KAT8-mediated H4K16ac is essential for sustaining trophoblast self-renewal and proliferation via regulating CDX2.

Abnormal trophoblast self-renewal and differentiation during early gestation is the major cause of miscarriage, yet the underlying regulatory mechanisms remain elusive. Here, we show that trophoblast specific deletion of Kat8, a MYST family histone acetyltransferase, leads to extraembryonic ectoderm abnormalities and embryonic lethality. Employing RNA-seq and CUT&Tag analyses on trophoblast stem cells (TSCs), we further discover that KAT8 regulates the transcriptional activation of the trophoblast stemness marker, CDX2, via acetylating H4K16. Remarkably, CDX2 overexpression partially rescues the defects arising from Kat8 knockout. Moreover, increasing H4K16ac via using deacetylase SIRT1 inhibitor, EX527, restores CDX2 levels and promoted placental development. Clinical analysis shows reduced KAT8, CDX2 and H4K16ac expression are associated with recurrent pregnancy loss (RPL). Trophoblast organoids derived from these patients exhibit impaired TSC self-renewal and growth, which are significantly ameliorated with EX527 treatment. These findings suggest the therapeutic potential of targeting the KAT8-H4K16ac-CDX2 axis for mitigating RPL, shedding light on early gestational abnormalities.

Unraveling the role of LDHA and VEGFA in oxidative stress: A pathway to therapeutic interventions in cerebral aneurysms.

Cerebral aneurysms (CA) are critical conditions often associated with oxidative stress in vascular endothelial cells (VECs). The enzyme lactate dehydrogenase A (LDHA) plays a crucial role in glycolysis and lactate metabolism, processes implicated in the pathogenesis of aneurysms. Understanding these molecular mechanisms can inform the development of novel therapeutic targets. This study investigated the role of lactate metabolism and lactate-related genes, particularly LDHA and vascular endothelial growth factor A (VEGFA) genes, in VECs during oxidative stress. Using the GSE26969 dataset, we identified differential expression of lactate-related genes and performed functional enrichment analysis, revealing significant associations with glycolysis and lactate metabolic pathways. To induce oxidative stress, VECs were treated with H2O2, and the expression of LDHA and VEGFA was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting (WB) assays. Under oxygen-glucose deprivation/reperfusion (OGD/R) conditions, the effects of LDHA overexpression and VEGFA knockdown on cell viability and apoptosis were evaluated. Immunoprecipitation combined with western blotting was used to detect the lactylation status of LDHA following OGD/R stimulation and treatment with lactic acid (LA) and 2-deoxyglucose (2-DG). Our results indicated that oxidative stress modulates LDHA expression, glucose uptake, and lactate production, suggesting a metabolic shift towards glycolysis. LDHA overexpression improved cell survival and reduced apoptosis, while VEGFA knockdown had the opposite effect. Additionally, 2-DG treatment reduced LDHA lactylation and apoptosis. Our findings demonstrated that LDHA plays a critical role in the oxidative stress response of VECs, highlighting the potential therapeutic value of targeting glycolysis in CA. This study contributes to the understanding of metabolic adaptations in vascular pathologies and suggests new avenues for therapeutic intervention in CA management.

LncRNA DCRT Protects Against Dilated Cardiomyopathy by Preventing NDUFS2 Alternative Splicing by Binding to PTBP1.

