Sterol metabolism in the nematode<i>Caenorhabditis elegans</i>

Chitwood, David J.; Lusby, William R.; Lozano, Ruben; Thompson, Malcolm J.; Svoboda, James A.

doi:10.1007/bf02534482

Cited by 40 publications

(17 citation statements)

References 24 publications

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“…Although nat-cholesterol alone satisfies the C. elegans sterol requirement, C. elegans can transform cholesterol into other sterols, most notably 7-dehydrocholesterol (12). Consequently, a metabolite of cholesterol, even if structurally quite similar to cholesterol, may perform an unknown specific, critical function.…”

Section: Table Imentioning

confidence: 99%

Enantiospecificity of Cholesterol Function in Vivo

Crowder

Westover

Kumar

et al. 2001

Journal of Biological Chemistry

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The importance of the absolute configuration of cholesterol for its function in vivo is unknown. To directly test this question in vivo, we synthesized the enantiomer of cholesterol (ent-cholesterol) and tested its ability to substitute for natural cholesterol (nat-cholesterol) in the growth, viability, and behavior of Caenorhabditis elegans, a cholesterol auxotroph. First-generation animals grown on ent-cholesterol were viable with only mild behavioral defects. However, ent-cholesterol produced 100% lethality/arrest of their second generation progeny. Isotopically labeled ent-cholesterol incorporated into animals, indicating that its lethality was not secondary to cholesterol starvation. When mixed with nat-cholesterol, ent-cholesterol was not inert; rather, it antagonized the activity of nat-cholesterol. These results demonstrate for the first time that the absolute configuration of cholesterol, not just its physical properties, is essential for its functions in vivo.The two enantiomers of a molecule are nonsuperimposable mirror images of one another that have identical physical properties; they differ only in their absolute configuration around each chiral center and hence interact differently with chiral molecules. Sterols occur in nature as only one of the two possible enantiomers. Given this fact, enantiospecific interactions between sterols and other chiral molecules such as lipids and proteins are likely to occur and to be functionally important. Yet, surprisingly little evidence exists to support this fundamental hypothesis for cholesterol, a major structural component of cell membranes. Indeed with one exception (1), investigations with model membranes have found that sterol-lipid interactions do not affect membrane properties in an enantiospecific manner (2-8). These results suggest that although the physical properties of cholesterol are important for its membrane effects, the absolute configuration of cholesterol is not. In a broader context, whether the functions of cholesterol in vivo are enantiospecific has never been explicitly investigated.The nematode Caenorhabditis elegans requires exogenous sterols for viability. Several sterols satisfy this requirement; for example, cholesterol supports the growth, reproduction, and normal behavior of C. elegans (9 -13). Thus, C. elegans provides a good model to test the enantiospecificity of function of cholesterol in vivo. Toward this end, the non-naturally occurring enantiomer of cholesterol (ent-cholesterol) 1 was synthesized ( Fig. 1) and substituted for nat-cholesterol in cultures of C. elegans. We find that ent-cholesterol is incorporated into C. elegans but cannot perform the functions of nat-cholesterol. EXPERIMENTAL PROCEDURESMaterials ent-Cholesterol was synthesized as described (14). C. elegans were provided by the Caenorhabditis Genetics Center. Agarose was supplied by Sigma. Other reagents for the NGM culture plates and bacterial media including the natural cholesterol were supplied from Fisher Scientific. MethodsCulture Conditions-The C. eleg...

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Section: Table Imentioning

confidence: 99%

Enantiospecificity of Cholesterol Function in Vivo

Crowder

Westover

Kumar

et al. 2001

Journal of Biological Chemistry

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“…The analysis of worm sterols by GC-mass spectrometry or by TLC analysis of worms fed with radioactive cholesterol demonstrated that the bulk of exogenously added sterol remains unchanged; [8][9][10] however, C. elegans is able to carry out some modifications on them. [6,[8][9][10][11][12][13][14][15] Thus, several enzymatic transformations of cholesterol were identified and the major metabolic pathway in C. elegans was outlined.…”

Section: Introductionmentioning

confidence: 99%

“…[6,[8][9][10][11][12][13][14][15] Thus, several enzymatic transformations of cholesterol were identified and the major metabolic pathway in C. elegans was outlined. [14] In this context, two transformations should be emphasized: the dehydrogenation of cholesterol at position 7 (production of 7-dehydrocholestrol) and methylation at position 4 (production of lophenol) (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Regio‐ and Stereospecific Synthesis of Cholesterol Derivatives and Their Hormonal Activity in Caenorhabditis elegans

