KLF4 Research Articles

Modifications of WNT signaling pathway genes including WNT1, KLF5 and WNT16 in colorectal cancer

IntroductionColorectal cancer (CRC) has a high mortality globally and is classified as a main serious type of cancers. Correspondingly, investigating the fluctuations of key genes in dissimilar signaling pathways, show incompatible performance in carcinogenesis and tumorigenesis. So, WNT signaling (Wnt/β-catenin) is one of the most important in this category. Hence, the alterations of WNT1, KLF5 and WNT16 were measured and analyzed in both tumoral and non tumoral tissues of CRC. Materials and methods72 patients with CRC (according to the confirmation of the pathology department) were involved in this project. Basically, 72 tumoral and 72 non-tumoral tissues of each patient after getting patients agreement in Omid Clinic, Babol city, Iran, were investigated, using Real-time PCR in conjunction with the association of all tissues modifications (staging, grading, metastasis and lymph node) in comparison with all gene's upregulation and downregulation. ResultsThe expression of WNT1, KLF5 and WNT16 genes were upregulated significantly (P = 0.002) importantly, the upregulation of WNT1 expression was associated with tumor size high-grade tumors (P = 0.02), late-stage tumors (P = 0.02) and lymph node metastasis (P = 0.05). WNT16 expression was significantly (P = 0.02) associated with lymph node metastasis. Whereas, other clinicopathological features did not show an association with examined gene expression. ConclusionAll these genes including WNT1, KLF5 and WNT16 had a remarkable upregulation in tumoral tissues. Consequently, the alteration of these genes expression indicated that they can be advised as a main diagnostic biomarker in CRC.

Impact of short-term starvation and refeeding on the expression of KLF15 and regulatory mechanism of branched-chain amino acids metabolism in muscle of Chinese soft-shelled turtle (Pelodiscus sinensis).

The branched-chain amino acids (BCAA) play an important role in muscle energy metabolism, and Krüppel-like factor 15 (KLF15) is an essential regulator of BCAA metabolism in muscle under nutritional deficiency. In this study, we analyzed the effect of normal feeding (starvation for 0day), starvation for 3, 7, 10, 15days, and refeeding for 7days after 15days of starvation on the expression of KLF15 and BCAA metabolism in muscle of Chinese soft-shelled turtles by a fasting-refeeding trial. The results showed that the level of KLF15 transcription was increased first and then decreased in muscle during short-term starvation, and the protein level was gradually increased. Both the mRNA and protein level of the KLF15 returned to normal feeding level after refeeding for 7days. The changing trend of the activities of branched-chain aminotransferase (BCAT) and alanine aminotransferase (ALT) was consistent to that of KLF15 mRNA, but at the transcription level, the expression of BCAT mRNA was consistent with the change of enzyme activity as well as ALT continued to increase in muscle under starvation. In addition, BCAA content showed a trend that decreased first and then increased under starvation, while the alanine (Ala) was the contrary. The above results indicated that the regulatory role of KLF15 in BCAA catabolism of muscle in Chinese soft-shelled turtles under nutritional deficiency, which might be activated the catabolism of BCAA in muscle to provide energy and maintain the homeostasis by KLF15-BACC signaling axis.

SUN-653 Bypassing Skeletal Muscle Lipid Handling Deficiencies as a Therapy for Metabolic Disease

