Distribution of cytoskeletal components in endothelial cells in the Guinea pig renal artery

Effects of Mechanical Stress on Endothelial Cells In Situ and In Vitro

Endothelial cells lining blood vessels are essential for maintaining vascular homeostasis and mediate several pathological and physiological processes. Mechanical stresses generated by blood flow and other biomechanical factors significantly affect endothelial cell activity. Here, we review how mechanical stresses, both in situ and in vitro, affect endothelial cells. We review the basic principles underlying the cellular response to mechanical stresses. We also consider the implications of these findings for understanding the mechanisms of mechanotransducer and mechano-signal transduction systems by cytoskeletal components.

Effects of Electrical Stimulation on the Signal Transduction-Related Proteins, c-Src and Focal Adhesion Kinase, in Fibroblasts

Electrical stimulation of the skin and muscles, e.g., in the fields of rehabilitation medicine and acupuncture, is known to locally increase blood flow and metabolism, and thus have beneficial health effects. However, little is known about the changes in cellular morphology or regulation of the localization of specific proteins in response to electrical stimuli. The present study was performed to examine the effects of electrical stimulation on the cytoskeletal system of cultured fibroblasts. Following application of electrical stimulation to cultured fibroblastic cells for a period of about 2 h, the stress fibers in the cells became thicker and the cells showed a contracted appearance. Cells were subjected to periodic electrical stimulation for 0 (unstimulated control), 2, 5, or 20 h. The stress fibers showed an increase in thickness within 2 h, and became gradually thicker until 20 h. In addition, the focal adhesions and stress fibers were enlarged after 2 h of continuous stimulation, and both stress fibers and focal adhesions became larger and thicker after 20 h of periodic stimulation. Cells showed increased staining of focal adhesions with anti-phosphotyrosine antibody (PY-20) after electrical stimulation. Cells also showed increased staining of tyrosine-phosphorylated focal adhesion kinase (FAK) (pY397) and tyrosine-phosphorylated c-Src (pY418), indicating that electrical stimulation affected signal transduction-related proteins.

FAK-Dependent Cell Motility and Cell Elongation

Fibroblastic cells show specific substrate selectivity for typical cell–substrate adhesion. However, focal adhesion kinase (FAK) contributes to controlling the regulation of orientation and polarity. When fibroblasts attach to micropatterns, tyrosine-phosphorylated proteins and FAK are both detected along the inner border between the adhesive micropatterns and the nonadhesive glass surface. FAK likely plays important roles in regulation of cell adhesion to the substrate, as FAK is a tyrosine-phosphorylated protein that acts as a signal transduction molecule at sites of cell–substrate attachment, called focal adhesions. FAK has been suggested to play a role in the attachment of cells at adhesive micropatterns by affecting cell polarity. Therefore, the localization of FAK might play a key role in recognition of the border of the cell with the adhesive micropattern, thus regulating cell polarity and the cell axis. This review discusses the regulation and molecular mechanism of cell proliferation and cell elongation by FAK and its associated signal transduction proteins.

Arrangement of Renal Arteries in Guinea Pig

The aim of this study was to describe origin, localization, and variations of renal arteries in guinea pig. The study was carried out on 26 adult guinea pigs. We prepared corrosion casts of the guinea pig arterial system. Batson's corrosion casting kit no. 17 was used as the casting medium. In 57.7% of specimens, a. renalis dextra was present as a single vessel with different level of its origin from aorta abdominalis. In 38.5% of specimens, two aa. renales dextrae were present with variable origin and arrangement. The presence of three aa. renales dextrae we found in one specimen. In 76.9% of specimens, a. renalis sinistra was present as a single vessel with different level of its origin from aorta abdominalis and variable arrangement. In 23.1% of specimens, we found two aa. renales sinistrae with variable origin and arrangement. The anatomical knowledge of the renal arteries, and its variations are of extreme importance for the surgeon that approaches the retroperitoneal region in several experiments, results of which are extrapolated in human. This is the first work dealing with the description of renal arteries arrangement in guinea pig. Anat Rec, 300:556-559, 2017. © 2016 Wiley Periodicals, Inc.

Microwave-Assisted Tissue Preparation for Rapid Fixation, Decalcification, Antigen Retrieval, Cryosectioning, and Immunostaining

Microwave irradiation of tissue during fixation and subsequent histochemical staining procedures significantly reduces the time required for incubation in fixation and staining solutions. Minimizing the incubation time in fixative reduces disruption of tissue morphology, and reducing the incubation time in staining solution or antibody solution decreases nonspecific labeling. Reduction of incubation time in staining solution also decreases the level of background noise. Microwave-assisted tissue preparation is applicable for tissue fixation, decalcification of bone tissues, treatment of adipose tissues, antigen retrieval, and other special staining of tissues. Microwave-assisted tissue fixation and staining are useful tools for histological analyses. This review describes the protocols using microwave irradiation for several essential procedures in histochemical studies, and these techniques are applicable to other protocols for tissue fixation and immunostaining in the field of cell biology.

High Pulsatility Flow Induces Acute Endothelial Inflammation through Overpolarizing Cells to Activate NF-κB

Large artery stiffening and small artery inflammation are both well-known pathological features of pulmonary and systemic hypertension, but the relationship between them has been seldom explored. We previously demonstrated that stiffening-induced high pulsatility flow stimulated a pro-inflammatory response in distal pulmonary artery endothelial cells (PAEC). Herein, we hypothesized that high pulsatility flow activated PAEC pro-inflammatory responses are mediated through cell structural remodeling and cytoskeletal regulation of NF-κB translocation. To test this hypothesis, cells were exposed to low and high pulsatility flows with the same mean physiological flow shear stress. Results showed that unidirectional, high pulsatility flow led to continuous, high-level NF-κB activation, whereas low pulsatility flow induced only transient, minor NF-κB activation. Compared to cell shape under the static condition, low pulsatility flow induced cell elongation with a polarity index of 1.7, while high pulsatility flow further increased the cell polarity index to a value greater than 3. To explore the roles of cytoskeletal proteins in transducing high flow pulsatility into NF-κB activation, PAECs were treated with drugs that reduce the synthesis-breakdown dynamics of F-actin or microtubules (cytochalasin D, phalloidin, nocodazole, and taxol) prior to flow. Results showed that these pre-treatments suppressed NF-κB activation induced by high pulsatility flow, but drugs changing dynamics of F-actin enhanced NF-κB activation even under low pulsatility flow. Taxol was further circulated in the flow to examine its effect on cells. Results showed that circulating taxol (10nM) reduced PAEC polarity, NF-κB activation, gene expression of pro-inflammatory molecules (ICAM-1 and VCAM-1), and monocyte adhesion on the PAECs under high pulsatility flow. Therefore, taxol effectively reduced high pulsatility flow-induced PAEC overpolarization and pro-inflammatory responses via inhibiting cytoskeletal remodeling. This study suggests that stabilizing microtubule dynamics might bea potential therapeutic means of reducing endothelial inflammation caused by high pulsatility flow.