Fig. 9. Model of coordination based on β cell hierarchies.

(A) The functional characterization of islet coordination via optogenetics leads us to propose a hierarchical model for β cell coordination. The coordination involves first-responder cells at the top of the hierarchy, as well as follower cells at the bottom. (B) First-responder β cells are characterized by higher expression of the vitamin B6 production enzyme pnpo. The first-responder β cells are capable of triggering a Ca²⁺ response across many cells. Some β cells present medium to low capability to co-activate other β cells. The rest of the β cells are followers because they present a low capability to recruit β cells. The co-activation capability of the cells and their proportions were determined on the basis of the pooled data from the CheRiff optogenetic analysis.