Abstract
The extracellular matrix (ECM), a structure contributed to and commonly shared by many cells in an organism, plays an active role during morphogenesis. Here, we used the Drosophila tracheal system to study the complex relationship between the ECM and epithelial cells during development. We show that there is an active feedback mechanism between the apical ECM (aECM) and the apical F-actin in tracheal cells. Furthermore, we reveal that cell-cell junctions are key players in this aECM patterning and organisation and that individual cells contribute autonomously to their aECM. Strikingly, changes in the aECM influence the levels of phosphorylated Src42A (pSrc) at cell junctions. Therefore, we propose that Src42A phosphorylation levels provide a link for the ECM environment to ensure proper cytoskeletal organisation.
Highlights
How do individual cells participate in the generation of a supracellular extracellular matrix (ECM) with an overall common organisation that overruns cellular borders?. We have addressed these issues by studying the apical ECM of Drosophila melanogaster trachea, the insect respiratory system
We show that cell-cell junctions participate in organising F-actin bundles and the taenidial fold supracellular apical ECM (aECM) and that this chitinous aECM contributes to regulating F-actin organisation in a two-way regulatory mechanism
We focused on the main branch of the trachea, the dorsal trunk (DT), where taenidia are more conspicuous
Summary
“The anatomically internal lining of the trachea consists of a chitinous layer which presents what is usually termed a ’spiral thickening’, but whose form is really that of a helicoid. (...) we have to explain just how it is that the cells of the tracheal epithelium can cooperate unconsciously so as to form a helicoid thickening continuous from one end of the trachea to another, especially since each cell produces not merely one section of the continuous filament, but several parallel sections of unequal length.” (Thompson, 1929). Cell biology Developmental biology and stem cells eLife digest Animal cells can secrete proteins and molecules into the space around them to create a support they can attach to This structure – known as the extracellular matrix – comes in various forms and can help to shape tissues or influence the way in which cells behave. Once this network is complete, these cells secrete the materials to make an extracellular matrix in the internal (apical) surface of the tubes This matrix has a series of spiralling ridges made from a molecule called chitin. Ozturk-Colak et al find evidence of a “feedback” mechanism, in which the presence of chitin reduces the activity of Src42A to maintain the correct patterning of actin These findings reveal that actin and junctions between cells play a central role in co-ordinating the formation of the extracellular matrix in fruit fly airways. We show that cell-cell junctions participate in organising F-actin bundles and the taenidial fold supracellular aECM and that this chitinous aECM contributes to regulating F-actin organisation in a two-way regulatory mechanism
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