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Elmarasi M, Elmakaty I, Elsayed B, Elsayed A, Zein JA, Boudaka A, Eid AH. Phenotypic switching of vascular smooth muscle cells in atherosclerosis, hypertension, and aortic dissection. J Cell Physiol 2024; 239:e31200. [PMID: 38291732 DOI: 10.1002/jcp.31200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/12/2023] [Accepted: 01/16/2024] [Indexed: 02/01/2024]
Abstract
Vascular smooth muscle cells (VSMCs) play a critical role in regulating vasotone, and their phenotypic plasticity is a key contributor to the pathogenesis of various vascular diseases. Two main VSMC phenotypes have been well described: contractile and synthetic. Contractile VSMCs are typically found in the tunica media of the vessel wall, and are responsible for regulating vascular tone and diameter. Synthetic VSMCs, on the other hand, are typically found in the tunica intima and adventitia, and are involved in vascular repair and remodeling. Switching between contractile and synthetic phenotypes occurs in response to various insults and stimuli, such as injury or inflammation, and this allows VSMCs to adapt to changing environmental cues and regulate vascular tone, growth, and repair. Furthermore, VSMCs can also switch to osteoblast-like and chondrocyte-like cell phenotypes, which may contribute to vascular calcification and other pathological processes like the formation of atherosclerotic plaques. This provides discusses the mechanisms that regulate VSMC phenotypic switching and its role in the development of vascular diseases. A better understanding of these processes is essential for the development of effective diagnostic and therapeutic strategies.
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Affiliation(s)
- Mohamed Elmarasi
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Ibrahim Elmakaty
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Basel Elsayed
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Abdelrahman Elsayed
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Jana Al Zein
- Faculty of Medical Sciences, Lebanese University, Hadath, Beirut, Lebanon
| | - Ammar Boudaka
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Ali H Eid
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
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Fujita S, Honda K, Yamaguchi M, Fukuzo S, Saneyasu T, Kamisoyama H. Role of Insulin-like Growth Factor-1 in the Central Regulation of Feeding Behavior in Chicks. J Poult Sci 2019; 56:270-276. [PMID: 32055224 PMCID: PMC7005399 DOI: 10.2141/jpsa.0180127] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 01/17/2019] [Indexed: 12/15/2022] Open
Abstract
Insulin-like growth factor-1 (IGF-1) is a key regulator of muscle development and metabolism in chickens. Recently, we have demonstrated that intracerebroventricular administration of IGF-1 significantly decreased food intake in broiler chicks. However, the molecular mechanisms underlying the IGF-1-induced anorexia and the anorexigenic effect of IGF-1 in different strains of commercial chicks have not been investigated. Neuropeptide Y (NPY, a hypothalamic orexigenic neuropeptide), agouti-related protein (AgRP, a hypothalamic orexigenic neuropeptide), and proopiomelanocortin (POMC, the precursor of hypothalamic anorexigenic neuropeptides) play important roles in the regulation of food intake in both mammals and chickens. Evidence shows that several cell signaling pathways in the hypothalamus are involved in regulating the feeding behavior of mammals. In the present study, we first investigated the effects of IGF-1 on the expression of appetite-regulating neuropeptides and phosphorylation of signaling molecules in the hypothalamus of broiler chicks. Intracerebroventricular administration of IGF-1 significantly increased the mRNA levels of POMC, whereas the mRNA levels of NPY and AgRP were not significantly altered. IGF-1 also significantly induced the phosphorylation of v-Akt murine thymoma viral oncogene homolog 1 (AKT) in the hypothalamus of chicks, but did not influence the phosphorylation of forkhead box O1, S6 protein, AMP-activated protein kinase, and extracellular signal-regulated kinase 1/2. We also compared the effect of IGF-1 on food intake in broiler chicks (a hyperphagic strain of chickens) and layer chicks. Results demonstrated that the threshold of IGF-1-induced anorexia in broiler chicks was higher than that in layer chicks. Our observations suggest that hypothalamic POMC and AKT may be involved in the IGF-1-induced anorexigenic pathway and that high threshold of IGF-1-induced anorexia in broiler chicks might be one of the causes of hyperphagia in broiler chicks. Overall, it appears that IGF-1 plays important roles in the central regulation of feeding behavior in chicks.
