ROCK1 translocates from non-caveolar to caveolar regions upon KCl stimulation in airway smooth muscle

Estrogen receptors differentially regulate intracellular calcium handling in human nonasthmatic and asthmatic airway smooth muscle cells

Asthma is defined as chronic inflammation of the airways and is characterized by airway remodeling, hyperresponsiveness, and acute bronchoconstriction of airway smooth muscle (ASM) cells. Clinical findings suggest a higher incidence and severity of asthma in adult women, indicating a concrete role of sex steroids in modulating the airway tone. Estrogen, a major female sex steroid mediates its role through estrogen receptors (ER) ERα and ERβ, which are shown to be expressed in human ASM, and their expression is upregulated in lung inflammation and asthma. Previous studies suggested rapid, nongenomic signaling of estrogen via ERs reduces intracellular calcium ([Ca²⁺]_i), thereby promoting relaxation of ASM. However, long-term ER activation on [Ca²⁺]_i regulation in human ASM during inflammation or in asthma is still not known. In Fura-2-loaded nonasthmatic and asthmatic human ASM cells, we found that prolonged (24 h) exposure to ERα agonist (PPT) increased [Ca²⁺]_i response to histamine, whereas ERβ activation (WAY) led to decreased [Ca²⁺] compared with vehicle. This was further confirmed by ER overexpression and knockdown studies using various bronchoconstrictor agents. Interestingly, ERβ activation was more effective than 17β-estradiol in reducing [Ca²⁺]_i responses in the presence of TNF-α or IL-13, while no observable changes were noticed with PPT in the presence of either cytokine. The [Ca²⁺]_i-reducing effects of ERβ were mediated partially via L-type calcium channel inhibition and increased Ca²⁺ sequestration by sarcoplasmic reticulum_. Overall, these data highlight the differential signaling of ERα and ERβ in ASM during inflammation. Specific ERβ activation reduces [Ca²⁺]_i in the inflamed ASM cells and is likely to play a crucial role in regulating ASM contractility, thereby relaxing airways.

RhoC/ROCK2 promotes vasculogenic mimicry formation primarily through ERK/MMPs in hepatocellular carcinoma

Vasculogenic mimicry (VM) results in the formation of an alternative circulatory system that can improve the blood supply to multiple malignant tumors, including hepatocellular carcinoma (HCC). However, the potential mechanisms of RhoC/ROCK in VM have not yet been investigated in HCC. Here, RhoC expression was upregulated in HCC tissues, especially the VM-positive (VM+) group, compared to noncancerous tissues (P < 0.01), and patients with high expression of RhoC had shorter survival times (P < 0.001). The knockdown of RhoC via short hairpin RNA (shRNA) in SK-Hep-1 cells significantly decreased VM formation and cell motility. In contrast, cell motility and VM formation were remarkably enhanced when RhoC was overexpressed in HepG2 cells. To further assess the potential role of ROCK1 and ROCK2 on VM, we stably knocked down ROCK1 or ROCK2 in MHCC97H cells. Compared to ROCK1 shRNA, ROCK2 shRNA could largely affect VM formation, cell motility and the key VM factors, as well as the epithelial-mesenchymal transition (EMT) markers in vitro and in vivo. Moreover, p-ERK, p-MEK, p-FAK, p-paxillin, MT1-MMP and MMP2 levels were clearly altered following the overexpression of RhoC, but ROCK2 shRNA had little effect on the expression of p-FAK, which indicated that RhoC regulates FAK/paxillin signaling, but not through ROCK2. In conclusion, our results show that RhoC/ROCK2 may have a major effect on VM in HCC via ERK/MMPs signaling and might be a potential therapeutic target for the treatment of HCC.

Pregnancy-associated adaptations in [Ca2+]i-dependent and Ca2+ sensitization mechanisms of venous contraction: implications in pregnancy-related venous disorders

