TET3-mediated novel regulatory mechanism affecting trophoblast invasion and migration: Implications for preeclampsia development

INTRODUCTION

Aberrant expression of genes has been demonstrated to be related to the abnormal function of trophoblasts and lead to the occurrence and progression of Preeclampsia (PE). However, the underlying mechanism of PE has not been elucidated.

METHODS

We performed PCR analysis to investigate TET3 expression in PE placental tissues. Cell assays were performed in HTR-8/SVneo and JAR. Cell invasion and migration events were investigated by transwell assays in vitro. ChIP-PCR and Targeted bisulfite sequencing were conducted to detect the demethylation of related CpG sites in the KLF13 promoter after inhibition of TET3. In conjunction with bioinformatics analysis, luciferase reporter assays were performed to elucidate the mechanism by which miR-544 binds to TET3/KLF13 mRNA.

RESULTS

In this study, we identified genes associated with human extravillous trophoblasts by conducting sc-seq analysis from the GEO. Then, we measured the expression of TET3 in a larger clinical sample. The results showed that TET3, a DNA demethylase, was found to be expressed at much higher levels in the preeclamptic placenta compared to the control. Then, the inhibition of TET3 significantly promoted trophoblast cell migration and invasion. Conversely, TET3 overexpression suppressed cell migration and invasion in vitro. Further RNA sequencing and mechanism analysis indicated that the inhibition of TET3 suppressed the activation of KLF13 by reducing the demethylation of related CpG sites in the KLF13 promoter, thereby transcriptionally inactivating KLF13 expression. Moreover, luciferase reporter assay indicate that TET3 and KLF13 were direct targets of miR-544.

DISCUSSION

This study uncovers a TET3-mediated regulatory mechanism in PE progression and suggests that targeting the placental miR-544-TET3-KLF13-axis might provide new diagnostic and therapeutic strategies for PE.

miR-135b Aggravates Fusobacterium nucleatum-Induced Cisplatin Resistance in Colorectal Cancer by Targeting KLF13

Cisplatin resistance is the main cause of colorectal cancer (CRC) treatment failure, and the cause has been reported to be related to Fusobacterium nucleatum (Fn) infection. In this study, we explored the role of Fn in regulating cisplatin resistance of CRC cells and its underlying mechanism involved. The mRNA and protein expressions were examined by qRT-PCR and western blot. Cell proliferation and cell apoptosis were assessed using CCK8 and flow cytometry assays, respectively. Dual-luciferase reporter gene assay was adopted to analyze the molecular interactions. Herein, our results revealed that Fn abundance and miR-135b expression were markedly elevated in CRC tissues, with a favorable association between the two. Moreover, Fn infection could increase miR-135b expression via a concentration-dependent manner, and it also enhanced cell proliferation but reduced apoptosis and cisplatin sensitivity by upregulating miR-135b. Moreover, KLF13 was proved as a downstream target of miR-135b, of which overexpression greatly diminished the promoting effect of miR-135b or Fn-mediated cisplatin resistance in CRC cells. In addition, it was observed that upstream 2.5 kb fragment of miR-135b promoter could be interacted by β-catenin/TCF4 complex, which was proved as an effector signaling of Fn. LF3, a blocker of β-catenin/TCF4 complex, was confirmed to diminish the promoting role of Fn on miR-135b expression. Thus, it could be concluded that Fn activated miR-135b expression through TCF4/β-catenin complex, thereby inhibiting KLF13 expression and promoting cisplatin resistance in CRC.

Kruppel-like factor 13 acts as a tumor suppressor in thyroid carcinoma by downregulating IFIT1

BACKGROUND

Kruppel-like factor 13 (KLF13) is a transcription factor and plays an important role in carcinogenesis. However, the significance of KLF13 in thyroid carcinoma (THCA) is underdetermined. In this study, we aimed to explore the clinical relevance and function of KLF13 in the progress of THCA.

METHODS

The expression of KLF13 in thyroid carcinoma and normal tissue was investigated by qPCR and IHC assay. The expression of KLF13 and IFIT1 in cell samples was investigated with Western blot assay. Cell proliferation ability was detected with CCK8 and colony formation assay. Cell growth in vivo with or without KLF13 overexpression was evaluated on a xenograft model. Cell migration ability was measured with Transwell assay. Cell cycle was detected with flow cytometer. The downstream genes of KLF13 were screened using RNA-seq assay. Luciferase activity was employed to assess the transcriptional regulation of KLF13 on IFIT1 promoter.