Metabolic diseases and their serious sequelae such as non-alcoholic fatty liver disease (NAFLD) pose a substantial clinical burden. It is now well recognized that skeletal muscle is a major site for the metabolism of all major macronutrients, and derangements in these muscle processes significantly contribute to metabolic disease. Studies over the last 15 years have identified the transcription factor Krüppel-like factor 15 (KLF15) as an important regulator and effector of metabolic processes across various tissues, and furthermore, genome-wide studies have identified human KLF15 variants with increased body mass index and diabetes. Given the importance of skeletal muscle in maintaining metabolic homeostasis, we generated a skeletal muscle specific KLF15 knockout (K15-SKO) mouse to study the role of skeletal muscle KLF15 in regulating systemic metabolism. We found that this animal is prone to developing obesity and insulin resistance at baseline, a phenotype that is greatly exacerbated in response to high fat diet (HFD). Strikingly, K15-SKO mice show a propensity toward developing NAFLD, as demonstrated by increased micro- and macrovesicular steatosis, hepatocellular ballooning, increased hepatic fatty acid and triglyceride deposition, and elevated Cd36 expression. A potential cause of NAFLD is the accumulation of excess lipids and lipid intermediates due to defects in the lipid flux pathway in extrahepatic tissues. Indeed, we see defects in the expression of genes involved in the carnitine shuttle and a paucity of long-chain acylcarnitines in K15-SKO skeletal muscle. Furthermore, RNA sequencing of skeletal muscle from K15-SKO mice shows downregulation in a number of pathways involved in lipid handling. This indicates that KLF15 serves as a novel extrahepatic molecular regulator of hepatic health. It has been previously shown that a diet rich in short-chain fatty acids (SCFA) can bypass defects in lipid handling and ultimately improve metabolic health. To explore this therapeutic avenue, we gave K15-SKO mice either normal chow (NC) or a SCFA-rich diet for 7 weeks. We observed decreased weight gain and improved glucose homeostasis in SCFA-rich diet fed mice. In addition to being a preventative strategy, SCFA-rich diets may also serve as a potential therapy to rescue from metabolic disease. To this end, we gave K15-SKO mice HFD for 5 weeks followed by 7 weeks of either NC or SCFA-rich diet. We observed that providing SCFAs can improve metabolic health and ameliorate the phenotype seen due to defects in skeletal muscle lipid handling: mice given SCFA-rich diet following HFD had significantly decreased weight gain and improved insulin sensitivity. These studies demonstrate that skeletal muscle KLF15 serves as an important regulator of lipid flux and hepatic health, and that SCFA-rich diets are a promising candidate for metabolic disease resultant of impaired lipid handling.

Characterization of mesenchymal stem cells derived from adipose tissue of a cougar (Puma concolor).

Adipose derived mesenchymal stem cells (AMSCs) have been isolated from domestic and wild cats. For wild cats, the isolation of AMSCs has been reported in the black-footed cats (Felis nigripes) and guigna (Leopardus guigna). Stromal vascular fraction (SVF) isolated from cougar adipose tissue have been used to restore elbow functionality in the cougar (Puma concolor) but multipotent characteristics of these cells have not been described. The present study describes for the first time the isolation and characterization of mesenchymal stem cells derived from adipose tissue of cougar. AMSCs and fibroblasts from six months female cougar were isolated and cultured in DMEM/F12, supplemented with FBS 10% + 1% Antibiotic/Antifungal + 2.4 mM L-Glutamine + 2.4 mM pyruvate up to passage 5. Expression of pluripotent and surface marker genes was evaluated at mRNA level. Mesodermal differentiation (adipogenic, osteogenic and chondrogenic) was described. AMSCs expressed mRNA of pluripotent genes Oct4, Nanog, Sox2 and Klf4 and surface markers Cd44, Cd90, Cd105 and MHCII. Fibroblasts showed similar mRNA expression with the exception of Sox2. AMSCs obtained from cougar exhibit multipotency features similar to domestic cats MSC, nevertheless, other analyses are required. AMSCs from cougar could be a source of interest for treatment of individuals that remain in captivity or arrive to wildlife rehabilitation centers.

Mapping DNA interaction landscapes in psoriasis susceptibility loci highlights KLF4 as a target gene in 9q31

