Abstract
Semaphorins, originally discovered as guidance cues for developing axons, are involved in many processes that shape the nervous system during development, from neuronal proliferation and migration to neuritogenesis and synapse formation. Interestingly, the expression of many Semaphorins persists after development. For instance, Semaphorin 3A is a component of perineuronal nets, the extracellular matrix structures enwrapping certain types of neurons in the adult CNS, which contribute to the closure of the critical period for plasticity. Semaphorin 3G and 4C play a crucial role in the control of adult hippocampal connectivity and memory processes, and Semaphorin 5A and 7A regulate adult neurogenesis. This evidence points to a role of Semaphorins in the regulation of adult neuronal plasticity. In this review, we address the distribution of Semaphorins in the adult nervous system and we discuss their function in physiological and pathological processes.
Highlights
The development of complex tissues depends on proliferation, differentiation and migration of cells
Semaphorins constitute a large family of cell guidance cues, which are present in some viruses and conserved across animal species, from worms and flies to humans
In the adult, Sema3A is up-regulated after unilateral lesioning of the olfactory bulb (OB), a manipulation that induces increased olfactory sensory neurons (OSNs) neurogenesis, and there is a temporal correlation between Sema3A expression and the generation of new OSNs
Summary
The development of complex tissues depends on proliferation, differentiation and migration of cells. When adult mice are reared in an enriched environment, a condition known to promote neuronal plasticity (Sale et al, 2014), a strong reduction in PNN CS-GAGs as well as Sema3A expression in PNN is observed in the cerebellar nuclei, in parallel with substantial remodeling of synaptic terminals (Foscarin et al, 2011; Carulli et al, 2013).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call