title: Vascular smooth muscle migration and proliferation in response to lysophosphatidic acid (LPA) is mediated by LPA receptors coupling to Gq.
abstract: Many G protein-coupled receptors can couple to multiple G proteins to convey their intracellular signaling cascades. The receptors for lysophosphatidic acid (LPA) possess this ability. LPA receptors are important mediators of a wide variety of biological actions including cell migration, proliferation and survival which are processes that can all have a considerable impact on vascular smooth muscle (VSM) and blood vessels. To date, confirmation of G proteins involved has mostly relied on the inhibition of Gi-mediated signaling via pertussis toxin (PTx). We were interested in the specific involvement of LPA-Gq-mediated signaling therefore we isolated aorta VSM cells (VSMCs) from transgenic mice that express a peptide inhibitor of Gq, GqI, exclusively in VSM. We detected both LPA1 and LPA2 receptor expression in mouse VSM whereas LPA1 and LPA3 were expressed in rat VSM. SM22-GqI did not alter LPA-induced migration but it was sufficient to attenuate LPA-induced proliferation. GqI expression also attenuated LPA-induced ERK1/2 and Akt activation by 40-50%. To test the feasibility of this peptide as a potential therapeutic agent, we also generated adenovirus encoding the GqI. Transient expression of GqI was capable of inhibiting both LPA-induced migration and proliferation of VSMCs isolated from rat and mouse. Furthermore, ERK activation in response to LPA was also attenuated in VSMCs with Adv-GqI. Therefore, LPA receptors couple to Gq in VSMC and mediate migration and proliferation which may be mediated through activation of ERK1/2 and Akt. Our data also suggest that both chronic and transient expression of the GqI peptide is an effective strategy to lower Gq-mediated LPA signaling and may be a successful therapeutic strategy to combat diseases with enhanced VSM growth such as occurs following angioplasty or stent implantation.
authors.affiliation: Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA.
authors.forename: Jihee
authors.initials: J
authors.lastname: Kim
authors.forename: Janelle R
authors.initials: JR
authors.lastname: Keys
authors.forename: Andrea D
authors.initials: AD
authors.lastname: Eckhart
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002465:Cell Movement / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D008246:Lysophospholipids / Q000494:pharmacology*; D051379:Mice; D008822:Mice, Transgenic; D008840:Microfilament Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D049368:Receptors, Lysophosphatidic Acid / Q000235:genetics / Q000378:metabolism*
chemical_list: D008246:Lysophospholipids; D008840:Microfilament Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D049368:Receptors, Lysophosphatidic Acid; C051615:transgelin; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; C032881:lysophosphatidic acid