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Biomedical subjects

Y Fukata

Publications and source records attributed to Y Fukata.

At least 19 recordsLinked to original sources
PubMed2003

[Familial aortic dissection; cases involving a father, mother, and son].

The occurrence of familial aortic dissection is rare in cases that are not linked to Marfan syndrome. We report the 3 cases of acute aortic dissection, involving both parents and their son. Case 1 (father case): 79-year-old male visited a nearby doctor complaining of severe chest and back pain. He was diagnosed as acute aortic dissection (Stanford type A). An emergency operation was carried out and he had an artificial vascular replacement of ascending aorta and arch portion. Case 2 (mother case): 73-year-old female was treated for hypertension. Suddenly, she had a terrible epigastralgia and back pain. The contrast enhanced chest computed tomography (CT) revealed an acute aortic dissection (Stanford type A). The ascending aortic aneurysm ruptured in the ambulance while she was transferred to our hospital. She arrived at our hospital after cardiac and respiratory arrest. We attempted to perform cardiac massage, but we could not bring her back to life. Case 3 (son case): 48-year-old male was transferred to our hospital diagnosed with acute aortic dissection (Stanford type A). The ascending aorta replacement was performed on the same day. We were able to save cases 1 and 3 by performing surgery. Aortic dissection is thought to be the disease of medial degeneration. Hereditary links to aortic dissection are not well understood, with the exception of Marfan syndrome cases. The investigation of genetic mechanisms related to aortic dissection will be expected in the future.

Acute Disease↗
PubMed2002

[MIDCAB for redo patients using the LITA-RA composite graft].

Redo coronary artery bypass grafting (CABG) is associated with higher mortality, low-output syndrome, perioperative myocardial infarction than primary CABG. Minimally invasive direct coronary artery bypass grafting (MIDCAB) technique avoids the manipulation of old graft and injury of the adhesive heart in redo operation. We performed the MIDCAB procedure for 2 redo cases using the left internal thoracic artery (LITA)-radial artery (RA) composite graft. The LITA-RA composite graft was anastomosed to the left anterior descending branch (LAD) through small left anterior thoracotomy without cardiopulmonary bypass. Postoperative coronary artery graphy shows the widely patent of new graft. The MIDCAB procedure using the LITA-RA composite graft is safe and useful to regulate the bypass graft length and avoid the widely harvest of LITA in redo operation.

Aged↗
PubMed2002

[A difficult case of antiphospholipid syndrome with repeated restenosis of coronary artery and grafts].

A 65-year-old man complained of exertional angina. Coronary angiography revealed 99% stenosis in the left anterior descending artery (LAD). He underwent percutaneous transluminal coronary angioplasty (PTCA) and stenting. Repeat angiography demonstrated restenosis of the previous PTCA and stenting site. He underwent coronary artery bypass grafting (CABG) with placement of the left internal thoracic artery (LITA) to LAD. Chest discomfort and V1-V3 ST elevation appeared on the first post operative day. Coronary angiography revealed occlusion of the LITA graft. He underwent re-operation. Because the radial artery was severely sclerotic, the great saphenous vein was used for the graft. Two weeks later, he began to show edema in the left lower extremity. Echoangiogram showed occlusion of the left deep vein with thrombus. He tested positive for anticardiolipin IgG and IgM antibodies. Eighteen months after re-operation, he had recurrent chest discomfort on exertion. Coronary angiography revealed 90% stenosis of the anastomosis (SVG-LAD). A second re-operation was performed. We used the right internal thoracic artery (RITA) for the graft. The postoperative angiography showed patent graft. The patient has been doing well without any complications.

Aged↗
PubMed2001

Rho-Rho-kinase pathway in smooth muscle contraction and cytoskeletal reorganization of non-muscle cells.

