• BMB Reports
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• v.52 no.7
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• pp.469-474
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• 2019

Kruppel-like factor 2 (KLF2) has been implicated in the regulation of cell proliferation, differentiation, and survival in a variety of cells. Recently, it has been reported that KLF2 regulates the p65-mediated transactivation of $NF-{\kappa}B$. Although the $NF-{\kappa}B$ pathway plays an important role in the differentiation of osteoclasts and osteoblasts, the role of KLF2 in these bone cells has not yet been fully elucidated. In this study, we demonstrated that KLF2 regulates osteoclast and osteoblast differentiation. The overexpression of KLF2 in osteoclast precursor cells inhibited osteoclast differentiation by downregulating c-Fos, NFATc1, and TRAP expression, while KLF2 overexpression in osteoblasts enhanced osteoblast differentiation and function by upregulating Runx2, ALP, and BSP expression. Conversely, the downregulation of KLF2 with KLF2-specific siRNA increased osteoclast differentiation and inhibited osteoblast differentiation. Moreover, the overexpression of interferon regulatory protein 2-binding protein 2 (IRF2BP2), a regulator of KLF2, suppressed osteoclast differentiation and enhanced osteoblast differentiation and function. These effects were reversed by downregulating KLF2. Collectively, our data provide new insights and evidence to suggest that the IRF2BP2/KLF2 axis mediates osteoclast and osteoblast differentiation, thereby affecting bone homeostasis.

• Development and Reproduction
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• v.26 no.2
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• pp.79-90
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• 2022

Krüppel-like factor 10 (KLF10) regulates various cellular functions, such as proliferation, differentiation and apoptosis, as well as the homeostasis of several types of tissue. In the present study, we attempted a loss-of-function analysis of zebrafish Klf11a and Klf11b, which constitute human KLF10 homologs. Embryos injected with klf11b-morpholino (MO) showed developmental retardation and cell death, whereas klf11a-MO-injected embryos showed normal development. In klf11b-MO-injected embryos, a dramatic increase in the amount of zebrafish p53 mRNA might be the cause of the increase in that of bax. The degree of apoptosis decreased in the klf11b-MO and p53-MO co-injected embryos. These findings imply that KLF10 is a negative regulator of p53-dependent transcription, suggesting that the KLF10/p53 complex may play an important role in apoptosis for maintenance of tissue homeostasis during embryonic development.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.2
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• pp.177-185
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• 2023

The excessive inflammatory response induced by myocardial infarction exacerbates heart injury and leads to the development of heart failure. Recent studies have confirmed the involvement of multiple transcription factors in the modulation of cardiovascular disease processes. However, the role of KLF9 in the inflammatory response induced by cardiovascular diseases including myocardial infarction remains unclear. Here, we found that the expression of KLF9 significantly increased during myocardial infarction. Besides, we also detected high expression of KLF9 in infiltrated macrophages after myocardial infarction. Our functional studies revealed that KLF9 deficiency prevented cardiac function and adverse cardiac remodeling. Furthermore, the downregulation of KLF9 inhibited the activation of NF-κB and MAPK signaling, leading to the suppression of inflammatory responses of macrophages triggered by myocardial infarction. Mechanistically, KLF9 was directly bound to the TLR2 promoter to enhance its expression, subsequently promoting the activation of inflammation-related signaling pathways. Our results suggested that KLF9 is a pro-inflammatory transcription factor in macrophages and targeting KLF9 may be a novel therapeutic strategy for ischemic heart disease.

• Journal of Microbiology and Biotechnology
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• v.31 no.10
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• pp.1358-1365
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• 2021

To clarify the role of long intergenic nonprotein-coding RNA 1232 (LINC01232) in the progression of gastric cancer and the potential mechanism, we analyzed the expression of LINC01232 in TCGA database using the GEPIA online tool, and the LINC01232 level in gastric cancer cell lines was detected by quantitative real time-polymerase chain reaction (qRT-PCR) as well. Cell proliferation assay, colony formation assay, transwell assay and tumor formation experiment in nude mice were conducted to observe the biological behavior changes of gastric cancer cells through the influence of LINC01232 knockdown. LncATLAS database and subcellular isolation assay were used for subcellular distribution of LINC01232 in gastric cancer cells. The interaction among LINC01232, zeste homolog 2 (EZH2) and kruppel-like factor 2 (KLF2) was clarified by RNA-protein interaction prediction (RPISeq), RNA immunoprecipitation (RIP), qRT-PCR and chromatin immunoprecipitation (ChIP) assay. Rescue experiments were further conducted to elucidate the biological function of LINC01232/KLF2 axis in the progression of gastric cancer. LINC01232 was upregulated in stomach adenocarcinoma (STAD) tissues and gastric cancer lines. LINC01232 knockdown inhibited the proliferative capacities of gastric cancer cells in vitro, and impaired in vivo tumorigenicity. LINC01232 was mainly distributed in the cell nucleus where it epigenetically repressed KLF2 expression via binding to the enhancer of EZH2, which was capable of binding to promoter regions of KLF2 to induce histone H3 lysine 27 trimethylation (H3K27me3). LINC01232 exerts oncogenic activities in gastric cancer via inhibition of KLF2, and therefore, the knockdown of KLF2 could reverse the regulatory effect of LINC01232 in the proliferative ability of gastric cancer cells.