RESULTS

KLF13 expression was downregulated in THCA samples. KLF13 knockdown and overexpression promoted and inhibited the proliferation and migration of THCA cells, respectively. The RNA-seq, RT-qPCR and immunoblotting data showed that KLF13 knockdown significantly potentiated IFIT1 expression at both mRNA and protein levels. Luciferase assays showed that KLF13 suppressed the transcription activity of IFIT1 promoter. Besides, IFIT1 upregulation was critical for the proliferation and migration of THCA cell lines. Lastly, silencing of IFIT1 greatly reversed the proliferation and migration induced by KLF13 knockdown.

CONCLUSIONS

In conclusion, KLF13 may function as an anti-tumor protein in THCA by regulating the expression of IFIT1 and offer a theoretical foundation for treating thyroid carcinoma.

Putting transcriptional brakes on fibrosis: a negative regulator of TGFβ signaling

Due to the pleiotropic effect of transforming growth factor β (TGFβ) signaling inhibition, function-specific targeted inhibition of TGFβ signaling is required. In a recent study, Yang et al. found that Krüppel-like factor (KLF)-13 acts as a negative regulator of TGFβ. Thus, activating KLF13 in fibrotic tissues may protect them from fibrosis by decreasing TGFβ signaling.

Sp1-like protein KLF13 acts as a negative feedback regulator of TGF-β signaling and fibrosis

Transforming growth factor β (TGF-β) is the primary factor that drives fibrosis in most forms of chronic kidney disease. The aim of this study was to identify endogenous regulators of TGF-β signaling and fibrosis. Here, we show that tubulointerstitial fibrosis is aggravated by global deletion of KLF13 and attenuated by adeno-associated virus-mediated KLF13 overexpression in renal tubular epithelial cells. KLF13 recruits a repressor complex comprising SIN3A and histone deacetylase 1 (HDAC1) to the TGF-β target genes, limiting the profibrotic effects of TGF-β. Temporary upregulation of TGF-β induces KLF13 expression, creating a negative feedback loop that triggers the anti-fibrotic effect of KLF13. However, persistent activation of TGF-β signaling reduces KLF13 levels through FBXW7-mediated ubiquitination degradation and HDAC-dependent mechanisms to inhibit KLF13 transcription and offset the anti-fibrotic effect of KLF13. Collectively, our data demonstrate a role of KLF13 in regulating TGF-β signaling and fibrosis.

Long non-coding RNA DANCR alleviates acute myocardial infarction damage via regulating microRNA-509-5p/KLF transcription factor 13 pathway

Acute myocardial infarction (AMI) is the most important cause of death among cardiovascular diseases. Long noncoding RNAs (lncRNAs) have been widely implicated in the regulation of AMI progression. Discrimination antagonizing nonprotein coding RNA (DANCR) alleviated hypoxia-caused cardiomyocyte damages, and the underlying mechanisms remain unclear. Here, we investigated the function and mechanism of DANCR in hypoxia-induced cardiomyocytes and AMI model by enzyme-linked immunosorbent assay, reactive oxygen species and adenosine triphosphate measurement, and mitochondrial activity determination. Additionally, luciferase reporter assay, immunoblotting, and qRT-PCR were performed to validate the interactions between DANCR/miR-509-5p and miR-509-5p/Kruppel-like factor 13 (KLF13). The role of DANCR was also verified in AMI model by overexpression. Our results showed that DANCR expression was significantly downregulated in hypoxia-induced cardiomyocytes or AMI model. Overexpression of DANCR significantly alleviated mitochondrial damages, reduced inflammation, and improved cardiac function in the AMI model. Furthermore, we demonstrated that miR-509-5p/KLF13 axis mediated the protective effect of DANCR. The current study highlighted the critical role of DANCR in alleviating AMI progression through targeting the miR-509-5p/KLF13 signaling axis, suggesting that DANCR may serve as a potential diagnostic marker or therapeutic target for AMI.