Hypercontraction or abnormal contraction of vascular smooth muscle is a major cause of diseases such as hypertension and vasospasm of the coronary and cerebral arteries. A better understanding of the mechanism of regulation of smooth muscle contraction should lead to improved treatments for such diseases. Recent studies have revealed important roles for the small GTPase Rho and its effector, Rho-associated kinase (Rho kinase) in Ca2+ independent regulation of smooth muscle contraction. The Rho-Rho-kinase pathway modulates the level of phosphorylation of the myosin light chain of myosin II, mainly through inhibition of myosin phosphatase, and contributes to agonist-induced Ca2+ sensitization in smooth muscle contraction. Rho-Rho-kinase mechanisms also participate in a variety of the cellular functions of non-muscle cells, such as stress-fibre formation, cytokinesis and cell migration. This review summarizes the role of the Rho-Rho-kinase pathway in contractile processes of smooth muscle and in non-muscle cell functions, and the pathophysiological implications of this pathway.

Animals↗
PubMed2001

[Two cases of stent graft repair for thoracic aortic dissection: usefulness of three-dimensional computed tomogram].

We carried out stent graft repair in two patients with Stanford type B thoracic aortic dissection. A 51-year-old male was admitted to our hospital because of thoracic aortic dissection. Chest CT revealed an aneurysm of the distal aortic arch. The entry was pointed out 1 cm distal from the take off of the left subclavian artery in three-dimensional CT (3 D-CT). He was treated with a Gianturco stent which was anchored into the 30 mm Hemashield graft under selective cerebral perfusion. Another case was a 72-year-old male with a descending aortic aneurysm. 3 D-CT showed that the entry existed 4 cm proximal to the celiac artery. We performed transluminal implantation of the spiral Z-stent covered with the woven Dacron graft. 3 D-CT was useful for the preoperative management and the surgical treatment of thoracic aortic dissection.

Aged↗
PubMed2000

Regulation and functions of Rho-associated kinase.

Remarkable progress has been made in understanding effector molecules of small GTPase Rho, especially Rho-associated kinase (Rho-kinase/ROK/ROCK), in the past 5 years. Rho-associated kinase appears to mediate a large proportion of the signals from Rho and regulate dynamic reorganization of cytoskeletal proteins, such as stress fiber and focal adhesion formation. Several substrates of Rho-associated kinase have been reported and their cellular functions unraveled. In this review, we focus on the regulation and cellular functions of Rho-associated kinase.

Animals↗
PubMed2000

Elongation factor-1 alpha is a novel substrate of rho-associated kinase.

Rho-associated kinase (Rho-kinase), which is activated by the Rho small GTPase, phosphorylates the myosin-binding subunit (MBS) of myosin phosphatase, myosin light chain (MLC), the ERM family proteins, and adducin, thereby regulating the formation of stress fibers, focal adhesions, microvillus formation, and cell motility. Here, to further understand the role of Rho-kinase in the regulation of the numerous cellular processes by Rho, we purified a novel substrate of Rho-kinase having a molecular mass of 48 kDa (p48) from a rat liver cytosol extract. Mass spectral analysis revealed p48 to be elongation factor-1 alpha (EF-1 alpha), which is known as an actin-binding protein besides a cofactor of polypeptide elongation. Rho-kinase directly phosphorylated recombinant EF-1alpha in vitro. A high- speed cosedimentation assay revealed that phosphorylation of EF-1 alpha by Rho-kinase decreased the binding activity of EF-1 alpha to filamentous actin (F-actin). A low-speed sedimentation assay revealed that phosphorylation of EF-1 alpha by Rho-kinase decreased the F-actin-bundling activity. In addition, EF-1 alpha bound to MBS of myosin phosphatase, suggesting that both Rho-kinase and myosin phosphatase regulate the phosphorylation state of EF-1 alpha downstream of Rho as other substrates of Rho-kinase, i.e., MLC, adducin, and the ERM family. These results suggest that the Rho/Rho-kinase pathway regulates the organization of actin cytoskeleton via the phosphorylation of EF-1 alpha.

Actins↗
PubMed2000

Inhibition of myosin phosphatase by upregulated rho-kinase plays a key role for coronary artery spasm in a porcine model with interleukin-1beta.

