The transcription factor deltaEF1 is inversely expressed with type II collagen mRNA and can repress Col2a1 promoter activity in transfected chondrocytes

Potential of Using Infrapatellar–Fat–Pad–Derived Mesenchymal Stem Cells for Therapy in Degenerative Arthritis: Chondrogenesis, Exosomes, and Transcription Regulation

Infrapatellar fat pad–derived mesenchymal stem cells (IPFP-MSCs) are a type of adipose-derived stem cell (ADSC). They potentially contribute to cartilage regeneration and modulation of the immune microenvironment in patients with osteoarthritis (OA). The ability of IPFP-MSCs to increase chondrogenic capacity has been reported to be greater, less age dependent, and less affected by inflammatory changes than that of other MSCs. Transcription-regulatory factors strictly regulate the cartilage differentiation of MSCs. However, few studies have explored the effect of transcriptional factors on IPFP-MSC-based neocartilage formation, cartilage engineering, and tissue functionality during and after chondrogenesis. Instead of intact MSCs, MSC-derived extracellular vesicles could be used for the treatment of OA. Furthermore, exosomes are increasingly being considered the principal therapeutic agent in MSC secretions that is responsible for the regenerative and immunomodulatory functions of MSCs in cartilage repair. The present study provides an overview of advancements in enhancement strategies for IPFP-MSC chondrogenic differentiation, including the effects of transcriptional factors, the modulation of released exosomes, delivery mechanisms for MSCs, and ethical and regulatory points concerning the development of MSC products. This review will contribute to the understanding of the IPFP-MSC chondrogenic differentiation process and enable the improvement of IPFP-MSC-based cartilage tissue engineering.

ZEB1 Mediates Bone Marrow Mesenchymal Stem Cell Osteogenic Differentiation Partly via Wnt/β-Catenin Signaling

Zinc finger E-box-binding homebox 1 (ZEB1) is a zinc-finger transcription factor best known for its role in promoting the epithelial-mesenchymal transition, which is also related to osteogenesis. Here, ZEB1 was investigated for its role in the commitment of bone marrow mesenchymal stem cells (BMSCs) to osteoblasts. In vitro, ZEB1 expression decreased following osteogenic differentiation. Furthermore, silencing of ZEB1 in BMSCs promoted osteogenic activity and mineralization. The increase in osteogenic differentiation induced by si-ZEB1 could be partly rescued by the inhibition of Wnt/β-catenin (si-β-catenin). In vivo, knockdown of ZEB1 in BMSCs inhibited the rapid bone loss of ovariectomized (OVX) mice. ZEB1 expression has also been negatively associated with bone mass and bone formation in postmenopausal women. In conclusion, ZEB1 is an essential transcription factor in BMSC differentiation and may serve as a potential anabolic strategy for treating and preventing postmenopausal osteoporosis (PMOP).

Upregulation Of miR-153 Inhibits Triple-Negative Breast Cancer Progression By Targeting ZEB2-Mediated EMT And Contributes To Better Prognosis

Background

Triple-negative breast cancer (TNBC) is the most malignant type of breast cancer. MicroRNAs (miRs) and their corresponding molecular targets are associated with the occurrence and development of various human malignancies. However, the roles of the microRNA-153 (miR-153) and zinc finger E-box-binding homeobox 2 (ZEB2)-induced epithelial–mesenchymal transition (EMT) in TNBC and predictive effect of miR-153 on the prognosis of TNBC have not been fully elucidated.

Materials and methods

Relative miR-153 expression level was examined by RT-qPCR assay in TNBC tissues of 60 patients and TNBC cell lines (SKBR3, BT-549 and MDA-MB-231). Cell proliferation ability, invasion ability and migration ability were measured by CCK8 assay, Transwell invasion assay and wound healing assay, respectively. Luciferase reporting experiment was used to confirm that there was a miR-153-binding site in ZEB2 3ʹ-UTR. The expression of ZEB2 in tissues and its relationship with miR-153 were analyzed with immunohistochemistry method. Relative ZEB2, E-cadherin, N-cadherin and Vimentin mRNA and protein expression levels were observed with RT-qPCR and Western blot, respectively. Based on risk factors, a prognostic model was established according to the Cox proportional risk model, and the prognostic risk factors of TNBC patients were predicted and analyzed.

Results

The expression of miR-153 in TNBC tissues and cells was declined (all P<0.01), and upregulation of miR-153 inhibited proliferation, invasion and migration of TNBC cells (all P<0.01). In addition, miR-153 regulated ZEB2/EMT link in TNBC, and ZEB2 overexpression reversed the tumor-suppressive effect of miR-153 in TNBC. Moreover, miR-153 was an independent predictive factor that was associated with excellent prognosis in TNBC patients.

Conclusion

miR-153 may inhibit TNBC proliferation, invasion and migration by regulating ZEB2/EMT link. Therefore, miR-153 is expected to be a molecular target and prognostic marker for TNBC.

Agenesis of the corpus callosum, developmental delay, autism spectrum disorder, facial dysmorphism, and posterior polymorphous corneal dystrophy associated with ZEB1 gene deletion

We report on a girl diagnosed prenatally with agenesis of the corpus callosum (ACC) on fetal ultrasound and MRI. On postnatal follow-up she was noted to have developmental delay, facial dysmorphism, autism spectrum disorder, and posterior polymorphous corneal dystrophy (PPD). Array-comparative genomic hybridization analysis (Array-CGH) showed a 2.05 Mb de novo interstitial deletion at 10p11.23p11.22. The deleted region overlaps 1 OMIM Morbid Map gene, ZEB1 (the zinc finger E-box binding homeobox transcription factor 1), previously associated with posterior polymorphous corneal dystrophy type 3 (PPCD3). To our best knowledge this is the first reported case with a deletion of the ZEB1 gene in an individual with ACC and PPD, showing that the haploinsufficiency of the ZEB1 is likely the cause of our patient's phenotype.

Transcriptional regulation of endothelial-to-mesenchymal transition in cardiac fibrosis: role of myocardin-related transcription factor A and activating transcription factor 3

The etiology of cardiac fibrogenesis is quite diverse, but a common feature is the presence of activated fibroblasts. Experimental evidence suggests that a subset of cardiac fibroblasts is derived via transition of vascular endothelial cells into fibroblasts by endothelial-to-mesenchymal transition (EndMT). During EndMT, endothelial cells lose their endothelial characteristics and acquire a mesenchymal phenotype. Molecular mechanisms and the transcriptional mediators controlling EndMT in heart during development or disease remain relatively undefined. Myocardin-related transcription factor A facilitates the transcription of cytoskeletal genes by serum response factor during fibrosis; therefore, its specific role in cardiac EndMT might be of importance. Activation of activating transcription factor 3 (ATF-3) during cardiac EndMT is speculative, since ATF-3 responds to a transforming growth factor β (TGF-β) stimulus and controls the expression of the primary epithelial-to-mesenchymal transition markers Snail, Slug, and Twist. Although the role of TGF-β in EndMT-mediated cardiac fibrosis has been established, targeting of the TGF-β ligand has not proven to be a viable anti-fibrotic strategy owing to the broad functional importance of this ligand. Thus, targeting of downstream transcriptional mediators may be a useful therapeutic approach in attenuating cardiac fibrosis. Here, we discuss some of the transcription factors that may regulate EndMT-mediated cardiac fibrosis and their involvement in type 2 diabetes.

ELF3 modulates type II collagen gene (COL2A1) transcription in chondrocytes by inhibiting SOX9-CBP/p300-driven histone acetyltransferase activity

AIM

We showed previously that E74-like factor 3 (ELF3) protein levels are increased in osteoarthritic (OA) cartilage, that ELF3 accounts for inflammatory cytokine-driven MMP13 gene expression, and that, upon induction by interleukin-1β, ELF3 binds to the COL2A1 promoter and suppresses its activity in chondrocytes. Here, we aimed to further investigate the mechanism/s by which ELF3 represses COL2A1 transcription in chondrocytes.

METHODS AND RESULTS

We report that ELF3 inhibits Sox9-driven COL2A1 promoter activity by interfering with the activator functions of CBP/300 and Sox9. Co-transfection of the pGL2B-COL2A1 (-577/+3428 bp) reporter construct with Sox9 and with Sox5 and/or Sox6 increased COL2A1 promoter activity, and ELF3 overexpression significantly reduced the promoter transactivation. Co-transfection of ELF3 with the pLuc 4x48 enhancer construct, containing the 89-bp COL2A1 promoter and lacking the previously defined ELF3 binding sites, decreased both basal and Sox9-driven promoter activity. Co-transfection of ELF3 with a Gal4 reporter construct also inhibited Gal4-Sox9-driven transactivation, suggesting that ELF3 directly interacts with Sox9. Using truncated Sox9 fragments, we found that ELF3 interacts directly with the HMG domain of Sox9. Importantly, overexpression of ELF3 significantly decreased Sox9/CBP-dependent HAT activity. Finally, we show evidence that increased ELF3 mRNA expression in OA chondrocytes correlates with hypermethylation of the proximal promoter, suggesting that ELF3 transcription is subjected to epigenetic control in OA disease.

