nary arterial hypertension (PAH) is a devastating disease affecting lung vasculature. The pulmonary arteries become occluded due to increased proliferation and suppressed apoptosis of the pulmonary artery smooth muscle cells (PASMCs) within the vascular wall. It was recently shown that DNA damage could trigger this phenotype by upregulating poly(ADP-ribose)polymerase 1 (PARP-1) expression, although the exact mechanism remains unclear. In silico analyses and studies in cancer demonstrated that microRNA miR-223 targets PARP-1. We thus hypothesized that miR-223 downregulation triggers PARP-1 overexpression, as well as the proliferation/apoptosis imbalance observed in PAH. We provide evidence that miR-223 is downregulated in human PAH lungs, distal PAs, and isolated PASMCs. Furthermore, using a gain and loss of function approach, we showed that increased hypoxia-inducible factor 1␣, which is observed in PAH, triggers this decrease in miR-223 expression and subsequent overexpression of PARP-1 allowing PAH-PASMC proliferation and resistance to apoptosis. Finally, we demonstrated that restoring the expression of miR-223 in lungs of rats with monocrotaline-induced PAH reversed established PAH and provided beneficial effects on vascular remodeling, pulmonary resistance, right ventricle hypertrophy, and survival. We provide evidence that miR-223 downregulation in PAH plays an important role in numerous pathways implicated in the disease and restoring its expression is able to reverse PAH. miR-223; pulmonary hypertension; PARP-1; HIF-1␣; DNA damage PULMONARY ARTERIAL HYPERTENSION (PAH) is a serious condition characterized by obstruction of the precapillary pulmonary arterioles (PA) due to excessive vasoconstriction, inflammation, and imbalance between cells' proliferation and apoptosis within the arterial wall. This remodeling and obstruction of the PAs leads to increases in pulmonary vascular resistance, right ventricular (RV) failure, and death of patients. Despite recent therapeutic advances, most patients exhibit persistently poor exercise capacity and quality of life, with a 3-yr survival rate of 65% (12).Growing evidence underlines the importance of DNA damage in PAH etiology (9,19,23). Indeed, the sustained inflammation, RAGE expression (21), and metabolic stress (30) observed in PAH result in DNA damage-dependent activation of poly(ADP-ribose)polymerase 1 (PARP-1) in PA smooth muscle cells (PASMCs) of PAH patients (23). We recently showed that PARP-1 overexpression was responsible for enhanced PAH-PASMC proliferation and suppressed apoptosis (23). Nevertheless, the mechanisms that regulate this overexpression in PAH remain elusive.In cancer, PARP-1 expression is regulated by microRNA-223 (miR-223), a microRNA involved in DNA damage response (34). According to TargetScan 6.2, PARP-1 is in fact a predicted target of miR-223. Moreover, downregulation of miR-223 has been shown to mediate mechanical stretch-stimulated proliferation of vascular smooth muscle cells (33). Interestingly, Wang et al. (38) reported that miR-...

Among the causes, modifications of the mitochondrial function could be of major importance. Polyunsaturated fatty (-3) acids have been shown to play a role in intracellular functions. We hypothesize that docosahexaenoic acid (DHA) supplementation could improve muscle mitochondrial function that could contribute to limit the early consequences of aging on adult muscle. Twelve-month-old male Wistar rats were fed a low-polyunsaturated fat diet and were given DHA (DHA group) or placebo (control group) for 9 wk. Rats from the DHA group showed a higher endurance capacity (ϩ56%, P Ͻ 0.05) compared with control animals. Permeabilized myofibers from soleus muscle showed higher O2 consumptions (P Ͻ 0.05) in the DHA group compared with the control group, with glutamate-malate as substrates, both in basal conditions (i.e., state 2) and under maximal conditions (i.e., state 3, using ADP), along with a higher apparent Km for ADP (P Ͻ 0.05). Calcium retention capacity of isolated mitochondria was lower in DHA group compared with the control group (P Ͻ 0.05). Phospho-AMPK/AMPK ratio and PPAR␦ mRNA content were higher in the DHA group compared with the control group (P Ͻ 0.05). Results showed that DHA enhanced endurance capacity in adult animals, a beneficial effect potentially resulting from improvement in mitochondrial function, as suggested by our results on permeabilized fibers. DHA supplementation could be of potential interest for the muscle function in adults and for fighting the decline in exercise tolerance with age that could imply energy-sensing pathway, as suggested by changes in phospho-AMPK/AMPK ratio. polyunsaturated fatty acids; isolated mitochondria; permeabilized myofibers; muscle bioenergetics AGING IS ASSOCIATED WITH A PROGRESSIVE DECREASE in muscle mass and alterations in muscle function leading to reduced physical abilities, exercise performance and quality of life, and ultimately disabilities (21,26,36). Among the causes of such sarcopenia, inadequate protein synthesis matching protein degradations is of major importance (4, 12). Also, changes in metabolism could be part of the muscle mass decrease with age.

