Expression analyses of Phactr1 (phosphatase and actin regulator 1) during mouse brain development.

Phactr1 (Phosphatase and actin regulator 1) is abundantly expressed in the central nervous system and considered to regulate various neuronal processes through the regulation of protein phosphorylation and actin cytoskeletal organization. In this study, we prepared a specific antibody against Phactr1, anti-Phactr1, and carried out biochemical and morphological analyses of Phactr1 with mouse brain tissues. Western blotting analyses revealed that Phactr1 was expressed in a tissue-dependent profile in the young adult mouse and in a developmental stage-dependent manner in the mouse brain. In primary cultured hippocampal neurons, while Phactr1 was diffusely distributed in the nucleus and cytoplasm, it was visualized in axon and dendrites with partial colocalization with synapses. Phactr1 was also detected in the synaptosomal and postsynaptic density fractions in biochemical fractionation. Immunohistochemical analyses clarified that Phactr1 was differentially expressed in cortical neurons during corticogenesis; the protein was frequently accumulated in the nucleus at the embryonic stage while it came to diffusely distribute in the cell body at the prepubertal stage. The obtained results suggest that Phactr1 takes part in neuronal functions regulated in a spatiotemporal manner.