Commentary. Cilostazol inhibits leukocyte integrin Mac-1, leading to a potential reduction in restenosis after coronary stent implantation.
Explore the source record for details and available documents.
Comment↗
Biomedical subjects
Bauer E Sumpio
Publications and source records attributed to Bauer E Sumpio.
Strain-induced vascular endothelial cell proliferation requires PI3K-dependent mTOR-4E-BP1 signal pathway.
The aim of this study was to determine whether the phosphatidylinositol 3-kinase (PI3K)-dependent mammalian target of rapamycin (mTOR)-eukaryotic initiation factor 4E binding protein 1 (4E-BP1) signal pathway and S6 kinase (S6K), the major element of the mTOR pathway, play a role in the enhanced vascular endothelial cell (EC) proliferation induced by cyclic strain. Bovine aortic ECs were subjected to an average of 10% strain at a rate of 60 cycles/min for < or =24 h. Cyclic strain-induced EC proliferation was reduced by pretreatment with rapamycin but not the MEK1 inhibitor PD-98059. The PI3K inhibitors wortmannin and LY-294002 also attenuated strain-induced EC proliferation and strain-induced activation of S6K. Rapamycin but not PD-98059 prevented strain-induced S6K activation, and PD-98059 but not rapamycin prevented strain-induced activation of extracellular signal-regulated kinases 1 and 2. Cyclic strain also activated 4E-BP1, which could be inhibited by PI3K inhibitors. These data suggest that the PI3K-dependent S6K-mTOR-4E-BP1 signal pathway may be critically involved in strain-induced bovine aortic EC proliferation.
3-Phosphoinositide-Dependent Protein Kinases↗
Do estrogen effects on blood vessels translate into clinically significant atheroprotection?
Explore the source record for details and available documents.
Animals↗
John Harvey Kellogg; surgeon, inventor, nutritionist (1852-1943).
Explore the source record for details and available documents.
General Surgery↗
The role of thrombospondin-1 in human disease.
Thrombospondin-1 (TSP-1) is a large matricellular glycoprotein secreted by many cell types. It is a component of the extracellular matrix during active and subacute processes. Due to TSP-1's ability to interact with a variety of matrix proteins and cell-surface receptors, controversy exists about its conflicting functions. In this review, we will discuss the role of TSP-1 in human disease.
Disease↗
Cell signalling in vascular cells exposed to cyclic strain: the emerging role of protein phosphatases.
Phosphorylation of tyrosine or serine/threonine residues of intracellular proteins is a reversible and dynamic process which is essential in controlling cellular growth, migration and survival. The phosphorylation states of numerous intermediary signalling proteins are governed by the opposing activities of protein kinases and phosphatases. Abnormal phosphorylation states have been linked with many human diseases, including cancer, diabetes, hypertension and cardiac hypertrophy. Recently, several reports have described the role of phosphatases in regulating critical cellular functions and signalling pathways in vascular cells. This Review will focus on the significance of several of these phosphatases and present information on the role of protein phosphatase type 2a in endothelial cells exposed to haemodynamic forces.
Animals↗
Fibronectin blocks p38 and jnk activation by cyclic strain in Caco-2 cells.
Diverse repetitive forces deform the intestinal epithelium and basement membrane. Such repetitive deformation induces intestinal epithelial proliferation, differentiation, and intracellular signaling. Although at least some deformation-induced signals probably involve integrins, the matrix-dependence of these signals is poorly understood. We compared rapid strain activation of p38 and jnk in human Caco-2 intestinal epithelial cells cultured on collagen I, collagen IV, laminin, and tissue fibronectin. These signals were inhibited in cells on a fibronectin substrate, but activated by strain on collagens and laminin. Furthermore, adding 300 microg/ml plasma fibronectin (approximately the concentration found in plasma) to the culture medium inhibited strain activation of p38 and jnk in cells cultured on collagen. Since tissue and plasma fibronectin levels vary in acute or chronic inflammatory or infectious conditions, these results suggest that tissue or plasma fibronectin may modulate the intestinal epithelial response to repetitive deformation.
Caco-2 Cells↗
Thrombospondin-1-induced vascular smooth muscle cell chemotaxis: the role of the type 3 repeat and carboxyl terminal domains.
