Calcium signaling in retinal glia

The retina is a thin layer of transparent tissue made up of neurons and non-neural cells that are responsible for converting visual images into electrical signals. These electrical signals are transmitted to the brain via the optic nerve and result in our visual perception. The primary non-neural cells in the retina are glial cells. There are two different types of glial cells in the retina: Müller glia and astrocytes. Müller glia are the principal glial cell type in the vertebrate retina and are radial glia that span three synaptic layers. Müller glia provide important homeostatic functions, including neurotransmitter uptake and buffering of ions released during neuronal activity. In addition, Müller glia also directly participate with neurons in bidirectional communication. They do this by responding to released neurotransmitters and, in turn, releasing glial transmitters and neuroactive molecules that can have effects on retinal neurons and vasculature. Receptor-activated calcium increases are key to the response of these cells to neurotransmitters and to the subsequent release of glial transmitters. Increases in calcium in Müller glia involve calcium release from intracellular stores and calcium entry across the cell membrane. Alterations in Müller glia calcium signaling are associated with gliosis, a condition in which quiescent Müller glia in the postnatal retina proliferate in response to injury. Our research is examining the cellular pathways, specifically calcium entry channels, involved in receptor-activated calcium increases in Müller glia and the relationship between glial calcium signals and cell proliferation. These studies will provide new knowledge about glial cell signaling in the retina and are fundamental for understanding the role of glial cells in retinal physiology and pathophysiology.