p27 Protein Protects Metabolically Stressed Cardiomyocytes from Apoptosis by Promoting Autophagy

p27^Kip1 (p27), a key regulator of cell division, has been implicated in autophagy of cancer cells. However, its role in autophagy, the evolutionarily conserved catabolic process that enables cells to remove unwanted proteins and damaged organelles, had not been examined in the heart. Here we report that ectopic delivery of a p27 fusion protein (TAT-p27) was sufficient to induce autophagy in neonatal rat ventricular cardiomyocytes in vitro, under basal conditions and after glucose deprivation. Conversely, lentivirus-delivered shRNA against p27 successfully reduced p27 levels and suppressed basal and glucose-deprived levels of autophagy in cardiomyocytes in vitro. Glucose deprivation mimics myocardial ischemia and induces apoptosis in cardiomyocytes. During glucose deprivation, TAT-p27 inhibited apoptosis, whereas down-regulation of p27 decreased survival of cardiomyocytes. However, inhibition of autophagy by pharmacological (3-methyladenine, chloroquine, or bafilomycin A1) or genetic approaches (siRNA-mediated knockdown of Atg5) sensitized cardiomyocytes to glucose deprivation-induced apoptosis, even in the presence of TAT-p27. TAT-p27 was also able to provoke greater levels of autophagy in resting and fasting cardiomyocytes in vivo. Further, TAT-p27 enhanced autophagy and repressed cardiomyocytes apoptosis, improved cardiac function, and reduced infarct size following myocardial infarction. Again, these effects were lost when cardiac autophagy in vivo was blocked by chloroquine. Taken together, these data show that p27 positively regulates cardiac autophagy in vitro and in vivo, at rest and after metabolic stress, and that TAT-p27 inhibits apoptosis by promoting autophagy in glucose-deprived cardiomyocytes in vitro and in post-myocardial infarction hearts in vivo.     

Hemodynamic assessment of pulmonary hypertension in mice: a model-based analysis of the disease mechanism

Biomechanics and Modeling in Mechanobiology - This study uses a one-dimensional fluid dynamics arterial network model to infer changes in hemodynamic quantities associated with pulmonary...     

Cell-Shape Regulation of Smooth Muscle Cell Proliferation

Vascular smooth muscle cells (SMCs) play an important role in vascular remodeling. Heterogeneity and phenotypic changes in SMCs are usually accompanied by a morphological difference, i.e., elongated/spindle-like versus spread-out or epithelioid/rhomboid cell shapes. However, it is not known whether the cell shape directly regulates SMC proliferation, and what the underlying mechanisms are. In this study, microgrooves and micropatterned matrix islands were used to engineer the cell shape and investigate the associated biophysical and biological mechanisms. Compared to spread-out SMCs on nonpatterned surfaces, SMCs on micropatterned surfaces demonstrated elongated morphology, significantly lower cell and nucleus shape indexes, less spreading, a lower proliferation rate, and a similar response (but to a lesser extent) to platelet-derived growth factor, transforming growth factor-β, and mechanical stretching. DNA microarray profiling revealed a lower expression of neuron-derived orphan receptor-1 (NOR-1) in elongated SMCs. Knocking down NOR-1 suppressed DNA synthesis in SMCs, suggesting that NOR-1 is a mediator of cell elongation effects. Regulation of DNA synthesis in SMCs by the cell shape alone and a decrease in DNA synthesis in the case of small cell spreading area were achieved by micropatterning SMCs on matrix islands of different shapes and spreading areas. Changes in the cell shape also affected the nucleus shape, whereas variations in the cell spreading area modulated the nucleus volume, indicating a possible link between nucleus morphology (both shape and volume) and DNA synthesis. The findings of this investigation provide insight into cell shape effects on cell structure and proliferation, and have direct implications for vascular pathophysiology.     

Triggering Receptor Expressed on Myeloid Cells 1 (TREM-1)-mediated Bcl-2 Induction Prolongs Macrophage Survival

Triggering receptor expressed on myeloid cells 1 (TREM-1) is a superimmunoglobulin receptor expressed on myeloid cells that plays an important role in the amplification of inflammation. Recent studies suggest a role for TREM-1 in tumor-associated macrophages with relationship to tumor growth and progression. Whether the effects of TREM-1 on inflammation and tumor growth are mediated by an alteration in cell survival signaling is not known. In these studies, we show that TREM-1 knock-out macrophages exhibit an increase in apoptosis of cells in response to lipopolysaccharide (LPS) suggesting a role for TREM-1 in macrophage survival. Specific ligation of TREM-1 with monoclonal TREM-1 (mTREM-1) or overexpression of TREM-1 with adeno-TREM-1 induced B-cell lymphoma-2 (Bcl-2) with depletion of the key executioner caspase-3 prevents the cleavage of poly(ADP-ribose) polymerase. TREM-1 knock-out cells showed lack of induction of Bcl2 with an increase in caspase-3 activation in response to lipopolysaccharide. In addition overexpression of TREM-1 with adeno-TREM-1 led to an increase in mitofusins (MFN1 and MFN2) and knockdown of TREM-1 decreased the expression of mitofusins suggesting that TREM-1 contributes to the maintenance of mitochondrial integrity favoring cell survival. Investigations into potential mechanisms by which TREM-1 alters cell survival showed that TREM-1-induced Bcl-2 in an Egr2-dependent manner. Furthermore, our data shows that expression of Egr2 in response to specific ligation of TREM-1 is ERK mediated. These data for the first time provide novel mechanistic insights into the role of TREM-1 as an anti-apoptotic protein that prolongs macrophage survival.     

