HA1077, a protein kinase inhibitor, inhibits calponin phosphorylation on Ser175 in porcine coronary artery

Calponin in non-muscle cells

Calponin is an actin filament-associated regulatory protein expressed in smooth muscle and non-muscle cells. Calponin is an inhibitor of the actin-activated myosin ATPase. Three isoforms of calponin have been found in the vertebrates. Whereas the role of calponin in regulating smooth muscle contractility has been extensively investigated, the function and regulation of calponin in non-muscle cells is much less understood. Based on recent progresses in the field, this review focuses on the studies of calponin in non-muscle cells, especially its regulation by cytoskeleton tension and function in cell motility. The ongoing research has demonstrated that calponin plays a regulatory role in non-muscle cell motility. Therefore, non-muscle calponin is an attractive target for the control of cell proliferation, migration and phagocytosis, and the treatment of cancer metastasis.

Effect of Fasudil Hydrochloride, a Protein Kinase Inhibitor, on Cerebral Vasospasm and Delayed Cerebral Ischemic Symptoms After Aneurysmal Subarachnoid Hemorrhage-Results of a Randomized Trial of Fasudil Hydrochloride Versus Nimodipine-

The efficacy and safety of fasudil hydrochloride, a novel protein kinase inhibitor, were evaluated for the treatment of cerebral vasospasm and associated cerebral ischemic symptoms in patients with ruptured cerebral aneurysm. This randomized open trial with nimodipine as the control included 72 patients who underwent subarachnoid hemorrhage surgery for ruptured cerebral aneurysm of Hunt and Hess grades I to IV. For 14 days following surgery, patients were administered either 30 mg of fasudil hydrochloride by intravenous injection over a period of 30 minutes three times a day or 1 mg/hr of nimodipine by continuous intravenous infusion. Fasudil hydrochloride and nimodipine both showed inhibitory effects on cerebral vasospasm. The incidence of symptomatic vasospasm was five of 33 patients in the fasudil group and nine of 32 patients in the nimodipine group. Good recovery evaluated by the Glasgow Outcome Scale was achieved by 23 of 33 patients in the fasudil group and 19 of 34 patients in the nimodipine group. Both drugs significantly improved consciousness levels and neurological deficits such as aphasia. However, fasudil hydrochloride improved motor disturbance more than nimodipine. Adverse reactions occurred in 13 of 37 patients receiving fasudil hydrochloride and 15 of 35 patients receiving nimodipine. There were no serious adverse events in the fasudil group. The results of this clinical trial indicate that fasudil hydrochloride is a safe and efficient agent for suppressing cerebral vasospasm after subarachnoid hemorrhage surgery for ruptured cerebral aneurysm.

Inhibition of protein kinase C-mediated contraction by Rho kinase inhibitor fasudil in rabbit aorta

Protein kinase C (PKC) activation by a phorbol ester increases myosin light chain (MLC(20)) phosphorylation through inhibition of MLC phosphatase (MLCP) and enhances contraction of vascular smooth muscle. We investigated whether Rho kinase, which is known to inhibit MLCP, is involved in the MLC(20) phosphorylation caused by a phorbol ester, 12-deoxyphorbol 13-isobutyrate (DPB), in rabbit aortas. DPB (1 microM) increased MLC(20) phosphorylation and tension. The Rho kinase inhibitor fasudil (10 microM) inhibited the DPB-induced contraction and decreased the MLC(20) phosphorylation at Ser19, a site phosphorylated by MLC kinase, although it did not affect the phosphorylation of total MLC(20). Rinsing a 65.4 mM KCl-contracted aorta with Ca(2+)-free, EGTA solution caused rapid dephosphorylation of MLC(20) and relaxation. When DPB was present in the rinsing solution, the MLC(20) dephosphorylation and the relaxation were inhibited. In this protocol, Ro31-8220 (10 microM), a PKC inhibitor, suppressed the phosphorylation of total MLC(20) and Ser19 induced by DPB. Fasudil also inhibited the Ser19 phosphorylation to a degree similar to Ro31-8220 and accelerated relaxation, which was less than the relaxation caused by Ro31-8220. The phospholipase A(2) inhibitor ONO-RS-082 (5 microM) inhibited the DPB-induced Ser19 phosphorylation but only transiently decreased the tension, suggesting the involvement of arachidonic acid in the phosphorylation and the existence of a MLC(20) phosphorylation-independent mechanism. When fasudil was combined with ONO-RS-082, fasudil exerted additional inhibition of the tension without further inhibition of the Ser19 phosphorylation. DPB phosphorylated the 130 kDa myosin binding subunit (MBS) of MLCP and fasudil inhibited the phosphorylation. These data suggest that the inhibition by fasudil of DPB-induced contraction and phosphorylation of MLC(20) at the MLC kinase-targeted site is a result of inhibition of Rho kinase. Thus, the PKC-dependent Ca(2+)-sensitization of vascular smooth muscle involves Rho kinase. A MLC(20) phosphorylation-independent mechanism is also involved in the Ca(2+)-sensitization.

