A Molecular Trigger for Sea Anemone Stinging

Abstract

Understanding the mechanisms by which cells detect, integrate, and respond to distinct sensory cues is of fundamental importance to biological systems. Cnidarians, such as jellyfish, hydroids, and sea anemones, use specialized stinging cells called nematocytes that facilitate both sensation and secretion during prey capture and defense. Prey-derived mechanical and chemical cues synergistically trigger nematocytes to rapidly fire a venom-covered barb (nematocyst) through a previously unknown mechanism. Here, I show that nematocytes from Nematostella vectensis use a specialized voltage-gated calcium channel (nCaV) to distinguish salient sensory cues and control the explosive discharge response. Unique properties in nCaV confer unusually sensitive, voltage-dependent inactivation to inhibit responses to non-prey signals, such as mechanical water turbulence. Prey-derived chemosensory signals are synaptically transmitted to acutely relieve nCaV inactivation, thereby allowing for mechanically-triggered attack. Thus, the distinct voltage-dependent properties of nCaV allow nematocytes to selectively discriminate prey-derived cues from environmental noise. These findings reveal a molecular basis for the cnidarian stinging response and highlight how single proteins can integrate diverse cellular signals to mediate discrete behaviors.