Effects of nickel toxicity on morphological and physiological aspects of osmoregulation in <Emphasis Type="Italic">Typha domingensis</Emphasis> (<Emphasis Type="Italic">Typhaceae</Emphasis>) populations

The present work examined morphological and physiological aspects of osmoregulation in some differently adapted populations of Typha domingensis. Six populations of T. domingensis were grown in waterlogged conditions under four levels of nickel (0, 50, 100 and 1500 mg/kg of Ni). The Ni tolerance was explored on the basis of different characteristics of shoots. Along with the increasing level of Ni stress, all populations showed an increment of proline and glycinebetaine content, low photosynthetic and transpiration rates and decreased chlorophyll content. Analyzed morphological parameters revealed possible adaptations to deal with Ni stress. The less tolerant Sahianwala population produced more aerenchyma, less accumulation of osmolytes and reduced shoot fresh weight under Ni stress than the tolerant ones. Our results suggested that T. domingensis has the capacity to survive under Ni stress and could be used for the absorption of toxic metal ions from industrially polluted water.     

Introducing a novel method based on the imperialistic competitive algorithm to determine fluorine intermolecular potential from ab initio calculations and calculation of some properties via MD simulations

In this work, the possibility of obtaining an accurate site-site potential model suitable for use in molecular dynamics (MD) simulations of fluorine from ab initio calculations has been explored. The exploration was made on ab initio calculations. To reduce the ab initio pair potentials into a site-site potential, a higher significance was assigned to the configuration which is more stable. For this purpose, the imperialistic competitive algorithm (ICA) was implemented as a powerful optimisation tool. The calculated second virial coefficients were compared to the experimental values to test the quality of the presented intermolecular potential. The relative error for the calculated second virial coefficient ranged from 0.1 to 5.6%. MD simulations were used to evaluate the ability of the proposed intermolecular potential function. The relative error for the MD simulations ranged from 0.5 to 5.2%. The results are in good agreement with experimental data.     

An angiotensin I-converting enzyme insertion/deletion polymorphism is associated with Pakistani asthmatic cases and controls

Asthma is a chronic disease due to inflammation of the airways of lungs that is clinically characterized by variable symptoms including wheezing, coughing and shortness of breath. Angiotensin I-converting enzyme (ACE) plays a major role in fibrous tissue formation and is highly expressed in lungs. The main aim of this research work was to study the role of ACE insertion/deletion (I/D) polymorphism, rs4646994, in asthma in Pakistani patients. A total of 854 subjects, including 333 asthma patients and 521 ethnically matched controls, were studied. The ACE (I/D) polymorphism was genotyped using polymerase chain reaction (PCR). Chi-square, Fisher’s exact and Hardy–Weinberg equilibrium tests were used to compare groups. Homozygous insertion genotype II (p<0.0001, OR=3.38) and insertion allele (I) was significantly more frequent in Pakistani asthmatics than in healthy controls (p=0.0007, OR=1.40). The ID genotype (p<0.0001, OR=0.43) and the deletion allele (D) were associated with protection of disease in Pakistani patients (p=0.0007, OR=0.71). These data suggest the involvement of ACE I/D polymorphism in asthma risk in the Pakistani population. This marker may be an important indication in the molecular mechanism of asthma and can become a useful tool in risk assessment and help in designing strategy to combat disease.     

The role of selenium in amelioration of heat-induced oxidative damage in cucumber under high temperature stress

High temperature is an environmental stress which destroys agricultural crops and inhibits their growth and productivity. The aim of current investigation was to examine the role of selenium (Se) on cucumber (Cucumis sativus L.) cv. Sahil plant growth, physio-biochemical and yield attributes under heat stress (HS) in controlled conditions. Plants were grown under normal temperature (NT; 28/18 °C day/night) from sowing to 32 days after sowing (DAS). All plants were foliar-sprayed with Se (8 µM) at flower-initiation stage (32-DAS) and heat stress (HS; 40/30 °C day/night) was induced from 35-DAS to entire duration of the experiment (75-DAS). Data regarding growth, physio-biochemical and yield traits were measured. Heat stress decreased growth traits, total chlorophyll contents, chlorophyll fluorescence parameters, photosynthesis (Pn), stomatal conductance (g _s), transpiration rate (E), antioxidant enzyme activities, membrane stability index (MSI) and yield-related attributes, while increased intercellular CO₂ (Ci), ROS production, lipid peroxidation (LPO), non-photochemical quenching (NPQ) and compatible solutes. Exogenous application of Se mitigated HS-induced injurious effects by improving growth components, Pn, g _s, E, chlorophyll content, chlorophyll fluorescence parameters, antioxidant enzyme activities, level of osmolytes, MSI and yield attributes and reducing ROS, LPO and NPQ. Selenium reversed heat-induced oxidative damage by strengthening antioxidative mechanism, which resulted in higher scavenging of ROS, thereby minimizing LPO. It is suggested that Se-induced improvement in Pn, growth and productivity associated traits under HS is linked with enhanced antioxidant activities and osmolytes accumulation. In addition, Se applied at flower initiation is highly effective in alleviating heat damage in cucumber.