Project description:Krüppel-like factors (Klfs) are DNA-binding transcriptional factors that regulate multiple physiological features, including the cell cycle, cell differentiation and tissue organization. Klf2, Klf4 and Klf5 are crucial for maintenance of pluripotent and somatic stem cells. We show that Klf2, Klf4 and Klf5 genes are required for normal neural development in a redundant manner and depletion of all three genes in neural precursor cells results in impaired activation of Notch signaling and early lethality. Klf5 plays a dominant role in maintenance of neural precursor cell populations by suppressing their differentiation and radial migration in developing mammalian brain. Klf4 and Klf5 also regulate proliferation of neural precursor cells in an opposing fashion. Klf4 promotes generation of quiescent neural stem cells, whereas Klf5 supports vigorously dividing intermediate progenitor cells. Our findings provide insight into mechanisms by which neural precursor cells provide large numbers of differentiating cells and a few quiescent neural stem cells.
Project description:Homozygous disruption of Bteb2/Klf5, a homolog of Drosophila gap gene Krüppel, led to increased expression of various differentiation marker genes, such as Fgf5, Cdx2, and Brachyury in mouse ES cells without compromising their ability to differentiate into all three germ layers. Upon removal of LIF, Klf5-deficient ES cells showed faster differentiation kinetics than wild-type ES cells. In contrast, overexpression of Klf5 in ES cells suppressed the transcription of differentiation marker genes, and maintained pluripotency in the absence of LIF. In order to search downstream genes of Klf5, we surveyed genes implicated in ES cell proliferation by microarray analysis Keywords: cell type comparison
Project description:Klf5 has essential functions during early embryogenesis and in the derivation of ES cells from inner-cell mass of blastocyst. Among Kruppel-like factor (Klf) family members, only Klf5 shows peri-implantation lethal phenotype, but the precise mechanisms still remain unknown. To understand and identify molecular mechanisms, we performed microarray analysis by using E3.0 WT and Klf5 KO embryos when first phenotype of Klf5 deficiency appears.
Project description:Activation of the Ras/Erk pathway upregulates expression of the Kruppel-like Factor 5 (KLF5) transcription factor, and KLF5 is a downstream mediator of Ras oncogenic signaling. Specifically, in bladder and colon cancer cell lines KLF5 upregulates the Ras-pathway target gene cyclin D1, and facilitates entry into the S phase of the cell cycle. Ras mutations are common in lung cancer, but a role for KLF5 in lung tumorigenesis has not been defined. To this end, we manipulated KLF5 expression in four Ras-mutant human lung adenocarcinoma cell lines to find that KLF5 significantly modulates anchorage-independent growth, a mutant Ras phenotype. However, in a mouse model of human lung adenocarcinoma, K-RasG12D does not critically require Klf5 to mediate oncogenesis or induce cyclin D1 expression. Patients with lung tumors expressing high levels of KLF5 have significantly better prognosis than those with low or no KLF5 expression (opposite of mutant Ras prognosis). The latter may be explained by KLF5 transcriptional repression of the ATP-binding cassette, sub-family G (WHITE), member 2 (ABCG2), an anthracycline transporter. In agreement with this, KLF5 knockdown cells display significantly more Hoechst â??side populationâ?? and resistance to doxorubicin. In summary, while KLF5 is not an obligate partner in Ras oncogenic signaling, KLF5 control of ABCG2 expression is significant to patient survival. Experiment Overall Design: Total RNA was extracted from H441 cells transduced with KLF5-specific shRNA (KD), KLF5 over expression (OE) and MSCV empty vertor (NT) respectively. The cRNAs was then hybridized to Human Genome U133 Plus 2.0 Arrays (Affymetrix) according to manufacturerâ??s protocol.
Project description:Activation of the Ras/Erk pathway upregulates expression of the Kruppel-like Factor 5 (KLF5) transcription factor, and KLF5 is a downstream mediator of Ras oncogenic signaling. Specifically, in bladder and colon cancer cell lines KLF5 upregulates the Ras-pathway target gene cyclin D1, and facilitates entry into the S phase of the cell cycle. Ras mutations are common in lung cancer, but a role for KLF5 in lung tumorigenesis has not been defined. To this end, we manipulated KLF5 expression in four Ras-mutant human lung adenocarcinoma cell lines to find that KLF5 significantly modulates anchorage-independent growth, a mutant Ras phenotype. However, in a mouse model of human lung adenocarcinoma, K-RasG12D does not critically require Klf5 to mediate oncogenesis or induce cyclin D1 expression. Patients with lung tumors expressing high levels of KLF5 have significantly better prognosis than those with low or no KLF5 expression (opposite of mutant Ras prognosis). The latter may be explained by KLF5 transcriptional repression of the ATP-binding cassette, sub-family G (WHITE), member 2 (ABCG2), an anthracycline transporter. In agreement with this, KLF5 knockdown cells display significantly more Hoechst “side population” and resistance to doxorubicin. In summary, while KLF5 is not an obligate partner in Ras oncogenic signaling, KLF5 control of ABCG2 expression is significant to patient survival.
Project description:Three transcription factors KLF5, GATA4 and GATA6 are recurrently amplified in multiple gastric cancer cohorts, representing one type of lineage-survival oncogenes in gastric cancer. ChIP-Seq analysis of these three factors in multiple cell lines revealed that significant number of genomic sites are co-occupied by KLF5 and GATA4 and/or GATA6. Integrative analysis of ChIP-Seq and gene expression identified several targets of the three transcription factors in both cell lines and primary tumors, including HNF4A. These results suggest that KLF5, GATA4 and GATA6 interact and co-operate to regulate HNF4A and other genes to promote tumorigenesis in gastric cancer. ChIP-Seq experiments of KLF5, GATA4 and GATA6 were performed in three gastric cancer cell lines YCC3, AGS and KATOIII
Project description:KLF5 is a basic transcription factor that regulates multiple biological processes, but its function in tumorigenesis appears contradictory in the current literature, with some studies showing tumor suppressor activity and others showing tumor promoting activity. In this study, we examined the function of Klf5 in prostatic tumorigenesis using mice with prostate specific deletion of Klf5 and Pten, both of which are frequently deleted in human prostate cancer. Histological and molecular analyses demonstrated that when one Pten allele was deleted, which causes mouse intraepithelial neoplasia (mPIN), Klf5 deletion accelerated the emergence and progression of mPIN. When both Pten alleles were deleted, which causes prostate cancer, Klf5 deletion promoted tumor growth and caused more severe morphological and molecular alterations, and homozygous deletion of Klf5 was more effective than hemizygous deletion. Unexpectedly, while Klf5 deletion clearly promoted tumorigenesis in luminal cells, it actually diminished the numbers of Ck5-positive basal cells in the Pten-null tumors. Klf5 deletion also increased the cell proliferation rate in tumors with Pten deletion, which involved extensive activation of the PI3K/AKT and MAPK mitogenic signaling pathways and inactivation of the p15 cell cycle inhibitor. Global gene expression and pathway analyses demonstrated that multiple mechanisms could be responsible for the tumor promoting effect of Klf5 deletion, We used microarrays to detail the global programme of gene expression of Klf5-wildtype and Klf5-null mouse dorsal prostates under Pten-null context to figure out the differential expression profiling underlying tumorigenesis 4 Klf5-wildtype and 4 Klf5-null mouse (6 months age) dorsal prostates under Pten-null context were used for RNA extraction and hybridization on Affymetrix mouse st 1.0 array