Abstract P1077: Nicotine Compromises Metabolic Adaptation Of The Heart To Injury By Altering PHLPP Isoforms

Rationale: Cardiovascular (CV) disease remains the leading cause of death and disability in the US and worldwide and tobacco use is a major risk factor for increasing the incidence of disease. Consequently, there is a need for understanding the cardiovascular impact of systemic nicotine on cardiac physiology and heart failure progression following injury. We have demonstrated that removal of PH domain leucine-rich repeat protein phosphatase 1 (PHLPP1) increases Akt activity and protects the heart from oxidative damage, however downregulation of PHLPP2 causes damage. Preliminary data suggest that exposure to nicotine increases PHLPP1 and decreases PHLPP2 levels in the heart. Therefore, linking the direct pathogenic effects of nicotine on these cell-survival intracellular pathways such as those that utilize PHLPP1 activity needs to be rigorously examined for therapeutic efficacy and intervention.

Hypothesis: We hypothesize that exposure to high levels of nicotine will compromise the heart and increase susceptibility to ischemic injury by altering PHLPP isoform expression.

Methods: Using in vivo systems we investigated the effect of nicotine exposure on PHLPP expression and cardiomyocyte function and injury. Male and female wild-type WT (n=4) and PHLPP1 KO (n=4) mice were implanted with osmotic minipumps containing nicotine (5mg/kg/day) or saline for 7days and changes in protein and gene expression were examined. A second cohort of WT animals was exposed to nicotine (7 days) and subjected to 1 hour ischemia and 24 hours reperfusion (n=6).

Results: Following 7 days of nicotine exposure, we found PHLPP1 protein expression was significantly increased (1.7 ± 0.25 fold) and PHLPP2 significantly decreased (0.8 ± 0.04 fold) in the hearts of WT mice. However, in PHLPP1 KO mice, nicotine exposure significant increased PHLPP2 levels in the heart (1.5 ± 0.044fold). Also, we found that exposure to nicotine suppressed genes important for mitochondrial biogenesis and decreased antioxidant protein expression in the hearts of WT mice while antioxidant signaling was significantly increased in KO hearts. Following 7 days of nicotine exposure WT mice have increased infarct injury (39% ± 3.2, n=6) following 24-hour reperfusion compared to saline treated WT (31% ± 0.55, n=4) with the same area at risk. Preliminary studies found that PHLPP1 KO significantly protected the heart from ischemic injury (26% ± 0.38, n=3), however the effect in the presence of nicotine is under investigation.

Conclusions: Our data suggests that nicotine exposure has detrimental effects on the heart by altering PHLPP isoform expression which compromises oxidative signaling and increases injury. Further studies will investigate the mechanism of nicotine induced PHLPP isoform expression both in vitro and in vivo and determine whether targeting PHLPP1 could significantly impact cardiac outcome associated with nicotine use.

Cardioprotection by isosteviol derivate JC105: A unique drug property to activate ERK1/2 only when cells are exposed to hypoxia-reoxygenation

In the present study, we have investigated potential cardioprotective properties of Isosteviol analogue we recently synthesized and named JC105. Treatment of heart embryonic H9c2 cells with JC105 (10 μM) significantly increased survival of cells exposed to hypoxia‐reoxygenation. JC105 (10 μM) activated ERK1/2, DRP1 and increased levels of cardioprotective SUR2A in hypoxia‐reoxygenation, but did not have any effects on ERK1/2, DRP1 and/or SUR2A in normoxia. U0126 (10 μM) inhibited JC105‐mediated phosphorylation of ERK1/2 and DRP1 without affecting AKT or AMPK, which were also not regulated by JC105. Seahorse bioenergetic analysis demonstrated that JC105 (10 μM) did not affect mitochondria at rest, but it counteracted all mitochondrial effects of hypoxia‐reoxygenation. Cytoprotection afforded by JC105 was inhibited by U0126 (10 μM). Taken all together, these demonstrate that (a) JC105 protects H9c2 cells against hypoxia‐reoxygenation and that (b) this effect is mediated via ERK1/2. The unique property of JC105 is that selectively activates ERK1/2 in cells exposed to stress, but not in cells under non‐stress conditions.

