Cloning of the human homologue of the TGF beta-stimulated clone 22 gene

Overexpression of TSC-22 (transforming growth factor- β-stimulated clone-22) causes marked obesity, splenic abnormality and B cell lymphoma in transgenic mice

In this study, we generated transgenic (Tg) mice, which overexpressed transforming growth factor (TGF)-β stimulated clone-22 (TSC-22), and investigate the functional role of TSC-22 on their development and pathogenesis. We obtained 13 Tg-founders (two mice from C57BL6/J and 11 mice from BDF1). Three of 13 Tg-founders were sterile, and the remaining Tg-founders also could generate only a limited number of the F1 generation. We obtained 32 Tg-F1 mice. Most of the Tg-mice showed marked obesity. Histopathological examination could be performed on 31 Tg-mice; seventeen mice died by some disease in their entire life and 14 mice were killed for examination. Most of the Tg-mice examined showed splenic abnormality, in which marked increase of the megakaryocytes, unclearness of the margin of the red pulp and the white pulp, and the enlargement of the white pulp was observed. B cell lymphoma was developed in 10 (71%) of 14 disease-died F1 mice. These results indicate that constitutive over-expression of TSC-22 might disturb the normal embryogenesis and the normal lipid metabolism, and induce the oncogenic differentiation of hematopoietic cells.

TSC-22 Promotes Interleukin-2-Deprivation Induced Apoptosis in T-Lymphocytes

Originally described as a TGF-β-inducible gene, tsc-22 (Transforming growth factor-beta Stimulated Clone 22) encodes a transcriptional regulator affecting biological processes such as cell growth, differentiation, or apoptosis. Along with GILZ (Glucocorticoid-Induced Leucine Zipper), TSC-22 belongs to the evolutionary conserved TSC-22 Domain family. We previously showed that, in T-lymphocytes, GILZ expression was induced upon IL-2 withdrawal, delaying apoptosis through down-regulation of the pro-apoptotic protein BIM expression. The aim of this work was then to elucidate the respective roles of GILZ and TSC-22 upon IL-2 deprivation-induced apoptosis. We report here that these two highly homologous genes are concomitantly expressed in most human tissues and in primary T-lymphocytes and that expression of TSC-22 promotes T-lymphocytes apoptosis by inhibiting GILZ functions. Indeed, we demonstrated that TSC-22 expression in the murine lymphoid CTLL-2 cell line promoted IL-2 deprivation-induced apoptosis. BIM expression and caspases-9 and -3 activities were markedly increased in TSC-22 expressing clones compared to control clones. Analysis of GILZ expression revealed that TSC-22 prevented the induction of the GILZ protein upon IL-2 deprivation, by inhibiting gilz mRNA transcription. These results suggested that TSC-22 could counteract the protective effect of GILZ on IL-2-deprivation-induced apoptosis. Moreover, TSC-22-induced inhibition of GILZ expression was also found in CTLL-2 cells treated with glucocorticoids or TGF-β. In the human NKL cell line deprived of IL-2, TSC-22 showed the same effect and thus may represent a potent repressor of GILZ expression in IL-2-dependent cells, independently of the cell type, or the stimulus, leading to an increase of IL-2-deprived T-cells apoptosis. J. Cell. Biochem. 117: 1855-1868, 2016. © 2016 Wiley Periodicals, Inc.

Nuclear receptor binding protein 1 regulates intestinal progenitor cell homeostasis and tumour formation

Genetic screens in simple model organisms have identified many of the key components of the conserved signal transduction pathways that are oncogenic when misregulated. Here, we identify H37N21.1 as a gene that regulates vulval induction in let-60(n1046gf), a strain with a gain-of-function mutation in the Caenorhabditis elegans Ras orthologue, and show that somatic deletion of Nrbp1, the mouse orthologue of this gene, results in an intestinal progenitor cell phenotype that leads to profound changes in the proliferation and differentiation of all intestinal cell lineages. We show that Nrbp1 interacts with key components of the ubiquitination machinery and that loss of Nrbp1 in the intestine results in the accumulation of Sall4, a key mediator of stem cell fate, and of Tsc22d2. We also reveal that somatic loss of Nrbp1 results in tumourigenesis, with haematological and intestinal tumours predominating, and that nuclear receptor binding protein 1 (NRBP1) is downregulated in a range of human tumours, where low expression correlates with a poor prognosis. Thus NRBP1 is a conserved regulator of cell fate, that plays an important role in tumour suppression.