KLF13 overexpression protects sepsis-induced myocardial injury and LPS-induced inflammation and apoptosis

Sepsis remains a worldwide public health problem. This study aims to explore the role and mechanism of transcriptional factors (TFs) in sepsis-induced myocardial injury. Firstly, TF KLF13 was selected to explore its role in sepsis-induced myocardial injury. The caecal ligation and puncture (CLP) -induced sepsis mouse model was established and the septic mice were examined using standard histopathological methods. KLF13 expression was detected in the septic mouse heart and was also seen in a lipoploysaccharide (LPS) -induced cellular inflammation model. To explore this further both pro-apoptotic cleaved-caspase3/caspase3 and Bax levels and anti-apoptotic Bcl2 levels were examined, also in both models, In addition inflammatory cytokine (IL-1β, TNF-α, IL-8 and MCP-1) production and IκB-α protein level and p65 phosphorylation were examined in both septic mice and LPS-induced cells. Thus three parameters - cardiomyocyte apoptosis, inflammatory response and NF-κB pathway activation were evaluated under similar conditions. The septic mice showed significant oedema, disordered myofilament arrangement and degradation and necrosis to varying degrees in the myocardial cells. KLF13 was downregulated in both the septic mouse heart and the LPS-induced cellular inflammation model. Furthermore, both models showed abnormally increased cardiomyocyte apoptosis (increased cleaved-caspase3/caspase and Bax protein levels and decreased Bcl2 level), elevated inflammation (increased production of inflammatory cytokines) and the activated NF-κB pathway (increased p65 phosphorylation and decreased IκB-α protein level). KLF13 overexpression notably ameliorated sepsis-induced myocardial injury in vivo and in vitro. KLF13 overexpression protected against sepsis-induced myocardial injury and LPS-induced cellular inflammation and apoptosis via inhibiting the inflammatory pathways (especially NF-κB signalling) and cardiomyocyte apoptosis.

Krüppel-like Factor 13 Promotes HCC Progression by Transcriptional Regulation of HMGCS1-mediated Cholesterol Synthesis

BACKGROUND AND AIMS

Krüppel-like factor (KLF) has a role in the occurrence, development and metabolism of cancer. We aimed to explore the role and potential molecular mechanism of KLF13 in the growth and migration of liver cancer cells.

METHODS

The expression of KLF13 in hepatocellular carcinoma (HCC) tissues was higher than that in normal tissues according to analysis of The Cancer Genome Atlas (TCGA) database. Lentiviral plasmids were used for overexpression and plasmid knockdown of KLF13. Real-time quantitative polymerase chain reaction (qPCR) and western blotting were used to detect mRNA and protein expression in HCC tissues and cells. Cell counting kit-8 (CCK-8), colony formation, cell migration and invasion, and flow cytometry assays were used to assess the in vitro function of KLF13 in HCC cells. The effect of KLF13 on xenograft tumor growth in vivo was evaluated. The cholesterol content of HCC cells was determined by an indicator kit. A dual-luciferase reporter assay and chromatin immunoprecipitation sequencing (ChIP-seq) revealed the binding relationship between KLF13 and HMGCS1.

RESULTS

The expression of KLF13 was upregulated in HCC tissues and TCGA database. KLF13 knockdown inhibited the proliferation, migration and invasion of HepG2 and Huh7 cells and increased the apoptosis of Huh7 cells. The opposite effects were observed with the overexpression of KLF13 in SK-Hep1 and MHCC-97H cells. The overexpression of KLF13 promoted the growth of HCC in nude mice and KLF13 transcription promoted the expression of HMGCS1 and the biosynthesis of cholesterol. KLF13 knockdown inhibited cholesterol biosynthesis mediated by HMGCS1 and inhibited the growth and metastasis of HCC cells.

CONCLUSIONS

KLF13 acted as a tumor promoter in HCC by positively regulating HMGCS1-mediated cholesterol biosynthesis.

Kruppel-like factor 13 inhibits cell proliferation of gastric cancer by inducing autophagic degradation of β-catenin

