Identification of new glial cell specific gene functions. Imke Schmidt, Silke Thomas, Christian Klämbt. Institute for neurobiology, University of Münster, Münster, Nordrhein-Westfalen, Germany.
Main functional features of the nervous system have been conserved during evolution. Likewise the biology of neurons and glial cells is remarkable similar in different animal species. The interaction of these two cell types is crucial for the correct formation and subsequent functionality of the neural circuit. Important supportive functions including the insulation and support of neurons, the facilitation and modulation of electrical conductance and synaptic transmission are performed by glial cells. In the embryo and the larval nervous system of Drosophila every segmental unit of the ventral nerve cord contains only 65 glial cells. Due to this lower complexity and a manageable number of glial cells Drosophila represents a well-suited model system to study glial cell biology. To get further insights into Drosophila glial cell biology we performed a glial cell specific RNAi Screen. So far we screened about 5,000 different genes for a cell autonomous requirement in all glia using the panglial driver line repoGal4. The knock down of about 14% of the tested genes leads to lethality. Interestingly, we noted in about 1% of the cases flies with reduced viability and locomotion defects. To determine whether the function of these 800 candidate genes can be attributed to a specific glial cell class we silenced their expression using Gal4 driver lines specific to individual glial cell types (perineurial glia, subperineurial glia, wrapping glia and astrocytic glia). The knock down of kinesin heavy chain (Khc) or tubulin severely affects viability and renders the flies hyperactive. Khc is a well known protein and has been thoroughly analyzed for its role in anterograde axonal transport. In glial cells a function of Khc has been recently described (Lyons et al., 2009). In Drosophila loss of Khc in glial cells disrupts transport of mitochondria and leads to a cell-autonomous differentiation defect during early larval stages. A model describing Khc function in Drosophila glia will be discussed.