MiR-183-5p Induced by Saturated Fatty Acids Hinders Insulin Signaling by Downregulating IRS-1 in Hepatocytes.

Excessive saturated fatty acids (SFA) uptake is known to be a primary cause of obesity, a widely acknowledged risk factor of insulin resistance and type 2 diabetes. Although specific microRNAs (miRNAs) targeting insulin signaling intermediates are dysregulated by SFA, their effects on insulin signaling and sensitivity are largely unknown. Here, we investigated the role of SFA-induced miR-183-5p in the regulation of proximal insulin signaling molecules and the development of hepatic insulin resistance. HepG2 hepatocytes treated with palmitate and the livers of high-fat diet (HFD)-fed mice exhibited impaired insulin signaling resulting from dramatic reductions in the protein expressions of insulin receptor (INSR) and insulin receptor substrate-1 (IRS-1). Differential expression analysis showed the level of miR-183-5p, which tentatively targets the 3'UTR of IRS-1, was significantly elevated in palmitate-treated HepG2 hepatocytes and the livers of HFD-fed mice. Dual-luciferase analysis showed miR-183-5p bound directly to the 3'UTR of IRS-1 and reduced IRS-1 expression at the post-transcriptional stage. Moreover, transfection of HepG2 hepatocytes with miR-183-5p mimic significantly inhibited IRS-1 expression and hindered insulin signaling, consequently inhibiting insulin-stimulated glycogen synthesis. Collectively, this study reveals a novel mechanism whereby miR-183-5p induction by SFA impairs insulin signaling and suggests miR-183-5p plays a crucial role in the pathogenesis of hepatic insulin resistance in the background of obesity.

Palmitic Acid-Induced miR-429-3p Impairs Myoblast Differentiation by Downregulating CFL2.

MicroRNAs are known to play a critical role in skeletal myogenesis and maintenance, and cofilin-2 (CFL2) is necessary for actin cytoskeleton dynamics and myogenic differentiation. Nonetheless, target molecules and the modes of action of miRNAs, especially those responsible for the inhibitory mechanism on the myogenesis by saturated fatty acids (SFA) or obesity, still remain unclear. Here, we reported the role played by miR-429-3p on CFL2 expression, actin filament dynamics, myoblast proliferation, and myogenic differentiation in C2C12 cells. Palmitic acid (PA), the most abundant SFA in diet, inhibited the myogenic differentiation of myoblasts, accompanied by CFL2 reduction and miR-429-3p induction. Interestingly, miR-429-3p suppressed the expression of CFL2 by targeting the 3'UTR of CFL2 mRNA directly. Transfection of miR-429-3p mimic in myoblasts increased F-actin formation and augmented nuclear YAP level, thereby promoting cell cycle progression and myoblast proliferation. Moreover, miR-429-3p mimic drastically suppressed the expressions of myogenic factors, such as MyoD, MyoG, and MyHC, and impaired myogenic differentiation of C2C12 cells. Therefore, this study unveiled the crucial role of miR-429-3p in myogenic differentiation through the suppression of CFL2 and provided implications of SFA-induced miRNA in the regulation of actin dynamics and skeletal myogenesis.

MiR-96-5p Induced by Palmitic Acid Suppresses the Myogenic Differentiation of C2C12 Myoblasts by Targeting FHL1.