Zinc protein KLF13 is a tumor-suppressive member of Kruppel-like factors family, and yet the effect of KLF13 on gastric cancer has not been reported. Here, we aimed to investigate the role of KLF13 in gastric cancer and explored underlying molecular mechanisms. Firstly, it was found that KLF13 expression was significantly decreased in gastric cancer tissues and cancer cells compared with adjacent normal tissues and normal gastric epithelial cells, respectively. KEGG_Pathway and GO_BP analyses suggested that KLF13 was associated with CELL_CYCLE and CELL_PROLIFERATION. Then, our results further demonstrated that KLF13 could obviously inhibit gastric cancer proliferation and induce cell arrest at G2/M phase. Mechanistically, KLF13 decreased expressions of β-catenin and its target genes, CCND1 and MYC, via triggering autophagic degradation of β-catenin. KLF13 up-regulation facilitated co-localization and binding of β-catenin with autophagy protein p62, and exogenous overexpression of β-catenin or blocking autophagy process appeared to reverse KLF13-induced inhibition of gastric cancer proliferation. Furthermore, KLF13 overexpression promoted the expression of ubiquitin-conjugating enzyme E2, Ubc13 which is responsible for catalyzing the synthesis of 'Lys-63'-linked polyubiquitin chains and increased the binding of β-catenin with E3 ubiquitin ligase, TRAF6. In vivo, KLF13 overexpression also suppressed xenograft tumor growth of gastric cancer and down-regulated expressions of Ki67, β-catenin, Cyclin D1, and c-Myc in tumor tissues. Collectively, these data firstly demonstrated the involvement of KLF13 in inhibiting cell proliferation of gastric cancer through promoting autophagy-dependent degradation of β-catenin, which reinforced the evidence for suppressive roles of KLF13 in human tumors.

The inhibitory effect of LINC00261 upregulation on the pancreatic cancer EMT process is mediated by KLF13 via the mTOR signaling pathway

PURPOSE

The long noncoding RNA LINC00261 was reported to be involved in carcinogenesis and has been validated as a tumor suppressor in pancreatic cancer (PC); however, how LINC00261 is regulated has not been fully examined. Here, we attempted to investigate the upstream and downstream targets of LINC00261 in PC.

METHODS

LINC00261 expression in PC tissues was examined by the Gene Expression Omnibus (GEO) datasets and the Gene Expression Profiling Interactive Analysis (GEPIA) database. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays were performed to detect the expression level of LINC00261 in PC cells. The location of LINC00261 in PC cells was identified by RNA fluorescence in situ hybridization (RNA-FISH). Cell Counting Kit-8 (CCK-8), cell apoptosis assay, transwell invasion and migration assays testified the critical role of LINC00261 in PC. The luciferase reporter assay was applied to confirm the binding of LINC00261 to its upstream transcription factor KLF13. The changes in LINC00261 related target protein levels were analyzed by Western blotting assay.

RESULTS

LINC00261 was significantly lower in PC tissues and was mainly concentrated in the nucleus. Overexpression of LINC00261 inhibited the invasion and migration of PC cells. Mechanistically, transcription factor KLF13 was confirmed to inhibit the epithelial-mesenchymal transition (EMT) process of PC cells by promoting the transcription of LINC00261 and suppressing the expression of metastasis-associated proteins, such as matrix metalloproteinase MMP2 and vimentin, thus inhibiting the metastasis of PC.

CONCLUSION

LINC00261 regulates PC cell metastasis through the "KLF13-LINC00261-mTOR-P70S6K1-S6" signaling pathway, which provides a significant set of potential PC therapeutic targets.

Long noncoding RNA FTX ameliorates hydrogen peroxide-induced cardiomyocyte injury by regulating the miR-150/KLF13 axis

Background

Myocardial reperfusion is an effective therapy for acute myocardial infarction (AMI). However, ischemia/reperfusion (I/R) injury following myocardial reperfusion is a significant limitation for AMI treatment. Five prime to Xist (FTX) was recognized as a biomarker of multiple diseases, including heart disease. However, the molecular mechanism of FTX in I/R injury is unclear.

Methods

Cell viability was evaluated by using cell counting kit-8 (CCK-8) assay. Apoptosis was analyzed by using a caspase-3 activity detection kit and flow cytometry. The expression of FTX, microRNA (miR)-150, and Kruppel-like factor 13 (KLF13) was measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The interaction of miR-150 and FTX or KLF13 was confirmed by a dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Protein expression of KLF13 was examined by Western blot. The role of FTX was detected in I/R-injured heart tissues in vivo.

