Laminin-332 coordinates mechanotransduction and growth cone bifurcation in sensory neurons.

Laminin-332 is a major component of the dermo-epidermal skin basement membrane and maintains skin integrity. The transduction of mechanical force into electrical signals by sensory endings in the skin requires mechanosensitive channels. We found that mouse epidermal keratinocytes produce a matrix that is inhibitory for sensory mechanotransduction and that the active molecular component is laminin-332. Substrate-bound laminin-332 specifically suppressed one type of mechanosensitive current (rapidly adapting) independently of integrin-receptor activation. This mechanotransduction suppression could be exerted locally and was mediated by preventing the formation of protein tethers necessary for current activation. We also found that laminin-332 could locally control sensory axon branching behavior. Loss of laminin-332 in humans led to increased sensory terminal branching and may lead to a de-repression of mechanosensitive currents. These previously unknown functions for this matrix molecule may explain some of the extreme pain experienced by individuals with epidermolysis bullosa who are deficient in laminin-332.