Rhabdomere biogenesis in Drosophila photoreceptors is acutely sensitive to phosphatidic acid levels

Abstract

Phosphatidic acid (PA) is postulated to have both structural and signaling functions during membrane dynamics in animal cells. In this study, we show that before a critical time period during rhabdomere biogenesis in Drosophila melanogaster photoreceptors, elevated levels of PA disrupt membrane transport to the apical domain. Lipidomic analysis shows that this effect is associated with an increase in the abundance of a single, relatively minor molecular species of PA. These transport defects are dependent on the activation state of Arf1. Transport defects via PA generated by phospholipase D require the activity of type I phosphatidylinositol (PI) 4 phosphate 5 kinase, are phenocopied by knockdown of PI 4 kinase, and are associated with normal endoplasmic reticulum to Golgi transport. We propose that PA levels are critical for apical membrane transport events required for rhabdomere biogenesis.

PI(4,5)P2 regulates myoblast fusion through Arp2/3 regulator localization at the fusion site

“…We next asked whether the fusion arrest observed in the sequestration experiment was due to masking of PI(4,5)P2 for endogenous binding partners or if the defect was caused by lessening the amount of PI(4,5)P2 in the composition of the plasma membrane at the fusion site. A kinase-dead version of Sktl had been shown to lower PI(4,5)P2 production during photoreceptor biogenesis (Raghu et al, 2009) and during mouse phagocytosis (Fairn et al, 2009). We first examined the expression of wild-type Sktl::RFP in the mesoderm together with PH plcγ ::GFP, which combined did not affect fusion ( Fig.…”

Comparative Lipidomic Analysis of Mouse and Human Brain with Alzheimer Disease

“…Several studies focusing on defined families of lipids have made use of this technology to analyze lipid composition from AD brain tissue, showing changes in plasmalogen phosphatidylethanolamine (pPE) (14), sulfatide (Sulf) (15), ceramide (Cer), galactosylceramide (GalCer), cholesterol (16), and alkylacylglycerophosphocholine (17). Our own study has shown that a specific molecular species of phosphatidic acid (PA) previously linked to neurodegeneration in the fly (18) accumulates in the forebrain of old Swedish APP (swAPP) mice (11).…”

Drosophila PI4KIIIalpha is required in follicle cells for oocyte polarization and Hippo signaling

“…Four classes of PI4Ks have been identified in mammalian cells that localize to different cellular compartments and are likely to perform nonredundant functions (Balla and Balla, 2006). Three PI4K genes have been annotated in the fly genome: four wheel drive (fwd; PI4KIIIbeta) (Polevoy et al, 2009), CG2929 (PI4KIIalpha) (Raghu et al, 2009) and CG10260 (PI4KIIIalpha).…”