BackgroundGenome-wide association studies (GWAS) have uncovered many genetic risk loci for psoriasis, yet many remain uncharacterised in terms of the causal gene and their biological mechanism in disease. This is largely a result of the findings that over 90% of GWAS variants map outside of protein-coding DNA and instead are enriched in cell type- and stimulation-specific gene regulatory regions.ResultsHere, we use a disease-focused Capture Hi-C (CHi-C) experiment to link psoriasis-associated variants with their target genes in psoriasis-relevant cell lines (HaCaT keratinocytes and My-La CD8+ T cells). We confirm previously assigned genes, suggest novel candidates and provide evidence for complexity at psoriasis GWAS loci. For one locus, uniquely, we combine further epigenomic evidence to demonstrate how a psoriasis-associated region forms a functional interaction with the distant (> 500 kb) KLF4 gene. This interaction occurs between the gene and active enhancers in HaCaT cells, but not in My-La cells. We go on to investigate this long-distance interaction further with Cas9 fusion protein-mediated chromatin modification (CRISPR activation) coupled with RNA-seq, demonstrating how activation of the psoriasis-associated enhancer upregulates KLF4 and its downstream targets, relevant to skin cells and apoptosis.ConclusionsThis approach utilises multiple functional genomic techniques to follow up GWAS-associated variants implicating relevant cell types and causal genes in each locus; these are vital next steps for the translation of genetic findings into clinical benefit.

Histone Deacetylase 11 Contributes to Renal Fibrosis by Repressing KLF15 Transcription.

Renal fibrosis represents a key pathophysiological process in patients with chronic kidney diseases (CKD) and is typically associated with a poor prognosis. Renal tubular epithelial cells (RTECs), in response to a host of pro-fibrogenic stimuli, can trans-differentiate into myofibroblast-like cells and produce extracellular matrix proteins to promote renal fibrosis. In the present study we investigated the role of histone deacetylase 11 (HDAC11) in this process and the underlying mechanism. We report that expression levels of HDAC11 were up-regulated in the kidneys in several different animal models of renal fibrosis. HDAC11 was also up-regulated by treatment of Angiotensin II (Ang II) in cultured RTECs. Consistently, pharmaceutical inhibition with a small-molecule inhibitor of HDAC11 (quisinostat) attenuated unilateral ureteral obstruction (UUO) induced renal fibrosis in mice. Similarly, HDAC11 inhibition by quisinostat or HDAC11 depletion by siRNA blocked Ang II induced pro-fibrogenic response in cultured RTECs. Mechanistically, HDAC11 interacted with activator protein 2 (AP-2α) to repress the transcription of Kruppel-like factor 15 (KLF15). In accordance, KLF15 knockdown antagonized the effect of HDAC11 inhibition or depletion and enabled Ang II to promote fibrogenesis in RTECs. Therefore, we data unveil a novel AP-2α-HDAC11-KLF15 axis that contributes to renal fibrosis.

Primary cilia mediate Klf2-dependant Notch activation in regenerating heart

Unlike adult mammalian heart, zebrafish heart has a remarkable capacity to regenerate after injury. Previous study has shown Notch signaling activation in the endocardium is essential for regeneration of the myocardium and this activation is mediated by hemodynamic alteration after injury, however, the molecular mechanism has not been fully explored. In this study we demonstrated that blood flow change could be perceived and transmitted in a primary cilia dependent manner to control the hemodynamic responsive klf2 gene expression and subsequent activation of Notch signaling in the endocardium. First we showed that both homologues of human gene KLF2 in zebrafish, klf2a and klf2b, could respond to hemodynamic alteration and both were required for Notch signaling activation and heart regeneration. Further experiments indicated that the upregulation of klf2 gene expression was mediated by endocardial primary cilia. Overall, our findings reveal a novel aspect of mechanical shear stress signal in activating Notch pathway and regulating cardiac regeneration.

Glucocorticoid Receptor Orchestrates Interactions Between Glucocorticoid ‐Responsive and ‐Unresponsive Enhancers to Modulate Gene Expression

