A Novel Phospholipase C, PLCη2, Is a Neuron-specific Isozyme*

By M. Nakahara, M. Shimozawa, Yoshikazu Nakamura, Y. Irino, M. Morita, Y. Kudo, K. Fukami. Journal of Biological Chemistry, 2005

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Twelve phospholipase C (PLC) isozymes have been cloned so far, and they are divided into six classes, β-, γ-, δ-, ϵ-, ζ-, and η-type, on the basis of structure and activation mechanisms. Here we report the identification of a novel PLC isozyme, PLCη2. PLCη2 is composed of conserved domains including pleckstrin homology, EF-hand, X and Y catalytic, and C2 domains and the isozyme-specific C-terminal region. PLCη2 consists of 1164 amino acids with a molecular mass of 125 kDa. The PLC activity of PLCη2 was more sensitive to calcium concentration than the PLC activity of the PLCδ-type enzyme, which is thought to be the most calcium-sensitive PLC. Immunofluorescence analysis showed that PLCη2 was localized predominantly to the plasma membrane at resting state via the pleckstrin homology domain. This observation was supported by Western blot analysis of cytosol and membrane fractions. In addition, expression of PLCη2 was detected after birth and showed a restricted distribution in the brain; it was particularly abundant in the hippocampus, cerebral cortex, and olfactory bulb. The pattern was similar to that of the neuronal marker microtubule-associated protein 2 by Western blot. Furthermore, in situ hybridization showed positive signals for PLCη2 in pyramidal cells of the hippocampus. Finally, we found that PLCη2 was expressed abundantly in neuron-containing primary culture but not in astrocyte-enriched culture. These results indicate that PLCη2 is a neuron-specific isozyme that may be important for the formation and/or maintenance of the neuronal network in the postnatal brain.

Subfields: Cellular and Molecular Neuroscience, Molecular Biology

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