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Affiliation(s)
- Shoichi Fujita
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Kazuhisa Honda
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Mika Yamaguchi
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Satoshi Fukuzo
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Takaoki Saneyasu
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Hiroshi Kamisoyama
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
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Xi G, Wai C, Clemmons D. Inhibition of Aberrant IGF-I Signaling in Diabetic Male Rat Retina Prevents and Reverses Changes of Diabetic Retinopathy. J Diabetes Res 2019; 2019:6456032. [PMID: 31049357 PMCID: PMC6458945 DOI: 10.1155/2019/6456032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/23/2018] [Indexed: 12/18/2022] Open
Abstract
Hyperglycemia results in inhibition of cleavage of integrin-associated protein (IAP) thereby allowing it to bind to SHPS-1 which results in pathophysiologic changes in endothelial function. This study determined if an anti-rat IAP antibody directed against the SHPS-1 binding site which disrupts IAP/SHPS-1 association could inhibit these pathophysiologic changes. The anti-IAP antibody inhibited IGF-I-stimulated SHPS-1, p52Shc, MAP kinase phosphorylation, and proliferation in endothelial cells. To determine if it could reverse established pathophysiologic changes in vivo, this antibody or normal rat IgG F(ab)2 was injected intraperitoneally for 6 weeks into rats that had diabetes for 4 weeks. Optical coherence tomography (OCT) showed that retinal thickness increased at 4 weeks and this increase was maintained in rats treated with the control antibody for an additional 6 weeks. The increase was reversed by anti-IAP antibody treatment (84.6 ± 2.0 compared to 92.3 ± 2.5 μm, p < 0.01). This value was similar to nondiabetic animals (82.2 ± 1.6 μm, p, NS). The anti-IAP antibody also decreased retinal vascular permeability (0.62 ± 0.12 vs. 0.96 ± 0.25%/g/h, p < 0.001). To determine if it was effective after local injection, this antibody or control was administered via intravitreal injection. After 3 weeks, retinal thickness increased to 6.4 ± 2.8% in diabetic rats, and IAP antibody treatment prevented this increase (0.8 ± 2.5%, p < 0.01). It also prevented the increase of retinal vascular permeability (0.92 ± 0.62 vs. 1.63 ± 0.99%/g/h, p < 0.001). Biochemical analyses of retinal extracts showed that the anti-IAP antibody inhibited IAP/SHPS-1 association and SHPS-1 phosphorylation. This resulted in inhibition of AKT activation and VEGF synthesis in the retina: changes associated with increased vascular permeability. We conclude the anti-rat IAP antibody disrupts IAP/SHPS-1 association and attenuates aberrant IGF-I signaling thereby preventing or reversing the progression of retinal pathophysiological changes.
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Affiliation(s)
- Gang Xi
- Division of Endocrinology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill NC 27599, USA
| | - Christine Wai
- Division of Endocrinology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill NC 27599, USA
| | - David Clemmons
- Division of Endocrinology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill NC 27599, USA
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Xi G, Shen X, Wai C, White MF, Clemmons DR. Hyperglycemia induces vascular smooth muscle cell dedifferentiation by suppressing insulin receptor substrate-1-mediated p53/KLF4 complex stabilization. J Biol Chem 2018; 294:2407-2421. [PMID: 30578299 DOI: 10.1074/jbc.ra118.005398] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 12/10/2018] [Indexed: 01/01/2023] Open
Abstract
Hyperglycemia and insulin resistance accelerate atherosclerosis by an unclear mechanism. The two factors down-regulate insulin receptor substrate-1 (IRS-1), an intermediary of the insulin/IGF-I signaling system. We previously reported that IRS-1 down-regulation leads to vascular smooth muscle cell (VSMC) dedifferentiation and that IRS-1 deletion from VSMCs in normoglycemic mice replicates this response. However, we did not determine IRS-1's role in mediating differentiation. Here, we sought to define the mechanism by which IRS-1 maintains VSMC differentiation. High glucose or IRS-1 knockdown decreased p53 levels by enhancing MDM2 proto-oncogene (MDM2)-mediated ubiquitination, resulting in decreased binding of p53 to Krüppel-like factor 4 (KLF4). Exposure to nutlin-3, which dissociates MDM2/p53, decreased p53 ubiquitination and enhanced the p53/KLF4 association and differentiation marker protein expression. IRS-1 overexpression in high glucose inhibited the MDM2/p53 association, leading to increased p53 and p53/KLF4 levels, thereby increasing differentiation. Nutlin-3 treatment of diabetic or Irs1 -/- mice enhanced p53/KLF4 and the expression of p21, smooth muscle protein 22 (SM22), and myocardin and inhibited aortic VSMC proliferation. Injecting normoglycemic mice with a peptide disrupting the IRS-1/p53 association reduced p53, p53/KLF4, and differentiation. Analyzing atherosclerotic lesions in hypercholesterolemic, diabetic pigs, we found that p53, IRS-1, SM22, myocardin, and KLF4/p53 levels are significantly decreased compared with their expression in nondiabetic pigs. We conclude that IRS-1 is critical for maintaining VSMC differentiation. Hyperglycemia- or insulin resistance-induced IRS-1 down-regulation decreases the p53/KLF4 association and enhances dedifferentiation and proliferation. Our results suggest that enhancing IRS-1-dependent p53 stabilization could attenuate the progression of atherosclerotic lesions in hyperglycemia and insulin-resistance states.
