Mechanical forces play critical roles in the function of living cells. However, the underlying mechanisms of how forces influence nuclear events remain elusive. Here, we show that chromatin deformation as well as force-induced transcription of a green-fluorescent-protein (GFP) tagged bacterial-chromosome dihydrofolate reductase (DHFR) transgene can be visualized in a living cell by using three-dimensional magnetic twisting cytometry to apply local stresses on the cell surface via an Arg-Gly-Asp-coated magnetic bead. Chromatin stretching depended on loading direction. DHFR transcription upregulation was sensitive to load direction and proportional to the magnitude of chromatin stretching. Disrupting filamentous actin or inhibiting actomyosin contraction abrogated or attenuated force-induced DHFR transcription, whereas activating endogenous contraction upregulated force-induced DHFR transcription. Our findings suggest that local stresses applied to integrins propagate from the tensed actin cytoskeleton to the LINC complex and then through lamina-chromatin interactions to directly stretch chromatin and upregulate transcription.

We have previously found that the ether-a-go-go related gene (ERG), a long QT syndrome gene encoding a key K ؉ channel (I Kr ) in cardiac cells, is severely depressed in its expression at the protein level but not at the mRNA level in diabetic subjects. The mechanisms underlying the disparate alterations of ERG protein and mRNA, however, remained unknown. We report here a remarkable overexpression of miR-133 in hearts from a rabbit model of diabetes, and in parallel the expression of serum response factor (SRF), which is known to be a transactivator of miR-133, was also robustly increased. Delivery of exogenous miR-133 into the rabbit myocytes and cell lines produced posttranscriptional repression of ERG, down-regulating ERG protein level without altering its transcript level and caused substantial depression of I Kr , an effect abrogated by the miR-133 antisense inhibitor. Functional inhibition or gene silencing of SRF down-regulated miR-133 expression and increased I Kr density. Repression of ERG by miR-133 likely underlies the differential changes of ERG protein and transcript thereby depression of I Kr , and contributes to repolarization slowing thereby QT prolongation and the associated arrhythmias, in diabetic hearts. Our study provided the first evidence for the pathological role of miR-133 in adult hearts and thus expanded our understanding of the cellular function and pathophysiological roles of miRNAs.Abnormal QT interval prolongation is a prominent electrical disorder and has been proposed a predictor of mortality in patients with diabetes mellitus (DM), 3 presumably because it is associated with an increased risk of sudden cardiac death consequent to lethal ventricular arrhythmias (1-8). Our recent study revealed that the long QT syndrome gene, human ethera-go-go-related gene (HERG) encoding the channel responsible for rapid delayed rectifier K ϩ current (I Kr ), is significantly down-regulated in its expression in diabetic hearts and this down-regulation contributes critically to diabetic repolarization slowing and QT prolongation (9, 10). Strikingly, HERG expressions at transcriptional and post-transcriptional levels diverge in diabetic hearts, with its protein levels being reduced by some 60% while the mRNA levels remaining essentially unaltered (10). These disparate changes indicate that HERG expression is impaired mainly at the post-transcriptional level; however, it remained unclear what are the determinants for the differential regulations of HERG expression at protein and transcript levels.MicroRNAs (miRNAs) are endogenous ϳ22-nucleotide non-coding RNAs that anneal to inexactly complementary sequences in the 3Ј-untranslated regions of target mRNAs of protein-coding genes to regulate gene expression. The major characteristics of miRNA actions is to specify translational repression without affecting the levels of the targeted mRNA (11, 12). Among Ͼ300 miRNAs identified thus far, miR-1 and miR-133 are known to specifically express in adult cardiac and skeletal muscle tissues (13,14). Recent stud...