Aerosol Characteristics and Physico-Chemical Compatibility of Combivent® (Containing Salbutamol and Ipratropium Bromide) Mixed with Three Other Inhalants: Budesonide, Beclomethasone or N-Acetylcysteine

Inhalation therapy with a nebulizer is widely used in chronic respiratory disease. Mixing inhalation solutions/suspensions for simultaneous inhalation is more convenient and might simplify the administration procedure. However, there are no data available to address the in vitro aerosol characteristics and physico-chemical compatibility of Combivent^® (containing Salbutamol and Ipratropium bromide) with other inhalation solutions/suspensions. In order to investigate the in vitro aerosol characteristics and physico-chemical compatibility of Combivent^® with Budesonide, Beclomethasone, and N-acetylcysteine, the appearance, pH, osmotic pressure, chemical stability, mass median aerodynamic diameter (MMAD), fine particles fraction (FPF), particle size corresponding to X50 (particle size, which accounts for 50% of the total cumulative percentage of volume of all particles), delivery rate, and total delivery of the mixed inhalation solution/suspension were tested. There was no change in the appearance such as a change in color or precipitation formation at room temperature. The pH, osmolality, and chemicals of the mixtures were stable for 24 h after mixing. There were no significant differences between Combivent^®, Budesonide, Beclomethasone, N-acetylcysteine, and the mixtures in MMAD, FPF, X50, the delivery rate, and the total delivery. This indicates that the mixtures were physically and chemically compatible. The mixing did not influence the particle size, distribution, or delivery compatibility of the mixtures.

Isosteviol sodium protects heart embryonic H9c2 cells against oxidative stress by activating Akt/GSK-3β signaling pathway

Oxidative stress plays a crucial role in pathogenesis of various cardiovascular diseases. Recent studies reported that isosteviol sodium (STVNa) harbor cardioprotective properties. Here, we explore the potential cardioprotective effect of STVNa on H₂ O₂ -induced oxidative stress on heart embryonic H9c2 cardiomyocytes and the underlying mechanism. We have found that STVNa pretreatment improved cell viability, nuclear morphology and prevented LDH release induced by oxidative stress. STVNa pretreatment also reduced production of reactive oxygen species, preserved mitochondrial function, restored biological antioxidant defense systems and prevented cell death. Western blotting analysis revealed that STVNa regulated the mitochondrial related pro- and anti-apoptotic protein (Bax and Bcl-2 respectively) levels, increased phosphorylation of Akt (ser473) and GSK-3β (ser9) and promoted binding between HK-II and mitochondria under the normal or oxidative stress conditions. LY294002, a PI3K inhibitor, abolished cytoprotective effects of STVNa by inhibiting activation of Akt and GSK-3β. Based on these findings, we conclude that STVNa protects H9c2 cells against oxidative stress by activating Akt/GSK-3β signaling pathway, which, in turn, leads to recruitment of HK-II to mitochondria and regulating Bcl2/Bax levels.

Exposure to 15% oxygen in vivo up-regulates cardioprotective SUR2A without affecting ERK1/2 and AKT: a crucial role for AMPK

