Abstract
Mechanoreceptors can be motile and actively amplify their mechanical input.[1][,][2][,][3][,][4] We here found that the responses of mechanoreceptor cells can also be shaped actively by contractile supporting cells. Drosophila larvae monitor body movements with pentascolopidial chordotonal (lch5) organs that are stretched out between cuticular attachment sites.[5][,][6][,][7][,][8] These proprioceptive organs contain five stretch-receptor neurons each that receive mechanical stimuli from supporting cap cells. The elastic cap cells are surrounded by extracellular matrix and contain actin cables and non-muscle myosin II motors, suggesting that the cells might be motile.[9][,][10] We show that the supporting cap cells are pre-strained at rest to about twice their relaxed length, and that the force they transmit is modulated by myosin II in the cap cells. Cap cells contracted upon optogenetic activation of myosin II. Cap cell-specific knockdown of the regulatory light chain of myosin II relieved tension and converted the spiking responses of the stretch receptors from phasic to more tonic, impairing adaptation to sustained stimuli. Our findings thus illustrate that mechanoreceptor responses can be actively tailored by contractile neighboring cells.
