Phosphatase Signaling as a Therapeutic Strategy in Schizophrenia

Cognitive impairment in schizophrenia remains insufficiently addressed by existing treatments. Current FDA-approved therapies primarily modulate neurotransmitter systems, resulting in incomplete symptom control and substantial adverse effects. There is therefore a critical need for therapeutic strategies that more directly address the intracellular signaling mechanisms underlying synaptic dysfunction and cognitive deficits in schizophrenia. Protein phosphatases represent an essential but historically underexplored class of signaling enzymes that regulate phosphorylation-dependent control of synaptic receptor trafficking, plasticity, and neuronal circuit function. Although multiple phosphatases have been implicated in schizophrenia through genetic, post-mortem, and functional studies, their therapeutic targeting has been limited by challenges related to selectivity, cellular permeability, and pleiotropy. Here, we review the etiology of schizophrenia and limitations of current pharmacological approaches, synthesize evidence linking specific protein phosphatases to schizophrenia pathophysiology, and discuss emerging strategies, including allosteric modulation and targeted protein degradation, that may enable selective intervention in phosphatase-driven signaling pathways. We highlight the striatal-enriched tyrosine phosphatase STEP (PTPN5) as a case study illustrating how selective phosphatase modulation can restore synaptic signaling in schizophrenia-relevant models.