{Reference Type}: Journal Article {Title}: Constitutive Activity of Serotonin Receptor 6 Regulates Human Cerebral Organoids Formation and Depression-like Behaviors. {Author}: Wang Q;Dong X;Hu T;Qu C;Lu J;Zhou Y;Li J;Pei G; {Journal}: Stem Cell Reports {Volume}: 16 {Issue}: 1 {Year}: 01 2021 12 {Factor}: 7.294 {DOI}: 10.1016/j.stemcr.2020.11.015 {Abstract}: Serotonin receptor 6 (5-HT6R), a typical G protein-coupled receptor (GPCR) mainly expressed in the neurogenic area with constitutive activity, is of particular interest as a promising target for emotional impairment. Here, we found that 5-HT6R was highly expressed in human NSCs and activation of the receptor promoted self-renewal of human NSCs, and thus induced the expansion and folding of human cerebral organoids; dysfunction of receptor or inhibition of its constitutive activity resulted in the premature differentiation of NSCs, which ultimately depleted the NSC pool. The following mechanistic study revealed that EPAC-CREB signaling was involved in 5-HT6R regulation. Furthermore, we showed that mice with genetic deletion of 5-HT6R or knockin A268R mutant presented depression-like behaviors and impaired hippocampal neurogenesis for progressive decrease of the NSC pool. Thus, this study indicates that the modulation of 5-HT6R and its constitutive activity may provide a therapeutic alternative to alleviate depression.