• The Journal of Internal Korean Medicine
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• v.39 no.1
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• pp.1-8
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• 2018

Objectives: This study seeks to investigate the effects of Gamidohongsamul-tang (GDT) on the Gene expression levels of eNOS, KLF2, ICAM-1 and VCAM-1 in HUVEC cells. Methods: HUVEC cells were treated at a concentration of 1, 10, 100 (${\mu}g/ml$) of Gamidohongsamul-tang (GDT). To measure the NOS, KLF2, ICAM-1 and VCAM-1 gene expression in HUVEC cells, the synthesized cDNA was subjected to polymerase chain reaction (PCR) and electrophoresis was performed to verify gene expression level. Results: 1. GDT significantly increased eNOS and KLF2 gene expression. 2. GDT significantly reduced ICAM-1 and VCAM-1 gene expression. Conclusions: These experiments suggest that Gamidohongsamul-tang (GDT) regulates gene expression related with anti-dyslipidemic effects in HUVEC cells. In order to clinically apply this to diseases related to dyslipidemia, such as cardiovascular disease, additional in vivo experiments are needed to verify the anti-dyslipidemic effects of GDT.

• Journal of Gastric Cancer
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• v.19 no.4
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• pp.460-472
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• 2019

Purpose: Long noncoding RNA 00703 (LINC00703) was found originating from a region downstream of Kruppel-like factor 6 (KLF6) gene, having 2 binding sites for miR-181a. Since KLF6 has been reported as a target of miR-181a in gastric cancer (GC), this study aims to investigate whether LINC00703 regulates the miR-181a/KLF6 axis and plays a functional role in GC pathogenesis. Materials and Methods: GC tissues, cell lines, and nude mice were included in this study. RNA binding protein immunoprecipitation (RIP) and pull-down assays were used to evaluate interaction between LINC00703 and miR-181a. Quantitative real-time polymerase chain reaction and western blot were applied for analysis of gene expression at the transcriptional and protein levels. A nude xenograft mouse model was used to determine LINC00703 function in vivo. Results: We revealed that LINC00703 competitively interacts with miR-181a to regulate KLF6. Overexpression of LINC00703 inhibited cell proliferation, migration/invasion, but promoted apoptosis in vitro, and arrested tumor growth in vivo. LINC00703 expression was found to be decreased in GC tissues, which was positively correlated with KLF6, but negatively with the miR-181a levels. Conclusions: LINC00703 may have an anti-cancer function via modulation of the miR-181a/KLF6 axis. This study also provides a new potential diagnostic marker and therapeutic target for GC treatment.

• Journal of Life Science
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• v.19 no.11
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• pp.1637-1643
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• 2009

Shikonin, a component of Lithospermum erythrorhizon Sieb. et Zucc, exerts various characteristics such as anti-inflammatory, anti-cancer and anti-obesity functions. To elucidate the molecular mechanism of shikonin-induced inhibition of adipogenesis, we analyzed the mRNA expression level of various adipogenesis-related factors including C/EBPs (CCAAT/enhancerbinding proteins) and $PPAR{\gamma}$ (peroxisome proliferator-activated receptor $\gamma$). The data showed that mRNA expressions of C/$EBP{\beta}$ and C/$EPB{\delta}$ were only slightly changed by shikonin treatment, but mRNA expressions of $PPAR{\gamma}$ and C/$EPB{\alpha}$ were significantly down-regulated. Then, we tested whether upstream regulators of C/$EBP{\beta}$ and $PPAR{\gamma}$ were involved in anti-adipogenesis of shikonin. C/$EBP{\gamma}$ and CHOP (C/EBP homologous protein), which are upstream regulators of C/$EBP{\beta}$, were not affected by shikonin treatment. On the contrary, the mRNA level of KROX20 was markedly down-regulated by shikonin treatment. These results suggest that KROX20 might regulate downstream factors of adipogenesis through C/$EBP{\beta}$-independent pathway. The expression of KLF15 (Kruppel-like factor15), which is a member of KLF family and is a upstream regulator of $PPAR{\gamma}$, was dramatically decreased by shikonin treatment, but KLF2 was not changed. Shikonin had no impact on the expression of KLF5 in the early stage of adipogenesis, but shikonin increased expression of KLF5 in the late stage of adipogenesis. Even though mRNA expression of KLF5 was moderately changed by shikonin treatment, its effect may be small compared with the effect of KLF15, which was markedly inhibited. Taken together, these results suggest that shikonin inhibits adipogenesis through the down-regulation of $PPAR{\gamma}$ and C/$EPB{\alpha}$, which is mediated by the down-regulation of two pro-adipogenic factors, KROX20 and KLF15.