Results

Hydrogen peroxide (H₂O₂) induced cardiomyocyte injury by decreasing cell viability and expediting cell apoptosis. However, FTX alleviated cardiomyocyte injury by promoting cell proliferation and restricting cell apoptosis of H9C2 cells that were treated with H₂O₂. In addition, we discovered that FTX directly interacted with miR-150, while KLF13 was a target of miR-150. Rescue experiments showed that miR-150 neutralized the FTX-mediated promotion of cell progression and restriction of cell apoptosis in H9C2 cells treated with H₂O₂. KLF13 knockdown restored the effect of miR-150 on increased proliferation and decrease in apoptosis in H₂O₂-treated cardiomyocytes. Furthermore, FTX enhanced the expression of KLF13 protein through interaction with miR-150. Upregulation of FTX repressed apoptosis in I/R-injured heart tissues in vivo.

Conclusion

FTX relieves H₂O₂-induced cardiomyocyte injury by increasing KLF13 expression via depletion of miR-150, thus providing a novel therapeutic target for the alleviation of I/R injury.

KLF13 suppresses the proliferation and growth of colorectal cancer cells through transcriptionally inhibiting HMGCS1-mediated cholesterol biosynthesis

Background

Colorectal cancer (CRC) is the fourth most deadly malignancy throughout the world. Extensive studies have shown that Krüppel-like factors (KLFs) play essential roles in cancer development. However, the function of KLF13 in CRC is unclear.

Methods

The Cancer Genome Atlas database was applied to analyze the expression of KLF13 in CRC and normal tissues. Lentivirus system was used to overexpress and to knock down KLF13. RT-qPCR and Western blot assays were performed to detect mRNA and protein expression. CCK-8, colony formation, cell cycle analysis and EdU staining were used to assess the in vitro function of KLF13 in CRC cells. Xenografter tumor growth was used to evaluate the in vivo effect of KLF13 in CRC. Cholesterol content was measured by indicated kit. Transcription activity was analyzed by luciferase activity measurement. ChIP-qPCR assay was performed to assess the interaction of KLF13 to HMGCS1 promoter.

Results

KLF13 was downregulated in CRC tissues based on the TCGA database and our RT-qPCR and Western blot results. Comparing with normal colorectal cells NCM460, the CRC cells HT-26, HCT116 and SW480 had reduced KLF13 expression. Functional experiments showed that KLF13 knockdown enhanced the proliferation and colony formation in HT-29 and HCT116 cells. Opposite results were observed in KLF13 overexpressed cells. Furthermore, KLF13 overexpression resulted in cell cycle arrest at G0/G1 phase, reduced EdU incorporation and suppressed tumor growth of HCT116 cells in nude mice. Mechanistically, KLF13 transcriptionally inhibited HMGCS1 and the cholesterol biosynthesis. Knockdown of HMGCS1 suppressed cholesterol biosynthesis and the proliferation of CRC cells with silenced KLF13. Furthermore, cholesterol biosynthesis inhibitor significantly retarded the colony growth in both cells.

Conclusions

Our study reveals that KLF13 acts as a tumor suppressor in CRC through negatively regulating HMGCS1-mediated cholesterol biosynthesis.

Breakpoint Mapping of Symptomatic Balanced Translocations Links the EPHA6, KLF13 and UBR3 Genes to Novel Disease Phenotype

De novo balanced chromosomal aberrations (BCAs), such as reciprocal translocations and inversions, are genomic aberrations that, in approximately 25% of cases, affect the human phenotype. Delineation of the exact structure of BCAs may provide a precise diagnosis and/or point to new disease loci. We report on six patients with de novo balanced chromosomal translocations (BCTs) and one patient with a de novo inversion, in whom we mapped breakpoints to a resolution of 1 bp, using shallow whole-genome mate pair sequencing. In all seven cases, a disruption of at least one gene was found. In two patients, the phenotypic impact of the disrupted genes is well known (NFIA, ATP7A). In five patients, the aberration damaged genes: PARD3, EPHA6, KLF13, STK24, UBR3, MLLT10 and TLE3, whose influence on the human phenotype is poorly understood. In particular, our results suggest novel candidate genes for retinal degeneration with anophthalmia (EPHA6), developmental delay with speech impairment (KLF13), and developmental delay with brain dysembryoplastic neuroepithelial tumor (UBR3). In conclusion, identification of the exact structure of symptomatic BCTs using next generation sequencing is a viable method for both diagnosis and finding novel disease candidate genes in humans.

Detection of de novo del(18)(q22.2) and a familial of 15q13.2-q13.3 microduplication in a fetus with congenital heart defects

OBJECTIVE

We present detection of de novo del(18)(q22.2) and a familial 15q13.2-q13.3 microduplication in a fetus with congenital heart defects (CHD).