Differential gene expression analysis in fracture callus of patients with regular and failed bone healing

OBJECTIVE

Although several systemic and local factors are known to impair fracture healing, there is still no explanation, why some patients with sufficient fracture stability, showing none of the existing risk factors, still fail to heal normally. An investigation of local gene expression patterns in the fracture gap of patients with non-unions could decisively contribute to a better understanding of the pathophysiology of impaired fracture healing. For the first time, this study compares the expression of a large variety of osteogenic and chondrogenic genes in patients with regular and failed fracture healing.

METHODS

Between March 2006 and May 2007, a total of 130 patients who were surgically treated at the Berufsgenossenschaftliche Unfallklink Ludwigshafen were screened for the study. Tissue samples of patients with normal and failed fracture healing were collected intraoperatively. Patients were divided into groups depending on the fracture date, and only patients with fractures two to four weeks old and patients with non-unions more than 9 months old were included in the final analysis. For the gene expression analysis, a customised cDNA array - containing 226 genes involved in osteo- and chondrogenesis - was used.

RESULTS

In the cDNA array analysis, the expression of eight genes was significantly elevated two-fold or more in the group with failed fracture healing relative to the normal controls. Conversely, no genes were found to be expressed at a higher level in the control group. The identified genes are supposed to be involved in extracellular matrix assembly, cytoskeletal structure, and differentiative and proliferative processes.

CONCLUSIONS

The differences in gene expression pattern indicate a change in the composition and structure of the extracellular matrix, and a possible turn in the healing programme towards fibrous scar tissue formation, leading to non-union.

Transforming growth factor-β-stimulated clone-22 is a negative-feedback regulator of Ras / Raf signaling: Implications for tumorigenesis

Transforming growth factor-β (TGF-β)-stimulated clone-22 (TSC-22), also called TSC22D1-2, is a putative tumor suppressor. We previously identified TSC-22 downstream of an active mutant of fms-like tyrosine kinase-3 (Flt3). Here, we show that TSC-22 works as a tumor suppressor through inhibiting Ras/Raf signaling. Notably, TSC-22 was upregulated by Ras/Raf activation, whereas its upregulation was inhibited by concurrent STAT5 activation. Although TSC-22 was normally retained in the cytoplasm by its nuclear export signal (NES), Ras/Raf activation caused nuclear translocation of TSC-22, but not TSC22D1-1. Unlike glucocorticoid-induced leucine zipper (GILZ/TSC22D3-2) previously characterized as a negative regulator of Ras/Raf signaling, TSC-22 failed to interact physically with Ras/Raf. Importantly, transduction with TSC-22, but not TSC22D1-1, suppressed the growth, transformation and tumorigenesis of NIH3T3 cells expressing oncogenic H-Ras: this suppression was enhanced by transduction with a TSC-22 mutant lacking NES that had accumulated in the nucleus. Collectively, upregulation and nuclear translocation of TSC-22 played an important role in the feedback suppression of Ras/Raf signaling. Consistently, TSC22D1-deficient mice were susceptible to tumorigenesis in a mouse model of chemically-induced liver tumors bearing active mutations of Ras/Raf. Thus, TSC-22 negatively regulated Ras/Raf signaling through a mechanism different from GILZ, implicating TSC-22 as a novel suppressor of oncogenic Ras/Raf-induced tumors.

TSC-22 promotes transforming growth factor β-mediated cardiac myofibroblast differentiation by antagonizing Smad7 activity

Transforming growth factor β (TGF-β) plays a critical role in tissue fibrosis. The duration and intensity of TGF-β signaling are tightly regulated. Here we report that TSC-22 (TGF-β-stimulated clone 22) facilitates TGF-β signaling by antagonizing Smad7 activity to increase receptor stability. TSC-22 enhances TGF-β-induced Smad2/3 phosphorylation and transcriptional responsiveness. The stimulatory effect of TSC-22 is dependent on Smad7, as silencing Smad7 expression abolishes it. TSC-22 interacts with TGF-β type I receptor TβRI and Smad7 in mutually exclusive ways and disrupts the association of Smad7/Smurfs with TβRI, thereby preventing ubiquitination and degradation of the receptor. We also found that TSC-22 can promote the differentiation of cardiac myofibroblasts by increasing expression of the fibrotic genes for α-smooth muscle actin (α-SMA), PAI-1, fibronectin, and collagen I, which is consistent with upregulation of TSC-22, phospho-Smad2/3, and the fibrotic genes in isoproterenol-induced rat myocardial fibrotic hearts. Taken together with the notion that TGF-β induces TSC-22 expression, our findings suggest that TSC-22 regulates TGF-β signaling via a positive-feedback mechanism and may contribute to myocardial fibrosis.

