Age-dependent increase of oxidative stress regulates microRNA-29 family preserving cardiac health.

The short-lived turquoise killifish Nothobranchius furzeri (Nfu) is a valid model for aging studies. Here, we investigated its age-associated cardiac function. We observed oxidative stress accumulation and an engagement of microRNAs (miRNAs) in the aging heart. MiRNA-sequencing of 5 week (young), 12-21 week (adult) and 28-40 week (old) Nfu hearts revealed 23 up-regulated and 18 down-regulated miRNAs with age. MiR-29 family turned out as one of the most up-regulated miRNAs during aging. MiR-29 family increase induces a decrease of known targets like collagens and DNA methyl transferases (DNMTs) paralleled by 5´methyl-cytosine (5mC) level decrease. To further investigate miR-29 family role in the fish heart we generated a transgenic zebrafish model where miR-29 was knocked-down. In this model we found significant morphological and functional cardiac alterations and an impairment of oxygen dependent pathways by transcriptome analysis leading to hypoxic marker up-regulation. To get insights the possible hypoxic regulation of miR-29 family, we exposed human cardiac fibroblasts to 1% O <sub>2</sub> levels. In hypoxic condition we found miR-29 down-modulation responsible for the accumulation of collagens and 5mC. Overall, our data suggest that miR-29 family up-regulation might represent an endogenous mechanism aimed at ameliorating the age-dependent cardiac damage leading to hypertrophy and fibrosis

CHRONIC ELECTRICAL PACING INHIBITS GAP JUNCTION MEDIATED CELL-TO-CELL COMMUNICATION BY PROMOTING CX43-ACETYLATION

Communication among cardiomyocytes depends upon Gap Junction (GJ) protein expression and conductance. Previous studies demonstrated that electrical stimulation can induce GJ remodeling and evidences from neurons also indicate that electrical pacing modifies Lysine acetylase (HAT) and deacetylases (HDAC) activities. Aim of the present work was to establish whether electrical stimulation modulates GJ-mediated cardiac cell-cell communication by acetylation dependent mechanisms. Methods and results: Neonatal rat cardiomyocytes (NRCM; n=3) and in HL-1 atrial cells (n=20) were exposed to electrical field stimulation for 24 hours (Ionoptix C-Pace\uae; 0.5 Hz, 20 V, 0.5 msec pulses). Connexin 43 (Cx43) expression decreased almost 50% in NRCM and 40 % in HL-1; in contrast Cx40 and Cx45 expression was unchanged. Further, confocal microscopy revealed that electrical stimulation induced Cx43 accumulation in the cytoplasm of HL-1 cells. Electrical stimulation significatly down-regulated HDAC activity up to the 30% (n=3), whereas HAT activity was not modified; the net effect was a general increase of cell protein acetylation, confirmed by western blot analysis. Specifically, the pacing-dependent acetylation of Cx43 was proven by immunoprecipitation assay (n=5). Interestingly, our model mimicked the action of the HDAC pan-inhibitors TSA and SAHA on Cx43 expression and intracellular distribution, although we did not observe Cx43 mRNA significant reduction in electrically stimulated cells. In agreement, MG132 proteasome inhibitor (10 \ub5M) restored Cx43 expression level. Finally, also the treatment of paced cells with the HAT inhibitor Anacardic Acid (0.5 \ub5M) was able to rescue Cx43 level (n=4). Intriguingly, preliminary results also indicate lateralization and increased acetylation of Cx43 in the left ventricles of dogs with pacing-induced dilated cardiomyopathy (n=4). Conclusions: In vitro electrical stimulation of cardiac cells promotes Cx43 acetylation, which results in Cx43 down-modulation and intracellular relocalization, confirmed also in vivo. Our findings suggest that electrical activity-dependent increase in Cx43 acetylation might be a novel mechanism for the regulation of cardiomyocyte communication and, thus, represent a new tool for rhythm disturbance regulation

Extracellular vesicles in metabolic disease

Extracellular vesicles (EVs) are submicron-sized lipid envelopes that are produced and released from a parent cell and can be taken up by a recipient cell. EVs are capable of mediating cellular signalling by carrying nucleic acids, proteins, lipids and cellular metabolites between cells and organs. Metabolic dysfunction is associated with changes in plasma concentrations of EVs as well as alterations in their EV cargo. Since EVs can act as messengers between parent and recipient cells, they could be involved in cell-to-cell and organ-to-organ communication in metabolic diseases. Recent literature has shown that EVs are produced by cells within metabolic tissues, such as adipose tissue, pancreas, muscle and liver. These vesicles have therefore been proposed as a novel intercellular communication mode in systemic metabolic regulation. In this review, we will describe and discuss the current literature that investigates the role of adipose-derived EVs in the regulation of obesity-associated metabolic disease. We will particularly focus on the EV-dependent communication between adipocytes, the vasculature and immune cells in type 2 diabetes

Extracellular vesicles in metabolic disease

Extracellular vesicles (EVs) are submicron-sized lipid envelopes that are produced and released from a parent cell and can be taken up by a recipient cell. EVs are capable of mediating cellular signalling by carrying nucleic acids, proteins, lipids and cellular metabolites between cells and organs. Metabolic dysfunction is associated with changes in plasma concentrations of EVs as well as alterations in their EV cargo. Since EVs can act as messengers between parent and recipient cells, they could be involved in cell-to-cell and organ-to-organ communication in metabolic diseases. Recent literature has shown that EVs are produced by cells within metabolic tissues, such as adipose tissue, pancreas, muscle and liver. These vesicles have therefore been proposed as a novel intercellular communication mode in systemic metabolic regulation. In this review, we will describe and discuss the current literature that investigates the role of adipose-derived EVs in the regulation of obesity-associated metabolic disease. We will particularly focus on the EV-dependent communication between adipocytes, the vasculature and immune cells in type 2 diabetes