• Journal of Gastric Cancer
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• v.5 no.3 s.19
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• pp.200-205
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• 2005

Purpose: KLF4, a member of the KLF family, is a zinc finger tumor suppressor protein that is critical for gastric epithelial homeostasis. Our aim was to determine whether the altered expression of KLF4 might be associated with gastric cancer development and, if so, to determine to which pathologic parameter it is linked. Materials and Methods: For the construction of the gastric cancer tissue microarray, 84 paraffin-embedded tissues containing gastric cancer areas were cored 3 times and transferred to the recipient master block. The expression pattern of KLF4 was examined on tissue microarray slides by using immunohistochemistry and was compared with pathologic parameters, including histologic type, depth of invasion, lymph node metastasis, and peritoneal dissemination. Results: The KLF4 protein was expressed in cytoplasm and nucleus of superficial and foveolar epithelial cells in the normal gastric mucosa. We found markedly reduced or loss of KLF4 expression in 43 (51.2%) of the 84 gastric cancer tissues. There was no significant correlation between KLF4 expression and pathologic parameters, including histologic type, depth of invasion, lymph node metastasis and peritoneal dissemination. Conclusion: Our findings suggest that altered expression of KLF4 may contribute to abnormal regulation of gastrointestinal epithelial cell growth and differentiation and to the development of Korean gastric cancer, as an early event.

• Journal of Life Science
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• v.20 no.5
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• pp.729-735
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• 2010

In our previous study, it was reported that an herbal mixture, SH21B, inhibits fat accumulation and adipogenesis both in vitro and in vivo models of obesity. SH21B is a mixture composed of seven herbs: Scutellaria baicalensis Georgi, Prunus armeniaca Maxim, Ephedra sinica Stapf, Acorus gramineus Soland, Typha orientalis Presl, Polygala tenuifolia Willd, and Nelumbo nucifera Gaertner (Ratio 3:3:3:3:3:2:2). The aim of this study was to investigate the detailed molecular mechanisms of the effects of SH21B on various regulators of the adipogenesis pathway. During the adipogenesis of 3T3-L1 cells, SH21B significantly decreased the expression levels of central transcription factors of adipogenesis, such as peroxisome proliferator-activated receptor (PPAR)$\gamma$ and CCAAT/enhancer binding protein (C/EBP)$\alpha$. To elucidate the detailed molecular mechanism of the anti-adipogenic effects of SH21B, we examined the expression levels of the various pro-adipogenic or anti-adipogenic regulators of adipogenesis upstream of $PPAR{\gamma}$ and C/$EBP{\alpha}$. The mRNA levels of Krox20 and Kruppel-like factor (KLF) 15, which are pro-adipogenic regulators, were significantly down-regulated by SH21B treatment, whereas the mRNA levels of C/$EBP{\gamma}$ and KLF5 were not changed. KLF2 and C/EBP homologous protein (CHOP), which are anti-adipogenic regulators, were significantly up-regulated by SH21B treatment. These results suggest that the molecular mechanism of the anti-adipogenic effect of SH21B involves both the down-regulations of pro-adipogenic regulators, such as Krox20 and KLF15, and the up-regulations of anti-adipogenic regulators, such as KLF2 and CHOP, which results in the suppression of central transcription factors of adipogenesis including $PPAR{\gamma}$ and C/$EBP{\alpha}$.

• Genomics & Informatics
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• v.11 no.4
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• pp.263-271
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• 2013

We investigated the contribution of genetic variations of KLF5 to basal metabolic rate (BMR) and resting metabolic rate (RMR) and the inhibition of obesity in Korean children. A variation of KLF5 (rs3782933) was genotyped in 62 Korean children. Using multiple linear regression analysis, we developed a model to predict BMR in children. We divided them into several groups; normal versus overweight by body mass index (BMI) and low BMR versus high BMR by BMR. There were no differences in the distributions of alleles and genotypes between each group. The genetic variation of KLF5 gene showed a significant correlation with several clinical factors, such as BMR, muscle, low-density lipoprotein cholesterol, and insulin. Children with the TT had significantly higher BMR than those with CC (p=0.030). The highest muscle was observed in the children with TT compared with CC (p=0.032). The insulin and C-peptide values were higher in children with TT than those with CC (p=0.029 vs. p=0.004, respectively). In linear regression analysis, BMI and muscle mass were correlated with BMR, whereas insulin and C-peptide were not associated with BMR. In the high-BMR group, we observed that higher muscle, fat mass, and C-peptide affect the increase of BMR in children with TT (p < 0.001, p < 0.001, and p=0.018, respectively), while Rohrer's index could explain the usual decrease in BMR (adjust $r^2$=1.000, p < 0.001, respectively). We identified a novel association between TT of KLF5 rs3782933 and BMR in Korean children. We could make better use of the variation within KLF5 in a future clinical intervention study of obesity.