TSC-22D1 isoforms have opposing roles in mammary epithelial cell survival

Transforming growth factor beta (TGFbeta)-stimulated clone-22 domain family member 1 (TSC-22D1) has previously been associated with enhanced apoptosis in several cell systems. In an attempt to identify novel factors that are involved in the control of cell death during mammary gland involution, we found that the mRNA for isoform 2 of TSC-22D1 was highly upregulated 24 h after forced weaning, when a dramatic increase in cell death occurred, closely following the expression of the known inducer of cell death during involution, TGFbeta3. This was paralleled by strongly increased TSC-22D1 isoform 2 protein levels in the luminal epithelium. In contrast, RNA and protein expression levels of the isoform 1 of TSC-22D1 did not change during development. Whereas isoform 2 induced cell death, isoform 1 suppressed TGFbeta-induced cell death and enhanced proliferation in mammary epithelial cell lines. Furthermore, four distinct forms of isoform 2 protein were detected in the mammary gland, of which only a 15-kDa form was associated with early involution. Our data describe novel opposing functions of the two mammalian TSC-22D1 isoforms in cell survival and proliferation, and establish the TSC-22D1 isoform 2 as a potential regulator of cell death during mammary gland involution.

TSC-22 contributes to hematopoietic precursor cell proliferation and repopulation and is epigenetically silenced in large granular lymphocyte leukemia

Aberrant methylation of tumor suppressor genes can lead to their silencing in many cancers. TSC-22 is a gene silenced in several solid tumors, but its function and the mechanism(s) responsible for its silencing are largely unknown. Here we demonstrate that the TSC-22 promoter is methylated in primary mouse T or natural killer (NK) large granular lymphocyte (LGL) leukemia and this is associated with down-regulation or silencing of TSC-22 expression. The TSC-22 deregulation was reversed in vivo by a 5-aza-2'-deoxycytidine therapy of T or NK LGL leukemia, which significantly increased survival of the mice bearing this disease. Ectopic expression of TSC-22 in mouse leukemia or lymphoma cell lines resulted in delayed in vivo tumor formation. Targeted disruption of TSC-22 in wild-type mice enhanced proliferation and in vivo repopulation efficiency of hematopoietic precursor cells (HPCs). Collectively, our data suggest that TSC-22 normally contributes to the regulation of HPC function and is a putative tumor suppressor gene that is hypermethylated and silenced in T or NK LGL leukemia.

A TSC22-like motif defines a novel antiapoptotic protein family

The apoptotic programme is evolutionarily conserved between yeast and metazoan organisms. We have previously identified a number of mammalian cDNAs capable of suppressing the deleterious effects of Bax expression in yeast. We herein report that one such suppressor, named Tsc22((86)), represents the C-terminal 86 amino acids of the previously characterized leucine zipper (LZ) motif-containing transcriptional regulator Tsc22. Employing a genome-wide two-hybrid screen, functional genomics, and deletion mutagenesis approaches, we conclude that Tsc22((86))-mediated antiapoptosis is independent of the LZ motif and is likely independent of effects on gene transcription. Rather, a 16-residue sequence within the conserved 56-residue TSC22 domain is necessary for antiapoptosis. The presence of a similar sequence was used to predict an antiapoptotic role for two yeast proteins, Sno1p and Fyv10p. Overexpression and knock-out experiments were used to validate this prediction. These findings demonstrate the potential of studying heterologous proteins in yeast to uncover novel biological insights into the regulation of apoptosis.

Interaction between fortilin and transforming growth factor-beta stimulated clone-22 (TSC-22) prevents apoptosis via the destabilization of TSC-22

Yeast two-hybrid screening was conducted using a human ovary cDNA library to search for a novel binding protein using transforming growth factor-beta stimulated clone-22 (TSC-22). The selected protein was fortilin, which has been characterized as a nuclear anti-apoptotic protein. Overexpression of fortilin in ovarian carcinoma cells reversed TSC-22-mediated apoptosis, and the inhibition of fortilin expression via small interfering RNA (siRNA) resulted in an increase in the apoptosis of ovarian carcinoma cells. Moreover, fortilin overexpression promoted the degradation of TSC-22. Thus, an interaction between fortilin and TSC-22 prevents apoptosis via the destabilization of TSC-22 in ovarian carcinoma cells.