BACKGROUND: Dilated cardiomyopathy is characterized by left ventricular dilation and continuous systolic dysfunction. Mitochondrial impairment is critical in dilated cardiomyopathy; however, the underlying mechanisms remain unclear. Here, we explored the cardioprotective role of a heart-enriched long noncoding RNA, the dilated cardiomyopathy repressive transcript (DCRT), in maintaining mitochondrial function. METHODS: The DCRT knockout (DCRT-/-) mice and DCRT knockout cells were developed using CRISPR-Cas9 technology. Cardiac-specific DCRT transgenic mice were generated using α-myosin heavy chain promoter. Chromatin coimmunoprecipitation, RNA immunoprecipitation, Western blot, and isoform sequencing were performed to investigate the underlying mechanisms. RESULTS: We found that the long noncoding RNA DCRT was highly enriched in the normal heart tissues and that its expression was significantly downregulated in the myocardium of patients with dilated cardiomyopathy. DCRT-/- mice spontaneously developed cardiac dysfunction and enlargement with mitochondrial impairment. DCRT transgene or overexpression with the recombinant adeno-associated virus system in mice attenuated cardiac dysfunction induced by transverse aortic constriction treatment. Mechanistically, DCRT inhibited the third exon skipping of NDUFS2 (NADH dehydrogenase ubiquinone iron-sulfur protein 2) by directly binding to PTBP1 (polypyrimidine tract binding protein 1) in the nucleus of cardiomyocytes. Skipping of the third exon of NDUFS2 induced mitochondrial dysfunction by competitively inhibiting mitochondrial complex I activity and binding to PRDX5 (peroxiredoxin 5) and suppressing its antioxidant activity. Furthermore, coenzyme Q10 partially alleviated mitochondrial dysfunction in cardiomyocytes caused by DCRT reduction. CONCLUSIONS: Our study revealed that the loss of DCRT contributed to PTBP1-mediated exon skipping of NDUFS2, thereby inducing cardiac mitochondrial dysfunction during dilated cardiomyopathy development, which could be partially treated with coenzyme Q10 supplementation.

Fibroblast-localized lncRNA CFIRL promotes cardiac fibrosis and dysfunction in dilated cardiomyopathy.

CFIRL is a long noncoding RNA (lncRNA), we previously identified as the most significantly upregulated lncRNA in the failing hearts of patients with dilated cardiomyopathy (DCM). In this study, we determined the function of CFIRL and its role in DCM. Real-time polymerase chain reaction and in situ hybridization assays revealed that CFIRL was primarily localized in the nucleus of cardiac fibroblasts and robustly increased in failing hearts. Global knockdown or fibroblast-specific knockout of CFIRL attenuated transverse aortic constriction (TAC)-induced cardiac dysfunction and fibrosis in vivo. Overexpression of CFIRL in vitro promoted fibroblast proliferation and aggravated angiotensin II-induced differentiation to myofibroblasts. CFIRL knockdown attenuated these effects. Mechanistically, RNA pull-down assay and gene expression profiling revealed that CFIRL recruited ENO1, a newly identified noncanonical transcriptional factor, to activate IL-6 transcription. IL-6 exerted a paracrine effect on cardiomyocytes to promote cardiac hypertrophy, which can be prevented by CFIRL knockdown. These findings uncover the critical role of CFIRL, a fibroblast-associated lncRNA, in heart failure by facilitating crosstalk between fibroblasts and cardiomyocytes. CFIRL knockdown might be a potent strategy to prevent cardiac remodeling in heart failure, particularly in DCM.

LncRNA CHKB-DT Downregulation Enhances Dilated Cardiomyopathy Through ALDH2.

BACKGROUND: Human cardiac long noncoding RNA (lncRNA) profiles in patients with dilated cardiomyopathy (DCM) were previously analyzed, and the long noncoding RNA CHKB (choline kinase beta) divergent transcript (CHKB-DT) levels were found to be mostly downregulated in the heart. In this study, the function of CHKB-DT in DCM was determined. METHODS: Long noncoding RNA expression levels in the human heart tissues were measured via quantitative reverse transcription-polymerase chain reaction and in situ hybridization assays. A CHKB-DT heterozygous or homozygous knockout mouse model was generated using the clustered regularly interspaced palindromic repeat (CRISPR)/CRISPR-associated protein 9 system, and the adeno-associated virus with a cardiac-specific promoter was used to deliver the RNA in vivo. Sarcomere shortening was performed to assess the primary cardiomyocyte contractility. The Seahorse XF cell mitochondrial stress test was performed to determine the energy metabolism and ATP production. Furthermore, the underlying mechanisms were explored using quantitative proteomics, ribosome profiling, RNA antisense purification assays, mass spectrometry, RNA pull-down, luciferase assay, RNA-fluorescence in situ hybridization, and Western blotting. RESULTS: CHKB-DT levels were remarkably decreased in patients with DCM and mice with transverse aortic constriction-induced heart failure. Heterozygous knockout of CHKB-DT in cardiomyocytes caused cardiac dilation and dysfunction and reduced the contractility of primary cardiomyocytes. Moreover, CHKB-DT heterozygous knockout impaired mitochondrial function and decreased ATP production as well as cardiac energy metabolism. Mechanistically, ALDH2 (aldehyde dehydrogenase 2) was a direct target of CHKB-DT. CHKB-DT physically interacted with the mRNA of ALDH2 and fused in sarcoma (FUS) through the GGUG motif. CHKB-DT knockdown aggravated ALDH2 mRNA degradation and 4-HNE (4-hydroxy-2-nonenal) production, whereas overexpression of CHKB-DT reversed these molecular changes. Furthermore, restoring ALDH2 expression in CHKB-DT+/- mice alleviated cardiac dilation and dysfunction. CONCLUSIONS: CHKB-DT is significantly downregulated in DCM. CHKB-DT acts as an energy metabolism-associated long noncoding RNA and represents a promising therapeutic target against DCM.

A Comparison of Colour Doppler Ultrasound and 2D Ultrasound as Promising Prediction Methods for the Treatment effect of Patients with Advanced Cervical Cancer.

BACKGROUND: A number of studies have evaluated the effect of colour Doppler ultrasound in patients with cervical cancer. OBJECTIVE: This study aims to evaluate the efficacy of colour Doppler ultrasound and two-dimensional ultrasound of monitoring patients with cervical cancer. METHODS: Colour Doppler ultrasound (Experimental group) and two-dimensional ultrasound (Control group) are used to monitor cervical cancer and assess the treatment effects. PFS, CI, HR, DCR, ORR, PR, SD, PD, ROD, sensitivity, and specificity, accuracy between the two groups were collected and analyzed. RESULTS: A total of 50 patients are included in this study, and the results show that PFS (Experimental group (EG) 5.8±2.2 versus Control group (CG) 6.1±2.6), CI (EG 20% versus CG 16%), HR (EG0.31±0.18 versus CG 0.36±0.21), DCR (EG 80% versus CG 84%), ORR(EG 28% versus CG 36%), PR (EG 16% versus CG 20%), SD (EG 48% versus CG 56%), PD (EG 12% versus CG 16%) (EG 12% versus CG 16%), ROD(EG 44% versus CG 52%) between the two groups are >0.05, and the values of sensitivity (EG 75.6% versus CG 40.2%), specificity (EG 78.4% versus CG 43.3%), and accuracy(EG 80.5% versus CG 41.4%) between the two groups are<0.05. CONCLUSION: Both Colour Doppler ultrasound and two-dimensional ultrasound are effective methods to evaluate the efficacy of concurrent chemo-radiotherapy in patients with cervical cancer.

A Kaposi's sarcoma-associated herpes virus-encoded microRNA contributes to dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is the leading cause of heart transplantation. By microRNA (miRNA) array, a Kaposi's sarcoma-associated herpes virus (KSHV)-encoded miRNA, kshv-miR-K12-1-5p, was detected in patients with DCM. The KSHV DNA load and kshv-miR-K12-1-5p level in plasma from 696 patients with DCM were measured and these patients were followed-up. Increased KSHV seropositivity and quantitative titers were found in the patients with DCM compared with the non-DCM group (22.0% versus 9.1%, p < 0.05; 168 versus 14 copies/mL plasma, p < 0.05). The risk of the individual end point of death from cardiovascular causes or heart transplantation was increased among DCM patients with the KSHV DNA seropositivity during follow-up (adjusted hazard ratio 1.38, 95% confidence interval 1.01-1.90; p < 0.05). In heart tissues, the KSHV DNA load was also increased in the heart from patients with DCM in comparison with healthy donors (1016 versus 29 copies/105 cells, p < 0.05). The KSHV and kshv-miR-K12-1-5p in DCM hearts were detected using immunofluorescence and fluorescence staining in situ hybridization. KSHV itself was exclusively detectable in CD31-positive endothelium, while kshv-miR-K12-1-5p could be detected in both endothelium and cardiomyocytes. Moreover, kshv-miR-K12-1-5p released by KSHV-infected cardiac endothelium could disrupt the type I interferon signaling pathway in cardiomyocytes. Two models of kshv-miR-K12-1-5p overexpression (agomiR and recombinant adeno-associated virus) were used to explore the roles of KSHV-encoded miRNA in vivo. The kshv-miR-K12-1-5p aggravated known cardiotropic viruses-induced cardiac dysfunction and inflammatory infiltration. In conclusion, KSHV infection was a risk factor for DCM, providing developmental insights of DCM involving virus and its miRNA ( https://clinicaltrials.gov . Unique identifier: NCT03461107).

miR-320a induces pancreatic ß cells dysfunction in diabetes by inhibiting MafF.

