Effective neuron-microglial communication is a prerequisite to achieve the final connectome. It is mediated by both the formation of new synapses and selective removal of unnecessary connections through synaptic pruning. Recent evidences suggest that superfluous connections are eliminated by microglia. Almost 70% of the connections are lost in a primate cortex within six months of life. But what drives this selective elimination of so many synapses is a million-euro question. Identifying neuronal signals that differentiate weak synapses from the strong ones is an emerging frontier in cellular neuroscience. Several eat-me signals in synaptic pruning have been identified, but spare-me signals that limit phagocytic elimination of synapses are yet to be explored. Sialic acids on neuronal glycocalyx acts as spare-me signal and prevents microglial phagocytosis through Siglec receptors. Aberrant regulation of sialic acid caused neuronal loss and embryonic lethality. It is also becoming evident that sialic acid plays a key role in neurodevelopment, but the cellular and molecular mechanisms by which it regulates neurodevelopment is yet to be explored. This makes sialic acid an ideal candidate to evaluate its role in neurodevelopment. Hence, we aimed to interrogate whether sialidases and glycocalyx recognizing targets are developmentally regulated; and also, to define the role of sialic acid during microglial-mediated synaptic pruning in a developmental context. This paves a path to identify cellular and molecular mechanisms by which glycocalyx composition defines neuron-microglia interactions and thus circuit refinement through synaptic pruning. Since Marie Skłodowska-Curie Actions offer attractive career developmental opportunities, the global aim of this EU-funded grant was to also to enhance the researcher’s potential through training in all aspects of scientific research besides neuroscience.