CONCLUSION

Our results highlight the contribution of ELF3 to transcriptional regulation of COL2A1 and its potential role in OA disease, and uncover epigenetic mechanisms at play in the regulation of ELF3 and its downstream targets in articular chondrocytes.

Extracellular vesicles in the pathogenesis of rheumatoid arthritis and osteoarthritis

Osteoarthritis (OA) and rheumatoid arthritis (RA) are both debilitating diseases that cause significant morbidity in the US population. Extracellular vesicles (EVs), including exosomes and microvesicles, are now recognized to play important roles in cell-to-cell communication by transporting various proteins, microRNAs (miRNAs), and mRNAs. EV-derived proteins and miRNAs impact cell viability and cell differentiation, and are likely to play a prominent role in the pathophysiology of both OA and RA. Some of the processes by which these membrane-bound vesicles can alter joint tissue include extracellular matrix degradation, cell-to-cell communication, modulation of inflammation, angiogenesis, and antigen presentation. For example, EVs from IL-1β-stimulated fibroblast-like synoviocytes have been shown to induce osteoarthritic changes in chondrocytes. RA models have shown that EVs stimulated with inflammatory cytokines are capable of inducing apoptosis resistance in T cells, presenting antigen to T cells, and causing extracellular damage with matrix-degrading enzymes. EVs derived from rheumatoid models have also been shown to induce secretion of COX-2 and stimulate angiogenesis. Additionally, there is evidence that synovium-derived EVs may be promising biomarkers of disease in both OA and RA. The characterization of EVs in the joint space has also opened up the possibility for delivery of small molecules. This article reviews current knowledge on the role of EVs in both RA and OA, and their potential role as therapeutic targets for modulation of these debilitating diseases.

Investigating the Molecular Basis of PPCD3: Characterization of ZEB1 Regulation of COL4A3 Expression

PURPOSE

To investigate the role of the zinc finger e-box binding homeobox 1 (ZEB1) transcription factor in posterior polymorphous corneal dystrophy 3 by demonstrating its ability to regulate type IV collagen gene transcription via binding to putative E2 box motifs.

METHODS

Putative E2 box motifs were identified by in silico analysis within the promoter region of collagen, type IV, alpha3 (COL4A3) and collagen, type IV, alpha4 (COL4A4). To test the ability of ZEB1 to bind to each identified E2 box, electrophoretic mobility shift assays were performed by incubating ZEB1-enriched nuclear extracts with DIG-labeled probes containing one of each of the identified E2 box motifs. Dual-luciferase reporter assays were performed to test the effects of ZEB1 on the luciferase activity of COL4A3 and cadherin 1 (CDH1) promoter constructs, and to determine the effect of a ZEB1 truncating mutation on CDH1 promoter activity.

RESULTS

ZEB1 exhibited binding to six of the nine COL4A3 E2 box probes, whereas no binding was observed for either of the two COL4A4 E2 box probes. ZEB1 overexpression resulted in reduced activity of the COL4A3 promoter construct containing all identified E2 box motifs, whereas a truncating ZEB1 mutation led to the loss of ZEB1-dependent repression of the CDH1 promoter.

CONCLUSIONS

COL4A3 gene expression is negatively regulated by ZEB1 binding to E2 box motifs in the COL4A3 promoter region. Therefore, the altered expression of type IV collagens, particularly COL4A3, in the corneal endothelium in individuals with PPCD3 is likely due to reduced transcriptional repression in the setting of a single functional ZEB1 allele.

Transcription factors related to chondrogenesis in pleomorphic adenoma of the salivary gland: a mechanism of mesenchymal tissue formation

In salivary gland pleomorphic adenoma, expression of extracellular matrix (ECM) substances indicates that tumor epithelial cells are becoming chondrogenic and will produce cartilage-like mesenchymal tissues. Sox9, the master transcription factor of chondrogenesis, is expressed in mouse salivary gland cells. To clarify the mechanism behind chondrogenesis in tumor epithelial cells, we examined the expression of transcription factors related to chondrogenesis in tumors and salivary glands. Reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative real-time RT-PCR, and immunostaining were performed on pleomorphic adenoma tissues, salivary gland tissues, and human submandibular gland (HSG) cells. The mRNAs of essential transcription factors for chondrogenesis-Sox9, Sox6, and Sox5-were detected in both tumor and salivary gland tissues. The mRNAs of aggrecan and type II collagen-cartilage-specific ECM substances-were detected only in tumors. Sox9 and Sox6 proteins were colocalized in many epithelial cells in tumors and salivary glands. Tumor epithelial cells also possessed aggrecan protein and occasionally type II collagen protein. Moreover, mRNAs for transcription repressors of chondrogenesis δEF1 and AP-2α were detected in both tumors and salivary glands, whereas Twist1 mRNA was detected only in salivary glands and was at significantly low-to-undetectable levels in tumors. Twist1 protein was localized in the Sox9-expressing salivary gland cells. HSG cells expressed Sox9, Sox6, and Twist1, but not aggrecan or type II collagen, and thus were similar to salivary gland cells. Twist1 depletion by Twist1 siRNA led to the upregulation of aggrecan and type II collagen mRNA expression in HSG cells. In contrast, forced expression of Twist1, using Twist1 cDNA, resulted in the downregulation of both these genes. Taken together, these results indicate that salivary gland cells have a potential for chondrogenesis, and Twist1 depletion concomitant with neoplastic transformation, which would permit tumor epithelial cells to produce cartilage-like mesenchymal tissues in salivary gland pleomorphic adenoma.

Effects of miR-200c on the migration and invasion abilities of human prostate cancer Du145 cells and the corresponding mechanism

microRNAs (miRNAs) have played a key role in human tumorigenesis, tumor progression, and metastasis. On the one hand, miRNAs are aberrantly expressed in many types of human cancer; on the other hand, miRNAs can function as tumor suppressors or oncogenes that target many cancer-related genes. This study aimed to investigate the effects of miRNA-200c (miR-200c) on the biological behavior and mechanism of proliferation, migration, and invasion in the prostate cancer cell line Du145. In this study, Du145 cells were transfected with miR-200c mimics or negative control miR-NC by using an X-tremeGENE siRNA transfection reagent. The relative expression of miR-200c was measured by RT-PCR. The proliferation, migration, and invasion abilities of Du145 cells were detected by CCK8 assays, migration assays and invasion assays, respectively. The expressions of ZEB1, E-cadherin, and vimentin were observed by western blot. Results showed that DU145 cells exhibited a high expression of miR-200c compared with immortalized normal prostate epithelial cell RWPE-1. Du145 cells were then transfected with miR-200c mimics and displayed lower abilities of proliferation, migration, and invasion than those transfected with the negative control. The protein levels of ZEB1 and vimentin were expressed at a low extent in Du145 cells, which were transfected with miR-200c mimics; by contrast, E-cadherin was highly expressed. Hence, miR-200c could significantly inhibit the proliferation of the prostate cancer cell line Du145; likewise, miR-200c could inhibit migration and invasion by epithelial-mesenchymal transition.

Functional impact of ZEB1 mutations associated with posterior polymorphous and Fuchs' endothelial corneal dystrophies

PURPOSE

To assess the impact of zinc finger E-box binding homeobox 1 (ZEB1) gene mutations associated with posterior polymorphous corneal dystrophy 3 (PPCD3) and Fuchs' endothelial corneal dystrophy (FECD).

METHODS

Thirteen of the 27 previously reported ZEB1 truncating mutations associated with PPCD3 and the six previously reported ZEB1 missense mutations associated with FECD were generated and transiently transfected into a corneal endothelial cell line. Protein abundance was determined by immunoblotting, while intracellular localization was determined by fluorescence confocal microscopy.

RESULTS

Three of the 13 ZEB1 truncated mutants, and none of the missense mutants, showed significant decrease in mutant ZEB1 protein levels. Predominant nuclear localization was observed for truncated ZEB1 mutant proteins with a predicted molecular weight of less than 92 kilodaltons. The two largest mutant proteins that lacked a putative nuclear localization signal (NLS), p.(Ser638Cysfs*5) and p.(Gln884Argfs*37), primarily localized to the cytoplasm, while the NLS-containing mutant proteins, p.(Glu997Alafs*7) and p.(Glu1039Glyfs*6), primarily localized to the nucleus. All the missense ZEB1 mutant proteins were exclusively present in the nucleus.

CONCLUSIONS

ZEB1 truncating mutations result in a significant decrease and/or impaired nuclear localization of the encoded protein, indicating that ZEB1 haploinsufficiency in PPCD3 may result from decreased protein production and/or impaired cellular localization. Conversely, as the reported ZEB1 missense mutations do not significantly impact protein abundance or nuclear localization, the effect of these mutations on ZEB1 function and their relationship to FECD, if any, remain to be elucidated.

