| 1. |
- Bhattachariya, Anirban, et al.
(författare)
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Expression of microRNAs is essential for arterial myogenic tone and pressure-induced activation of the PI3-kinase/Akt pathway.
- 2014
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 1755-3245 .- 0008-6363. ; 101:2, s. 288-296
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Tidskriftsartikel (refereegranskat)abstract
- The myogenic response is the intrinsic ability of small arteries to constrict in response to increased intraluminal pressure. Although microRNAs have been shown to play a role in vascular smooth muscle function, their importance in the regulation of the myogenic response is not known. In this study, we investigate the role of microRNAs in the regulation of myogenic tone by using smooth muscle-specific and tamoxifen-inducible deletion of the endonuclease Dicer in mice.
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| 2. |
- Bhattachariya, Anirban, et al.
(författare)
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PYK2 selectively mediates signals for growth versus differentiation in response to stretch of spontaneously active vascular smooth muscle.
- 2014
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Ingår i: Physiological Reports. - : Wiley. - 2051-817X. ; 2:7
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Tidskriftsartikel (refereegranskat)abstract
- Stretch of vascular smooth muscle stimulates growth and proliferation as well as contraction and expression of contractile/cytoskeletal proteins, all of which are also regulated by calcium-dependent signals. We studied the role of the calcium- and integrin-activated proline-rich tyrosine kinase 2 (PYK2) in stretch-induced responses of the rat portal vein loaded by a hanging weight ex vivo. PYK2 phosphorylation at Tyr-402 was increased both by a 10-min stretch and by organ culture with load over several days. Protein and DNA synthesis were reduced by the novel PYK2 inhibitor PF-4594755 (0.5-1 μmol/L), while still sensitive to stretch. In 3-day organ culture, PF-4594755 caused maintained myogenic spontaneous activity but did not affect contraction in response to high-K(+) (60 mmol/L) or to α1-adrenergic stimulation by cirazoline. Basal and stretch-induced PYK2 phosphorylation in culture were inhibited by PF-4594755, closely mimicking inhibition of non-voltage-dependent calcium influx by 2-APB (30 μmol/L). In contrast, the L-type calcium channel blocker, nifedipine (1 μmol/L) eliminated stretch-induced but not basal PYK2 phosphorylation. Stretch-induced Akt and ERK1/2 phosphorylation was eliminated by PF-4594755. PYK2 inhibition had no effect on mRNA expression of several smooth muscle markers, and stretch-sensitive SM22α synthesis was preserved. Culture of portal vein with the Ang II inhibitor losartan (1 μmol/L) eliminated stretch sensitivity of PYK2 and Akt phosphorylation, but did not affect mRNA expression of smooth muscle markers. The results suggest that PYK2 signaling functionally distinguishes effects of voltage- and non-voltage-dependent calcium influx. A small-molecule inhibitor of PYK2 reduces growth and DNA synthesis but does not affect contractile differentiation of vascular smooth muscle.
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| 3. |
- Dahan, Diana, et al.
(författare)
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Induction of angiotensin converting enzyme after miR-143/145 deletion is critical for impaired smooth muscle contractility.
- 2014
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Ingår i: American Journal of Physiology: Cell Physiology. - : American Physiological Society. - 1522-1563 .- 0363-6143. ; 307:12, s. 1093-1101
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Tidskriftsartikel (refereegranskat)abstract
- MicroRNAs have emerged as regulators of smooth muscle cell phenotype with a role in smooth muscle-related disease. Studies have shown that miR-143 and miR-145 are the most highly expressed microRNAs in smooth muscle cells, controlling differentiation and function. The effect of miR-143/145 knockout has been established in the vasculature but not in smooth muscle from other organs. Using knockout mice we found that maximal contraction induced by either depolarization or phosphatase inhibition was reduced in vascular and airway smooth muscle but maintained in the urinary bladder. Furthermore, a reduction of media thickness and reduced expression of differentiation markers was seen in the aorta but not in the bladder. Supporting the view that phenotype switching depends on a tissue-specific target of miR-143/145, we found induction of angiotensin converting enzyme in the aorta but not in the bladder where angiotensin converting enzyme was expressed at a low level. Chronic treatment with angiotensin type-1 receptor antagonist restored contractility in miR-143/145-deficient aorta while leaving bladder contractility unaffected. This shows that tissue-specific targets are critical for the effects of miR-143/145 on smooth muscle differentiation and that angiotensin converting enzyme is one such target.
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| 4. |
- Grossi, Mario, et al.
(författare)
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Inhibition of Polyamine Formation Antagonizes Vascular Smooth Muscle Cell Proliferation and Preserves the Contractile Phenotype.
