title: PLD1 and ERK2 regulate cytosolic lipid droplet formation.
abstract: We have previously uncovered roles for phospholipase D (PLD) and an unknown cytosolic protein in the formation of cytosolic lipid droplets using a cell-free system. In this report, PLD1 has been identified as the relevant isoform, and extracellular signal-regulated kinase 2 (ERK2) as the cytosolic protein. Increased expression of PLD1 increased lipid droplet formation whereas knockdown of PLD1 using siRNA was inhibitory. A role for ERK2 in basal lipid droplet formation was revealed by overexpression or microinjection, and ablation by siRNA knockdown or pharmacological inhibition. Similar manipulations of other Map kinases such as ERK1, JNK1 or JNK2 and p38alpha or p38beta were without effect. Insulin stimulated the formation of lipid droplets and this stimulation was inhibited by knockdown of PLD1 (by siRNA) and by inhibition or knockdown (by siRNA) of ERK2. Inhibition of ERK2 eliminated the effect of PLD1 on lipid droplet formation without affecting PLD1 activity, suggesting that PLD1 functions upstream of ERK2. ERK2 increased the phosphorylation of dynein which increased the amount of the protein on ADRP-containing lipid droplets. Microinjection of antibodies to dynein strongly inhibited the formation of lipid droplets, demonstrating that dynein has a central role in this formation. Thus dynein is a possible target for ERK2.
authors.affiliation: Wallenberg Laboratory for Cardiovascular Research, Göteborg University, Sahlgrenska University Hospital, Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Andersson
authors.forename: Pontus
authors.initials: P
authors.lastname: Boström
authors.forename: Johanna
authors.initials: J
authors.lastname: Ericson
authors.forename: Mikael
authors.initials: M
authors.lastname: Rutberg
authors.forename: Björn
authors.initials: B
authors.lastname: Magnusson
authors.forename: Denis
authors.initials: D
authors.lastname: Marchesan
authors.forename: Michel
authors.initials: M
authors.lastname: Ruiz
authors.forename: Lennart
authors.initials: L
authors.lastname: Asp
authors.forename: Ping
authors.initials: P
authors.lastname: Huang
authors.forename: Michael A
authors.initials: MA
authors.lastname: Frohman
authors.forename: Jan
authors.initials: J
authors.lastname: Borén
authors.forename: Sven-Olof
authors.initials: SO
authors.lastname: Olofsson
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004398:Dyneins / Q000037:antagonists & inhibitors / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects; D008055:Lipids / Q000502:physiology*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D041681:NIH 3T3 Cells; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000494:pharmacology
chemical_list: D000906:Antibodies; D007328:Insulin; D008055:Lipids; D034741:RNA, Small Interfering; D019950:Mitogen-Activated Protein Kinase 1; C105606:phospholipase D2; D010739:Phospholipase D; C106801:phospholipase D1; D004398:Dyneins