Intact actin filaments are required for cytosolic phospholipase A 2 translocation but not for its activation by norepinephrine in vascular smooth muscle cells

Soghra Fatima, Fariborz A. Yaghini, Zoran Pavicevic, Shailaja Kalyankrishna, Nauzanene Jafari, Elizabeth Luong, Anne Estes, Kafait Malik

Research output: Contribution to journalArticle

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Abstract

Cytosolic phospholipase A2 (cPLA2) is activated and translocated to the nuclear envelope by various vasoactive agents, including norepinephrine (NE), and releases arachidonic acid (AA) from tissue phospholipids. We previously demonstrated that NE-induced cPLA2 translocation to the nuclear envelope is mediated via its phosphorylation by calcium/calmodulin-dependent kinase-II in rabbit vascular smooth muscle cells (VSMCs). Cytoskeletal structures actin and microtubule filaments have been implicated in the trafficking of proteins to various cellular sites. This study was conducted to investigate the contribution of actin and microtubule filaments to cPLA2 translocation to the nuclear envelope and its activation by NE in rabbit VSMCs. NE (10 μM) caused cPLA2 translocation to the nuclear envelope as determined by immunofluorescence. Cytochalasin D (CD; 0.5 μM) and latrunculin A (LA; 0.5 μM) that disrupted actin filaments, blocked cPLA2 translocation elicited by NE. On the other hand, disruption of microtubule filaments by 10 μM colchicine did not block NE-induced cPLA 2 translocation to the nuclear envelope. CD and LA did not inhibit NE-induced increase in cytosolic calcium and cPLA2 activity, determined from the hydrolysis of L-1-[14C]arachidonyl phosphatidylcholine and release of AA. Coimmunoprecipitation studies showed an association of actin with cPLA2, which was not altered by CD or LA. Far-Western analysis showed that cPLA2 interacts directly with actin. Our data suggest that NE-induced cPLA2 translocation to the nuclear envelope requires an intact actin but not microtubule filaments and that cPLA2 phosphorylation and activation and AA release are independent of its translocation to the nuclear envelope in rabbit VSMCs.

Original languageEnglish (US)
Pages (from-to)1017-1026
Number of pages10
JournalJournal of Pharmacology and Experimental Therapeutics
Volume313
Issue number3
DOIs
StatePublished - Jun 1 2005

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Cytosolic Phospholipases A2
Phospholipases A
Actin Cytoskeleton
Vascular Smooth Muscle
Smooth Muscle Myocytes
Norepinephrine
Nuclear Envelope
Microtubules
Arachidonic Acid
Actins
Rabbits
Phosphorylation
Calcium
Cytochalasin D
Calcium-Calmodulin-Dependent Protein Kinases
Colchicine
Protein Transport
Phosphatidylcholines
Fluorescent Antibody Technique
Phospholipids

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Pharmacology

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Intact actin filaments are required for cytosolic phospholipase A 2 translocation but not for its activation by norepinephrine in vascular smooth muscle cells. / Fatima, Soghra; Yaghini, Fariborz A.; Pavicevic, Zoran; Kalyankrishna, Shailaja; Jafari, Nauzanene; Luong, Elizabeth; Estes, Anne; Malik, Kafait.

In: Journal of Pharmacology and Experimental Therapeutics, Vol. 313, No. 3, 01.06.2005, p. 1017-1026.

Research output: Contribution to journalArticle

Fatima, Soghra ; Yaghini, Fariborz A. ; Pavicevic, Zoran ; Kalyankrishna, Shailaja ; Jafari, Nauzanene ; Luong, Elizabeth ; Estes, Anne ; Malik, Kafait. / Intact actin filaments are required for cytosolic phospholipase A 2 translocation but not for its activation by norepinephrine in vascular smooth muscle cells. In: Journal of Pharmacology and Experimental Therapeutics. 2005 ; Vol. 313, No. 3. pp. 1017-1026.
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AU - Yaghini, Fariborz A.

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AU - Kalyankrishna, Shailaja

AU - Jafari, Nauzanene

AU - Luong, Elizabeth

AU - Estes, Anne

AU - Malik, Kafait

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AB - Cytosolic phospholipase A2 (cPLA2) is activated and translocated to the nuclear envelope by various vasoactive agents, including norepinephrine (NE), and releases arachidonic acid (AA) from tissue phospholipids. We previously demonstrated that NE-induced cPLA2 translocation to the nuclear envelope is mediated via its phosphorylation by calcium/calmodulin-dependent kinase-II in rabbit vascular smooth muscle cells (VSMCs). Cytoskeletal structures actin and microtubule filaments have been implicated in the trafficking of proteins to various cellular sites. This study was conducted to investigate the contribution of actin and microtubule filaments to cPLA2 translocation to the nuclear envelope and its activation by NE in rabbit VSMCs. NE (10 μM) caused cPLA2 translocation to the nuclear envelope as determined by immunofluorescence. Cytochalasin D (CD; 0.5 μM) and latrunculin A (LA; 0.5 μM) that disrupted actin filaments, blocked cPLA2 translocation elicited by NE. On the other hand, disruption of microtubule filaments by 10 μM colchicine did not block NE-induced cPLA 2 translocation to the nuclear envelope. CD and LA did not inhibit NE-induced increase in cytosolic calcium and cPLA2 activity, determined from the hydrolysis of L-1-[14C]arachidonyl phosphatidylcholine and release of AA. Coimmunoprecipitation studies showed an association of actin with cPLA2, which was not altered by CD or LA. Far-Western analysis showed that cPLA2 interacts directly with actin. Our data suggest that NE-induced cPLA2 translocation to the nuclear envelope requires an intact actin but not microtubule filaments and that cPLA2 phosphorylation and activation and AA release are independent of its translocation to the nuclear envelope in rabbit VSMCs.

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