Table 1.

Proteins in the CNS extracellular matrix that contribute to the inhibition of neuroregeneration after injury

Inhibitory protein	Function	Complementary receptors
Nogo-A	Remyelination inhibitor via the RhoA pathway	Nogo-66 terminus: NgR1, p75, TROY and LINGO1 Amino-Nogo terminus: unknown
MAG	Remyelination inhibitor via the RhoA pathway	NgR2, GT1b, NgR1, p75, TROY and LINGO1
OMgp	Remyelination inhibitor via the RhoA pathway	NgR1
Versican (CSPG2)	Important during inflammation as it interacts with inflammatory leukocytes and inflammatory cells recruiting chemokines. It also stabilizes perineuronal nets to stabilize synaptic connections.	N-terminus: hyaluronan in the extracellular matrix (ECM) C-terminus: Ligands in ECM, especially tenascin [75]
NI-35	Nonpermissive growth factor in myelin	Unknown
Ephrin B3 [71]	Inhibits remyelination	EphA4
Semaphorin 4D (Sema 4D) [71]	Inhibits remyelination	PlexinB1
Semaphorin 3A (Sema 3A) [76–78]	In scars in both PNS and CNS injuries	Nrp1, Nrp2, L1cam, Nrcam [79]

NgR1 Neuronal Nogo-66 receptor 1, LINGO1 Leucine rich repeat and Immunoglobin-like domain-containing protein 1, p75 neurotrophin receptor, TROY Tumor necrosis factor receptor superfamily, member 19, RhoA Ras homolog family member A, MAG Myelin-associated glycoprotein, GT1b Trisialoganglioside protein, OMgp Oligodendrocyte-myelin glycoprotein, CSPG2 chondroitin sulfate proteoglycan core protein 2 or versican, ECM extracellular matix, NI-35 A CNS myelin-associated neurite growth inhibitor, EphA4 Ephrin type-A receptor 4, Nrp1 Neuropilin 1, Nrp2 Neuropilin 2, L1cam L1 cell adhesion molecule, Nrcam Neuronal cell adhesion molecule