| 1. |
- Albinsson, Sebastian, et al.
(author)
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Stretch-dependent smooth muscledifferentiation in theportal vein - role of actin polymerization, calcium signaling and microRNAs.
- 2014
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In: Microcirculation. - : Wiley. - 1549-8719 .- 1073-9688. ; 21:3, s. 230-238
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Research review (peer-reviewed)abstract
- The mechanical forces acting onsmooth muscle cells in the vascular wall are known to regulate processes such as vascular remodeling and contractile differentiation. However, investigations to elucidate the underlying mechanisms of mechanotransduction in smooth muscle have been hampered by technical limitations associated with mechanical studies on pressurized small arteries, due primarily to the small amount of available tissue. The murine portal vein is a relatively large vessel showing myogenic tone that in many respects recapitulates the properties of small resistance vessels. Studies on stretched portal veins to elucidate mechanisms of mechanotransduction in the vascular wall have shown that stretch-sensitive regulation of contractile differentiation is mediated via Rho-activation and actin polymerization, while stretch-induced growth is regulated by the MAP-kinase pathway. In this review, we have summarized findings on mechanotransduction in the portal vein with focus on stretch-induced contractile differentiation and the role of calcium, actin polymerization and microRNAs in this response. This article is protected by copyright. All rights reserved.
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| 2. |
- Bhattachariya, Anirban, et al.
(author)
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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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In: Cardiovascular Research. - : Oxford University Press (OUP). - 1755-3245 .- 0008-6363. ; 101:2, s. 288-296
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Journal article (peer-reviewed)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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| 3. |
- Bhattachariya, Anirban, et al.
(author)
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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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In: Physiological Reports. - : Wiley. - 2051-817X. ; 2:7
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Journal article (peer-reviewed)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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| 4. |
- Bhattachariya, Anirban
(author)
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Regulation of the myogenic response and stretch-induced calcium signaling in the vascular wall: Novel insights into the role of microRNAs and protein tyrosine kinase 2
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Intraluminal pressure has a significant impact on vascular adaptability, phenotype and regulation of blood flow and pressure. On one hand, increased pressure/stretch for a prolonged time can cause structural changes in vessel wall; on the other hand, lack of pressure/stretch can promote a phenotype shift. This thesis investigates novel roles of microRNAs and protein tyrosine kinase 2 in pressure/stretch-induced signaling mechanisms in the vascular wall. Using two different knockout mouse models, we uncovered a novel role of microRNAs in the pressure-induced myogenic response. We demonstrated that global deletion of smooth muscle-specific microRNAs causes a loss of pressure-induced contraction and that this likely involves diminished calcium influx due to reduced stretch-induced activation of the PI3K/Akt pathway. Similarly, global deletion of the smooth muscle enriched miRNA-143/145 also depleted myogenic responses but this effect could be due to several combined factors including loss of calcium influx and decreased expression of myosin light chain kinase. Furthermore portal veins of miRNA-143/145 KO mice exhibit lack of stretch-induced contractile differentiation, which may in part be due to a reduced expression of L-type calcium channels caused by an increased expression of the transcriptional repressor DREAM. Using a novel small molecule inhibitor of PYK2, we demonstrated that PYK2 could distinguish between non-voltage and voltage-dependent calcium pools to initiate signal transduction in the smooth muscle of portal vein. Inhibition of PYK2 can reduce phenotype modulation and apoptosis in balloon injured carotid arteries. In conclusion, we have established an indispensable role of microRNAs in the presssure-induced myogenic response and maintainance of stretch-induced conctractile differentiation. Morover we have established that PYK2 is involved in stretch-induced calcium handling in spontaneously active portal vein and in phenotypic shift of smooth muscle cells following vascular injury.
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| 5. |
- Bhattachariya, Anirban, et al.
(author)
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Spontaneous activity and stretch-induced contractile differentiation are reduced in vascular smooth muscle of miR-143/145 knockout mice.