Skeletal myogenesis is a multi-stage process that includes the cell cycle exit, myogenic transcriptional activation, and morphological changes to form multinucleated myofibers. Recent studies have shown that saturated fatty acids (SFA) and miRNAs play crucial roles in myogenesis and muscle homeostasis. Nevertheless, the target molecules and myogenic regulatory mechanisms of miRNAs are largely unknown, particularly when myogenesis is dysregulated by SFA deposition. This study investigated the critical role played by miR-96-5p on the myogenic differentiation in C2C12 myoblasts. Long-chain SFA palmitic acid (PA) significantly reduced FHL1 expression and inhibited the myogenic differentiation of C2C12 myoblasts but induced miR-96-5p expression. The knockdown of FHL1 by siRNA stimulated cell proliferation and inhibited myogenic differentiation of myoblasts. Interestingly, miR-96-5p suppressed FHL1 expression by directly targeting the 3'UTR of FHL1 mRNA. The transfection of an miR-96-5p mimic upregulated the expressions of cell cycle-related genes, such as PCNA, CCNB1, and CCND1, and increased myoblast proliferation. Moreover, the miR-96-5p mimic inhibited the expressions of myogenic factors, such as myoblast determination protein (MyoD), myogenin (MyoG), myocyte enhancer factor 2C (MEF2C), and myosin heavy chain (MyHC), and dramatically impeded differentiation and fusion of myoblasts. Overall, this study highlights the role of miR-96-5p in myogenesis via FHL1 suppression and suggests a novel regulatory mechanism for myogenesis mediated by miRNA in a background of obesity.

CFL2 is an essential mediator for myogenic differentiation in C2C12 myoblasts.

CFL2, a skeletal muscle-specific member of the actin depolymerizing factor/cofilin protein family, is known to be involved in the regulation of actin filament dynamics. Although the impact of CFL2 has been studied in human myopathy, its functional contribution to myogenic differentiation, in terms of its effects on cell proliferation, cell cycle, and myogenic factor modulation, remains largely unknown. Here, we report that CFL2 is required for the myogenic differentiation of C2C12 myoblasts by regulating proliferation and myogenic transcription factors expressions. CFL2 expression was induced during myogenic progression, and its knockdown by siRNA in myoblasts enhanced phalloidin staining, indicating increased filamentous actin formation. Interestingly, CFL2 depletion stimulated cell proliferation and induced a cell cycle shift from G0/G1 to G2/M phases, which are known to inhibit progenitor cell differentiation. CFL2 knockdown markedly downregulated the protein expressions of myogenic transcription factors (MyoD, MyoG, and MEF2C) and thereby impaired the differentiation and myotube formation of C2C12 myoblasts. Collectively, this study highlights the roles played by CFL2 on cell cycle progression and proliferation and suggests a novel regulatory mechanism of myogenic differentiation mediated by CFL2.

MiR-183-5p induced by saturated fatty acids regulates the myogenic differentiation by directly targeting FHL1 in C2C12 myoblasts.

Skeletal myogenesis is a complex process that is finely regulated by myogenic transcription factors. Recent studies have shown that saturated fatty acids (SFA) can suppress the activation of myogenic transcription factors and impair the myogenic differentiation of progenitor cells. Despite the increasing evidence of the roles of miRNAs in myogenesis, the targets and myogenic regulatory mechanisms of miRNAs are largely unknown, particularly when myogenesis is dysregulated by SFA deposition. This study examined the implications of SFA-induced miR-183-5p on the myogenic differentiation in C2C12 myoblasts. Long-chain SFA palmitic acid (PA) drastically reduced myogenic transcription factors, such as myoblast determination protein (MyoD), myogenin (MyoG), and myocyte enhancer factor 2C (MEF2C), and inhibited FHL1 expression and myogenic differentiation of C2C12 myoblasts, accompanied by the induction of miR-183-5p. The knockdown of FHL1 by siRNA inhibited myogenic differentiation of myoblasts. Interestingly, miR-183-5p inversely regulated the expression of FHL1, a crucial regulator of skeletal myogenesis, by targeting the 3'UTR of FHL1 mRNA. Furthermore, the transfection of miR-183-5p mimic suppressed the expression of MyoD, MyoG, MEF2C, and MyHC, and impaired the differentiation and myotube formation of myoblasts. Overall, this study highlights the role of miR-183-5p in myogenic differentiation through FHL1 repression and suggests a novel miRNA-mediated mechanism for myogenesis in a background of obesity. [BMB Reports 2020; 53(11): 605-610].

Alteration of mitochondrial DNA content modulates antioxidant enzyme expressions and oxidative stress in myoblasts.