Thrombospondin-1 (TSP-1), an acute phase reactant implicated in vascular disease, is a matricellular glycoprotein with six domains that confer different functions. The authors have shown TSP-1 induces vascular smooth muscle cell (VSMC) chemotaxis via extracellular signal-regulated kinases-1 and -2 (ERK) and p38 kinase (p38) and that a fusion protein of the carboxyl terminal (COOH) and type 3 repeat (T3) domains independently induce VSMC chemotaxis. The purpose of this study was to determine whether COOH-, T3-induced VSMC chemotaxis, or both, is dependent upon ERK or p38 activation. To determine if the T3, COOH, or type 2 repeat domain (T2, control domain not associated with chemotaxis) activate ERK, p38, or both, VSMCs were exposed to each fusion protein (20 microg/ml for 15, 30, 60, or 120 min), serum-free media (SFM, negative control), or TSP-1 (20 microg/ml for 30 min, positive control). Western immunoblotting was performed for activation studies. Using a microchemotaxis chamber, VSMCs pre-incubated in SFM, DMSO (vehicle control), PD98059 (10 microM), or SB202190 (10 microM) were exposed to each domain, TSP-1, or SFM. After 4 h (37 degrees C), migrated VSMCs were recorded as cells/five fields (400 x) and analyzed by paired t-test. ERK was activated by T2, T3, and COOH. However, p38 was activated by T3 and COOH, but not T2. T3 and COOH-induced VSMC chemotaxis were inhibited by PD98059 or SB202190, but more completely by SB202190. The T2 domain had no effect on VSMC chemotaxis. These results suggest activation of the p38 pathway may be more specific than ERK for COOH- and T3-induced VSMC chemotaxis.
Animals↗
Regulation of the intestinal epithelial response to cyclic strain by extracellular matrix proteins.
Repetitive mechanical deformation may stimulate intestinal epithelial proliferation. Because the extracellular matrix modulates static intestinal epithelial biology, we examined whether matrix proteins influence intestinal epithelial responses to deformation. Human Caco-2BBE cells and nontransformed human enterocytes (HIPEC) were subjected to 10% average cyclic strain at 10 cycles/min on flexible membranes precoated with matrix proteins without or with plasma fibronectin or functional anti-integrin antibodies in the medium. Strain stimulated proliferation, focal adhesion kinase, extracellular signal-regulated protein kinase (ERK), p38, and Jun N-terminal kinase similarly on collagen I or IV, and more weakly on laminin, but had no effect on fibronectin. MEK blockade (PD98059) prevented strain-stimulated proliferation on collagen but did not affect proliferation on fibronectin. Adding tissue fibronectin to a collagen substrate or plasma fibronectin to the media suppressed strain s mitogenic and signal effects, but not those of epidermal growth factor. Functional antibodies to the alpha5 or alpha(v) integrin subunit blocked strain's effects on Caco-2 proliferation and ERK activation, although ligation of the alpha2 or alpha6 subunit did not. Repetitive strain also stimulated, and fibronectin inhibited, human intestinal primary epithelial cell proliferation. Repetitive deformation stimulates transformed and nontransformed human intestinal epithelial proliferation in a matrix-dependent manner. Tissue or plasma fibronectin may regulate the intestinal epithelial response to strain via integrins containing alpha5 or alpha(v).
Caco-2 Cells↗
Role of PP2A in the regulation of p38 MAPK activation in bovine aortic endothelial cells exposed to cyclic strain.
We have previously reported that cyclic strain results in rapid phosphorylation of p38 mitogen activated protein kinase (MAPKs). The aim of this study was to examine the role of protein phosphatase type 2A (PP2A) in regulating p38 MAPK activation in bovine aortic endothelial cells exposed to cyclic strain. In this study, we demonstrate that the catalytic subunit of PP2A is tyrosine phosphorylated by cyclic strain, resulting in inhibition of phosphatase activity. Okadaic acid, an inhibitor of PP2A at lower concentrations increased phosphorylation of p-38. Phospho-p38 MAPK physically associated with the catalytic subunit, PP2Ac. Phospho-p38 MAPK was dephosphorylated by purified PP2Ac in cell lysates, but if pretreated with okadaic acid, phospho-p38 MAPK was maintained. Taken together, our result suggests that PP2A plays a regulatory role in p38 MAPK activation in endothelial cells exposed to cyclic strain.
Animals↗
Involvement of S6 kinase and p38 mitogen activated protein kinase pathways in strain-induced alignment and proliferation of bovine aortic smooth muscle cells.