SUR2A is an 'atypical' ABC protein that forms sarcolemmal ATP-sensitive K⁺ (K_ATP ) channels by binding to inward rectifier Kir6.2. Manipulation with SUR2A levels has been suggested to be a promising therapeutic strategy against ischaemic heart diseases and other diseases where increased heart resistance to stress is beneficial. Some years ago, it has been reported that high-altitude residents have lower mortality rates for ischaemic heart disease. The purpose of this study was to determine whether SUR2A is regulated by mild-to-severe hypoxic conditions (15% oxygen; oxygen tension equivalent to 3000 m above sea level) and elucidate the underlying mechanism. Mice were exposed to either to 21% (control) or 15% concentration of oxygen for 24 hrs. Twenty-four hours long exposure to 15% oxygen decreased partial pressure of O2 (PO₂ ), but did not affect blood CO₂ (PCO₂ ), haematocrit nor levels of ATP, lactate and NAD+/NADH in the heart. Cardiac SUR2A levels were significantly increased while Kir6.2 levels were not affected. Hypoxia did not induce phosphorylation of extracellular signal-regulated kinases (ERK1/2) or protein kinase B (Akt), but triggered phosphorylation of AMP activated protein kinase (AMPK). AICAR, an activator of AMPK, increased the level of SUR2A in H9c2 cells. We conclude that oxygen increases SUR2A level by activating AMPK. This is the first account of AMPK-mediated regulation of SUR2A.

Arsenic and human health effects: A review

Arsenic (As) is ubiquitous in nature and humans being exposed to arsenic via atmospheric air, ground water and food sources are certain. Major sources of arsenic contamination could be either through geological or via anthropogenic activities. In physiological individuals, organ system is described as group of organs that transact collectively and associate with other systems for conventional body functions. Arsenic has been associated with persuading a variety of complications in body organ systems: integumentary, nervous, respiratory, cardiovascular, hematopoietic, immune, endocrine, hepatic, renal, reproductive system and development. In this review, we outline the effects of arsenic on the human body with a main focus on assorted organ systems with respective disease conditions. Additionally, underlying mechanisms of disease development in each organ system due to arsenic have also been explored. Strikingly, arsenic has been able to induce epigenetic changes (in utero) and genetic mutations (a leading cause of cancer) in the body. Occurrence of various arsenic induced health effects involving emerging areas such as epigenetics and cancer along with their respective mechanisms are also briefly discussed.

Mild hypoxia in vivo regulates cardioprotective SUR2A: A role for Akt and LDH

High-altitude residents have lower mortality rates for ischaemic heart disease and this is ascribed to cardiac gene remodelling by chronic hypoxia. SUR2A is a cardioprotective ABC protein serving as a subunit of sarcolemmal ATP-sensitive K⁺ channels. The purpose of this study was to determine whether SUR2A is regulated by mild hypoxia in vivo and to elucidate the underlying mechanism. Mice were exposed to either 21% (control) or 18% (mild hypoxia) oxygen for 24 h. Exposure to 18% oxygen did not affect partial pressure of O₂ (PO₂) and CO₂ (PCO₂) in the blood, haematocrit or level of ATP in the heart. However, hypoxia increased myocardial lactate dehydrogenase (LDH) and lactate as well as NAD⁺ without affecting total NAD. SUR2A levels were significantly increased as well as myocardial resistance to ischaemia–reperfusion. Exposure to 18% oxygen did not phosphorylate extracellular signal regulated kinases (ERK1/2) or AMP activated protein kinase (AMPK), but it phosphorylated protein kinase B (Akt). An inhibitor of phosphoinositide 3-kinases (PI3K), LY294002 (0.2 mg/mouse), abolished all observed effects of hypoxia. LDH inhibitors, galloflavin (50 μM) and sodium oxamate (80 mM) significantly decreased levels of SUR2A in heart embryonic H9c2 cells, while inactive mutant LDH form, gly193-M-LDH increased cellular sensitivity towards stress induced by 2,4-dinitrophenol (10 mM). Treatment of H9c2 cells with sodium lactate (30 mM) increased intracellular lactate, but did not affect LDH activity or SUR2A levels. We conclude that PI3K/Akt signalling pathway and LDH play a crucial role in increase of cardiac SUR2A induced by in vivo exposure to 18% oxygen.

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Mild hypoxia increases levels of cardioprotective SUR2A in the heart.

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Phosphorylation of Akt mediates mild hypoxia-induced increase in SUR2A.