Mitochondrial dysfunction is closely associated with reactive oxygen species (ROS) generation and oxidative stress in cells. On the other hand, modulation of the cellular antioxidant defense system by changes in the mitochondrial DNA (mtDNA) content is largely unknown. To determine the relationship between the cellular mtDNA content and defense system against oxidative stress, this study examined a set of myoblasts containing a depleted or reverted mtDNA content. A change in the cellular mtDNA content modulated the expression of antioxidant enzymes in myoblasts. In particular, the expression and activity of glutathione peroxidase (GPx) and catalase were inversely correlated with the mtDNA content in myoblasts. The depletion of mtDNA decreased both the reduced glutathione (GSH) and oxidized glutathione (GSSG) slightly, whereas the cellular redox status, as assessed by the GSH/GSSG ratio, was similar to that of the control. Interestingly, the steady-state level of the intracellular ROS, which depends on the reciprocal actions between ROS generation and detoxification, was reduced significantly and the lethality induced by H2O2 was alleviated by mtDNA depletion in myoblasts. Therefore, these results suggest that the ROS homeostasis and antioxidant enzymes are modulated by the cellular mtDNA content and that the increased expression and activity of GPx and catalase through the depletion of mtDNA are closely associated with an alleviation of the oxidative stress in myoblasts.

Saturated fatty acids-induced miR-424-5p aggravates insulin resistance via targeting insulin receptor in hepatocytes.

The excessive intake of saturated fatty acids (SFA) causes obesity and liver steatosis, which are major risk factors for insulin resistance and type 2 diabetes. Although the expression of certain microRNAs (miRNAs) targeting the insulin signaling molecules are regulated aberrantly in SFA-induced obesity, their implications on hepatic insulin resistance are largely unknown. This study examined the associations of miR-424-5p, which is induced by SFA, with the development of insulin resistance. SFA palmitate (PA)-treated HepG2 cells and high fat diet (HFD)-induced obese mouse livers showed an impairment of insulin signaling due to a significant decrease in INSR and IRS-1 expression. Based on expression profiling and qRT-PCR analysis, miR-424-5p, which presumably targets the 3'UTR of INSR, was upregulated in both PA-treated HepG2 cells and the liver of HFD-fed mice. miR-424-5p was found to target the 3'UTR of INSR directly and downregulated INSR expression at the post-transcriptional step. Furthermore, the overexpression of miR-424-5p suppressed INSR expression significantly, leading to impaired insulin signaling and glycogen synthesis in hepatocytes. A novel mechanism for how SFA-induced miR-424-5p impairs insulin signaling through the targeting of INSR is reported. In addition, the crucial role and underlying mechanism of miR-424-5p in the obesity-induced hepatic insulin resistance is explained.

Data on the expression of PEPCK in HepG2 hepatocytes transfected with miR-195.

Dietary fats rich in saturated fatty acid (SFA) increase the risk of metabolic diseases, and certain microRNAs (miRNAs) dysregulated by SFA are associated with the pathogenesis of insulin resistance and type 2 diabetes. A previous study found that miR-195 is increased by SFA and impairs hepatic insulin signaling through the suppression of INSR (Yang et al., 2014) [1]. This article reports accompanying data to determine the effect of miR-195 on the expression of PEPCK, a key player in hepatic gluconeogenesis. The transfection of miR-195 in HepG2 hepatocytes was found to increase the mRNA and protein expression of PEPCK. Moreover, the insulin-stimulated reduction of PEPCK expression was attenuated drastically by miR-195. More detailed analysis and understanding of the role of miR-195 in diet-induced hepatic insulin resistance can be found in "Saturated fatty acid-induced miR-195 impairs insulin signaling and glycogen metabolism in HepG2 cells" (Yang et al., 2014) [1].

Data on the decreased expression of FOXO1 by miR-1271 in HepG2 hepatocytes.