CASE REPORT

A 27-year-old, primigravid woman was referred for genetic counseling because of fetal CHD. Prenatal ultrasound at 17 weeks of gestation revealed pericardial effusion, cardiomegaly and a large ventricular septal defect. The pregnancy was subsequently terminated at 18 weeks of gestation, and a 192-g female fetus was delivered with facial dysmorphism. Cytogenetic analysis of the umbilical cord revealed a karyotype of 46,XX,del(18)(q22.2). The parental karyotypes were normal. Array comparative genomic hybridization (aCGH) of the placental tissue revealed a 2.08-Mb 15q13.2-q13.3 microduplication encompassing KLF13 and CHRNA7, and a 10.74-Mb 18q22.2-q23 deletion encompassing NFATC1. The phenotypically normal father carried the same 2.08-Mb 15q13.2-q13.3 microduplication. Polymorphic DNA marker analysis confirmed a paternal origin of the distal 18q deletion.

CONCLUSION

Prenatal diagnosis of CHD should include a complete genetic study of the embryonic tissues, and the acquired information is useful for genetic counseling.

Downregulation of miR-96 suppresses the profibrogenic functions of cardiac fibroblasts induced by angiotensin II and attenuates atrial fibrosis by upregulating KLF13

Atrial fibrosis is a hallmark of structural remodeling in atrial fibrillation (AF). MicroRNA-96 (miR-96) has been reported to be associated with pulmonary fibrosis and hepatic fibrosis. Nevertheless, the role of miR-96 in atrial fibrosis is still unclear. In our study, we showed that miR-96 is upregulated in human atrial tissues from AF patients and positively correlates with collagen I and collagen III levels. Knockdown of miR-96 reduced angiotensin II (Ang-II)-induced cardiac-fibroblast proliferation, migration, and collagen production, whereas ectopic expression of miR-96 yielded opposite results. Furthermore, we demonstrated that miR-96 represses KLF13 expression, subsequently promoting Ang-II-induced proliferation, migration, and collagen production in murine cardiac fibroblasts. Moreover, we observed that the knockdown of miR-96 attenuated the Ang-II-induced atrial fibrosis in a mouse model of AF. All the findings point to a potential target for the prevention or treatment of atrial fibrosis.

Downregulation of KLF13 through DNMT1-mediated hypermethylation promotes glioma cell proliferation and invasion

Background

Recent evidence indicates that Kruppel-like factor 13 (KLF13) has critical roles in regulating cell differentiation, proliferation and may function as a tumor suppressor. However, its role in glioma progression is poorly understood.

Methods

Public database was used to explore the expression and prognostic value of KLF13 in glioma. Cell proliferation and invasion assays were used to explore the role of KLF13. Bisulfite sequencing and ChIP assay were used to determine the methylation of KLF13 promoter in glioma and the regulation of KLF13 by DNMT1.

Results

We found that KLF13 inhibited glioma cell proliferation and invasion, which could be reversed by AKT activation. DNMT1-mediated hypermethylation was responsible for downregulation of KLF13. Knocking down of DNMT1 restored KFL13 expression and inhibited cell proliferation and invasion as well. Patients with high expression of KLF13 might have a better prognosis.

Conclusion

KLF13 suppressed glioma aggressiveness and the regulation of KLF13 could be a potential therapeutic target.

miR-106b-responsive gene landscape identifies regulation of Kruppel-like factor family

MicroRNA dysregulation is a common feature of cancer and due to the promiscuity of microRNA binding this can result in a wide array of genes whose expression is altered. miR-106b is an oncomiR overexpressed in cholangiocarcinoma and its upregulation in this and other cancers often leads to repression of anti-tumorigenic targets. The goal of this study was to identify the miR-106b-regulated gene landscape in cholangiocarcinoma cells using a genome-wide, unbiased mRNA analysis. Through RNA-Seq we found 112 mRNAs significantly repressed by miR-106b. The majority of these genes contain the specific miR-106b seed-binding site. We have validated 11 genes from this set at the mRNA level and demonstrated regulation by miR-106b of 7 proteins. Combined analysis of our miR-106b-regulated mRNA data set plus published reports indicate that miR-106b binding is anchored by G:C pairing in and near the seed. Novel targets Kruppel-like factor 2 (KLF2) and KLF6 were verified both at the mRNA and at the protein level. Further investigation showed regulation of four other KLF family members by miR-106b. We have discovered coordinated repression of multiple members of the KLF family by miR-106b that may play a role in cholangiocarcinoma tumor biology.