Bovine aortic smooth muscle cell (SMC) phenotype can be altered by physical forces. This has been demonstrated by cyclic strain-induced changes in proliferation and alignment. However, the intracellular coupling pathways remain ill defined. In the present study, we examined whether the p38 and S6 kinase pathway were involved in the mitogenic and morphological changes seen in SMCs exposed to cyclic strain. We seeded bovine aortic SMCs on silastic membranes that were deformed with 150-mmHg vacuum. Cyclic strain induced both alignment and proliferation of SMCs. SB202190, a specific inhibitor of p38, hindered SMC alignment, but not proliferation. Rapamycin, a specific inhibitor of the mTOR-S6 kinase pathway, attenuated strain-induced proliferation, but not alignment. Peak activation of p38 and S6 kinase was 351 +/- 76.9% at 5 min and 363 +/- 56.2% at 60 min compared with static control, respectively (P < 0.05). The results suggest that strain-induced SMC alignment is dependent on activation of p38, but not S6 kinase. Strain induced SMC proliferation is S6 kinase, but not p38 activation, dependent.
Animals↗
Thrombospondin-1 induces matrix metalloproteinase-2 activation in vascular smooth muscle cells.
INTRODUCTION: Thrombospondin-1 (TSP-1), an extracellular matrix (ECM) glycoprotein, is associated with a variety of cellular processes relevant to atherosclerosis and intimal hyperplasia, including vascular smooth muscle cell (VSMC) migration. Matrix metalloproteinase-2 (MMP2) is associated with basement membrane and ECM degradation, important processes for cell migration. We hypothesized that TSP-1 modulates MMP2 activity in VSMCs and is critical for VSMC migration. METHODS: Quiescent bovine aortic VSMCs (48 hours) were incubated in serum-free media (SFM) with or without TSP-1 (10 or 20 microg/mL). Gelatinase activity was measured with zymography to determine pro-MMP2 and MMP2 activity. MMP2 messenger RNA expression was determined with Northern blot analysis. Invasion assays were performed. A binding assay was used to determine the specificity of TSP-1 binding to MMP2. Blots were quantified with densitometry, and all comparisons were made with a paired t test. RESULTS: TSP-1 induced production of activated forms of MMP2, as well as upregulation of pro-MMP2. MMP2 mRNA was upregulated 1.7-fold by TSP-1 at 10 and 20 microg/mL. GM6001, an MMP inhibitor, inhibited VSMC migration across the matrix barrier, whereas migration that occurred in the absence of the matrix barrier was unaffected. With a binding assay, TSP-1 interacted physically with MMP2, and TSP-1-bound MMP2 showed the strongest binding activity in comparison with collagen I, fibronectin, and elastin. CONCLUSION: TSP-1 induced MMP2 activation through transcriptional and posttranslational mechanisms. These findings imply that MMP2 activation is relevant to the mechanism of TSP-1-induced VSMC migration.
Animals↗
Oscillatory shear stress increases smooth muscle cell proliferation and Akt phosphorylation.
PURPOSE: Hemodynamic forces affect smooth muscle cell (SMC) proliferation and migration both in vitro and in vivo. However, the effects of oscillatory shear stress (SS) on SMC proliferation and signal transduction pathways that control survival are not well described. METHODS: Bovine aortic SMC were exposed to arterial levels of oscillatory SS (14 dyne/cm(2)) with an orbital shaker; control cells were exposed to static conditions (0 dyne/cm(2)). Cell number and (3)[H]thymidine incorporation were measured after 1, 3, or 5 days of SS. Activation of the Akt pathway was assessed with the Western blot technique. Specificity of the phosphatidylinositol 3-kinase (PI3K) pathway was determined with the Western blot technique with the inhibitors LY294002 (10 micromol/L) or wortmannin (25 nmol/L). RESULTS: Arterial levels of oscillatory SS increased SMC cell number by 20.1 +/- 3.7% and (3)[H]thymidine incorporation by 33.4% +/- 6.8% at 5 days. To identify whether SS increased activity of the SMC survival pathway, Akt activation was measured. SMC exposed to SS demonstrated increased Akt phosphorylation compared with control cells, with maximal phosphorylation at 60 minutes. Both PI3K inhibitors specifically inhibited the increase in Akt phosphorylation in SMC exposed to oscillatory SS. CONCLUSION: SMC directly respond to oscillatory SS by increasing DNA synthesis, proliferation, and activation of the PI3K-Akt signal transduction pathway. These results suggest a mechanism of SMC survival and proliferation in response to endothelial-denuding arterial injury.