BACKGROUND: We recently demonstrated that the Rho-kinase-mediated pathway plays an important role for coronary artery spasm in our porcine model with interleukin-1beta (IL-1beta). In this study, we examined whether or not Rho-kinase is upregulated at the spastic site and if so, how it induces vascular smooth muscle hypercontraction. METHODS AND RESULTS: Segments of the left porcine coronary artery were chronically treated from the adventitia with IL-1beta-bound microbeads. Two weeks after the operation, as reported previously, intracoronary serotonin repeatedly induced coronary hypercontractions at the IL-1beta-treated site both in vivo and in vitro, which were markedly inhibited by Y-27632, one of the specific inhibitors of Rho-kinase. Reverse transcription-polymerase chain reaction analysis demonstrated that the expression of Rho-kinase mRNA was significantly increased in the spastic compared with the control segment. Western blot analysis showed that during the serotonin-induced contractions, the extent of phosphorylation of the myosin-binding subunit of myosin phosphatase (MBS), one of the major substrates of Rho-kinase, was significantly greater in the spastic than in the control segment and that the increase in MBS phosphorylations was also markedly inhibited by Y-27632. There was a highly significant correlation between the extent of MBS phosphorylations and that of contractions. CONCLUSIONS: These results indicate that Rho-kinase is upregulated at the spastic site and plays a key role in inducing vascular smooth muscle hypercontraction by inhibiting myosin phosphatase through the phosphorylation of MBS in our porcine model.

Animals↗
PubMed2000

Phosphorylation of ERM proteins at filopodia induced by Cdc42.

BACKGROUND: ERM (ezrin, radixin, and moesin) proteins function as membrane-cytoskeletal linkers, and are known to be localized at filopodia and microvilli-like structures. We have shown that Rho-associated kinase (Rho-kinase)/ROKalpha/ROCK II phosphorylates moesin at Thr-558 at the lower stream of Rho, and the phosphorylation is crucial to the formation of microvilli-like structures (Oshiro, N., Fukata, Y. & Kaibuchi, K. (1998) Phosphorylation of moesin by Rho-associated kinase (Rho-kinase) plays a crucial role in the formation of microvilli-like structures. J. Biol. Chem. 273, 34663- 34666). However, the role of ERM proteins in the formation of filopodia is less well characterized. RESULTS: Here we examined the phosphorylation state of ERM during filopodia formation induced by Cdc42 using the antibody recognizing ERM proteins phosphorylated at COOH (C)-terminal threonine. When NIH 3T3 cells were transfected with constitutively active Cdc42 (Cdc42V12), filopodia formation was induced and phosphorylation of ERM at C-terminal threonine was observed at the tip of filopodia, while the phosphorylation levels of ERM were lower and phosphorylated ERM was distributed throughout the cytoplasm in the control cells. We also showed that Myotonic dystrophy kinase-related Cdc42-binding kinase (MRCK) which has been identified as an effector of Cdc42, phosphorylated moesin at C-terminal threonine in a cell-free system. Coexpression of the dominant negative form of MRCK inhibited both the formation of filopodia and accumulation of C-terminal threonine-phosphorylated ERM proteins at filopodia induced by Cdc42V12. CONCLUSION: The formation of filopodia induced by Cdc42 is accompanied by phosphorylation of ERM proteins, and MRCK is a candidate for the kinase that phosphorylates ERM proteins at filopodia.

3T3 Cells↗
PubMed1999

Activation of moesin and adducin by Rho-kinase downstream of Rho.

The Rho GTPase (Rho) is a member of the Rho family, which belongs to the Ras superfamily of GTP-binding proteins. Like other GTP-binding proteins, Rho exists in two conformational states, an inactive GDP-bound form and an active GTP-bound form. Active Rho interacts with specific effectors to regulate the actin cytoskeleton and to mediate a variety of biological functions in cells. Rho-associated kinase (Rho-kinase) is the most studied Rho-effector, and studies of its biochemical and cell biological functions have provided us with useful information for understanding the molecular mechanisms of the actions of Rho. This review aims to summarize the roles of Rho and Rho-kinase in the regulation of the cytoskeletons.

