PLPP/CIN Regulates Seizure Activity by the Differential Modulation of Calsenilin Binding to GluN1 and Kv4.2 in Mice

Abstract

Calsenilin (CSEN) binds to Kv4.2 (an A-type K+ channel) as well as N-methyl-D-aspartate receptor (NMDAR), and modulates their activities. However, the regulatory mechanisms for CSEN-binding to Kv4.2 or NMDAR remain elusive. Here, we demonstrate the novel role of pyridoxal-5′-phosphate phosphatase/chronophin (PLPP/CIN), one of the cofilin-mediated F-actin regulators, in the CSEN binding to Kv4.2 or GluN1 (an NMDAR subunit). PLPP/CIN dephosphorylated CSEN in competition with casein kinase 1, independent of cofilin dephosphorylation. As compared to wild-type mice, PLPP/CIN transgenic (PLPP/CINTg) mice showed the enhancement of Kv4.2–CSEN binding, but the reduction in CSEN–GluN1 binding. In addition, PLPP/CINTg mice exhibited the higher intensity (severity), duration and progression of seizures, but the longer latency of seizure on-set in response to kainic acid. PLPP/CIN knockout mice reversed these phenomena. Therefore, we suggest that PLPP/CIN-mediated CSEN dephosphorylation may play an important role in the functional coupling of NMDAR and Kv4.2, which regulates the neuronal excitability.

PLPP/CIN-mediated NEDD4-2 S448 dephosphorylation regulates neuronal excitability via GluA1 ubiquitination

“…Recently, we have reported that PLPP/CIN −/− mice show the shorter latency of seizure onset, but interrupt seizure progression in response to KA 30 . In contrast, spontaneous NEDD mutation in NEDD4-2 andi mice increases seizure susceptibility in response to KA 14 .…”

“…In contrast, spontaneous NEDD mutation in NEDD4-2 andi mice increases seizure susceptibility in response to KA 14 . Since 2h after KA injection is the suitable time point to compare the time of seizure onset, total EEG power and the changes in anatomical or biochemical profiles in PLPP/CIN Tg and PLPP/CIN −/− mice 30 , we investigated whether PLPP/CIN-mediated NEDD4-2 ubiquitination reciprocally regulates seizure activity 2 h after KA injection. Consistent with our previous report 30 , PLPP/CIN deletion reduced the latency of seizure onset, seizure intensity (severity), and seizure duration in response to KA ( p < 0.05 vs. WT mice, respectively; Fig.…”

“…Furthermore, PLPP/CIN deletion exhibits the lower intensity (severity) 29 , duration, and progression of seizures, but the shorter latency of seizure onset in response to KA. PLPP/CIN overexpression reverses these phenomena 30 . These novel properties of PLPP/CIN provide the possibility that interaction of PLPP/CIN with other biological molecules may modulate neuronal hyperexcitability independent of F-actin depolymerization.…”

PDI Knockdown Inhibits Seizure Activity in Acute Seizure and Chronic Epilepsy Rat Models via S-Nitrosylation-Independent Thiolation on NMDA Receptor

“…EEG signals were digitized and analyzed using LabChart Pro v7 (AD Instruments, Australia). Spectrograms were automatically calculated using a Hanning sliding window with 50% overlap ( Kim et al, 2016 , 2017b ).…”

“…The hippocampal tissues were lysed in radioimmune precipitation buffer (RIPA) with protease and phosphatase inhibitor cocktails (Roche Applied Sciences, United States) and 1 mM sodium orthovanadate. After calibration of total protein concentrations, and equal amounts of proteins were precipitated with the primary antibody and subsequent protein G sepharose at 4°C overnight ( Kim et al, 2017b ). Beads were collected, eluted in sample buffer and boiled at 95°C for 5 min.…”