title: CaM kinase IIalpha mediates norepinephrine-induced translocation of cytosolic phospholipase A2 to the nuclear envelope.
abstract: Several growth factors, hormones and neurotransmitters, including norepinephrine, increase cellular calcium levels, promoting the translocation of cytosolic phospholipase A(2) to the nuclear envelope. This study was conducted to investigate the contributions of the calcium-binding protein calmodulin and of calcium-calmodulin-dependent protein kinase II to cytosolic phospholipase A(2) translocation to the nuclear envelope elicited by norepinephrine in rabbit aortic smooth-muscle cells. Norepinephrine caused cytosolic phospholipase A(2) accumulation around the nuclear envelope as determined from its immunofluorescence; cytosolic phospholipase A(2) translocation was blocked by inhibitors of calmodulin and calcium-calmodulin-dependent protein kinase II or calcium-calmodulin-dependent protein kinase IIalpha antisense oligonucleotide. Calmodulin and calcium-calmodulin-dependent protein kinase II inhibitors did not prevent cytosolic calcium increase but attenuated cytosolic phospholipase A(2) phosphorylation caused by norepinephrine or ionomycin. In vascular smooth-muscle cells reversibly permeabilized with beta-escin and treated with alkaline phosphatase, norepinephrine failed to cause cytosolic phospholipase A(2) phosphorylation and translocation to the nuclear envelope; these effects of norepinephrine were minimized by the phosphatase inhibitor okadaic acid. Recombinant cytosolic phospholipase A(2) phosphorylated by purified calcium-calmodulin-dependent protein kinase II, but not unphosphorylated or dephosphorylated cytosolic phospholipase A(2), introduced into permeabilized vascular smooth-muscle cells in the absence of calcium accumulated around the nuclear envelope. These data suggest that norepinephrine-induced translocation of cytosolic phospholipase A(2) to the nuclear envelope is mediated by its phosphorylation by calcium-calmodulin-dependent protein kinase II and that calcium alone is insufficient for cytosolic phospholipase A(2) translocation to the nuclear envelope in rabbit vascular smooth-muscle cells.
authors.affiliation: Department of Pharmacology and Centers for Connective Tissue Diseases and Vascular Biology, College of Medicine, The University of Tennessee Center for Health Sciences, Memphis, TN 38163, USA.
authors.forename: Soghra
authors.initials: S
authors.lastname: Fatima
authors.forename: Fariborz A
authors.initials: FA
authors.lastname: Yaghini
authors.forename: Aftab
authors.initials: A
authors.lastname: Ahmed
authors.forename: Zinat
authors.initials: Z
authors.lastname: Khandekar
authors.forename: Kafait U
authors.initials: KU
authors.lastname: Malik
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000469:Alkaline Phosphatase / Q000494:pharmacology; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004928:Escin / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D009685:Nuclear Envelope / Q000187:drug effects / Q000201:enzymology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010766:Phosphorylation / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits
chemical_list: D002147:Calmodulin; D004791:Enzyme Inhibitors; D016376:Oligonucleotides, Antisense; D015759:Ionomycin; D004928:Escin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010741:Phospholipases A; D054467:Phospholipases A2; D000469:Alkaline Phosphatase; D009638:Norepinephrine