δEF1 upregulates CDK4 transcription via the E2-box element on the CDK4 promoter

The zinc finger-homeodomain transcription factor, δ-crystallin enhancer factor 1 (δEF1) has been identified as a regulatory factor involved in the promotion of breast cancer cell proliferation via the downregulation of p21 and the upregulation of cyclin-dependent kinase-2 (CDK2) and CDK4 expression. However, the molecular mechanisms underlying the regulation of CDK4 expression by δEF1 have not yet been elucidated. The present study demonstrated that the ectopic expression of δEF1 in MDA-MB-231 breast cancer cells significantly increased the activity of the CDK4 promoter. Deletion of the E2-box (CACGTG), which is located at position -197/-191 on the human CDK4 promoter, significantly attenuated the activation of CDK4 transcription by δEF1. In addition, a CDK4 promoter-M construct was generated via site-directed mutagenesis of the E2-box on the human CDK4 promoter. Luciferase assay showed that the activation of CDK4 promoter-M activity by δEF1 was markedly decreased compared with the CDK4-promoter-0.4k promoter. Knockdown of δEF1 using RNA interference resulted in the inhibition of CDK4 promoter activity. These observations suggest that δEF1 upregulates CDK4 transcription via the E2-box element on the CDK4 promoter.

Involvement of renal corpuscle microRNA expression on epithelial-to-mesenchymal transition in maternal low protein diet in adult programmed rats

Prior study shows that maternal protein-restricted (LP) 16-wk-old offspring have pronounced reduction of nephron number and arterial hypertension associated with unchanged glomerular filtration rate, besides enhanced glomerular area, which may be related to glomerular hyperfiltration/overflow and which accounts for the glomerular filtration barrier breakdown and early glomerulosclerosis. In the current study, LP rats showed heavy proteinuria associated with podocyte simplification and foot process effacement. TGF-β1 glomerular expression was significantly enhanced in LP. Isolated LP glomeruli show a reduced level of miR-200a, miR-141, miR-429 and ZEB2 mRNA and upregulated collagen 1α1/2 mRNA expression. By western blot analyzes of whole kidney tissue, we found significant reduction of both podocin and nephrin and enhanced expression of mesenchymal protein markers such as desmin, collagen type I and fibronectin. From our present knowledge, these are the first data showing renal miRNA modulation in the protein restriction model of fetal programming. The fetal-programmed adult offspring showed pronounced structural glomerular disorders with an accentuated and advanced stage of fibrosis, which led us to state that the glomerular miR-200 family would be downregulated by TGF-β1 action inducing ZEB 2 expression that may subsequently cause glomeruli epithelial-to-mesenchymal transition.

MicroRNA circuits in transforming growth factor-β actions and diabetic nephropathy

Diabetes is associated with significantly increased rates of kidney disease or diabetic nephropathy (DN), a severe microvascular complication that can lead to end-stage renal disease. End-stage renal disease needs to be treated by dialysis or kidney transplantation and also is associated with cardiovascular disease and macrovascular complications. Therefore, effective renal protection is critical to reduce the rates of mortality associated with diabetes. Although key signal transduction and gene regulation mechanisms have been identified and several drugs are currently in clinical use, the rates of DN are still escalating, suggesting the imperative need to identify new biomarkers and drug targets. The recent discovery of microRNAs (miRNAs) and their cellular functions provide an opportunity to fill these critical gaps. Because miRNAs can modulate the actions of key factors involved in DN such as transforming growth factor-β, they could be novel targets for the treatment of DN. This review covers the recent studies on the roles of miRNAs and miRNA circuits in transforming growth factor-β actions and in DN.

Overexpression of ZEB1 associated with metastasis and invasion in patients with gastric carcinoma

The aim of this study was to investigate the expression of ZEB1 in gastric carcinoma, its correlation with the clinicopathology of gastric carcinoma, and the role of ZEB1 in invasion and metastasis in gastric carcinoma. ZEB1 expression was analyzed by immunohistochemistry and Western blot in 45 gastric carcinoma tissue samples that contained the adjacent gastric mucosa. The correlation between ZEB1 expression, the occurrence and development of gastric cancer, and clinical pathology was investigated. ZEB1 expression in the human gastric carcinoma cell line AGS was downregulated by RNA interference, and changes in ZEB1 expression corresponded with changes in the invasive and metastatic ability of AGS cells. Immunohistochemistry revealed that ZEB1 protein expression in gastric carcinoma tissues was significantly higher than in normal gastric mucosa tissues (p < 0.001). A lower degree of differentiation of gastric cancer (p = 0.009), a higher TNM (tumor, node, and metastasis) stage (p = 0.010), and a larger scope of invasion were correlated with higher expression of ZEB1 (p = 0.041, 0.002). However, the expression of ZEB1 in gastric carcinoma tissue was independent of gender, age, and tumor size (p > 0.05). Western blot results also showed that ZEB1 protein expression was significantly higher in gastric carcinoma tissue than in the adjacent normal gastric mucosa tissue (p = 0.008). A lower degree of differentiation of the gastric carcinoma correlated with a higher TNM stage, and a larger scope of invasion correlated with increased ZEB1 expression (p = 0.023). Transfection of ZEB1 siRNA in AGS cells significantly decreased the expression level of ZEB1 protein (p = 0.035). Furthermore, the number of cells that could pass through the Transwell chamber was significantly lower in the transfected group than in the non-transfected control group (p = 0.039), indicating that the suppression of ZEB1 expression could significantly reduce the invasive and metastatic ability of AGS cells (p = 0.005). Concluding, in gastric carcinoma tissue, overexpression of ZEB1 may be related to the occurrence and development as well as invasion and metastasis of gastric carcinoma.

Meta-profiles of gene expression during aging: limited similarities between mouse and human and an unexpectedly decreased inflammatory signature

BACKGROUND

Skin aging is associated with intrinsic processes that compromise the structure of the extracellular matrix while promoting loss of functional and regenerative capacity. These processes are accompanied by a large-scale shift in gene expression, but underlying mechanisms are not understood and conservation of these mechanisms between humans and mice is uncertain.

RESULTS

We used genome-wide expression profiling to investigate the aging skin transcriptome. In humans, age-related shifts in gene expression were sex-specific. In females, aging increased expression of transcripts associated with T-cells, B-cells and dendritic cells, and decreased expression of genes in regions with elevated Zeb1, AP-2 and YY1 motif density. In males, however, these effects were contrasting or absent. When age-associated gene expression patterns in human skin were compared to those in tail skin from CB6F1 mice, overall human-mouse correspondence was weak. Moreover, inflammatory gene expression patterns were not induced with aging of mouse tail skin, and well-known aging biomarkers were in fact decreased (e.g., Clec7a, Lyz1 and Lyz2). These unexpected patterns and weak human-mouse correspondence may be due to decreased abundance of antigen presenting cells in mouse tail skin with age.

CONCLUSIONS

Aging is generally associated with a pro-inflammatory state, but we have identified an exception to this pattern with aging of CB6F1 mouse tail skin. Aging therefore does not uniformly heighten inflammatory status across all mouse tissues. Furthermore, we identified both intercellular and intracellular mechanisms of transcriptome aging, including those that are sex- and species-specific.

Clinicopathological significance of ZEB1 protein in patients with hepatocellular carcinoma

BACKGROUND

ZEB1, a member of the ZFH family of proteins (zinc-finger E-box binding homeobox), plays a central role in epithelial-mesenchymal transition (EMT) during carcinogenesis. In this study, we investigated the expression of ZEB1 in patients with hepatocellular carcinoma (HCC) and its clinical effects with underlying mechanisms.

METHODS

Expression levels of ZEB1 were assessed by Western blot in 5 HCC cell lines and in paired cancerous and noncancerous tissues from 110 patients with HCC. Short-hairpin RNA (shRNA) interference for ZEB1 was performed in MHCC-97H cell line.

RESULTS

ZEB1 protein was detected at a relatively high level in metastatic human HCC cell lines (MHCC-97L and MHCC-97H) when compared with that in nonmetastatic HCC cell lines (Hep3B, PLC and Huh-7). ZEB1 was expressed at high levels in 72 of 110 HCC patients (65.4%) and correlated with advanced TNM stage, tumor size >5 cm, intrahepatic metastasis, vascular invasion, and frequent early recurrence. The results of multivariate analysis revealed that ZEB1 high expression was a significant prognostic factor for poor overall and disease-free survivals. Silencing ZEB1 resulted in significant suppression of motility of MHCC-97H cell line, which was accompanied with increased expression of the epithelial marker E-cadherin and decreased expression of the mesenchymal markers N-cadherin and vimentin. Furthermore, silencing ZEB1 prevented the spread of intrahepatic metastasis and increased overall survival in mouse orthotopic tumor models.

CONCLUSIONS

This study shows that ZEB1 high expression was correlated with HCC malignant progression and subsequent poor patient survival by induction of EMT changes.

ZEB1 is estrogen responsive in vitro in human foreskin cells and is over expressed in penile skin in patients with severe hypospadias

PURPOSE

We determined the effect of estrogen on ZEB1 in vitro and tested the hypothesis that ZEB1 is over expressed in the penile skin of subjects with hypospadias.

