Member Of Kruppel-like Factor Family Research Articles

Genome-Wide Identification, Evolution, and miRNA-22 Regulation of Kruppel-Like Factor (KLF) Gene Family in Chicken (Gallus gallus).

Krüppel-like factors (KLFs) are a class of fundamental transcription factors that are widely present in various eukaryotes from nematodes to humans, named after their DNA binding domain which is highly homologous to the Krüppel factor in fruit flies. To investigate the composition, organization, and evolutionary trajectory of KLF gene family members in chickens, in our study, we leveraged conserved sequences of KLF genes from representative classes across fish, amphibians, birds, and mammals as foundational sequences. Bioinformatic tools were employed to perform homology alignment on the chicken genome database, ultimately identifying the KLF family members present in chickens. The gene structure, phylogenetic analysis, conserved base sequences, physicochemical properties, collinearity analysis, and protein structure were then analyzed using bioinformatic tools. Additionally, the impact of miRNA-22, related to poultry lipid metabolism, on the expression of the KLF gene family in the liver, heart, and muscle of Qingyuan partridge chickens was explored. The results showed that: (1) compared to fish, the KLF family in birds is more closely related to mammals and amphibians; (2) KLFs within the same subgroups are likely to be derived from a common ancestral gene duplication; (3) KLF3/8/12 in the same subgroup may have some similar or overlapping functions; (4) the motif 4 of KLF5 was most likely lost during evolution; (5) KLF9 may perform a similar function in chickens and pigs; (6) there are collinear relationships between certain KLF genes, indicating that there are related biomolecular functions between these KLF genes; (7) all members of the KLF family in chickens are non-transmembrane proteins; and (8) interference and overexpression of miRNA-22 in Qingyuan partridge chickens can affect the expression levels of KLF genes in liver, heart, and muscle.

Characterization of Kruppel-like factor 6 in Epinephelus coioides: The role in viral infection and the transcriptional regulation on Peroxisome proliferator-activated receptor δ

The Kruppel-like factor 6 (KLF6) is a member of Kruppel-like factor family, which belong to the Zinc finger family of transcription factors that mediates various cellular processes, such as proliferation, differentiation, development, and programmed cell death. Peroxisome proliferator-activated receptors (PPARs) are a family of transcription factors belonging to the nuclear receptor superfamily and they regulate numerous genes through ligand-dependent transcriptional activation and repression. In this study, we focus on the role of KLF6 gene in virus infection and the regulation of KLF6 on PPAR-δ in orange-spotted grouper (Epinephelus coioides). The ORF sequence of EcKLF6 was 846 bp, encoding a polypeptide of 282 amino acids with three conserved Zinc finger (type Cys2-His2) domain in the C-terminal region. Basing on the detection of the mRNA levels of viral genes, western blotting of MCP protein, and morphological CPEs, we found that the overexpression of EcKLF6 suppressed the replication of Singapore grouper iridovirus (SGIV), exerting its antiviral activity against fish virus. Moreover, promoter analysis was performed to investigate whether EcKLF6 was a regulator of EcPPAR-δ. The luciferase reporter assay and real time PCR results indicated a negative regulatory role of EcKLF6 on EcPPAR-δ transcription in grouper. Further experimental analysis shows that the potential EcKLF6 binding sites may locate in the EcPPAR-δ-4-M3 (+133 to +154) and EcPPAR-δ-4-M4 (+354 to +368) region of the EcPPAR-δ promoter. Electrophoretic mobile shift assays (EMSAs) verified that EcKLF6 interacted with the binding site of the EcPPAR-δ-4-M4 promoter region. In addition, we also found that KLF6 promotes inflammatory responses in GS cells. Considering that KLF6 and PPAR-δ play opposite roles in regulating inflammatory responses, we speculated the promoting effect of KLF6 on inflammatory response may be related to its negative regulation on EcPPAR-δ. In conclusion, the present study provides the first evidence of the negative regulation of EcPPAR-δ transcription by EcKLF6 and contributes to a better understanding of the transcriptional mechanisms of EcKLF6 in fish.

