Ceramide kinase regulates phospholipase C and phosphatidylinositol 4, 5, bisphosphate in phototransduction
- Ujjaini Dasguptaa,b,
- Takeshi Bambac,1,
- Salvatore Chiantiad,1,
- Pusha Karima,b,
- Ahmad N. Abou Tayoune,
- Ikuko Yonaminea,b,
- Satinder S. Rawata,b,
- Raghavendra Pralhada Raof,
- Kunio Nagashimag,
- Eiichiro Fukusakic,
- Vishwajeet Purib,
- Patrick J. Dolphe,
- Petra Schwilled,
- Jairaj K. Acharyaf and
- Usha Acharyaa,b,2
- aProgram in Gene Function and Expression and
- bProgram in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605;
- cDepartment of Biotechnology, Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan;
- dBiotechnologisches Zentrum, Technical University of Dresden, 01187 Dresden, Germany;
- eDepartment of Biology, Dartmouth College, Hanover, NH 03755;
- fLaboratory of Cell and Developmental Signaling, National Cancer Institute, Frederick, MD 21702; and
- gEM Facility/Image Analysis Laboratory, SAIC, Frederick, MD 21702
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Communicated by Charles S. Zuker, University of California at San Diego, La Jolla, CA, September 25, 2009
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↵1T.B. and S.C. contributed equally to this work. (received for review June 16, 2009)
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 PLCβ 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 (PIP2), altering its distribution. Fluorescence image correlation spectroscopic studies on model membranes suggest that an increase in ceramide decreases clustering of PIP2 and its partitioning into ordered membrane domains. Thus ceramide kinase–mediated maintenance of ceramide level is important for the local regulation of PIP2 and PLC during phototransduction.
Footnotes
- 2To whom correspondence should be addressed. E-mail: usha.acharya{at}umassmed.edu
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Author contributions: U.D., T.B., S.C., P.S., J.K.A., and U.A. designed research; U.D., T.B., S.C., P.K., A.N.A.T., I.Y., S.S.R., R.P.R., K.N. J.K.A., and U.A. performed research; T.B., S.C., A.N.A.T., E.F., P.J.D., P.S., J.K.A., and U.A. analyzed data; and U.D., S.C., and U.A. wrote the paper.
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The authors declare no conflict of interest.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0911028106/DCSupplemental.
