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Effects of lipid kinase expression and cellular stimuli on phosphatidylinositol 5‐phosphate levels in mammalian cell lines
Author(s) -
Roberts Hilary F.,
Clarke Jonathan H.,
Letcher Andrew J.,
Irvine Robin F.,
Hinchliffe Katherine A.
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.04.027
Subject(s) - phosphatidylinositol , kinase , microbiology and biotechnology , inositol , inositol phosphate , chemistry , transfection , phospholipid , phosphatase , stimulation , biochemistry , lipid metabolism , biology , enzyme , receptor , endocrinology , membrane , gene
Phosphatidylinositol 5‐phosphate (PtdIns5P) is a relatively recently discovered inositol lipid whose metabolism and functions are not yet clearly understood. We have transfected cells with a number of enzymes that are potentially implicated in the synthesis or metabolism of PtdIns5P, or subjected cells to a variety of stimuli, and then measured cellular PtdIns5P levels by a specific mass assay. Stable or transient overexpression of Type IIα PtdInsP kinase, or transient overexpression of Type Iα or IIβ PtdInsP kinases caused no significant change in cellular PtdIns5P levels. Similarly, subjecting cells to oxidative stress or EGF stimulation had no significant effect on PtdIns5P, but stimulation of HeLa cells with a phosphoinositide‐specific PLC‐coupled agonist, histamine, caused a 40% decrease within 1 min. Our data question the degree to which inositide kinases regulate PtdIns5P levels in cells, and we discuss the possibility that a significant part of both the synthesis and removal of this lipid may be regulated by phosphatases and possibly phospholipases.