Genomewide Expression Profiling of Cryptolepine-Induced Toxicity in Saccharomyces cerevisiae

Abstract

We have used the budding yeast Saccharomyces cerevisiae to identify genes that may confer sensitivity in vivo to the antimalarial and cytotoxic agent cryptolepine. Five S. cerevisiae strains, with different genetic backgrounds in cell permeability and DNA damage repair mechanisms, were exposed to several concentrations of cryptolepine. Cryptolepine showed a relatively mild toxicity for wild-type strains, which was augmented by either increasing cell permeability (⌬erg6 or ISE2 strains) or disrupting DNA damage repair (⌬rad52 strains). These results are compatible with the ability of cryptolepine to intercalate into DNA and thus promote DNA lesions. The effects of low concentrations of cryptolepine (20% and 40% inhibitory concentrations [IC 20 and IC 40 ]) were analyzed by comparing the gene expression profiles of treated and untreated ⌬erg6 yeast cells. Significant changes in expression levels were observed for 349 genes (117 upregulated and 232 downregulated). General stress-related genes constituted the only recognizable functional cluster whose expression was increased upon cryptolepine treatment, making up about 20% of upregulated genes. In contrast, analysis of the characteristics of downregulated genes revealed a specific effect of cryptolepine on genes related to iron transport or acid phosphatases, as well as a significant proportion of genes related to cell wall components. The effects of cryptolepine on the transcription of iron transport-related genes were consistent with a loss of function of the iron sensor Aft1p, indicating a possible disruption of iron metabolism in S. cerevisiae. Since the interference of cryptolepine with iron metabolism is considered one of its putative antimalarial targets, this finding supports the utility of S. cerevisiae in drug-developing schemes.Cryptolepine is the main indoloquinoline alkaloid found in the roots of the climbing shrub Cryptolepis sanguinolenta (Periplocaceae). In West Africa, decoctions of the roots of C. sanguinolenta are used in traditional medicine to treat malaria as well as a variety of other infectious diseases (27). Cryptolepine ( Fig. 1) has shown in vitro antiplasmodial activity (27), but this alkaloid also has cytotoxic properties in several cell lines, and the mechanisms involved may include intercalation into DNA, as well as inhibition of topoisomerase II and DNA synthesis (4). The mode of cryptolepine intercalation into DNA is peculiar in that it occurs at nonalternating C/G sequences (12).Regardless of the binding of cryptolepine to DNA (3, 12), investigations into its molecular mechanisms of action have revealed that the antiplasmodial mode of action may be different from the cytotoxic mode of action. Cryptolepine shares with chloroquine, and related quinoline antimalarial drugs, the property of binding to heme and prevents its conversion to hemazoin (28). The drug-heme complex is considered to be toxic to the parasite.Deeper knowledge of the different targets of cryptolepine should help to elucidate the basis for the relative selectivity o...

Evaluation of Cryptolepine and Huperzine Derivatives as Lead Compounds towards New Agents for the Treatment of Human African Trypanosomiasis

“…amino-3-chloro-6,7,10,11-tetrahydro-9-methyl-7,11methanocycloocta[b]-quinoline hydrochloride) [11], the 9-allyl-substituted huprine (9), (rac-9-allyl-12amino-6,7,10,11-tetrahydro-7,11-methanocycloocta[b] quinoline hydrochloride) [12] and the 9-isopropylsubstituted huprine (10), (rac-12-amino-6,7,10,11tetrahydro-9-isopropyl-7,11-methanocycloocta[b] quinoline hydrochloride) [12] were available from previous work.…”

“…It is possible that the antiplasmodial and trypanocidal activities of 7 may share a common mechanism. Recently, a study investigating the effects of 1 on gene expression in the yeast Saccharomyces cerevisiae revealed that the expression of 349 genes was significantly affected by 1 at its IC 40 concentration (117 up-regulated and 232 down-regulated) [9]. While a general up-regulation of stress-related genes was observed, specific downregulation of genes related to iron transport and acid phosphatases also occurred and the possibility that similar effects may occur in protozoa would be worthy of exploration.…”

Microarray analysis of p-anisaldehyde-induced transcriptome of Saccharomyces cerevisiae

“…In the past few years, DNA microarray technology has been used to discover gene's functions, to understand biochemical pathways and to discover drug targets [7,8]. The yeast S. cerevisiae is a eukaryotic cell model for the study of antifungal action because it adapts easily to changes in its environment and mimics many of the properties of higher organisms.…”

The Antimalarial Drug Quinine Disrupts Tat2p-mediated Tryptophan Transport and Causes Tryptophan Starvation

“…Consequently, the yeast deletion strains have been used previously to identify genetic defects that in humans could be the basis for the sensitivities of certain individuals to antimicrobial drugs (12,20). In this study, we applied this approach to the problem of adverse reactions to a major antimalarial drug for the first time, noting that similar approaches have been exploited recently for mode of action discovery with certain other antimalarials (17,21). Our analysis led to the key finding that yeast trp mutants (which rely on an exogenous supply of Trp, like mammals) are quinine-hypersensitive, and that quinine specifically obstructs Trp acquisition by cells.…”