Matrix metalloproteinasa-9 increases NMDA receptor lateral diffusion

Matrix metalloproteinase-9 (MMP-9) has emerged as a physiological regulator of NMDA receptor (NMDAR)-dependent synaptic plasticity and memory. The pathways by which MMP-9 affects NMDAR signaling remain, however, not well understood. Using single Quantum Dot tracking we demonstrate that MMP-9 enzymatic activity increases NR1-NMDAR surface traffi cking but has no infl uence on AMPA receptor (AMPAR) mobility. Other extracellular protease – Cathepsin G has no effect on both NMDAR and AMPAR lateral diffusion. The mechanism of MMP-9 action on NMDAR is caused neither by change in overall extracellular matrix (ECM) structure, nor by cleavage of NMDAR subunits, but by infl uence on integrinbeta 1 signaling. These fi ndings describe a new target pathway for MMP-9 action in key physiological and pathological brain processes.