miR-425-5p Inhibits Differentiation and Proliferation in Porcine Intramuscular Preadipocytes

Intramuscular fat (IMF) content affects the tenderness, juiciness, and flavor of pork. An increasing number of studies are focusing on the functions of microRNAs (miRs) during porcine intramuscular preadipocyte development. Previous studies have proved that miR-425-5p was enriched in porcine skeletal muscles and played important roles in multiple physiological processes; however, its functions during intramuscular adipogenesis remain unclear. To explore the role of miR-425-5p in porcine intramuscular adipogenesis, miR-425-5p agomir and inhibitor were used to perform miR-425-5p overexpression and knockdown in intramuscular preadipocytes, respectively. Our results showed that the agomir of miR-425-5p dramatically inhibited intramuscular adipogenic differentiation and downregulated the expression levels of adipogenic marker genes PPARγ, FABP4, and FASN, whereas its inhibitor promoted adipogenesis. Interestingly, the agomir repressed proliferation of porcine intramuscular preadipocytes by downregulation of cyclin B and cyclin E. Furthermore, we demonstrated that miR-425-5p inhibited adipogenesis via targeting and repressing the translation of KLF13. Taken together, our findings identified that miR-425-5p is a novel inhibitor of porcine intramuscular adipogenesis possibly through targeting KLF13 and subsequently downregulating PPARγ.

KLF13 promotes porcine adipocyte differentiation through PPARγ activation

Background

Adipogenesis is tightly controlled by a complex network of transcription factors acting at different stages of differentiation. Kruppel-like factors (KLFs) as a family of zinc-finger transcription factors play diverse roles during cell differentiation and development in mammals.

Results

In the present study, we showed that KLF13 acts as a key regulator regulating porcine adipocyte differentiation. The expression of KLF13 was markedly up-regulated during the early stage of porcine adipocyte differentiation, which was followed by expression of PPARγ. Porcine adipocyte differentiation was significantly attenuated by the addition of siRNA against KLF13, whereas overexpression of KLF13 resulted in enhanced porcine adipocyte differentiation. Using promoter deletion and mutation analysis, we identified a KLF13-binding site within −593/-577 region of the porcine PPARγ proximal promoter, indicating that KLF13 directly interacts with porcine PPARγ promoter. However, inhibition of KLF13 by siRNA did not impair mouse adipocyte differentiation. In addition, knockdown and/or overexpression of KLF13 in 3 T3-L1 cells all did not influence expression of PPARγ2.

Conclusions

Collectively, our results suggest that KLF13 exist as a key pro-adipogenic transcription factor through transactivating PPARγ expression in porcine adipocyte differentiation, whereas no such effect was detected in mouse adipocyte differentiation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13578-015-0016-z) contains supplementary material, which is available to authorized users.

miR-125a-5p regulates differential activation of macrophages and inflammation

Macrophage activation is a central event in immune responses. Macrophages undergoing classical activation (M1 macrophages) are proinflammatory, whereas alternatively activated macrophages (M2 macrophages) are generally anti-inflammatory. miRNAs play important regulatory roles in inflammatory response. However, the manner in which miRNAs regulate macrophage activation in response to different environmental cues has not been well defined. In this study, we found that M-BMM macrophages (M2) express greater levels of miR-125a-5p than do GM-BMM macrophages (M1). Stimulation of macrophages through TLR2 and TLR4 but not through TLR3 enhanced miR-125a-5p expression. Up-regulation of miR-125a-5p after TLR2/4 activation requires the adaptor MYD88 but not TRIF. Overexpression of miR-125a-5p diminished M1 phenotype expression induced by LPS but promoted M2 marker expression induced by IL-4. In contrast, knockdown of miR-125a-5p promoted M1 polarization and diminished IL-4-induced M2 marker expression. We found that miR-125a-5p targets KLF13, a transcriptional factor that has an important role in T lymphocyte activation and inflammation. KLF13 knockdown had similar effects on M1 activation as did miR-125a-5p overexpression. In addition, miR-125a-5p regulates phagocytic and bactericidal activities of macrophages. Our data suggest that miR-125a-5p has an important role in suppressing classical activation of macrophages while promoting alternative activation.