This Article Full Text Full Text (PDF) Data Supplement All Versions of this Article: 24/3/464    most recent 01.ATV.0000116028.42230.4cv1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hirano, K. Articles by Kanaide, H. Search for Related Content PubMed PubMed Citation Articles by Hirano, K. Articles by Kanaide, H. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB CALCIUM COMPOUNDS CALCIUM, ELEMENTAL Related Collections Other Vascular biology

(Arteriosclerosis, Thrombosis, and Vascular Biology. 2004;24:464.)
© 2004 American Heart Association, Inc.

Vascular Biology

Transduction of the N-Terminal Fragments of MYPT1 Enhances Myofilament Ca²⁺ Sensitivity in an Intact Coronary Artery

Katsuya Hirano; Dmitry N. Derkach; Mayumi Hirano; Junji Nishimura; Shosuke Takahashi; Hideo Kanaide

From the Division of Molecular Cardiology, Research Institute of Angiocardiology (K.H., D.N.D., M.H., J.N., H.K.), the Department of Anesthesia and Critical Care Medicine (S.T.), and the Kyushu University COE Program on Lifestyle-Related Diseases (H.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.

Correspondence to Dr Hideo Kanaide, Professor, Division of Molecular Cardiology, Research Institute of Angiocardiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. E-mail kanaide{at}molcar.med.kyushu-u.ac.jp

Objective— The region of the 110 kDa regulatory subunit (MYPT1) of smooth muscle myosin phosphatase involved in the regulation of contraction was determined under physiological conditions.

Methods and Results— Using HIV Tat protein-mediated protein transduction, the N-terminal fragments of MYPT1 were introduced to the intact porcine coronary arterial strips. Pre-incubation with 3 µmol/L TAT-MYPT1^1–374, a construct containing the Tat peptide and the residues 1 to 374 of MYPT1, for 15 minutes augmented (2.4-fold) the subsequent contraction induced by adding 1.25 mmol/L of extracellular Ca²⁺ under 118 mmol/L K⁺ depolarization, with no augmentation of the [Ca²⁺]_i elevation. The deletion of the Tat peptide, MYPT1^1–374, abolished the augmenting effect. TAT-MYPT1^1–296 demonstrated a weaker but significant augmentation (1.7-fold). However, TAT-MYPT1^1–171, TAT-MYPT1^39–374, TAT-MYPT1^39–296, and TAT-MYPT1^297–374 had no augmenting activity. The myosin light chain phosphorylation level as a function of extracellular Ca²⁺ concentrations was shifted to the left in the strips pretreated with TAT-MYPT1^1–374 compared with the control.

Conclusions— Region 1 to 296 was the minimal region involved in the enhancement of contraction, and region 297 to 374 played a supplemental role. These results suggested that the interaction mainly between catalytic subunit and MYPT1 play a critical role in the regulation of the endogenous myosin phosphatase in intact smooth muscle.

Key Words: myosin • phosphatase • smooth muscle • contraction • protein transduction

This article has been cited by other articles:

				K. Hirano, N. Nomoto, M. Hirano, F. Momota, A. Hanada, and H. Kanaide Distinct Ca2+ Requirement for NO Production between Proteinase-Activated Receptor 1 and 4 (PAR1 and PAR4) in Vascular Endothelial Cells J. Pharmacol. Exp. Ther., August 1, 2007; 322(2): 668 - 677. [Abstract] [Full Text] [PDF]

				T. Yufu, K. Hirano, D. Bi, M. Hirano, J. Nishimura, Y. Iwamoto, and H. Kanaide Rac1 Regulation of Surface Expression of Protease-Activated Receptor-1 and Responsiveness to Thrombin in Vascular Smooth Muscle Cells Arterioscler Thromb Vasc Biol, July 1, 2005; 25(7): 1506 - 1511. [Abstract] [Full Text] [PDF]

				N. Shiga, K. Hirano, M. Hirano, J. Nishimura, H. Nawata, and H. Kanaide Long-Term Inhibition of RhoA Attenuates Vascular Contractility by Enhancing Endothelial NO Production in an Intact Rabbit Mesenteric Artery Circ. Res., May 13, 2005; 96(9): 1014 - 1021. [Abstract] [Full Text] [PDF]

				D. Bi, J. Nishimura, N. Niiro, K. Hirano, and H. Kanaide Contractile Properties of the Cultured Vascular Smooth Muscle Cells: The Crucial Role Played by RhoA in the Regulation of Contractility Circ. Res., April 29, 2005; 96(8): 890 - 897. [Abstract] [Full Text] [PDF]