterol and related compounds. The labeling of cholesterol synthesis intermediates from [1-13C]acetate was investigated in human subjects and in liver cell models by means of isotopomer spectral analysis (ISA). In human subjects, infusing [1-13C]acetate into the duodenum for 12 h demonstrated that ∼50% of the plasma lathosterol pool was derived from de novo synthesis during this interval. The lipogenic acetyl-CoA precursor pool enrichment reached a constant value within 3 h of the start of the infusion. In vitro studies indicated that liver cell models decrease de novo lathosterol synthesis when cholesterol synthesis is inhibited by statins or cholesterol-containing serum. We propose a new calculation to increase the accuracy and precision of cholesterol synthesis estimates in vivo combining the ISA of lathosterol and cholesterol.

scholarly journals The contrary intracellular and extracellular functions of PEDF in HCC development

2019 ◽  
Vol 10 (10) ◽  
Author(s):  
Cen Li ◽  
Zhijian Huang ◽  
Liuqing Zhu ◽  
Xianhuan Yu ◽  
Tianxiao Gao ◽  
...  
Keyword(s):  
De Novo ◽  
Pigment Epithelium ◽  
Animal Experiments ◽  
Underlying Mechanism ◽  
Acid Synthesis ◽  
Angiogenic Inhibitor ◽  
Growth Activation ◽  
Ubiquitin Proteasome

Abstract Pigment epithelium-derived factor (PEDF), a classic angiogenic inhibitor, has been reported to function as a tumor suppression protein and to downregulate in many types of solid tumors. However, the expression level of PEDF and its role in hepatocellular carcinoma (HCC) are contradictory. The present study investigates the expression and different activities of secreted and intracellular PEDF during HCC development, as well as the underlying mechanism of PEDF on HCC lipid disorders. We found that PEDF had no association with patients’ prognosis, although PEDF was highly expressed and inhibited angiogenesis in HCC tumor tissues. The animal experiments indicated that full-length PEDF exhibited equalizing effects on tumor growth activation and tumor angiogenesis inhibition in the late stage of HCC progression. Importantly, the pro-tumor activity was mediated by the intracellular PEDF, which causes accumulation of free fatty acids (FFAs) in vivo and in vitro. Based on the correlation analysis of PEDF and lipid metabolic indexes in human HCC tissues, we demonstrated that the intracellular PEDF led to the accumulation of FFA and eventually promoted HCC cell growth by inhibiting the activation of AMPK via ubiquitin–proteasome-mediated degradation, which causes increased de novo fatty acid synthesis and decreased FFA oxidation. Our findings revealed why elevated PEDF did not improve the patients’ prognosis as the offsetting intracellular and extracellular activities. This study will lead to a comprehensive understanding of the diverse role of PEDF in HCC and provide a new selective strategy by supplement of extracellular PEDF and downregulation of intracellular PEDF for the prevention and treatment of liver cancer.

scholarly journals The de novo synthesis of numerous proteins is decreased during vitamin D3 deficiency and is gradually restored by 1, 25-dihydroxyvitamin D3 repletion in the islets of langerhans of rats

1999 ◽  
Vol 162 (1) ◽  
pp. 101-109 ◽  
Author(s):  
PM Bourlon ◽  
A Faure-Dussert ◽  
B Billaudel
Keyword(s):  
Molecular Weight ◽  
Vitamin D3 ◽  
Protein Production ◽  
De Novo ◽  
De Novo Synthesis ◽  
Glucose Stimulation ◽  
Dihydroxyvitamin D3 ◽  
Vitamin D3 Deficiency