Transforming Growth Factor-β1 Specifically Induce Proteins Involved in the Myofibroblast Contractile Apparatus

Transforming growth factor-beta(1) (TGF-beta(1)) induces alpha-smooth muscle actin (alpha-SMA) and collagen synthesis in fibroblast both in vivo and in vitro and plays a significant role in tissue repair and the development of fibrosis. During these processes the fibroblasts differentiate into activated fibroblasts (so called myofibroblasts), characterized by increased alpha-SMA expression. Because TGF-beta(1) is considered the main inducer of the myofibroblast phenotype and cytoskeletal changes accompany this differentiation, the main objective of this investigation was to study how TGF-beta(1) alters protein expression of cytoskeletal-associated proteins. Metabolic labeling of cell cultures by [(35)S]methionine, followed by protein separation on two-dimensional gel electrophoresis, displayed approximately 2500 proteins in the pI interval of 3-10. Treatment of TGF-beta(1) led to specific spot pattern changes that were identified by mass spectrometry and represent specific induction of several members of the contractile apparatus such as calgizzarin, cofilin, and profilin. These proteins have not previously been shown to be regulated by TGF-beta(1), and the functional role of these proteins is to participate in the depolymerization and stabilization of the microfilaments. These results show that TGF-beta(1) induces not only alpha-SMA but a whole set of actin-associated proteins that may contribute to the increased contractile properties of the myofibroblast. These proteins accompany the induced expression of alpha-SMA and may participate in the formation of stress fibers, cell contractility, and cell spreading characterizing the myofibroblasts phenotype.

Essential role of rho kinase in the Ca2+ sensitization of prostaglandin F(2alpha)-induced contraction of rabbit aortae

Inhibition of dephosphorylation of the 20 kDa myosin light chain (MLC(20)) is an important mechanism for the Ca(2+)-induced sensitization of vascular smooth muscle contraction. We investigated whether this mechanism operates in prostaglandin F(2alpha) (PGF(2alpha))-induced contraction of rabbit aortic smooth muscle and, if so, whether protein kinase C (PKC) or rho-associated kinase (rho kinase) contribute to the inhibition of dephosphorylation. In normal medium, PGF(2alpha) (10 microM) increased the phosphorylation of MLC(20) and developed tension. The rho-kinase inhibitors fasudil and hydroxyfasudil inhibited these changes, despite having no effect on a phorbol-ester-induced MLC(20) phosphorylation. After treatment with verapamil or chelation of external Ca(2+) with EGTA, PGF(2alpha) increased the MLC(20) phosphorylation and tension without an increase in [Ca(2+)](i), all of which were sensitive to fasudil and hydroxyfasudil. ML-9, a MLC kinase inhibitor, quickly reversed the KCl-induced MLC(20) phosphorylation and contraction to the resting level. However, fractions of PGF(2alpha)-induced contraction and MLC(20) phosphorylation were resistant to ML-9 but were sensitive to fasudil. Ro31-8220 (10 microM), a PKC inhibitor, did not affect the phosphorylation of MLC(20) and the tension caused by PGF(2alpha), thus excluding the possibility of the involvement of PKC in the PGF(2alpha)-induced MLC(20) phosphorylation. PGF(2alpha) increased phosphorylation at Thr654 of the myosin binding subunit (MBS) of myosin phosphatase, which is a target of rho kinase, and fasudil decreased the phosphorylation. These data suggest that the PGF(2alpha)-induced contraction is accompanied by the inhibition of MLC(20) dephosphorylation through rho kinase-induced MBS phosphorylation, leading to Ca(2+) sensitization of contraction. An actin-associated mechanism may also be involved in the PGF(2alpha)-induced sensitization.