RATIONALEGlucocorticoids (GCs) are stress hormones that act on the GC receptor (GR; NR3C1) to elicit effects, including repression of inflammatory gene expression. The mechanisms by which GR modulate gene expression are not completely understood. GR binds to thousands of genomic loci, but only regulates the expression of hundreds of genes. Genome‐wide chromatin interaction studies revealed that the proximal promotor of various GC‐regulated genes interacts with multiple distal enhancer elements that harbour GC‐dependent GR binding. The significance of such interactions and the contribution of each locus to the achieved gene expression are yet to be investigated. The current work provides a focused perspective on genomic events that lead to the induction of KLF9 by GCs, a gene expression feature that is highly conserved in multiple cell types.RESULTSGC‐mediated induction of KLF9 was confirmed in the airway epithelial cell lines (A549 and BEAS‐2B), as well as in primary culture of various airway structural cells. This induction was abolished in A549 cells either by pretreating cells with the GR antagonist, Org34517, or by knocking down GR with siRNA. Chromatin immunoprecipitation of GR following GC treatment in A549, BEAS‐2B, and primary human bronchial epithelial (HBE) cells showed GR binding to sites 5.9, 6.7, 25, and 65 kb upstream of the KLF9 gene. Global nascent transcript analysis of BEAS‐2B cells following GC treatment showed marked induction of enhancer RNA (eRNA) from each of these sites. This observation was validated using qPCR in A549 and primary HBE cells. GR binding regions were then cloned upstream to a luciferase reporter to test their enhancer activity due to GCs in isolation from their genomic context. There was a clear distinction between proximal regions (i.e. 5.9 and 6.7 kb from KLF9 promotor) and the distal regions (25 and 65 kb) in terms of basal activity and response to GCs. Proximal regions showed very strong basal reporter activity that was not affected by GC treatment. Distal regions, however, showed minimal basal activity but produced dose‐dependent increase in reporter activity by GCs, which was abolished by mutating the GC response elements (GRE) from these regions. Kinetics of long‐range genomic interactions identified a significant interaction between the distal and the proximal regions in a slightly delayed fashion (4h onward), this was temporally associated with enhanced binding of EP300 (histone acetylase associated with gene activation) to the proximal region.CONCLUSIONSOur data suggests that each GR binding site upstream to KLF9 responds differently to GCs, but all sites may collectively contribute to the basal transcriptional activity, induction, and maintenance of KLF9 expression. Co‐localization of other transcriptional regulators may explain the distinction between different sites. Our data are essential in establishing a model to explain GR genomic binding behaviours and how they correlate with gene expression outcomes, thus providing insights on how to modulate GC actions to achieve clinical benefits.Support or Funding InformationFunding: Canadian Institutes of Health Research (CIHR) and Natural Sciences and Engineering Research Council of Canada (NSERC)

KLF2 inhibits TGF-β-mediated cancer cell motility in hepatocellular carcinoma.

Feedback regulation plays a pivotal role in determining the intensity and duration of TGF-β signaling and subsequently affecting the pathophysiological roles of TGF-β, including those in liver malignancy. KLF2, a member of the Krüppel-like factor (KLF) family transcription factors, has been implicated in impeding hepatocellular carcinoma (HCC) development. However, the underlying molecular mechanisms are not fully understood. In the present study, we found that TGF-β stimulates the expression of KLF2 gene in several HCC cell lines. KLF2 protein is able to inhibit TGF-β/Smad signaling in HCC cells as assessed by luciferase reporter assay. Further studies indicated that KLF2 inhibits the transcriptional activity of Smad2/3 and Smad4 and ameliorates TGF-β-induced target gene expression, therefore creating a novel negative feedback loop in TGF-β signaling. Functionally, stably expression of KLF2 in HCCLM3 cells attenuated TGF-β-induced cancer cell motility in wound-healing and transwell assays by interfering with TGF-β-mediated upregulation of MMP2. Together, our results revealed that KLF2 protein has a tumor-suppressive function in HCC through a negative feedback loop over TGF-β signaling.

A potential novel mutation site for type 7 maturity-onset diabetes of the young

Objective To search for the potential novel mutation site and to discuss related clinical characteristics by collecting detailed information and testing the gene of a family with highly suspected type 7 maturity-onset diabetes of the young (MODY7). Methods The gene test was conducted in a 28-year-old female patient with a 20-year course of non-ketosis-prone diabetes, with non-effective long-term insulin treatment, and a 3-generation family history of diabetes, and the patient was found to carry KLF11 gene mutation. Thus, the clinical data of family members were collected and investigated, and the pathogenic gene was tested. Firstly, the proband was searched for pathogenic genes by chip-capture high-throughput sequencing method. Then the mutation sites were verified by Sanger sequencing technology, and other family members were searched for the same mutation sites by the Sanger sequencing technology. Results A total of two members of the family was found to have heterozygous mutation of KLF11 gene: c. 920C>T (No. 920 nucleotide of the coding region mutated from cytosine to thymine), resulting in the change of corresponding amino acid p. P307L (No. 307 amino acid changed from proline to leucine), which was a missense mutation and was consistent with their clinical diagnosis of diabetes. Conclusions The family in this study had a family history of diabetes caused by the missense mutation of KLF11 gene. This is the first report of the mutation site of c. 920C >T (p.P307l), which may be a new mutation site of MODY7. Key words: Maturity-onset diabetes of the young, type 7; Transcription factor KLF11; Missense mutation