A variety of studies indicate that microRNAs (miRNAs) are involved in diabetes. However, the direct role of miR-320a in the pathophysiology of pancreatic ß cells under diabetes mellitus remains unclear. In the current study, islet transplantation and hyperglycemic clamp assays were performed in miR-320a transgenic mice to explore the effects of miR-320a on pancreatic ß cells in vivo. Meanwhile, ß cell-specific overexpression or inhibition of miR-320a was delivered by adeno-associated virus (AAV8). In vitro, overexpression or downregulation of miR-320a was introduced in cultured rat islet tumor cells (INS1). RNA immunoprecipitation sequencing (RIP-Seq), luciferase reporter assay, and western blotting were performed to identify the target genes. Results showed that miR-320a was increased in the pancreatic ß cells from high-fat-diet (HFD)-treated mice. Overexpression of miR-320a could not only deteriorate the HFD-induced pancreatic islet dysfunction, but also initiate pancreatic islet dysfunction spontaneously in vivo. Meanwhile, miR-320a increased the ROS level, inhibited proliferation, and induced apoptosis of cultured ß cells in vitro. Finally, we identified that MafF was the target of miR-320a that responsible for the dysfunction of pancreatic ß cells. Our data suggested that miR-320a could damage the pancreatic ß cells directly and might be a potential therapeutic target of diabetes.

Expression Profiles and Potential Functions of Long Non-Coding RNAs in the Heart of Mice With Coxsackie B3 Virus-Induced Myocarditis.

Aims: Long non-coding RNAs (lncRNAs) are critical regulators of viral infection and inflammatory responses. However, the roles of lncRNAs in acute myocarditis (AM), especially fulminant myocarditis (FM), remain unclear. Methods: FM and non-fulminant myocarditis (NFM) were induced by coxsackie B3 virus (CVB3) in different mouse strains. Then, the expression profiles of the lncRNAs in the heart tissues were detected by sequencing. Finally, the patterns were analyzed by Pearson/Spearman rank correlation, Kyoto Encyclopedia of Genes and Genomes, and Cytoscape 3.7. Results: First, 1,216, 983, 1,606, and 2,459 differentially expressed lncRNAs were identified in CVB3-treated A/J, C57BL/6, BALB/c, and C3H mice with myocarditis, respectively. Among them, 88 lncRNAs were commonly dysregulated in all four models. Quantitative real-time polymerase chain reaction analyses further confirmed that four out of the top six commonly dysregulated lncRNAs were upregulated in all four models. Moreover, the levels of ENSMUST00000188819, ENSMUST00000199139, and ENSMUST00000222401 were significantly elevated in the heart and spleen and correlated with the severity of cardiac inflammatory infiltration. Meanwhile, 923 FM-specific dysregulated lncRNAs were detected, among which the levels of MSTRG.26098.49, MSTRG.31307.11, MSTRG.31357.2, and MSTRG.32881.28 were highly correlated with LVEF. Conclusion: Expression of lncRNAs is significantly dysregulated in acute myocarditis, which may play different roles in the progression of AM.

Increased miR-188-3p in Ovarian Granulosa Cells of Patients with Polycystic Ovary Syndrome.

MicroRNA-target networks are often dysregulated in diseases. Our purpose is to investigate this dysregulation of polycystic ovary syndrome (PCOS). Through the bioinformatics reanalysis of the public RNAseq dataset, we found that miR-188-3p was the miRNA with the highest induction rate, and indicated that miR-188-3p might have a rare function of upregulating its targeted expression. This discovery will increase our understanding of the pathology of PCOS and provide new targets for treatment strategies.

LncRNA ZNF593-AS Alleviates Contractile Dysfunction in Dilated Cardiomyopathy.

[Figure: see text].

A Key GWAS-Identified Genetic Variant Contributes to Hyperlipidemia by Upregulating miR-320a.

