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| Cuticle Differentiation | ||
The physiological and barrier functions of many epithelia rely among others on their apical extracellular matrices (aECM). A central element mediating and organising aECM production and integrity is the apical plasma membrane that often adopts a typical topology implying asymmetric distribution of determinants within the plasma membrane. Using the exoskeleton of the larva of fruit fly Drosophila melanogaster called the cuticle as a model aECM, we are studying the genetic and molecular mechanisms of apical plasma membrane shaping and function following a comparative approach. Indeed, cuticle architecture varies in different larval tissues the epidermis, the tracheae and the gut epithelia according to their needs: for example, the foregut cuticle is largely hardened (sclerotised) as it is used to chew food, whereas most parts of the body cuticle are elastic allowing flexible locomotion through rotten fruits. Consistently, the apical plasma membrane in different tissues has to be adequately equipped to coordinate the specific as well as common molecular mechanisms. In particular, we are focussing on the function of membrane-associated factors and the regulation of their activity in different cuticle-producing tissues during development. At the moment, we are performing a genetic screen to identify factors required for apical plasma membrane shaping and function. Our findings will contribute to the understanding of basic biological mechanisms that are essential for the function of epithelia. |
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Fig. 1: The Drosophila larva has a soft body cuticle. Only the head skeleton and the ventral denticles are hard and tanned. The Drosophila larval cuticle produced during embryogenesis is a typical arthropod cuticle with three horizontal layers that are defined by their biochemical composition. The procuticle (pro) is the inner chitin-protein matrix that is attached to the apical surface (apical plasma membrane, apm) of the epithelial cell. It is overlain by the protein-network of the epicuticle (epi). The outermost envelope (env) with five alternating electron-dense and electron-lucid sheets faces the environment. |
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Fig. 2: During cuticle differentiation, the apical plasma membrane forms repetitive corrugations called apical undulae. One unit of apical undulae consists of a crest, which is the site of chitin synthesis, and a slope, which is the site of protein secretion. Cuticle assembly and organisation occurs to a large extent also in the extracellular space, where enzymes cross-link the components (proteins, catceholamines, lipids and chitin) to construct a barrier. |
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The group is financed by the Deutsche Forschungsgemeinschaft |
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Group members Principal investigator: PhD students:
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Recent Publications: U. Gangishetti, J. Veerkamp, D. Bezdan, H. Schwarz, I. Lohmann, B. Moussian. 2012.
The transcription factor Grainy head and the steroid hormone ecdysone cooperate during differentiation of the skin of Drosophila melanogaster. Insect Mol Biol In press. |
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