Cytoskeletal Protein Zyxin Inhibits the Activity of Genes Responsible for Embryonic Stem Cell Status

Zyxin is a cytoskeletal LIM domain protein that regulates actin cytoskeleton assembly and gene expression. In the present work, we found that Zyxin downregulation in Xenopus laevis embryos reduced the expression of numerous genes regulating cell differentiation but enhanced that of several genes responsible for embryonic stem cell status, specifically klf4, pou5f3.1, pou5f3.2 pou5f3.3 and vent2.1/2. For pou5f3 family genes (mammalian OCT4 orthologs), we showed that this effect was the result of mRNA stabilization due to complex formation with the Y-box protein Ybx1. When bound to Ybx1, Zyxin interfered with the formation of these complexes, thereby stimulating pou5f3 mRNAs degradation. In addition, in zebrafish embryos and human HEK293 cells, Zyxin downregulation increased the mRNA levels of the pluripotency genes KLF4, NANOG and OCT4. Our findings indicate that Zyxin may play a role as a switching hub coupling cell morphogenetic movements, differentiation and the embryonic stem cell status.

MiRNA-20a-5p accelerates the proliferation and invasion of non-small cell lung cancer by targeting and downregulating KLF9.

To uncover the role of microRNA-20a-5p (miRNA-20a-5p) in the progression of Non-small cell lung cancer (NSCLC) and the underlying mechanism. MiRNA-20a-5p level in NSCLC tissues and cell lines was determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Its level in NSCLC patients with larger or smaller tumor size, and either with lymphatic metastasis or not was examined as well. Regulatory effects of miRNA-20a-5p on viability, cell cycle, and invasiveness of A549 and PC9 cells were assessed. The interaction between miRNA-20a-5p and KLF9 was explored by Dual-Luciferase Reporter Gene Assay and Spearman correlation test. At last, the role of miRNA-20a-5p/KLF9 axis in influencing the progression of NSCLC was determined. MiRNA-20a-5p was upregulated in NSCLC tissues and cell lines. Its level was much pronounced in NSCLC patients with larger tumor size or accompanied with lymphatic metastasis. Overexpression of miRNA-20a-5p in A549 cells enhanced viability, cell ratio in S phase, and invasiveness, while the knockdown of miRNA-20a-5p in PC9 cells achieved the opposite trends. KLF9 was confirmed to be the direct target of miRNA-20a-5p. There was a negative correlation between the expression levels of miRNA-20a-5p and KLF9 in NSCLC tissues. In addition, KLF9 overexpression could reverse the promotive effects of upregulated miRNA-20a-5p on the proliferation and invasiveness of A549 cells. On the contrary, the knockdown of KLF9 reversed the inhibitory effects of downregulated miRNA-20a-5p on cellular behaviors of PC9 cells. MiRNA-20a-5p stimulates NSCLC to proliferate and invade by targeting KLF9.

Long noncoding RNA ROR1‑AS1 overexpression predicts poor prognosis and promotes metastasis by activating Wnt/β-catenin/EMT signaling cascade in cervical cancer.