Calmodulin-Binding Proteins↗
PubMed1999

Phosphorylation of myosin-binding subunit (MBS) of myosin phosphatase by Rho-kinase in vivo.

Rho-associated kinase (Rho-kinase), which is activated by the small GTPase Rho, phosphorylates myosin-binding subunit (MBS) of myosin phosphatase and thereby inactivates the phosphatase activity in vitro. Rho-kinase is thought to regulate the phosphorylation state of the substrates including myosin light chain (MLC), ERM (ezrin/radixin/moesin) family proteins and adducin by their direct phosphorylation and by the inactivation of myosin phosphatase. Here we identified the sites of phosphorylation of MBS by Rho-kinase as Thr-697, Ser-854 and several residues, and prepared antibody that specifically recognized MBS phosphorylated at Ser-854. We found by use of this antibody that the stimulation of MDCK epithelial cells with tetradecanoylphorbol-13-acetate (TPA) or hepatocyte growth factor (HGF) induced the phosphorylation of MBS at Ser-854 under the conditions in which membrane ruffling and cell migration were induced. Pretreatment of the cells with Botulinum C3 ADP-ribosyltransferase (C3), which is thought to interfere with Rho functions, or Rho-kinase inhibitors inhibited the TPA- or HGF-induced MBS phosphorylation. The TPA stimulation enhanced the immunoreactivity of phosphorylated MBS in the cytoplasm and membrane ruffling area of MDCK cells. In migrating MDCK cells, phosphorylated MBS as well as phosphorylated MLC at Ser-19 were localized in the leading edge and posterior region. Phosphorylated MBS was localized on actin stress fibers in REF52 fibroblasts. The microinjection of C3 or dominant negative Rho-kinase disrupted stress fibers and weakened the accumulation of phosphorylated MBS in REF52 cells. During cytokinesis, phosphorylated MBS, MLC and ERM family proteins accumulated at the cleavage furrow, and the phosphorylation level of MBS at Ser-854 was increased. Taken together, these results indicate that MBS is phosphorylated by Rho-kinase downstream of Rho in vivo, and suggest that myosin phosphatase and Rho-kinase spatiotemporally regulate the phosphorylation state of Rho-kinase substrates including MLC and ERM family proteins in vivo in a cooperative manner.

Actins↗
PubMed1999

Phosphorylation of adducin by Rho-kinase plays a crucial role in cell motility.

Adducin is a membrane skeletal protein that binds to actin filaments (F-actin) and thereby promotes the association of spectrin with F-actin to form a spectrin-actin meshwork beneath plasma membranes such as ruffling membranes. Rho-associated kinase (Rho- kinase), which is activated by the small guanosine triphosphatase Rho, phosphorylates alpha-adducin and thereby enhances the F-actin-binding activity of alpha-adducin in vitro. Here we identified the sites of phosphorylation of alpha-adducin by Rho-kinase as Thr445 and Thr480. We prepared antibody that specifically recognized alpha-adducin phosphorylated at Thr445, and found by use of this antibody that Rho-kinase phosphorylated alpha-adducin at Thr445 in COS7 cells in a Rho-dependent manner. Phosphorylated alpha-adducin accumulated in the membrane ruffling area of Madin-Darby canine kidney (MDCK) epithelial cells and the leading edge of scattering cells during the action of tetradecanoylphorbol-13-acetate (TPA) or hepatocyte growth factor (HGF). The microinjection of Botulinum C3 ADP-ribosyl-transferase, dominant negative Rho-kinase, or alpha-adducinT445A,T480A (substitution of Thr445 and Thr480 by Ala) inhibited the TPA-induced membrane ruffling in MDCK cells and wound-induced migration in NRK49F cells. alpha-AdducinT445D,T480D (substitution of Thr445 and Thr480 by Asp), but not alpha-adducinT445A,T480A, counteracted the inhibitory effect of the dominant negative Rho-kinase on the TPA-induced membrane ruffling in MDCK cells. Taken together, these results indicate that Rho-kinase phosphorylates alpha-adducin downstream of Rho in vivo, and that the phosphorylation of adducin by Rho-kinase plays a crucial role in the regulation of membrane ruffling and cell motility.