MATERIALS AND METHODS

Hs68 cells, a fibroblast cell line derived from human foreskin, were exposed to 0, 1, 10 and 100 nM estrogen, and the expression level of ZEB1 was assessed using reverse transcription real-time polymerase chain reaction, Western blot and immunocytochemical analysis. Next, preputial skin was prospectively collected from case and control subjects at hypospadias repair (37 cases) and circumcision (11). Hypospadias was classified as severe (13 cases) or mild (24) based on the position of the urethral meatus. ZEB1 expression was quantified using reverse transcription real-time polymerase chain reaction, Western blot and immunohistochemical analysis.

RESULTS

Estrogen increased ZEB1 expression at the mRNA and protein levels in Hs68 cells in a concentration dependent fashion (p <0.01). Subjects with severe hypospadias had significantly higher ZEB1 mRNA levels and protein expression compared to controls or subjects with mild hypospadias (both p <0.01). Subjects with severe hypospadias had increased expression of ZEB1 in the basal layers of the preputial epidermis.

CONCLUSIONS

Estrogen increases ZEB1 expression in a human foreskin fibroblast cell line in vitro. Furthermore, ZEB1 is significantly over expressed in the penile skin of subjects with severe hypospadias. We propose that ZEB1 overexpression may contribute to development of hypospadias and may mediate the effect of estrogen on developing external male genitalia.

A microRNA circuit mediates transforming growth factor-β1 autoregulation in renal glomerular mesangial cells

Enhanced transforming growth factor-β1 (TGF-β1) expression in renal cells promotes fibrosis and hypertrophy during the progression of diabetic nephropathy. The TGF-β1 promoter is positively controlled by the E-box regulators, upstream stimulatory factors (USFs), in response to diabetic (high glucose) conditions; however, it is not clear whether TGF-β1 is autoregulated by itself. As changes in microRNAs (miRNAs) have been implicated in kidney disease, we tested their involvement in this process. TGF-β1 levels were found to be upregulated by microRNA-192 (miR-192) or miR-200b/c in mouse mesangial cells. Amounts of miR-200b/c were increased in glomeruli from type 1 (streptozotocin) and type 2 (db/db) diabetic mice, and in mouse mesangial cells treated with TGF-β1 in vitro. Levels of miR-200b/c were also upregulated by miR-192 in the mesangial cells, suggesting that miR-200b/c are downstream of miR-192. Activity of the TGF-β1 promoter was upregulated by TGF-β1 or miR-192, demonstrating that the miR-192-miR-200 cascade induces TGF-β1 expression. TGF-β1 increased the occupancy of activators USF1 and Tfe3, and decreased that of the repressor Zeb1 on the TGF-β1 promoter E-box binding sites. Inhibitors of miR-192 decreased the expression of miR-200b/c, Col1a2, Col4a1, and TGF-β1 in mouse mesangial cells, and in mouse kidney cortex. Thus, miRNA-regulated circuits may amplify TGF-β1 signaling, accelerating chronic fibrotic diseases such as diabetic nephropathy.

Smad interacting protein 1 as a regulator of skin fibrosis in pathological scars

Keloids and hypertrophic scars are significant symptomatic clinical problems characterized by the excessive and abnormal deposition of collagen-based extracellular matrix (ECM) components. However, the molecular basis of keloid and hypertrophic scar formation has not been fully elucidated. Here, we demonstrated that down-regulation of the transcription factor Smad interacting protein 1 (SIP1) could be relevant to keloid and hypertrophic scar formation. The results of the present study show that the level of SIP1 mRNA is significantly decreased in pathological scar tissues and in normal skin and pathological scar fibroblasts treated with transforming growth factor β1 (TGF-β1). In contrast, the expression of SIP1 mRNA is not decreased in normotrophic scar samples. The SIP1 mRNA level inversely correlates with the mRNA level of type I collagen (COL1A2) and directly correlates with the mRNA level of matrix metalloproteinase-1 (MMP1). Overexpression of SIP1 in keloid and hypertrophic scar fibroblasts represses TGF-β1-stimulated COL1A2 expression and induces MMP1 expression. Alternatively, knockdown of SIP1 in normal skin fibroblasts enhance TGF-β1-induced COL1A2 levels. These findings suggest that SIP1 could be a regulator of skin fibrosis, and depletion of SIP1 in pathological scar tissues could result in an up-regulation of collagen and down-regulation of matrix metalloproteinase, leading to an abnormal accumulation of ECM along with fibrosis and pathological scar formation.

Identification of DeltaEF1 as a novel target that is negatively regulated by LMO2 in T-cell leukemia

The lmo2 gene is a specific oncogene in T-cell leukemia, for its ectopic expression causes both increased pro-T-cell proliferation and differentiation arrest, leading to the onset of leukemia. Notably, DeltaEF1 (also known as ZEB1), a member of zinc finger-homeodomain family transcription factor, also exhibits crucial function in promoting T-cell differentiation. In this study, we found that DeltaEF1 was positively regulated by T-lineage-specific transcriptional regulator GATA3, while ectopically expressed LMO2 targeted to DeltaEF1 promoter by interaction with GATA3 and inhibited DeltaEF1 expression in transcriptional level. Moreover, LMO2 interacted with the N-terminal zinc finger domain of DeltaEF1 protein and inhibited its positive transcriptional regulatory function by this interaction. Taken together, our findings revealed that ectopically expressed LMO2 impaired the function of DeltaEF1 in both transcriptional and protein levels and identified DeltaEF1 as a novel pathogenic target of LMO2 in T-cell leukemia.

ZEB1 in Pancreatic Cancer

Pancreatic cancer is one of the most malignant human neoplasias. On the molecular level, epithelial-mesenchymal transition (EMT) has been demonstrated to contribute to the malignant phenotype of pancreatic cancer cells. ZEB1 is a transcriptional repressor that has been identified as an inducer of EMT. A negative feedback loop between ZEB1 and microRNA-200c has been shown to regulate this EMT induction in various models. With respect to pancreatic cancer, primary effects of EMT comprise increased local and distant tumor cell dissemination. Another recently described feature of the EMT is the acquisition of cancer stem cell traits. For pancreatic cancer cells, antagonism between ZEB1 and stemness-inhibiting micro-RNAs has been demonstrated to contribute to this process, providing experimental support for the migrating cancer stem cell (MCSC) hypothesis. ZEB1 has also been shown to be associated with drug resistance of pancreatic cancer cells. This article reviews the biological functions of ZEB1 with a focus on pancreatic cancer.

Post-transcriptional up-regulation of Tsc-22 by Ybx1, a target of miR-216a, mediates TGF-{beta}-induced collagen expression in kidney cells

Increased accumulation of extracellular matrix proteins and hypertrophy induced by transforming growth factor-β1 (TGF-β) in renal mesangial cells (MC) are hallmark features of diabetic nephropathy. Although the post-transcriptional regulation of key genes has been implicated in these events, details are not fully understood. Here we show that TGF-β increased microRNA-216a (miR-216a) levels in mouse MC, with parallel down-regulation of Ybx1, a miR-216a target and RNA-binding protein. TGF-β also enhanced protein levels of Tsc-22 (TGF-β-stimulated clone 22) and collagen type I α-2 (Col1a2) expression in MC through far upstream enhancer E-boxes by interaction of Tsc-22 with an E-box regulator, Tfe3. Ybx1 colocalized with processing bodies in MC and formed a ribonucleoprotein complex with Tsc-22 mRNA, and this complex formation was reduced by TGF-β, miR-216a mimics, or Ybx1 shRNA to increase Tsc-22 protein levels but enhanced by miR-216a inhibitor oligonucleotides. Chromatin immunoprecipitation (ChIP) assays revealed that TGF-β could increase the occupancies of Tsc-22 and Tfe3 on enhancer E-boxes of Col1a2. Co-immunoprecipitation assays revealed that TGF-β promoted the interaction of Tsc-22 with Tfe3. These results demonstrate that post-transcriptional regulation of Tsc-22 mediated through Ybx1, a miR-216a target, plays a key role in TGF-β-induced Col1a2 in MC related to the pathogenesis of diabetic nephropathy.

The ZEB1 transcription factor is a novel repressor of adiposity in female mice

Background

Four genome-wide association studies mapped an “obesity” gene to human chromosome 10p11–12. As the zinc finger E-box binding homeobox 1 (ZEB1) transcription factor is encoded by the TCF8 gene located in that region, and as it influences the differentiation of various mesodermal lineages, we hypothesized that ZEB1 might also modulate adiposity. The goal of these studies was to test that hypothesis in mice.

Methodology/Principal Findings

To ascertain whether fat accumulation affects ZEB1 expression, female C57BL/6 mice were fed a regular chow diet (RCD) ad libitum or a 25% calorie-restricted diet from 2.5 to 18.3 months of age. ZEB1 mRNA levels in parametrial fat were six to ten times higher in the obese mice. To determine directly whether ZEB1 affects adiposity, wild type (WT) mice and mice heterozygous for TCF8 (TCF8+/−) were fed an RCD or a high-fat diet (HFD) (60% calories from fat). By two months of age on an HFD and three months on an RCD, TCF8+/− mice were heavier than WT controls, which was attributed by Echo MRI to increased fat mass (at three months on an HFD: 0.517±0.081 total fat/lean mass versus 0.313±0.036; at three months on an RCD: 0.175±0.013 versus 0.124±0.012). No differences were observed in food uptake or physical activity, suggesting that the genotypes differ in some aspect of their metabolic activity. ZEB1 expression also increases during adipogenesis in cell culture.

