GATA-1 and GATA-2 binding to 3' enhancer of WT1 gene is essential for its transcription in acute leukemia and solid tumor cell lines

Transgenic Mouse Models to Study the Development and Maintenance of the Adrenal Cortex

The cortex of the adrenal gland is organized into concentric zones that produce distinct steroid hormones essential for body homeostasis in mammals. Mechanisms leading to the development, zonation and maintenance of the adrenal cortex are complex and have been studied since the 1800s. However, the advent of genetic manipulation and transgenic mouse models over the past 30 years has revolutionized our understanding of these mechanisms. This review lists and details the distinct Cre recombinase mouse strains available to study the adrenal cortex, and the remarkable progress total and conditional knockout mouse models have enabled us to make in our understanding of the molecular mechanisms regulating the development and maintenance of the adrenal cortex.

Differential expression profiling of onco and tumor-suppressor genes from major-signaling pathways in Wilms' tumor

PURPOSE

Wilms' tumor is the most-frequent malignant-kidney tumor in children under 3-4 years of age and is caused by genetic alterations of oncogenes (OG) and tumor-suppressor genes (TG). Wilms' tumor has been linked to many OG-&-TG. However, only WT1 has a proven role in the development of this embryonic-tumor.

METHODS

The study investigates the level of mRNA expression of 16 OGs and 20 TGs involved in key-signaling pathways, including chromatin modification; RAS; APC; Cell Cycle/Apoptosis; Transcriptional Regulation; PI3K; NOTCH-&-HH; PI3K & RAS of 24-fresh Wilms'-tumor cases by capture-and-reporter probe Code-Sets chemistry, as CNVs in these pathway genes have been reported.

RESULTS

Upon extensively investigating, MEN1, MLL2, MLL3, PBRM1, PRDM1, SMARCB1, SETD2, WT1, PTPN11, KRAS, HRAS, NF1, APC, RB1, FUBP1, BCOR, U2AF1, PIK3CA, PTEN, EBXW7, SMO, ALK, CBL, EP300-and-GATA1 were found to be significantly up-regulated in 58.34, 62.5, 79.17, 91.67, 58, 66.66,54, 58.34, 66.67, 75, 62.5, 62.5, 58, 79.17, 79.17, 75, 70.84, 50, 50, 75, 66.66, 62.50, 61.66, 58.34-and-62.50% of cases respectively, whereas BRAF, NF2, CDH1, BCL2, FGFR3, ERBB2, MET, RET, EGFR-and-GATA2 were significantly down regulated in 58, 87.50, 79.16, 54.16, 79.17, 91.66, 66.66, 58.33, 91.66-and-62.50% of cases, respectively. Interestingly, the WT1 gene was five-fold down regulated in 41.66% of cases only.

CONCLUSION

Hence, extensive profiling of OGs and TGs association of major-signaling pathways in Wilms' tumor cases may aid in disease diagnosis. PBRM1 (up-regulated in 91.67% of cases), ERBB2 and EGFR (down-regulated in 91.66 and 91.66% of cases, respectively) could be marker genes. However, validation of all relevant results in a larger number of samples is required.

Androgen promotes differentiation of PLZF+ spermatogonia pool via indirect regulatory pattern

Background

Androgen plays a pivotal role in spermatogenesis, accompanying a question how androgen acts on germ cells in testis since germ cells lack of androgen receptors (AR). Promyelocytic leukemia zinc-finger (PLZF) is essential for maintenance of undifferentiated spermatogonia population which is terminologically called spermatogonia progenitor cells (SPCs).

Aims

We aim to figure out the molecular connections between androgen and fates of PLZF⁺ SPCs population.

Method

Immunohistochemistry was conducted to confirm that postnatal testicular germ cells lacked endogenous AR. Subsequently, total cells were isolated from 5 dpp (day post partum) mouse testes, and dihydrotestosterone (DHT) and/or bicalutamide treatment manifested that Plzf was indirectly regulated by androgen. Then, Sertoli cells were purified to screen downstream targets of AR using ChIP-seq, and gene silence and overexpression were used to attest these interactions in Sertoli cells or SPCs-Sertoli cells co-culture system. Finally, these connections were further verified in vivo using androgen pharmacological deprivation mouse model.