- 2015
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In: Acta Physiologica. - : Wiley. - 1748-1716 .- 1748-1708. ; 215:3, s. 133-143
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Journal article (peer-reviewed)abstract
- Stretch is essential for maintaining the contractile phenotype of vascular smooth muscle cells, and small non-coding microRNAs are known to be important in this process. Using a Dicer knockout model, we have previously reported that microRNAs are essential for stretch-induced differentiation and regulation of L-type calcium channel expression. The aim of this study was to investigate the importance of the smooth muscle-enriched miR-143/145 microRNA cluster for stretch-induced differentiation of the portal vein.
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| 6. |
- Di Russo, Jacopo, et al.
(author)
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Endothelial basement membrane laminin 511 is essential for shear stress response
- 2017
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In: EMBO Journal. - : EMBO. - 0261-4189 .- 1460-2075. ; 36:2, s. 183-201
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Journal article (peer-reviewed)abstract
- Shear detection and mechanotransduction by arterial endothelium requires junctional complexes containing PECAM-1 and VE-cadherin, as well as firm anchorage to the underlying basement membrane. While considerable information is available for junctional complexes in these processes, gained largely from in vitro studies, little is known about the contribution of the endothelial basement membrane. Using resistance artery explants, we show that the integral endothelial basement membrane component, laminin 511 (laminin α5), is central to shear detection and mechanotransduction and its elimination at this site results in ablation of dilation in response to increased shear stress. Loss of endothelial laminin 511 correlates with reduced cortical stiffness of arterial endothelium in vivo, smaller integrin β1-positive/vinculin-positive focal adhesions, and reduced junctional association of actin–myosin II. In vitro assays reveal that β1 integrin-mediated interaction with laminin 511 results in high strengths of adhesion, which promotes p120 catenin association with VE-cadherin, stabilizing it at cell junctions and increasing cell–cell adhesion strength. This highlights the importance of endothelial laminin 511 in shear response in the physiologically relevant context of resistance arteries.
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| 7. |
- Ekman, Mari, et al.
(author)
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Mir-29 repression in bladder outlet obstruction contributes to matrix remodeling and altered stiffness.
- 2013
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:12
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Journal article (peer-reviewed)abstract
- Recent work has uncovered a role of the microRNA (miRNA) miR-29 in remodeling of the extracellular matrix. Partial bladder outlet obstruction is a prevalent condition in older men with prostate enlargement that leads to matrix synthesis in the lower urinary tract and increases bladder stiffness. Here we tested the hypothesis that miR-29 is repressed in the bladder in outlet obstruction and that this has an impact on protein synthesis and matrix remodeling leading to increased bladder stiffness. c-Myc, NF-κB and SMAD3, all of which repress miR-29, were activated in the rat detrusor following partial bladder outlet obstruction but at different times. c-Myc and NF-κB activation occurred early after obstruction, and SMAD3 phosphorylation increased later, with a significant elevation at 6 weeks. c-Myc, NF-κB and SMAD3 activation, respectively, correlated with repression of miR-29b and miR-29c at 10 days of obstruction and with repression of miR-29c at 6 weeks. An mRNA microarray analysis showed that the reduction of miR-29 following outlet obstruction was associated with increased levels of miR-29 target mRNAs, including mRNAs for tropoelastin, the matricellular protein Sparc and collagen IV. Outlet obstruction increased protein levels of eight out of eight examined miR-29 targets, including tropoelastin and Sparc. Transfection of human bladder smooth muscle cells with antimiR-29c and miR-29c mimic caused reciprocal changes in target protein levels in vitro. Tamoxifen inducible and smooth muscle-specific deletion of Dicer in mice reduced miR-29 expression and increased tropoelastin and the thickness of the basal lamina surrounding smooth muscle cells in the bladder. It also increased detrusor stiffness independent of outlet obstruction. Taken together, our study supports a model where the combined repressive influences of c-Myc, NF-κB and SMAD3 reduce miR-29 in bladder outlet obstruction, and where the resulting drop in miR-29 contributes to matrix remodeling and altered passive mechanical properties of the detrusor.