Conclusion/Significance

These results show for the first time that the ZEB1 transcription factor regulates the accumulation of adipose tissue. Furthermore, they corroborate the genome-wide association studies that mapped an “obesity” gene at chromosome 10p11–12.

DeltaEF1 promotes breast cancer cell proliferation through down-regulating p21 expression

Although the zinc finger-homeodomain transcription factor deltaEF1 is implied as a regulatory factor at the crossroad between proliferation and differentiation in carcinogenesis, its potential effect in the regulation of cell cycle progression has not been well elucidated. In our present study, we provide novel finding that, in breast cancer, the ectopic expression of deltaEF1 in MDA-MB-231 cells significantly promoted cell proliferation by increasing the cell number in S phase of the cell cycle. In contrast, deltaEF1 knockdown by RNA interference exhibited an opposite effect, highlighting a potent role of deltaEF1 to promote G1-S transition of breast cancer cells. Moreover, we demonstrated that deltaEF1 down-regulated p21 and concurrently up-regulated the expressions of CDK2 and CDK4 during this process. Further, deltaEF1 inhibited p21 transcription by recruiting to the E(2) box element on the p21 promoter. Depletion of endogenous deltaEF1 in MDA-MB-231 cells was sufficient to allow an inherent release of p21 expression, thus resulting in the cell cycle arrest. In addition, the stimulatory effect of deltaEF1 on cell proliferation through p21 regulation was supported by an inverse correlation of deltaEF1 and p21 expressions observed in both breast cancer cell lines and clinical tumor specimens. Taken together, these observations suggest a dual effect of deltaEF1 in promoting breast cancer cell proliferation, by differentially regulating the cell cycle regulatory proteins.

delta-EF1 is a negative regulator of Ihh in the developing growth plate

Indian hedgehog (Ihh) regulates proliferation and differentiation of chondrocytes in the growth plate. Although the biology of Ihh is currently well documented, its transcriptional regulation is poorly understood. delta-EF1 is a two-handed zinc finger/homeodomain transcriptional repressor. Targeted inactivation of mouse delta-EF1 leads to skeletal abnormalities including disorganized growth plates, shortening of long bones, and joint fusions, which are reminiscent of defects associated with deregulation of Ihh signaling. Here, we show that the absence of delta-EF1 results in delayed hypertrophic differentiation of chondrocytes and increased cell proliferation in the growth plate. Further, we demonstrate that delta-EF1 binds to the putative regulatory elements in intron 1 of Ihh in vitro and in vivo, resulting in down-regulation of Ihh expression. Finally, we show that delta-EF1 haploinsufficiency leads to a postnatal increase in trabecular bone mass associated with enhanced Ihh expression. In summary, we have identified delta-EF1 as an in vivo negative regulator of Ihh expression in the growth plate.

MicroRNAs and their role in progressive kidney diseases

MicroRNAs (miRs) are a family of short non-coding RNAs. These endogenously produced factors have been shown to play important roles in gene regulation. The discovery of miRs has greatly expanded our knowledge of gene regulation at the posttranscriptional level. miRs inhibit target gene expression by blocking protein translation or by inducing mRNA degradation and therefore have the potential to modulate physiologic and pathologic processes. The imperative need to determine their cellular targets and disease relevance has sparked an unprecedented explosion of research in the miR field. Recent findings have revealed critical functions for specific miRs in cellular events such as proliferation, differentiation, development, and immune responses and in the regulation of genes relevant to human diseases. Of particular interest to renal researchers are recent reports that key miRs are highly expressed in the kidney and can act as effectors of TGF-beta actions and high glucose in diabetic kidney disease. Moreover, podocyte-specific deletion of Dicer, a key enzyme involved in miR biogenesis, led to proteinuria and severe renal dysfunction in mice. Hence, studies aimed at determining the in vitro and in vivo functions of miRs in the kidney could determine their value as therapeutic targets for progressive renal glomerular and tubular diseases. Translational approaches could be facilitated by the development of effective inhibitors of specific miRs and methods for optimal delivery of anti-miRs to the kidney. The major goal of this review is to highlight key functions of these miRs and their relationships to human diseases, with special emphasis on diabetic kidney disease.

E-cadherin, beta-catenin, and ZEB1 in malignant progression of cancer

The embryonic program 'epithelial-mesenchymal transition' (EMT) is activated during tumor invasion in disseminating cancer cells. Characteristic to these cells is a loss of E-cadherin expression, which can be mediated by EMT-inducing transcriptional repressors, e.g. ZEB1. Consequences of a loss of E-cadherin are an impairment of cell-cell adhesion, which allows detachment of cells, and nuclear localization of beta-catenin. In addition to an accumulation of cancer stem cells, nuclear beta-catenin induces a gene expression pattern favoring tumor invasion, and mounting evidence indicates multiple reciprocal interactions of E-cadherin and beta-catenin with EMT-inducing transcriptional repressors to stabilize an invasive mesenchymal phenotype of epithelial tumor cells.

ZEB1 expression in type I vs type II endometrial cancers: a marker of aggressive disease

Zinc-finger E-box-binding homeobox 1 (ZEB1) is a transcription factor containing two clusters of Kruppel-type zinc-fingers, by which it binds E-box-like sequences on target DNAs. A role for ZEB1 in tumor progression, specifically, epithelial to mesenchymal transitions, has recently been revealed. ZEB1 acts as a master repressor of E-cadherin and other epithelial markers. We previously demonstrated that ZEB1 is confined to the stromal compartment in normal endometrium and low-grade endometrial cancers. Here, we quantify ZEB1 protein expression in endometrial samples from 88 patients and confirm that it is expressed at significantly higher levels in the tumor-associated stroma of low-grade endometrioid adenocarcinomas (type I endometrial cancers) compared to hyperplastic or normal endometrium. In addition, as we previously reported, ZEB1 is aberrantly expressed in the epithelial-derived tumor cells of highly aggressive endometrial cancers, such as FIGO grade 3 endometrioid adenocarcinomas, uterine serous carcinomas, and malignant mixed Müllerian tumors (classified as type II endometrial cancers). We now demonstrate, in both human endometrial cancer specimens and cell lines, that when ZEB1 is inappropriately expressed in epithelial-derived tumor cells, E-cadherin expression is repressed, and that this inverse relationship correlates with increased migratory and invasive potential. Forced expression of ZEB1 in the nonmigratory, low-grade, relatively differentiated Ishikawa cell line renders them migratory. Conversely, reduction of ZEB1 in a highly migratory and aggressive type II cell line, Hec50co, results in reduced migratory capacity. Thus, ZEB1 may be a biomarker of aggressive endometrial cancers at high risk of recurrence. It may help identify women who would most benefit from chemotherapy. Furthermore, if expression of ZEB1 in type II endometrial cancers could be reversed, it might be exploited as therapy for these highly aggressive tumors.

Transcriptional regulation of bone marrow thrombopoietin by platelet proteins

Platelet production is regulated primarily by the cytokine thrombopoietin (TPO). Although TPO is expressed in several different tissues, only in the bone marrow has the level of expression been reported to increase in response to reduced numbers of platelets. In these studies, we demonstrate that platelet granule proteins are able to transcriptionally repress TPO mRNA expression in a marrow stromal cell line as well as in primary bone marrow stromal cell cultures. Like TPO mRNA, secretion of TPO protein was also suppressed by serum treatment. Reporter gene constructs indicate that DNA elements located in an approximately 1.9-kb region between 250-bp upstream of the transcriptional initiation site and the middle of the second intron are able to mediate the transcriptional repression.

Posterior polymorphous corneal dystrophy is associated with TCF8 gene mutations and abdominal hernia

Mutations in the two-handed zinc-finger homeodomain transcription factor gene (TCF8) have been associated with posterior polymorphous corneal dystrophy (PPCD) and extraocular developmental abnormalities. We performed screening of TCF8 in 32 affected, unrelated probands, affected and unaffected family members of probands identified with a TCF8 mutation, and in 100 control individuals. Eight different pathogenic mutations were identified in eight probands: four frameshift (c.953_954insA, c.1506dupA, c.1592delA, and c.3012_3013delAG); three nonsense (Gln12X, Gln214X, Arg325X); and one missense (Met1Arg). Screening of TCF8 in affected and unaffected family members in six families demonstrated that each identified mutation segregated with the disease phenotype in each family; two probands did not have additional family members available for analysis. None of the eight TCF8 mutations was identified in 200 control chromosomes. The prevalence of hernias of the abdominal region in affected individuals with PPCD associated with TCF8 mutations was significantly higher than the prevalence in both individuals with PPCD not associated with a TCF8 mutation and in unaffected individuals. Therefore, PPCD is associated with TCF8 mutations in one quarter of affected families in this study, or about one third of all PPCD families that have been screened thus far. In these families, the presence of apparently causative TCF8 mutations is associated with abdominal and inguinal hernias.

