The RISK of ROCK

How Protein Depletion Balances Thrombosis and Bleeding Risk in the Context of Platelet's Activatory and Negative Signaling

Platelets are small cell fragments that play a crucial role in hemostasis, requiring fast response times and fine signaling pathway regulation. For this regulation, platelets require a balance between two pathway types: the activatory and negative signaling pathways. Activatory signaling mediators are positive responses that enhance stimuli initiated by a receptor in the platelet membrane. Negative signaling regulates and controls the responses downstream of the same receptors to roll back or even avoid spontaneous thrombotic events. Several blood-related pathologies can be observed when these processes are unregulated, such as massive bleeding in activatory signaling inhibition or thrombotic events for negative signaling inhibition. The study of each protein and metabolite in isolation does not help to understand the role of the protein or how it can be contrasted; however, understanding the balance between active and negative signaling could help develop effective therapies to prevent thrombotic events and bleeding disorders.

The combination approach with Rho-kinase inhibition and mechanical circulatory support in myocardial ischemia-reperfusion injury: Rho-kinase inhibition and ventricular unloading

Background

It remains unclear whether the Rho-kinase (ROCK) inhibition in combination with mechanical circulatory support (MCS) had a synergic protective effect on myocardial ischemia (MI)/reperfusion injury in therapeutic strategies for acute myocardial infarction (AMI). We report the results of an approach using a rat model consisting of a miniaturized cardiopulmonary bypass (CPB) and AMI.

Methods

A total of 25 male Wistar rats were randomized into 5 groups: (1) Sham: a suture was passed under the left anterior descending artery (LAD) creating no MI. A vehicle solution (0.9% saline) was injected intraperitoneally. (2) Myocardial ischemia (MI) + vehicle (MI + V): LAD was ligated for 30 min and reperfused for 120 min, followed by administration of vehicle solution. (3) MI + fasudil (MI + F): the work sequence of group 2, but the selective ROCK inhibitor fasudil (10 mg/kg) was administered instead. (4) MI + V + CPB: CPB was initiated 15 min after the ligation of the LAD to the end of the reperfusion, in addition to the work sequence in group 2. (5) In the MI + F + CPB group, the work sequence of group 4, but with fasudil administration (10 mg/kg).

Results

Measurements of cardiac function through conductance catheter indicated that the drop of + dP/dt after reperfusion was moderately limited in MI + F + CPB (vs. MI + V, dP/dt p = 0.22). The preload recruitable stroke work was moderately improved in the MI + F + CPB (p = 0.23) compared with the corresponding control animals (MI + V). Phosphorylated protein kinase B expression in the MI + V + CPB and MI + F + CPB was higher than that in MI + V (p = 0.33).

Conclusion

Therefore, fasudil administration with MCS resulted in a moderately better left ventricular performance.

Computational systematic selectivity of the Fasalog inhibitors between ROCK-I and ROCK-II kinase isoforms in Alzheimer's disease

Human Rho-associated coiled-coil forming kinase (ROCK) is a class of essential neurokinases that consists of two structurally conserved isoforms ROCK-I and ROCK-II; they have been revealed to play distinct roles in the pathogenesis of Alzheimer's disease (AD) and other neurological disorders. Selective targeting of the two kinase isoforms with small-molecule inhibitors is a great challenge due to the surprisingly high homology in kinase domain (92 %) and the full identity in kinase active site (100 %). Here, we describe a computational protocol to systematically profile the selectivity of Fasudil and its 25 analogs (termed as Fasalogs) between the two kinase isoforms. It is suggested that the substitution of Fasudil's 1,4-diazepane moiety with rigid ring such as Ripasudil and Dimehtylfasudil would render the resulting inhibitors of ROCK-II over ROCK-I (II-o-I) selectivity, while the substitution with long, flexible group such as H-89 and BDBM92607 tends to have I-o-II selectivity. Structural analysis reveals that the inhibitor affinity is not only determined by the identical active site, but also contributed from the non-identical first and second shells of the site as well as other non-conserved kinase regions, which can indirectly influence the active site and inhibitor binding through allosteric effect. A further kinase assay basically confirms the computational findings, which also exhibits a good consistence with theoretical selectivity over 10 tested samples (Rp = 0.89). In particular, the Fasalog compounds Dimehtylfasudil and H-89 are identified as II-o-I and I-o-II selective inhibitors. They can be considered as promising lead molecular entities to develop new specific ROCK isoform-selective Fasalog inhibitors.

An Update on the Association of Protein Kinases with Cardiovascular Diseases

Background:

Protein kinases are the enzymes involved in phosphorylation of different proteins which leads to functional changes in those proteins. They belong to serine-threonine kinases family and are classified into the AGC (Protein kinase A/ Protein kinase G/ Protein kinase C) families of protein and Rho-associated kinase protein (ROCK). The AGC family of kinases are involved in G-protein stimuli, muscle contraction, platelet biology and lipid signaling. On the other hand, ROCK regulates actin cytoskeleton which is involved in the development of stress fibres. Inflammation is the main signal in all ROCK-mediated disease. It triggers the cascade of a reaction involving various proinflammatory cytokine molecules.