Animals↗
Vascular evaluation and arterial reconstruction of the diabetic foot.
Findings of diminished or absent pulses, pallor on elevation, redness of the foot on lowering of the leg, sluggish refilling of the toe capillaries, and thickened nails or absence of toe hair are consistent with impaired arterial perfusion to the foot. When ischemia is recognized as contributing to pedal ulceration and infection in the diabetic foot, quantitation of its severity may be difficult. Standard clinical evaluation of trophic changes is limited in an infected foot with its accompanying swelling, edema, and erythema. A palpable pedal pulse does not preclude the possibility of the presence of limb-threatening ischemia. Additional non-invasive vascular studies should be undertaken for these patients. Management of the diabetic foot is often a complex clinical problem. However, the principles of care are simple, including correction of systemic factors, such as blood glucose control, cardiovascular risk factor management, and smoking, as well as local factor correction, such as debridement, pressure relief, infection control, and revascularization when indicated. When a patient presents with evidence of infection, adequate drainage and antibiotic therapy are mandatory. The next step should be performed to differentiate the more common neuropathic ulcerations from the truly ischemic ulceration. Symptoms of rest pain or claudication are not often helpful because many of these patients are asymptomatic as a result of the presence of their neuropathy and inactivity. If an infected foot requires debridement or open partial forefoot amputation, observing the wound on a daily base is also important. Once infection is eradicated, there should be prompt signs of healing, including the development of wound granulation within several days. If wounds are not showing signs of prompt healing, arteriography is necessary. Early aggressive drainage, debridement, and local foot amputations combined with liberal use of revascularization results in cumulative limb salvage of 74% at 5 years in high-risk groups. Others report that pedal bypass to the ischemic infected foot is effective and safe as long as infection adequately controlled. These studies strongly suggest that early recognition and aggressive surgical drainage of pedal sepsis followed by surgical revascularization is critical to achieving maximal limb salvage in the high-risk population. Patients who have diabetes present a unique challenge in lower extremity revascularization because of the distal origination of many bypasses, distal distribution of the occlusive disease, and the frequently calcified arterial wall. An aggressive multidisciplinary approach to foot disease associated with diabetes involving the primary care provider, medical specialists, interventional radiology, and podiatric, plastic, and vascular surgeons will provide optimal medical and surgical care. Peripheral vascular disease is highly treatable if intervention is instituted in a timely and collegial fashion.
Arteries↗
Antisense basic fibroblast growth factor alters the time course of mitogen-activated protein kinase in arterialized vein graft remodeling.
PURPOSE: Neointimal hyperplasia (NIH) is complete by 3 weeks in rabbit vein grafts implanted into the arterial circulation. Activation of the mitogen-activated protein kinase (MAPK) family of protein kinases is thought to be critical in remodeling events such as cellular proliferation, differentiation, and migration, as found in NIH. We previously demonstrated that antisense basic fibroblast growth factor (ASbFGF) inhibited the synthesis of basic fibroblast growth factor (bFGF) in the balloon injury model of NIH. We examined the effect of ASbFGF on NIH and the time course of MAPK, extracellular signal-regulated kinase (ERK) 1/2, c-Jun N-terminal protein kinase (JNK), and p38 kinase activation in arterialized vein grafts. METHODS: Carotid interposition of a vein bypass graft was performed in 75 New Zealand White rabbits. Segments of the external jugular vein were transfected with a replication-deficient adenovirus containing the messenger RNA sequence for rat ASbFGF at 1 x 10(10) plaque-forming units per milliliter; control animals were given phosphate-buffered saline solution (PBS) alone. Rabbits were killed at 30 minutes, 4 days, 7 days, and 21 days (n = 8). Four grafts in each group were fixed with formalin and embedded in paraffin, then processed with elastin-collagen and hematoxylin-eosin stains. The other four grafts were individually frozen, and total protein was extracted. Phosphorylation of MAPK, ERK1/2, JNK, and p38, was determined with Western blot analysis and immunohistochemistry. Groups were compared with analysis of variance. RESULTS: The thickness of neointima in the PBS group and the ASbFGF group at 21 days was 60.2 +/- 2.1 and 39.4 +/- 2.1 microm, respectively (P <.01). In both the control and ASbFGF groups, all 3 MAPKs demonstrated activation compared with preimplantation levels. However, when compared with the PBS group the ASbFGF group showed greater than 33% inhibition of all three MAPKs by day 4 and day 7 (P <.05), but no significant difference in any MAPK activation by day 21 (P >.05, all groups). Cells staining positive for activated MAPK were found in the neointima and adventitia of vein grafts in both the PBS and ASbFGF groups. CONCLUSION: MAPKs are activated during the first week after vein graft implantation. Grafts treated with ASbFGF demonstrated reduced MAPK activation and less neointimal thickening. These results suggest that the process of vein graft adaptation to the arterial circulation, and subsequent NIH, may depend on basic fibroblast growth factor activity, which is mediated, at least in part, by a MAPK-dependent mechanism.