Results

Gata2 is identified as a target of AR, and β1-integrin is a target of Wilms’ tumor 1 (WT1) in Sertoli cells. Androgen signal negatively regulate β1-integrin on Sertoli cells via Gata2 and WT1, and β1-integrin on Sertoli cells interacts with E-cadherin on SPCs to regulate SPCs fates.

Conclusion

Androgen promotes differentiation of PLZF⁺ spermatogonia pool via indirect regulatory pattern.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0369-8) contains supplementary material, which is available to authorized users.

The clinical significance of the alternative Wilms tumor gene overexpression-hypermethylation signature in acute myeloid leukemia

BACKGROUND

Wilms tumor 1 (WT1) gene is overexpressed in numerous cancers, including acute myeloid leukemia (AML). The alternative WT1 gene (AWT1) is generated from alternative transcription start site in the WT1 first intron and encodes an N-terminal-truncated protein lacking the repressor domain. Although WT1 overexpression is a common feature in AML, the expression levels of the AWT1 and its underlying epigenetic alterations, as well as their clinical relevance in AML remain unknown.

METHODS

Quantitative assessment of AWT1 gene transcripts was performed using real-time polymerase chain reaction (PCR). Bisulfite PCR followed by pyrosequencing was done to determine the methylation status of the AWT1 promoter. The bone marrow samples were collected at diagnosis and after completion of induction chemotherapy from 80 newly diagnosed AML patients. Forty non-malignant BM samples were recruited as controls.

RESULTS

The AWT1 was significantly overexpressed in AML patients. Robust hypermethylation of the AWT1 promoter was found to be a highly specific and sensitive marker for AML (p < 0.001). Significant positive correlations between the AWT1 expression and methylation levels with BM blast counts at both initial diagnosis and after induction therapy were observed (p < 0.001). AWT1 overexpression at the initial diagnosis of AML was found to be an independent negative factor for complete remission response after induction therapy (p = 0.014).

CONCLUSION

The AWT1 gene overexpression-hypermethylation signature is a characteristic marker that positively correlates with the leukemic burden in AML. AWT1 overexpression at AML diagnosis is an independent negative predictor for CR after induction chemotherapy.

GATA2 Inhibition Sensitizes Acute Myeloid Leukemia Cells to Chemotherapy

Drug resistance constitutes one of the main obstacles for clinical recovery of acute myeloid leukemia (AML) patients. Therefore, the treatment of AML requires new strategies, such as adding a third drug. To address whether GATA2 could act as a regulator of chemotherapy resistance in human leukemia cells, we observed KG1a cells and clinical patients’ AML cells with a classic drug (Cerubidine) and Gefitinib. After utilizing chemotherapy, the expression of GATA2 and its target genes (EVI, SCL and WT1) in surviving AML cells and KG1a cells were significantly enhanced to double and quadrupled compared to its original level respectively. Furthermore, with continuous chemotherapeutics, AML cells with GATA2 knockdown or treated with GATA2 inhibitor (K1747) almost eliminated with dramatically reduced expression of WT1, SCL, EVI, and significantly increased apoptotic population. Therefore, we propose that reducing GATA2 expression or inhibition of its transcription activity can relieve the drug resistance of acute myeloid leukemia cells and it would be helpful for eliminating the leukemia cells in patients.

Mechanism of paclitaxel resistance in a human prostate cancer cell line, PC3-PR, and its sensitization by cabazitaxel

Paclitaxel (PTX) is a microtubule-targeting drug widely used for the treatment of a variety of cancers. However, drug resistance can emerge after a series of treatments, and this can seriously affect the patient's prognosis. Here, we analyzed the mechanism of PTX resistance using a human prostate cancer cell line, PC3, and its PTX-resistant subline, PC3-PR. Compared with PC3, PC3-PR exhibited some unique phenotypes that might be associated with PTX resistance, including decreased expression of acetylated α-tubulin and the cell cycle regulator p21, and increased expression of βIII tubulin, histone deacetylase 6 (HDAC6), and the anti-apoptotic protein Bcl2. The drug exporters MDR1 and MRP1 were not involved in PTX resistance. Although cabazitaxel (CTX), a novel taxoid, has been reported to overcome PTX resistance, its mechanism of action is unknown. We found that treatment of PC3-PR cells with CTX induced expression of acetylated α-tubulin and p21, but not the related regulators p27, p15, and p16 or the Bcl2 family proteins. The pan-HDAC inhibitors trichostatin A and suberanilohydroxamic acid and the HDAC6-specific inhibitor tubacin inhibited PC3-PR proliferation and increased expression of p21 and acetylated α-tubulin in a manner similar to CTX. Our data shed light on the cellular response to PTX and CTX.

