CHONDROITIN SULFATE PROTEOGLYCAN-5 FORMS PERISYNAPTIC MATRIX ASSEMBLIES IN SELECT MICRODOMAINS OF THE ADULT CORTEX
1 Department of Anatomy, Semmelweis University, Budapest, Hungary; ; 2SE NAP B Research Group of Experimental Neuroanatomy and Developmental Biology, Semmelweis University, Budapest, Hungary; 3Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
Composition of the brain extracellular matrix changes in time as maturation proceeds. Chondroitin sulfate proteoglycan 5 (CSPG-5), also known as neuroglycan C, has been previously associated to differentiation since it shapes neurite growth and synapse forming. Here, we show that this proteoglycan persists throughout adulthood and subsides in select cortical microdomains. Progressively accumulating postnatally, CSPG-5 concentrates around the terminals of specific, but less so of monoaminergic or cholinergic afferents of the archi- and neocortex. Neurons, but not glial cells, externalize CSPG-5 and restrict this load to future post- and presynaptic compartments. In the adult cortex, CSPG-5 containing perisynaptic rings appear adjacent to, but not embedded in perineuronal nets, the latter being the typical somatodendritic postsynaptic matrix coat of neurons. CSPG-5 expression is high in cortical regions with plastic properties, including hippocampus and the medial prefrontal cortex. Its identified shift in the medial prefrontal cortex of suicide subjects may reflect an impact in the pathogenesis of psychiatric diseases or support diagnostic power.