Pregnancy is associated with significant adaptations in the maternal hemodynamics and arterial circulation, but the changes in the venous mechanisms during pregnancy are less clear. We hypothesized that pregnancy is associated with alterations in venous function, intracellular free Ca(2+) concentration ([Ca(2+)]i), and Ca(2+)-dependent mechanisms of venous contraction. Circular segments of inferior vena cava (IVC) from virgin and late pregnant (Preg, day 19) Sprague-Dawley rats were suspended between two hooks, labeled with fura-2, and placed in a cuvet inside a spectrofluorometer for simultaneous measurement of contraction and [Ca(2+)]i (fura-2 340/380 ratio). KCl (96 mM), which stimulates Ca(2+) influx, caused less contraction (35.6 ± 6.3 vs. 92.6 ± 19.9 mg/mg tissue) and smaller increases in [Ca(2+)]i (1.67 ± 0.12 vs. 2.19 ± 0.11) in Preg vs. virgin rat IVC. The α-adrenergic receptor agonist phenylephrine (Phe; 10(-5) M) caused less contraction (23.8 ± 3.4 vs. 70.9 ± 12.9 mg/mg tissue) and comparable increases in [Ca(2+)]i (1.76 ± 0.10 vs. 1.89 ± 0.08) in Preg vs. virgin rat IVC. At increasing extracellular Ca(2+) concentrations ([Ca(2+)]e) (0.1, 0.3, 0.6, 1, and 2.5 mM), KCl and Phe induced [Ca(2+)]e-contraction and [Ca(2+)]e-[Ca(2+)]i curves that were reduced in Preg vs. virgin IVC, supporting reduced Ca(2+) entry mechanisms. The [Ca(2+)]e-contraction and [Ca(2+)]e-[Ca(2+)]i curves were used to construct the [Ca(2+)]i-contraction relationship. Despite reduced contraction and [Ca(2+)]i in Preg IVC, the Phe-induced [Ca(2+)]i-contraction relationship was greater than that of KCl and was enhanced in Preg vs. virgin IVC, suggesting parallel activation of Ca(2+)-sensitization pathways. The Ca(2+) channel blocker diltiazem, protein kinase C (PKC) inhibitor GF-109203X, and Rho-kinase (ROCK) inhibitor Y27632 inhibited KCl- and Phe-induced contraction and abolished the shift in the Phe [Ca(2+)]i-contraction relationship in Preg IVC, suggesting an interplay between the decrease in Ca(2+) influx and possible compensatory activation of PKC- and ROCK-mediated Ca(2+)-sensitization pathways. The reduced [Ca(2+)]i and [Ca(2+)]i-dependent contraction in Preg rat IVC, despite the parallel rescue activation of Ca(2+)-sensitization pathways, suggests that the observed reduction in [Ca(2+)]i-dependent contraction mechanisms is likely underestimated, and that the veins without the rescue Ca(2+)-sensitization pathways could be even more prone to dilation during pregnancy. These pregnancy-associated reductions in Ca(2+) entry-dependent mechanisms of venous contraction, if occurring in human lower extremity veins and if not adequately compensated by Ca(2+)-sensitization pathways, may play a role in pregnancy-related venous disorders.

Influence of decompression sickness on vasocontraction of isolated rat vessels

Studies conducted in divers indicate that endothelium function is impaired following a dive even without decompression sickness (DCS). Our previous experiment conducted on rat isolated vessels showed no differences in endothelium-dependent vasodilation after a simulated dive even in the presence of DCS, while contractile response to phenylephrine was progressively impaired with increased decompression stress. This study aimed to further investigate the effect of DCS on vascular smooth muscle. Thirty-two male Sprague-Dawley rats were submitted to the same hyperbaric protocol and classified according to the severity of DCS: no-DCS (without clinical symptoms), mild-DCS, or severe-DCS (dead within 1 h). A control group remained at atmospheric pressure. Isometric tension was measured in rings of abdominal aorta and mesenteric arteries. Single dose contraction was assessed with KCl solution. Dose-response curves were obtained with phenylephrine and endothelin-1. Phenylephrine-induced contraction was observed in the presence of antioxidant tempol. Additionally, plasma concentrations of angiotensin II, angiotensin-converting enzyme, and thiobarbituric acid reactive substances (TBARS) were assessed. Response to phenylephrine was impaired only among mild-DCS in both vessels. Dose-response curves to endothelin-1 were impaired after mild-DCS in mesenteric and severe-DCS in aorta. KCl-induced contraction was affected after hyperbaric exposure regardless of DCS status in aorta only. These results confirm postdive vascular dysfunction is dependent on the type of vessel. It further evidenced that vascular dysfunction is triggered by DCS rather than by diving itself and suggest the influence of circulating factor/s. Diving-induced impairment of the L-type voltage-dependent Ca(2+) channels and/or influence of renin-angiotensin system is proposed.