IDENTIFICATION OF PROTEINS INTERACTING WITH CYCLASE-ASSOCIATED PROTEIN 1 (CAP1) IN NEURONS

Cytoskeletal dynamics is tightly controlled and coordinates neuronal connectivity and circuit assembly. Actin represents the major cytoskeletal protein in neurons and plays a crucial role in neural network formation by regulating structural plasticity and synaptic integration. Alterations in actin dynamics have been associated with neurodevelopmental and neuropsychiatric disorders. Cyclase-associated protein 1 (CAP1) is a highly conserved actin-binding protein (ABP) that is expressed during neuronal differentiation and that contributes to the formation and function of neural networks. By interacting with other proteins, CAP1 regulates actin dynamics and enables the cytoskeletal plasticity required for neuronal development, synaptic function, as well as the establishment and maintenance of the neuronal network. To elucidate the molecular mechanisms underlying CAP1 function, we performed a pull-down assay and mass spectrometry analyses on cerebral cortex and hippocampal lysates from postnatal day 40 (P40) mice in order to identify CAP1 interaction partners involved in the regulation of actin dynamics. We conducted validation experiments that confirmed the interaction with CAP1 for 7 out of 11 candidate proteins in HT22 overexpression system. Subsequent analyses in P40 mouse brain lysates from hippocampus, cortex and cerebellum, revealed that only a subset of these candidates interacts with CAP1 in vivo. By exploiting CAP1 deletion mutants, we are currently mapping the CAP1 domains required for these interactions. From our experiments, we expect to provide novel insights into the mechanisms that control neuronal actin dynamics relevant for the formation of neuronal networks, that may be dysregulated in human neurodevelopmental and psychiatric disorders.