Since both the release and de novo biosynthesis of insulin are severely decreased by vitamin D3 deficiency and improved by 1, 25-dihydroxyvitamin D3 (1,25(OH)2D3) repletion following a 6-h delay in the rat, the present experiments investigated the effects of vitamin D3 deficiency on the biosynthesis of heavier molecular weight proteins using electrophoretic separation. Gel protein staining by Coomassie blue showed very different profiles for islets protein production from 4-week vitamin D3-deficient rats compared with normal islets. The pattern was characterised by a decrease in high molecular weight proteins, concomitantly accompanied by an increase in low molecular weight proteins. This tendency was partially reversed in vivo by 1,25(OH)2D3 repletion treatment for 7 days and was evident after only 16 h of treatment. In parallel with these in vivo observations, which represent a static index of islets protein production, a kinetic study was performed in vitro by a double-labelling method allowing us to measure the de novo synthesis of proteins in islets during a strong 16.7 mM glucose stimulation. Comparison of 3H and 14C labelled samples was achieved via coelectrophoresis to avoid experimental artefacts. The study of the ratio of d.p.m. 3H/d.p.m. 14C for each molecular weight protein in islets stimulated by 16.7 mM glucose (versus basal 4.2 mM glucose) showed an increase in the height of certain peaks: 150, 130 and 8.5 kDa. Under the same conditions, islets from 4-week vitamin D3-deficient rats (versus normal islets) presented a large deficit of numerous newly synthesised proteins and particularly those implicated in the response to glucose stimulation. In vitro repletion of 1,25(OH)2D3 tended to reverse, at least in part, the deleterious effect of vitamin D3 deficiency on the de novo protein synthesis of islets but these effects were gradual. Indeed, there was no detectable effect at 2 h incubation, but 1,25(OH)2D3 increased the 60 to 65 kDa, 55 kDa, and 9 to 8 kDa molecular mass proteins at 4 h, and increased the level of most newly synthesised proteins at 6 h. These data support the hypothesis of a beneficial genomic influence of 1,25(OH)2D3 that occurs progressively within the islets of Langerhans and which may prepare the beta cells for an enhanced response to glucose stimulation.

The mechanism of de novo synthesis of fructooligosaccharides in leaf disks of certain Asteraceae. III.

1974 ◽  
Vol 52 (1) ◽  
pp. 181-188 ◽  
Author(s):  
K. R. Chandorkar ◽  
F. W. Collins
Keyword(s):  
De Novo ◽  
Specific Activity ◽  
Jerusalem Artichoke ◽  
De Novo Synthesis ◽  
Jerusalem Artichoke Tuber ◽  
Exogenous Substrate ◽  
Endogenous Substrate ◽  
Leaf Disks ◽  
Tracer Experiments

14C-tracer experiments revealed that both endogenous and exogenous substrate was incorporated in the fructosans synthesized in leaf disks during incubation on phosphate-buffered sugar media. At least some of the endogenous substrate was derived from a source which was insoluble in 80% ethanol at the start of the incubation period. Endogenous and exogenous substrates were distributed in the fructosans in a pattern which was qualitatively similar regardless of the type of sugar supplied exogenously. A complex relationship was exhibited between the specific activity of various fructosan oligomers, expressed on a gram basis, and their chain length. However, expressed on a molar basis, the specific activity of the fructosyl tail portion of each homolog appeared to be linearly related to the number of hexosyl residues that it contained. Such a relationship suggests that enzymes similar to the Jerusalem artichoke tuber transfructosylases are present in leaf disk tissue after 72 h incubation and indeed may function in the de novo synthesis of fructosans in vivo.

scholarly journals Cyclooxygenases in Rat Leydig Cells: Effects of Luteinizing Hormone and Aging

Endocrinology ◽  
2007 ◽  
Vol 148 (2) ◽  
pp. 735-742 ◽  
Author(s):  
Haolin Chen ◽  
Lindi Luo ◽  
June Liu ◽  
Barry R. Zirkin
Keyword(s):  
Leydig Cell ◽  
Leydig Cells ◽  
Close Correlation ◽  
Dibutyryl Camp ◽  
Protein Levels ◽  
Testosterone Production ◽  
Age Related ◽  
The Relationship

Previous studies suggested that increased Leydig cell cyclooxygenase (COX)2 expression may be involved in the reduced testosterone production that characterizes aged Leydig cells. Our objective herein was to further elucidate the relationships among LH stimulation, Leydig cell COX2 and COX1 expression, aging, and testosterone production. Incubation of Leydig cells from young or aged rats with LH or dibutyryl cAMP resulted in increases in both intracellular COX2 protein expression and testosterone production. COX1 expression did not respond to LH or dibutyryl cAMP. Incubation of adult cells with a protein kinase A inhibitor suppressed the stimulatory effects of LH on COX2 and testosterone production. Short-term incubation of Leydig cells with TGF-α or IL-1β also increased COX2 protein levels; IGF-I had no effect. In vivo, LH also was found to stimulate both COX2 and testosterone, but not COX1. As reported previously, COX2 expression was greater in old than in young cells, and old Leydig cells responded to inhibition of COX2 in vitro with increased testosterone production. However, the effects of the COX2 inhibitors were not restricted to old cells; young Leydig cells also responded to COX2 inhibition with increased testosterone production. This and the observation that the incubation of young or old cells with LH resulted in increased COX2 and testosterone production in both cases suggests that the relationship between COX2 and testosterone production is not unique to aged Leydig cells. Moreover, the close correlation between increases in COX2 and testosterone in LH-stimulated young and aged Leydig cells is difficult to reconcile with the contention that the increased expression of COX2 in aged cells is responsible for age-related suppression of Leydig cell testosterone production.

