@article {473, title = {A dPIP5K dependent pool of phosphatidylinositol 4,5 bisphosphate (PIP2) is required for G-protein coupled signal transduction in Drosophila photoreceptors.[Drosophila facility]}, journal = {PLoS Genet}, volume = {11}, year = {2015}, month = {2015 Jan}, pages = {e1004948}, abstract = {

Multiple PIP2 dependent molecular processes including receptor activated phospholipase C activity occur at the neuronal plasma membranes, yet levels of this lipid at the plasma membrane are remarkably stable. Although the existence of unique pools of PIP2 supporting these events has been proposed, the mechanism by which they are generated is unclear. In Drosophila photoreceptors, the hydrolysis of PIP2 by G-protein coupled phospholipase C activity is essential for sensory transduction of photons. We identify dPIP5K as an enzyme essential for PIP2 re-synthesis in photoreceptors. Loss of dPIP5K causes profound defects in the electrical response to light and light-induced PIP2 dynamics at the photoreceptor membrane. Overexpression of dPIP5K was able to accelerate the rate of PIP2 synthesis following light induced PIP2 depletion. Other PIP2 dependent processes such as endocytosis and cytoskeletal function were unaffected in photoreceptors lacking dPIP5K function. These results provide evidence for the existence of a unique dPIP5K dependent pool of PIP2 required for normal Drosophila phototransduction. Our results define the existence of multiple pools of PIP2 in photoreceptors generated by distinct lipid kinases and supporting specific molecular processes at neuronal membranes.

}, keywords = {Animals, Cell Membrane, Cytoskeleton, Drosophila, Drosophila melanogaster, Light Signal Transduction, Membrane Proteins, Ocular Physiological Phenomena, Phosphatidylinositol 4,5-Diphosphate, Phosphoinositide Phospholipase C, Phosphotransferases (Alcohol Group Acceptor), Photoreceptor Cells, Retina, Signal Transduction}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1004948}, author = {Chakrabarti, Purbani and Kolay, Sourav and Yadav, Shweta and Kumari, Kamalesh and Nair, Amit and Trivedi, Deepti and Raghu, Padinjat} } @article {472, title = {RDGBα, a PtdIns-PtdOH transfer protein, regulates G-protein-coupled PtdIns(4,5)P2 signalling during Drosophila phototransduction.[Drosophila Facility]}, journal = {J Cell Sci}, volume = {128}, year = {2015}, month = {2015 Sep 01}, pages = {3330-44}, abstract = {

Many membrane receptors activate phospholipase C (PLC) during signalling, triggering changes in the levels of several plasma membrane lipids including phosphatidylinositol (PtdIns), phosphatidic acid (PtdOH) and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. It is widely believed that exchange of lipids between the plasma membrane and endoplasmic reticulum (ER) is required to restore lipid homeostasis during PLC signalling, yet the mechanism remains unresolved. RDGBα (hereafter RDGB) is a multi-domain protein with a PtdIns transfer protein (PITP) domain (RDGB-PITPd). We find that, in vitro, the RDGB-PITPd binds and transfers both PtdOH and PtdIns. In Drosophila photoreceptors, which experience high rates of PLC activity, RDGB function is essential for phototransduction. We show that binding of PtdIns to RDGB-PITPd is essential for normal phototransduction; however, this property is insufficient to explain the in vivo function because another Drosophila PITP (encoded by vib) that also binds PtdIns cannot rescue the phenotypes of RDGB deletion. In RDGB mutants, PtdIns(4,5)P2 resynthesis at the plasma membrane following PLC activation is delayed and PtdOH levels elevate. Thus RDGB couples the turnover of both PtdIns and PtdOH, key lipid intermediates during G-protein-coupled PtdIns(4,5)P2 turnover.

}, keywords = {Animals, Drosophila melanogaster, Drosophila Proteins, Eye Proteins, Light Signal Transduction, Membrane Proteins, Phosphatidic Acids, Phosphatidylinositol 4,5-Diphosphate, Type C Phospholipases}, issn = {1477-9137}, doi = {10.1242/jcs.173476}, author = {Yadav, Shweta and Garner, Kathryn and Georgiev, Plamen and Li, Michelle and Gomez-Espinosa, Evelyn and Panda, Aniruddha and Mathre, Swarna and Okkenhaug, Hanneke and Cockcroft, Shamshad and Raghu, Padinjat} }