scholarly journals Capillary pericytes express α-smooth muscle actin, which requires prevention of filamentous-actin depolymerization for detection

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Luis Alarcon-Martinez ◽  
Sinem Yilmaz-Ozcan ◽  
Muge Yemisci ◽  
Jesse Schallek ◽  
Kıvılcım Kılıç ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Muscle Actin ◽  
Filamentous Actin ◽  
Stabilizing Agents ◽  
Actin Depolymerization ◽  
Order Branch ◽  
Freeze Fixation ◽  
Interfering Rna ◽  
Retinal Capillaries

Recent evidence suggests that capillary pericytes are contractile and play a crucial role in the regulation of microcirculation. However, failure to detect components of the contractile apparatus in capillary pericytes, most notably α-smooth muscle actin (α-SMA), has questioned these findings. Using strategies that allow rapid filamentous-actin (F-actin) fixation (i.e. snap freeze fixation with methanol at −20°C) or prevent F-actin depolymerization (i.e. with F-actin stabilizing agents), we demonstrate that pericytes on mouse retinal capillaries, including those in intermediate and deeper plexus, express α-SMA. Junctional pericytes were more frequently α-SMA-positive relative to pericytes on linear capillary segments. Intravitreal administration of short interfering RNA (α-SMA-siRNA) suppressed α-SMA expression preferentially in high order branch capillary pericytes, confirming the existence of a smaller pool of α-SMA in distal capillary pericytes that is quickly lost by depolymerization. We conclude that capillary pericytes do express α-SMA, which rapidly depolymerizes during tissue fixation thus evading detection by immunolabeling.

scholarly journals Author response: Capillary pericytes express α-smooth muscle actin, which requires prevention of filamentous-actin depolymerization for detection

2018 ◽  
Author(s):  
Luis Alarcon-Martinez ◽  
Sinem Yilmaz-Ozcan ◽  
Muge Yemisci ◽  
Jesse Schallek ◽  
Kıvılcım Kılıç ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Author Response ◽  
Muscle Actin ◽  
Filamentous Actin ◽  
Actin Depolymerization

scholarly journals Alpha-Smooth Muscle Actin-Positive Perivascular Cells in Diabetic Retina and Choroid

2020 ◽  
Vol 21 (6) ◽  
pp. 2158 ◽  
Author(s):  
Soo Jin Kim ◽  
Sang A. Kim ◽  
Yeong A. Choi ◽  
Do Young Park ◽  
Junyeop Lee
Keyword(s):  
Diabetic Retinopathy ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Smooth Muscle Actin ◽  
Muscle Cells ◽  
Higher Order ◽  
Muscle Actin ◽  
Diabetic Mice ◽  
Mural Cells ◽  
Retinal Capillaries

Structural alterations of pericytes in microvessels are important features of diabetic retinopathy. Although capillary pericytes had been known not to have α-smooth muscle actin (αSMA), a recent study revealed that a specific fixation method enabled the visualization of αSMA along retinal capillaries. In this study, we applied snap-fixation in wild type and streptozotocin-induced diabetic mice to evaluate the differences in vascular smooth muscle cells of the retina and the choroid. Mice eyeballs were fixed in ice-cold methanol to prevent the depolymerization of filamentous actin. Snap-fixated retina showed αSMA expression in higher-order branches along the capillaries as well as the arterioles and venules, which were not detected by paraformaldehyde fixation. In contrast, most choriocapillaris, except those close to the arterioles, were not covered with αSMA-positive perivascular mural cells. Large choroidal vessels were covered with more αSMA-positive cells in the snap-fixated eyes. Diabetes induced less coverage of αSMA-positive perivascular mural cells overall, but they reached higher-order branches of the retinal capillaries, which was prominent in the aged mice. More αSMA-positive pericytes were observed in the choroid of diabetic mice, but the αSMA-positive expression reduced with aging. This study suggests the potential role of smooth muscle cells in the pathogenesis of age-related diabetic retinopathy and choroidopathy.

scholarly journals Cytotoxic Influence of Khat (Catha edulis (Vahl) Forssk. ex Endl) on Oral Fibroblasts, Squamous Carcinoma Cells, and Expression of α Smooth Muscle Actin

2021 ◽  
Vol 11 (8) ◽  
pp. 3524
Author(s):  
Azeem Ul Yaqin Syed ◽  
Muhammad A. Ahmed ◽  
Eman I. AlSagob ◽  
Mansour Al-Askar ◽  
Abdulrahman M. AlMubarak ◽  
...  
Keyword(s):  
Cell Death ◽  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Control Cell ◽  
Squamous Carcinoma ◽  
Carcinoma Cells ◽  
Muscle Actin ◽  
Catha Edulis ◽  
Squamous Carcinoma Cells ◽  
Dose Dependent

The aim was to determine the cytotoxicity of Khat (Catha edulis (Vahl) Forssk. ex Endl) on normal oral fibroblasts (NOFs) and SCC4 (squamous carcinoma cells) along with expression of α-smooth muscle actin (α-SMA) in fibroblasts. Khat filtrate was prepared to obtain a concentrated viscous solution. NOFs and SCC4 cells were cultured in biological cabinets and were grown in Dulbeccos’ modified Eagles medium. Frozen cells were thawed at 37 °C and cell seeding was performed. NOFs and SCC4 cells were seeded on 96 well plates and allowed to attach. The medium was removed and a fresh medium containing different concentrations of Khat was added. The group without Khat served as a negative control and 4% paraformaldehyde as the positive control. Cell viability was assessed using the MTT assay and effect of Khat on fibroblast and SCC4 phenotypes was evaluated by immunostaining. Analysis of variance was used to assess data (p < 0.05). NOF 316 showed cell death in response to 4% paraformaldehyde, 12.5, 6.25, and 3.12 mg/mL of Khat. The highest concentration of Khat (25 mg/mL) failed to cause cytotoxicity of NOF 316. NOF 319 and NOF 26 displayed cell death at all concentrations of Khat, however, cytotoxicity was not dose dependent. NOF 18 and SCC4 cells showed dose-dependent cell death. NOF 316 showed α-SMA expression after 1 mg/mL of Khat exposure. Not all fibroblasts were α-SMA-positive, suggesting specific activation of a subset of fibroblasts. Khat is cytotoxic to NOF and SCC4 cells. Furthermore, it can also cause activation and phenotypic changes in oral fibroblasts, indicating a potential role in progression of oral squamous cell carcinoma.

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