Several long noncoding RNAs (lncRNAs) display functional effects in the tumorigenesis and progression of cervical cancer (CC). We aimed to investigate the roles of lncRNA tyrosine protein kinase transmembrane receptor 1 antisense RNA 1 (ROR1‑AS1) in the development of CC patients. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was performed for the determination of ROR1‑AS1 levels in both CC tissues and cell lines. The clinical value of ROR1‑AS1 expression in CC patients was statistically analyzed. After transfection with si-ROR1‑AS1 in SiHa and HeLa cells, cellular growth and apoptosis were examined by Cell Counting Kit (CCK-8) assay, cell colony formation, and flow cytometry. Then, wound-healing assays and transwell assays were performed to evaluate cell migration and invasion, respectively. The related proteins of epithelial-mesenchymal transition (EMT) markers and Wnt/β-catenin signaling pathway was assessed using Western blot assays. We found that that the expressions of ROR1‑AS1 were distinctly increased in CC tissues and cell lines. Clinical study revealed that high ROR1‑AS1 expression was associated with distant metastasis, FIGO stage, and shorter five-year survival. Functional assays by performing in vitro assays revealed that inhibition of ROR1‑AS1 distinctly suppressed CC cell proliferation, colony formation, migration and invasion, and promoted apoptosis. Based on results of Western blot, we showed that the downregulation of ROR1‑AS1 inhibited the levels of N-cadherin and vimentin. In addition, the distinctly decreased levels of c-myc, β-catenin, and cyclin D1 were observed in CC cells transfected with si-ROR1‑AS1. Our results suggest that ROR1‑AS1 is likely to serve as an efficient therapeutic approach in respect of CC treatment. Our results suggest that KLF5 may be a potential therapeutic target in laryngeal carcinoma.

Targeted Krüppel-Like Factor 4 Gene Knock-Out in Retinal Ganglion Cells Improves Visual Function in Multiple Sclerosis Mouse Model.

Axonal demyelination injury and neuronal degeneration are the primary causes of visual disability in multiple sclerosis (MS)-linked optic neuritis patients. Immunomodulatory therapies targeting inflammation have failed to avert the disease progression and no therapies exist to prevent the neuronal deficits seen in MS to date. Neuroprotective strategies targeting oligodendrocytes and astroglia have shown limited success due to a lack of axonal regeneration from injured neurons. In this study, we used the chronic experimental autoimmune encephalomyelitis (EAE) mouse model of MS to investigate the axonal regenerative approach to improve the neuronal function. Our approach focused on targeted knock-out (KO) of the developmentally regulated axon growth inhibitory Krüppel-like factor 4 (Klf4) gene in retinal ganglion cells (RGCs) of Klf4fl/flmice by intravitreal delivery of AAV2-Cre-ires-EGFP recombinant virus (1) at the time of EAE sensitization and (2) after the onset of optic neuritis-mediated visual defects in the mice. Klf4 gene KO performed simultaneous with EAE sensitization prevented the visual loss as assessed by pattern electroretinograms (PERGs) in the mice and protected the RGCs from EAE-mediated death. More importantly, however, Klf4 gene KO after the onset of optic neuritis also resulted in RGC neuroprotection with additional restoration of their function, thereby improving the visual function outcomes in the EAE model. This study establishes the efficacy of Klf4 targeted knock-down in EAE even after the onset of disease symptoms, and thus should be further explored as a potential treatment strategy for MS/optic neuritis patients.

The saffron effects on expression pattern of critical self-renewal genes in adenocarcinoma tumor cell line (AGS)

Abstracts Background The aim of the current study was to determine the effects of various concentrations of saffron distillate (Crocus sativus) on expression of some self-renewal genes including OCT4, KLF, SOX2, NANOG and Nucleostemin in AGS (gastric adenocarcinoma) cell line. Material and methods The AGS cells were cultured in RPMI1640 medium contained saffron (20, 40 and 100 μg/mL) for 24, 48 and 72 h. Inhibition of cell proliferation was assessed by MTT. The percentage of apoptotic cells was determined by flow cytometry analysis using Annexin V/PI apoptosis detection kit. Total cellular RNA extracted and subjected to and cDNA synthesis and then, the expression of the desired genes was extracted and subjected to in both the control and test groups, using real time- PCR (RT-PCR). Data were analyzed by student t and repeated measure tests. Differences were considered significant if (P Findings There was a significant difference in cell viability, when various concentrations of saffron were used for 24, 48 and 72 h of incubation and apoptosis increased in a time-dependent manner. Flow cytometry results exhibited an obviously significant augmentation in apoptotic AGS cells. Real time- PCR our RT-PCR based findings indicated that saffron distillate has reduced the expression of OCT4, KLF, SOX2, NANOG and Nucleostemin genes in compare to untreated control cells. Conclusion According to the results of this study it may be concluded that saffron distillate can be considered as an inhibitor of cell division and regardingly inhibit cancer progression.