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Affiliation(s)
- Gang Xi
- From the Division of Endocrinology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - Xinchun Shen
- the College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China, and
| | - Christine Wai
- From the Division of Endocrinology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - Morris F White
- the Division of Endocrinology, Department of Medicine, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - David R Clemmons
- From the Division of Endocrinology, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599,
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Fujita S, Honda K, Hiramoto D, Gyu M, Okuda M, Nakayama S, Yamaguchi M, Saneyasu T, Kamisoyama H. Central and peripheral administrations of insulin-like growth factor-1 suppress food intake in chicks. Physiol Behav 2017; 179:308-312. [DOI: 10.1016/j.physbeh.2017.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 06/20/2017] [Accepted: 07/01/2017] [Indexed: 11/25/2022]
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Abstract
Cardiovascular disease is the principal cause of death in patients with type 2 diabetes (T2DM). Exposure of the vasculature to metabolic disturbances leaves a persistent imprint on vascular walls, and specifically on smooth muscle cells (SMC) that favours their dysfunction and potentially underlies macrovascular complications of T2DM. Current diabetes therapies and continued development of newer treatments has led to the ability to achieve more efficient glycaemic control. There is also some evidence to suggest that some of these treatments may exert favourable pleiotropic effects, some of which may be at the level of SMC. However, emerging interest in epigenetic markers as determinants of vascular disease, and a putative link with diabetes, opens the possibility for new avenues to develop robust and specific new therapies. These will likely need to target cell-specific epigenetic changes such as effectors of DNA histone modifications that promote or inhibit gene transcription, and/or microRNAs capable of regulating entire cellular pathways through target gene repression. The growing epidemic of T2DM worldwide, and its attendant cardiovascular mortality, dictates a need for novel therapies and personalised approaches to ameliorate vascular complications in this vulnerable population.
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Affiliation(s)
- Karen E Porter
- Division of Cardiovascular & Diabetes Research, Leeds Institute of Cardiovascular & Metabolic Medicine (LICAMM) and Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Leeds, LS2 9JT, UK,
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Xi G, Shen X, Wai C, Vilas CK, Clemmons DR. Hyperglycemia stimulates p62/PKCζ interaction, which mediates NF-κB activation, increased Nox4 expression, and inflammatory cytokine activation in vascular smooth muscle. FASEB J 2015; 29:4772-82. [PMID: 26231202 DOI: 10.1096/fj.15-275453] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 07/20/2015] [Indexed: 12/20/2022]
Abstract
Hyperglycemia leads to vascular smooth muscle cell (VSMC) dedifferentiation and enhances responses to IGF-I. Prior studies showed that hyperglycemia stimulated NADPH oxidase 4 (Nox4) synthesis, and IGF-I facilitated its recruitment to a signaling complex where it oxidized src, leading to AKT and MAPK activation. To determine the mechanism that led to these changes, we analyzed the roles of p62 (sequestrosome1) and PKCζ. Hyperglycemia induced a 4.9 ± 1.0-fold increase in p62/PKCζ association, and disruption of PKCζ/p62 using a peptide inhibitor or p62 knockdown reduced PKCζ activation (78 ± 6%). 3-Phosphoinoside-dependent protein kinase 1 was also recruited to the p62 complex and directly phosphorylated PKCζ, leading to its activation (3.1 ± 0.4-fold). Subsequently, activated PKCζ phosphorylated p65 rel, which led to increased Nox4 synthesis. Studies in diabetic mice confirmed these findings (6.0 ± 0.4-fold increase in p62/PKCζ) and their disruption of attenuated Nox4 synthesis (76 ± 9% reduction). PKCζ/p62 activation stimulated inflammatory cytokine production and enhanced IGF-I-stimulated VSMC proliferation. These results define the molecular mechanism by which PKCζ is activated in response to hyperglycemia and suggest that this could be a mechanism by which other stimuli such as cytokines or metabolic stress function to stimulate NF-κB activation, thereby altering VSMC sensitivity to IGF-I.
