Marcus Semtner
Microglial G protein signaling
Microglia are the resident immune cells of the brain. Their physiological role is to protect the brain from infection and damage, to promote tissue repair and regeneration, and to nurture neurons and other glial cells by secretion of growth factors, cytokines and other signal molecules. Microglia are also involved in the removal of synapses in the framework of neuronal plasticity in the healthy brain. Some of the microglial processes rest for several minutes and make direct contact with neuronal synapses at a frequency of about one per hour. Neuronal activity regulates the microglial engulfment of synaptic structures, whereas microglial cells preferentially remove less active inputs. My major research interest is to understand how microglia can recognize synaptic activity and how these signals are transduced intracellularly to change microglial morphology and behavior. The primary focus is on signaling through G protein-coupled receptors including those which are linked to calcium ions and those which are linked to cAMP as second messenger. Many of the substances that can influence microglial behavior act on microglial G protein-coupled receptors (e.g. chemokine, complement, hormone, neurotransmitter or purinergic receptors). Thus, the identification of commonalities and differences in microglial G protein signaling will facilitate the future option to estimate the effect of therapeutical drug treatments on immune responses in the brain.