Data Catalog

Glial cells play structural and functional roles central to the formation, activity and integrity of neurons throughout the nervous system. Here, using the genetic model Drosophila melanogaster, reseearchers identify a new glial cell type in one of the most active tissues in the nervous system—the retina. These cells, called ommatidial cone cells (or Semper cells), were previously recognized for their role in lens formation. Using cell-specific molecular genetic approaches, this study demonstrates that cone cells (CCs) also share molecular, functional, and genetic features with both vertebrate and invertebrate glia to prevent light-induced retinal degeneration and provide structural and physiological support for photoreceptors.

Multiple cell types can be specified from a single pool of progenitors through the combinatorial activity of transcriptional regulators, which activate distinct developmental programs to establish different cell fates. The zinc finger transcription factor Glass is required for neuronal progenitors in the Drosophila eye imaginal disc to acquire a photoreceptor identity. Glass is also expressed in non-neuronal cone and pigment cells, but its role in these cells is unknown. To examine how Glass activity is affected by the cellular context, the researchers misexpressed it in different tissues. When expressed in neuroblasts of the larval brain or in epithelial cells of the wing disc, Glass activated both a common core set of target genes and distinct gene sets specific to each tissue. In addition to photoreceptor-specific genes, Glass induced markers of cone and pigment cells. Cell type-specific glass mutations generated in cone or pigment cells using somatic CRISPR revealed autonomous developmental defects, and expressing Glass specifically in these cells partially rescued glass mutant phenotypes. Glass thus acts in both neuronal and non-neuronal cells to promote their differentiation into functional components of the eye, suggesting that it is a determinant of organ identity.