Showing papers on "Smoothelin published in 2018"

Contractile Smooth Muscle and Active Stress Generation in Porcine Common Carotids.

Abstract: The mechanical response of intact blood vessels to applied loads can be delineated into passive and active components using an isometric decomposition approach. Whereas the passive response is due predominantly to the extracellular matrix (ECM) proteins and amorphous ground substance, the active response depends on the presence of smooth muscle cells (SMCs) and the contractile machinery activated within those cells. To better understand determinants of active stress generation within the vascular wall, we subjected porcine common carotid arteries (CCAs) to biaxial inflation-extension testing under maximally contracted or passive SMC conditions and semiquantitatively measured two known markers of the contractile SMC phenotype: smoothelin and smooth muscle-myosin heavy chain (SM-MHC). Using isometric decomposition and established constitutive models, an intuitive but novel correlation between the magnitude of active stress generation and the relative abundance of smoothelin and SM-MHC emerged. Our results reiterate the importance of stretch-dependent active stress generation to the total mechanical response. Overall these findings can be used to decouple the mechanical contribution of SMCs from the ECM and is therefore a powerful tool in the analysis of disease states and potential therapies where both constituent are altered.

Vascular Cell Glycocalyx-Mediated Vascular Remodeling Induced by Hemodynamic Environmental Alteration.

Abstract: Vascular remodeling induced by hemodynamic stimuli contributes to the pathophysiology of cardiovascular diseases. The importance of vascular cells (endothelial cells and smooth muscle cells) glycocalyx in the mechanotransduction of flow-induced shear stress at the cellular and molecular levels has been demonstrated over the past decade. However, its potential mechanotransduction role in vascular remodeling has triggered little attention. In the present study, a home-made apparatus was used to expose the rat abdominal aorta to sterile, flow or no flow, normal-pressure or high-pressure conditions for 4 days. The histomophometric, cellular, and molecular analysis of vessels were performed. The results showed that after exposing the vessels in the flow and high-pressure condition, the apoptotic rate, the cell number, and the RNA level of contractile marker gene smooth muscle 22 of smooth muscle cells were significantly increased, whereas the expression of nitric oxide synthase, α-smooth muscle actin, smoothelin, and calponion showed no significant differences compared with the flow and normal-pressure groups. Moreover, the histomophometric analysis of vascular walls suggested a remodeling induced by flow and high-pressure loading consistent with the classic hypertensive aortic phenotype, which is characterized by a thicker and more rigid vascular wall as well as increased aortic diameter. However, those phenomena were totally abolished after compromising the integrity of glycocalyx by the treatment of vessels with hyaluronidase, which provided evidence of the important mechanotransduction role of the vascular cells glycocalyx in vascular remodeling induced by hemodynamic stimuli.

Smoothelins and the Control of Muscle Contractility.

Abstract: Smooth muscle cells display distinctive expression and organization of contractile filament proteins, which reflect a unique method of contractile regulation. As the focus of this review, the smoothelin and smoothelin-like family members represent a family of poorly understood muscle proteins that appear to act as structural components of the contractile apparatus. The protein family is characterized by the presence a single C-terminal type-2 calponin homology (CH) domain. Often used as the preferred marker of differentiated contractile smooth muscle cells, smoothelin A and B (SMTN-A and SMTN-B) may influence the contractile potential of smooth muscle cells. The more recently identified smoothelin-like proteins (SMTNL1 and SMTNL2) have more diverse functional implications. SMTNL1 is linked to the regulation of smooth muscle contractility and adaptations of both smooth and skeletal muscle to hypertension, pregnancy, and exercise training. The SMTNL1 protein is suggested to play multiple roles in muscle through functional interactions with contractile regulators (e.g., calmodulin, tropomyosin, and myosin phosphatase) as well as transcriptional control of the contractile phenotype and Ca2+-sensitizing capacity. These effects are associated with acute, reversible changes to the contractile state or long-term adaptations mediated by transcriptional changes in expression of contractile proteins. SMTNL2 remains essentially uncharacterized; however, its expression is high in skeletal muscle and could be associated with differentiating myocytes. Finally, emerging opportunities exist to understand the significance of smoothelins as disease-associated markers and in some cases as specific modulators of pathophysiology.

Characterization of voiding function and structural bladder changes in a rat model of neurogenic underactive bladder disease.

