Targeted deletion of the C-terminus of the mouse adenomatous polyposis coli tumor suppressor results in neurologic phenotypes related to schizophrenia

Background: Loss of adenomatous polyposis coli (APC) gene function results in constitutive activation of the canonical Wnt pathway and represents the main initiating and rate-limiting event in colorectal tumorigenesis. APC is likely to participate in a wide spectrum of biological functions via its different functional domains and is abundantly expressed in the brain as well as in peripheral tissues. However, the neuronal function of APC is poorly understood. To investigate the functional role of Apc in the central nervous system, we analyzed the neurological phenotypes of Apc(1638T/1638T) mice, which carry a targeted deletion of the 3' terminal third of Apc that does not affect Wnt signaling. Results: A series of behavioral tests revealed a working memory deficit, increased locomotor activity, reduced anxiety-related behavior, and mildly decreased social interaction in Apc(1638T/1638T) mice. Apc(1638T/1638T) mice showed abnormal morphology of the dendritic spines and impaired long-term potentiation of synaptic transmission in the hippocampal CA1 region. Moreover, Apc(1638T/1638T) mice showed abnormal dopamine and serotonin distribution in the brain. Some of these behavioral and neuronal phenotypes are related to symptoms and endophenotypes of schizophrenia. Conclusions: Our results demonstrate that the C-terminus of the Apc tumor suppressor plays a critical role in cognitive and neuropsychiatric functioning. This finding suggests a potential functional link between the C-terminus of APC and pathologies of the central nervous system.