1.
Turczynska, Karolina, et al.
(författare)
Regulation of vascular smooth muscle mechanotransduction by microRNAs and L-type calcium channels.
2013
Ingår i: Communicative & Integrative Biology. - : Informa UK Limited. - 1942-0889. ; 6:1, s. 22278-22278
Tidskriftsartikel (refereegranskat) abstract
The phenotype of smooth muscle cells is regulated by multiple environmental factors including mechanical forces. Mechanical stretch of mouse portal veins ex vivo has been shown to promote contractile differentiation by activation of the Rho-pathway, an effect that is dependent on the influx of calcium via L-type calcium channels. MicroRNAs have recently been demonstrated to play a significant role in the control of smooth muscle phenotype and in a recent report we investigated their role in vascular mechanosensing. By smooth muscle specific deletion of Dicer, we found that microRNAs are essential for smooth muscle differentiation in response to stretch by regulating CamKIIδ and L-type calcium channel expression. Furthermore, we suggest that loss of L-type calcium channels in Dicer KO is due to reduced expression of the smooth muscle-enriched microRNA, miR-145, which targets CamKIIδ. These results unveil a novel mechanism for miR-145 dependent regulation of smooth muscle phenotype.
2.
Alajbegovic, Azra, et al.
(författare)
Molecular regulation of arterial aneurysms : Role of actin dynamics and microRNAs in vascular smooth muscle
2017
Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 8:AUG, s. 569-569
Tidskriftsartikel (refereegranskat) abstract
Aortic aneurysms are defined as an irreversible increase in arterial diameter by morethan 50% relative to the normal vessel diameter. The incidence of aneurysm rupture isabout 10 in 100,000 persons per year and ruptured arterial aneurysms inevitably resultsin serious complications, which are fatal in about 40% of cases. There is also a hereditarycomponent of the disease and dilation of the ascending thoracic aorta is often associatedwith congenital heart disease such as bicuspid aortic valves (BAV). Furthermore, specificmutations that have been linked to aneurysm affect polymerization of actin filaments.Polymerization of actin is important to maintain a contractile phenotype of smooth musclecells enabling these cells to resist mechanical stress on the vascular wall caused by theblood pressure according to the law of Laplace. Interestingly, polymerization of actin alsopromotes smooth muscle specific gene expression via the transcriptional co-activatorMRTF, which is translocated to the nucleus when released from monomeric actin. Inaddition to genes encoding for proteins involved in the contractile machinery, recentstudies have revealed that several non-coding microRNAs (miRNAs) are regulated bythis mechanism. The importance of these miRNAs for aneurysm development is onlybeginning to be understood. This review will summarize our current understanding aboutthe influence of smooth muscle miRNAs and actin polymerization for the developmentof arterial aneurysms.
3.
Dahan, Diana, et al.
(författare)
Induction of angiotensin converting enzyme after miR-143/145 deletion is critical for impaired smooth muscle contractility.
2014
Ingår i: American Journal of Physiology: Cell Physiology. - : American Physiological Society. - 1522-1563 .- 0363-6143. ; 307:12, s. 1093-1101
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.
4.
Ekman, Mari, et al.
(författare)
HIF-mediated metabolic switching in bladder outlet obstruction mitigates the relaxing effect of mitochondrial inhibition.
2014
Ingår i: Laboratory Investigation. - : Elsevier BV. - 1530-0307 .- 0023-6837. ; 94:5, s. 557-568
Tidskriftsartikel (refereegranskat) abstract
Prior work demonstrated increased levels of hypoxia-inducible factor-1α (HIF-1α) in the bladder following outlet obstruction, associated with bladder growth and fibrosis. Here we hypothesized that HIF induction in outlet obstruction also switches energetic support of contraction from mitochondrial respiration to glycolysis. To address this hypothesis, we created infravesical outlet obstruction in female Sprague-Dawley rats and examined HIF induction and transcriptional activation. HIF-1α increased after 6 weeks of outlet obstruction as assessed by western blotting and yet transcription factor-binding site analysis indicated HIF activation already at 10 days of obstruction. Accumulation HIF-2α and of Arnt2 proteins were found at 10 days, providing an explanation for the lack of correlation between HIF-1α protein and transcriptional activation. HIF signature targets, including Slc2a1, Tpi1, Eno1 and Ldha increased in obstructed compared with sham-operated bladders. The autophagy markers Bnip3 and LC3B-II were also increased at 6 week of obstruction, but electron microscopy did not support mitophagy. Mitochondria were, however, remodeled with increased expression of Cox4 compared with other markers. In keeping with a switch toward glycolytic support of contraction, we found that relaxation by the mitochondrial inhibitor cyanide was reduced in obstructed bladders. This was mimicked by organ culture with the HIF-inducer dimethyloxalylglycine, which also upregulated expression of Ldha. On the basis of these findings, we conclude that HIF activation in outlet obstruction involves mechanisms beyond the accumulation of HIF-1α protein and that it results in a switch of the energetic support of contraction to anaerobic glycolysis. This metabolic adaptation encompasses increased expression of glucose transporters and glycolytic enzymes combined with mitochondrial remodeling. Together, these changes uphold contractility when mitochondrial respiration is limited.Laboratory Investigation advance online publication, 3 March 2014; doi:10.1038/labinvest.2014.48.