Abstract: Objectives To create an animal model for neurogenic underactive bladder disease (UAB) and identify markers to describe secondary myogenic changes in the bladder wall. Materials and methods Male rats underwent either bilateral pelvic nerve injury or sham surgery. Four weeks after surgery functional evaluation was performed and tissue was harvested. Functional evaluation consisted of analysis of voiding pattern, 24-h urine collection in a metabolic cage, in vivo cystometry and in-vitro contractile function assessment. PCR and immunohistochemical localization of different smooth muscle cell and extracellular matrix markers was performed on bladder strips. Results After pelvic nerve injury, dry bladder weight increased and voiding contractions were absent, resulting in overflow incontinence. In-vitro contractile response to carbachol was decreased. This was paired with an upregulation of synthetic smooth muscle cell (SMC) markers mRNA expression such as retinol binding protein 1 (RBP1), myosin 10 (MYH10) and osteopontin (OPN), and a downregulation of contractile SMC marker smoothelin (SMTL). The SMTL/OPN mRNA ratio was 50 times higher in sham bladders compared to PNI bladders. Conclusions The loss of in-vivo and in-vitro contractile function following pelvic nerve transection is characterized by a switch from a contractile to synthetic SMC phenotype, which is best characterized by the ratio SMTL/OPN mRNA expression. Modulating this phenotypical switch is a potential target for the development of UAB therapy. We suggest for the first time a set of markers that may be useful to evaluate therapeutic strategies on improvements in bladder wall structure.

Increased autophagy contributes to impaired smooth muscle function in neurogenic lower urinary tract dysfunction.

Abstract: AIMS To explore whether autophagy plays a role in the remodeling of bladder smooth muscle cells (SMCs) in children with neurogenic lower urinary tract dysfunction (NLUTD), we investigated the effect of autophagy in NLUTD in the paediatric population. METHODS Bladder biopsies were taken from children with NLUTD and healthy donors as controls. Samples were labeled with the SMC markers calponin, smoothelin, and the autophagy proteins LC3, ATG5, and Beclin1. The contractile ability of bladder derived SMCs was investigated. RESULTS ATG5 gene and protein was upregulated in NLUTD muscle tissue compared to normal bladder. NLUTD muscle exhibited a punctated immunostaining pattern for LC3 in a subset of the SMCs, confirming the accumulation of autophagosomes. Pronounced elevation of ATG5 in the SMC in NLUTD tissue was associated with a downregulation of the key contractile proteins smoothelin and calponin. Pharmacological blocking of autophagy completely stopped the cells growth in normal bladder SMCs. Inhibition of autophagy in the NLUTD SMCs, with already elevated levels of ATG5, resulted in a reduction of ATG5 protein expression to the basal level found in normal controls. CONCLUSIONS Our study suggests that autophagy is an important factor affecting the remodeling of SMCs and the alteration of functionality in bladder smooth muscle tissue in the NLUTD. Since autophagy can be influenced by oral medication, this finding might lead to novel strategies preventing the deterioration of NLUTD muscle.

[henotypic modulation of corporal cavernosum smooth muscle cells and erectile dysfunction: Advances in studies].

Abstract: Erectile dysfunction (ED) is closely related with the phenotypic modulation of corporal cavernosum smooth muscle cells (CCSMC), a transitional tendency of CCSMCs switching from the contractile phenotype to the synthetic or proliferative phenotype. The molecular markers of contractile CCSMCs include α-SMA, SMMHC, Calponin, Smoothelin, and Desmin, while those of synthetic or proliferative CCSMCs involve Vimentin, Osteopontin, and Collagen I. Current studies show that phenotypic transformation of CCSMCs is related to the pathophysiological processes of different types of ED, such as bilateral cavernous nerve injury-induced ED, diabetes mellitus-associated ED, arterial ED, hypertension-associated ED, and so on. In addition, such external factors as hypoxia, platelet-derived growth factor, and tobacco combustion gas may directly affect rats or CCSMCs and consequently lead to phenotypic conversion of CCSMCs. This article presents a systematic review of the studies on the correlation of phenotypic transition of CCSMCs with ED.

Ascending aortas from heart donors and CABG patients are not equivalent as control in aortopathy studies

Abstract: OBJECTIVES A careful selection of reference samples in studies on the pathogenesis of thoracic ascending aorta (TAA) dilation is crucial for reliability, consistency and reproducibility of experimental results. Several studies include control TAA samples from heart donors. Others include samples harvested during coronary artery bypass graft (CABG) procedures or a mix of samples from heart donors and CABG patients. We verified the equivalence/homogeneity of TAA samples from heart donors and CABG patients in terms of basal gene expression and thus their reliability as reference groups in aortopathy studies. DESIGN We analysed by RT-PCR and Western blot the differential expression of smoothelin, α-smooth muscle actin (α-SMA) and transforming growth factor-β1 (TGF-β1), selected as major players in smooth muscle cell and myofibroblast phenotype and remodelling. The mean age and comorbidities of subjects were consistent with data routinely seen in clinical practice. RESULTS Data revealed the loss of smoothelin in samples from CABG patients, together with a significant increase of α-SMA, while TGF-β1 dimer showed a marked increase in CABG patients versus heart donors, accompanied by a decrease of the corresponding mRNA. Differences in gene expression were maintained after adjustment for age. However, TGF-β1 mRNA and CABG patients' age showed a positive correlation (ρ = 0.89, p < .05), while α-SMA mRNA and age showed a negative correlation (ρ = -0.85, p < .05). CONCLUSIONS We revealed the non-equivalence of samples from heart donors and CABG patients, presumably for the presence of microscopic atherosclerotic lesions in CABG patients, suggesting the necessity of a careful selection of control groups in aortopathy studies.