The zinc finger transcription factor ZFHX1A is linked to cell proliferation by Rb-E2F1

ZFHX1A is expressed in proliferating cells in the developing embryo, and in the present study we provide evidence that its expression is confined to proliferating cells through dependence on the Rb (retinoblastoma protein) family/E2F cell cycle pathway. Mutation of the Rb or E2F1 genes lead to induction of ZFHX1A mRNA, implying that the Rb-E2F1 repressor complex is important for repression of ZFHX1A. This repression is associated with recruitment of an E2F-Rb-histone deacetylase repressor complex to the promoter. A dominant-negative form of E2F1 inhibited ZFHX1A expression in p16INK4a- cells where Rb is constitutively hyperphosphorylated and inactive, suggesting that E2F can contribute to ZFHX1A transactivation in the absence of functional Rb. ZFHX1A is an E-box-binding transcription factor whose binding sites overlap with those bound by Snail1 and 2, and ZFHX1B/SIP1 (leading to at least partially overlapping function; for example, each of the proteins can repress E-cadherin expression). We found that expression of Snail1 and ZFHX1B/SIP1 is also regulated by E2Fs, but in contrast with ZFHX1A this regulation is Rb-family-independent. Snail2 expression was unaffected by either E2F or the Rb family. We propose that the differential effects of the Rb family/E2F pathway on expression of these E-box-binding proteins are important in maintaining their distinct patterns (and thus distinct functions) during embryogenesis.

deltaEF1 represses BMP-2-induced differentiation of C2C12 myoblasts into the osteoblast lineage

Osteoblasts, derived from pluripotent mesenchymal precursor cells, acquire their differentiated phenotypes under the control of a series of regulatory factors, the best known of which is BMP-2. Our recent preliminary studies suggest that expression of deltaEF1, a member of the zinc finger-homeodomain transcription factor family, is significantly down-regulated as human mesenchymal stem cells (MSCs) are subjected to osteoblastic differentiation in the presence of BMP-2. Here we demonstrate that overexpression of deltaEF1 in murine pre-myoblast C2C12 cells resulted in a decrease in the mRNA levels of early osteoblast marker genes induced by BMP-2 including osterix and collagen type I. This inhibitory effect was further confirmed by decreased alkaline phosphatase (ALP) activities. Neither of the zinc finger clusters of deltaEF1 is necessary for its repressive effect on BMP-2-induced osteoblastic differentiation of C2C12 cells. Immunoprecipitation results indicated that deltaEF1 did not physically associate with Smads proteins, suggesting that the inhibitory effect of deltaEF1 may be Smad-independent. deltaEF1 overexpression in C2C12 cells resulted in down-regulation of activating protein-1 (AP-1) activities promoted by BMP-2. Moreover, deltaEF1 exhibited transrepression on murine osteocalcin gene which effect is partially mediated through diminishing of AP-1 signaling. These results suggest that deltaEF1 acts as a potent inhibitor of BMP-2-induced osteogenesis in vitro, in part, by differentially regulating the AP-1 signaling pathway.

MicroRNA-192 in diabetic kidney glomeruli and its function in TGF-beta-induced collagen expression via inhibition of E-box repressors

Key features of diabetic nephropathy (DN) include the accumulation of extracellular matrix proteins such as collagen 1-alpha 1 and -2 (Col1a1 and -2). Transforming growth factor beta1 (TGF-beta), a key regulator of these extracellular matrix genes, is increased in mesangial cells (MC) in DN. By microarray profiling, we noted that TGF-beta increased Col1a2 mRNA in mouse MC (MMC) but also decreased mRNA levels of an E-box repressor, deltaEF1. TGF-beta treatment or short hairpin RNAs targeting deltaEF1 increased enhancer activity of upstream E-box elements in the Col1a2 gene. TGF-beta also decreased the expression of Smad-interacting protein 1 (SIP1), another E-box repressor similar to deltaEF1. Interestingly, we noted that SIP1 is a target of microRNA-192 (miR-192), a key miR highly expressed in the kidney. miR-192 levels also were increased by TGF-beta in MMC. TGF-beta treatment or transfection with miR-192 decreased endogenous SIP1 expression as well as reporter activity of a SIP1 3' UTR-containing luciferase construct in MMC. Conversely, a miR-192 inhibitor enhanced the luciferase activity, confirming SIP1 to be a miR-192 target. Furthermore, miR-192 synergized with deltaEF1 short hairpin RNAs to increase Col1a2 E-box-luc activity. Importantly, the in vivo relevance was noted by the observation that miR-192 levels were enhanced significantly in glomeruli isolated from streptozotocin-injected diabetic mice as well as diabetic db/db mice relative to corresponding nondiabetic controls, in parallel with increased TGF-beta and Col1a2 levels. These results uncover a role for miRs in the kidney and DN in controlling TGF-beta-induced Col1a2 expression by down-regulating E-box repressors.

The Effects of Histone Deacetylase Inhibitors on the Induction of Differentiation in Chondrosarcoma Cells

PURPOSE

Histologically, chondrosarcomas represent the degree of chondrogenic differentiation, which is associated with the prognosis of the disease. Histone acetylation and deacetylation play key roles in the regulation of chondrocytic differentiation. Here, we describe the antitumor effects of histone deacetylase (HDAC) inhibitors as differentiating reagents on chondrosarcomas.

EXPERIMENTAL DESIGN

We examined the effects of a HDAC inhibitor, depsipeptide, on the growth of chondrosarcoma cell lines. We also investigated the modulation of the expression levels of extracellular matrix genes and the induction of phenotypic change in chondrosarcoma cells treated with depsipeptide. Finally, we examined the antitumor effect of depsipeptide on chondrosarcoma in vivo.

RESULTS

Depsipeptide inhibited the growth of chondrosarcoma cells by inducing cell cycle arrest and/or apoptosis. HDAC inhibitors increased the expression of the alpha1 chain of type II collagen (COL2A1) gene due to the enhanced histone acetylation in the promoter and enhancer. Depsipeptide also up-regulated the expressions of aggrecan and the alpha2 chain of type XI collagen (COL11A2) mRNA in a dose-dependent manner. Moreover, long-term treatment with a low dose of depsipeptide resulted in the induction of differentiation into hypertrophic phenotype, as shown by the increment of the alpha1 chain of type X collagen (COL10A1) expression in chondrosarcoma cells. In vivo studies and histologic analyses confirmed that depsipeptide significantly inhibited tumor growth and induced differentiation into the hypertrophic and mineralized state in chondrosarcoma cells.

CONCLUSIONS

These results strongly suggest that HDAC inhibitors may be promising reagents for use as a differentiating chemotherapy against chondrosarcomas.

The expression levels of the transcriptional regulators p300 and CtBP modulate the correlations between SNAIL, ZEB1, E-cadherin and vitamin D receptor in human colon carcinomas

ZEB1 and SNAIL repress CDH1 and induce epithelial-mesenchymal transition (EMT). However, SNAIL and ZEB1 also activate or regulate other target genes in different ways. For instance, vitamin D receptor (VDR), which activates CDH1 expression upon ligand binding, is repressed by SNAIL but induced by ZEB1. We examined whether the biological activity of SNAIL and ZEB1 in colon cancer is regulated by interacting cofactors. The mRNA expression levels of SNAIL and ZEB1, and of transcriptional regulators p300 and CtBP, were measured by RT-PCR in tumor and normal tissue from 101 colon carcinoma patients. Overexpression of SNAIL was associated with down-regulation of CDH1 and VDR (p = 0.004 and p < 0.001). CDH1 correlated with VDR (r = 0.49; p < 0.001). ZEB1 expression also correlated with VDR (r = 0.23; p = 0.019). However, when CtBP was strongly expressed, ZEB1 was inversely correlated with CDH1 (r = -0.39; p = 0.053). Furthermore, when there were elevated p300 expression levels, the correlation between expression of ZEB1 and VDR was stronger (r = 0.38; p = 0.070). Association between SNAIL expression and down-regulation of CDH1 and VDR was lost in tumors in which p300 and CtBP were strongly expressed. These results indicate that the levels of expression of CtBP and p300 are critical for the action of SNAIL and ZEB1, which have a pivotal role in EMT, and show the importance of CtBP and p300 for tumor progression.