5.
Sadegh, Mardjaneh Karbalaei, et al.
(författare)
Deletion of dicer in smooth muscle affects voiding pattern and reduces detrusor contractility and neuroeffector transmission.
2012
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:4
Tidskriftsartikel (refereegranskat) abstract
MicroRNAs have emerged as important regulators of smooth muscle phenotype and may play important roles in pathogenesis of various smooth muscle related disease states. The aim of this study was to investigate the role of miRNAs for urinary bladder function. We used an inducible and smooth muscle specific Dicer knockout (KO) mouse which resulted in significantly reduced levels of miRNAs, including miR-145, miR-143, miR-22, miR125b-5p and miR-27a, from detrusor preparations without mucosa. Deletion of Dicer resulted in a disturbed micturition pattern in vivo and reduced depolarization-induced pressure development in the isolated detrusor. Furthermore, electrical field stimulation revealed a decreased cholinergic but maintained purinergic component of neurogenic activation in Dicer KO bladder strips. The ultrastructure of detrusor smooth muscle cells was well maintained, and the density of nerve terminals was similar. Western blotting demonstrated reduced contents of calponin and desmin. Smooth muscle α-actin, SM22α and myocardin were unchanged. Activation of strips with exogenous agonists showed that depolarization-induced contraction was preferentially reduced; ATP- and calyculin A-induced contractions were unchanged. Quantitative real time PCR and western blotting demonstrated reduced expression of Cav1.2 (Cacna1c). It is concluded that smooth muscle miRNAs play an important role for detrusor contractility and voiding pattern of unrestrained mice. This is mediated in part via effects on expression of smooth muscle differentiation markers and L-type Ca(2+) channels in the detrusor.
6.
Swärd, Karl, et al.
(författare)
Arterial dysfunction but maintained systemic blood pressure in cavin-1-deficient mice.
2014
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3
Tidskriftsartikel (refereegranskat) abstract
Caveolae are omega-shaped plasma membrane micro-domains that are abundant in cells of the vascular system. Formation of caveolae depends on caveolin-1 and cavin-1 and lack of either protein leads to loss of caveolae. Mice with caveolin-1 deficiency have dysfunctional blood vessels, but whether absence of cavin-1 similarly leads to vascular dysfunction is not known. Here we addressed this hypothesis using small mesenteric arteries from cavin-1-deficient mice. Cavin-1-reporter staining was intense in mesenteric arteries, brain arterioles and elsewhere in the vascular system, with positive staining of both endothelial and smooth muscle cells. Arterial expression of cavin-1, -2 and -3 was reduced in knockout (KO) arteries as was expression of caveolin-1, -2 and -3. Caveolae were absent in the endothelial and smooth muscle layers of small mesenteric arteries as determined by electron microscopy. Arginase, a negative regulator of nitric oxide production, was elevated in cavin-1 deficient arteries as was contraction in response to the α1-adrenergic agonist cirazoline. Detailed assessment of vascular dimensions revealed increased media thickness and reduced distensibility, arguing that enhanced contraction was due to increased muscle mass. Contrasting with increased α1-adrenergic contraction, myogenic tone was essentially absent and this appeared to be due in part to increased nitric oxide production. Vasomotion was less frequent in the knock-out vessels. In keeping with the opposing influences on arterial resistance of increased agonist-induced contractility and reduced myogenic tone, arterial blood pressure was unchanged in vivo. We conclude that deficiency of cavin-1 affects the function of small arteries, but that opposing influences on arterial resistance balance each other such that systemic blood pressure in unstressed mice is well maintained.
7.
Turczynska, Karolina, et al.
(författare)
Stretch-Sensitive Down-Regulation of the miR-144/451 Cluster in Vascular Smooth Muscle and Its Role in AMP-Activated Protein Kinase Signaling.
2013
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5
Tidskriftsartikel (refereegranskat) 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.
8.
Zeidan, Asad, et al.