It has been unclear whether the elevated levels of the circulating miR-320a in patients with coronary artery disease is due to environmental influence or genetic basis. By recombinant adeno-associated virus (rAAV)-mediated loss- and gain-of-function studies in the mouse liver, we revealed that elevated miR-320a is sufficient to aggravate diet-induced hyperlipidemia and hepatic steatosis. Then, we analyzed the data from published genome-wide association studies and identified the rs12541335 associated with hyperlipidemia. We demonstrated that the rs13282783 T allele indeed obligated the silencer activity by preventing the repressor ZFP161 and co-repressor HDAC2 from binding to DNA that led to miR-320a upregulation. We further confirmed this genetic connection on an independent population and through direct genome editing in liver cells. Besides environmental (diet) influence, we established a genetic component in the regulation of miR-320a expression, which suggest a potential therapeutic avenue to treat coronary artery disease by blocking miR-320a in patient liver.

The Cell Type-Specific Functions of miR-21 in Cardiovascular Diseases.

Cardiovascular diseases are one of the prime reasons for disability and death worldwide. Diseases and conditions, such as hypoxia, pressure overload, infection, and hyperglycemia, might initiate cardiac remodeling and dysfunction by inducing hypertrophy or apoptosis in cardiomyocytes and by promoting proliferation in cardiac fibroblasts. In the vascular system, injuries decrease the endothelial nitric oxide levels and affect the phenotype of vascular smooth muscle cells. Understanding the underlying mechanisms will be helpful for the development of a precise therapeutic approach. Various microRNAs are involved in mediating multiple pathological and physiological processes in the heart. A cardiac enriched microRNA, miR-21, which is essential for cardiac homeostasis, has been demonstrated to act as a cell-cell messenger with diverse functions. This review describes the cell type-specific functions of miR-21 in different cardiovascular diseases and its prospects in clinical therapy.

The nuclear and cytoplasmic roles of miR-320 in non-alcoholic fatty liver disease.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder worldwide. Multiple metabolic disorders, such as hyperlipidemia, hyperglycemia, insulin resistance and obesity, have been reportedly associated with NAFLD, but little is known about the detailed mechanisms. METHODS AND RESULTS: Here, we explored the effects of multiple metabolic disorders, especially hyperglycemia on lipid accumulation in liver using several well-established animal models. We found that liver lipid deposition was increased in both type 1 diabetes and high-fat diet (HFD) induced hyperlipidemia models, suggesting that either hyperglycemia or hyperlipidemia alone or together was able to trigger NAFLD. Moreover, we tested whether miR-320, a miRNA promoting lipid accumulation in heart revealed by our previous study, also participated in NAFLD. Though miR-320 treatment further increased liver lipid deposition in type 1 diabetes and HFD-feeding mice, it showed no effect in leptin-receptor deficient db/db mice. Interestingly, miR-320 affected different target genes in cytosol and nucleus, respectively, which collectively led to liver lipid overload. CONCLUSIONS: Our findings illustrated the complex roles of miRNAs in subcellular fractions including nucleus and cytoplasm, which may lead to new insights into the mechanisms and treatment strategies for NAFLD in the future.

Acid-sensing ion channel 1a mediates acid-induced pyroptosis through calpain-2/calcineurin pathway in rat articular chondrocytes.

The pyroptosis is a causative agent of rheumatoid arthritis, a systemic autoimmune disease merged with degenerative articular cartilage. Nevertheless, the precise mechanism of extracellular acidosis on chondrocyte pyroptosis is largely unclear. Acid-sensing ion channels (ASICs) belong to an extracellular H+ -activated cation channel family. Accumulating evidence has highlighted activation of ASICs induced by extracellular acidosis upregulate calpain and calcineurin expression in arthritis. In the present study, to investigate the expression and the role of acid-sensing ion channel 1a (ASIC1a), calpain, calcineurin, and NLRP3 inflammasome proteins in regulating acid-induced articular chondrocyte pyroptosis, primary rat articular chondrocytes were subjected to different pH, different time, and different treatments with or without ASIC1a, calpain-2, and calcineurin, respectively. Initially, the research results showed that extracellular acidosis-induced the protein expression of ASIC1a in a pH- and time-dependent manner, and the messenger RNA and protein expressions of calpain, calcineurin, NLRP3, apoptosis-associated speck-like protein, and caspase-1 were significantly increased in a time-dependent manner. Furthermore, the inhibition of ASIC1a, calpain-2, or calcineurin, respectively, could decrease the cell death accompanied with the decreased interleukin-1ß level, and the decreased expression of ASIC1a, calpain-2, calcineurin, and NLRP3 inflammasome proteins. Taken together, these results indicated the activation of ASIC1a induced by extracellular acidosis could trigger pyroptosis of rat articular chondrocytes, the mechanism of which might partly be involved with the activation of calpain-2/calcineurin pathway.