KLF15 regulates in vitro chondrogenic differentiation of human mesenchymal stem cells by targeting SOX9

Mesenchymal stem cells (MSCs) are multipotent stromal cells residing in the bone marrow. MSCs have the potential to differentiate into adipocytes, chondrocytes, and other types of cells. However, the mechanism underlying MSC differentiation is still not fully understood. Here we aimed to investigate the function of the Kruppel-like factor (KLF) transcriptional factor family in regulating chondrogenic differentiation from human MSCs. Among the KLF family members, KLF15 was activated during different models of chondrogenic differentiation in a time-dependent manner. Lentivirus-mediated knockdown of KLF15 in MSCs repressed chondrogenic differentiation whereas KLF15 overexpression facilitated chondrogenic differentiation. KLF15 promoted the chondrogenic differentiation of human MSCs by activating the expression of SOX9, which is critically involved in KLF15 function during chondrogenic differentiation. Our mechanism study demonstrated that KLF15 bound the promoter of SOX9 and promoted the activation of the SOX9 promoter. Taken together, our findings show that KLF15 promotes chondrogenic differentiation of human MSCs by activating SOX9.

KLF2 is downregulated in pancreatic ductal adenocarcinoma and inhibits the growth and migration of cancer cells.

Members of the Kruppel-like factor (KLF) family have been considered as the tumor suppressors for their inhibitory effects on cell proliferation. Dysregulation of KLF2, a member of KLF family, has been observed in various cancer types. However, its expression pattern and functions in the pancreatic ductal adenocarcinoma (PDAC) are unknown. In this study, we examined the expression of KLF2 in PDAC clinical samples and evaluated the functions of KLF2 in the progression of PDAC. KLF2 is shown to be downregulated in PDAC clinical samples and overexpression of KLF2 inhibits the growth, migration, and metastasis of PDAC cancer cells. KLF2 interacts with beta-catenin and negatively regulates the beta-catenin/TCF signaling. Taken together, this study suggests the suppressive functions of KLF2 in PDAC.

Kruppel Like Factor 7 Suppresses Hematopoietic Stem and Progenitor Cell Function

Abstract 2356Kruppel like factor 7 (KLF7) expression is an independent predictor of poor outcome in pediatric acute lymphoblastic leukemia (Flotho, et al; Blood 2007). In addition, KLF7 overexpression is associated with Imatinib-resistant CML (Cammarata, et al; Clinical Leukemia 2007). The kruppel like factor (KLF) family of transcription factors are involved in regulating cellular growth and differentiation in multiple tissue types. KLF7 is important for neurogenesis, and mice lacking KLF7 die perinatally with severe neurologic defects (Laub, et al; Mol Cell Biol 2005). While no specific role for KLF7 in hematopoiesis has been previously reported, loss of the closely related family member KLF6 is associated with defective blood cell production (Matsumoto, et al; Blood 2006), and other KLF family members are involved in multiple aspects of hematopoiesis. Targets of KLF7 include known regulators of hematopoietic stem and progenitor cell (HSPC) function including TRKA, Cebp/a, and CDKN1A (p21). Normal HSPCs appear to have a low level of KLF7 expression based on RNA expression profiling of populations enriched for these cells. Given these findings, we hypothesized that KLF7 may play a role in regulating normal HSPC function, and may contribute to leukemogenesis or resistance to therapy. To test this hypothesis, we first analyzed the effect of the loss of KLF7 on hematopoiesis. Specifically, we generated Klf7−/− fetal liver chimeras and characterized their hematopoiesis. Long-term multilineage engraftment of Klf7−/− cells was comparable to control cells. Moreover, HSC self-renewal, as assessed by serial transplantation was not effected by the loss of KLF7. To model the effect of KLF7 overexpression on HSPC function, we generated retroviral and lentiviral vectors that express KLF7. KLF7 expression in wild type bone marrow cells transduced with KLF7 retrovirus was increased approximately 10-fold. Overexpression of KLF7 was associated with a marked suppression of myeloid progenitor cell growth, as assessed using colony-forming cell assays. Relative to the initial transduction efficiency, the number of myeloid colonies produced from KLF7-transduced cells compared to vector-alone transduced cells was reduced 5.7 ± 1.9 fold. We next assessed short- and long-term engraftment of KLF7-transduced cells by bone marrow transplantation. In experiments using bone marrow cells transduced with high efficiency (≥ 60% transduced cells), overexpression of KLF7 resulted in impaired radioprotection. Whereas all (12 of 12) recipients transplanted with control transduced cells survived, only 42% (5 out of 12) of recipients of KLF7 transduced cells survived more than two weeks after transplantation (P < 0.003). When these experiments were performed with a reduced multiplicity of infection to achieve a lower transduction efficiency, all recipient mice survived at least 3 months. Whereas control-transduced cells were readily detected at near input levels (on average, 40% of nucleated blood cells), minimal contribution of KLF7-transduced cells was observed in all lineages except T cells. Interestingly, KLF7-transduced T cells were present at near input levels. In summary, our show that KLF7 is not required for normal HSPC function. However, overexpression of KLF7 leads to a marked suppression of the short- and long-term repopulating activity of HSPC with the exception cells in the T cell lineage. Whether KLF7 expression contributes to T cell leukemogenesis through suppression of other hematopoietic lineages will require further study. Disclosures:No relevant conflicts of interest to declare.

