Group IVA phospholipase A2 is necessary for the biogenesis of lipid droplets.
Lipid droplets (LD) are organelles present in all cell types, consisting of a hydrophobic core of triacylglycerols and cholesteryl esters, surrounded by a monolayer of phospholipids and cholesterol. This work shows that LD biogenesis induced by serum, by long-chain fatty acids, or the combination of both in CHO-K1 cells was prevented by phospholipase A(2) inhibitors with a pharmacological profile consistent with the implication of group IVA cytosolic phospholipase A(2) (cPLA(2)alpha). Knocking down cPLA(2)alpha expression with short interfering RNA was similar to pharmacological inhibition in terms of enzyme activity and LD biogenesis. A Chinese hamster ovary cell clone stably expressing an enhanced green fluorescent protein-cPLA(2)alpha fusion protein (EGFP-cPLA(2)) displayed higher LD occurrence under basal conditions and upon LD induction. Induction of LD took place with concurrent phosphorylation of cPLA(2)alpha at Ser(505). Transfection of a S505A mutant cPLA(2)alpha showed that phosphorylation at Ser(505) is key for enzyme activity and LD formation. cPLA(2)alpha contribution to LD biogenesis was not because of the generation of arachidonic acid, nor was it related to neutral lipid synthesis. cPLA(2)alpha inhibition in cells induced to form LD resulted in the appearance of tubulo-vesicular profiles of the smooth endoplasmic reticulum, compatible with a role of cPLA(2)alpha in the formation of nascent LD from the endoplasmic reticulum.
Gubern
Albert
A
Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, E-08193 Barcelona.
Casas
Javier
J
Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, E-47003 Valladolid, Spain.
Barceló-Torns
Miquel
M
Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, E-08193 Barcelona.
Barneda
David
D
Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, E-08193 Barcelona.
de la Rosa
Xavier
X
Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, E-08193 Barcelona.
Masgrau
Roser
R
Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, E-08193 Barcelona.
Picatoste
Fernando
F
Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, E-08193 Barcelona.
Balsinde
Jesús
J
Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, E-47003 Valladolid, Spain.
Balboa
María A
MA
Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, E-47003 Valladolid, Spain.
Claro
Enrique
E
Institut de Neurociències and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, E-08193 Barcelona. Electronic address: enrique.claro@uab.es.
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D054513:Group IV Phospholipases A2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats
D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D054513:Group IV Phospholipases A2; C516389:PLA2G4A protein, human; C516391:Pla2g4a protein, rat