title: The chemorepulsive axon guidance protein semaphorin3A is a constituent of perineuronal nets in the adult rodent brain.
abstract: In the adult rodent brain, subsets of neurons are surrounded by densely organised extracellular matrix called perineuronal nets (PNNs). PNNs consist of hyaluronan, tenascin-R, chondroitin sulphate proteoglycans (CSPGs), and the link proteins Crtl1 and Bral2. PNNs restrict plasticity at the end of critical periods and can be visualised with Wisteria floribunda agglutinin (WFA). Using a number of antibodies raised against the different regions of semaphorin3A (Sema3A) we demonstrate that this secreted chemorepulsive axon guidance protein is localised to WFA-positive PNNs around inhibitory interneurons in the cortex and several other PNN-bearing neurons throughout the brain and co-localises with aggrecan, versican, phosphacan and tenascin-R. Chondroitinase ABC (ChABC) was injected in the cortex to degrade glycosaminoglycans (GAGs) from the CSPGs, abolishing WFA staining of PNNs around the injection site. Sema3A-positive nets were no longer observed in the area devoid of WFA staining. In mice lacking the link protein Crtl1 in the CNS only vestigial PNNs are present, and in these mice there were no Sema3A-positive PNN structures. A biochemical analysis shows that Sema3A protein binds with high-affinity to CS-GAGs and aggrecan and versican extracted from PNNs in the adult rat brain, and a significant proportion of Sema3A is retrieved in brain extracts that are enriched in PNN-associated GAGs. The Sema3A receptor components PlexinA1 and A4 are selectively expressed by inhibitory interneurons in the cortex that are surrounded by Sema3A positive PNNs. We conclude that the chemorepulsive axon guidance molecule Sema3A is present in PNNs of the adult rodent brain, bound to the GAGs of the CSPGs. These observations suggest a novel concept namely that chemorepulsive axon guidance molecules like Sema3A may be important functional attributes of PNNs in the adult brain.
authors.affiliation: Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.
authors.forename: Tam
authors.initials: T
authors.lastname: Vo
authors.forename: Daniela
authors.initials: D
authors.lastname: Carulli
authors.forename: Erich M E
authors.initials: EM
authors.lastname: Ehlert
authors.forename: Jessica C F
authors.initials: JC
authors.lastname: Kwok
authors.forename: Gunnar
authors.initials: G
authors.lastname: Dick
authors.forename: Vasil
authors.initials: V
authors.lastname: Mecollari
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Moloney
authors.forename: Gera
authors.initials: G
authors.lastname: Neufeld
authors.forename: Fred
authors.initials: F
authors.lastname: de Winter
authors.forename: James W
authors.initials: JW
authors.lastname: Fawcett
authors.forename: Joost
authors.initials: J
authors.lastname: Verhaagen
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007395:Interneurons / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D011485:Protein Binding; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D040121:Semaphorin-3A / Q000235:genetics / Q000378:metabolism*; D053675:Versicans / Q000378:metabolism; D000099249:Proteoglycan Link Protein
chemical_list: D053674:Aggrecans; D016326:Extracellular Matrix Proteins; D006025:Glycosaminoglycans; D011509:Proteoglycans; D040121:Semaphorin-3A; D053675:Versicans; D000099249:Proteoglycan Link Protein