Obesity and metabolic diseases are closely associated with insulin resistance. Obesity-induced miRNAs are also considered to be potential contributors to the development of insulin resistance and type 2 diabetes. Previously, the expression of miR-1271 was reported to be upregulated in the liver of diet-induced obese mice (Yang et al., 2016) [1]. In this data article, multiple in silico analysis predicted FOXO1 gene to be a direct target of miR-1271. Dual luciferase reporter gene analysis showed that miR-1271 suppressed FOXO1 expression by direct binding to 3'UTR. The overexpression of miR-1271 reduced the protein expression of FOXO1, thereby reducing the transcription of PEPCK, a downstream target of FOXO1. The data is related to a research article entitled "MiR-1271 upregulated by saturated fatty acid palmitate provokes impaired insulin signaling by repressing INSR and IRS-1 expression in HepG2 cells" (Yang et al., 2016) [1].

Data on the effect of miR-15b on the expression of INSR in murine C2C12 myocytes.

The ectopic expression of miR-15b is linked causally to impaired insulin signaling in human HepG2 hepatocytes through the suppression of INSR (Yang et al., 2015) [1]. In this data article, we further examined the effect of miR-15b on insulin signaling in a murine skeletal muscle cells, C2C12 myocytes. Although the 3'UTR of mouse INSR mRNA has an appropriate binding site for miR-15b based on TargetScan analysis, the ectopic expression of miR-15b did not suppress the expression and insulin-stimulated phosphorylation of insulin signaling intermediates in C2C12 myocytes. A more detailed understanding of the effects of miR-15b on hepatic insulin resistance can be found in "Obesity-induced miR-15b is linked causally to the development of insulin resistance through the repression of the insulin receptor in hepatocytes" (Yang et al., 2015) [1].

Data on the expression and insulin-stimulated phosphorylation of IRS-1 by miR-96 in L6-GLUT4myc myocytes.

Diets containing a high saturated fatty acid (SFA) increase the risk of metabolic diseases, and microRNAs (miRNAs) induced by SFA have been implicated in the pathogenesis of insulin resistance and type 2 diabetes. In a previous report, miR-96 is found to be upregulated by SFA and involved in the suppression of insulin signaling intermediates, leading to insulin resistance in hepatocytes (Yang et al., 2016) [1]. This article presents the accompanying data collected from L6-GLUT4myc myocytes to determine the effects of miR-96 on insulin signaling in skeletal muscle cells. The transfection of miR-96 decreased the expression of IRS-1 in myocytes. Accordingly, miR-96 inhibited the insulin-stimulated phosphorylation of IRS-1, which led to an impairment of insulin signaling. More detailed analysis and understanding of the roles of miR-96 in diet-induced insulin resistance can be found in "Induction of miR-96 by dietary saturated fatty acids exacerbates hepatic insulin resistance through the suppression of INSR and IRS-1" (Yang et al., 2016) [1].

Dataset on the identification of differentially expressed genes by annealing control primer-based PCR in mitochondrial DNA-depleted myocytes.

Changes in the mitochondrial DNA (mtDNA) content are believed to initiate a stress signal that leads to alterations in nuclear gene expression. This article presents data on the identification of nuclear genes that are expressed differentially in response to changes in the mtDNA content in myocytes using annealing controlled primers (ACP)-based PCR technology. The data obtained from L6 GLUT4myc myocytes showed that a total of 19 ACPs produced differentially expressed PCR amplicons in the mtDNA-depleted myocytes. Among those, 13 amplicons were cloned, sequenced, and identified successfully based on the GenBank database. To validate the efficacy of ACP-based PCR analysis, three differentially expressed genes (DEG10, 22 and 26) were confirmed by PCR using the specific primers. The further analysis and detailed results of DEG22 and its functional significance can be found in "C1q tumor necrosis factor alpha-related protein isoform 5 is increased in mitochondrial DNA-depleted myocytes and activates AMP-activated protein kinase." [1].

MicroRNA expression analysis in the liver of high fat diet-induced obese mice.