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Affiliation(s)
- Gang Xi
- *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China
| | - Xinchun Shen
- *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China
| | - Christine Wai
- *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China
| | - Caroline K Vilas
- *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China
| | - David R Clemmons
- *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China
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El-Ashmawy NE, Khalil RM. A review on the role of L-carnitine in the management of tamoxifen side effects in treated women with breast cancer. Tumour Biol 2013; 35:2845-55. [PMID: 24338689 DOI: 10.1007/s13277-013-1477-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 11/26/2013] [Indexed: 12/20/2022] Open
Abstract
L-carnitine is an antioxidant and is found to be a protective agent against many diseases including cancer. This review illustrates the possible role of L-carnitine as an add-on therapy to breast cancer patients maintained on tamoxifen. The objectives of carnitine treatment are diverse: improving tamoxifen-related side effects, offering better cancer prognosis by reducing the risk of developing cancer recurrence or metastasis, and modulating the growth factors which may be, in part, a prospective illustration to overcome tamoxifen resistance. So, it could be recommended to supplement L-carnitine to breast cancer patients starting tamoxifen treatment.
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Affiliation(s)
- Nahla E El-Ashmawy
- Biochemistry Department, Faculty of Pharmacy, Tanta University, Tanta, Egypt
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Kou X, Han Y, Yang D, Liu Y, Fu J, Zheng S, He D, Zhou L, Zeng C. Dopamine d(1)-like receptors suppress proliferation of vascular smooth muscle cell induced by insulin-like growth factor-1. Clin Exp Hypertens 2013; 36:140-7. [PMID: 23713966 DOI: 10.3109/10641963.2013.789048] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Proliferation of vascular smooth muscle cells (VSMCs) participates in the pathogenesis and development of cardiovascular diseases, including essential hypertension and atherosclerosis. Our previous study found that stimulation of D1-like dopamine receptors inhibited insulin-induced proliferation of VSMCs. Insulin-like growth factor-1 (IGF-1) and insulin share similar structure and biological effect. However, whether or not there is any effect of D1-like receptors on IGF-1-induced proliferation of VSMCs is not known. Therefore, we investigated the inhibitory effect of D1-like dopamine receptors on the IGF-1-induced VSMCs proliferation in this study. METHOD VSMC proliferation was determined by [(3)H]-thymidine incorporation, the uptake of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and cell number. Phosphorylated/non-phosphorylated IGF-1 receptor, Akt, mTOR and p70S6K expressions were determined by immunoblotting. The oligodeoxynucleotides were transfected to A10 cells to identify the effect of D1 and D5 receptors, respectively. RESULTS IGF-1 increased the proliferation of VSMCs, while in the presence of fenoldopam, IGF-1-mediated stimulatory effect was reduced. Use of either antisense for D1 or D5 receptor partially inhibited the fenoldopam-induced antiproliferation effect of VSMCs. Use of both D1 and D5 receptor antisenses completely blocked the inhibitory effect of fenoldopam. In the presence of PI3k and mTOR inhibitors, the IGF-1-mediated proliferation of VSMCs was blocked. Moreover, IGF-1 increased the phosphorylation of PI3k and mTOR. The inhibitory effect of fenoldopam on VSMC proliferation might be due to the inhibition of IGF-1 receptor expression and IGF-1 phosphorylation, because in the presence of fenoldopam, the stimulatory effect of IGF-1 on phosphorylation of IGF-1 receptor, PI3k and mTOR is reduced, the IGF-1 receptor expression was reduced in A10 cells. CONCLUSION Activation of the D1-like receptors suppressed the proliferative effect of IGF-1 in A10 cells via the inhibition of the IGF-1R/Akt/mTOR/p70S6K pathway and downregulated the expression of IGF-1 receptor.
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Affiliation(s)
- Xun Kou
- Department of Cardiology, Daping Hospital, The Third Military Medical University , Chongqing , P.R. China and
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Zhou J, Li YS, Nguyen P, Wang KC, Weiss A, Kuo YC, Chiu JJ, Shyy JY, Chien S. Regulation of vascular smooth muscle cell turnover by endothelial cell-secreted microRNA-126: role of shear stress. Circ Res 2013; 113:40-51. [PMID: 23603512 DOI: 10.1161/circresaha.113.280883] [Citation(s) in RCA: 202] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Endothelial microRNA-126 (miR-126) modulates vascular development and angiogenesis. However, its role in the regulation of smooth muscle cell (SMC) function is unknown. OBJECTIVE To elucidate the role of miR-126 secreted by endothelial cells (ECs) in regulating SMC turnover in vitro and in vivo, as well as the effects of shear stress on the regulation. METHODS AND RESULTS Coculture of SMCs with ECs or treatment of SMCs with conditioned media from static EC monoculture (EC-CM) increased SMC miR-126 level and SMC turnover; these effects were abolished by inhibition of endothelial miR-126 and by the application of laminar shear stress to ECs. SMC miR-126 did not increase when treated with EC-CM from ECs subjected to inhibition of miR biogenesis, or with CM from sheared ECs. Depletion of extracellular/secreted vesicles in EC-CM did not affect the increase of SMC miR-126 by EC-CM. Biotinylated miR-126 or FLAG (DYKDDDDK epitope)-tagged Argonaute2 transfected into ECs was detected in the cocultured or EC-CM-treated SMCs, indicating a direct EC-to-SMC transmission of miR-126 and Argonaute2. Endothelial miR-126 represses forkhead box O3, B-cell lymphoma 2, and insulin receptor substrate 1 mRNAs in the cocultured SMCs, suggesting the functional roles of the transmitted miR-126. Systemic depletion of miR-126 in mice inhibited neointimal lesion formation of carotid arteries induced by cessation of blood flow. Administration of EC-CM or miR-126 mitigated the inhibitory effect. CONCLUSIONS Endothelial miR-126 acts as a key intercellular mediator to increase SMC turnover, and its release is reduced by atheroprotective laminar shear stress.
