Effect Of Compactin Research Articles

Effect of Compactin on the Mycotoxin Production and Expression of Related Biosynthetic and Regulatory Genes in Toxigenic Fusarium culmorum

Zearalenone (ZEN) and deoxynivalenol (DON) are mycotoxins produced by various species of Fusarium fungi. They contaminate agricultural products and negatively influence human and animal health, thus representing a serious problem of the agricultural industry. Earlier we showed that compactin, a secondary metabolite of Penicillium citrinum, is able to completely suppress the aflatoxin B1 biosynthesis by Aspergillus flavus. Using the F. culmorum strain FC-19 able to produce DON and ZEN, we demonstrated that compactin also significantly suppressed both DON (99.3%) and ZEN (100%) biosynthesis. The possible mechanisms of this suppression were elucidated by qPCR-based analysis of expression levels of 48 biosynthetic and regulatory genes. Expression of eight of 13 TRI genes, including TRI4, TRI5, and TRI101, was completely suppressed. A significant down-regulation was revealed for the TRI10, TRI9, and TRI14 genes. TRI15 was the only up-regulated gene from the TRI cluster. In the case of the ZEN cluster, almost complete suppression was observed for PKS4, PKS13, and ZEB1 genes, and the balance between two ZEB2 isoforms was altered. Among regulatory genes, an increased expression of GPA1 and GPA2 genes encoding α- and β-subunits of a G-protein was shown, whereas eight genes were down-regulated. The obtained results suggest that the main pathway for a compactin-related inhibition of the DON and ZEN biosynthesis affects the transcription of genes involved in the G-protein-cAMP-PKA signaling pathway. The revealed gene expression data may provide a better understanding of genetic mechanisms underlying mycotoxin production and its regulation.

Stimulation of Protein Kinase C Activity by Compactin in Vascular Smooth Muscle Cells

The effect of compactin (a lovastatin analogue) on vascular smooth muscle cells was studied at the level of cell proliferation and protein kinase C. It was observed: a) an inhibition of cell proliferation by compactin at a micromolar range, which was prevented by simultaneous addition of mevalonate; b) a stimulation of DNA synthesis with a shift in the cell cycle kinetics, either in the presence or absence of fetal calf serum and c) an increase in protein kinase C activity in compactin-treated cells in the G1 phase of the cycle. This increase was similar to the one elicited by calyculin A, an inhibitor of protein phosphatases of type PP-1 and PP-2A. It is suggested that compactin behaves as a PP-1/PP-2A protein phosphatase inhibitor, inhibiting proliferation.

Effects of compactin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on the growth of alfalfa (Medicago sativa) seedlings and the rhizogenesis of pepper (Capsicum annuum) explants

The effects of compactin, a specific inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on the growth of alfalfa seedlings in vivo and the rhizogenesis of pepper explants in vitro were investigated. Compactin added to the agar medium inhibited the elongation of roots and hypocotyls of etiolated alfalfa seedlings. The growth inhibition was accompanied by strict inhibition of sterol synthesis. Addition of mevalonic acid, the direct product of 3-hydroxy-3-methylglutaryl coenzyme A reductase, together with compactin relieved the growth inhibition. The sterol level in the seedlings was also protected against the lowering effect of compactin. Similarly, the rhizogenetic process of cultured explants of pepper was inhibited by compactin and relieved by mevalonic acid. Several isoprenoid end products were tested in combination with compactin to determine which compounds, if any, might be limiting for growth. Exogenously supplied isoprenoids failed to relieve the growth inhibition of seedlings. In contrast, they partly relieved the growth inhibition of explants, suggesting their important role in plant growth. During the course of these experiments, it was also found that brassinolide caused remarkable growth inhibition and twisting of alfalfa seedlings.

A mevalonate requirement for maintenance of fatty acid and protein synthesis during hormonally stimulated development of mammary gland in vitro.

