Expression and functional role of formyl peptide receptor in human bone marrow-derived mesenchymal stem cells

AbstractWe investigated the expression of formyl peptide receptor (FPR) and its functional role in human bone marrow-derived mesenchymal stem cells (MSCs). We analyzed the expression of FPR by using ligand-binding assay with radio-labeled N-formyl-met-leu-phe (fMLF), and found that MSCs express FPR. FMLF stimulated intracellular calcium increase, mitogen-activated protein kinases activation, and Akt activation, which were mediated by Gi proteins. MSCs were chemotactically migrated to fMLF. FMLF-induced MSC chemotaxis was also completely inhibited by pertussis toxin, LY294002, and PD98059, indicating the role of Gi proteins, phosphoinositide 3-kinase, and extracellular signal regulated protein kinase. N-terminal fragment of annexin-1, Anx-1(2–26), an endogenous agonist for FPR, also induced chemotactic migration of MSCs. Thus MSCs express functional FPR, suggesting a new (patho)physiological role of FPR and its ligands in regulating MSC trafficking during induction of injured tissue repair

Bupivacaine Induced Cardiac Toxicity Mimicking an Acute Non-ST Segment Elevation Myocardial Infarction

Bupivacaine is widely used as a local anesthetic. Central nervous system (CNS) and cardiovascular toxicity are well known side effects. However, there has been no report of bupivacaine-induced myocardial injury. We present a case of bupivacaine cardiac toxicity mimicking an acute non-ST segment elevation myocardial infarction, which was eventually diagnosed as bupivacaine-induced cardiac toxicity without CNS toxicity. As soon as a healthy young woman at a private clinic was given a spinal anesthesia of 6 mg bupivacaine for hemorrhoidectomy, she developed arrhythmia and hypotension. She was transferred to our emergency room. There was an accelerated idioventricular rhythm with ST segment depression on electrocardiogram, coarse breathing sounds with rales on whole lung field and a butterfly sign on the chest radiograph. 2D transthoracic echocardiography (TTE) revealed reduced left ventricle systolic ejection fraction (approximately 27%). There was regional wall motion abnormality of the left ventricle on 2D TTE and the cardiac marker was increased. We diagnosed the patient as having acute non-ST segment elevation myocardial infarction but her impaired cardiac function improved gradually. On the seventh day from admission, there was a complete spontaneous recovery of cardiac function, and coronary angiography revealed a normal coronary artery. Therefore, we firmly believe that bupivacaine directly injures the cardiac cell

Trp-Lys-Tyr-Met-Val-D-Met is a chemoattractant for human phagocytic cells

Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm) is a synthetic peptide that stimulates phosphoinositide (PI) hydrolysis in human leukocytes. The peptide binds to a unique cell surface receptor(s), Recently we had demonstrated that hunan neutrophils, monocytes, and B lymphocytes express this peptide-specific receptor and that stimulation of human leukocytes with the peptide leads to activation of the oxidative respiratory system and the bactericidal activity of neutrophils or monocytes. In this study we showed that the peptide induces chemotaxis of phagocytic leukocytes and studied the signaling pathway leading to chemotaxis in human monocytes. The peptide-induced monocyte chemotaxis is pertussis toxin (PTX)-sensitive. This fact correlates with the peptide's stimulation of PI hydrolysis and intracellular Ca2+ ([Ca2+](i)) release, which is also PTS-sensitive. We demonstrate that the peptide-specific receptor is different from receptor(s) for monocyte chemoattractant protein-1 (MCP-1). We also show that intracellular signaling of WKYMVm leading to monocyte chemotaxis is different from that of MCP-1, The peptide-mediated monocyte chemotaxis is insensitive to protein kinase C (PKC) inhibitor (GF109203X) and butan-1-ol, 1-ol, ruling out PKC and phospholipase D participation in this process. On the other hand, a tyrosine kinase inhibitor (genistein) and RhoA inhibitor (C3 transferase) curtailed the peptide-induced chemotaxis in a concentration-dependent mariner, implying the involvement of tyrosine kinase and RhoA, respectively. Treatment of human monocytes with the peptide stimulates tyrosine phosphorylation of several cellular proteins, including p125FAK and Pyk2 and translocation of RhoA from the cytosol to the membrane. We conclude that WKYMVm induces chemotaxis of human phagocytic leukocytes via unique receptors and signalingclose323

The synthetic chemoattractant peptide, Trp-Lys-Tyr-Met-Val-D-Met, enhances monocyte survival via PKC-dependent Akt activation