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| 8. |
- Grossi, Mario, et al.
(author)
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Pyk2 inhibition promotes contractile differentiation in arterial smooth muscle
- 2017
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In: Journal of Cellular Physiology. - : Wiley. - 0021-9541. ; 232:11, s. 3088-3102
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Journal article (peer-reviewed)abstract
- Modulation from contractile to synthetic phenotype of vascular smooth muscle cells is a central process in disorders involving compromised integrity of the vascular wall. Phenotype modulation has been shown to include transition from voltage-dependent toward voltage-independent regulation of the intracellular calcium level, and inhibition of non-voltage dependent calcium influx contributes to maintenance of the contractile phenotype. One possible mediator of calcium-dependent signaling is the FAK-family non-receptor protein kinase Pyk2, which is activated by a number of stimuli in a calcium-dependent manner. We used the Pyk2 inhibitor PF-4594755 and Pyk2 siRNA to investigate the role of Pyk2 in phenotype modulation in rat carotid artery smooth muscle cells and in cultured intact arteries. Pyk2 inhibition promoted the expression of smooth muscle markers at the mRNA and protein levels under stimulation by FBS or PDGF-BB and counteracted phenotype shift in cultured intact carotid arteries and balloon injury ex vivo. During long-term (24–96 hr) treatment with PF-4594755, smooth muscle markers increased before cell proliferation was inhibited, correlating with decreased KLF4 expression and differing from effects of MEK inhibition. The Pyk2 inhibitor reduced Orai1 and preserved SERCA2a expression in carotid artery segments in organ culture, and eliminated the inhibitory effect of PDGF stimulation on L-type calcium channel and large-conductance calcium-activated potassium channel expression in carotid cells. Basal intracellular calcium level, calcium wave activity, and store-operated calcium influx were reduced after Pyk2 inhibition of growth-stimulated cells. Pyk2 inhibition may provide an interesting approach for preserving vascular smooth muscle differentiation under pathophysiological conditions.
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| 9. |
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| 10. |
- Turczynska, Karolina, et al.
(author)
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Stretch-Sensitive Down-Regulation of the miR-144/451 Cluster in Vascular Smooth Muscle and Its Role in AMP-Activated Protein Kinase Signaling.
- 2013
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5
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Journal article (peer-reviewed)abstract
- Vascular smooth muscle cells are constantly exposed to mechanical force by the blood pressure, which is thought to regulate smooth muscle growth, differentiation and contractile function. We have previously shown that the expression of microRNAs (miRNAs), small non-coding RNAs, is essential for regulation of smooth muscle phenotype including stretch-dependent contractile differentiation. In this study, we have investigated the effect of mechanical stretch on miRNA expression and the role of stretch-sensitive miRNAs for intracellular signaling in smooth muscle. MiRNA array analysis, comparing miRNA levels in stretched versus non-stretched portal veins, revealed a dramatic decrease in the miR-144/451 cluster level. Because this miRNA cluster is predicted to target AMPK pathway components, we next examined activation of this pathway. Diminished miR-144/451 expression was inversely correlated with increased phosphorylation of AMPKα at Thr172 in stretched portal vein. Similar to the effect of stretch, contractile differentiation could be induced in non-stretched portal veins by the AMPK activator, AICAR. Transfection with miR-144/451 mimics reduced the protein expression level of mediators in the AMPK pathway including MO25α, AMPK and ACC. This effect also decreased AICAR-induced activation of the AMPK signaling pathway. In conclusion, our results suggest that stretch-induced activation of AMPK in vascular smooth muscle is in part regulated by reduced levels of miR-144/451 and that this effect may play a role in promoting contractile differentiation of smooth muscle cells.
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