How Merkel cells transduce mechanical stimuli: A biophysical model of Merkel cells

by Fangtao Mao, Wenzhen Yang

Merkel cells combine with Aβ afferents, producing slowly adapting type 1(SA1) responses to mechanical stimuli. However, how Merkel cells transduce mechanical stimuli into neural signals to Aβ afferents is still unclear. Here we develop a biophysical model of Merkel cells for mechanical transduction by incorporating main ingredients such as Ca²⁺ and K⁺ voltage-gated channels, Piezo2 channels, internal Ca²⁺ stores, neurotransmitters release, and cell deformation. We first validate our model with several experiments. Then we reveal that Ca²⁺ and K⁺ channels on the plasma membrane shape the depolarization of membrane potentials, further regulating the Ca²⁺ transients in the cells. We also show that Ca²⁺ channels on the plasma membrane mainly inspire the Ca²⁺ transients, while internal Ca²⁺ stores mainly maintain the Ca²⁺ transients. Moreover, we show that though Piezo2 channels are rapidly adapting mechanical-sensitive channels, they are sufficient to inspire sustained Ca²⁺ transients in Merkel cells, which further induce the release of neurotransmitters for tens of seconds. Thus our work provides a model that captures the membrane potentials and Ca²⁺ transients features of Merkel cells and partly explains how Merkel cells transduce the mechanical stimuli by Piezo2 channels.