title: Ceramide kinase regulates phospholipase C and phosphatidylinositol 4, 5, bisphosphate in phototransduction.
abstract: Phosphoinositide-specific phospholipase C (PLC) is a central effector for many biological responses regulated by G-protein-coupled receptors including Drosophila phototransduction where light sensitive channels are activated downstream of NORPA, a PLCbeta homolog. Here we show that the sphingolipid biosynthetic enzyme, ceramide kinase, is a novel regulator of PLC signaling and photoreceptor homeostasis. A mutation in ceramide kinase specifically leads to proteolysis of NORPA, consequent loss of PLC activity, and failure in light signal transduction. The mutant photoreceptors also undergo activity-dependent degeneration. Furthermore, we show that a significant increase in ceramide, resulting from lack of ceramide kinase, perturbs the membrane microenvironment of phosphatidylinositol 4, 5, bisphosphate (PIP(2)), altering its distribution. Fluorescence image correlation spectroscopic studies on model membranes suggest that an increase in ceramide decreases clustering of PIP(2) and its partitioning into ordered membrane domains. Thus ceramide kinase-mediated maintenance of ceramide level is important for the local regulation of PIP(2) and PLC during phototransduction.
authors.affiliation: Program in Gene Function and Expression and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Ujjaini
authors.initials: U
authors.lastname: Dasgupta
authors.forename: Takeshi
authors.initials: T
authors.lastname: Bamba
authors.forename: Salvatore
authors.initials: S
authors.lastname: Chiantia
authors.forename: Pusha
authors.initials: P
authors.lastname: Karim
authors.forename: Ahmad N Abou
authors.initials: AN
authors.lastname: Tayoun
authors.forename: Ikuko
authors.initials: I
authors.lastname: Yonamine
authors.forename: Satinder S
authors.initials: SS
authors.lastname: Rawat
authors.forename: Raghavendra Pralhada
authors.initials: RP
authors.lastname: Rao
authors.forename: Kunio
authors.initials: K
authors.lastname: Nagashima
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Fukusaki
authors.forename: Vishwajeet
authors.initials: V
authors.lastname: Puri
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Dolph
authors.forename: Petra
authors.initials: P
authors.lastname: Schwille
authors.forename: Jairaj K
authors.initials: JK
authors.lastname: Acharya
authors.forename: Usha
authors.initials: U
authors.lastname: Acharya
mesh_terms: D000818:Animals; D002518:Ceramides / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000502:physiology*; D004596:Electroretinography; D006706:Homeostasis; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism; D008027:Light; D055537:Light Signal Transduction / Q000502:physiology*; D009154:Mutation; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D054799:Phospholipase C beta / Q000235:genetics / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism*
chemical_list: D002518:Ceramides; D029721:Drosophila Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D011993:Recombinant Fusion Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C066324:ceramide kinase; D010738:Type C Phospholipases; C468371:NorpA protein, Drosophila; D054799:Phospholipase C beta