title: Osmotic shock-dependent redistribution of diacylglycerol kinase η1 to non-ionic detergent-resistant membrane via pleckstrin homology and C1 domains.
abstract: Diacylglycerol kinase (DGK) participates in regulating the intracellular concentrations of two bioactive lipids, diacylglycerol and phosphatidic acid. DGKη1 is a type II isozyme that contains a pleckstrin homology (PH) domain and a pair of C1 domains at the N-terminus and separated catalytic domains (catalytic subdomain-a and b). We previously reported that DGKη1 expressed in COS-7 cells is translocated from the cytoplasm to punctate granules that partially include endosomes in response to stress stimuli such as osmotic shock. However, the biochemical properties of the stress-dependent behaviour of DGKη1 remain unknown. Here, we have found that DGKη1 is redistributed from the cytosol to the non-ionic detergent (Nonidet P-40)-resistant membrane (DRM) in response to osmotic shock. Our results strongly suggested that the Nonidet P-40 insolubility of DGKη1 is due to neither cytoskeleton localization nor lipid raft association, implying that DGKη1 is distributed to detergent-resistant membrane microdomains that have a low lipid-to-protein ratio. We revealed, using a series of DGKη1 deletion mutants, that the PH and C1 domains play a pivotal role in osmotic shock-dependent DRM redistribution, whereas catalytic subdomain-a negatively regulates the event.
authors.affiliation: Department of Chemistry, Graduate School of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Matsutomo
authors.forename: Takeshi
authors.initials: T
authors.lastname: Isozaki
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Sakai
authors.forename: Fumio
authors.initials: F
authors.lastname: Sakane
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000378:metabolism; D019852:Diacylglycerol Kinase / Q000737:chemistry* / Q000378:metabolism*; D015151:Immunoblotting; D008567:Membranes, Artificial; D008856:Microscopy, Fluorescence; D009997:Osmotic Pressure; D011145:Polyvinyls / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry; D005465:Fluorocarbon Polymers
chemical_list: D002784:Cholesterol; D019852:Diacylglycerol Kinase; D008567:Membranes, Artificial; D011145:Polyvinyls; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers