Hypoxia-induced Myocardial Cell Research Articles

CircUBAP2 ameliorates hypoxia-induced acute myocardial injury by competing with miR-148b-3p and mediating CDKN1B expression

BackgroundA recent high-throughput sequencing study revealed an anomalous underexpression of circular RNA UBAP2 (circUBAP2) in acute myocardial infarction (AMI), yet its biological function within this context remains elusive. This study aims to unravel whether circUBAP2 is instrumental in modulating the pathogenesis of AMI and to illuminate the underlying molecular mechanisms at play. ResultscircUBAP2 was abnormally low expressed in AMI. Inducing circUBAP2 ameliorated hypoxia-induced myocardial cell injury by enhancing cellular viability, and decreasing lactate dehydrogenase release, apoptosis, inflammation, and oxidative damage. circUBAP2 targeted miR-148b-3p, miR-148b-3p overexpression offset circUBAP2-induced cardioprotection. Cyclin-dependent kinase inhibitor 1B (CDKN1B) was mediated by miR-148b-3p, and CDKN1B upregulation suppressed the deleterious effect of circUBAP2 silencing on hypoxic AC16 cells. In addition, overexpression of circUBAP2 improved myocardial injury, decreased myocardial cell apoptosis, and alleviated inflammation and oxidative stress in AMI mice. ConclusionscircUBAP2 ameliorates AMI by competitively binding to miR-148b-3p and mediating CDKN1B expression.How to cite: Li F, Xu L, Ou J, et al. circUBAP2 ameliorates hypoxia-induced acute myocardial injury by competing with miR-148b-3p and mediating CDKN1B expression. Electron J Biotechnol 2024;68. https://doi.org/10.1016/j.ejbt.2023.11.003.

Potentilla reptans L. preconditioning regulates H19 and MIAT long noncoding RNAs in H9C2 myoblasts Ischemia/Reperfusion model

The present study aimed to evaluate the effect of the ethyl acetate fraction of P. reptans root (PEF) preconditioning on expressions of lncRNAs H19 and MIAT in H9C2 myoblasts I/R injury.H9C2 cells were treated with different concentrations ranging from (10–400 µg/ml) of PEF for 24 h, followed by simulation of I/R condition. For I/R experiments, H9C2 cells were subjected with the oxygen and glucose deprivation for 2 h.H9C2 cell viability was significantly enhanced by PEF preconditioning under I/R condition in a concentration-dependent manner up to 200 µg/ml as a EC50. The PEF significantly diminished the expression of lncRNA MIAT and rate of apoptosis against the I/R group. In addition, PEF pretreated before stimulation I/R condition increased H19 expression compared to the normal PEF group with no statistically significant differences between groups. Hence, the results suggest that PEF can protect cardiomyocytes during hypoxia-induced myocardial cell injury by targeting specific involved genes.

Albumin nanoparticles equipped with miR-24 agonist mediate transforming growth factor (TGF)-β signaling pathway to inhibit hypoxia-induced myocardial cell apoptosis

Abnormal expression of miR-24 is related to cardiomyocyte apoptosis. This study mainly explored the role of miR-24 in cardiomyocyte apoptosis and its possible mechanism. Cardiomyocytes were obtained from newborn SD mice and were randomly separated into blank group, hypoxia group (hypoxia), miR-24 group (hypoxia+miR-24 agonist nano albumin particles), and pathway agonist (hypoxia+miR-24 agonist nano albumin particles+TGF-β signaling pathway inhibitor) group. miR-24 level in hypoxia group and pathway agonist group was sharply decreased when compared to that of the blank or miR-24 group (P < 0.05). Cell survival rate and apoptosis of hypoxia group and pathway agonist were also significantly inhibited when compared to that of blank or miR-24 group (P < 0.05). The expression levels of TGF-β, Smad, p-Smad, caspsase-3, Bcl-2, and HIF-1a were sharply up-regulated in hypoxia group and pathway agonists group, compared to blank group and miR-24 group (P < 0.05). miR-24 can inhibit cardiomyocyte apoptosis through interaction with TGF-β signaling pathway factors, to up-regulate the TGF-β pathway factor expression and activate TGF-β signaling. TGF-β also interacts with downstream factor Smad to activate the Smad pathway and phosphorylate Smad, thereby activating the activity of HIF-1a, up-regulating HIF-1a, and inhibiting the expression of apoptotic proteins caspsase-3 and Bcl-2.

