Phosphorylation of myosin light chain kinase from vascular smooth muscle by cAMP- and cGMP-dependent protein kinases

1985 ◽  
Vol 17 (9) ◽  
pp. 841-850 ◽  
Author(s):  
D HATHAWAY ◽  
M KONICKI ◽  
S COOLICAN
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Protein Kinases ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Dependent Protein ◽  
Camp And Cgmp

Regulation of vascular smooth muscle tone

1994 ◽  
Vol 72 (8) ◽  
pp. 919-936 ◽  
Author(s):  
Michael P. Walsh
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Contractile Response ◽  
Muscle Tone ◽  
Myosin Phosphorylation ◽  
Smooth Muscle Tone ◽  
Vascular Smooth Muscle Tone

Vascular smooth muscle tone is regulated primarily by the sarcoplasmic free Ca2+ concentration, which determines the level of myosin phosphorylation. Stimulation of the muscle results in an increase in free [Ca2+], whereupon Ca2+ binds to calmodulin, inducing a conformational change enabling calmodulin to interact with and activate myosin light chain kinase. The active Ca2+∙calmodulin∙myosin light chain kinase complex catalyses the phosphorylation of serine-19 of the two 20-kDa light chains of myosin; this triggers cross-bridge cycling and the development of force. Relaxation follows restoration of free [Ca2+] to the resting level, whereupon calmodulin dissociates from myosin light chain kinase, which is thereby inactivated, and myosin is dephosphorylated by myosin light chain phosphatase and remains detached from actin. Overwhelming evidence now exists in favour of the central role of myosin phosphorylation–dephosphorylation in smooth muscle contraction–relaxation. However, considerable evidence supports the existence of additional, secondary mechanisms that can modulate the contractile state of smooth muscle either by altering the Ca2+ sensitivity of the contractile response or otherwise modulating one of the molecular events occurring downstream of the Ca2+ signal, e.g., the interaction of phosphorylated myosin heads with actin. The interplay of several regulatory elements confers on the contractile response of vascular smooth muscle the high degree of flexibility and adaptability required for the effective regulation of blood pressure.Key words: calcium, myosin, protein kinases, protein phosphatases, signal transduction, regulation of contraction, caldesmon, calponin.

scholarly journals Polyamines inhibit phospholipid-sensitive and calmodulin-sensitive Ca2+-dependent protein kinases

1983 ◽  
Vol 213 (2) ◽  
pp. 281-288 ◽  
Author(s):  
D F Qi ◽  
R C Schatzman ◽  
G J Mazzei ◽  
R S Turner ◽  
R L Raynor ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Polymyxin B ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Endogenous Proteins

Effects of polyamines on various protein kinases were investigated. It was found that both phospholipid-sensitive Ca2+-dependent protein kinase and myosin light-chain kinase (a calmodulin-sensitive species of Ca2+-dependent protein kinase) were inhibited to different degrees by polyamines, with an approximate order of inhibitory potency of spermine = 1, 12-diaminododecane greater than spermidine = 1, 10-diaminodecane much greater than cadaverine = putrescine. Kinetic analysis revealed that spermine inhibited the phospholipid-sensitive enzyme non-competitively with respect to Ca2+ (Ki = 0.84 mM) and phosphatidylserine (Ki = 0.90 mM); it also inhibited myosin light-chain kinase non-competitively with respect to Ca2+ (Ki = 1.82 mM) and calmodulin (Ki = 2.73 mM). 1, 12-Diaminododecane, in comparison, inhibited the phospholipid-sensitive enzyme competitively with respect to Ca2+ (Ki = 0.45 mM) and phosphatidylserine (Ki = 0.50 mM); it also inhibited myosin light-chain kinase competitively with respect to calmodulin (Ki = 0.63 mM) but non-competitively with respect to Ca2+ (Ki = 1.49 mM). Moreover, spermine (0.5 mM) was found to inhibit markedly phosphatidylserine/Ca2+- and calmodulin/Ca2+-stimulated phosphorylation of endogenous proteins in rat brain particulate fraction. All the polyamines tested were practically without effect on cyclic AMP-dependent and cyclic GMP-dependent protein kinases. Polyarginine, like spermine, was found to be a more selective inhibitor of Ca2+-dependent protein kinases, whereas polyglutamate preferentially inhibited the cyclic nucleotide-dependent enzymes. The present results indicated that, in addition to certain lipophilic compounds (such as trifluoperazine, palmitoylcarnitine, adriamycin and naphthalenesulphonamide) and polypeptides with hydrophobic regions (such as melittin and polymyxin B) previously reported, polycationic compounds (exemplified by polyamines) could also inhibit the two classes of Ca2+-dependent protein kinases requiring either phospholipid or calmodulin as a cofactor. Because of the high cellular concentration (up to 10 mM) and the differential effects of polyamines, it is suggested that spermine, and to smaller extents spermidine and putrescine, may be involved in the regulation of certain Ca2+-dependent protein-phosphorylation systems in vivo.