Schmidt¹,

Doert²,

Goutal³

et al. 2006

Eur J Org Chem

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Cholesterol is essential for the survival of the nematode Caenorhabditis elegans. Recent studies have demonstrated that cholesterol derivatives regulate two processes in the life cycle of worms: controlling molting and inducing a specialized non‐feeding larval stage. However, the chemical structure of the cholesterol‐derived signalling molecules for these or any other functions has not yet been identified. Herein, we describe the regio‐ and stereospecific synthesis of a number of cholesterol derivatives. The lithium–ammonia reduction of 4‐cholesten‐3‐one was utilized to develop a general method for the introduction of diverse functional groups at C‐4α of 5α‐cholestan‐3β‐ol. Stereoselective functionalization at C‐7 was achieved starting from 7‐ketocholesterol derivatives. 6‐Keto‐5α‐cholestan‐3β‐ol was utilized for specific functionalizations at C‐6 and C‐7. The structure–activity relationships of the different cholesterol derivatives have been investigated by feeding worms of different genetic background with these compounds. Our study is the first step in assigning the relationships of hormonal activity in C. elegans on the substitution at different positions of cholesterol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…1D), it is not known exactly when depletion first occurs because we have not yet performed a time course study measuring sterols in worms treated with Aza. Second, in an earlier report, several different sterols in C. elegans were depleted by Aza treatment; cholesterol was depleted to ϳ1% of the level typically found in C. elegans after culturing with a concentration of Aza approximately one-half that used in the present study (47). From the results from our laboratory, it was observed that a transgenic worm, called cholegans, which can produce endogenous cholesterol by converting 7-dehydrocholesterol showed a 30% increase in MLS when grown in the cholesterol depletion condition (56).…”

Section: Discussionmentioning

confidence: 42%

“…Acute Toxicity of Aza on C. elegans Development-The disturbance of sterol metabolism in C. elegans by Aza toxicity has been well documented (1,3,47,48). Our investigation addressed the biochemical and cellular mechanism underlying Aza toxicity, focusing on Aza toxicity in the second generation (F2) after initial Aza treatment of parental worms (P0).…”

Section: Resultsmentioning

confidence: 99%

A Potential Biochemical Mechanism Underlying the Influence of Sterol Deprivation Stress on Caenorhabditis elegans Longevity

Cheong

Kim

et al. 2011

Journal of Biological Chemistry

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To investigate the biochemical mechanism underlying the effect of sterol deprivation on longevity in Caenorhabditis elegans, we treated parent worms (P0) with 25-azacoprostane (Aza), which inhibits sitosterol-to-cholesterol conversion, and measured mean lifespan (MLS) in F2 worms. At 25 M (ϳEC 50 ), Aza reduced total body sterol by 82.5%, confirming sterol depletion. Aza (25 M) treatment of wild-type (N2) C. elegans grown in sitosterol (5 g/ml) reduced MLS by 35%. Similar results were obtained for the stress-related mutants daf-16(mu86) and gas-1(fc21). Unexpectedly, Aza had essentially no effect on MLS in the stress-resistant daf-2(e1370) or mitochondrial complex II mutant mev-1(kn1) strains, indicating that Aza may target both insulin/IGF-1 signaling (IIS) and mitochondrial complex II. Aza increased reactive oxygen species (ROS) levels 2.7-fold in N2 worms, but did not affect ROS production by mev-1(kn1), suggesting a direct link between Aza treatment and mitochondrial ROS production. Moreover, expression of the stress-response transcription factor SKN-1 was decreased in amphid neurons by Aza and that of DAF-28 was increased when DAF-6 was involved, contributing to lifespan reduction.Sterols are important molecules involved in membrane organization, hormone production, and signal processing. Because Caenorhabditis elegans lacks a de novo sterol biosynthesis pathway, it requires dietary cholesterol or plant sterols (e.g. sitosterol) that can be converted to cholesterol or its most abundant sterol, 7-dehydrocholesterol (1, 2) (Fig. 1A). Sterol depletion experiments have revealed that a restriction in the sterol supply caused by inadequate nutrition produces serious defects in development and reduces the longevity of C. elegans (3-7). For example, sterol starvation leads to an increase in embryonic lethality (7) and a decrease in lifespan (ϳ40%) in wild-type N2 worms (6). Most of the sterol depletion phenotype also occurs when worms are grown in the presence of sitosterol as a sterol nutrient and 25-azacoprostane (Aza), 2 an inhibitor of sterol C24-reductase and dealkylation of desmosterol during its conversion to cholesterol (8). Using proteomic approaches, our laboratory has previously shown that defects in development and growth in C. elegans caused by Aza treatment are associated with changes in the abundance of many proteins (3). The major proteins influenced by Aza treatment were the lipoproteins VIT-2 and VIT-6 and their putative receptors RME-2 and LRP-1, which were previously known to respond to sterols (3). Recently, the endogenous ligands of DAF-12 have been discovered to be 3-keto bile acid-like steroids, called ⌬ 4 -and ⌬ 7 -dafachronic acids (9). Dafachronic acids and related metabolites regulate longevity and stress resistance (9 -11). DAF-36, a Rieske-like oxygenase, and DAF-9, a cytochrome P450 enzyme, produce dafachronic acid ligands that activate the DAF-12 nuclear receptor (9). It was also reported that methyltransferase STRM-1 modifies sterol substrates for the synthesis of dafachronic acid (...

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Sterol metabolism in the nematodeCaenorhabditis elegans

Cited by 40 publications

References 24 publications

Enantiospecificity of Cholesterol Function in Vivo

Enantiospecificity of Cholesterol Function in Vivo

Regio‐ and Stereospecific Synthesis of Cholesterol Derivatives and Their Hormonal Activity in Caenorhabditis elegans

A Potential Biochemical Mechanism Underlying the Influence of Sterol Deprivation Stress on Caenorhabditis elegans Longevity

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