The Wilms Tumor-1 (WT1) rs2234593 variant is a prognostic factor in normal karyotype acute myeloid leukemia

The single-nucleotide polymorphism (SNP) within Wilms tumor-1 (WT1) exon 7, rs16754, has been arguably reported to be implicated in acute myeloid leukemia (AML) prognosis. We assessed the potential association of selected WT1 SNPs as well as WT1 mutations in normal karyotype (NK)-AML and evaluated the prognostic value of these normal gene variants. Diagnostic samples from a series of 474 young adult NK-AML patients were used to genotype five WT1 SNPs using TaqMan assays and to directly sequence WT1 exons 7 and 9. Analysis of five WT1 gene variants showed an association of rs2234593 allele C with WT1 Ex7 mutation. Prognostic study of the same variants identified rs2234593 significantly associated with relapse and overall survival (OS). Patients with rs2234593AA/AC showed significantly higher 10-year OS (50 vs 36 %, hazard ratio (HR) = 0.69 (0.52–0.90), p = 0.006) and lower cumulative incidence of relapse (CIR) (36 vs 51 %, HR = 0.62 (0.45–0.86), p = 0.004) compared to those with rs2234593CC. The effect of AA genotype on CIR remained significant after adjustment for basic covariates including FLT3 internal-tandem duplication (FLT3-ITD) and nucleophosmin 1 (NPM1) mutations (HR = 0.60 (0.41–0.89), p = 0.009), with some evidence of improved survival (HR = 0.75 (0.55–1.03), p = 0.07). A multivariate analysis showed WT1 Ex7-mutant as the major relapse predictor, with a tendency for rs2234593-A effect after allowing for Ex7 mutation (p = 0.07). No adjusted risk benefit was found for previously reported rs16754-G. In conclusion, WT1 normal gene variant rs2234593 is associated with mutational status of WT1 Ex7 and is a further prognostic marker independent from FLT3-ITD and NPM1 mutations in NK-AML.

Age-associated methylation change of TAP1 promoter in piglet

Diarrhea and edematous disease are two major causes of mortality in postweaning piglets. These conditions lead to huge economic losses in the swine industry. Escherichia coli F18 is the primary causative agent of these two diseases. Transported associated with antigen processing (TAP) plays an important role in the immune response and the TAP1 gene could be an effective anti-E. coli F18 molecular marker in pigs. The aim of this study was to determine the correlation between TAP1 gene promoter CpG island methylation status and mRNA expression in piglets. In this study, bisulfite sequencing PCR (BSP) was used to detect the methylation status of the TAP1 gene promoter CpG islands and fluorescence quantitative PCR was used to detect TAP1 expression in the jejunum of Sutai piglets from birth to weaning age. The fragment of the TAP1 gene promoter region under investigation has no mutation, has 13 putative transcription factor binding sites containing 19 CpG sites, and may be important for regulation of gene expression. With increasing age, the overall methylation levels decreased, while the TAP1 expression levels increased, indicating a negative correlation between TAP1 expression and promoter methylation levels. Variance analysis showed significant differences in the methylation status of CpG_4, CpG_13 and CpG_15 among the different age groups (P<0.05). Our data indicate that TAP1 expression is increased by demethylation of promoter CpG islands, with CpG_4, CpG_13 and CpG_15 implicated as the critical regulatory sites.

Full-length soluble urokinase plasminogen activator receptor down-modulates nephrin expression in podocytes

Increased plasma level of soluble urokinase-type plasminogen activator receptor (suPAR) was associated recently with focal segmental glomerulosclerosis (FSGS). In addition, different clinical studies observed increased concentration of suPAR in various glomerular diseases and in other human pathologies with nephrotic syndromes such as HIV and Hantavirus infection, diabetes and cardiovascular disorders. Here, we show that suPAR induces nephrin down-modulation in human podocytes. This phenomenon is mediated only by full-length suPAR, is time-and dose-dependent and is associated with the suppression of Wilms’ tumor 1 (WT-1) transcription factor expression. Moreover, an antagonist of αvβ3 integrin RGDfv blocked suPAR-induced suppression of nephrin. These in vitro data were confirmed in an in vivo uPAR knock out Plaur^−/− mice model by demonstrating that the infusion of suPAR inhibits expression of nephrin and WT-1 in podocytes and induces proteinuria. This study unveiled that interaction of full-length suPAR with αvβ3 integrin expressed on podocytes results in down-modulation of nephrin that may affect kidney functionality in different human pathologies characterized by increased concentration of suPAR.

