Synaptic PRG-1 Modulates Excitatory Transmission via Lipid Phosphate-Mediated Signaling

Abstract

SUMMARY Plasticity related gene-1 (PRG-1) is a brain-specific membrane protein related to lipid phosphate phosphatases, which acts in the hippocampus specifically at the excitatory synapse terminating on glutamatergic neurons. Deletion of prg-1 in mice leads to epileptic seizures and augmentation of EPSCs, but not IPSCs. In utero electroporation of PRG-1 into deficient animals revealed that PRG-1 modulates excitation at the synaptic junction. Mutation of the extracellular domain of PRG-1 crucial for its interaction with lysophosphatidic acid (LPA) abolished the ability to prevent hyperexcitability. As LPA application in vitro induced hyperexcitability in wild-type but not in LPA2 receptor-deficient animals, and uptake of phospholipids is reduced in PRG-1-deficient neurons, we assessed PRG-1/LPA2 receptor-deficient animals, and found that the pathophysiology observed in the PRG-1-deficient mice was fully reverted. Thus, we propose PRG-1 as an important player in the modulatory control of hippocampal excitability dependent on presynaptic LPA2 receptor signaling.

PRG-1 transcriptional regulation independent from Nex1/Math2-mediated activation

“…Immunocytochemistry for parvalbumin and calretinin (Fig. 2a, b) confirmed no colocalization with interneurons, as described previously for PRG-1 [34]. This indicates that all necessary elements for neuronal subtype expression of prg-1 are present on the BAC sequence selected for transgene generation.…”

“…PRG-1 is involved in modulation of neuronal transmission via bioactive lipids, such as LPA acting via presynaptic LPA 2 receptors, which are controlled by PRG-1 from the postsynaptic side (specifically at the glutamatergic junction). According to recent data, this action may be mediated by PRG-1 by depleting the pool of bioactive lipids that act on the presynaptic LPA 2 receptors [34].…”

“…Linearized BAC-DNA was microinjected into zygotes of NMRIfoster mice at the Max Delbrück Centrum (Berlin, Germany). PRG-1 KO-mouse: Generation described in detail [34]. Nex1 KO-mouse was kindly provided by Nave [28].…”

“…Recently, analysis of PRG-1 null mouse models elucidated the modulatory role of the postsynaptically localized PRG-1 protein during excitatory synaptic transmission on glutamatergic neurons. This role of PRG-1 in neuronal transmission is thought to depend on an interaction of PRG-1 and lipid phosphates like LPA, acting through presynaptic LPA 2 -receptors [34]. In order to elucidate the peculiar expression profile of PRG-1 in neurons, we generated a reporter mouse model expressing YPF controlled by the native PRG-1 promoter and were able to show that 200-kb sequence enclosing the PRG-1 gene are effectual to confer cell type-specific expression.…”

C57BL/6-specific conditions for efficient in utero electroporation of the central nervous system

“…Different areas of the mouse brain can be manipulated by varying the position of the positive electrode (Kolk et al, 2011;Langevin et al, 2007;Navarro-Quiroga et al, 2007;Saito and Nakatsuji, 2001). The combination of in utero electroporation with transgenic mouse strains additionally enhances the number of possible applications for elucidating the molecular mechanisms of brain development and function (Trimbuch et al, 2009). In utero electroporation was primarily established in ICR/CD-1 outbred mice (Fukuchi-Shimogori and Grove, 2001;Saito and Nakatsuji, 2001;Tabata and Nakajima, 2001).…”