LncRNA XIST facilitates hypoxia-induced myocardial cell injury through targeting miR-191-5p/TRAF3 axis.

Myocardial infarction is one of the most lethal diseases in cardiovascular diseases. In the present work, we aimed to elucidate the molecular and functional association long non-coding RNA (lncRNA) X-inactive specific transcript (XIST), microRNA (miR)-191-5p, and TNF receptor-associated factor 3 (TRAF3). Human cardiomyocyte primary cells (HCMs) were stimulated by hypoxia to establish a model of myocardial injury in vitro. The relative expressions of XIST, miR-191-5p, and TRAF3 were measured using quantitative real-time polymerase chain reaction (qRT-PCR) assay. The capabilities of proliferation and apoptosis were determined using cell counting kit (CCK-8) and flow cytometry assays, respectively. The molecular interactions were verified using dual luciferase assay. The protein contents of TRAF3, Bcl-2, and Bax were calculated using western blot assay. XIST was significantly increased, but miR-191-5p was reduced in hypoxia-treated HCMs compared to that in control group. Either downregulated XIST or enforced miR-191-5p markedly enhanced cell viability and restrained cell apoptotic rate in hypoxia-treated HCMs. Mechanistically, XIST directly interacted with miR-191-5p to competitive releasing TRAF3 expression. Importantly, overexpression of TRAF3 dramatically diminished the protective effects of XIST knockdown on hypoxia-triggered HCMs injury. Collectively, our data elucidated a novel "lncRNA XIST/miR-191-5p/TRAF3" molecular network in vitro, indicating that the reduced lncRNA XIST-protected HCMs from hypoxia-induced cell injury by regulating miR-191-5p/TRAF3 signaling, which might provide some convincing evidences for further understanding the influences of "lncRNA-miRNA-mRNA" network in the development of MI.

ZNF561-AS1 Regulates Cell Proliferation and Apoptosis in Myocardial Infarction Through miR-223-3p/NLRP3 Axis

Long non-coding RNAs (lncRNAs) have been widely recognized as important regulators in myocardial infarction (MI) and other heart diseases. Our study aimed to investigate the mechanism and biological function of an unknown lncRNA zinc finger protein 561 antisense RNA 1 (ZNF561-AS1) in MI. After confirming the MI model was successful, we applied reverse transcription quantitative polymerase chain reaction and Western blot (WB) and found that the expression of NLR family pyrin domain containing 3 (NLRP3), interleukin (IL)-1β, and IL-18 was substantially increased in infarct and border zones of MI mice heart at 24 h and 72 h compared with that in sham-operated models. Moreover, we found that NLRP3 expression was promoted in hypoxia human cardiomyocytes (HCMs). Through cell function assays including CCK-8, 5-Ethynyl-2’-deoxyuridine (EdU), flow cytometry, and TdT-mediated dUTP Nick-End Labeling (TUNEL), supported by WB analysis, we verified that silencing of NLRP3 facilitated proliferation but impeded apoptosis of hypoxia-induced myocardial cell. Moreover, Ago2-RIP and RNA pull-down assays displayed that NLRP3 could combine with miR-223-3p. Luciferase reporter assays further confirmed that NLRP3 was directly targeted by miR-223-3p. Simultaneously, we found that miR-223-3p was the downstream gene of ZNF561-AS1. In addition, we conducted a series of rescue experiments to affirm that ZNF561-AS1 regulated cell proliferation and apoptosis in MI through miR-223-3p/NLRP3 axis.

Retraction: Knockdown of TUG1 aggravates hypoxia-induced myocardial cell injury via regulation of miR-144-3p/Notch1.

Retraction of ‘Knockdown of TUG1 aggravates hypoxia-induced myocardial cell injury via regulation of miR-144-3p/Notch1’ by Bo Zhu et al., RSC Adv., 2019, 9, 22931–22941, DOI: 10.1039/C9RA01311C.

Suppression of microRNA-101 attenuates hypoxia-induced myocardial H9c2 cell injury by targeting DIMT1-Sp1/survivin pathway.

The article "Suppression of microRNA-101 attenuates hypoxia-induced myocardial H9c2 cell injury by targeting DIMT1-Sp1/survivin pathway, by Z.-X. Guo, F.-Z. Zhou, W. Song, L.-L. Yu, W.-J. Yan, L.-H. Yin, H. Sang, H.-Y. Zhang, published in Eur Rev Med Pharmacol Sci 2018; 22 (20): 6965-6976-DOI: 10.26355/eurrev_201810_16167-PMID: 30402863" has been withdrawn from the authors due to some inaccuracies. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/16167.

LncRNA TUG1 Contributes to Hypoxia-Induced Myocardial Cell Injury Through Downregulating miR-29a-3p in AC16 Cells.

Myocardial ischemia is a common reason that causes human death globally. Long noncoding RNA taurine upregulated 1 (TUG1) serves as an oncogene in a variety of cancers. In this article, we aimed to investigate the role of TUG1 and its underlying signal pathway in hypoxia-induced myocardial cell injury. Cell viability, apoptosis, and lactate dehydrogenase (LDH) release were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, flow cytometry, western blot assay, and LDH cytotoxicity assay. Quantitative real-time polymerase chain reaction was applied to measure the enrichment of TUG1 and miR-29a-3p. MiR-29a-3p was predicted as a target of TUG1 by StarBase bioinformatic software, and the target relationship between TUG1 and miR-29a-3p was verified by dual-luciferase reporter assay. Hypoxia treatment induced the apoptosis and LDH release while inhibited the viability of AC16 cells. TUG1 was markedly upregulated while the level of miR-29a-3p was notably decreased in hypoxia-stimulated AC16 cells. TUG1 contributed to hypoxia-induced AC16 injury. MiR-29a-3p depletion intensified hypoxia-induced AC16 damage. TUG1 negatively regulated the expression of miR-29a-3p through their direct interaction in AC16 cells. TUG1 silencing-mediated influences in hypoxia-induced AC16 cells were partly reversed by the interference of miR-29a-3p. In conclusion, TUG1 accelerated hypoxia-induced AC16 injury through inversely modulating the level of miR-29a-3p. TUG1/miR-29a-3p axis might be an underlying therapeutic target for myocardial ischemia.

Long non-coding RNA MALAT1 regulates cardiomyocytes apoptosis after hypoxia/reperfusion injury via modulating miR-200a-3p/PDCD4 axis

Long non-coding RNAs (lncRNAs) have been reported to be crucial modulators in various heart diseases, including myocardial infarction (MI). LncRNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) has been reported to be highly expressed in MI samples. However, the mechanism and biological function of MALAT1 in myocardial infarction are still marked. Similarly, programmed cell death 4 (PDCD4) was also upregulated in MI samples. Therefore, MALAT1 and PDCD4 were chosen to do further study. At first, qRT-PCR was applied to examine the expression patterns of MALAT1 and PDCD4. The results showed that both MALAT1 and PDCD4 were upregulated in MI mice model and the hypoxia-induced myocardial cell. Subsequently, loss-of function assays were conducted to examine the impacts of MALAT1 or PDCD4 on cellular processes. Results of MTT assay and flow cytometry analyses manifested that knockdown of MALAT1 or PDCD4 enhanced cell viability, promoted cell cycle progress and suppressed cell apoptosis. Transferase-mediated dUTP nick end labeling (TUNEL) assay revealed that MALAT1 knockdown or PDCD4 knockdown decreased cell apoptosis in MI mice model. Subsequently, mechanism experiments revealed that microRNA-200a-3p (miR-200a-3p) could bind to either MALATA1 or PDCD4. Combining with the cytoplasmic location of MALAT1, we confirmed that MALAT1 acted as a competing endogenous RNA (ceRNA) to upregulate PDCD4 by sponging miR-200a-3p. Finally, rescue assay suggested that MALAT1-miR-200a-3p-PDCD4 axis regulated the proliferation, cell cycle progression and apoptosis of hypoxia-induced myocardial cells.

Retracted Article: Knockdown of TUG1 aggravates hypoxia-induced myocardial cell injury via regulation of miR-144-3p/Notch1

Myocardial infarction is a common cause of mortality in cardiovascular diseases. Long noncoding RNA taurine-upregulated gene 1 (TUG1) has been reported to play an important role in the regulation of myocardial injury; however, the mechanism via which TUG1 participates in myocardial infarction is unknown. In this study, hypoxia-treated cardiomyoblast H9c2 cells were used as a model of myocardial infarction. Cell transfection was conducted using Lipofectamine 2000 for 48 h. Hypoxia-induced injury was investigated by cell viability and apoptosis using the trypan blue exclusion method, flow cytometry and Western blot. The expressions of TUG1, microRNA-144-3p (miR-144-3p) and the Notch1 pathway were investigated by a quantitative real-time polymerase chain reaction and Western blot. The association between miR-144-3p and TUG1 or Notch1 was analyzed by bioinformatics analysis and luciferase reporter assay. Our results showed that hypoxia-induced H9c2 cell injury led to the inhibition of cell viability and promotion of apoptosis. Moreover, hypoxia could cause the up-regulation of TUG1 and Notch1 expression and down-regulation of miR-144-3p. The knockdown of TUG1 or overexpression of miR-144-3p aggravated the hypoxia-induced viability suppression and apoptosis production in the H9c2 cells. Moreover, miR-144-3p was indicated to be bound to TUG1, and its abrogation reversed the silencing of TUG1-mediated promotion of hypoxia-induced injury. In addition, Notch1 was a target of miR-144-3p, and its restoration attenuated the miR-144-3p-mediated promotion of hypoxia-induced injury. Moreover, TUG1 interference alleviated the hypoxia-induced activation of the Notch1/Hes-1 pathway via the regulation of miR-144-3p. In conclusion, the interference of TUG1 contributed to hypoxia-induced injury via the regulation of the miR-144-3p/Notch1/Hes-1 pathway; this indicated a novel mechanism for understanding the pathogenesis of myocardial infarction.

Suppression of microRNA-101 attenuates hypoxia-induced myocardial H9c2 cell injury by targeting DIMT1-Sp1/survivin pathway.

MicroRNAs (miRNAs) are small single-stranded RNAs in eukaryotic cells, which play important regulatory roles in the pathogenesis of various diseases. We aimed to investigate the effects of miRNA-101 (miR-101) on hypoxia-induced myocardial infarction (MI) cell injury model (myocardial H9c2 cell injury model). The possible target gene of miR-101 was also analyzed. H9c2 cells were exposed to hypoxia treatment. Cell viability, migration, invasion, apoptosis and the expression of miR-101 were detected using CCK-8 assay, transwell assay, flow cytometer analysis, Western blotting and qRT-PCR, respectively. Then, the effects of miR-101 overexpression or suppression on the cell injury induced by hypoxia were assessed. Dual luciferase reporter assay was used to analyze the possible target gene of miR-101. Finally, the effects of dimethyladenosine transferase 1 homolog (DIMT1), the possible target gene of miR-101, on H9c2 cell injury were investigated. Hypoxia significantly induced H9c2 cell injury. miR-101 was up-regulated after hypoxia induction. Hypoxia-induced cell injury was significantly reversed by miR-101 suppression and exacerbated by miR-101 overexpression. DIMT1 was a direct target gene of miR-101. Knockdown of DIMT1 markedly inhibited the protective effects of miR-101 suppression on hypoxia-induced cell injury by suppressing specific protein 1 (Sp1)/Survivin pathway. We verified the critical roles of miR-101 in regulating myocardial cell injury induced by hypoxia. DIMT1-mediated the Sp1/Survivin pathway was also involved in this process. Our findings replenished the understanding of the regulatory roles of miRNAs in hypoxia-induced MI cell injury and provided new molecular target for therapy and diagnosis of MI.

Polydatin protects against acute myocardial infarction-induced cardiac damage by activation of Nrf2/HO-1 signaling.

Polydatin is a traditional Chinese medicine that provides myocardial protection after acute myocardial infarction (AMI). The study aim was to investigate the myocardial protection polydatin in H9c2 myocardial cells cultured in a hypoxic atmosphere and in a rat AMI model induced by ligating the left anterior descending coronary artery and treated with polydatin 100mg/kg/day for 30days. The involvement of Nrf2 in mediating the effects of polydatin was investigated in H9c2 cells following Nrf2 knockdown by transfection of siRNA. Polydatin suppressed hypoxia-induced H9c2 cell apoptosis and reactive oxygen species (ROS) generation by promoting Nrf2/HO-1 signaling. Nrf2 knockdown reversed the protective effects of polydatin against hypoxia-induced myocardial cell injury. The in vivo results were consistent with polydatin suppression of apoptosis and ROS generation in myocardial tissue by promotion of Nrf2/HO-1 signaling. In conclusion, polydatin effectively inhibited hypoxia- and AMI-induced myocardial damage by promotion of Nrf2/HO-1 signaling.

LncRNA TUG1 serves an important role in hypoxia-induced myocardial cell injury by regulating the miR‑145‑5p‑Binp3 axis.

The aim of the present study was to investigate the function of long non-coding RNA TUG1 in hypoxia-induced myocardial cell injury and to explore the potential molecular mechanisms. The cardiomyocyte cell line H9c2 was cultured under hypoxic and normoxic conditions. TUG1 expression under hypoxic conditions was then detected. The effects of TUG1 overexpression on viability, apoptosis, migration and invasion were assayed. In addition, the microRNA (miR)-145-5p expression was detected. Following H9c2 cell transfection with miR-145-5p mimics, the H9c2 cell viability, apoptosis, migration and invasion were also detected. Additionally, the target gene of miR-145-5p was assayed by Luciferase reporter assay. The protein expressions of Wnt-3a, Wnt5a, and β-catenin in H9c2 cells under hypoxic conditions were also determined. The results revealed that hypoxia induced injury in H9c2 cells, including inhibiting cell viability, migration and invasion, and promoting cell apoptosis. Overexpression of TUG1 aggravated hypoxia-induced injury in H9c2 cells. In addition, miR-145-5p was negatively regulated by TUG1, and TUG1 overexpression aggravated hypoxia-induced injury via the downregulation of miR-145-5p. Furthermore, B-cell lymphoma 2 interacting protein 3 (Bnip3) was a target of miR-145-5p, and overexpression of Bnip3 aggravated hypoxia-induced cell injury by activating Wnt/β-catenin signaling pathways in H9c2 cells. In conclusion, overexpression of TUG1 aggravated hypoxia-induced injury in cardiomyocytes by regulating the miR-145-5p-Binp3 axis. Activation of the Wnt/β-catenin signaling pathway may be a key mechanism to mediate the role of TUG1 in regulating hypoxia-induced myocardial injury. TUG1 may be an effective diagnostic marker and therapeutic target for myocardial ischemia.

Long Non-Coding RNA H19 Protects H9c2 Cells against Hypoxia-Induced Injury by Targeting MicroRNA-139

Acute myocardial infarction (AMI) occurs when blood supply to the heart is diminished (ischemia) for long time; ischemia is primarily caused due to hypoxia. The present study evaluated the effects of long non-coding RNA H19 on hypoxic rat H9c2 cells and mouse HL-1 cells. Hypoxic injury was confirmed by measuring cell viability, migration and invasion, and apoptosis using MTT, Transwell and flow cytometry assays, respectively. H19 expression after hypoxia was estimated by qRT-PCR. We then measured the effects of non-physiologically expressed H19, knockdown of miR-139 with or without H19 silence, and abnormally expressed Sox8 on hypoxia-induced H9c2 cells. Moreover, the interacted miRNA for H19 and downstream target gene were virtually screened and verified. The involved signaling pathways and the effects of abnormally expressed H19 on contractility of HL-1 cells were explored via Western blot analysis. Hypoxia induced decreases of cell viability, migration and invasion, increase of cell apoptosis and up-regulation of H19. Knockdown of H19 increased hypoxia-induced injury in H9c2 cells. H19 acted as a sponge for miR-139 and H19 knockdown aggravated hypoxia-induced injury by up-regulating miR-139. Sox8 was identified as a target of miR-139, and its expression was negatively regulated by miR-139. The mechanistic studies revealed that overexpression of Sox8 might decrease hypoxia-induced cell injury by activating the PI3K/AKT/mTOR pathway and MAPK. Besides, H19 promoted contractility of HL-1 cells. These findings suggest that H19 alleviates hypoxia-induced myocardial cell injury by miR-139-mediated up-regulation of Sox8, along with activation of the PI3K/AKT/mTOR pathway and MAPK.

Tetramethylpyrazine Ameliorated Hypoxia-Induced Myocardial Cell Apoptosis via HIF-1α/JNK/p38 and IGFBP3/BNIP3 Inhibition to Upregulate PI3K/Akt Survival Signaling

Background: Hemorrhagic shock (HS) is the major cause of death from trauma. Hemorrhagic shock may lead to cellular hypoxia and organ damage. Our previous findings showed that HS induced a cardiac apoptosis pathway and synergistically caused myocardial cell damage in diabetic rats under trauma-induced HS. Tetramethylpyrazine (TMP) is a major biologically active ingredient purified from the rhizome of Ligusticum wallichii (called Chuang Xiong in Chinese). Chuan Xiong rescued cells from synergistic cardiomyoblast cell injury under high-glucose (HG) conditions plus hypoxia. TMP is one of the most important active ingredients that elevated the survival rate in ischemic brain injury and prevented inducible NO synthase expression to have anti-inflammatory effects against cell damage in different cell types. Method: Here, we further investigate whether TMP can protect against hypoxic (<1% oxygen) conditions in H9c2 cardiomyoblast cells for 24 hrs. Results: Our results showed that hypoxia mediated through HIF-1α/JNK/p38 activation significantly elevated the levels of the hypoxia-related proteins HIF-1α, BNIP3 and IGFBP3, further enhanced the pro-apoptotic protein Bak and upregulated downstream Caspase 9 and 3, resulting in cell death. All of these phenomena were fully recovered under TMP treatment. We observed that TMP exerted this effect by activating the IGF1 receptor survival pathway, dependent primarily on PI3K/Akt. When PI3K (class I) was blocked by specific siRNA, the hypoxia-induced activated caspase 3 and cell apoptosis could not be reversed by TMP treatment. Conclusion: Our results strongly suggest that TMP could be used to restore hypoxia-induced myocardial cell apoptosis and cardiac hypoxic damage.

RhoA/ROCK pathway regulates hypoxia-induced myocardial cell apoptosis.

To observe the regulatory effects of RhoA/ROCK pathway on the apoptosis of cardiac myocyte induced by anoxia and its mechanism. The model of cardiac myocyte anoxia was established. The beat pulsations and apoptosis rates after 1 h, 3 h, 6 h, 9 h and 12 h of anoxia were recorded and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspae-3 were detected, too. The apoptosis and the expressions of related proteins were detected after RNAi of RhoA and the inhibition of ROCK by Y-27632. The beat pulsations after 1 h, 3 h, 6 h, 9 h and 12 h decreased gradually but the apoptosis rates increased gradually, and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspase-3 were increasing along with the increasing duration of anoxia. The apoptotic rates after 1 h, 3 h, 6 h, 9 h and 12 h of anoxia were (4.360.98)%, (8.362.12)%, (15.323.62)%, (18.684.83)% and (24.566.22)%, respectively and decreased more significantly than control group in different time points of anoxia (P<0.05), and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspase-3 decreased significantly (P<0.05). The apoptosis rate and the expressions of RhoA, ROCK1/2, p-PI3K, p-AKT and caspase-3 decreased significantly (P<0.05) after the inhibition of ROCK by Y-27632 (P<0.05). RhoA/ROCK pathway plays a critical role in the regulation of the apoptosis of cardiac myocyte induced by anoxia, which may be accompanied by regulating the activity of PI3K/AKT/Caspase-3 pathway.

P10 miRNA-30 family inhibition protects against cardiac ischemic injury by regulating cystathionine-gamma-lyase expression

Background Myocardial infarction (MI) is a leading cause of death globally. MicroRNAs (miRs) have been identified as a novel class of MI injury regulators. Hydrogen sulfide (H2S) is a gaseous signaling molecule that regulates cardiovascular function. The purpose of this study was to explore the role of the miR-30 family in protecting against MI injury by regulating H2S production. Methods and Results Two days after coronary artery ligations in rats, the expression of miR-30 family was significantly upregulated in the non-infarct and border zone regions. However, the CSE expression was just the opposite. The overexpression of each miR-30 family member decreased mRNA and protein levels of CSE and reduced H2S production. In contrast, silencing the whole miR-30 family resulted in elevated CSE expression and increased H2S production. Forced expression of the miR-30 family aggravated hypoxia-induced myocardial cell injury. This was reversed by locked nucleic acid (LNA)-miR-30 family inhibitor transfection. Systemic delivery of a LNA-miR-30 family inhibitor correspondingly repressed the miR-30 family in mouse cardiac tissue and increased CSE expression and H2S production. The therapeutic targeting of the miR-30 family in mice reduced infarct size, decreased apoptotic cell number in the peri-infarct region, and improved cardiac function in response to MI, whereas miR-30b overexpression by lentivirus in vivo exacerbated MI injury. Conclusion The inhibition of miR-30 family expression in the heart can protect against mouse cardiac ischemic injury by increasing CSE expression and H2S production, indicating the therapeutic potential of miR-30 for cardiac diseases associated with MI injury.

Tanshinone IIA and Cryptotanshinone Prevent Mitochondrial Dysfunction in Hypoxia-Induced H9c2 Cells: Association to Mitochondrial ROS, Intracellular Nitric Oxide, and Calcium Levels

The protective actions of tanshinones on hypoxia-induced cell damages have been reported, although the mechanisms have not been fully elucidated. Given the importance of nitric oxide (NO) and reactive oxygen species (ROS) in regulation of cell functions, the present study investigated the effects of two major tanshinones, Tanshinone IIA (TIIA) and cryptotanshinone (CT), on hypoxia-induced myocardial cell injury and its relationships with intracellular NO and ROS, calcium, and ATP levels in H9c2 cells. Chronic hypoxia significantly reduced cell viability which accompanied with LDH release, increase in mitochondrial ROS, intracellular NO and calcium levels, decrease in superoxide dismutase (SOD) activity, and cellular ATP contents. TIIA and CT significantly prevented cell injury by increasing cell viability and decreasing LDH release. The protective effects of tanshinones were associated with reduced mitochondrial superoxide production and enhanced mitochondrial SOD activity. Tanshinones significantly reduced intracellular NO and Ca2+ levels. ATP levels were also restored by TIIA. These findings suggest that the cytoprotective actions of tanshinones may involve regulation of intracellular NO, Ca2+, ATP productions, mitochondrial superoxide production, and SOD activity, which contribute to their actions against hypoxia injuries.

Protein kinase C activation aggravates hypoxic myocardial injury by stimulating Na +/H + exchange

The physiological and pathophysiological roles of protein kinase C activation were investigated in cultured mouse myocardial cells. First, effects of 12-O-tetra-decanoyl-phorbol-13-acetate (TPA), a potent activator of protein kinase C, on the intracellular pH (pHi) and cytosolic free Ca2+ level [( Ca2+]i) were studied, using 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) and quin-2, respectively. In the presence of the Ca ionophore A23187, TPA induced a rise in pHi by activating amiloride-sensitive Na+/H+ exchange and also produced a rise in [Ca2+]i above that seen with A23187 alone. These effects were totally inhibited by amiloride. Second, the effect of TPA on hypoxia-induced myocardial cell injury was evaluated. The addition of TPA to the culture medium enhanced creatine kinase release from hypoxic myocardial cells (95% N2 + 5% CO2). This effect was markedly suppressed by the addition of amiloride. These data suggests that protein kinase C activation aggravates hypoxic myocardial injury, presumably by inducing Ca2+ overload. This event is secondary to activation of Na+/Ca2+ exchange through accelerated influx of Na+ into the cells as a result of Na+/H+ exchange stimulation by protein kinase C.