TGF-β-activated kinase 1 is crucial in podocyte differentiation and glomerular capillary formation

TGF-β-activated kinase 1 (TAK1) is a key intermediate in signal transduction induced by TGF-β or inflammatory cytokines, such as TNF-α and IL-1, which are potent inducers of podocyte injury responses that lead to proteinuria and glomerulosclerosis. Nevertheless, little is known about the physiologic and pathologic roles of TAK1 in podocytes. To examine the in vivo role of TAK1, we generated podocyte-specific Tak1 knockout mice (Nphs2-Cre(+):Tak1(fx/fx); Tak1(∆/∆)). Targeted deletion of Tak1 in podocytes resulted in perinatal lethality, with approximately 50% of animals dying soon after birth and 90% of animals dying within 1 week of birth. Tak1(∆/∆) mice developed proteinuria from P1 and exhibited delayed glomerulogenesis and reduced expression of Wilms' tumor suppressor 1 and nephrin in podocytes. Compared with Tak1(fx/fx) mice, Tak1(∆/∆) mice exhibited impaired formation of podocyte foot processes that caused disruption of the podocyte architecture with prominent foot process effacement. Intriguingly, Tak1(∆/∆) mice displayed increased expression of vascular endothelial growth factor within the glomerulus and abnormally enlarged glomerular capillaries. Furthermore, 4- and 7-week-old Tak1(∆/∆) mice with proteinuria had increased collagen deposition in the mesangium and the adjacent tubulointerstitial area. Thus, loss of Tak1 in podocytes is associated with the development of proteinuria and glomerulosclerosis. Taken together, our data show that TAK1 regulates the expression of Wilms' tumor suppressor 1, nephrin, and vascular endothelial growth factor and that TAK1 signaling has a crucial role in podocyte differentiation and attainment of normal glomerular microvasculature during kidney development and glomerular filtration barrier homeostasis.

Epigenetic regulation of GATA2 and its impact on normal karyotype acute myeloid leukemia

The GATA2 gene encodes a zinc-finger transcription factor that acts as a master regulator of normal hematopoiesis. Mutations in GATA2 have been implicated in the development of myelodysplastic syndrome and acute myeloid leukemia (AML). Using RNA sequencing we now report that GATA2 is either mutated with a functional consequence, or expressed at low levels in the majority of normal karyotype AML (NK-AML). We also show that low-GATA2-expressing specimens (GATA2(low)) exhibit allele-specific expression (ASE) (skewing) in more than half of AML patients examined. We demonstrate that the hypermethylation of the silenced allele can be reversed by exposure to demethylating agents, which also restores biallelic expression of GATA2. We show that GATA2(low) AML lack the prototypical R882 mutation in DNMT3A frequently observed in NK-AML patients and that The Cancer Genome Atlas AML specimens with DNMT3A R882 mutations are characterized by CpG hypomethylation of GATA2. Finally, we validate that several known missense single-nucleotide polymorphisms in GATA2 are actually loss-of-function variants, which, when combined with ASE, represent the equivalent of homozygous GATA2 mutations. From a broader perspective, this work suggests for the first time that determinants of ASE likely have a key role in human leukemia.

Decreased expression of GATA2 promoted proliferation, migration and invasion of HepG2 in vitro and correlated with poor prognosis of hepatocellular carcinoma

Background

GATA family of transcription factors are critical for organ development and associated with progression of various cancer types. However, their expression patterns and prognostic values for hepatocellular carcinoma (HCC) are still largely unknown.

Methods

Expression of GATA transcription factors in HCC cell lines and tissues (n = 240) were evaluated by RT-qPCR, western blot and immunohistochemistry. Cellular proliferation, migration and invasion of HepG2 was evaluated by CCK-8 kit, scratch wound assay and transwell matrigel invasion assay, respectively.