Rho kinase inhibition partly weakens myogenic reactivity in rat small arteries by changing calcium sensitivity

The hypothesis that Rho kinase is involved in myogenic reactivity was investigated in pressurized rat tail small arteries using videomicroscopic diameter determination and calcium fluorimetry. The potent Rho kinase inhibitor Y-27632 reversibly increased vessel diameter at 80 mmHg without changing the intracellular calcium concentration ([Ca](i)) shifting the relationship between diameter change and [Ca](i) to higher calcium levels. Neither endothelium removal nor inhibition of neural transmission affected the Y-27632-induced effect. Y-27632 at 3 x 10(-6) mol/l attenuated the myogenic response in the pressure range from 10 to 120 mmHg, shifting the relationship between vessel tone and [Ca](i) to higher calcium levels. In addition, the Y-27632-induced shift of the relationship between vessel tone and [Ca](i) was larger at 80 than at 10 mmHg. These results suggest that smooth muscle cell Rho kinase in rat tail small arteries 1) is in an active state partly determining the level of the myogenic tone, and 2) alters the strength of the myogenic response by changing calcium sensitivity, probably caused by the pressure-induced activation of the kinase.

Investigation of the inhibitory effects of HA-1077 and Y-32885 on the translocation of PKCbetaI, PKCbetaII and PKCzeta in human neutrophils

To transmit the information inside the cell, one possibility is the action of an enzyme called kinase that phosphorylates other proteins. To study these enzymes, chemical compound synthesis was needed to know the function and the mechanism of activation. The major difficulty is creating a specific molecule for one kinase. In this study, we test the action of Rho-kinase inhibitors (HA-1077 and Y-32885) on protein kinase C (PKC) in the respiratory burst in the human polymorphonuclear neutrophils. We have shown that these compounds could inhibit the anion superoxide production. To prove their action on PKC, we have shown a decrease of binding of a specific ligand (phorbol-12,13-dibutyrate) with each inhibitor. During its activation, PKC was translocated from the cytoplasm to the plasmic membrane. We have also shown an inhibition of this translocation, proving an inhibition of PKC by HA-1077 and Y-32885.

Identification of the smooth muscle-specific protein, sm22, as a novel protein kinase C substrate using two-dimensional gel electrophoresis and mass spectrometry

We report a novel method to identify protein kinase C (PKC) substrates. Tissue lysates were fractionated by ion exchange chromatography and used as substrates in in vitro kinase reactions. The phosphorylated proteins were separated using two-dimensional gel electrophoresis. Spots that contained isolated phosphoproteins were excised and digested with trypsin. The tryptic peptides were analyzed using mass spectrometry. While several of the proteins identified using this technique represent known PKC substrates, we identified a new PKC substrate in the initial screen. This protein, sm22, is expressed in smooth muscle cells and served well as a substrate for PKC in vitro. Sm22 is predominantly associated with the actin cytoskeleton. Upon activation of PKC in vivo, sm22 dissociates from the actin cytoskeleton and is distributed diffusely in the cytoplasm. Our data strongly suggest that phosphorylation by PKC controls the intracellular localization of sm22. This demonstrates that our approach, using a complex mixture of proteins as in vitro kinase substrates and subsequently identifying the newly phosphorylated proteins by mass spectrometry, is a powerful method to identify new kinase substrates.

Protein kinase inhibition by fasudil hydrochloride promotes neurological recovery after spinal cord injury in rats

OBJECT

In Japan fasudil hydrochloride (HA1077), a protein kinase inhibitor, is widely administered to prevent vasospasm in patients after subarachnoid hemorrhage. The effects of fasudil on experimental spinal cord injury (SCI) were investigated and compared with those obtained using methylprednisolone.

