A bipolar disorder-associated missense variant alters adenylyl cyclase 2 activity and promotes mania-like behavior

The single nucleotide polymorphism rs13166360, causing a substitution of valine 147 to leucine in the adenylyl cyclase 2 (ADCY2), has previously been associated with bipolar disorder (BD). Here we show that this missense mutation diminishes ADCY2 activity by altering its subcellular localization. Mice homozygous for the leucine variant display signs of a mania-like state accompanied by cognitive impairments. Mutant mice are hypersensitive to amphetamine and mania-like behaviors are responsive to lithium treatment. Exposure to chronic social defeat stress switches homozygous leucine variant carriers from a mania- to a depressive-like state. Single-cell RNA-seq revealed widespread expression of ADCY2 in numerous hippocampal cell types. Differentially expressed genes particularly identified from glutamatergic CA1 neurons point towards ADCY2 variant-dependent alterations in multiple biological processes including cAMP-related signaling pathways. These results validate ADCY2 as a BD risk gene providing insights into underlying disease mechanisms potentially opening novel avenues for therapeutic intervention strategies. Single-cell RNA sequencing of ventral hippocampus of wild-type (ADCY2-V151) and mutant (ADCY2-L151) ADCY2 mice.