Dynamic transcription programs during ES cell differentiation towards mesoderm in serum versus serum-freeBMP4 culture

BackgroundExpression profiling of embryonic stem (ES) cell differentiation in the presence of serum has been performed previously. It remains unclear if transcriptional activation is dependent on complex growth factor mixtures in serum or whether this process is intrinsic to ES cells once the stem cell program has been inactivated. The aims of this study were to determine the transcriptional programs associated with the stem cell state and to characterize mesoderm differentiation between serum and serum-free culture.ResultsES cells were differentiated as embryoid bodies in 10% FBS or serum-free media containing BMP4 (2 ng/ml), and expression profiled using 47 K Illumina(R) Sentrix arrays. Statistical methods were employed to define gene sets characteristic of stem cell, epiblast and primitive streak programs. Although the initial differentiation profile was similar between the two culture conditions, cardiac gene expression was inhibited in serum whereas blood gene expression was enhanced. Also, expression of many members of the Kruppel-like factor (KLF) family of transcription factors changed dramatically during the first few days of differentiation. KLF2 and KLF4 co-localized with OCT4 in a sub-nuclear compartment of ES cells, dynamic changes in KLF-DNA binding activities occurred upon differentiation, and strong bio-informatic evidence for direct regulation of many stem cell genes by KLFs was found.ConclusionDown regulation of stem cell genes and activation of epiblast/primitive streak genes is similar in serum and defined media, but subsequent mesoderm differentiation is strongly influenced by the composition of the media. In addition, KLF family members are likely to be important regulators of many stem cell genes.

Kruppel-Like Factor 4 Upregulates p21 and Downregulates Proliferation of Human and Mouse HSPCs, but Is Not Essential for Mouse HSPC Repopulation.

Several Kruppel-like factor family members, including KLF1, KLF2, KLF3, and KLF6 have pivotal roles in hematopoiesis. Experiments in zebrafish have suggested that KLF4 may play a similar role. Here we found that enforced expression of KLF4 in hematopoietic cells induced cell cycle arrest without triggering apoptosis. Based on the high levels of expression of KLF4 in mouse and human hematopoietic stem-progenitor cells (HSPCs), we hypothesized and demonstrated that KLF4 regulates proliferation of these cells through regulation of p21cip1/waf1 (p21). Nevertheless, KLF4−/− mouse fetal liver cells had normal numbers of all mature lineages and provided radioprotection, similar to wild type (wt) controls. Furthermore, in long-term competitive repopulation assays, KLF4−/− mouse HSPCs demonstrated hematopoietic potency equivalent to wt. We found that KLF2 is expressed at higher levels than KLF4 in mouse HSPCs and is a more potent activator of p21, suggesting that KLF2 (and/or other KLF family members) may play a compensatory role in KLF4−/− HSPCs. Thus, although is not essential for their normal development and function, KLF4 expression is sufficient to induce p21-mediated cell cycle arrest in hematopoietic cells.