Methods:

Two ROCK isoforms are found in mammals and invertebrates. The first isoforms are present mainly in the kidney, lung, spleen, liver, and testis. The second one is mainly distributed in the brain and heart.

Results:

ROCK proteins are ubiquitously present in all tissues and are involved in many ailments that include hypertension, stroke, atherosclerosis, pulmonary hypertension, vasospasm, ischemia-reperfusion injury and heart failure. Several ROCK inhibitors have shown positive results in the treatment of various disease including cardiovascular diseases.

Conclusion:

ROCK inhibitors, fasudil and Y27632, have been reported for significant efficiency in dropping vascular smooth muscle cell hyper-contraction, vascular inflammatory cell recruitment, cardiac remodelling and endothelial dysfunction which highlight ROCK role in cardiovascular diseases.

Ischemic Postconditioning After Routine Thrombus Aspiration During Primary Percutaneous Coronary Intervention: Rationale and Design of the POstconditioning Rotterdam Trial

BACKGROUND

Whether ischemic postconditioning (IPOC) immediately after routine thrombus aspiration (TA) reduces infarct size (IS) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI) has not been established.

STUDY DESIGN

The POstconditioning Rotterdam Trial (PORT) is a dual-center, prospective, open-label, randomized trial with blinded endpoint evaluation enrolling 72 subjects with first-time STEMI, and an occluded infarct-related artery (IRA) without collaterals undergoing PPCI. Subjects are randomized 1:1 to a strategy of IPOC immediately after TA followed by stenting of the IRA or to conventional percutaneous coronary intervention (PCI), including TA followed by stenting of the IRA (controls). Cardiac magnetic resonance imaging (MRI) is performed at 3-5 days after STEMI and at 3 months. The primary endpoint is IS at 3 months measured by delayed enhancement MRI. Other secondary endpoints include MRI-derived microvascular obstruction (MVO), left ventricular ejection fraction, myocardial salvage index, enzymatic IS, ST-segment resolution, myocardial blush grade, microcirculatory resistance, inflammation markers, and clinical events through 3-month follow-up.

CONCLUSIONS

PORT is testing the hypothesis that adding IPOC (against lethal reperfusion injury) to TA (against distal embolization and MVO) is cardioprotective and reduces ultimate IS in STEMI patients undergoing PPCI (Dutch Trial Register identifier: NTR4040). © 2015 Wiley Periodicals, Inc.

High‑dose fasudil preconditioning and postconditioning attenuate myocardial ischemia‑reperfusion injury in hypercholesterolemic rats

Fasudil may induce preconditioning and postconditioning against myocardial ischemia‑reperfusion injury in normal rats, however, their effectivenesses in hypercholesterolemia remains to be determined. The study aimed to investigate whether fasudil induces preconditioning and postconditioning in hypercholesterolemic rats and to determine the roles of the phosphoinositol 3‑kinase (PI3K)/Akt/endothelial nitric oxide synthase (eNOS) pathway and mitochondrial KATP (m‑KATP) channels in this process. Isolated rat hearts underwent 30 min global ischemia and 120 min reperfusion. Low‑ (1 mg/kg) or high‑dose (10 mg/kg) fasudil was administered 15 min prior to ischemia and at the initial onset of reperfusion. 5‑Hydroxydecanoic acid (5HD), an m‑KATP channel blocker, at 10 mg/kg was administered 5 min prior to reperfusion. Myocardial infarct size was estimated by 2,3,5‑triphenyltetrazolium chloride (TTC) staining and lactate dehydrogenase (LDH) and creatine kinase‑MB (CK‑MB) were analyzed from coronary effluents. Phosphorylation of Akt and eNOS was measured by immunoblotting. High‑dose fasudil‑induced preconditioning and postconditioning significantly reduced infarct size and the release of LDH and CK‑MB and increased the phosphorylation of Akt and eNOS compared with the control group, whereas low‑dose fasudil did not exert these beneficial effects. In addition, the cardioprotection of high‑dose fasudil‑induced preconditioning and postconditioning are blocked by 5HD. Low‑dose fasudil‑induced preconditioning and postconditioning are abrogated by hypercholesterolemia, while high‑dose fasudil restores the cardioprotection, which is involved in upregulation of the PI3K/Akt/eNOS pathway and inducing the opening of the m‑KATP channel.

RhoA/Rho-kinase and vascular diseases: what is the link?

RhoA/Rho-kinase pathway plays an important role in many pathological conditions. RhoA participates in the regulation of smooth muscle tone and activates many downstream kinases. The best characterized are the serine/threonine kinase isoforms (Rho-kinase or ROCK), ROCKα/ROCK2 and ROCKβ/ROCK1. ROCK is necessary for diverse functions such as local blood flow, arterial/pulmonary blood pressure, airway resistance and intestinal peristalsis. ROCK activation permits actin/myosin interactions and smooth muscle cells contraction by maintaining the activity of myosin light-chain kinase, independently of the free cytosolic calcium level. The sensitization of smooth muscle myofilaments to calcium has been implicated in many pathological states, such as hypertension, diabetes, heart attack, stroke, pulmonary hypertension, erectile dysfunction, and cancer. The focus of this review is on the involvement of RhoA/Rho-kinase in diseases. We will briefly describe the ROCK isoforms and the role of RhoA/Rho-kinase in the vasculature, before exploring the most recent findings regarding this pathway and various diseases.