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Affiliation(s)
- Jing Zhou
- Department of Bioengineering and Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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Li H, Peng W, Zhuang J, Lu Y, Jian W, Wei Y, Li W, Xu Y. Vaspin attenuates high glucose-induced vascular smooth muscle cells proliferation and chemokinesis by inhibiting the MAPK, PI3K/Akt, and NF-κB signaling pathways. Atherosclerosis 2013; 228:61-8. [PMID: 23497782 DOI: 10.1016/j.atherosclerosis.2013.02.013] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Revised: 02/06/2013] [Accepted: 02/13/2013] [Indexed: 11/28/2022]
Abstract
BACKGROUND Vaspin has insulin-sensitizing effects, as well as additional beneficial effects on metabolic diseases. However, little is known about the direct effects of vaspin on vascular complications mediated by diabetes. The objective of this study is to determine the efficacy and mechanism of vaspin on hyperglycemia-induced vascular smooth muscle cells (VSMCs) proliferation, chemokinesis and cell signaling. METHODS Rat VSMCs proliferation was determined with 5-ethynyl-2'-deoxyuridine cell proliferation assays, chemokinesis was monitored with scratch assays, and reactive oxygen species (ROS) production was assessed using H2DCFDA and SOD-inhibited reduction of ferricytochrome c assay. Luciferase activity is assayed using a Dual Luciferase Reporter Assay System. Cell signaling is assessed by immunoblotting. RESULTS Vaspin significantly inhibited VSMCs proliferation and chemokinesis, as well as ROS generation and NADPH oxidase activity, induced by high glucose (HG) treatment. Compared with HG, vaspin significantly decreased VSMCs proliferation by 40 ± 8% at 100 ng/ml. Vaspin also decreased ROS production by 16 ± 8% at 100 ng/ml and 30 ± 8% at 300 ng/ml (all P < 0.01). Vaspin significantly abolished HG-induced phosphorylation of oxidase subunits p47phox, Akt, p38, and JNK1/2 without affecting their total levels, and attenuated HG-induced phosphorylation of insulin receptor and its downstream IRS-1 and IRS-2. For downstream targets, NF-κB activity and IκBα phosphorylation were both enhanced significantly after HG stimulation, and these effects were inhibited by vaspin. Vaspin also significantly abolished HG-induced PCNA and cyclin D1 expression. CONCLUSIONS Vaspin inhibits HG-induced VSMCs proliferation and chemokinesis by preventing ROS activation and MAPK, PI3K/Akt, and NF-κB signaling.
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Affiliation(s)
- Hailing Li
- Department of Cardiology, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, 301 Middle Yanchang Road, Shanghai 200072, China
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Rowland M, Fontana W, Deeds E. Crosstalk and competition in signaling networks. Biophys J 2012; 103:2389-98. [PMID: 23283238 PMCID: PMC3514525 DOI: 10.1016/j.bpj.2012.10.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/02/2012] [Accepted: 10/10/2012] [Indexed: 12/26/2022] Open
Abstract
Signaling networks have evolved to transduce external and internal information into critical cellular decisions such as growth, differentiation, and apoptosis. These networks form highly interconnected systems within cells due to network crosstalk, where an enzyme from one canonical pathway acts on targets from other pathways. It is currently unclear what types of effects these interconnections can have on the response of networks to incoming signals. In this work, we employ mathematical models to characterize the influence that multiple substrates have on one another. These models build off of the atomistic motif of a kinase/phosphatase pair acting on a single substrate. We find that the ultrasensitive, switch-like response these motifs can exhibit becomes transitive: if one substrate saturates the enzymes and responds ultrasensitively, then all substrates will do so regardless of their degree of saturation. We also demonstrate that the phosphatases themselves can induce crosstalk even when the kinases are independent. These findings have strong implications for how we understand and classify crosstalk, as well as for the rational development of kinase inhibitors aimed at pharmaceutically modulating network behavior.
