Figure 4.

Methylation of arginine residues on histones by protein arginine methyltransferases (PRMT)8. (a) Methylation by PRMTs can either lead to transcriptional activation or transcriptional repression. In the case of the structural protein Tenascin‐R (TNR), methylation by PRMT8 suppresses its expression. TNR proteins are crucial in extracellular complexes organization for the formation of perineuronal nets (PNN). PNNs wrap around parvalbumin (PV) interneurons and consolidate neuronal circuitry acting as a structural break for critical period plasticity. (b) PRMT knockouts lack this suppression of the Tnr gene resulting in the increase in TNR protein synthesis. This in effect hastens PNN formation in mice visual cortex resorting to the premature closure of critical period.