Immunohistochemical localization of phospholipase D2 in embryonic rat brain

Developmental levels of phospholipase D isozymes in the brain of developing rats

The developmental levels of phospholipase D (PLD) isozymes was examined in the cerebrum and hindbrain of the developing rat to better understand the involvement of PLD in brain development. Western blot analysis of PLD in the cerebrum showed that PLD1, a major PLD isoform in the brain, was detected weakly in the cerebrum at day 17 embryonic stage and its levels gradually increased until postnatal day 35 and remained unaltered thereafter. In the hindbrain, comprising the cerebellum and pons, the peak level of PLD1 was detected at 21 days postnatally and declined progressively thereafter. The level of PLD2 in both the cerebrum and hindbrain was minimal compared to that of PLD1. Based on immunohistochemistry, PLD was detected in some neurons and glial cells in the cerebrum. In the hindbrain, PLD was found in some Purkinje cells and some cells of the molecular layer, as well as glial cells, consistent with the results obtained from Western blot analysis. These findings suggest that PLD may differentially play a role in the course of early development of the brain, with special reference to the cerebrum and hindbrain, in rats.

Lipid second messengers and related enzymes in vertebrate rod outer segments

Rod outer segments (ROSs) are specialized light-sensitive organelles in vertebrate photoreceptor cells. Lipids in ROS are of considerable importance, not only in providing an adequate environment for efficient phototransduction, but also in originating the second messengers involved in signal transduction. ROSs have the ability to adapt the sensitivity and speed of their responses to ever-changing conditions of ambient illumination. A major contributor to this adaptation is the light-driven translocation of key signaling proteins into and out of ROS. The present review shows how generation of the second lipid messengers from phosphatidylcholine, phosphatidic acid, and diacylglycerol is modulated by the different illumination states in the vertebrate retina. Findings suggest that the light-induced translocation of phototransduction proteins influences the enzymatic activities of phospholipase D, lipid phosphate phosphatase, diacylglyceride lipase, and diacylglyceride kinase, all of which are responsible for the generation of the second messenger molecules.

ETOH inhibits embryonic neural stem/precursor cell proliferation via PLD signaling

While a mother's excessive alcohol consumption during pregnancy is known to have adverse effects on fetal neural development, little is known about the underlying mechanism of these effects. In order to investigate these mechanisms, we investigated the toxic effect of ethanol (ETOH) on neural stem/precursor cell (NSC) proliferation. In cultures of NSCs, phospholipase D (PLD) is activated following stimulation with epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2). Exposure of NSCs to ETOH suppresses cell proliferation, while it has no effect on cell death. Phosphatidic acid (PA), which is a signaling messenger produced by PLD, reverses ETOH inhibition of NSC proliferation. Blocking the PLD signal by 1-butanol suppresses the proliferation. ETOH-induced suppression of NSC proliferation and the protective effect of PA for ETOH-induced suppression are mediated through extracellular signal-regulated kinase signaling. These results indicate that exposure to ETOH impairs NSC proliferation by altering the PLD signaling pathway.