The aim of this study was to characterize the early alterations of the liver mitochondrial function in ZDF (fa/fa) rats that develop diabetes compared to that of their lean counterparts ZDF (fa/+). Liver mitochondrial function was examined in 11‐ and 14‐week‐old ZDF (fa/fa) and ZDF lean (fa/+) rats. Oxygen consumption, H2O2 release, calcium retention capacity (CRC), membrane potential, membrane fluidity, and fatty acid composition were analyzed. State 3 oxygen consumption with palmitoyl‐carnitine increases between 11 and 14 weeks of age in lean but not in diabetic animals. This response was not seen with other substrates, suggesting that the use of fatty acids is impaired in diabetic rats. H2O2 release was lower in 14‐week‐old ZDF (fa/fa) rats as compared to ZDF lean (fa/+). These changes were not associated with differences in enzymatic activities of the respiratory complexes, suggesting regulatory mechanisms independent of their expression levels. Membrane fluidity and composition analyses show only slight effects linked to diabetes progression. The most salient feature was a reduction in CRC in the presence of CsA, an effect reflecting PTP dysregulation. Our data suggest few changes of mitochondrial function in ZDF fa/fa rats. At the age of 11 weeks, liver mitochondria have mainly a reduced effect of CsA on CRC.

Background: Coronary artery stenosis is characterized by coronary artery smooth muscle cell (CoASMC) proliferation and survival in detrimental conditions (increased inflammation, oxidized lipids, shear stress) known to cause DNA damage. In cancer, increased cell proliferation was attributed to DNA damage signaling activation secondary to mitochondrial/metabolic dysfunction. This leads to the upregulation of Poly(ADP)ribose-polymerase 1 (PARP-1), a critical enzyme acting as a DNA damage sensor, and the epigenetic reader Bromodomain-containing protein 4 (BRD4), both known to contribute to cell survival and proliferation. In light of these observations, we hypothesized that impaired mitochondria/metabolism triggers DNA damage signaling in coronary artery stenosis leading to CoASMC proliferation and thus vessel narrowing. Method/Results: Primary cultured human CoASMC from patients with stenosis (n=3) exhibit signs of mitochondrial dysfunction including hyperpolarization (TMRM; n=3, p<0.05), downregulation metabolic sensors Sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor coactivator 1 (PGC1-α) expression (western blot (WB); n=3, p<0.05). These cells also exhibit enhanced glycolysis compared to control hCoASMC (Seahorse Bioscience XF24e; n=3, p<0.05). These mitochondrial/metabolic abnormalities enhance DNA damage signaling in human coronary arteries with stenosis (53BP1; n=8, p<0.05), as well as PARP-1 and BRD4 expression (WB; n=4, p<0.05) compared to control arteries. This pathogenic phenotype is also present in isolated hCoASMC issued from stenosis, as they have more DNA damage sites (γH2AX; n=5, p<0.05) and exhibit increased PARP-1 and BRD4 expression (WB; n=4, p<0.05) compared to control hCoASMC. PARP-1 and BRD4 activation in pathologic hCoASMC promote proliferation (Ki67; n=5, p<0.05) by downregulating cell cycle inhibitors p300 and p21 (WB; n=3, p<0.05), leading to cell survival (MTT assay; n=3, p<0.05). This pathological phenotype was reversed upon treatment with a PARP-1 (Veliparib, 10μM) or a BRD4 (JQ1, 1μM) inhibitor. Conclusion: Our study suggests an important role for BRD4 signaling and metabolic disorder in coronary diseases and opens the door to new avenues of investigation and treatment.