A Krüppel-like factor 1 (KLF1) Mutation Associated with Severe Congenital Dyserythropoietic Anemia Alters Its DNA-Binding Specificity

Krüppel-like factor 1 (KLF1/EKLF) is a transcription factor that globally activates genes involved in erythroid cell development. Various mutations are identified in the human KLF1 gene. The E325K mutation causes congenital dyserythropoietic anemia (CDA) type IV, characterized by severe anemia and non-erythroid-cell-related symptoms. The CDA mutation is in the second zinc finger of KLF1 at a position functionally involved in its interactions with DNA. The molecular parameters of how CDA-KLF1 exerts its biological effects have not been addressed. Here, using an in vitro selection strategy, we determined the preferred DNA-binding site for CDA-KLF1. Binding to the deduced consensus sequence is supported by in vitro gel shifts and by in vivo functional reporter gene studies. Two significant changes compared to wild-type (WT) binding are observed: G is selected as the middle nucleotide, and the 3' portion of the consensus sequence is more degenerate. As a consequence, CDA-KLF1 did not bind the WT consensus sequence. However, activation of ectopic sites is promoted. Continuous activation of WT target genes occurs if they fortuitously contain the novel CDA site nearby. Our findings provide a molecular understanding of how a single mutation in the KLF1 zinc finger exerts effects on erythroid physiology in CDA type IV.

MiR-92a-3p promotes the proliferation and invasion of gastric cancer cells by targeting KLF2.

MicroRNAs (miRNAs) have pivotal roles in the initiation and progression of gastric cancer (GC), and miR-92a-3p has been proved to act as an oncogene in multiple malignancies. However, the molecular mechanisms by which miR-92a-3p contributes to GC remain unclear. The differentially expressed miRNAs were screened by GEO dataset, and the association of miR-92a-3p expression with clinicopathological characteristics and prognosis in patients with GC was analyzed by TCGA dataset. The target genes of miR-92a-3p were identified by bioinformatic analysis, and their interaction was confirmed by luciferase reporter assay. MTT, EdU and Transwell assays were conducted to determine the role of miR-92a-3p in GC cells. As a result, it was found that the expression levels of miR-92a-3p were increased in GC tissues and were associated with tumor size, lymph node infiltration and distant metastasis, acting as an independent prognostic factor of poor survival in patients with GC. Restored expression of miR-92a-3p facilitated cell proliferation, DNA synthesis and cell invasion, but its inhibitor reversed these effects. KLF2 was further identified as a direct target of miR-92a-3p, indicating a negative correlation with miR-92a-3p expression and harboring a favorable prognosis in GC. In addition, KLF2 repressed cell proliferation and invasion and attenuated the tumor-promoting effects of miR-92a-3p in GC cells. Altogether, our findings demonstrated that miR-92a-3p promoted the proliferation and invasion of GC cells by targeting KLF2.

The potential role of Krüppel-like factor 13 (Aj-klf13) in the intestine regeneration of sea cucumber Apostichopus japonicus