Animals↗
Modulation of vascular smooth muscle cell alignment by cyclic strain is dependent on reactive oxygen species and P38 mitogen-activated protein kinase.
PURPOSE: The aim of this study was to investigate the molecular targets of reactive oxygen species (ROS) and to determine whether cyclic strain induces smooth muscle cell (SMC) alignment via the ROS system. We assessed stretch-induced nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase activation and the redox sensitivity of cyclic strain-stimulated activation of the mitogen-activated protein kinase (MAPK) family. METHODS: SMCs were seeded on flexible collagen I-coated plates and exposed to cyclic strain. NAD(P)H oxidase activation was measured with lucigenin-enhanced chemiluminescent detection of superoxide. Activation of MAPK was detected by determining phosphorylation of extracellular signal-regulated protein kinase (ERK1/2), c-jun N-terminal kinase (JNK1/2), and p38 MAPK with immunoblotting. In other experiments, SMCs were exposed to diphenylene iodonium (DPI), an NAD(P)H inhibitor, 30 minutes before stretch. MAPK activation and cell orientation were then assessed. RESULTS: Cyclic strain elicits a rapid increase in intracellular NADH/NADPH oxidase in SMCs. There was also a rapid and robust phosphorylation of ERK1/2, JNK1/2, and p38 MAPK. Cyclic strain-induced intracellular NAD(P)H generation was almost completely blocked with DPI. DPI also inhibited the strain-induced phosphorylation of ERK1/2, JNK1/2, and p38 MAPK. Both the p38 MAPK specific inhibitor, SB 202190, and DPI blocked cyclic strain-induced cell alignment, but PD98059, an ERK1/2-specific inhibitor, and SP600125, an anthrazolone inhibitor of JNK, did not. CONCLUSION: Our results provide evidence that p38 MAPK is a critical component of the oxidant stress ROS-sensitive signaling pathway and plays a crucial role in vascular alignment induced by cyclic stain.
Animals↗
Shear stress and cyclic strain may suppress apoptosis in endothelial cells by different pathways.
Endothelial cells (ECs) are exposed to hemodynamic forces such as shear stress (SS) and cyclic strain (CS) in vivo. Alterations in these forces may stimulate EC growth and intimal hyperplasia, possibly by promotion of cell survival through inhibition of apoptosis. The authors examined the effect of SS and CS on inhibition of apoptosis and phosphorylation of Akt and its downstream target Bad in bovine aortic ECs in vitro. Arterial levels of laminar SS (14 dyne/cm(2)) or CS (10%) suppressed apoptosis due to serum withdrawal in EC; this suppression due to SS or CS was completely inhibited by phosphatidylinositol 3'-kinase (PI3K) inhibition. Phosphorylation of Akt in EC exposed to SS or CS was time dependent but with maximal stimulation at 30 min (SS) or 5 min (CS); SS- or CS-induced Akt phosphorylation was inhibited in the presence of PI3K inhibition. SS-induced, but not CS-induced, phosphorylation of Bad was inhibited by PI3K inhibition. These results suggest that hemodynamic forces suppress apoptosis in ECs via phosphorylation of Akt and that SS and CS differentially activate the downstream phosphorylation of Bad, possibly by stimulating an alternate pathway. This suggests an additional mechanism by which hemodynamic forces can differentially regulate transcription in ECs, and thereby possibly maintain the viability of normal endothelium.
Animals↗
Abdominal aortic aneurysm in association with a congenital pelvic horseshoe kidney: sentinel report and technical consideration.
A case of an abdominal aortic aneurysm in the presence of a congenital pelvic horseshoe kidney is described and the technical approach discussed. Renal function was preserved by 'double clamping' during the proximal anastomosis and infusing cold crystalloid into cannulated renal arteries originating from the aneurysm sac.
Abnormalities, Multiple↗