Regulation of Life Extension Factor Klotho on Depressive-like Behaviors via Modulation of GluN2B Function in the Nucleus Accumbens

Klotho is a life extension factor that has an ability to regulate the function of GluN2B-containing N-methyl-D-aspartate receptors (NMDARs), whose dysfunction in the nucleus accumbens (NAc) underlies critical aspects of the pathophysiology of major depression. Here we study the functional relevance of klotho in the pathogenesis of depression. A chronic social defeat stress paradigm, where mice are either categorized as susceptible or unsusceptible group based on their performance in a social interaction test, was used in this study. We found that the expression of klotho was largely decreased in the NAc of susceptible mice when compared to control or unsusceptible group. Genetic knockdown of klotho in the NAc induced depressive-like behaviors in naive mice, while overexpression of klotho produced an antidepressive effect in normal mice and ameliorated the depressive-like behaviors in susceptible mice. Molecularly, knockdown of klotho in the NAc resulted in selective decreases of total and synaptic GluN2B expression that were identical to susceptible mice. Elevation of klotho in the NAc reversed the reductions of GluN2B expressions, as well as altered synaptic transmission and spine density in the NAc of susceptible mice. Furthermore, blockade of GluN2B with a specific antagonist abolished the beneficial effects of klotho elevation in susceptible mice. Collectively, we demonstrated that klotho in the NAc modulates depressive-like behaviors by regulating the function of GluN2B-containing NMDARs. These results reveal a novel role for klotho in the pathogenesis of depression, opening new insights into the molecular basis of major depression.