TY - JOUR
T1 - Toll-like receptor 9–dependent AMPKa activation occurs via TAK1 and contributes to RhoA/ROCK signaling and actin polymerization in vascular smooth muscle cells
AU - McCarthy, Cameron G.
AU - Wenceslau, Camilla F.
AU - Ogbi, Safia
AU - Szasz, Theodora
AU - Clinton Webb, R.
N1 - Publisher Copyright:
Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.
PY - 2018/4
Y1 - 2018/4
N2 - Traditionally, Toll-like receptor 9 (TLR9) signals through an MyD88-dependent cascade that results in proinflammatory gene transcription. Recently, it was reported that TLR9 also participates in a stress tolerance signaling cascade in nonimmune cells. In this noncanonical pathway, TLR9 binds to and inhibits sarcoplasmic/endoplasmic reticulum Ca 21 -ATPase 2 (SERCA2), modulating intracellular calcium handling, and subsequently resulting in the activation of 59-AMP–activated protein kinase a (AMPKa). We have previously reported that TLR9 causes increased contraction in isolated arteries; however, the mechanisms underlying this vascular dysfunction need to be further clarified. Therefore, we hypothesized that noncanonical TLR9 signaling was also present in vascular smooth muscle cells (VSMCs) and that it mediates enhanced contractile responses through SERCA2 inhibition. To test these hypotheses, aortic microsomes, aortic VSMCs, and isolated arteries from male Sprague-Dawley rats were incubated with vehicle or TLR9 agonist (ODN2395). Despite clear AMPKa activation after treatment with ODN2395, SERCA2 activity was unaffected. Alternatively, ODN2395 caused the phosphorylation of AMPKa via transforming growth factor b–activated kinase 1 (TAK1), a kinase involved in TLR9 inflammatory signaling. Downstream, we hypothesized that that TLR9 activation of AMPKa may be important in mediating actin cytoskeleton reorganization. ODN2395 significantly increased the filamentous-to-globular actin ratio, as well as indices of RhoA /Rho-associated protein kinase (ROCK) activation, with the latter being prevented by AMPKa inhibition. In conclusion, AMPKa phosphorylation after TLR9 activation in VSMCs appears to be an extension of traditional inflammatory signaling via TAK1, as opposed to SERCA2 inhibition and the noncanonical pathway. Nonetheless, TLR9-AMPKa signaling can mediate VSMC function via RhoA /ROCK activation and actin polymerization.
AB - Traditionally, Toll-like receptor 9 (TLR9) signals through an MyD88-dependent cascade that results in proinflammatory gene transcription. Recently, it was reported that TLR9 also participates in a stress tolerance signaling cascade in nonimmune cells. In this noncanonical pathway, TLR9 binds to and inhibits sarcoplasmic/endoplasmic reticulum Ca 21 -ATPase 2 (SERCA2), modulating intracellular calcium handling, and subsequently resulting in the activation of 59-AMP–activated protein kinase a (AMPKa). We have previously reported that TLR9 causes increased contraction in isolated arteries; however, the mechanisms underlying this vascular dysfunction need to be further clarified. Therefore, we hypothesized that noncanonical TLR9 signaling was also present in vascular smooth muscle cells (VSMCs) and that it mediates enhanced contractile responses through SERCA2 inhibition. To test these hypotheses, aortic microsomes, aortic VSMCs, and isolated arteries from male Sprague-Dawley rats were incubated with vehicle or TLR9 agonist (ODN2395). Despite clear AMPKa activation after treatment with ODN2395, SERCA2 activity was unaffected. Alternatively, ODN2395 caused the phosphorylation of AMPKa via transforming growth factor b–activated kinase 1 (TAK1), a kinase involved in TLR9 inflammatory signaling. Downstream, we hypothesized that that TLR9 activation of AMPKa may be important in mediating actin cytoskeleton reorganization. ODN2395 significantly increased the filamentous-to-globular actin ratio, as well as indices of RhoA /Rho-associated protein kinase (ROCK) activation, with the latter being prevented by AMPKa inhibition. In conclusion, AMPKa phosphorylation after TLR9 activation in VSMCs appears to be an extension of traditional inflammatory signaling via TAK1, as opposed to SERCA2 inhibition and the noncanonical pathway. Nonetheless, TLR9-AMPKa signaling can mediate VSMC function via RhoA /ROCK activation and actin polymerization.
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U2 - 10.1124/jpet.117.245746
DO - 10.1124/jpet.117.245746
M3 - Article
C2 - 29348267
AN - SCOPUS:85043282975
SN - 0022-3565
VL - 365
SP - 60
EP - 71
JO - Journal of Pharmacology and Experimental Therapeutics
JF - Journal of Pharmacology and Experimental Therapeutics
IS - 1
ER -