Epidermal keratinocyte polarity and motility require Ca2+ influx through TRPV1

Ca(2+) has long been known to play an important role in cellular polarity and guidance. We studied the role of Ca(2+) signaling during random and directed cell migration to better understand whether Ca(2+) directs cell motility from the leading edge and which ion channels are involved in this function by using primary zebrafish keratinocytes. Rapid line-scan and time-lapse imaging of intracellular Ca(2+) (Ca(2+)i) during migration and automated image alignment enabled us to characterize and map the spatiotemporal changes in Ca(2+)i. We show that asymmetric distributions of lamellipodial Ca(2+) sparks are encoded in frequency, not amplitude, and that they correlate with cellular rotation during migration. Directed migration during galvanotaxis increases the frequency of Ca(2+) sparks over the entire lamellipod; however, these events do not give rise to asymmetric Ca(2+)i signals that correlate with turning. We demonstrate that Ca(2+)-permeable channels within these cells are mechanically activated and include several transient receptor potential family members, including TRPV1. Last, we demonstrate that cell motility and Ca(2+)i activity are affected by pharmacological agents that target TRPV1, indicating a novel role for this channel during cell migration.