Understanding the Relationship Between Ecdysone Signaling and the Lipin Protein in Drosophila melanogaster
Date
2023-07-06
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Abstract
Drosophila melanogaster, the common fruit fly, undergoes four major
stages of development: embryonic stage, larval stage, pupal stage, and adult stage.
During the larval stage, individuals increase in size and consume nutrients, which
are then stored in the cells of the fat body. When the larva reaches critical weight,
the formation of the pupal case or pupariation occurs over four days and
undergoes a transformation from its larval form to its adult form. During these
four days, the pupa will not consume any external nutrients and is reliant on the
nutrients stored in the cells of the fat body as a result. The pupal stage is an
energetically expensive process.
In Drosophila, there is a single lipin gene orthologue known as dLipin.
Lipin is a protein that is encoded by the lipin gene. Lipin is considered essential
for normal adipose tissue development and triacylglycerol (TAG) storage. dLipin
is linked to energy metabolism and is considered to be crucial under nutrient
deprivation conditions. dLipin also plays a role in insulin sensitivity in the larval
fat body (Lehmann, 2018). Ecdysone is a steroid hormone that acts through a
receptor to regulate the transcription of specific target genes. This steroid
hormone is the central regulator of developmental transitions in Drosophila and
leads to pupariation at the beginning of metamorphosis. I hypothesize that
ecdysone signaling activates the transcription of the dLipin gene during
metamorphosis.
To test this hypothesis, I am using the wild-type genotype as a control, and
Cg-Gal4; UAS-EcR-DN flies as an ecdysone-signaling-deficient experimental
genotype. Results of the Real-Time Quantitative Polymerase Chain Reaction
(qRT-PCR) indicate the opposite of the hypothesis and that ecdysone signaling
instead inhibits the transcription of the dLipin gene. Ecdysone deficient
Drosophila resulted in up-regulation of dLipin compared to the wild-type
Drosophila. Studying lipin in the Drosophila model will help lead to an
understanding of the basic function of lipin in metazoans and lipin’s role in fat
cell function and energy metabolism (Schmitt, 2015).
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Keywords
Lipin, Drosophila melanogaster, dLipin, Metamorphosis, Ecdysone Signaling, Nutrients