Amino Acid Sequence↗
PubMed1999

Evaluation of the internal thoracic arterial graft patency by the transthoracic Doppler method under continuous intravenous infusion of adenosine triphosphate disodium.

Usefulness of the Doppler method under continuous infusion of adenosine triphosphate disodium (ATP) for improvement of accuracy in the diagnosis of the left internal thoracic arterial graft (LITA) patency was examined using transthoracic ultrasonic echocardiography. 1) Influence of ATP on the Doppler velocity in a graft was examined in 7 patients with good LITA grafts using physiological saline as the control. In the ATP group, 80 mg of ATP was dissolved in 20 ml physiological saline and continuously infused at 0.14 mg/kg/min. In the saline group, an equal volume of physiological saline was administered and the blood flow velocity in the LITA was recorded continuously by the transthoracic Doppler method from the supraclavicular fossa approach. Results; ATP administration increased the blood flow velocity in the LITA and the rate of increase was 48.3% for systolic peak velocity, 111% for diastolic peak velocity, 64.4% for systolic time velocity integral and 99% for diastolic time velocity integral indicating particularly high rates of increase in diastolic components. The diastolic/systolic peak velocity ratio or diastolic fraction did not increase significantly. In the saline group, none of the parameters showed a change. 2) Angiographic findings of the LITA were compared with the measurement values of the diastolic components by the Doppler method to examine usefulness of diastolic component measurement with ATP infusion for diagnosis of LITA patency. Subjects were 19 patients with good LITA (group A) and 8 patients with bad LITA (group B). Results; while there were significant differences in the mean baseline diastolic peak velocity, mean diastolic time velocity integral and mean diastolic fraction between the groups, overlapping was seen in individual cases. However, the inter-group differences were more distinct by ATP infusion and the borderline values were 30 cm/sec for diastolic peak velocity and 10 for diastolic time velocity integral. 3) Reliability of the diagnosis for LITA patency by measuring the diastolic components using the Doppler method with ATP infusion was examined and compared with the angiographic findings as the gold standard. Subjects were 27 patients and the diagnostic criteria for good LITA were set at 30 cm/sec for diastolic peak velocity and 10 for diastolic time velocity integral. Results; sensitivity and specificity of the Doppler method with ATP infusion were 100% for diagnosis of LITA patency by measuring the diastolic components. Conclusion, in diagnosis of LITA patency by the transthoracic ultrasonic cardiography, diagnostic accuracy was improved by measuring the diastolic parameters under continuous infusion of ATP.

Adenosine Triphosphate↗
PubMed1998

Phosphorylation of moesin by rho-associated kinase (Rho-kinase) plays a crucial role in the formation of microvilli-like structures.

Rho-associated kinase (Rho-kinase), which is activated by the small GTPase Rho, phosphorylates moesin at Thr558 in vitro. Here, using a site- and phosphorylation state-specific antibody, we found that the expression of dominant active RhoA in COS7 cells induced moesin phosphorylation and the formation of microvilli-like structures at apical membranes where the Thr558-phosphorylated moesin accumulated, whereas the expression of dominant negative Rho-kinase inhibited both of these processes. The expression of dominant active Rho-kinase also induced moesin phosphorylation. When COS7 cells expressing moesin or moesinT558A (substitution of Thr by Ala) were cultured under serum-depleted conditions, there were few microvilli-like structures, whereas microvilli-like structures remained in the cells expressing moesinT558D (substitution of Thr by Asp). The expression of moesinT558A inhibited the dominant active RhoA-induced formation of microvilli-like structures. These results indicate that Rho-kinase regulates moesin phosphorylation downstream of Rho in vivo and that the phosphorylation of moesin by Rho-kinase plays a crucial role in the formation of microvilli-like structures.

Animals↗
PubMed1998

Association of the myosin-binding subunit of myosin phosphatase and moesin: dual regulation of moesin phosphorylation by Rho-associated kinase and myosin phosphatase.