The effect of compactin on hormonally induced lipogenesis and protein synthesis was studied in vitro in explants of mammary gland from mid-pregnant rabbits. Compactin blocks mevalonate synthesis by the specific inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase, and in this system, culture with 10 microM compactin for 24, 48, and 72 h inhibited incorporation of [1-14C]acetate (but not [2-14C]mevalonate) into sterol by 98, 95, and 86%, respectively. Removal of compactin prior to assay rapidly reversed this effect and was associated with increased tissue 3-hydroxy-3-methylglutaryl-CoA reductase activity. Fatty acid synthesis (measured by incorporation of [1-14C]acetate or [4,5-3H]leucine) and protein synthesis (measured by incorporation of [4,5-3H]leucine) were both inhibited by around 50% after culture with compactin. This inhibition was not rapidly reversed by removal of compactin prior to assay, but it was prevented by inclusion of 1 mM mevalonolactone in the culture medium. After removal of compactin and continued culture in its absence for 24 h with hormones, the normal tissue capacity for fatty acid and protein synthesis was restored, indicating no permanent cell damage. The results suggest a specific requirement for mevalonate (or derived products) for the hormonal maintenance of the increased fatty acid and protein synthesis characteristic of the development of the mammary gland.

Relation of cholesterol to astrocytic differentiation in C-6 glial cells.

The relation of cellular cholesterol content to a biochemical expression of astrocytic differentiation was investigated in cultured C-6 glial cells. The astrocytic marker, glutamine synthetase, was studied. Cellular sterol content was perturbed with compactin, a specific inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase and, thereby, cholesterol biosynthesis. Depletion of cellular sterol resulted in 72 h in a more than twofold increase in glutamine synthetase activity. Production of various degrees of sterol depletion with different concentrations of compactin demonstrated a striking inverse relationship between glutamine synthetase activity and the cellular sterol/phospholipid molar ratio. That the effect of compactin, in fact, is mediated by depletion of sterol was shown further by prevention of the compactin-induced increase in synthetase activity by simultaneous addition of exogenous cholesterol. Moreover, addition of cholesterol alone to the culture medium led to both a decrease in glutamine synthetase activity and an increase in the sterol/phospholipid molar ratio. The possibility that the compactin-induced increase in glutamine synthetase activity is caused by an increase in synthesis of the enzyme was suggested by prevention of the increase by cycloheximide. The data suggest that astrocytic differentiation is stimulated by a decrease in cellular sterol content. When considered with our previous observation that oligodendroglial differentiation is inhibited by such a decrease, the findings suggest that cellular sterol content is a critical determinant of the direction of glial differentiation, i.e., whether along astrocytic or oligodendroglial lines.

Sterol biosynthesis: effect of compactin and its derivatives.

Conference Article| December 01 1983 Sterol biosynthesis: Effect of compactin and its derivatives ROBIN FEARS ROBIN FEARS 1Beecham Pharmaceuticals Research Division, Great Burgh, Epsom, Surrey KT18 5XQ, U.K. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1983) 11 (6): 642–644. https://doi.org/10.1042/bst0110642 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation ROBIN FEARS; Sterol biosynthesis: Effect of compactin and its derivatives. Biochem Soc Trans 1 December 1983; 11 (6): 642–644. doi: https://doi.org/10.1042/bst0110642 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search Keywords: HDL, high-density lipoprotein, LDL, low density lipoprotein, VLDL, very-low-density lipoprotein, HMG-CoA. β-hydroxy-β-methylglutaryl-CoA This content is only available as a PDF. © 1983 Biochemical Society1983 Article PDF first page preview Close Modal You do not currently have access to this content.

Relation of cholesterol to oligodendroglial differentiation in C-6 glial cells.

The relation of cellular cholesterol content of a biochemical expression of oligodendroglial differentiation was studied in cultured C-6 glial cells. Induction of the oligodendroglial marker enzyme 2':3'-cyclic nucleotide 3'-phosphohydrolase (CNP) was determined after alteration of the sterol content of cellular membranes by exposure to compactin, a specific inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase and cholesterol synthesis. The sterol content and, as a consequence, the sterol/phospholipid molar ratio of C-6 glial cells were decreased by treating the cells, in 10% lipoprotein-poor serum, with various concentrations of compactin for 24 h. The degrees of sterol depletion thus produced were maintained for 48 h after removal of the compactin if the cells were maintained in serum-free medium, the culture conditions necessary for induction of CNF in untreated cells. Forty-eight hours after removal of serum, no induction of CNP occurred in cells previously treated with 0.5 micrograms/ml of compactin, whereas untreated cells exhibited a three- to fourfold increase in CNP activity. Intermediate degree of sterol depletion resulted in intermediate degrees of inhibition of the CNP induction. Moreover, the morphological expressions of glial differentiation observed in the untreated cells did not occur in the sterol-depleted cells. That the effect of compactin on the induction of CNP relates to depletion of sterol was indicated by the finding that when low-density lipoprotein was added to the compactin-treated cells, the induction of CNP, the morphological expressions of differentiation, and the sterol/phospholipid molar ratios were preserved. The degree of sterol depletion that totally prevented the induction of CNP had no effect on (Na+ R K+)-activated ATPase activity, total protein synthesis, and cell viability. The data define a critical role for sterol in oligodendroglial differentiation in this model system.