Identification of ncRNA-Mediated Functions of Nucleus-Localized miR-320 in Cardiomyocytes.

In recent years, systematic analyses of the subcellular distribution of microRNAs (miRNAs) suggest that the majority of miRNAs are present in both nuclear and cytoplasmic compartments. However, the full extent of nuclear miRNA function in cardiomyocytes is currently unknown. Here, subcellular fractionation, followed by the miRNA microarray, revealed that most miRNAs were detectable in both nuclear and cytoplasmic fractions of cardiomyocytes. We employed miR-320 as an example to explore the function of nucleus-localized miRNAs, finding that CRISPR-Cas9-mediated Ago2 knockdown abolished miR-320-induced transcriptional remodeling. Furthermore, nuclear Ago2 re-expression restored the effects of miR-320 in the nucleus. Moreover, liquid chromatography-mass spectrometry (LC-MS) analysis revealed the association of nuclear Ago2 with transcription factors YLP motif-containing protein 1 (Ylpm1) and single-stranded DNA binding protein 1 (Ssbp1). Intersection of the data of transcriptome-sequencing (seq) with Ago2-chromatin immunoprecipitation (ChIP)-seq revealed that the binding of Ago2 with the target promoter DNA may require promoter RNAs. Specifically, Cep57 was upregulated, whereas Fscn2 was downregulated by miR-320, and a similar effect was also observed by knockdown of their promoter RNA, respectively. Chromatin isolation by RNA purification (ChIRP) analysis showed decreased binding of the Cep57 and Fscn2 promoter RNA on their promoter DNA by miR-320 overexpression.Our work provided a preliminary idea that promoter RNA transcripts act as "pioneers" to disrupt chromatin that permits Ago2/miR-320 complexes to target Cep57 or Fscn2 promoter DNA for transcriptional regulation. miRNAs are naturally located in both cytoplasm and nucleus; however, their pathophysiological functions are largely unknown. Our work provided a theoretical basis for developing nuclear miRNA-based therapeutics against various diseases in the future.

Nuclear miR-665 aggravates heart failure via suppressing phosphatase and tensin homolog transcription.

Although numerous miRNAs have been discovered, their functions in the different subcellular organelles have remained obscure. In this study, we found that miR-665 was enriched in the nucleus of cardiomyocytes, and then investigated the underlying role of nuclear miR-665 in heart failure. RNA fluorescence in situ hybridization assays in human heart tissue sections and primary cardiomyocytes showed that miR-665 was localized in the nucleus of cardiomyocytes. Increased expression of nuclear miR-665 was observed not only in the cardiomyocytes isolated from the heart of mice treated in vivo by transverse aortic constriction (TAC), but also in phenylephrine (PE)-treated cultured cardiomyocytes in vitro. To further explore the role of miR-665 in heart failure, a type 9 recombinant adeno-associated virus (rAAV) system was employed to manipulate the expression of miR-665 in mice. Overexpression of miR-665 aggravated TAC-induced cardiac dysfunction, while down-expression of miR-665 showed opposite effects. Bioinformatic prediction and biological validation confirmed that the PTEN (phosphatase and tensin homolog) gene was one of the targets of miR-665 in the nucleus. Furthermore, restoring PTEN expression significantly eliminated the destructive effects of miR-665 over-expression in TAC-induced cardiac dysfunction. Our data showed that nuclear miR-665 aggravates heart failure via inhibiting PTEN expression, which provided a therapeutic approach for heart failure.

Nuclear miR-320 Mediates Diabetes-Induced Cardiac Dysfunction by Activating Transcription of Fatty Acid Metabolic Genes to Cause Lipotoxicity in the Heart.