Results

GATA2 expression was decreased in HCC cell lines (p = 0.056 for mRNA, p = 0.040 for protein) and tissues (p = 1.27E-25) compared with normal hepatocytes. Decreased expression of intratumoral GATA2 protein significantly correlated with elevated alpha feto-protein (p = 2.7E-05), tumor size >5 cm (p = 0.049), absence of tumor capsule (p = 0.002), poor differentiation (p = 0.005), presence of tumor thrombi (p = 0.005) and advanced TNM stage (p = 0.001) and was associated with increased recurrence rate and decreased overall survival rate by univariate (p = 1.6E-04 for TTR, p = 1.7E-04 for OS) and multivariate analyses (HR = 0.63, 95% CI = 0.43–0.90, p = 0.012 for TTR; HR = 0.67, 95% CI = 0.47–0.95, p = 0.026 for OS). RNAi-mediated knockdown of GATA2 expression significantly enhanced proliferation, migration and invasion of HepG2 cell in vitro.

Conclusions

Decreased expression of hematopoietic factor GATA2 was associated with poor prognosis of HCC following resection.

Hypermethylation of the alternative AWT1 promoter in hematological malignancies is a highly specific marker for acute myeloid leukemias despite high expression levels

BACKGROUND

Wilms tumor 1 (WT1) is over-expressed in numerous cancers with respect to normal cells, and has either a tumor suppressor or oncogenic role depending on cellular context. This gene is associated with numerous alternatively spliced transcripts, which initiate from two different unique first exons within the WT1 and the alternative (A)WT1 promoter intervals. Within the hematological system, WT1 expression is restricted to CD34+/CD38- cells and is undetectable after differentiation. Detectable expression of this gene is an excellent marker for minimal residual disease in acute myeloid leukemia (AML), but the underlying epigenetic alterations are unknown.

METHODS

To determine the changes in the underlying epigenetic landscape responsible for this expression, we characterized expression, DNA methylation and histone modification profiles in 28 hematological cancer cell lines and confirmed the methylation signature in 356 cytogenetically well-characterized primary hematological malignancies.

RESULTS

Despite high expression of WT1 and AWT1 transcripts in AML-derived cell lines, we observe robust hypermethylation of the AWT1 promoter and an epigenetic switch from a permissive to repressive chromatin structure between normal cells and AML cell lines. Subsequent methylation analysis in our primary leukemia and lymphoma cohort revealed that the epigenetic signature identified in cell lines is specific to myeloid-lineage malignancies, irrespective of underlying mutational status or translocation. In addition to being a highly specific marker for AML diagnosis (positive predictive value 100%; sensitivity 86.1%; negative predictive value 89.4%), we show that AWT1 hypermethylation also discriminates patients that relapse from those achieving complete remission after hematopoietic stem cell transplantation, with similar efficiency to WT1 expression profiling.

CONCLUSIONS

We describe a methylation signature of the AWT1 promoter CpG island that is a promising marker for classifying myeloid-derived leukemias. In addition AWT1 hypermethylation is ideally suited to monitor the recurrence of disease during remission in patients undergoing allogeneic stem cell transfer.

Bone marrow WT1 levels at diagnosis, post-induction and post-intensification in adult de novo AML

We retrospectively assessed whether normalized bone marrow WT1 levels could be used for risk stratification in a consecutive series of 584 acute myeloid leukemia (AML) patients. A cutoff value of 5065 copies at diagnosis identified two prognostic groups (overall survival (OS): 44 ± 3 vs 36 ± 3%, P=0.023; leukemia-free survival (LFS): 47 ± 3 vs 36 ± 4%, P=0.038; and cumulative incidence of relapse (CIR): 37 ± 3 vs 47 ± 4%, P=:0.043). Three groups were identified on the basis of WT1 levels post-induction: Group 0 (WT1 between 0 and 17.5 copies, 134 patients, OS: 59 ± 4%, LFS:59 ± 4% and CIR: 26 ± 4%); Group 1 (WT1 between 17.6 and 170.5 copies, 160 patients, OS: 48 ± 5%, LFS:41 ± 4% and CIR: 45 ± 4%); and Group 2 (WT1 >170.5 copies, 71 patients, OS: 23 ± 6%, LFS: 19 ± 7% and CIR: 68 ± 8%) (P<0.001). Post-intensification samples distinguished three groups: patients with WT1 >100 copies (47 patients, 16%); an intermediate group of patients with WT1 between 10 and 100 copies (148 patients, 52%); and a third group with WT1 <10 copies (92 patients, 32%). Outcomes differed significantly in terms of OS (30 ± 7%, 59 ± 4%, 72 ± 5%), LFS (24 ± 7%, 46 ± 4%, 65 ± 5%) and relapse probability (CIR 72 ± 7%, 45 ± 4%, 25 ± 5%), all P<0.001. WT1 levels in bone marrow assayed using the standardized ELN method provide relevant prognostic information in de novo AML.