- 2014
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - : Wiley. - 1742-7843 .- 1742-7835. ; 115:5, s. 379-388
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Tidskriftsartikel (refereegranskat)abstract
- The polyamines putrescine, spermidine and spermine play essential roles in cell proliferation and migration, two processes involved in the development of vascular disease. Thus, intervention with polyamine formation may represent a way to inhibit unwanted vascular smooth muscle cell (VSMC) proliferation. The aim of the present study was to assess the importance of polyamines for VSMC proliferation and vascular contractility. The rate-limiting step in polyamine biosynthesis is catalyzed by ornithine decarboxylase. Treatment with α-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, reduced DNA synthesis in primary rat VSMCs in a concentration-dependent manner with an IC50 value of 100 μM. Moreover, DFMO reduced VSMC migration assessed in a scratch assay. The DFMO-induced attenuation of VSMC proliferation was associated with lowered cellular amount of polyamines. The anti-proliferative effect of DFMO was specific since supplementation with polyamines reversed the effect of DFMO on proliferation and normalized cellular polyamine levels. Isometric force recordings in cultured rat tail artery rings showed that DFMO counteracts the decrease in contractility caused by culture with foetal bovine serum as growth stimulant. We conclude that inhibition of polyamine synthesis by DFMO may limit the first wave of cell proliferation and migration, which occurs in the acute phase after vascular injury. Besides its anti-proliferative effect, DFMO may prevent loss of the smooth muscle contractile phenotype in vascular injury. This article is protected by copyright. All rights reserved.
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| 5. |
- Svensson, Daniel, et al.
(författare)
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Inhibition of MicroRNA-125a Promotes Human Endothelial Cell Proliferation and Viability through an Antiapoptotic Mechanism.
- 2014
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Ingår i: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 51:3, s. 239-245
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Tidskriftsartikel (refereegranskat)abstract
- The microRNA-125a (miR-125a) is highly expressed in endothelial cells, but its role in vascular biology is not known. Endothelial cell proliferation and viability play an important role in endothelial healing, and we hypothesize that miR-125a regulates this process. The aim of the present study was to investigate if miR-125a controls human endothelial cell proliferation, viability and endothelial healing, and to assess the mechanisms involved. We showed that overexpression of miR-125a by transfection with miR-125a mimic reduced human umbilical vein endothelial cell (HUVEC) proliferation and viability, and stimulated apoptosis as demonstrated by a miR-125a-induced increase of the proportion of annexin V-positive cells monitored by flow cytometry. Moreover, we showed that the miR-125a mimic downregulated the antiapoptotic Bcl2 protein and upregulated caspase 3, suggesting that these two proteins represent molecular targets for miR-125a. Accordingly, transfection with miR-125a inhibitor, downregulating miR-125a expression, promoted HUVEC proliferation and viability, and reduced apoptosis. Importantly, transfection with miR-125a inhibitor promoted HUVEC tube formation in Matrigel, suggesting that reduction of miR-125a has a proangiogenic effect. In conclusion, downregulation of miR-125a through local transfection with miR-125a inhibitor might be a new way to enhance endothelial cell proliferation and viability, thereby promoting the reendothelialization observed in response to intimal injury. © 2014 S. Karger AG, Basel.
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| 6. |
- Turczynska, Karolina
(författare)
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Vascular smooth muscle mechanotransduction and plasticity-the role of microRNA, calcium signaling and actin polymerization
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Smooth muscle cells residing in the blood vessel media are constantly exposed to mechanical forces exerted by the intraluminal pressure. The smooth muscle senses and adapts to mechanical forces by activation of multiple signaling pathways and cytoskeletal rearrangements. Stretch of the vascular wall is therefore an important factor that controls smooth muscle cell phenotype and function. The goal of this thesis was to study the role of microRNAs and calcium-sensitive proline-rich tyrosine kinase (PYK 2) in stretch-induced signaling as well as to characterize genes whose expression is regulated by actin polymerization in smooth muscle. Murine portal vein cultured ex vivo under longitudinally applied load was used to study the effects of stretch. Spontaneous activity as well as stretch-induced synthesis of contractile/cytoskeletal proteins was diminished in portal vein lacking functional microRNAs (Dicer KO). In wild type portal vein, stretch down-regulated miR-144/451 cluster expression, which inversely correlated with increased activation of AMP-kinase and contractile differentiation of smooth muscle. Stretch increased phosphorylation of PYK 2 at Tyr402 in rat portal vein. The PYK 2 inhibitor, PF-4594755 reduced DNA and total protein synthesis, whereas stretch-induced mRNA expression of smooth muscle contractile markers was maintained. Stabilization of actin filaments in smooth muscle cells resulted in increased expression of a number of genes encoding proteins involved in cytoskeletal and contractile function, including dystrophin and synaptopodin 2. The expression of dystrophin and synaptopodin 2 was down-regulated in phenotypically modulated smooth muscle cells and after balloon-injury of human mammary artery. Furthermore, loss of dystrophin resulted in decreased smooth muscle contractile function. In summary, this study provides novel evidence for the role of microRNAs and calcium-sensitive PYK 2 in stretch-induced signaling in smooth muscle. Moreover, the data show that dystrophin and synaptopodin 2 are regulated by actin polymerization and that their expression is altered in models of vascular disease.
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