A promoter element of the CD-RAP gene is required for repression of gene expression in non-cartilage tissues in vitro and in vivo

The cartilage-derived retinoic acid-sensitive protein (CD-RAP) gene is expressed predominately in cartilage. Previous studies in transgenic mice have shown that the DNA promoter segment from -2,251 bp to -2,068 bp of the CD-RAP gene contains elements critical for gene expression. Subsequent studies revealed both positive and negative regulatory motifs in this 183 bp element. Here we show that this element demonstrates activation or repression of gene expression in vitro and in vivo based on cell type and content of transcription factors. The distribution of Sox (positive) and C/EBP (negative) transcription factors in cell lines and in mouse tissues is consistent with their positive and negative roles. In transgenic mice, when the 183-bp element was removed from a 3,345-bp cartilage-specific CD-RAP promoter, expression of the reporter gene became widespread, being observed in muscle, bone, lung, and liver in addition to cartilage. In vitro, mutation of the C/EBP site activated the inactive 3,345-bp CD-RAP gene promoter in myoblastic cells, suggesting that this site is responsible for (-2,079 bp) repression. These results indicate that the 183-bp element plays an important role in cartilage-specific gene expression by acting as a chondrocyte-regulatory module repressing transcription in non-chondrocytes and contributing to activation in chondrocytes. This is the first report of a functional DNA element necessary for repression in non-cartilage tissues in vivo.

The transcription factor ZEB1 is aberrantly expressed in aggressive uterine cancers

The transcription factor ZEB1 (deltaEF1 in mice) has been implicated in cellular processes during development and tumor progression including epithelial to mesenchymal transition. deltaEF1 null mice die at birth, but heterozygotes expressing a LacZ reporter inserted into the deltaEF1 gene live and reproduce. Using these mice, we observed ZEB1 promoter activity in the virgin myometrium, and stroma and myometrium of the pregnant uterus. ZEB1 protein is up-regulated in the myometrium and endometrial stroma after progesterone or estrogen treatment of ovariectomized mice. In the normal human uterus, ZEB1 protein is increased in the myometrium and stroma during the secretory stage of the menstrual cycle. ZEB1 is not expressed in the normal endometrial epithelium. In malignancies of the uterus, we find that ZEB1 (a) is overexpressed in malignant tumors derived from the myometrium (leiomyosarcomas), (b) is overexpressed in tumor-associated stroma of low-grade endometrioid adenocarcinomas, and (c) is aberrantly expressed in the tumor epithelial cells of aggressive endometrial cancers. Specifically, in grade 3 endometrioid adenocarcinomas and uterine papillary serous carcinomas, ZEB1 could be expressed in the epithelial-derived carcinoma cells as well as in the stroma. In malignant mixed Müllerian tumors, the sarcomatous component always expresses ZEB1, and the carcinomatous component can also be positive. In summary, ZEB1 is normally regulated by both estrogen and progesterone receptors, but in uterine cancers, it is likely no longer under control of steroid hormone receptors and becomes aberrantly expressed in epithelial-derived tumor cells, supporting a role for ZEB1 in epithelial to mesenchymal transitions associated with aggressive tumors.

Intrajoint comparisons of gene expression patterns in human osteoarthritis suggest a change in chondrocyte phenotype

Osteoarthritis (OA) is a degenerative cartilage disease with varying degrees of severity within a given joint. The purpose of this study was to define a sampling procedure for comparing human minimal and advanced OA cartilage in the same patient and to determine basic patterns of gene expression in these regions. A specific hypothesis under study was that the expression level of Bcl-2 would correlate with Sox9 and aggrecan mRNA expression in vivo as has been demonstrated in vitro. Femoral condylar advanced OA cartilage was located within 1cm of overt lesions, and minimal cartilage was taken from areas with no obvious surface defects. Histological sections were scored for disease severity and chondroitin sulfate and hydroxyproline content was determined. The expression level of nine specific genes (aggrecan, collagen type II, Bcl-2, Sox9, Link protein, osteopontin, and MMP-13, -3, and -9) was determined by quantitative real time PCR. The scores for fibrillation, chondrocyte cloning, and proteoglycan depletion were significantly different between advanced and minimal OA cartilage. The advanced OA cartilage had significantly less chondroitin sulfate than the minimal OA cartilage. Osteopontin mRNA expression showed a 3.6-fold increase in advanced compared to minimal OA cartilage. In contrast, the level of mRNA coding for aggrecan, link protein, Bcl-2, Sox9 and MMP-3, -9, -13 were all decreased in advanced compared to minimal cartilage in the majority of the patients studied. Collagen type II mRNA expression displayed a wide-range of variation. A statistically significant correlation was observed both between Bcl-2 and Sox9 mRNA level, and between Bcl-2 and aggrecan mRNA expression. The patient matched comparison of minimal and advanced OA cartilage revealed differences in cellular and tissue characteristics, and changes in gene expression that may be involved in OA progression. In addition, Bcl-2 may also play a role in regulating the expression of aggrecan through Sox9 in vivo as well as in vitro.

APBP-1, a DNA/RNA-binding protein, interacts with the chick aggrecan regulatory region

Expression of the extracellular proteoglycan aggrecan is both cell-specific and developmentally regulated. Previous studies identified six functionally defined cis elements in the aggrecan promoter region which were shown to repress aggrecan gene expression (1). Using competition electrophoretic mobility shift assays (EMSAs) we have now identified in nuclear extracts a functional repressor cis element, (T/C)TCCCCT(A/C)RRC, which occurs at multiple locations within the chick aggrecan regulatory region. We purified the factor that binds to this cis element and established that it, APBP-1 (aggrecan promoter-binding protein-1), is a 19-kDa protein that has significant homology to CIRP (cold inducible RNA-binding protein). Recombinantly expressed APBP-1 mimics the native cis element-trans factor interaction in EMSAs. In situ hybridization demonstrates that aggrecan and APBP-1 RNA expression are restricted to complementary tissues in the developing limb, and Northern blot analysis of chick limb bud mRNA shows that APBP-1 mRNA expression is inversely correlated with aggrecan mRNA expression. Functional analyses by transient transfections and Northern blot analyses suggest APBP-1 has the capacity to repress aggrecan expression, indicating that this factor may be important regulator of aggrecan gene expression.

The homeobox transcription factor Barx2 regulates chondrogenesis during limb development

Among the many factors involved in regulation of chondrogenesis, bone morphogenetic proteins (BMPs) and members of the Sox and homeobox transcription factor families have been shown to have crucial roles. Of these regulators, the homeobox transcription factors that function during chondrogenesis have been the least well defined. We show here that the homeobox transcription factor Barx2 is expressed in primary mesenchymal condensations, digital rays, developing joints and articular cartilage of the developing limb, suggesting that it plays a role in chondrogenesis. Using retroviruses and antisense oligonucleotides to manipulate Barx2 expression in limb bud micromass cultures, we determined that Barx2 is necessary for mesenchymal aggregation and chondrogenic differentiation. In accordance with these findings, Barx2 regulates the expression of several genes encoding cell-adhesion molecules and extracellular matrix proteins, including NCAM and collagen II (Col2a1) in the limb bud. Barx2 bound to elements within the cartilage-specific Col2a1 enhancer, and this binding was reduced by addition of Barx2 or Sox9 antibodies, or by mutation of a HMG box adjacent to the Barx2-binding element, suggesting cooperation between Barx2 and Sox proteins. Moreover, both Barx2 and Sox9 occupy Col2a1 enhancer during chondrogenesis in vivo. We also found that two members of the BMP family that are crucial for chondrogenesis, GDF5 and BMP4, regulate the pattern of Barx2 expression in developing limbs. Based on these data, we suggest that Barx2 acts downstream of BMP signaling and in concert with Sox proteins to regulate chondrogenesis.

Identification of alternative promoter usage for the matrix Gla protein gene. Evidence for differential expression during early development in Xenopus laevis

Recent cloning of the Xenopus laevis (Xl) matrix Gla protein (MGP) gene indicated the presence of a conserved overall structure for this gene between mammals and amphibians but identified an additional 5'-exon, not detected in mammals, flanked by a functional, calcium-sensitive promoter, 3042 bp distant from the ATG initiation codon. DNA sequence analysis identified a second TATA-like DNA motif located at the 3' end of intron 1 and adjacent to the ATG-containing second exon. This putative proximal promoter was found to direct transcription of the luciferase reporter gene in the X. laevis A6 cell line, a result confirmed by subsequent deletion mutant analysis. RT-PCR analysis of XlMGP gene expression during early development identified a different temporal expression of the two transcripts, strongly suggesting differential promoter activation under the control of either maternally inherited or developmentally induced regulatory factors. Our results provide further evidence of the usefulness of nonmammalian model systems to elucidate the complex regulation of MGP gene transcription and raise the possibility that a similar mechanism of regulation may also exist in mammals.

Transcriptional Co-activators CREB-binding protein/p300 increase chondrocyte Cd-rap gene expression by multiple mechanisms including sequestration of the repressor CCAAT/enhancer-binding protein

Cartilage-derived retinoic acid-sensitive protein (CD-RAP) is a small secreted matrix protein expressed in developing and adult cartilage and by chondrocytes in culture. We have previously shown that the expression of Cd-rap, like many other cartilage matrix proteins, is repressed by interleukin 1beta and that the transcription factor CCAAT/enhancer-binding protein (C/EBP) beta plays an important role in the interleukin 1beta-induced repression (Okazaki, K., Li, J., Yu, H., Fukui, N., and Sandell, L. J. (2002) J. Biol. Chem. 277, 31526-31533). The co-activators CREB-binding protein (CBP) and p300 are transcriptional co-regulators that participate in the activities of many different transcription factors including C/EBP. Here we show that CBP/p300 can reverse the inhibitory effect of C/EBP and moreover can stimulate expression of Cd-rap. The mechanism of this effect is shown to involve a unique synergy whereby CBP/p300 stimulate Cd-rap gene expression by at least two mechanisms. First, binding of CBP/p300 to C/EBPbeta leads to sequestration of C/EBP eliminating DNA binding and subsequent repression; second, binding of CBP/p300 to the transcriptional activator Sox9 increases Sox9 DNA binding to the Cd-rap promoter leading to further stimulation of gene transcription. This is an example of a complementary transcriptional network whereby two very different mechanisms act together to confer a functional increase in transcription. This new paradigm is likely generally applicable to cartilage genes as Col2a1 cartilage collagen gene responds similarly.

