scholarly journals A Small Molecule Pyrazolo[3,4-d]Pyrimidinone Inhibitor of Zipper-Interacting Protein Kinase Suppresses Calcium Sensitization of Vascular Smooth Muscle

2015 ◽  
Vol 89 (1) ◽  
pp. 105-117 ◽  
Author(s):  
Justin A. MacDonald ◽  
Cindy Sutherland ◽  
David A. Carlson ◽  
Sabreena Bhaidani ◽  
Abdulhameed Al-Ghabkari ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Vascular Smooth Muscle ◽  
Small Molecule ◽  
Interacting Protein ◽  
Calcium Sensitization ◽  
Zipper Interacting Protein Kinase

Ca2+-independent contraction of longitudinal ileal smooth muscle is potentiated by a zipper-interacting protein kinase pseudosubstrate peptide

2009 ◽  
Vol 297 (2) ◽  
pp. G361-G370 ◽  
Author(s):  
Eikichi Ihara ◽  
Lori Moffat ◽  
Meredith A. Borman ◽  
Jennifer E. Amon ◽  
Michael P. Walsh ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Conformational Changes ◽  
Kinase Inhibitor ◽  
Smooth Muscles ◽  
Dominant Negative ◽  
Myosin Phosphatase ◽  
Interacting Protein ◽  
Zipper Interacting Protein Kinase

As a regulator of smooth muscle contraction, zipper-interacting protein kinase (ZIPK) can directly phosphorylate the myosin regulatory light chains (LC20) and produce contractile force. Synthetic peptides (SM-1 and AV25) derived from the autoinhibitory region of smooth muscle myosin light chain kinase can inhibit ZIPK activity in vitro. Paradoxically, treatment of Triton-skinned ileal smooth muscle strips with AV25, but not SM-1, potentiated Ca2+-independent, microcystin- and ZIPK-induced contractions. The AV25-induced potentiation was limited to ileal and colonic smooth muscles and was not observed in rat caudal artery. Thus the potentiation of Ca2+-independent contractions by AV25 appeared to be mediated by a mechanism unique to intestinal smooth muscle. AV25 treatment elicited increased phosphorylation of LC20 (both Ser-19 and Thr-18) and myosin phosphatase-targeting subunit (MYPT1, inhibitory Thr-697 site), suggesting involvement of a Ca2+-independent LC20 kinase with coincident inhibition of myosin phosphatase. The phosphorylation of the inhibitor of myosin phosphatase, CPI-17, was not affected. The AV25-induced potentiation was abolished by pretreatment with staurosporine, a broad-specificity kinase inhibitor, but specific inhibitors of Rho-associated kinase, PKC, and MAPK pathways had no effect. When a dominant-negative ZIPK [kinase-dead ZIPK(1–320)-D161A] was added to skinned ileal smooth muscle, the potentiation of microcystin-induced contraction by AV25 was blocked. Furthermore, pretreatment of skinned ileal muscle with SM-1 abolished AV25-induced potentiation. We conclude, therefore, that, even though AV25 is an in vitro inhibitor of ZIPK, activation of the ZIPK pathway occurs following application of AV25 to permeabilized ileal smooth muscle. Finally, we propose a mechanism whereby conformational changes in the pseudosubstrate region of ZIPK permit augmentation of ZIPK activity toward LC20 and MYPT1 in situ. AV25 or molecules based on its structure could be used in therapeutic situations to induce contractility in diseases of the gastrointestinal tract associated with hypomotility.

scholarly journals Chemical Genetics of Zipper-interacting Protein Kinase Reveal Myosin Light Chain as a Bona Fide Substrate in Permeabilized Arterial Smooth Muscle

2011 ◽  
Vol 286 (42) ◽  
pp. 36978-36991 ◽  
Author(s):  
Lori D. Moffat ◽  
Shannon B. A. Brown ◽  
Michael E. Grassie ◽  
Annegret Ulke-Lemée ◽  
Laura M. Williamson ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Chemical Genetics ◽  
Arterial Smooth Muscle ◽  
Interacting Protein ◽  
Zipper Interacting Protein Kinase ◽  
Bona Fide

Inhibition of zipper-interacting protein kinase function in smooth muscle by a myosin light chain kinase pseudosubstrate peptide

2007 ◽  
Vol 292 (5) ◽  
pp. C1951-C1959 ◽  
Author(s):  
Eikichi Ihara ◽  
Elena Edwards ◽  
Meredith A. Borman ◽  
David P. Wilson ◽  
Michael P. Walsh ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Muscle Tension ◽  
Independent Manner ◽  
Interacting Protein ◽  
Zipper Interacting Protein Kinase

As a regulator of smooth muscle contractility, zipper-interacting protein kinase (ZIPK) appears to phosphorylate the regulatory myosin light chain (RLC20), directly or indirectly, at Ser19 and Thr18 in a Ca2+-independent manner. The calmodulin-binding and autoinhibitory domain of myosin light chain kinase (MLCK) shares similarity to a sequence found in ZIPK. This similarity in sequence prompted an investigation of the SM1 peptide, which is derived from the autoinhibitory region of MLCK, as a potential inhibitor of ZIPK. In vitro studies showed that SM1 is a competitive inhibitor of a constitutively active 32-kDa form of ZIPK with an apparent Ki value of 3.4 μM. Experiments confirmed that the SM1 peptide is also active against full-length ZIPK. In addition, ZIPK autophosphorylation was reduced by SM1. ZIPK activity is independent of calmodulin; however, calmodulin suppressed the in vitro inhibitory potential of SM1, likely as a result of nonspecific binding of the peptide to calmodulin. Treatment of ileal smooth muscle with exogenous ZIPK was accompanied by an increase in RLC20 diphosphorylation, distinguishing between ZIPK [and integrin-linked kinase (ILK)] and MLCK actions. Administration of SM1 suppressed steady-state muscle tension developed by the addition of exogenous ZIPK to Triton-skinned rat ileal muscle strips with or without calmodulin depletion by trifluoperazine. The decrease in contractile force was associated with decreases in both RLC20 mono- and diphosphorylation. In summary, we present the SM1 peptide as a novel inhibitor of ZIPK. We also conclude that the SM1 peptide, which has no effect on ILK, can be used to distinguish between ZIPK and ILK effects in smooth muscle tissues.

Sign in / Sign up

Export Citation Format

Share Document