BackgroundExposure of vascular smooth muscle cells (VSMCs) to excessive cyclic stretch such as in hypertension causes a shift in their phenotype. The focal adhesion protein zyxin can transduce such biomechanical stimuli to the nucleus of both endothelial cells and VSMCs, albeit with different thresholds and kinetics. However, there is no distinct vascular phenotype in young zyxin-deficient mice, possibly due to functional redundancy among other gene products belonging to the zyxin family. Analyzing zyxin function in VSMCs at the cellular level might thus offer a better mechanistic insight. We aimed to characterize zyxin-dependent changes in gene expression in VSMCs exposed to biomechanical stretch and define the functional role of zyxin in controlling the resultant VSMC phenotype.Methods and ResultsDNA microarray analysis was used to identify genes and pathways that were zyxin regulated in static and stretched human umbilical artery–derived and mouse aortic VSMCs. Zyxin-null VSMCs showed a remarkable shift to a growth-promoting, less apoptotic, promigratory and poorly contractile phenotype with ≈90% of the stretch-responsive genes being zyxin dependent. Interestingly, zyxin-null cells already seemed primed for such a synthetic phenotype, with mechanical stretch further accentuating it. This could be accounted for by higher RhoA activity and myocardin-related transcription factor-A mainly localized to the nucleus of zyxin-null VSMCs, and a condensed and localized accumulation of F-actin upon stretch.ConclusionsAt the cellular level, zyxin is a key regulator of stretch-induced gene expression. Loss of zyxin drives VSMCs toward a synthetic phenotype, a process further consolidated by exaggerated stretch.

Aloe vera is a semi-tropical plant of Liliaceae family which has a wide range of applications in traditional medicine. In the present study, we sought to investigate the heptaoprotective potential of Aloe vera gel as a diet supplement. To achieve this goal, we have designed in vitro and in vivo experimental models of chemical-induced liver damage using male Sprague-Dawley rat. In the in vitro model, its effect was evaluated on Fenton's reaction-induced liver lipid peroxidation. Co-incubation with gel significantly reduced the generation of liver lipid peroxide (LPO). Next, to see the similar effect in vivo, gel was orally administered to rats once daily for 21 successive days. Following 1 hour of the last administration of gel, rats were treated with intra-peritoneal injection of CCl4. Dietary gel showed significant hepatoprotection against CCl4-induced damage as evident by restoration of liver LPO, serum transaminases, alkaline phosphatase, and total bilirubin towards near normal. The beneficial effects were pronounced with the doses used (400 and 800 mg/kg body weight). Besides, we did not observe any significant drop in serum albumin, globulin as well as total protein levels of gel-administered rats. Histopathology of the liver tissue further supported the biochemical findings confirming the hepatoprotective potential of dietary gel.

Arterial hypertension causes left ventricular hypertrophy leading to dilated cardiomyopathy. Following compensatory cardiomyocyte hypertrophy, cardiac dysfunction develops due to loss of cardiomyocytes preceded or paralleled by cardiac fibrosis. Zyxin acts as a mechanotransducer in vascular cells that may promote cardiomyocyte survival. Here, we analyzed cardiac function during experimental hypertension in zyxin knockout (KO) mice. In zyxin KO mice, made hypertensive by way of deoxycorticosterone acetate (DOCA)-salt treatment telemetry recording showed an attenuated rise in systolic blood pressure. Echocardiography indicated a systolic dysfunction, and isolated working heart measurements showed a decrease in systolic elastance. Hearts from hypertensive zyxin KO mice revealed increased apoptosis, fibrosis and an upregulation of active focal adhesion kinase as well as of integrins α5 and β1. Both interstitial and perivascular fibrosis were even more pronounced in zyxin KO mice exposed to angiotensin II instead of DOCA-salt. Stretched microvascular endothelial cells may release collagen 1α2 and TGF-β, which is characteristic for the transition to an intermediate mesenchymal phenotype, and thus spur the transformation of cardiac fibroblasts to myofibroblasts resulting in excessive scar tissue formation in the heart of hypertensive zyxin KO mice. While zyxin KO mice per se do not reveal a cardiac phenotype, this is unmasked upon induction of hypertension and owing to enhanced cardiomyocyte apoptosis and excessive fibrosis causes cardiac dysfunction. Zyxin may thus be important for the maintenance of cardiac function in spite of hypertension.

No abstract

The in vitro oxidative stress induced by ethanol/Fenton's reaction in rat liver homogenates decreased significantly in the presence of Syzygium cumini seed extract, suggesting the protective effect of the seed extract against the oxidative stress in liver. To corroborate the in vitro effects by an in vivo experiment, 24 rats were divided into four groups: control, S. cumini seed-extract-administered (SE), 15% ethanol-fed (Alc) and Alc+SE rats. The oral administration of the extract (400 mg/kg BW.day) for 7 weeks significantly decreased the levels of liver LPO in the Alc+SE rats, suggesting that S. cumini seed not only obstructed the in vitro free radical production and subsequent oxidative stress, but also inhibited their in vivo formation. The oral administration of extract also reduced the enzyme activities of serum gammaglutamyl transferase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase and the levels of serum creatinine and blood urea nitrogen, serum/liver triglycerides and total cholesterol of the alcoholic rats. The levels of fecal cholesterol were increased by the extract. Fatty degenerations in liver and kidney were absent with S. cumini seed extract treatment. The results suggest that S. cumini seed may be a potential therapy for alcoholics and related dysfunctions by restraining oxidative stress.