Heat shock augments myosin phosphatase target-subunit phosphorylation.
Our previous study demonstrated that heat shock augmented vascular contraction. In the present study, we hypothesized that heat shock augments myosin phosphatase target-subunit (MYPT1) phosphorylation resulting in augmented vascular contraction. Endothelium-denuded rat aortic rings were mounted in organ baths, exposed to heat shock (42 degrees C for 45 min), and subjected to contraction 4 h after the heat shock followed by Western blot analysis for MLC(20) (the 20 kDa light chains of myosin II) or MYPT1. The contractile responses in both control and heat shock-treated aorta were inhibited by Y27632, an inhibitor of Rho-kinase. The level of the MLC(20) and MYPT1(Thr855) phosphorylation in response to KCl was higher in heat shock-treated aorta than that in timed-control. The increased MYPT1(Thr855) phosphorylation was inhibited by Y27632 (1.0 microM) in parallel with inhibition of MLC(20) phosphorylation and vascular contraction. These results indicate that heat shock augments MYPT1 phosphorylation resulting in augmented vascular contraction.
Kim
Jee In
JI
Department of Pharmacology, Kyungpook National University School of Medicine, Daegu 700-422, Republic of Korea.
Jeon
Su Bun
SB
Baek
Inji
I
Seok
Young Mi
YM
Shin
Heung-Mook
HM
Kim
In Kyeom
IK
D000577:Amides / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D018869:Heat-Shock Response / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors; D008297:Male; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D018994:Myosin Light Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors; D009281:Naphthalenes / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D054645:Protein Phosphatase 1; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013912:Threonine / Q000378:metabolism; D054460:rho-Associated Kinases
D000577:Amides; D001381:Azepines; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D018994:Myosin Light Chains; D009281:Naphthalenes; D011725:Pyridines; C070571:ML 7; C108830:Y 27632; D013912:Threonine; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D010749:Phosphoprotein Phosphatases; C499850:Ppp1r12a protein, rat; D054645:Protein Phosphatase 1