Glial cells perform many essential roles in the nervous system but how are their numbers controlled during development? Here (p. 5201), Venugopala Reddy and Kenneth Irvine report that glial cell proliferation in Drosophila is regulated by Hippo signalling, a conserved signalling pathway that controls organ growth and size. They show that Yorkie, the transcriptional co-activator of Hippo, is necessary for normal glial cell numbers and drives glial cell overproliferation when overexpressed. Yorkie activity in glial cells, they report, is controlled by a Merlin-Hippo signalling pathway; other upstream regulators of Hippo (for example, Fat) play no detectable role in glial cell proliferation. They also show that Yorkie affects glial cell proliferation by promoting the expression of the microRNA gene bantam, which, in turn, promotes Myc expression. Because homologues of Merlin, Yorkie and Myc are implicated in human glioma development, the authors suggest that the regulatory links identified here could represent a conserved pathway for the control of glial cell proliferation.

© 2011.