METHODS

Spinal cord contusion was induced in rats by applying an aneurysm clip extradurally to the spinal cord at T-3 for 1 minute. After injury three groups of rats were treated with intravenously administered saline (control), intraperitoneally administered fasudil (10 mg/kg), or intravenously administered methylprednisolone (four 30 mg/kg injections). Neurological recovery was evaluated periodically over 1 month by using a modified combined behavioral scale and histopathological examination. Leukocyte infiltration near the injury site was evaluated by measuring myeloperoxidase (MPO) activity at 24 hours. Spinal cord blood flow was measured at intervals up to 3 hours after injury by using laser Doppler flowmetry. In rats in the fasudil-treated group significant improvement in modified combined behavioral score was demonstrated at each time point, whereas in the methylprednisolone-treated rats no beneficial effects were shown. In the fasudil-treated group, reduction of traumatic spinal cord damage was evident histologically in the caudal portion of the injured areas, and tissue MPO activity in tissue samples was reduced. Spinal cord blood flow was not significantly different between fasudil-treated and control group rats.

CONCLUSIONS

Fasudil hydrochloride showed promise of effectiveness in promoting neurological recovery after traumatic SCI. Possible mechanisms of this effect include protein kinase inhibition and decreased infiltration by neutrophils.

Thin and thick filament regulation of contractility in experimental cerebral vasospasm

OBJECTIVE

Cerebral vasospasm is a potentially fatal consequence of aneurysmal subarachnoid hemorrhage and influences the prognosis of the patient. The purpose of this study was to evaluate the status of thin (actin) and thick (myosin) filament regulation of smooth muscle contraction in the double-subarachnoid hemorrhage canine model of cerebral vasospasm and to determine the effects of a kinase inhibitor reported to be effective in vasospasm, HA1077, on thin and thick filament regulation.

METHODS

Cerebral vasospasm was assessed by vertebral angiography. Myosin regulatory light chain phosphorylation was measured using glycerol-urea gels, whereas protein levels of the thin filament-associated protein calponin were measured by Western blot.

RESULTS

The basilar arteries of dogs in which subarachnoid hemorrhage was induced narrowed to 36% +/- 2.0% of their size on the first day (n = 12). The phosphorylation of the regulatory light chain tended to increase, but the change did not reach statistical significance (35% +/- 5.9% [n = 12] versus 25% +/- 4.8% [n = 10] in control arteries). In contrast to this increase, significant degradation of calponin was observed in the samples from vasospastic dogs (85.4% +/- 5.45% [n = 5] versus 15.2% +/- 6.21% [n = 5]; P < 0.01). Prophylactic treatment with intravenous injections of HA1077 at 0.67 mg/kg b.i.d. significantly inhibited vasospasm (diameters, 65% +/- 10.2% of Day 1 diameters [n = 5]; P < 0.05), and calponin degradation (57.8% +/- 13.9% [n = 4]) was substantially reduced.

CONCLUSION

These data suggest that degradation of the thin filament-associated protein calponin plays a role in cerebral vasospasm and that the antivasospastic action of HA1077 is, at least in part, due to prevention of calponin degradation.

Inhibition of neutrophil migration by a protein kinase inhibitor for the treatment of ischemic brain infarction

This study investigated the therapeutic potential of agents that inhibited neutrophil infiltration in cerebral ischemic infarction. The migration of neutrophils elicited by N-formyl-methionyl-leucyl-phenylalanine, tumor necrosis factor, C5a or platelet-activating factor was potently inhibited by fasudil, an inhibitor of protein kinases including rho kinase, protein kinase C and myosin light chain kinase, and hydroxy fasudil, a metabolite of fasudil, in vitro. In a microembolism model in rats, myeloperoxidase-quantified neutrophil accumulation in the ischemic brain was observed 24 hr after embolization. Intravenous administration of fasudil prevented the accumulation of neutrophils. In rats given fasudil, myeloperoxidase activity in the ipsilateral hemisphere (0.04+/-0.01 unit/g wet tissue) was significantly lower than that in ischemic rats (0.11+/-0.02 unit/g wet tissue). Fasudil also significantly reduced the size of the infarct area and improved neurological functions. These results suggest that neutrophil infiltration into the ischemic brain is involved in the pathogenesis of ischemic injury and that inhibiting neutrophil infiltration may provide an effective therapeutic intervention to reduce ischemic injury.