Effect of calmodulin, Ca2+, and cAMP protein kinase on skinned tracheal smooth muscle

1984 ◽  
Vol 246 (3) ◽  
pp. C308-C314 ◽  
Author(s):  
M. P. Sparrow ◽  
G. Pfitzer ◽  
M. Gagelmann ◽  
J. C. Ruegg
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Progressive Increase ◽  
Response Curves ◽  
Tension Development ◽  
Regulation Of Contraction ◽  
Dependent Protein

The characteristics of contraction and relaxation of membrane skinned smooth muscle from guinea pig trachealis muscle are described. Micromolar Ca2+ elicited reproducible contractions in Mg-ATP salt solution at 20 degrees C. The speed of contraction was much faster at 30 and 37 degrees C, enabling cumulative concentration-response curves to be obtained. At these temperatures, a progressive increase in basal tension occurred in the absence of Ca2+. This tension was active and developed more rapidly at pH 6.7 than at pH 7.0. Calmodulin (0.1-10 microM) greatly increased the speed of contraction and lowered the threshold Ca2+ concentration ([Ca2+]) required to initiate contraction from 0.13 to 0.02 microM Ca2+. Trifluoperazine antagonized responses to Ca2+. Thiophosphorylation with adenosine 5'-O-(3-thiotriphosphate) produced maximum tension development, which was Ca2+-independent. This effect was reversible. The results are compatible with myosin-linked regulation of contraction in which a Ca2+ X calmodulin complex activates myosin light chain kinase to phosphorylate myosin. The catalytic subunit of cAMP-dependent protein kinase strongly inhibited tension development and slowly relaxed fibers contracted with threshold [Ca2+] consistent with an action via phosphorylation of myosin light chain kinase. This effect was extremely slow compared with the rate of relaxation by Ca2+ withdrawal or with relaxation of intact smooth muscle by beta-adrenergic agonists.

Cyclic nucleotide dependent relaxation in vascular smooth muscle

1994 ◽  
Vol 72 (11) ◽  
pp. 1380-1385 ◽  
Author(s):  
Nancy L. McDaniel ◽  
Christopher M. Rembold ◽  
Richard A. Murphy
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Light Chain ◽  
Cyclic Nucleotide ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Regulatory Light Chain ◽  
Myosin Phosphorylation ◽  
Cross Bridge ◽  
The Relationship

Although not without controversy, the mechanisms inducing contraction of vascular smooth muscle are relatively well defined. There is a stimulus-induced increase in myoplasmic [Ca2+] with activation of myosin light chain kinase by the Ca2+–calmodulin complex, phosphorylation of the 20-kDa regulatory light chain of myosin, with subsequent cross-bridge cycling and force development. Ca2+-dependent phosphorylation of the myosin regulatory light chain appears to be the primary mechanism responsible for regulating stress in vascular smooth muscle. The relationship between myoplasmic [Ca2+] and myosin phosphorylation (i.e., the calcium sensitivity of phosphorylation) is regulated. It is higher with agonist stimulation than in tissues depolarized with high potassium solutions or after skinning procedures. The relationship between myosin phosphorylation and stress appears to be invariant with physiologic stimulation. This suggests that cross-bridge phosphorylation normally determines contraction. The mechanisms of relaxation are less well defined. In the most simple scheme, reduction of myoplasmic [Ca2+] with a fall in myosin light chain kinase activity would suffice to account for dephosphorylation of the regulatory light chain and relaxation. However, other mechanisms have been implicated in cyclic nucleotide dependent relaxation in vascular and other smooth muscle tissues. The current hypotheses of the mechanism of cyclic nucleotide dependent relaxation in vascular smooth muscle are reviewed.Key words: calcium, cyclic adenosine 3′,5′-monophosphate, cyclic guanosine 3′,5′-monophosphate, myosin light chain phosphorylation, vasodilation.

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