The small GTPase Rho is believed to regulate the actin cytoskeleton and cell adhesion through its specific targets. We previously identified the Rho targets: protein kinase N, Rho-associated kinase (Rho-kinase), and the myosin-binding subunit (MBS) of myosin phosphatase. We found that in MDCK epithelial cells, MBS accumulated at the tetradecanoylphorbol-13-acetate (TPA)-induced membrane ruffling area, where moesin, a member of the ERM (ezrin, radixin, and moesin) family, was localized. Neither membrane ruffling nor an accumulation of moesin and MBS at the free-end plasma membrane was induced when MDCK cells were stimulated with TPA after the microinjection of C3, which ADP-ribosylates and inactivates Rho. MBS was colocalized with moesin at the cell-cell contact sites in MDCK cells. We also found that moesin was coimmunoprecipitated with MBS from MDCK cells. Recombinant MBS interacted with the amino-terminal domains of moesin and ezrin. Myosin phosphatase composed of the catalytic subunit and MBS showed phosphatase activity toward moesin, which was phosphorylated by Rho-kinase. The phosphatase activity was inhibited when MBS was phosphorylated by Rho-kinase. These results suggest that MBS is recruited with moesin to the plasma membrane and that myosin phosphatase and Rho-kinase regulate the phosphorylation state of moesin downstream of Rho.

ADP Ribose Transferases↗
PubMed1998

Regulation of the association of adducin with actin filaments by Rho-associated kinase (Rho-kinase) and myosin phosphatase.

The small GTPase Rho is believed to regulate the actin cytoskeleton and cell adhesion through its specific targets. We previously identified the Rho targets: protein kinase N, Rho-associated kinase (Rho-kinase), and the myosin-binding subunit (MBS) of myosin phosphatase. Here we purified MBS-interacting proteins, identified them as adducin, and found that MBS specifically interacted with adducin in vitro and in vivo. Adducin is a membrane-skeletal protein that promotes the binding of spectrin to actin filaments and is concentrated at the cell-cell contact sites in epithelial cells. We also found that Rho-kinase phosphorylated alpha-adducin in vitro and in vivo and that the phosphorylation of alpha-adducin by Rho-kinase enhanced the interaction of alpha-adducin with actin filaments in vitro. Myosin phosphatase composed of the catalytic subunit and MBS showed phosphatase activity toward alpha-adducin, which was phosphorylated by Rho-kinase. This phosphatase activity was inhibited by the phosphorylation of MBS by Rho-kinase. These results suggest that Rho-kinase and myosin phosphatase regulate the phosphorylation state of adducin downstream of Rho and that the increased phosphorylation of adducin by Rho-kinase causes the interaction of adducin with actin filaments.

Actins↗
PubMed1998

Myosin II activation promotes neurite retraction during the action of Rho and Rho-kinase.

BACKGROUND: The Rho small GTPase regulates myosin II activity through the phosphorylation of the myosin light chain (MLC) by activating Rho-kinase, which is a target of Rho. Several lines of evidence point to an important role of Rho in the action of lysophosphatidic acid (LPA) and thrombin in provoking neurite retraction in N1E-115 neuroblastoma cells. RESULTS: Here we examined whether Rho-kinase and myosin II are involved in neurite retraction in N1E-115 cells. We showed that the expression of constitutively active forms of Rho-kinase induced neurite retraction in NIE-115 cells and MLC phosphorylation in NIH 3T3 cells, whereas the expression of dominant negative forms of Rho-kinase inhibited the LPA-induced neurite retraction in N1E-115 cells and the serum-induced MLC phosphorylation in NIH 3T3 cells. The expression of mutant MLCT18D,S19D (substitution of Thr and Ser by Asp), which is known to lead to the activation of myosin ATPase and a conformational change of myosin II when reconstituted with myosin heavy chains in vitro, also promoted neurite retraction. CONCLUSION: These results indicate that Rho-kinase is involved in the LPA-induced neurite retraction downstream of Rho, and that myosin II activation promotes neurite retraction downstream of Rho and Rho-kinase.

3T3 Cells↗