A previous study indicated a causal link between certain miRNAs induced by obesity and the development of hepatic insulin resistance and type 2 diabetes. Here we provide accompanying data collected using Affymetrix GeneChip miRNAs microarrays to identify the changes in miRNAs expression in the liver of mice fed a high fat diet (HFD). Differentially expressed microRNA analyses in the liver of the HFD-fed mice revealed a range of upregulated (>1.5-fold) or downregulated (<0.5-fold) miRNAs. Among those upregulated miRNAs, in silico target analysis, such as TargetScan, PicTar, and miRWalk, identified miRNAs with the putative binding sites on the 3'UTRs of INSR and/or IRS-1. Interpretation of the data and further extensive insights into the implication of miRNAs, particularly miR-15b, in hepatic insulin resistance can be found in "Obesity-induced miR-15b is linked causally to the development of insulin resistance through the repression of the insulin receptor in hepatocytes." (W.M. Yang, H.J. Jeong, S.W. Park, W. Lee, 2015)[1].

Induction of miR-96 by Dietary Saturated Fatty Acids Exacerbates Hepatic Insulin Resistance through the Suppression of INSR and IRS-1.

Obesity is defined as the excessive accumulation of body fat that ultimately leads to chronic metabolic diseases. Diets rich in saturated fatty acids (SFA) exacerbate obesity and hepatic steatosis, which increase the risk of hepatic insulin resistance and type 2 diabetes (T2DM). Although microRNAs (miRNAs) play an important role in a range of biological processes, the implications of SFA-induced miRNAs in metabolic dysregulation, particularly in the pathogenesis of hepatic insulin resistance, are not well understood. This study investigated the implications of miR-96, which is induced strongly by SFA, in the development of hepatic insulin resistance. The liver of HFD mice and the palmitate-treated hepatocytes exhibited an impairment of insulin signaling due to the significant decrease in INSR and IRS-1 expression. According to expression profiling and qRT-PCR analysis of the miRNAs, the expression level of miR-96 was higher in hepatocytes treated with palmitate. Moreover, miR-96 was also upregulated in the liver of HFD mice. Interestingly, miR-96 targeted the 3'UTRs of INSR and IRS-1 directly, and repressed the expression of INSR and IRS-1 at the post-transcriptional level. Accordingly, the overexpression of miR-96 was found to cause a significant decrease in INSR and IRS-1 expression, thereby leading to an impairment of insulin signaling and glycogen synthesis in hepatocytes. These results reveal a novel mechanism whereby miR-96 promotes the pathogenesis of hepatic insulin resistance resulted from SFA or obesity.

Data for differentially expressed microRNAs in saturated fatty acid palmitate-treated HepG2 cells.

Certain microRNAs (miRNAs) targeting the molecules in the insulin signaling cascades are dysregulated by saturated fatty acids (SFA), which can lead to insulin resistance and type 2 diabetes. This article reports the accompanying data collected using miRNAs microarrays to identify the changes in miRNA expression in HepG2 cells treated with SFA palmitate. Differentially expressed miRNA analyses in HepG2 cells showed that a range of upregulated (>1.5-fold) or downregulated (<0.5-fold) miRNAs. Further extensive insights into the implications of miRNAs, particularly miR-1271, in HepG2 cells can be found in "MiR-1271 upregulated by saturated fatty acid palmitate provokes impaired insulin signaling by repressing INSR and IRS-1 expression in HepG2 cells" (W.M. Yang, K.H. Min, W. Lee, 2016) [1].

MiR-1271 upregulated by saturated fatty acid palmitate provokes impaired insulin signaling by repressing INSR and IRS-1 expression in HepG2 cells.