This study investigated the biodegradation potential of 3-(14)C,1H,1H,2H,2H-perfluorodecanol [CF3(CF2)6(14)CF2CH2CH2OH, 14C-labeled 8-2 telomer B alcohol or 14C-labeled 8-2 TBA] by diluted activated sludge from a domestic wastewater treatment plant under aerobic conditions. After sample extraction with acetonitrile, biotransformation products were separated and quantified by LC/ARC (on-line liquid chromatography/accurate radioisotope counting) with a limit of quantification about 0.5% of the 14C counts applied to the test systems. Identification of biotransformation products was performed by quadrupole time-of-flight mass spectrometry. Three transformation products have been identified: CF3(CF2)6(14)CF2CH2COOH (8-2 saturated acid); CF3(CF2)6(14)CF=CHCOOH (8-2 unsaturated acid); and CF3(CF2)6(14)COOH (perfluorooctanoic acid, PFOA), representing 27, 6.0, and 2.1% of the initial 14C mass (14C counts applied) after 28 days, respectively. A transformation product, not yet reported in the literature, has also been observed and tentatively identified as CF3(CF2)6(14)CH2CH2COOH (2H,2H,3H,3H-perfluorodecanoic acid); it accounted for 2.3% of the mass balance after 28 days. The 2H,2H,3H,3H-perfluorodecanoic acid is likely a substrate for beta-oxidation, which represents one of the possible pathways for 8-2 telomer B alcohol degradation. The 8-2 saturated acid and 8-2 unsaturated acid cannot be directly used as substrates for beta-oxidation due to the proton deficiency in their beta-carbon (C3 carbon) and their further catabolism may be catalyzed by some other still unknown mechanisms. The 2H,2H,3H,3H-perfluorodecanoic acid may originate either from the major transformation product CF3(CF2)6(14)CF2CH2COOH or from other unidentified transformation products via multiple steps. Approximately 57% of the starting material remained unchanged after 28 days, likely due to its strong adsorption to the PTFE (poly(tetrafluoroethylene)) septa of the test vessels. No CF3(CF2)6(14)CF2COOH (perfluorononanoic acid) was observed, indicating that alpha-oxidation of CF3(CF2)6(14)CF2CH2COOH did not occur under the study conditions. Several 14C-labeled transformation products that have not yet been identified (each less than 1% of the mass balance) were also observed and together accounted for 7% of the total 14C mass balance after 28 days. It is not clear whether these unidentified transformation products were resulting from further metabolism of 8-2 saturated acid or 8-2 unsaturated acid. The results suggest that perfluorinated acid metabolites such as perfluorooctanoic acid account for only a very small portion of the transformation products observed. Also, the observed volatility and bioavailability of 14C-labeled 8-2 TBA for microbial degradation was markedly decreased as a result of the presence of a strongly adsorbing matrix such as PTFE in the experimental systems. It is apparent that the biological fate of 8-2 telomer B alcohol is determined by multiple degradation pathways, with neither beta-oxidation nor any other enzyme-catalyzed rea...

Previous studies have demonstrated that chronic brain hypoperfusion (CBH) causes A␤ aggregation by upregulating expression of amyloid precursor protein (APP) and ␤-site APP cleaving enzyme 1 (BACE1) protein, which is accompanied by cognitive impairment, but the mechanisms are not fully understood. In this study, we evaluated the effect of microRNA on memory impairment in rats induced by CBH. We show here that CBH generated by bilateral common carotid artery occlusion (2VO) significantly decreased the learning and memory ability in rats, as assessed by Morris water maze, and upregulated expression of APP and BACE1 proteins in the hippocampus and cortex of rats, as evaluated by Western blot and immunofluorescence. In reciprocal, qRT-PCR analysis showed that microRNA-195 (miR-195) was downregulated in both the hippocampus and cortex of rats following CBH, and in the plasma of dementia patients. APP and BACE1 proteins were downregulated by miR-195 overexpression, upregulated by miR-195 inhibition, and unchanged by binding-site mutation or miR-masks, indicating that APP and BACE1 are two potential targets for miR-195. Knockdown of endogenous miR-195 by lentiviral vector-mediated overexpression of its antisense molecule (lenti-pre-AMO-miR-195) elicited dementia in rats, whereas overexpression of miR-195 using lenti-pre-miR-195 reduced dementia vulnerability triggered by 2VO. Additionally, chromatin immunoprecipitation analysis showed that NFB was bound to the promoter region of miR-195 and inhibited its expression. We conclude that miR-195 may play a key role in determining dementia susceptibility in 2VO rats by regulating APP and BACE1 expression at the post-transcriptional level, and exogenous complement of miR-195 may be a potentially valuable anti-dementia approach.

