Conserved proteins link sensory input and metamorphosis in a marine chordate
Anoctamins play a key role in sensory perception in mammals. A new article by the Chatzigeorgiou group reveals their dual role in perception and larval metamorphosis in the chordate Ciona.
Main content
Many marine invertebrates that live in our oceans have a biphasic life cycle, with a free swimming larva and a sessile adult. The larval stage is key for species鈥� dispersal, as larvae take advantage of the water currents to travel in search of a new place to settle and metamorphose into a fertile adult.
using the invertebrate chordate Ciona intestinalis identified the neurons and neural circuits mediating the process of settlement and metamorphosis in response to various mechanical and chemical cues. However, the signaling cascade involved in sensing these cues remained elusive. and led by PhD graduate , the team identified two molecules in the conserved Anoctamin/Tmem16 family - Ano5 and Ano6 鈥� as key players in this signaling cascade. In humans, these proteins are involved in numerous pathological conditions, including neurological diseases.
鈥淭he most significant breakthrough in this paper is the discovery that Anoctamins play a dual role in Ciona intestinalis by both enabling听polymodal sensory perception听- detecting multiple types of environmental signals - and driving听larval metamorphosis鈥�, Liang explained. 鈥淭his reveals a new evolutionary link between sensory functions and developmental changes.鈥�
"Our work reveals a new evolutionary link between sensory functions and developmental changes"
- Zonglai Liang
Using transgenic reporters, Liang was able to show that Ano5 and Ano6 genes are expressed in the papillae, the adhesive sensory organs of Ciona larvae. Polymodal sensory cells within the papillae are important for sensing the mechanical and chemical cues guiding postembryonic development. Combining CRISPR/Cas9 genome editing and quantitative behavioral analysis, he also showed that the two proteins were required for both settlement and metamorphosis behaviors. 鈥淢y favorite experiment in this study was when we used live imaging to observe the sensory behavior of Ciona larvae and analyzed their responses to environmental stimuli using an AI-based tool. This experiment was not only fascinating but also a key to our discoveries because it directly showed how Anoctamins enable the larvae to sense their environment and trigger metamorphosis鈥�, Liang said.
In addition, he collaborated with the group鈥檚 former chief engineer to carry out calcium imaging experiments as well as chemogenetic and pharmacological perturbations. These complementary approaches all pointed to a crucial role for Ano5 and Ano6 in the neuronal responses to stimuli, and showed that they cooperate with specific proteins in the cellular calcium machinery to modulate larval metamorphosis.
The study brings new light on the evolution of sensory systems and developmental processes, and on their intricate connection. 鈥淲e now have a better understanding of which signaling pathways are involved in sensory perception of metamorphic cues鈥�, group leader Marios Chatzigeorgiou said. 鈥淕iven that Anoctamins are highly conserved molecules, and recent studies showing that mammalian Anoctamins are involved in sensory perception, we can reasonably hypothesize that the role of Anoctamins in sensory transduction evolved early in the chordate lineage.鈥�
听