Previously, we showed that Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm) stimulates superoxide generation and chemotactic migration in monocytes and neutrophils. In this study, we examined the effect of WKYMVm on monocyte survival. Serum starvation-induced monocyte death was attenuated in the presence of WKYMVm, which was abated when the cells were preincubated with LY294002, suggesting the involvement of phosphoinositide-3-kinase (PI 3-kinase) in the peptide-induced monocyte survival. WKYMVm stimulated ERK and Akt activity via PI 3-kinase activation in monocytes. We also investigated the signaling pathway of WKYMVm-induced ERK and Akt activation. The WKYMVm-induced ERK activation was PI 3-kinase-dependent but PKC-independent. However, Akt activation by WKYMVm was dependent not only on PI 3-kinase but also on the PKC pathway. When monocytes were incubated with WKYMVm, caspase-3 activity, which is important for cell death, was inhibited. Pretreatment of the cells with LY294002, GF109203X, and Go 6976 but not PD98059 blocked WKYMVm-induced monocyte survival and caspase-3 inhibition. In summary, the novel chemoattractant WKYMVm enhances monocyte survival via Akt-mediated pathways, and in this process, PKC and PI 3-kinase act upstream of Aktclose111

ATP-induced mitogenesis is modulated by phospholipase D2 through extracellular signal regulated protein kinase dephosphorylation in rat pheochromocytoma PC12 cells

Extracellular ATP has been known to have many functions as a fast transmitter, and a co-transmitter, and to have morphogenic and mitogenic activity in neuronal cells. Although it was reported that ATP activates phospholipase D (PLD), the role of PLD versus the ATP function was unclear in neuronal cells. In this study, we investigated the role of PLD on the ATP-induced extracellular signal regulated protein kinase (ERK) activation and mitogenic effect in rat pheochromocytoma PC12 cells. In these cells ATP caused PLD2 activation and ERK phosphorylation, which was dramatically reduced by wild-type PLD2-overexpression but not by lipase-inactive-mutant PLD2-overexpression. The accumulation of phosphatidic acid (PA) by preincubating PC12 cells with propranolol (an inhibitor of PA phosphohydrolase) also decreased the ERK phosphorylation. Inhibition of phosphatases; by okadaic acid or pervanadate completely blocked PLD2-dependent ERK dephosphorylation. In addition, ATP-stimulated thymidine incorporation was reduced by the overexpression of wild-type PLD2, but not by the overexpression of lipase-inactive-mutant PLD2. Okadaic acid pretreatment overcame the decrease of ATP-induced thymidine incorporation by PLD2 overexpression. Taken together, we suggest that PLD2 activity might play a negative role in ATP-induced ERK phosphorylation and mitogenic signal possibly through phosphatases. (C) 2001 Elsevier Science Ireland Ltd. All rights reservedclose6

Independent functioning of cytosolic phospholipase A(2) and phospholipase D-1 in Trp-Lys-Tyr-Met-Val-D-Met-induced superoxide generation in human monocytes

Recently, a novel peptide (Trp-Lys-Tyr-Met-Val-D-Met, WKYMVm) has been shown to induce superoxide generation in human monocytes, The peptide stimulated phospholipase A(2) (PLA(2)) activity in a concentration- and time-dependent manner. Superoxide generation as well as arachidonic acid (AA) release evoked by treatment with WKYMVm could be almost completely blocked by pretreatment of the cells with cytosolic PLA(2) (cPLA(2))-specific inhibitors. The involvement of cPLA(2) in the peptide-induced AA release was further supported by translocation of cPLA(2) to the nuclear membrane of monocytes incubated with WKYMVm, WKYMVm-induced phosphatidylbutanol formation was completely abolished by pretreatment with PKC inhibitors. Immunoblot showed that monocytes express phospholipase D-1 (PLD1), but not PLD2, GF109203X as well as butan-1-ol inhibited peptide-induced superoxide generation in monocytes, Furthermore, the interrelationship between the two phospholipases, cPLA(2) and PLD1, and upstream signaling molecules involved in WKYMVm-dependent activation was investigated. The inhibition of cPLA(2) did not blunt peptide-stimulated PLD1 activation or vice versa, Intracellular Ca2+ mobilization was indispensable for the activation of PLD1 as well as cPLA(2), The WKYMVm-dependent stimulation of cPLA(2) activity was partially dependent on the activation of PKC and mitogen-activated protein kinase, while PKC activation, but not mitogen-activated protein kinase activation, was an essential prerequisite for stimulation of PLD,, Taken together, activation of the two phospholipases, which are absolutely required for superoxide generation, takes place through independent signaling pathways that diverge from a common pathway at a point downstream of Ca2+close343