Classification of human genomic regions based on experimentally determined binding sites of more than 100 transcription-related factors

Background

Transcription factors function by binding different classes of regulatory elements. The Encyclopedia of DNA Elements (ENCODE) project has recently produced binding data for more than 100 transcription factors from about 500 ChIP-seq experiments in multiple cell types. While this large amount of data creates a valuable resource, it is nonetheless overwhelmingly complex and simultaneously incomplete since it covers only a small fraction of all human transcription factors.

Results

As part of the consortium effort in providing a concise abstraction of the data for facilitating various types of downstream analyses, we constructed statistical models that capture the genomic features of three paired types of regions by machine-learning methods: firstly, regions with active or inactive binding; secondly, those with extremely high or low degrees of co-binding, termed HOT and LOT regions; and finally, regulatory modules proximal or distal to genes. From the distal regulatory modules, we developed computational pipelines to identify potential enhancers, many of which were validated experimentally. We further associated the predicted enhancers with potential target transcripts and the transcription factors involved. For HOT regions, we found a significant fraction of transcription factor binding without clear sequence motifs and showed that this observation could be related to strong DNA accessibility of these regions.

Conclusions

Overall, the three pairs of regions exhibit intricate differences in chromosomal locations, chromatin features, factors that bind them, and cell-type specificity. Our machine learning approach enables us to identify features potentially general to all transcription factors, including those not included in the data.

miR-15a and miR-16-1 inhibit the proliferation of leukemic cells by down-regulating WT1 protein level

Background

miR-15a and miR-16-1(miR-15a/16-1) have been implicated as tumor suppressors in chronic lymphocytic leukemia, multiple myeloma, and acute myeloid leukemic cells. However the mechanism of inhibiting the proliferation of leukemic cells is poorly understood.

Methods

K562 and HL-60 cells were transfected with pRS-15/16 or pRS-E, cell growth were measured by CCK-8 assay and direct cell count. Meanwhile WT1 protein and mRNA level were measured by Western blotting and quantitative real-time PCR.

Results

In this study we found that over-expression of miR-15a/16-1 significantly inhibited K562 and HL-60 cells proliferation. Enforced expression of miR-15a/16-1 in K562 and HL-60 cells significantly reduced the protein level of WT1 but not affected the mRNA level. However enforced expression of miR-15a/16-1 can not reduce the activity of a luciferase reporter carrying the 3'-untranslated region(3'UTR) of WT1. Silencing of WT1 by specific siRNA suppressed leukemic cells proliferation resembling that of miR-15a/16-1 over-expression. Anti-miR-15a/16-1 oligonucleotides (AMO) reversed the expression of WT1 in K562 and HL-60 cells. Finally, we found a significant inverse correlation between miR-15a or miR-16-1 expression and WT1 protein levels in primary acute myeloid leukemia (AML) blasts and normal controls.

Conclusions

These data suggest that miR-15a/16-1 may function as a tumor suppressor to regulate leukemic cell proliferation potentially by down-regulating the WT1 oncogene. However WT1 is not directly targeted by miR-15a/16-1 through miRNA-mRNA base pairing, therefore more study are required to understand the mechanism by which miR-15a/16-1 downregulate WT1.

Inhibitory mechanism of pure curcumin on Wilms' tumor 1 (WT1) gene expression through the PKCα signaling pathway in leukemic K562 cells

The aim of this study was to investigate the inhibitory mechanism of pure curcumin on WT1 expression in leukemic K562 cells. Pure curcumin suppressed WT1 expression, independent of effects on protein degradation or WT1 mRNA stability. Chromatin immunoprecipitation and reporter gene assays indicate that pure curcumin treatment attenuates WT1 auto-regulation. Interestingly, PKCα inhibition mimicks the repressive effects of pure curcumin in K562 cells. Conversely, myristoylated PKCα over-expression increased WT1 expression and reversed the inhibitory effect of pure curcumin. Our study indicates that pure curcumin attenuates WT1 auto-regulatory function through inhibition of PKCα signaling in K562 cells.