Chronic obstructive pulmonary disease (COPD) is associated with patientˈs muscle mass loss and exercise intolerance. An oral supplementation with omega‐3 polyunsaturated fatty acids has been shown to increase exercise capacity in COPD patients. To understand the underlying mechanisms, we studied the effect of docosahexaenoic acid (DHA) oral administration on the muscle function of animals chronically exposed to hypoxia (FiO2 12%) for 3 weeks. Endurance time increased by 210 % in animals under Hypoxia+DHA compared to animals under Hypoxia alone. DHA supplementation preserves the soleus and plantaris muscle masses under Hypoxia despite a similar decrease in total body weight compared to Hypoxia. Oxygen consumption by muscle fibers from soleus using complex I substrate is similar in DHA+Hypoxia and in control (Normoxia) groups but lower in Hypoxia group. This effect of DHA is not seen in white gastrocnemius muscle fibers. Maximal activities and expression levels of respiratory chain complexes are differently affected by Hypoxia and Hypoxia+DHA conditions, suggesting that mitochondria are sensitive to DHA supplementation. These alterations could contribute to the greater exercise tolerance and the muscle mass preservation reported that could justify the use of DHA in patients with muscle mass loss. Further studies are necessary to characterize the action mechanism of DHA on hypoxia‐induced alterations.

INTRODUCTIONHuman and animal pulmonary arterial hypertension (PAH) is characterized by a selective activation of several transcription factors including STAT3, NFAT and HIF‐1α, which regulates pulmonary artery smooth muscle cells (PASMC) proliferation and apoptosis. The activation mechanisms of these factors in PAH remain elusive. Hsp90 is a major molecular chaperone that is plays a pivotal role in assisting correct folding and functionality of its client proteins. The Hsp90 client proteins include a wide variety of transcription factors like NFAT, STAT3 and HIF‐1α. Recent evidences have shown that miR‐223 may regulates HsP90 expression in cancer, which share many similarities with PAH. We thus hypothesized that the miR‐223/Hsp90 axis is aberrantly expressed in PAH patients, contributing to PAH‐PASMC phenotype.METHODS and RESULTSUsing immunoblot, we showed that Hsp90 is upregulated in lungs, and PASMC of PAH patients compared to non‐PAH donors. This upregulation in Hsp90 is associated with a significant downregulation of miR223 in PAH; upregulation of HIF‐1α, NFAT and STAT3 activation measured by immunoblot and nuclear translocation assay. In primary cultured PASMC from 3 PAH and 3 control patients, we demonstrated that miR‐223 upregulation using mimic or Hsp90 molecular inhibition using siRNAs significantly reduces PAH‐PASMC proliferation and resistance to apoptosis. Finally, using monocrotaline‐induced PAH, we showed that miR223 nebulization decreases total pulmonary resistance by decreasing distal PA wall thickness.CONCLUSIONThe miR223/Hsp90 may represent a new signal hub in PAH, accounting for the activation of several transcription factors contributing to PAH‐PASMC phenotype and thus vascular remolding seen in PAH.

We studied the alterations of the mitochondrial function in response to various hypercaloric diets, and their relation with the occurrence of obesity and/or metabolic syndrome. Male Wistar rats were fed with either standard diet (Control), High‐Fructose (HF) or High‐Fat/High Sucrose (HF/HS) for 6 weeks. Rats under HF/HS displayed increase in body weight, insulin resistance, liver steatosis, and in visceral adiposity when compared to control. In HF/HS, TBARs, AOPP, and antioxidative enzymes were higher in plasma and muscle when compared to control. HF diet but not HF/HS diet was associated to a lower oxygen consumption by liver isolated mitochondria under non phosphorylating conditions whatever the substrate used excepting palmitoyl‐carnitine, compared to control (−30 to −60%). We also report a higher citrate synthase activity in liver tissue in the same condition (+53%) compared to control diet. Activities of complexes II and III are lower in HF and in HF/HS compared to control. H2O2 release by liver isolated mitochondria was higher in HF with succinate as a substrate, compared to the control suggesting alterations of both complex I and III. These results suggest that the type of diet has different effects on mitochondrial function that could related to the obesity and insulin resistance states.This work was supported by the French Agence Nationale pour la Recherche (ANR : project MitHyCal).

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