(författare)
Stretch-induced contractile differentiation of vascular smooth muscle: sensitivity to actin polymerization inhibitors.
2003
Ingår i: American Journal of Physiology: Cell Physiology. - : American Physiological Society. - 1522-1563 .- 0363-6143. ; 284:6, s. 1387-1396
Tidskriftsartikel (refereegranskat) abstract
Signaling mechanisms for stretch-dependent growth and differentiation of vascular smooth muscle were investigated in mechanically loaded rat portal veins in organ culture. Stretch-dependent protein synthesis was found to depend on endogenous release of angiotensin II. Autoradiography after [35S]methionine incorporation revealed stretch-dependent synthesis of several proteins, of which SM22 and actin were particularly prominent. Inhibition of RhoA activity by cell-permeant C3 toxin increased tissue mechanical compliance and reduced stretch-dependent extracellular signal-regulated kinase (ERK)1/2 activation, growth, and synthesis of actin and SM22, suggesting a role of the actin cytoskeleton. In contrast, inhibition of Rho-associated kinase by Y-27632 did not reduce ERK1/2 phosphorylation or actin and SM22 synthesis and did not affect tissue mechanical compliance but still inhibited overall growth. The actin polymerization inhibitors latrunculin B and cytochalasin D both inhibited growth and caused increased tissue compliance. Whereas latrunculin B concentration-dependently reduced actin and SM22 synthesis, cytochalasin D did so at low (10-8 M) but not at high (10-6 M) concentration. The results show that stretch stabilizes the contractile smooth muscle phenotype. Stretch-dependent differentiation marker expression requires an intact cytoskeleton for stretch sensing, control of protein expression via the level of unpolymerized G-actin, or both.
9.
Albinsson, Sebastian, et al.
(författare)
Arterial remodeling and plasma volume expansion in caveolin-1 deficient mice.
2007
Ingår i: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 293, s. 1222-1231
Tidskriftsartikel (refereegranskat) abstract
Caveolin- 1 ( Cav- 1) is essential for the morphology of membrane caveolae and exerts a negative influence on a number of signaling systems, including nitric oxide ( NO) production and activity of the MAP kinase cascade. In the vascular system, ablation of caveolin- 1 may thus be expected to cause arterial dilatation and increased vessel wall mass ( remodeling). This was tested in Cav- 1 knockout ( KO) mice by a detailed morphometric and functional analysis of mesenteric resistance arteries, shown to lack caveolae. Quantitative morphometry revealed increased media thickness and media- to- lumen ratio in KO. Pressure- induced myogenic tone and flow- induced dilatation were decreased in KO arteries, but both were increased toward wild- type ( WT) levels following NO synthase ( NOS) inhibition. Isometric force recordings following NOS inhibition showed rightward shifts of passive and active length- force relationships in KO, and the force response to alpha 1- adrenergic stimulation was increased. In contrast, media thickness and force response of the aorta were unaltered in KO vs. WT, whereas lumen diameter was increased. Mean arterial blood pressure during isoflurane anesthesia was not different in KO vs. WT, but greater fluctuation in blood pressure over time was noted. Following NOS inhibition, fluctuations disappeared and pressure increased twice as much in KO ( 38 +/- 6%) compared with WT ( 17 +/- 3%). Tracer- dilution experiments showed increased plasma volume in KO. We conclude that NO affects blood pressure more in Cav- 1 KO than in WT mice and that restructuring of resistance vessels and an increased responsiveness to adrenergic stimulation compensate for a decreased tone in Cav- 1 KO mice.
10.
Albinsson, Sebastian, et al.
(författare)
Can microRNAs control vascular smooth muscle phenotypic modulation and the response to injury?
2010
Ingår i: Physiological Genomics. - : American Physiological Society. - 1094-8341 .- 1531-2267. ; okt
Tidskriftsartikel (refereegranskat) abstract
Vascular smooth muscle cell (VSMC) migration and proliferation are critical events in vascular proliferative diseases. Recent studies have established micro-RNAs (miRNAs) as important mediators for the modulation of VSMC phenotype by targeting transcription factors and the cytoskeleton, which act as molecular switches for VSMC differentiation. The importance of miRNAs for VSMC development, differentiation and function is evident by the fact that loss of the miRNA processing enzyme Dicer in VSMCs results in embryonic lethality due to severe vascular abnormalities. In addition, a role of specific miRNAs for neointimal hyperplasia following vascular injury has been reported which provides interesting possibilities for future therapeutical targets against vascular disease. Herein, we summarize recent advances regarding the role of miRNAs in VSMC phenotype modulation and response to injury.