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Affiliation(s)
| | - Walter Fontana
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts
| | - Eric J. Deeds
- Center for Bioinformatics, University of Kansas, Lawrence, Kansas
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
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Insulin-like growth factor (IGF) binding protein 2 functions coordinately with receptor protein tyrosine phosphatase β and the IGF-I receptor to regulate IGF-I-stimulated signaling. Mol Cell Biol 2012; 32:4116-30. [PMID: 22869525 DOI: 10.1128/mcb.01011-12] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Insulin-like growth factor I (IGF-I) is a mitogen for vascular smooth muscle cells (VSMC) and has been implicated in the development and progression of atherosclerosis. IGF binding proteins (IGFBPs) modify IGF-I actions independently of IGF binding, but a receptor-based mechanism by which they function has not been elucidated. We investigated the role of IGFBP-2 and receptor protein tyrosine phosphatase β (RPTPβ) in regulating IGF-I signaling and cellular proliferation. IGFBP-2 bound RPTPβ, which led to its dimerization and inactivation. This enhanced PTEN tyrosine phosphorylation and inhibited PTEN activity. Utilization of substrate trapping and phosphatase-dead mutants showed that RPTPβ bound specifically to PTEN and dephosphorylated it. IGFBP-2 knockdown led to decreased PTEN tyrosine phosphorylation and decreased AKT Ser473 activation. IGFBP-2 enhanced IGF-I-stimulated VSMC migration and proliferation. Analysis of aortas obtained from IGFBP-2(-/-) mice showed that RPTPβ was activated, and this was associated with inhibition of IGF-I stimulated AKT Ser473 phosphorylation and VSMC proliferation. These changes were rescued following administration of IGFBP-2. These findings present a novel mechanism for coordinate regulation of IGFBP-2 and IGF-I signaling functions that lead to stimulation of VSMC proliferation. The results have important implications for understanding how IGFBPs modulate the cellular response to IGF-I.
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Radhakrishnan Y, Shen X, Maile LA, Xi G, Clemmons DR. IGF-I stimulates cooperative interaction between the IGF-I receptor and CSK homologous kinase that regulates SHPS-1 phosphorylation in vascular smooth muscle cells. Mol Endocrinol 2011; 25:1636-49. [PMID: 21799000 DOI: 10.1210/me.2011-0035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
IGF-I plays an important role in smooth muscle cell proliferation and migration. In vascular smooth muscle cells cultured in 25 mm glucose, IGF-I stimulated a significant increase in Src homology 2 domain containing protein tyrosine phosphatase substrate-1 (SHPS-1) phosphorylation compared with 5 mm glucose and this increase was required for smooth muscle cell proliferation. A proteome-wide screen revealed that carboxyl-terminal SRC kinase homologous kinase (CTK) bound directly to phosphotyrosines in the SHPS-1 cytoplasmic domain. Because the kinase(s) that phosphorylates these tyrosines in response to IGF-I is unknown, we determined the roles of IGF-I receptor (IGF-IR) and CTK in mediating SHPS-1 phosphorylation. After IGF-I stimulation, CTK was recruited to IGF-IR and subsequently to phospho-SHPS-1. Expression of an IGF-IR mutant that eliminated CTK binding reduced CTK transfer to SHPS-1, SHPS-1 phosphorylation, and cell proliferation. IGF-IR phosphorylated SHPS-1, which provided a binding site for CTK. CTK recruitment to SHPS-1 resulted in a further enhancement of SHPS-1 phosphorylation. CTK knockdown also impaired IGF-I-stimulated SHPS-1 phosphorylation and downstream signaling. Analysis of specific tyrosines showed that mutation of tyrosines 428/452 in SHPS-1 to phenylalanine reduced SHPS-1 phosphorylation but allowed CTK binding. In contrast, the mutation of tyrosines 469/495 inhibited IGF-IR-mediated the phosphorylation of SHPS-1 and CTK binding, suggesting that IGF-IR phosphorylated Y469/495, allowing CTK binding, and that CTK subsequently phosphorylated Y428/452. Based on the above findings, we conclude that after IGF-I stimulation, CTK is recruited to IGF-IR and its recruitment facilitates CTK's subsequent association with phospho-SHPS-1. This results in the enhanced CTK transfer to SHPS-1, and the two kinases then fully phosphorylate SHPS-1, which is necessary for IGF-I stimulated cellular proliferation.
