Cell migration in the fruitfly

In a special edition of the journal Current Opinion in Cell Biology on the topic of cell adhesion and migration, Daria Siekhaus, Professor at IST Austria, as well as Postdoc Aparna Ratheesh and PhD student Vera Belyaeva, both members of the Siekhaus group, review cell migration and adhesion of immune cells in the fruitfly Drosophila. 

The majority of immune cells in Drosophila, namely 95%, are plasmatocytes. They are similar to macrophages, a type of vertebrate immune cell, in both function and development. In their review, the authors illustrate the similarities found between plasmatocytes and macrophages. Both plasmatocytes and macrophages migrate along similar routes during the development of fruitflies and vertebrates, respectively. During this migration, they are both likely to be guided by orthologous receptors. Both cell types play similar important roles during organ development: while macrophages for example facilitate proper branching of kidneys, plasmatocytes are important for the positioning of renal tubules in the fruitfly.

Like macrophages, plasmatocytes fight infections. To carry out this function, both cell types have to adhere to special niches in the respective organisms. During uncontrolled tumor growth in the fruitfly, plasmatocytes can react by encapsulating and blocking the tumor or by promoting tumor growth, depending on the type of tumor involved. The latter response is similar to that of macrophages, which can enhance tumor functions in vertebrates.  

The authors conclude that the molecular mechanisms which regulate movement, adhesion and functions of the fruitfly immune system and plasmatocytes may be ancient programs upon which evolution has elaborated to permit the complex repertoire of immune cell behaviors and functions seen in vertebrates.