Rescue treatment with a Rho-kinase inhibitor normalizes right ventricular function and reverses remodeling in juvenile rats with chronic pulmonary hypertension

Chronic pulmonary hypertension in infancy and childhood is characterized by a fixed and progressive increase in pulmonary arterial pressure and resistance, pulmonary arterial remodeling, and right ventricular hypertrophy and systolic dysfunction. These abnormalities are replicated in neonatal rats chronically exposed to hypoxia from birth in which increased activity of Rho-kinase (ROCK) is critical to injury, as evidenced by preventive effects of ROCK inhibitors. Our objective in the present study was to examine the reversing effects of a late or rescue approach to treatment with a ROCK inhibitor on the pulmonary and cardiac manifestations of established chronic hypoxic pulmonary hypertension. Rat pups were exposed to air or hypoxia (13% O(2)) from postnatal day 1 and were treated with Y-27632 (15 mg/kg) or saline vehicle by twice daily subcutaneous injection commencing on day 14, for up to 7 days. Treatment with Y-27632 significantly attenuated right ventricular hypertrophy, reversed arterial wall remodeling, and completely normalized right ventricular systolic function in hypoxia-exposed animals. Reversal of arterial wall remodeling was accompanied by increased apoptosis and attenuated content of endothelin (ET)-1 and ET(A) receptors. Treatment of primary cultured juvenile rat pulmonary artery smooth muscle cells with Y-27632 attenuated serum-stimulated ROCK activity and proliferation and increased apoptosis. Smooth muscle apoptosis was also induced by short interfering RNA-mediated knockdown of ROCK-II, but not of ROCK-I. We conclude that sustained rescue treatment with a ROCK inhibitor reversed both the hemodynamic and structural abnormalities of chronic hypoxic pulmonary hypertension in juvenile rats and normalized right ventricular systolic function. Attenuated expression and activity of ET-1 and its A-type receptor on pulmonary arterial smooth muscle was a likely contributor to the stimulatory effects of ROCK inhibition on apoptosis. In addition, our data suggest that ROCK-II may be dominant in enhancing survival of pulmonary arterial smooth muscle.

Radiosynthesis of N-[(11)C]-methyl-hydroxyfasudil as a new potential PET radiotracer for rho-kinases (ROCKs)

N-[(11)C]-methyl-hydroxyfasudil was synthesized as a new potential radiotracer for rho-kinases (ROCKs) via a two-step one-pot radiosynthesis. The first step was the methylation of the precursor N-Boc-hydroxyfasudil-sodium salt/benzo-15-crown-5 complex with [(11)C]methyl iodide. The second step involved deprotection of the tert-butoxycarbonyl protecting group. The radiochemical and chemical purities of N-[(11)C]-methyl-hydroxyfasudil were >95% and specific radioactivity was 1565-2565mCi/mumol at the end of the synthesis.

Rho-kinase-dependent F-actin rearrangement is involved in the inhibition of PI3-kinase/Akt during ischemia-reperfusion-induced endothelial cell apoptosis

Activation of cytoskeleton regulator Rho-kinase during ischemia-reperfusion (I/R) plays a major role in I/R injury and apoptosis. Since Rho-kinase is a negative regulator of the pro-survival phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway, we hypothesized that inhibition of Rho-kinase can prevent I/R-induced endothelial cell apoptosis by maintaining PI3-kinase/Akt activity and that protective effects of Rho-kinase inhibition are facilitated by prevention of F-actin rearrangement. Human umbilical vein endothelial cells were subjected to 1 h of simulated ischemia and 1 or 24 h of simulated reperfusion after treatment with Rho-kinase inhibitor Y-27632, PI3-kinase inhibitor wortmannin, F-actin depolymerizers cytochalasinD and latrunculinA and F-actin stabilizer jasplakinolide. Intracellular ATP levels decreased following I/R. Y-27632 treatment reduced I/R-induced apoptosis by 31% (P < 0.01) and maintained Akt activity. Both effects were blocked by co-treatment with wortmannin. Y-27632 treatment prevented the formation of F-actin bundles during I/R. Similar results were observed with cytochalasinD treatment. In contrast, latrunculinA and jasplakinolide treatment did not prevent the formation of F-actin bundles during I/R and had no effect on I/R-induced apoptosis. Apoptosis and Akt activity were inversely correlated (R (2) = 0.68, P < 0.05). In conclusion, prevention of F-actin rearrangement by Rho-kinase inhibition or by cytochalasinD treatment attenuated I/R-induced endothelial cell apoptosis by maintaining PI3-kinase and Akt activity.