Negative Regulator of MAP Kinase is Increased in Depression and Is Necessary and Sufficient for Expression of Depressive Behavior

Lifetime prevalence (~16%)1 and the economic burden ($100 billion annually)2,3 associated with major depressive disorder (MDD) make it one of the most common and debilitating neurobiological illnesses. To date, the exact cellular and molecular mechanisms underlying the pathophysiology of MDD have not been identified. Here we use whole genome expression profiling of postmortem tissue and demonstrate significantly increased expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) in the hippocampal subfields of MDD subjects compared to matched controls. MKP-1, also known as DUSP1, is a member of a family of dual-specificity phosphatases (DUSP) that dephosphorylate both threonine and tyrosine residues and thereby serves as a key negative regulator of MAPK cascade4, a major signaling pathway involved in neuronal plasticity, function and survival5,6. The significance of altered MKP-1 was tested in rodent models of depression and demonstrates that increased hippocampal MKP-1 expression, as a result of stress or viral-mediated gene transfer, causes depressive behaviors. Conversely, chronic antidepressant treatment normalizes the stress-induced MKP-1 expression and behavior, and mice lacking MKP-1 are resilient to stress. These postmortem and preclinical studies identify MKP-1 as a critical factor in MDD pathophysiology and as a novel target for therapeutic interventions.