The role of the GATA2 transcription factor in normal and malignant hematopoiesis

Hematopoiesis involves an elaborate regulatory network of transcription factors that coordinates the expression of multiple downstream genes, and maintains homeostasis within the hematopoietic system through the accurate orchestration of cellular proliferation, differentiation and survival. As a result, defects in the expression levels or the activity of these transcription factors are intimately linked to hematopoietic disorders, including leukemia. The GATA family of nuclear regulatory proteins serves as a prototype for the action of lineage-restricted transcription factors. GATA1 and GATA2 are expressed principally in hematopoietic lineages, and have essential roles in the development of multiple hematopoietic cells, including erythrocytes and megakaryocytes. Moreover, GATA2 is crucial for the proliferation and maintenance of hematopoietic stem cells and multipotential progenitors. In this review, we summarize the current knowledge regarding the biological properties and functions of the GATA2 transcription factor in normal and malignant hematopoiesis.

TGF-beta1 reduces Wilms' tumor suppressor gene expression in podocytes

BACKGROUND

Wilms' tumor suppressor gene (WT1) is essential for normal podocyte function, and transforming growth factor (TGF)-beta contributes to focal segmental glomerulosclerosis (FSGS). We aimed to address whether TGF-beta affects WT1 expression in podocytes.

METHODS

A human podocyte cell line treated with TGF-beta1 and kidneys in Alb/TGF-beta1-transgenic mice were analyzed for WT1 expression.

RESULTS

In cultured podocytes, TGF-beta1 reduced WT1 protein expression determined by western blotting beginning at 8 h and decreased WT1 messenger RNA (mRNA) expression measured by quantitative reverse transcription-polymerase chain reaction beginning at 3 h. Knockdown of Smad4 by small hairpin (sh) RNA partially rescued the TGF-beta1-induced reduction of both WT1 protein and mRNA expressions in the cultured podocytes. TGF-beta1 did not alter luciferase activity of the reporter construct for a human WT1 promoter but reduced that for a human WT1 5' enhancer construct, suggesting that TGF-beta1 may regulate WT1 expression by altering the 5' enhancer activity. In the transgenic mice, WT1 protein expression in podocytes was decreased at 1 and 3 weeks of age, while glomeruloclerosis developed after 3 weeks.

CONCLUSION

TGF-beta1 reduces WT1 expression in cultured human podocytes and podocytes in mice before overt glomerulosclerosis begins. The effects are at least partially Smad4 dependent. Our findings identify a novel pathway linking TGF-beta1 to podocyte injury and FSGS. The WT1 reduction may be a useful marker for early podocyte injury.

Down-regulation of PROS1 gene expression by 17beta-estradiol via estrogen receptor alpha (ERalpha)-Sp1 interaction recruiting receptor-interacting protein 140 and the corepressor-HDAC3 complex

Pregnant women show a low level of protein S (PS) in plasma, which is known to be a risk for deep venous thrombosis. 17Beta-estradiol (E(2)), an estrogen that increases in concentration in the late stages of pregnancy, regulates the expression of various genes via the estrogen receptor (ER). Here, we investigated the molecular mechanisms behind the reduction in PS levels caused by E(2) in HepG2-ERalpha cells, which stably express ERalpha, and also the genomic ER signaling pathway, which modulates the ligand-dependent repression of the PSalpha gene (PROS1). We observed that E(2) repressed the production of mRNA and antigen of PS. A luciferase reporter assay revealed that E(2) down-regulated PROS1 promoter activity and that this E(2)-dependent repression disappeared upon the deletion or mutation of two adjacent GC-rich motifs in the promoter. An electrophoretic mobility shift assay and DNA pulldown assay revealed that the GC-rich motifs were associated with Sp1, Sp3, and ERalpha. In a chromatin immunoprecipitation assay, we found ERalpha-Sp protein-promoter interaction involved in the E(2)-dependent repression of PROS1 transcription. Furthermore, we demonstrated that E(2) treatment recruited RIP140 and the NCoR-SMRT-HDAC3 complex to the PROS1 promoter, which hypoacetylated chromatin. Taken together, this suggested that E(2) might repress PROS1 transcription depending upon ERalpha-Sp1 recruiting transcriptional repressors in HepG2-ERalpha cells and, consequently, that high levels of E(2) leading to reduced levels of plasma PS would be a risk for deep venous thrombosis in pregnant women.