@article {737, title = {Lipid metabolic perturbation is an early-onset phenotype in adultmutants: amodel for lysosomal storage disorders. [Mass Spectrometry - Lipidomics]}, journal = {Mol Biol Cell}, volume = {28}, year = {2017}, month = {2017 Dec 15}, pages = {3728-3740}, abstract = {

Intracellular accumulation of lipids and swollen dysfunctional lysosomes are linked to several neurodegenerative diseases, including lysosomal storage disorders (LSD). Detailed characterization of lipid metabolic changes in relation to the onset and progression of neurodegeneration is currently missing. We systematically analyzed lipid perturbations inmutants, amodel of LSD-like neurodegeneration. Our results highlight an imbalance in brain ceramide and sphingosine in the early stages of neurodegeneration, preceding the accumulation of endomembranous structures, manifestation of altered behavior, and buildup of lipofuscin. Manipulating levels ofand altering these lipids inmutants allowed us to conclude that ceramide homeostasis is the driving force in disease progression and is integral tofunction in the adult nervous system. We identified 29 novel physical interaction partners of Spin and focused on the lipid carrier protein, Lipophorin (Lpp). A subset of Lpp and Spin colocalize in the brain and within organs specialized for lipid metabolism (fat bodies and oenocytes). Reduced Lpp protein was observed inmutant tissues. Finally, increased levels of lipid metabolites produced by oenocytes inmutants allude to a functional interaction between Spin and Lpp, underscoring the systemic nature of lipid perturbation in LSD.

}, keywords = {Animals, Carrier Proteins, Disease Models, Animal, Drosophila, Drosophila Proteins, Lipid Metabolism, Lipids, Lipoproteins, Lysosomal Storage Diseases, Lysosomes, Membrane Proteins, Mutation, Nervous System, Neurodegenerative Diseases, Phenotype}, issn = {1939-4586}, doi = {10.1091/mbc.E16-09-0674}, author = {Hebbar, Sarita and Khandelwal, Avinash and Jayashree, R and Hindle, Samantha J and Chiang, Yin Ning and Yew, Joanne Y and Sweeney, Sean T and Schwudke, Dominik} } @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} } @article {713, title = {Active remodeling of cortical actin regulates spatiotemporal organization of cell surface molecules.}, journal = {Cell}, volume = {149}, year = {2012}, month = {2012 Jun 08}, pages = {1353-67}, abstract = {

Many lipid-tethered proteins and glycolipids exist as monomers and nanoclusters on the surface of living cells. The spatial distribution and dynamics of formation and breakup of nanoclusters does not reflect thermal and chemical equilibrium and is controlled by active remodeling of the underlying cortical actin. We propose a model for nanoclustering based on active hydrodynamics, wherein cell surface molecules bound to dynamic actin are actively driven to form transient clusters. This consistently explains all of our experimental observations. Using FCS and TIRF microscopy, we provide evidence for the existence of short, dynamic, polymerizing actin filaments at the cortex, a key assumption of the theoretical framework. Our theory predicts that lipid-anchored proteins that interact with dynamic actin must exhibit anomalous concentration fluctuations, and a cell membrane protein capable of binding directly to actin can form nanoclusters. These we confirm experimentally, providing an active mechanism for molecular organization and its spatiotemporal regulation on the plasma membrane.

}, keywords = {Actins, Animals, Cell Line, Tumor, Cell Membrane, CHO Cells, Cricetinae, Cytoskeleton, Humans, Membrane Proteins, Models, Biological, Spectrometry, Fluorescence}, issn = {1097-4172}, doi = {10.1016/j.cell.2012.05.008}, author = {Gowrishankar, Kripa and Ghosh, Subhasri and Saha, Suvrajit and C, Rumamol and Mayor, Satyajit and Rao, Madan} } @article {483, title = {Inositol 1,4,5-trisphosphate receptor and dSTIM function in Drosophila insulin-producing neurons regulates systemic intracellular calcium homeostasis and flight. [Drosophila facility]}, journal = {J Neurosci}, volume = {30}, year = {2010}, month = {2010 Jan 27}, pages = {1301-13}, abstract = {

Calcium (Ca(2+)) signaling is known to regulate the development, maintenance and modulation of activity in neuronal circuits that underlie organismal behavior. In Drosophila, intracellular Ca(2+) signaling by the inositol 1,4,5-trisphosphate receptor and the store-operated channel (dOrai) regulates the formation and function of neuronal circuits that control flight. Here, we show that restoring InsP(3)R activity in insulin-producing neurons of flightless InsP(3)R mutants (itpr) during pupal development can rescue systemic flight ability. Expression of the store operated Ca(2+) entry (SOCE) regulator dSTIM in insulin-producing neurons also suppresses compromised flight ability of InsP(3)R mutants suggesting that SOCE can compensate for impaired InsP(3)R function. Despite restricted expression of wild-type InsP(3)R and dSTIM in insulin-producing neurons, a global restoration of SOCE and store Ca(2+) is observed in primary neuronal cultures from the itpr mutant. These results suggest that restoring InsP(3)R-mediated Ca(2+) release and SOCE in a limited subset of neuromodulatory cells can influence systemic behaviors such as flight by regulating intracellular Ca(2+) homeostasis in a large population of neurons through a non-cell-autonomous mechanism.

}, keywords = {Animals, Calcium, Calcium Signaling, Cell Membrane, Cells, Cultured, Central Nervous System, Drosophila, Drosophila Proteins, Flight, Animal, Homeostasis, Inositol 1,4,5-Trisphosphate Receptors, Insulin, Intracellular Fluid, Membrane Proteins, Mutation, Neural Pathways, Neurons, Pupa, Stromal Interaction Molecule 1}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.3668-09.2010}, author = {Agrawal, Neha and Venkiteswaran, Gayatri and Sadaf, Sufia and Padmanabhan, Nisha and Banerjee, Santanu and Hasan, Gaiti} }