Extracellular vesicles in metabolic disease

Extracellular vesicles (EVs) are submicron-sized lipid envelopes that are produced and released from a parent cell and can be taken up by a recipient cell. EVs are capable of mediating cellular signalling by carrying nucleic acids, proteins, lipids and cellular metabolites between cells and organs. Metabolic dysfunction is associated with changes in plasma concentrations of EVs as well as alterations in their EV cargo. Since EVs can act as messengers between parent and recipient cells, they could be involved in cell-to-cell and organ-to-organ communication in metabolic diseases. Recent literature has shown that EVs are produced by cells within metabolic tissues, such as adipose tissue, pancreas, muscle and liver. These vesicles have therefore been proposed as a novel intercellular communication mode in systemic metabolic regulation. In this review, we will describe and discuss the current literature that investigates the role of adipose-derived EVs in the regulation of obesity-associated metabolic disease. We will particularly focus on the EV-dependent communication between adipocytes, the vasculature and immune cells in type 2 diabetes

Higher cardiogenic potential of iPSCs derived from cardiac versus skin stromal cells

Prior studies have demonstrated that founder cell type could influence induced pluripotent stem cells (iPSCs) molecular and developmental properties at early passages after establishing their pluripotent state. Herein, we evaluated the persistence of a functional memory related to the tissue of origin in iPSCs from syngeneic cardiac (CStC) vs skin stromal cells (SStCs). We found that, at passages greater than 15, iPSCs from cardiac stromal cells (C-iPSCs) produced a higher number of beating embryoid bodies than iPSCs from skin stromal cells (S-iPSCs). Flow cytometry analysis revealed that dissected beating areas from C-iPSCs exhibited more Troponin-T positive cells compared to S-iPSCs. Beating areas derived from C-iPSCs displayed higher expression of cardiac markers, more hyperpolarized diastolic potentials, larger action potential amplitude and higher contractility than beaters from skin. Also, different microRNA subsets were differentially modulated in CStCs vs SStCs during the reprogramming process, potentially accounting for the higher cardiogenic potentials of C-iPSCs vs S-iPSCs. Therefore, the present work supports the existence of a founder organ memory in iPSCs obtained from the stromal component of the origin tissue

Hepatic miR-144 Drives Fumarase Activity Preventing NRF2 Activation During Obesity

23sinoneBackground and Aims: Oxidative stress plays a key role in the development of metabolic complications associated with obesity, including insulin resistance and the most common chronic liver disease worldwide, nonalcoholic fatty liver disease. We have recently discovered that the microRNA miR-144 regulates protein levels of the master mediator of the antioxidant response, nuclear factor erythroid 2-related factor 2 (NRF2). On miR-144 silencing, the expression of NRF2 target genes was significantly upregulated, suggesting that miR-144 controls NRF2 at the level of both protein expression and activity. Here we explored a mechanism whereby hepatic miR-144 inhibited NRF2 activity upon obesity via the regulation of the tricarboxylic acid (TCA) metabolite, fumarate, a potent activator of NRF2. Methods: We performed transcriptomic analysis in liver macrophages (LMs) of obese mice and identified the immuno-responsive gene 1 (Irg1) as a target of miR-144. IRG1 catalyzes the production of a TCA derivative, itaconate, an inhibitor of succinate dehydrogenase (SDH). TCA enzyme activities and kinetics were analyzed after miR-144 silencing in obese mice and human liver organoids using single-cell activity assays in situ and molecular dynamic simulations. Results: Increased levels of miR-144 in obesity were associated with reduced expression of Irg1, which was restored on miR-144 silencing in vitro and in vivo. Furthermore, miR-144 overexpression reduces Irg1 expression and the production of itaconate in vitro. In alignment with the reduction in IRG1 levels and itaconate production, we observed an upregulation of SDH activity during obesity. Surprisingly, however, fumarate hydratase (FH) activity was also upregulated in obese livers, leading to the depletion of its substrate fumarate. miR-144 silencing selectively reduced the activities of both SDH and FH resulting in the accumulation of their related substrates succinate and fumarate. Moreover, molecular dynamics analyses revealed the potential role of itaconate as a competitive inhibitor of not only SDH but also FH. Combined, these results demonstrate that silencing of miR-144 inhibits the activity of NRF2 through decreased fumarate production in obesity. Conclusions: Herein we unravel a novel mechanism whereby miR-144 inhibits NRF2 activity through the consumption of fumarate by activation of FH. Our study demonstrates that hepatic miR-144 triggers a hyperactive FH in the TCA cycle leading to an impaired antioxidant response in obesity.noneAzzimato V.; Chen P.; Barreby E.; Morgantini C.; Levi L.; Vankova A.; Jager J.; Sulen A.; Diotallevi M.; Shen J.X.; Miller A.; Ellis E.; Ryden M.; Naslund E.; Thorell A.; Lauschke V.M.; Channon K.M.; Crabtree M.J.; Haschemi A.; Craige S.M.; Mori M.; Spallotta F.; Aouadi M.Azzimato, V.; Chen, P.; Barreby, E.; Morgantini, C.; Levi, L.; Vankova, A.; Jager, J.; Sulen, A.; Diotallevi, M.; Shen, J. X.; Miller, A.; Ellis, E.; Ryden, M.; Naslund, E.; Thorell, A.; Lauschke, V. M.; Channon, K. M.; Crabtree, M. J.; Haschemi, A.; Craige, S. M.; Mori, M.; Spallotta, F.; Aouadi, M