Pyridoxal‐5′‐phosphate phosphatase/chronophin inhibits long‐term potentiation induction in the rat dentate gyrus

Pyridoxal‐5′‐phosphate (PLP)‐phosphatase/chronophin (PLPP/CIN) directly dephosphorylates actin‐depolymerizing factor (ADF)/cofilin as well as PLP. Although PLPP/CIN plays a role in the regulation of F‐actin and vitamin B₆ metabolism, there is no direct evidence to support a correlation between PLPP/CIN and F‐actin polymerization during long‐term potentiation (LTP) induction. In this study, we investigated whether the expression of PLPP/CIN is altered following LTP induction, and whether Tat‐PLPP/CIN transduction affects LTP induction in the rat dentate gyrus (DG). PLPP/CIN immunoreactivity was markedly decreased in dentate granule cells after the induction of LTP. Tat‐PLPP/CIN transduction (20 and 200 μg/kg) decreased the efficiency of high frequency stimulus‐induced potentiation of populations spike amplitude as compared to saline or Tat‐protein‐treated animals. The PLPP/CIN protein level showed an inverse correlation with phosphorylated ADF/cofilin levels and F‐actin content. These findings suggest that PLPP/CIN‐mediated actin dynamics may play an important role in the changes of morphological properties (dendritic spine reorganization) of the hippocampus in LTP. © 2009 Wiley‐Liss, Inc.