Effect of compactin on the incorporation of mevalonolactone into gibberellic acid by Gibberella fujikuroi

Abstract In Gibberella fujikuroi , strain GF-1a, the effect of the sodium salt of compactin on the incorporation of both radiolabelled acetate and mevalonate into gibberellic acid has been investigated. In each case, a concentration of 40 mg/1. caused a significant reduction in the incorporation.

Regulation of 3-hydroxy-3-methylglutaryl-CoA reductase by endogenous sterol synthesis in cultured intestinal mucosa

In vitro regulation of the key enzyme of cholesterol synthesis, 3-hydroxy-3-methylglutaryl-CoA reductase (EC 1.1.1.34) by compactin, a competitive inhibitor of the enzyme, and mevalonate was studied in rabbit ileum organ culture. Addition of compactin suppressed ileum homogenate reductase activity by over 80% at concentrations up to 0.5 μg/ml. In contrast, compactin at the same concentrations added to the culture medium induced reductase activity up to 240% of controls. This increase was blocked by cycloheximide and mevalonolactone at 10 mM, but not by mevalonate (salt form) and cholesterol. Similarly, in contrast to ionized mevalonate, mevalonolactone significantly suppressed reductase activity of cultured intestine at 1 and 10 mM by 23 and 62%, respectively. A minor effect was also observed with preformed enzyme in fresh mucosal homogenate. When endogenous cholesterol synthesis was blocked by compactin, mucosal alkaline phosphatase activity decreased progressively, whereas medium activity from desquamated cells did not change. This distribution of the villous cell marker enzyme is characteristic of a decrease in crypt cell renewal and/or villous cell differentiation. This effect of compactin was also reversible with mevalonolactone. The reductase enzyme induced by compactin was probably latent intracellularly, since tissue cholesterol contents dropped sharply after blockade of endogenous sterol synthesis.

The effect of compactin, a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme—A reductase activity, on cholesterogenesis and serum cholesterol levels in rats and chicks

Compactin, [7-(1,2,6,7,8,8a-hexahydro-2-methyl-8-(2-methylbutyryloxy) naphthyl)-3-hydroxyheptan-5-olide], a potent competitive inhibitor of the rate-determining step in cholesterol biosynthesis, was used to study the influence of changes in cholesterogenesis on serum cholesterol levels. Up to 3 h after a single oral dose (20 or 50 mg/kg) or after the last of a series of daily oral doses (50 mg/kg for 7 or 28 days) to young, male normolipid-aemic rats, compactin consistently inhibited cholesterogenesis measured using 3H 2O in liver, ileum and other extrahepatic tissues without affecting fatty acid synthesis. Compactin did not reduce serum or tissue cholesterol nor affect the serum concentration of other lipids nor the ratio between lipoprotein classes. A diurnal variation in the effect of compactin on cholesterogenesis was observed. For example, by 12–20 h after dosing, cholesterogenesis at all sites was increased above the comparable control value, indicating the induction of enzyme synthesis and overall there was little effect on the mass of cholesterol synthesized per day. Similar results were obtained using male chicks. Inhibition of cholesterogenesis by compactin was also observed in cholestyramine-treated rats, in which cholesterol turnover was markedly increased, and even in cholesterol-fed rats, in which cholesterogenesis already was repressed. In neither case, however, was inhibition of cholesterogenesis accompanied by a hypocholesterolaemic effect. It is concluded that a more persistent suppression of cholesterogenesis, than that observed with compactin in the rat, may be required in order to affect serum cholesterol concentrations.