RATIONALE: Diabetes mellitus is often associated with cardiovascular complications, which is the leading cause of morbidity and mortality among patients with diabetes mellitus, but little is known about the mechanism that connects diabetes mellitus to the development of cardiovascular dysfunction. OBJECTIVE: We aim to elucidate the mechanism underlying hyperglycemia-induced cardiac dysfunction on a well-established db/db mouse model for diabetes mellitus and diabetic complications that lead to heart failure. METHODS AND RESULTS: We first profiled the expression of microRNAs (miRNAs) by microarray and quantitative reverse transcription polymerase chain reaction on db/db mice and identified miR-320 as a key miRNA associated with the disease phenotype. We next established the clinical relevance of this finding by showing the upregulation of the same miRNA in the failing heart of patients with diabetes mellitus. We demonstrated the causal role of miR-320 in inducing diabetic cardiomyopathy, showing that miR-320 overexpression exacerbated while its inhibition improved the cardiac phenotype in db/db mice. Unexpectedly, we found that miR-320 acts as a small activating RNA in the nucleus at the level of transcription. By chromatin immunoprecipitation sequencing and chromatin immunoprecipitation quantitive polymerase chain reaction analysis of Ago2 (argonaute RISC catalytic component 2) and RNA polymerase II in response to miR-320 induction, we identified CD36 (fatty acid translocase) as a key target gene for this miRNA and showed that the induced expression of CD36 is responsible for increased fatty acid uptake, thereby causing lipotoxicity in the heart. CONCLUSIONS: These findings uncover a novel mechanism for diabetes mellitus-triggered cardiac dysfunction, provide an endogenous case for small activating RNA that has been demonstrated to date only with synthetic RNAs in transfected cells, and suggest a potential strategy to develop a miRNA-based therapy to treat diabetes mellitus-associated cardiovascular complications.

Effects of autophagy on apoptosis of articular chondrocytes in adjuvant arthritis rats.

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease that eventually leads to joint deformities and loss of joint function. Previous studies have demonstrated a close relationship between autophagy and the development of RA. Although autophagy and apoptosis are two different forms of programmed death, the relationship between them in relation to RA remains unclear. In this study, we explored the effect of autophagy on apoptosis of articular chondrocytes in vivo and in vitro. Adjuvant arthritis (AA) and acid-induced primary articular chondrocyte apoptosis were used as in vivo and in vitro models, respectively. Articular chondrocyte autophagy and apoptosis were both observed dynamically in AA rat articular cartilage at different stages (15 days, 25 days and 35 days). Moreover, chondrocyte apoptosis and articular cartilage injury in AA rats were increased by the autophagy inhibitor 3-methyladenine (3-MA) and decreased by the autophagy activator rapamycin. In addition, pre-treatment with 3-MA increased acid-induced chondrocyte apoptosis, while pre-treatment with rapamycin reduced acid-induced chondrocyte apoptosis in vitro. These results suggest that autophagy might be a potential target for the treatment of RA.

The Different Roles of miRNA-92a-2-5p and let-7b-5p in Mitochondrial Translation in db/db Mice.

Excessive reactive oxygen species (ROS) generated in mitochondria is known to be a causal event in diabetic cardiomyopathy. Recent studies suggest that microRNAs (miRNAs) are able to translocate to mitochondria to modulate mitochondrial activities, but the roles of such miRNAs in diabetic cardiomyopathy remain unclear. We observed a marked reduction of mitochondrial gene cytochrome-b (mt-Cytb) in the heart of db/db mice compared with controls. Downregulation of mt-Cytb by small interfering RNA (siRNA) recaptured some key features of diabetes, including elevated ROS production. Microarray revealed that none of the miRNAs were upregulated, but 14 miRNAs were downregulated in mitochondria of db/db heart. miR-92a-2-5p and let-7b-5p targeted mt-Cytb and positively modulated mt-Cytb expression. Re-expression of miR-92a-2-5p and let-7b-5p into cardiomyocytes led to reduced ROS production. Furthermore, recombinant adeno-associated virus (rAAV)-mediated delivery of miR-92a-2-5p, but not let-7b-5p, was sufficient to rescue cardiac diastolic dysfunction in db/db heart. Let-7b-5p not only upregulated mt-Cytb in mitochondria, but also downregulated insulin receptor substrate 1 in cytosol and finally lead to no efficiency for improvement of diastolic dysfunction in db/db mice. Our findings demonstrate that reduced mitochondrial miRNAs contribute to impaired mitochondrial gene expression and elevated ROS production. Re-expression of miR-92a-2-5p enhances mitochondrial translation and reduces ROS production and lipid deposition, which finally rescues diabetic cardiomyopathy.