The Interactive Fly
Genes involved in tissue and organ development
What distinguishes ectoderm from epidermis?
Genes expressed in the amnioserosa
Dysfunction of Oskyddad causes Harlequin-type ichthyosis-like defects in Drosophila melanogaster
Genes expressed in ectoderm and epidermis
*** indicates a special link to ectoderm specific information
The ectoderm is the outer germ layer of the embryo, to be distinguished from the endoderm and mesoderm. Epidermis, derived from ectoderm, is the outer epithelial layer of the embryo, larva and adult; it secretes cuticle, the exoskeleton of the fly.
Prevention of desiccation is a constant challenge for terrestrial organisms. Land insects have an extracellular coat, the cuticle, that plays a major role in protection against exaggerated water loss. This study reports that the ABC transporter Oskyddad (Osy)-a human ABCA12 paralog-contributes to the waterproof barrier function of the cuticle in the fruit fly Drosophila melanogaster. The reduction or elimination of Osy function provokes rapid desiccation. Osy is also involved in defining the inward barrier against xenobiotics penetration. Consistently, the amounts of cuticular hydrocarbons that are involved in cuticle impermeability decrease markedly when Osy activity is reduced. GFP-tagged Osy localises to membrane nano-protrusions within the cuticle, likely pore canals. This suggests that Osy is mediating the transport of cuticular hydrocarbons (CHC) through the pore canals to the cuticle surface. The envelope, which is the outermost cuticle layer constituting the main barrier, is unaffected in osy mutant larvae. This contrasts with the function of Snu, another ABC transporter needed for the construction of the cuticular inward and outward barriers, that nevertheless is implicated in CHC deposition. Hence, Osy and Snu have overlapping and independent roles to establish cuticular resistance against transpiration and xenobiotic penetration. The osy deficient phenotype parallels the phenotype of Harlequin ichthyosis caused by mutations in the human abca12 gene. Thus, it seems that the cellular and molecular mechanisms of lipid barrier assembly in the skin are conserved during evolution (Wang, 2020).
Wang, Y., Norum, M., Oehl, K., Yang, Y., Zuber, R., Yang, J., Farine, J. P., Gehring, N., Flotenmeyer, M., Ferveur, J. F. and Moussian, B. (2020). Dysfunction of Oskyddad causes Harlequin-type ichthyosis-like defects in Drosophila melanogaster. PLoS Genet 16(1): e1008363. PubMed ID: 31929524
Genes involved in tissue development
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