Dietary saturated fatty acids (SFA) in excess not only induce hepatic insulin resistance, but also result in type 2 diabetes (T2DM). Although microRNAs (miRNAs) participate widely in the pathogenesis of a range of diseases through the suppression of target gene expression at the post-transcriptional level, the implications of SFA-induced miRNAs in the dysregulation of metabolism, particularly in the development of insulin resistance, are largely unclear. SFA palmitate provoked an impairment of insulin signaling in HepG2 cells via a reduction in the expression of INSR and IRS-1 protein. The significant upregulation of miR-1271, which was presumed to target INSR and IRS-1 3'UTRs, was observed in the palmitate-treated HepG2 cells. Using a reporter gene assay, miR-1271 authentically targeted the 3'UTRs of INSR and IRS-1. Furthermore, the overexpression of miR-1271 caused a substantial decrease in INSR and IRS-1 expression, which led to an impairment in insulin signaling and glycogen metabolism. Therefore, these findings suggest that the induction of miR-1271 by SFA palmitate promotes the development of insulin resistance by targeting INSR and IRS-1 in hepatocytes.

C1q tumor necrosis factor α-related protein isoform 5 attenuates palmitate-induced DNA fragmentation in myocytes through an AMPK-dependent mechanism.

This article reports the data for the effects of C1q tumor necrosis factor α-related protein isoform 5 (CTRP5) on the palmitate-induced apoptosis in myocytes. The data obtained from in vitro cultured myocytes shows that the cellular treatment with the globular domain of CTRP5 (gCTRP5) significantly inhibits the palmitate-induced MTT reduction, caspase-3 activation, and DNA fragmentation in a time-dependent manner. The data presented in this article also shows that AraA, an inhibitor of AMPK, almost completely abolished the protective effect of gCTRP5 on the DNA fragmentation induced by palmitate in myocytes. Interpretation of our data and further extensive insights into the protective role of CTRP5 in palmitate-induced apoptosis in myocytes can be found in Yang and Lee (2014) [1].

Removal of displaced foreign body from the maxillary sinus using replaceable bony windows and saline irrigation, followed by suctioning of the foreign body.

Various surgical techniques for the removal of a foreign body from maxillary sinuses have been reported. However, the access window in the lateral wall of the maxillary sinus cavity is not replaced by a bony wall when sinus grafting is not performed. The replaceable bony window provides an access window into the sinus cavity and maintains the integrity of the lateral wall of the sinus cavity after the removal of a foreign body from the sinus. Saline irrigation and suction are simple and quick techniques to remove foreign bodies from the sinus. This technique does not require special equipment, including that of endoscopy.

Efficacy and tolerability of mirtazapine and sertraline in Korean veterans with posttraumatic stress disorder: a randomized open label trial.

BACKGROUND: The aim of this study was to investigate the potential use of mirtazapine in Korean veterans diagnosed with PTSD, by comparing it with sertraline, a drug approved for use in PTSD in the USA. METHODS: Efficacy was evaluated by the clinician administered PTSD scale (CAPS-2), the Hamilton rating scale for depression (HAMD-17) and the clinical global impression scale (CGI), at baseline and at weeks 1, 2 and 6. A response was defined as a > or = 30 % decrease in CAPS-2 total severity, a > or = 50 % decrease in total HAMD-17 score, and a CGI-I score < 3. RESULTS: 51 patients on mirtazapine (mean age/duration of illness: 59.1/33.5 years) and 49 on sertraline (mean age/duration of illness: 60.6/35.6 years) completed the study. The mean daily dosage was 34.1 mg for mirtazapine and 101.5 mg for sertraline. On the CAPS-2 total score more patients responded in the mirtazapine group at week 1 (13 vs 2 %) and week 2 (51 vs 31 %). At week 6 this difference was statistically significant (88 % vs 69 %, p = 0.039) on the CAPS-2 total score. The HAMD-17 total score and CGI-I score decreased in both groups, with no significant differences between th groups on all time points. The main side effects for the mirtazapine group were: dry mouth (19.6 %), constipation (19.6 %), somnolence (15.7 %) and weight gain (1.96 %); and for the sertraline group: indigestion (14.3 %), palpitation (6.1 %), agitation (2.0 %), epigastric soreness (2.0 %), insomnia (2.0 %) and sexual dysfunction (2.0 %). CONCLUSION: Mirtazapine appeared to be an effective and well-tolerated treatment for PTSD in Korean veterans.