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Phosphorylation of ERK1/2 and AMPK is not involved in observed increase in SUR2A.

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PI3K/Akt target LDH to regulate SUR2A levels in the myocardium.

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LDH mediates regulation of SUR2A in a lactate-independent manner.

Upregulation of cardioprotective SUR2A by sub-hypoxic drop in oxygen

The effects of hypoxia on gene expression have been vigorously studied, but possible effects of small changes in oxygen tension have never been addressed. SUR2A is an atypical ABC protein serving as a regulatory subunit of sarcolemmal ATP-sensitive K⁺ (K_ATP) channels. Up-regulation of SUR2A is associated with cardioprotection and improved physical endurance. Here, we have found that a 24 h-long exposure to slightly decreased ambient fractional concentration of oxygen (20% oxygen), which is an equivalent to oxygen tension at 350 m above sea level, significantly increased levels of SUR2A in the heart despite that this drop of oxygen did not affect levels of O₂, CO₂ and hematocrit in the blood or myocardial levels of ATP, lactate and NAD/NADH/NAD⁺. Hearts from mice exposed to 20% oxygen were significantly more resistant to ischaemia-reperfusion when compared to control ones. Decrease in fractional oxygen concentration of just 0.9% was associated with phosphorylation of ERK1/2, but not Akt, which was essential for up-regulation of SUR2A. These findings indicate that a small drop in oxygen tension up-regulates SUR2A in the heart by activating ERK signaling pathway. This is the first report to suggest that a minimal change in oxygen tension could have a profound signaling effect.

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Mice were exposed for 24 h to 20% oxygen (oxygen tension at sea level is 20.9%).

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Exposure to 20% oxygen did not produce measurable in vivo signs of hypoxia.

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However, 20% of oxygen up-regulated cardioprotective SUR2A.

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Phosphorylation of ERK1/2, but not Akt, mediated observed increase in SUR2A.

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Thus, a small drop in oxygen up-regulates cardiac SUR2A by activating ERK1/2.

Functional significance of long non-coding RNAs in breast cancer

Most of the genome is transcribed to transcripts of no protein-coding potential. However, these transcripts do not represent transcriptional 'noise', rather they play an important role in cellular metabolism and development. Non-coding transcripts of 200 bases to 100 kb length are termed as long non-coding RNAs, majority of which are yet to be characterised thoroughly. Long non-coding RNAs (lncRNAs) play a significant role in cellular process ranging from transcriptional to post-transcriptional regulation. In this review, we highlight the recent efforts to characterise the major functions of lncRNAs in breast cancer. lncRNA expression is altered in several cancer types. Further, the aberrant regulation of lncRNAs promotes tumour development as they are involved in several cancer-associated pathways.

KATP channels are up-regulated with increasing age in human myometrium

It is well established that ageing is associated with decrease in myometrial efficiency and higher incidence of labour complications. In myometrium, the presence of ATP-sensitive K+ (KATP) channels has been detected and they could be a factor in regulating uterine quiescence in pregnancy and contractions during labour. Here, we have examined a possibility of ageing-mediated regulation of KATP channels in the human myometrium. Myometrial samples were taken from non-pregnant women undergoing hysterectomy (n=34) and from women undergoing caesarean section in late pregnancy (n=36). Real time RT-PCR revealed that mRNAs of all known KATP channel subunits were present in the human myometrium. In non-pregnant myometrium, ageing up-regulated SUR2B/Kir6.1, subunits forming KATP channels in this tissue, without affecting the expression of other channel subunits. In the late pregnant myometrium, the level of subunits that do not form functional KATP channels was not affected by age within 20-41 age range. However, uterine SUR2B and Kir6.1 were up-regulated in parturient over 35 years. An ageing-induced increase in those channel subunits was confirmed by Western blotting. Thus, this study suggests that KATP channels are up-regulated with increasing age in human myometrium. This may help explain, at least partially, increased rate of birth complications in women aged over 35 years.