Extracellular matrix gene regulation

Extracellular matrix metabolism plays a central role in development of skeletal tissues and in most orthopaedic diseases and trauma such as fracture or osteotomy repair, arthritis, cartilage repair, and congenital skeletal deformity. During development or disease, specific genes must be expressed in order to make or repair appropriate extracellular matrix. For example, specific gene expression patterns are characteristic of bone and cartilage. The precise expression pattern depends on a balance of positive and negative transcription factors, proteins that control the synthesis of mRNA from the specific gene. In cartilage, a number of studies indicate that Sox transcription factors are critical positive regulators in genes such as COL2A1, COL9A2, COL11A2, aggrecan, and CD-RAP. In addition, negative regulators are also essential to fine tune gene regulation in chondrocytes and to turn off gene expression in noncartilaginous tissues. Negative transcription factors in cartilage include partial differentialEF-1, snail/slug, CYRBP1, NT2, and C/EBP. Runx2 and osterix are critical transcription factors for osteogenesis but also have some influence on chondrogenesis. The availability of cis-regulatory sites in specific genes combined with the availability of transcription factors in the nucleus determines the level of gene expression.

Expression of Zfhep/deltaEF1 protein in palate, neural progenitors, and differentiated neurons

Zfhep/deltaEF1 is essential for embryonic development. We have investigated the expression pattern of Zfhep protein during mouse embryogenesis. We show expression of Zfhep in the mesenchyme of the palatal shelves, establishing concordance of expression with the reported cleft palate of the deltaEF1-null mice. Zfhep protein is strongly expressed in proliferating progenitors of the nervous system. In most regions of the brain, post-mitotic cells stop expressing Zfhep when they migrate out of the ventricular zone (VZ) and differentiate. However, in the hindbrain, Zfhep protein is also highly expressed in post-mitotic migratory neuronal cells of the precerebellar extramural stream that arise from the neuroepithelium adjacent to the lower rhombic lip. Also, Zfhep is expressed as cells migrate from a narrow region of the pons VZ towards the trigeminal nucleus. Co-expression with Islet1 shows that Zfhep is expressed in motor neurons of the trigeminal nucleus of the pons, but not in the inferior olive motor neurons at E12.5. Therefore, Zfhep is strongly expressed in a tightly regulated pattern in proliferating neural stem cells and a subset of neurons. Zfhep protein is also strongly expressed in trigeminal ganglia, and is moderately expressed in other cranial ganglia. In vitro studies have implicated Zfhep as a repressor of myogenesis, however, we find that Zfhep protein expression increases during muscle differentiation.

Regulation of collagen type I in vascular smooth muscle cells by competition between Nkx2.5 and deltaEF1/ZEB1

A major component of the vessel wall of large arteries and veins is the extracellular matrix (ECM), which consists of collagens, elastin, and proteoglycans. Collagen type I is one of the most abundant of the ECM proteins. We have previously shown that the pro-collagen type I alpha 2 gene contains an enhancer which confers tissue-specific expression in the majority of collagen-producing cells, including blood vessels. In this paper, we delineate a specific vascular smooth muscle cell (vSMC) element: a 100-bp sequence around -16.6 kb upstream of the transcription start site that regulates collagen expression exclusively in vSMCs. Furthermore, we show that the expression is activated through the binding of the homeodomain protein Nkx2.5, which is further potentiated in the presence of GATA6. In contrast, this element was repressed by the binding of the zinc-finger protein deltaEF1/ZEB1. We propose a model of regulation where the activating transcription factor Nkx2.5 and the repressor deltaEF1/ZEB1 compete for an overlapping DNA binding site. This element is important in understanding the molecular mechanisms of vessel remodeling and is a potential target for intervention in vascular diseases where there is excessive deposition of collagen in the vessel wall.

Characterization and chondrocyte differentiation stage-specific expression of KRAB zinc-finger protein gene ZNF470

As part of a study to identify novel transcriptional regulators of chondrogenesis-related gene expression, we have cloned and characterized cDNA for zinc-finger protein 470 (ZNF470), the human ortholog of which encodes a 717 amino acid residue protein containing 17 Cys(2)His(2) zinc-finger domains, as well as KRAB-A and KRAB-B motifs. The cDNA library used to isolate the initial ZNF470 clone was prepared from human bone marrow-derived mesenchymal progenitor cells at an intermediate stage of chondrogenic differentiation. We have determined the intron-exon structure of the human ZNF470 gene, which has been mapped to a zinc-finger cluster in a known imprinted region of human chromosome 19q13.4. ZNF470 is expressed at high levels in human testis and is expressed at low or undetectible levels in other adult tissues. Human ZNF470 expressed in mammalian cells as an EGFP fusion protein localizes predominantly to the nucleus, consistent with a role in transcriptional regulation. ZNF470, analyzed by quantitative real time PCR, was transiently expressed before the maximal expression of COL2A1 during chondrogenic differentiation in vitro. We have also characterized the bovine ortholog of human ZNF470, which encodes a 508 amino acid residue protein having 10 zinc-finger domains. A bovine ZNF470 cDNA clone was used to examine expression of ZNF470 in bovine articular chondrocytes treated with retinoic acid to stimulate dedifferentiation. Bovine ZNF470 expression was undetectable in freshly isolated bovine articular chondrocytes, but was dramatically upregulated in dedifferentiated retinoic acid-treated chondrocytes. These results, in two model systems, suggest a possible role for ZNF470 in the regulation of chondrogenesis-specific gene expression.

The transcription factor CCAAT-binding factor CBF/NF-Y and two repressors regulate the core promoter of the human pro-alpha3(V) collagen gene (COL5A3)

To elucidate the mechanisms underlining alpha3(V) collagen chain expression, we performed an initial analysis of the structure and function of the core promoter of the human COL5A3 gene. The core promoter, which lacks a typical TATA motif and has a high GC content, was defined within the -129 bp immediately upstream from the major transcription start site by transient transfection experiments. In this region, we identified four DNA-protein complexes, named A, B, C, and D, by a combination of DNase I footprinting and electrophoretic mobility shift assays. Electrophoretic mobility shift assays using mutant oligonucleotide revealed that the complexes A, B, C, and D bind to -122 to -117, the -101 to -96, the -83 to -78, and the -68 to -57 bp, respectively. The competition assays using consensus oligonucleotides and supershift assays with specific antibodies showed that complex A consists of CBF/NF-Y. In a chromatin immunoprecipitation assay, CBF/NF-Y protein directly bound to this region, in vivo. Functional analysis showed that CBF/NF-Y activated the gene, whereas the proteins of complexes B and C repressed its activity. Furthermore, overexpression of a mutant form of the CBF-B/NF-YA subunit, which forms CBF/NF-Y with CBF-A/NF-YB and CBF-C/NF-YC subunits, inhibited promoter activity.

A silencer element in the cartilage oligomeric matrix protein gene regulates chondrocyte-specific expression

The molecular mechanisms by which mesenchymal cells differentiate into chondrocytes are poorly understood. The cartilage oligomeric matrix protein gene (COMP) encodes a noncollagenous extracellular matrix protein whose expression pattern correlates with chondrocyte differentiation and arthritis. We have used the COMP promoter as a model to identify regulatory sequences necessary for chondrocyte-specific expression and to identify cell type-specific proteins that bind these sequences. We have previously cloned 1.9 kilobases of the 5(') flanking promoter sequence of the murine COMP gene and by deletion analysis have identified two spatially distant chondrocyte-specific regulatory regions. One element is situated proximally (-125 to -75), and a second region is located distally (-1925 to -592) relative to the transcription start site. In the present study, we performed a finer deletion analysis of the region of the COMP promoter from -1925 to -592 and identified a silencer region situated between -1775 and -1725. This silencer binds sequence-specific protein complexes; the intensity of these complexes is greater in two different fibroblast cell lines (NIH3T3 and 10T1/2) than in chondrocytic RCS cells. Competition experiments localized the binding site of these protein complexes from -1775 to -1746; deletion of this 30-bp site results in a selective increase in COMP promoter activity in fibroblasts. Four tandem repeats of this 30-bp site are sufficient to confer negative transcriptional regulation on a heterologous promoter (SV40) in NIH3T3 fibroblasts. These results suggest that negative regulation of transcription is an important mechanism for chondrocyte-specific expression of the COMP gene.