Dietary cholesterol utilization by the housefly, Musca domestica

Dwivedy, A.K.

doi:10.1016/0020-1790(85)90054-x

Cited by 6 publications

(5 citation statements)

References 14 publications

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“…Cholesterol is an essential nutrient to insects due to the lack of de novo cholesterol biosynthesis . The ability of AeSCP-2 to bind β-sitosterol is of interest because A. aegypti larvae effectively convert β-sitosterol to cholesterol , whereas conversion of phytosterols to cholesterol most likely takes place in the insect midgut − . Furthermore, the level of AeSCP-2 expression is high in the midgut during the larval feeding stage .…”

Section: Discussionmentioning

confidence: 99%

Effects of Mutations in Aedes aegypti Sterol Carrier Protein-2 on the Biological Function of the Protein

2010

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Sterol carrier protein-2 (SCP-2) is a non-specific intracellular lipid carrier protein. However, the molecular mechanism of ligand selectivity and the in vivo function of SCP-2 remain unclear. In this study, we used site directed mutagenesis to investigate ligand selectivity and in vivo function of the yellow fever mosquito sterol carrier protein-2 protein (AeSCP-2). Mutations to amino acids in AeSCP-2 known to interact with bound ligand also decreased NBD-cholesterol binding. Substitution of amino acids in the ligand cavity changed the ligand specificity of mutant AeSCP-2. Over-expressing AeSCP-2 wild-type in the Aedes aegypti cultured Aag-2 cells resulted in an increase in incorporation of [3H]cholesterol. However, over-expressing mutants that were deleterious to the binding of NBD-cholesterol in AeSCP-2 showed a loss in the ability to enhance uptake of [3H] cholesterol in cultured cells. Interestingly, when [3H]palmitic acid was used as the substrate for incorporation in vivo, there was no change in the levels of incorporation with over-expression of wild-type protein or mutated AeSCP-2s. The in vivo data suggest that AeSCP-2 is involved in sterol uptake, but not fatty acid uptake. This is the first report that the ability of cholesterol binding may directly correlate to AeSCP-2’s in vivo function in aiding the uptake of cholesterol.

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Section: Discussionmentioning

confidence: 99%

Effects of Mutations in Aedes aegypti Sterol Carrier Protein-2 on the Biological Function of the Protein

2010

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“…In contrast, insects do not synthesize cholesterol de novo owing to the lack of three key enzymes in the cholesterol synthesis pathway (Zdobnov et al ., 2002). Insects have the tendency to accumulate cholesterol in the body during feeding stages (Beydon & Lafont, 1987), they have a very low rate of cholesterol catabolism (Jouni et al ., 2002) and increasing dietary cholesterol results in increased excretion of cholesterol (Dwivedy, 1985; Langley et al ., 1987). Perhaps, there is little demand on transporting cholesterol into peroxisomes for oxidation‐mediated degradation in insects.…”

Section: Discussionmentioning

confidence: 99%

Expression of a sterol carrier protein‐x gene in the Yellow fever mosquito, Aedes aegypti

Lan

Wessely

2004

Insect Molecular Biology

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The sterol carrier protein-x (SCP-x), a peroxisomal thiolase/nonspecific lipid binding protein, was characterized in the yellow fever mosquito, Aedes aegypti. The Aedes aegypti SCP-x (AeSCP-x) has 83% and 75% similarities to Drosophila and mammalian SCP-x, respectively. However, the AeSCP-x gene did not produce multiple transcripts, which is characteristic of the vertebrate SCP-x gene. Levels of AeSCP-x transcription were higher in larvae and pupae. Gut tissue showed the highest level of AeSCP-x mRNA in larvae. In adults, low levels of AeSCP-x transcription were detected in both sexes. Polyclonal antibodies against the sterol carrier protein-2 (SCP-2) domain of AeSCP-x detected two proteins of 62 kDa and 13 kDa. The results indicate that AeSCP-x is proteolytically cleaved after translation to produce a smaller protein that contains only the SCP-2 domain, which is similar to post-translational modification of the vertebrate's SCP-x to produce multiple products.

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“…In a typical eukaryotic cell, cholesterol constitutes 14% of the cytoplasmic membrane (Jain, 1988), and in neurones amounts to 40% of the synaptic membrane (Breckenridge et al ., 1973). Analysis of complete genomes of Drosophila melanogaster and Anopheles gambiae have shown that these species lack key enzymes in the cholesterol biosynthesis pathway (Zdobnov et al ., 2002), thus depend on dietary cholesterol or sterols to survive (Clayton, 1964; Noda et al ., 1979; Ritter & Nes, 1981; Dwivedy & Shukla, 1982; Nes et al ., 1997).…”

Section: Introductionmentioning

confidence: 99%

Functional analysis of AeSCP‐2 using gene expression knockdown in the yellow fever mosquito, Aedes aegypti

Blitzer

Vyazunova

Lan

2005

Insect Molecular Biology

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The effect of gene expression knockdown was used to study the function of the sterol carrier protein-2 (AeSCP-2) in the yellow fever mosquito, Aedes aegypti. Injection of small double stranded AeSCP-2 RNAs into mosquito larvae resulted in the knockdown of gene products. The lack of AeSCP-2 in larvae coincided with a reduction in accumulated cholesterol in pupae, supporting the hypothesis that AeSCP-2 may be involved in cholesterol uptake in mosquito larvae. Knockdown of AeSCP-2 caused a high mortality rate in developing adult and reduced egg viability. Results from this study indicate that AeSCP-2 is important for adult development and for the viability of the eggs.

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Dietary cholesterol utilization by the housefly, Musca domestica

Cited by 6 publications

References 14 publications

Effects of Mutations in Aedes aegypti Sterol Carrier Protein-2 on the Biological Function of the Protein

Effects of Mutations in Aedes aegypti Sterol Carrier Protein-2 on the Biological Function of the Protein

Expression of a sterol carrier protein‐x gene in the Yellow fever mosquito, Aedes aegypti

Functional analysis of AeSCP‐2 using gene expression knockdown in the yellow fever mosquito, Aedes aegypti

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