Accumulating evidence demonstrated that bone marrow-derived mesenchymal stem cells (BMSCs) may transdifferentiate into cardiomyocytes and replace apoptotic myocardium so as to improve functions of damaged hearts. However, little information is known about molecular mechanisms underlying myogenic conversion of BMSCs. microRNAs as endogenous noncoding small molecules function to inhibit protein translation post-transcriptionally by binding to complementary sequences of targeted mRNAs. Here, we reported that miR-124 was remarkably downregulated during cardiomyocyte differentiation of BMSCs induced by coculture with cardiomyocytes. Forced expression of miR-124 led to a significant downregulation of cardiac-specific markers-ANP, TNT, and α-MHC proteins as well as reduction of cardiac potassium channel currents in cocultured BMSCs. On the contrary, the inhibition of endogenous miR-124 with its antisense oligonucleotide AMO-124 obviously reversed the changes of ANP, TNT, and α-MHC proteins and increased cardiac potassium channel currents. Further study revealed that miR-124 targeted the 3'UTR of STAT3 gene so as to suppress the expression of STAT3 protein but did not affect its mRNA level. STAT3 inhibitors AG490, WP1066, and S3I-201 were shown to attenuate the augmented expression of ANP, TNT, α-MHC, GATA-4 proteins, and mRNAs in cocultured BMSCs with AMO-124 transfection. Moreover, GATA-4 siRNA reduced the expression of ANP, TNT, α-MHC, and GATA-4 proteins but did not impact STAT3 protein in cocultured BMSCs, indicating GATA-4 serves as an effector of STAT3. In summary, we found that miR-124 regulated myogenic differentiation of BMSCs via targeting STAT3 mRNA, which provides new insights into molecular mechanisms of cardiomyogenesis of BMSCs.

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These authors contributed equally to this work. SUMMARYHistone modifications play critical roles in the perception of environmental cues by plants. Here, we report that Shk1 binding protein 1 (SKB1/AtPRMT5), which catalyzes the symmetric dimethylation of histone H4R3 (H4R3sme2), is involved in iron homeostasis in Arabidopsis. The SKB1 lesion mutant exhibited higher iron accumulation in shoots and greater tolerance to iron deficiency than the wild type. The expression of SKB1 was not affected by iron, but the level of H4R3sme2 mediated by SKB1 was related to iron status in plants. We showed by chromatin immunoprecipitation (ChIP) and genome-wide ChIP-seq that SKB1 associated with the chromatin of the Ib subgroup bHLH genes (AtbHLH38, AtbHLH39, AtbHLH100 and AtbHLH101), and symmetrically dimethylated histone H4R3. The quantity of SKB1 that associated with chromatin of the Ib subgroup bHLH genes and the level of H4R3sme2 corresponded to the iron status of plants (higher with increased iron supply and lower when iron was removed). We conclude that SKB1-mediated H4R3sme2 regulates iron homeostasis in Arabidopsis in the context of increasing or decreasing expression of Ib subgroup bHLH genes. Iron deficiency may cause an increase in the disassociation of SKB1 from chromatin of the bHLH genes and a decrease in the level of H4R3sme2, thereby elevating their transcription and enhancing iron uptake. Our findings provide new insight into the molecular mechanisms of iron homeostasis in strategy I plants.

BackgroundIncreasing evidence indicated plasma D-dimer could be regarded as a marker in cancers, however, its role in gastric cancer is still largely unknown.MethodsPlasma D-dimer levels were measured by enzyme linked fluorescent immunoassays and evaluated by receiver operating characteristic (ROC) curves for peritoneal dissemination in gastric cancer and healthy subjects. The overall survival (OS) characteristics were determined using Kaplan–Meier and Cox regression analyses.ResultsThe average of the plasma D-dimer levels for gastric cancer patients was significantly higher than the healthy subjects. A Spearman correlation analysis showed that plasma D-dimer levels correlated with the depth of invasion, lymph node metastasis, peritoneal dissemination, distant metastasis, tumor size and TNM stage. The mean plasma D-dimer level was 2.20±1.51 µg/mL in peritoneal dissemination patients and 1.01±0.79 µg/mL in non-peritoneal dissemination patients (P<0.001). Additionally, the mean plasma D-dimer concentration in patients alive at the final follow-up evaluation was 0.79±0.72 µg/mL,which was significantly lower than the amounts determined for the deceased patients (1.36±1.13 µg/mL) (P<0.001). The AUC of D-dimer was 0.833 (95%CI: 0.780–0.885). At a cut-off value of 1.465 µg/mL, the D-dimer measurement had a sensitivity of 78.00%, a specificity of 83.76% and an accuracy of 82.59%. The median OS was 48.10 months (95% CI: 43.88–52.31) in patients with plasma D-dimer levels less than 1.465 µg/mL and 22.39 months (95% CI: 16.95–27.82) in patients with plasma D-dimer levels exceeding 1.465 µg/mL (log-rank test, P<0.001). Importantly, plasma D-dimer levels exceeding 1.465 µg/mL were significantly associated with poor OS, as determined using a multivariate Cox regression analysis (hazard ratio [HR], 2.28; 95%CI: 1.36–3.81; P = 0.002).ConclusionsPlasma D-dimer levels are increased in gastric cancer patients and may be a valuable biomarker for peritoneal dissemination, with high D-dimer levels predicting poor outcomes for gastric cancer patients.