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Affiliation(s)
- Yashwanth Radhakrishnan
- Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina 27599, USA
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15
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Zhao Y, Biswas SK, McNulty PH, Kozak M, Jun JY, Segar L. PDGF-induced vascular smooth muscle cell proliferation is associated with dysregulation of insulin receptor substrates. Am J Physiol Cell Physiol 2011; 300:C1375-85. [PMID: 21325637 DOI: 10.1152/ajpcell.00670.2008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In vascular smooth muscle cells (VSMCs), platelet-derived growth factor (PDGF) plays a major role in inducing phenotypic switching from contractile to proliferative state. Importantly, VSMC phenotypic switching is also determined by the phosphorylation state/expression levels of insulin receptor substrate (IRS), an intermediary signaling component that is shared by insulin and IGF-I. To date, the roles of PDGF-induced key proliferative signaling components including Akt, p70S6kinase, and ERK1/2 on the serine phosphorylation/expression of IRS-1 and IRS-2 isoforms remain unclear in VSMCs. We hypothesize that PDGF-induced VSMC proliferation is associated with dysregulation of insulin receptor substrates. Using human aortic VSMCs, we demonstrate that prolonged PDGF treatment led to sustained increases in the phosphorylation of protein kinases such as Akt, p70S6kinase, and ERK1/2, which mediate VSMC proliferation. In addition, PDGF enhanced IRS-1/IRS-2 serine phosphorylation and downregulated IRS-2 expression in a time- and concentration-dependent manner. Notably, phosphoinositide 3-kinase (PI 3-kinase) inhibitor (PI-103) and mammalian target of rapamycin inhibitor (rapamycin), which abolished PDGF-induced Akt and p70S6kinase phosphorylation, respectively, blocked PDGF-induced IRS-1 serine phosphorylation and IRS-2 downregulation. In contrast, MEK1/ERK inhibitor (U0126) failed to block PDGF-induced IRS-1 serine phosphorylation and IRS-2 downregulation. PDGF-induced IRS-2 downregulation was prevented by lactacystin, an inhibitor of proteasomal degradation. Functionally, PDGF-mediated IRS-1/IRS-2 dysregulation resulted in the attenuation of insulin-induced IRS-1/IRS-2-associated PI 3-kinase activity. Pharmacological inhibition of PDGF receptor tyrosine kinase with imatinib prevented IRS-1/IRS-2 dysregulation and restored insulin receptor signaling. In conclusion, strategies to inhibit PDGF receptors would not only inhibit neointimal growth but may provide new therapeutic options to prevent dysregulated insulin receptor signaling in VSMCs in nondiabetic and diabetic states.
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Affiliation(s)
- Yan Zhao
- Departments of Medicine and Pharmacology, Heart & Vascular Institute, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
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16
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Cecchettini A, Rocchiccioli S, Boccardi C, Citti L. Vascular smooth-muscle-cell activation: proteomics point of view. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 288:43-99. [PMID: 21482410 DOI: 10.1016/b978-0-12-386041-5.00002-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Vascular smooth-muscle cells (VSMCs) are the main component of the artery medial layer. Thanks to their great plasticity, when stimulated by external inputs, VSMCs react by changing morphology and functions and activating new signaling pathways while switching others off. In this way, they are able to increase the cell proliferation, migration, and synthetic capacity significantly in response to vascular injury assuming a more dedifferentiated state. In different states of differentiation, VSMCs are characterized by various repertories of activated pathways and differentially expressed proteins. In this context, great interest is addressed to proteomics technology, in particular to differential proteomics. In recent years, many authors have investigated proteomics in order to identify the molecular factors putatively involved in VSMC phenotypic modulation, focusing on metabolic networks linking the differentially expressed proteins. Some of the identified proteins may be markers of pathology and become useful tools of diagnosis. These proteins could also represent appropriately validated targets and be useful either for prevention, if related to early events of atherosclerosis, or for treatment, if specific of the acute, mid, and late phases of the pathology. RNA-dependent gene silencing, obtained against the putative targets with high selective and specific molecular tools, might be able to reverse a pathological drift and be suitable candidates for innovative therapeutic approaches.