Krüppel-like factor13 (klf13), a member of the Krüppel-like factor family, plays a vital role in cell proliferation and differentiation. When sea cucumber Apostichopus japonicus is attacted by predators, it can spit viscera in order to escape attack, and then complete the intestine regeneration process within 15 days. However, the potential role of klf13 from A. japonicus (Aj-klf13) in the intestine regeneration of sea cucumber A. japonicus still remains unknown. In present paper, the full-length cDNA of klf13 gene from A. japonicus was cloned by RACE techniques, and it was composed of 2496 bp, including a 245 bp 5′ UTR, a 1396 bp 3′ UTR and a 855 bp open reading frame, which encoded a polypeptide of 284 amino acids and C2H2 zinc finger domains. The expression level of Aj-klf13 showed an increasing trend in intestine regeneration process of sea cucumber, and it reached the highest at 6 days, returning to the normal at 15 days. By western blot, the expression level of Aj-KLF13 protein was basically consistent with that of Aj-klf13 gene. The expression locations of protein by immunofluorescence indicated that Aj-KLF13 was widely expressed in the normal physiological state and intestine regeneration process of sea cucumbers, which was in the nucleus. There was tissue specificity of the protein, which was mainly distributed in luminal epithelium and coelomic epithelium. These results indicate that Aj-klf13 plays a crucial role in the intestine regeneration process of sea cucumber A. japonicus.

Sphere-induced reprogramming of RPE cells into dual-potential RPE stem-like cells.

BackgroundThe retinal pigment epithelium (RPE) has the potential to regenerate the entire neuroretina upon retinal injury in amphibians. In contrast, this regenerative capacity has been lost in mammals. The reprogramming of differentiated somatic cells into induced pluripotent stem cells (iPSCs) by viral transduction of exogenous stem cell factors has triggered a revolution in regenerative medicine. However, the risks of potential mutation(s) caused by random viral vector insertion in host genomes and tumor formation in recipients hamper its clinical application. One alternative is to immortalize adult stem cells with limited potential or to partially reprogram differentiated somatic cells into progenitor-like cells through non-integration protocols.MethodsSphere-induced RPE stem cells (iRPESCs) were generated from adult mouse RPE cells. Their stem cell functionality was studied in a mouse model of retinal degeneration. The molecular mechanism underlying the sphere-induced reprogramming was investigated using microarray and loss-of-function approaches.FindingsWe provide evidence that our sphere-induced reprogramming protocol can immortalize and transform mouse RPE cells into iRPESCs with dual potential to differentiate into cells that express either RPE or photoreceptor markers both in vitro and in vivo. When subretinally transplanted into mice with retinal degeneration, iRPESCs can integrate to the RPE and neuroretina, thereby delaying retinal degeneration in the model animals. Our molecular analyses indicate that the Hippo signaling pathway is important in iRPESC reprogramming.InterpretationThe Hippo factor Yap1 is activated in the nuclei of cells at the borders of spheres. The factors Zeb1 and P300 downstream of the Hippo pathway are shown to bind to the promoters of the stemness genes Oct4, Klf4 and Sox2, thereby likely transactivate them to reprogram RPE cells into iRPESCs.FundNational Natural Science Foundation of China and the National Institute of Health USA.

A Special Amino-Acid Formula Tailored to Boosting Cell Respiration Prevents Mitochondrial Dysfunction and Oxidative Stress Caused by Doxorubicin in Mouse Cardiomyocytes.

Anthracycline anticancer drugs, such as doxorubicin (DOX), can induce cardiotoxicity supposed to be related to mitochondrial damage. We have recently demonstrated that a branched-chain amino acid (BCAA)-enriched mixture (BCAAem), supplemented with drinking water to middle-aged mice, was able to promote mitochondrial biogenesis in cardiac and skeletal muscle. To maximally favor and increase oxidative metabolism and mitochondrial function, here we tested a new original formula, composed of essential amino acids, tricarboxylic acid cycle precursors and co-factors (named α5), in HL-1 cardiomyocytes and mice treated with DOX. We measured mitochondrial biogenesis, oxidative stress, and BCAA catabolic pathway. Moreover, the molecular relevance of endothelial nitric oxide synthase (eNOS) and mechanistic/mammalian target of rapamycin complex 1 (mTORC1) was studied in both cardiac tissue and HL-1 cardiomyocytes. Finally, the role of Krüppel-like factor 15 (KLF15), a critical transcriptional regulator of BCAA oxidation and eNOS-mTORC1 signal, was investigated. Our results demonstrate that the α5 mixture prevents the DOX-dependent mitochondrial damage and oxidative stress better than the previous BCAAem, implying a KLF15/eNOS/mTORC1 signaling axis. These results could be relevant for the prevention of cardiotoxicity in the DOX-treated patients.