scholarly journals CcpC-Dependent Regulation of Citrate Synthase Gene Expression in Listeria monocytogenes

2008 ◽  
Vol 191 (3) ◽  
pp. 862-872 ◽  
Author(s):  
Meghna Mittal ◽  
Silvia Picossi ◽  
Abraham L. Sonenshein
Keyword(s):  
Listeria Monocytogenes ◽  
Citrate Synthase ◽  
De Novo ◽  
Krebs Cycle ◽  
Proximal Promoter ◽  
De Novo Synthesis ◽  
Distal Promoter ◽  
Rate Limiting

ABSTRACT Citrate synthase, the first and rate-limiting enzyme of the tricarboxylic acid branch of the Krebs cycle, was shown to be required for de novo synthesis of glutamate and glutamine in Listeria monocytogenes. The citrate synthase (citZ) gene was found to be part of a complex operon with the upstream genes lmo1569 and lmo1568. The downstream isocitrate dehydrogenase (citC) gene appears to be part of the same operon as well. Two promoters were shown to drive citZ expression, a distal promoter located upstream of lmo1569 and a proximal promoter located upstream of the lmo1568 gene. Transcription of citZ from both promoters was regulated by CcpC by interaction with a single site; assays of transcription in vivo and assays of CcpC binding in vitro revealed that CcpC interacts with and represses the proximal promoter that drives expression of the lmo1568, citZ, and citC genes and, by binding to the same site, prevents read-through transcription from the distal, lmo1569 promoter. Expression of the lmo1568 operon was not affected by the carbon source but was repressed during growth in complex medium by addition of glutamine.

Regulatory Factors Associated with Synthesis of the Osmolyte Glycine Betaine in the Halophilic MethanoarchaeonMethanohalophilus portucalensis

1999 ◽  
Vol 65 (2) ◽  
pp. 828-833 ◽  
Author(s):  
Mei-Chin Lai ◽  
Daw-Renn Yang ◽  
Ming-Jen Chuang
Keyword(s):  
Glycine Betaine ◽  
De Novo ◽  
Compatible Solutes ◽  
In Vitro Assays ◽  
Intracellular Accumulation ◽  
De Novo Synthesis ◽  
Factors Associated ◽  
High Level

ABSTRACT The halophilic methanoarchaeon Methanohalophilus portucalensis can synthesize de novo and accumulate β-glutamine, N ɛ-acetyl-β-lysine, and glycine betaine (betaine) as compatible solutes (osmolytes) when grown at elevated salt concentrations. Both in vivo and in vitro betaine formation assays in this study confirmed previous nuclear magnetic resonance 13C-labelling studies showing that the de novo synthesis of betaine proceeded from glycine, sarcosine, and dimethylglycine to form betaine through threefold methylation. Exogenous sarcosine (1 mM) effectively suppressed the intracellular accumulation of betaine, and a higher level of sarcosine accumulation was accompanied by a lower level of betaine synthesis. Exogenous dimethylglycine has an effect similar to that of betaine addition, which increased the intracellular pool of betaine and suppressed the levels of N ɛ-acetyl-β-lysine and β-glutamine. Both in vivo and in vitro betaine formation assays with glycine as the substrate showed only sarcosine and betaine, but no dimethylglycine. Dimethylglycine was detected only when it was added as a substrate in in vitro assays. A high level of potassium (400 mM and above) was necessary for betaine formation in vitro. Interestingly, no methylamines were detected without the addition of KCl. Also, high levels of NaCl and LiCl (800 mM) favored sarcosine accumulation, while a lower level (400 mM) favored betaine synthesis. The above observations indicate that a high sarcosine level suppressed multiple methylation while dimethylglycine was rapidly converted to betaine. Also, high levels of potassium led to greater amounts of betaine, while lower levels of potassium led to greater amounts of sarcosine. This finding suggests that the intracellular levels of both sarcosine and potassium are associated with the regulation of betaine synthesis inM. portucalensis.

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