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Cascella T, Radhakrishnan Y, Maile LA, Busby WH, Gollahon K, Colao A, Clemmons DR. Aldosterone enhances IGF-I-mediated signaling and biological function in vascular smooth muscle cells. Endocrinology 2010; 151:5851-64. [PMID: 20881255 PMCID: PMC2999491 DOI: 10.1210/en.2010-0350] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The IGF-I pathway and renin-angiotensin-aldosterone axis are both involved in the pathogenesis of hypertension and atherosclerosis, but no information is available about IGF-I and aldosterone interaction or their potential synergistic effects in vascular smooth muscle cells (VSMCs). The aims of this study were to investigate whether aldosterone influences IGF-I signaling and to determine the mechanism(s) by which aldosterone affects IGF-I function. Aldosterone resulted in significant increases in the Akt (1.87 ± 0.24, P < 0.001), MAPK (1.78 ± 0.13, P < 0.001), p70S6kinase (1.92 ± 0.15, P < 0.001), IGF-I receptor (1.69 ± 0.05, P < 0.01), and insulin receptor substrate-1 (1.7 ± 0.04, P < 0.01) (fold increase, mean ± SEM, n = 3) phosphorylation responses to IGF-I compared with IGF-I treatment alone. There were also significant increases in VSMC proliferation, migration, and protein synthesis (1.63 ± 0.03-, 1.56 ± 0.08-, and 1.51 ± 0.04-fold increases compared with IGF-I alone, respectively, n = 3, P < 0.001). Aldosterone induced osteopontin (OPN) mRNA expression and activation of αVβ3-integrin as well as an increase in the synthesis of IGF-I receptor. The enhancing effects of aldosterone were inhibited by eplerenone (10 μmol/liter), actinomycin-D (20 nmol/liter), and an anti-αVβ3-integrin antibody that blocks OPN binding. The antioxidant N-acetylcysteine (2 mmol/liter) completely inhibited the ability of aldosterone to induce any of these changes. In conclusion, our results show that aldosterone enhances IGF-I signaling and biological actions in VSMCs through induction of OPN followed by its subsequent activation of the αVβ3-integrin and by increasing IGF-I receptor. These changes are mediated in part through increased oxidative stress. The findings suggest a new mechanism by which aldosterone could accelerate the development of atherosclerosis.
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Affiliation(s)
- Teresa Cascella
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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18
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Shen X, Xi G, Radhakrishnan Y, Clemmons DR. PDK1 recruitment to the SHPS-1 signaling complex enhances insulin-like growth factor-i-stimulated AKT activation and vascular smooth muscle cell survival. J Biol Chem 2010; 285:29416-24. [PMID: 20643654 PMCID: PMC2937974 DOI: 10.1074/jbc.m110.155325] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 07/16/2010] [Indexed: 12/16/2022] Open
Abstract
In vascular smooth muscle cells, exposed to hyperglycemia and insulin-like growth factor-I (IGF-I), SHPS-1 functions as a scaffold protein, and a signaling complex is assembled that leads to AKT activation. However, the underlying mechanism by which formation of this complex activates the kinase that phosphorylates AKT (Thr(308)) is unknown. Therefore, we investigated the mechanism of PDK1 recruitment to the SHPS-1 signaling complex and the consequences of disrupting PDK1 recruitment for downstream signaling. Our results show that following IGF-I stimulation, PDK1 is recruited to SHPS-1, and its recruitment is mediated by Grb2, which associates with SHPS-1 via its interaction with Pyk2, a component of the SHPS-1-associated complex. A proline-rich sequence in PDK1 bound to an Src homology 3 domain in Grb2 in response to IGF-I. Disruption of Grb2-PDK1 by expression of either a Grb2 Src homology 3 domain or a PDK1 proline to alanine mutant inhibited PDK1 recruitment to SHPS-1, leading to impaired IGF-I-stimulated AKT Thr(308) phosphorylation. Following its recruitment to SHPS-1, PDK1 was further activated via Tyr(373/376) phosphorylation, and this was required for a maximal increase in PDK1 kinase activity and AKT-mediated FOXO3a Thr(32) phosphorylation. PDK1 recruitment was also required for IGF-I to prevent apoptosis that occurred in response to hyperglycemia. Assembly of the Grb2-PDK1 complex on SHPS-1 was specific for IGF-I signaling because inhibiting PDK1 recruitment to SHPS-1 had no effect on EGF-stimulated AKT Thr(308) phosphorylation. These findings reveal a novel mechanism for recruitment of PDK1 to the SHPS-1 signaling complex, which is required for IGF-I-stimulated AKT Thr(308) phosphorylation and inhibition of apoptosis.
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MESH Headings
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/metabolism
- Binding Sites
- Cell Line
- Cell Survival/drug effects
- Cells, Cultured
- GRB2 Adaptor Protein/genetics
- GRB2 Adaptor Protein/metabolism
- Humans
- Immunoblotting
- Immunoprecipitation
- In Situ Nick-End Labeling
- Insulin-Like Growth Factor I/pharmacology
- Muscle, Smooth, Vascular/cytology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Phosphorylation
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Protein Transport/drug effects
- Protein Transport/genetics
- Proto-Oncogene Proteins c-akt/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Pyruvate Dehydrogenase Acetyl-Transferring Kinase
- RNA Interference
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Signal Transduction/drug effects
- Swine
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Affiliation(s)
- Xinchun Shen
- From the Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - Gang Xi
- From the Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - Yashwanth Radhakrishnan
- From the Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - David R. Clemmons
- From the Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
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