Diacylglycerol kinase-θ is localized in the speckle domains of the nucleus

Giovanna Tabellini, Roberta Bortul, Spartaco Santi, Massimo Riccio, Giovanna Baldini, Alessandra Cappellini, Anna Maria Billi, Ronald Berezney, Alessandra Ruggeri, Lucio Cocco, Alberto M. Martelli

Research output: Contribution to journalArticle

Abstract

It is well established that the nucleus is endowed with enzymes that are involved in lipid-dependent signal transduction pathways. Diacylglycerol (DAG) is a fundamental lipid second messenger that is produced in the nucleus. Previous reports have shown that the nucleus contains diacylglycerol kinases (DGKs), i.e., the enzymes that, by converting DAG into phosphatidic acid (PA), terminate DAG-dependent events. Here, we show, by immunofluorescence staining and confocal analysis, that DGK-θ localizes mainly to the nucleus of various cell lines, such as MDA-MB-453, MCF-7, PC12, and HeLa. Nuclear DGK-θ co-localizes with phosphatidylinositol 4,5-bisphosphate (PIP2) in domains that correspond to nuclear speckles, as revealed by the use of an antibody to the splicing factor SC-35, a well-established marker for these structures. The spatial distribution of nuclear DGK-θ was dynamic in that it was affected by inhibition of mRNA transcription with α-amanitin. Immuno-electron microscopy analysis demonstrated that DGK-θ, PIP2, and phosphoinositide-specific phospholipase Cβ1 (PLCβ1) associated with electron-dense particles within the nucleus that correspond to interchromatin granule clusters. Cell fractionation experiments performed in MDA-MB-453, HeLa, and PC12 cells showed a preferential association of DGK-θ with the nucleus. Western blots demonstrated that DGK-θ was enriched in the nuclear matrix fraction prepared from MDA-MB-453 cells. Immunoprecipitation experiments with an antibody to PLCβ1 revealed in MDA-MB-453 cells an association between this enzyme and both DGK-θ and phosphatidylinositol phosphate kinase Iα (PIPKIα). Our findings strengthen the contention that speckles represent a crucial site for the nuclear-based inositol lipid cycle. We may speculate that nuclear speckle-located DGK-θ, on cell stimulation with an agonist, converts to PA the DAG derived from PLCβ1-dependent PIP2 hydrolysis.

Original languageEnglish
Pages (from-to)143-154
Number of pages12
JournalExperimental Cell Research
Volume287
Issue number1
DOIs
Publication statusPublished - Jul 1 2003

Fingerprint

Diacylglycerol Kinase
Diglycerides
Phosphatidic Acids
Phosphatidylinositols
Lipids
Enzymes
Amanitins
Cell Fractionation
Nuclear Matrix
Phosphatidylinositol Phosphates
Immunoelectron Microscopy
Antibodies
PC12 Cells
Second Messenger Systems
Inositol
HeLa Cells
Immunoprecipitation
Fluorescent Antibody Technique
Signal Transduction
Hydrolysis

Keywords

  • Diacylglycerol
  • Inositol lipid cycle
  • Nuclear domains
  • Nuclear matrix
  • Nucleus
  • Signal transduction

ASJC Scopus subject areas

  • Cell Biology

Cite this

Tabellini, G., Bortul, R., Santi, S., Riccio, M., Baldini, G., Cappellini, A., ... Martelli, A. M. (2003). Diacylglycerol kinase-θ is localized in the speckle domains of the nucleus. Experimental Cell Research, 287(1), 143-154. https://doi.org/10.1016/S0014-4827(03)00115-0

Diacylglycerol kinase-θ is localized in the speckle domains of the nucleus. / Tabellini, Giovanna; Bortul, Roberta; Santi, Spartaco; Riccio, Massimo; Baldini, Giovanna; Cappellini, Alessandra; Billi, Anna Maria; Berezney, Ronald; Ruggeri, Alessandra; Cocco, Lucio; Martelli, Alberto M.

In: Experimental Cell Research, Vol. 287, No. 1, 01.07.2003, p. 143-154.

Research output: Contribution to journalArticle

Tabellini, G, Bortul, R, Santi, S, Riccio, M, Baldini, G, Cappellini, A, Billi, AM, Berezney, R, Ruggeri, A, Cocco, L & Martelli, AM 2003, 'Diacylglycerol kinase-θ is localized in the speckle domains of the nucleus', Experimental Cell Research, vol. 287, no. 1, pp. 143-154. https://doi.org/10.1016/S0014-4827(03)00115-0
Tabellini G, Bortul R, Santi S, Riccio M, Baldini G, Cappellini A et al. Diacylglycerol kinase-θ is localized in the speckle domains of the nucleus. Experimental Cell Research. 2003 Jul 1;287(1):143-154. https://doi.org/10.1016/S0014-4827(03)00115-0
Tabellini, Giovanna ; Bortul, Roberta ; Santi, Spartaco ; Riccio, Massimo ; Baldini, Giovanna ; Cappellini, Alessandra ; Billi, Anna Maria ; Berezney, Ronald ; Ruggeri, Alessandra ; Cocco, Lucio ; Martelli, Alberto M. / Diacylglycerol kinase-θ is localized in the speckle domains of the nucleus. In: Experimental Cell Research. 2003 ; Vol. 287, No. 1. pp. 143-154.
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AU - Cappellini, Alessandra

AU - Billi, Anna Maria

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