The effects of inhibiting myosin light chain kinase on contraction and calcium signalling in human and rat myometrium

Longbottom, E. Rebecca; Luckas, Murray; Kupittayanant, Sajeera; Badrick, Ellena; Shmigol, T; Wray, Susan

doi:10.1007/s004240000305

Cited by 36 publications

(25 citation statements)

References 28 publications

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“…1), resulting in a significant increase in diastolic diameter. Similar results have been reported in studies (29,36,48) on the effects of the MLCK inhibitor on arteriolar, gastrointestinal, and uterine smooth muscle, suggesting that the tonic contraction of the lymphatic muscle may share some contractile regulatory mechanisms with smooth muscle from other organs.…”

Section: Discussionsupporting

confidence: 87%

Inhibition of myosin light chain phosphorylation decreases rat mesenteric lymphatic contractile activity

Wang¹,

Nepiyushchikh²,

Zawieja³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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Based on the well-established finding that the phosphorylation of myosin light chain 20 (MLC20) plays an essential role in blood vessel smooth muscle contraction, we investigated if phosphorylated MLC20 (pMLC20) would modulate the tonic and/or phasic contractions of lymphatic muscle. The effects of ML-7, a MLC kinase inhibitor (1-10 M), were tested on the contractile parameters of isolated and cannulated rat mesenteric lymphatics during their responses to the known modulators, pressure (1-5 cmH2O) and substance P (SP; 10 Ϫ7 M). Immunohistochemical and Western blot analyses of pMLC20 were also performed on isolated lymphatics. The results showed that 1) increasing pressure decreased both the lymphatic tonic contraction strength and pMLC20-to-MLC20 ratio; 2) SP increased both the tonic contraction strength and phosphorylation of MLC20; 3) ML-7 decreased both the lymphatic tonic contraction strength and pMLC20-to-MLC20 ratio; and 4) the increase in lymphatic phasic contraction frequency in response to increasing pressure was diminished by ML-7; however, the phasic contraction amplitude was not significantly altered by ML-7 either in the absence or presence of SP. These data provide the first evidence that tonic contraction strength and phasic contraction amplitude of the lymphatics can be differentially regulated, whereby the increase in MLC20 phosphorylation produces an activation in the tonic contraction without significant changes in the phasic contraction amplitude. Thus, tonic contraction of rat mesenteric lymphatics appears to be MLC kinase dependent. ML-7; lymphatic contraction; tonic contraction; phasic contraction THE LYMPHATIC SYSTEM plays essential roles by returning the protein-rich interstitial fluid to the blood circulation for fluid homeostasis, transporting lipids and lipid-soluble vitamins absorbed from the intestines to the circulation for nutrition, and distributing immune cells to the lymph nodes for defense against diseases. All of these vital functions rely on the contractile activities of the muscle cells residing in the lymphatic vessel wall. The muscular lymphatic vessels are composed of many basic structural and functional units called lymphangions, which are capable of exhibiting intrinsic contractile activities to propel lymph flow through the network of the lymphatic vessels. Although the classical influence of pressure and flow on lymphatic contractility has been well documented (14 -16, 24, 31, 37, 38, 51), the molecular mechanisms regulating the contractile activities of the lymphatic muscle are not well understood.Cardiac muscles and most vascular smooth muscles (VSMs) exercise their physiological functions by phasic and tonic contractions, respectively, whereas lymphatic muscle accomplishes its functions using both tonic and phasic contractions. In general, an increase in the intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) is the primary mechanism that initiates muscle contraction, a mechanism shared by striated muscles and VSMs. In striated muscle, Ca 2ϩ binding to troponin C in...

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Section: Discussionsupporting

confidence: 87%

Inhibition of myosin light chain phosphorylation decreases rat mesenteric lymphatic contractile activity

Wang¹,

Nepiyushchikh²,

Zawieja³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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“…The effect of wortmannin (4 µM), an inhibitor of myosin light chain kinase, on force (top traces) and intracellular Ca 2+ transients (bottom traces), arising either spontaneously (A) or stimulated by oxytocin (B, 10 nM). Taken from Longbottom et al (2000).…”

Section: Contractionmentioning

confidence: 99%

The Physiological Basis of Uterine Contractility: A Short Review

Wray

Kupittayanant

Shmygol

et al. 2001

Experimental Physiology

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119

118

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In this review we discuss our current understanding of the cellular basis of uterine contractility, highlighting those areas requiring further study. It is clear that the basic processes of excitation‐contraction coupling lie within the myometrial cell, and that these may be modified by agonists. Pacemaker acitivity, however, remains a mystery. The contribution of extracellular calcium entry to contraction is shown to be vital, whilst the role of the sarcoplasmic reticulum remains controversial. Much current experimental focus is on pathways controlling and regulating contraction, and we discuss sensitisation mechanisms and question their role in intact uterine preparations.

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“…The essential need for MYLK-mediated phosphorylation of MYL has been demonstrated in human myometrium [3], although MYL phosphorylation-independent pathways may be complementary in other species [12]. Our study has revealed phasic changes in the phosphorylation of 18 proteins (4 with multiple phosphorylation sites), with the greatest change in phosphorylation on serine 1760 of MYLK.…”

Section: Discussionmentioning

confidence: 57%

“…Phosphorylation of MYL during myometrial contractions has been demonstrated [1,2], and pharmacological inhibition of MYLK in human myometrium shows that MYLK-induced phosphorylation of MYL is essential for force generation [3]. We have previously demonstrated that the regulatory subunit of myosin phosphatase (MYPT) can be reversibly phosphorylated at an inhibitory site (thr853) during phasic myometrial contractions [2], which contributes to oxytocin-induced Ca 2+ -sensitisation.…”

Section: Introductionmentioning

confidence: 99%

Phosphorylation of proteins during human myometrial contractions: A phosphoproteomic approach

Hudson

Bernal

2017

Biochemical and Biophysical Research Communications

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms . Other yet unknown phosphorylation or de-phosphorylation events may contribute to myometrial contraction and relaxation. In this study we have performed a global phosphoproteomic analysis of human myometrial tissue using tandem mass tagging to detect changes in the phosphorylation status of individual myometrial proteins during spontaneous and oxytocin-driven phasic contractions. We were able to detect 22 individual phosphopeptides whose relative ratio changed (fold > 2 or < 0.5) in response to spontaneous or oxytocin-stimulated contraction.The most significant changes in phosphorylation were to MYLK on serine 1760, a site associated with reductions in calmodulin binding and subsequent kinase activity.Phosphorylated MYLK (ser1760) increased significantly during spontaneous (9.83 ± 3.27 fold, P < 0.05) and oxytocin -induced (18.56 ± 8.18 fold, P < 0.01) contractions and we were able to validate these data using immunoblotting. Pathway analysis suggested additional proteins involved in calcium signalling, cGMP-PRKG signalling, adrenergic signalling and oxytocin signalling were also phosphorylated during contractions. This study demonstrates that a global phosphoproteomic analysis of myometrial tissue is a sensitive approach to detect changes in the phosphorylation of proteins during myometrial contractions, and provides a platform for further validation of these changes and for identification of their functional significance.

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The effects of inhibiting myosin light chain kinase on contraction and calcium signalling in human and rat myometrium

Cited by 36 publications

References 28 publications

Inhibition of myosin light chain phosphorylation decreases rat mesenteric lymphatic contractile activity

Inhibition of myosin light chain phosphorylation decreases rat mesenteric lymphatic contractile activity

The Physiological Basis of Uterine Contractility: A Short Review

Phosphorylation of proteins during human myometrial contractions: A phosphoproteomic approach

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