Signal Transduction Mechanisms Involved in Angiotensin-(1–7)-Stimulated Arachidonic Acid Release and Prostanoid Synthesis in Rabbit Aortic Smooth Muscle Cells1
- Mubarack M. Muthalif1,
- Ibrahim F. Benter2,
- Mohammad R. Uddin3,
- Jason L. Harper1 and
- Kafait U. Malik1
- 1Department of Pharmacology, College of Medicine, The University of Tennessee Center for Health Sciences, Memphis, Tennessee 38163 (M.M.M., J.L.H., K.U.M.), 2Southern College of Optometry Memphis, Tennessee (I.F.B.), and 3LeMoyne Owen College, Memphis, Tennessee (M.R.U.)
Abstract
This study investigated the signal transduction mechanisms of angiotensin-(1–7) [Ang-(1–7)]- and Ang II-stimulated arachidonic acid (AA) release for prostaglandin (PG) production in rabbit aortic vascular smooth muscle cells. Ang II and Ang-(1–7) enhanced AA release in cells prelabeled with [3H]AA. However, 6-keto-PGF1α synthesis produced by Ang II was much less than that caused by Ang-(1–7). In the presence of the lipoxygenase inhibitor baicalein, Ang II enhanced production of 6-keto-PGF1α to a greater degree than Ang-(1–7). Angiotensin type (AT)1 receptor antagonist DUP-753 inhibited only Ang II-induced [3H]AA release, whereas the AT2 receptor antagonist PD-123319 inhibited both Ang II- and Ang-(1–7)-induced [3H]AA release. Ang-(1–7) receptor antagonist d-Ala7-Ang-(1–7) inhibited the effect of Ang-(1–7), but not of Ang II. In cells transiently transfected with cytosolic phospholipase A2(cPLA2), mitogen-activated protein (MAP) kinase or Ca++-/calmodulin-dependent protein (CAM) kinase II antisense oligonucleotides, Ang-(1–7)- and Ang II-induced [3H]AA release was attenuated. The CaM kinase II inhibitor KN-93 and the MAP kinase kinase inhibitor PD-98059 attenuated both Ang-(1–7)- and Ang II-induced cPLA2 activity and [3H]AA release. Ang-(1–7) and Ang II also increased CaM kinase II and MAP kinase activities. Although KN-93 attenuated MAP kinase activity, PD-98059 did not affect CaM kinase II activity. Both Ang II and Ang-(1–7) caused translocation of cytosolic PLA2 to the nuclear envelope. These data show that Ang-(1–7) and Ang II stimulate AA release and prostacyclin synthesisvia activation of distinct types of AT receptors. Both peptides appear to stimulate CaM kinase II, which in turn,via MAP kinase activation, enhances cPLA2activity and release of AA for PG synthesis.
Footnotes
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Send reprint requests to: Kafait U. Malik, Ph.D., D.Sc., Professor, Department of Pharmacology, College of Medicine, The University of Tennessee, Memphis, Memphis, TN 38163.
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↵1 This work was supported by USPHS-NIH grant 19134 from the National Heart, Lung, and Blood Institute (K.U.M.), an American Heart Association Tennessee Affiliate New Investigator Award (I.F.B.), and a Center for Neuroscience Fellowship and an American Heart Association Tennessee Affiliate Postdoctoral Fellowship (M.M.M.).
- Abbreviations:
- AA
- arachidonic acid
- Ang
- angiotensin
- AT
- angiotensin type
- BSS
- balanced salt solution
- BSA
- bovine serum albumin
- CaM
- calmodulin
- CaM kinase
- Ca++-/CaM-dependent protein kinase
- cPLA2
- cytosolic PLA2
- DTT
- dithiothreitol
- EGTA
- ethyleneglycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid
- FBS
- fetal bovine serum
- FOX
- ferric oxidation of xylenol orange
- HBSS
- Hanks’ balanced salt solution
- HEPES
- N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid
- LO
- lipoxygenase
- MAFP
- methyl arachidonyl fluorophosphonate
- MAP kinase
- mitogen-activated protein kinase
- MEK
- MAP kinase kinase
- PG
- prostaglandin
- PK
- protein kinase
- PL
- phospholipase
- PMSF
- phenylmethylsulfonyl fluoride
- TBS
- tris-buffered saline
- TBST
- tris-buffered saline with Tween-20
- TRITC
- tetramethyl rhodamine B isothiocyanate
- VSMC
- vascular smooth muscle cells
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- Received June 30, 1997.
- Accepted September 29, 1997.
- The American Society for Pharmacology and Experimental Therapeutics