Differential activities of glucocorticoid-induced leucine zipper protein isoforms

Glucocorticoid-induced leucine zipper protein (GILZ) is expressed in both epithelial and immune tissues and modulates a variety of cellular functions, including proliferation and epithelial sodium channel (ENaC) activity. A number of reports have described various GILZ activities, focusing on a single isoform with molecular mass of approximately 17 kDa, now termed GILZ1. In GILZ immunoblots using a newly developed antiserum, we detected multiple species in extracts from cultured kidney cells. Mass spectrometric analysis revealed that one of these represented a previously uncharacterized distinct isoform of GILZ, GILZ2. Rapid amplification of cDNA ends was used to clone cDNAs corresponding to four isoforms, which, in addition to GILZ1 and GILZ2, included new isoforms GILZ3 and GILZ4. Heterologous expression of these four GILZ isoforms in cultured cells revealed striking functional differences. Notably, GILZ1 was the only isoform that significantly stimulated ENaC-mediated Na+ current in a kidney collecting duct cell line, although GILZ2 and GILZ3 also stimulated ENaC surface expression in HEK 293 cells. GILZ1 and GILZ3, and to a lesser extent GILZ2, inhibited ERK phosphorylation. Interestingly, GILZ4, which had no effect on either ENaC or ERK, potently suppressed cellular proliferation, as did GILZ1, but not GILZ2 or GILZ3. Finally, rat and mouse tissues all expressed multiple GILZ species but varied in the relative abundance of each. These data suggest that multiple GILZ isoforms are expressed in most cells and tissues and that these play distinct roles in regulating key cellular functions, including proliferation and ion transport. Furthermore, GILZ inhibition of ERK appears to play an essential role in stimulation of cell surface ENaC but not in inhibition of proliferation.

Identification of TSC-22 as a potential tumor suppressor that is upregulated by Flt3-D835V but not Flt3-ITD

Transforming growth factor-beta (TGF-beta)-stimulated clone-22 (TSC-22) was originally isolated as a TGF-beta-inducible gene. In this study, we identified TSC-22 as a potential leukemia suppressor. Two types of FMS-like tyrosine kinase-3 (Flt3) mutations are frequently found in acute myeloid leukemia: Flt3-ITD harboring an internal tandem duplication in the juxtamembrane domain associated with poor prognosis and Flt3-TKD harboring a point mutation in the kinase domain. Comparison of gene expression profiles between Flt3-ITD- and Flt3-TKD-transduced Ba/F3 cells revealed that constitutive activation of Flt3 by Flt3-TKD, but not Flt3-ITD, upregulated the expression of TSC-22. Importantly, treatment with an Flt3 inhibitor PKC412 or an Flt3 small interfering RNA decreased the expression level of TSC-22 in Flt3-TKD-transduced cells. Forced expression of TSC-22 suppressed the growth and accelerated the differentiation of several leukemia cell lines into monocytes, in particular, in combination with differentiation-inducing reagents. On the other hand, a dominant-negative form of TSC-22 accelerated the growth of Flt3-TKD-transduced 32Dcl.3 cells. Collectively, these results suggest that TSC-22 is a possible target of leukemia therapy.

TGF-β1 and TSC-22 Gene Polymorphisms and Susceptibility to Microvascular Complications in Type 2 Diabetes

BACKGROUND/AIM

There is a strong evidence for the involvement of genetic factors in diabetic microvascular complications. The aim of our study was to investigate the role of molecular variants of the TGF-beta1 (transforming growth factor beta 1) and the TSC-22 (transforming growth factor beta stimulated clone 22) genes in diabetic nephropathy and diabetic retinopathy in type 2 diabetes.

METHODS

A case-control study was conducted in 503 patients and 400 healthy subjects. DNA samples were genotyped by polymerase chain reaction and restriction fragment length polymorphism methods.

RESULTS

Among the patients, 245 had diabetic nephropathy, 195 had retinopathy, and 168 were free from complications. All subjects were genotyped for T869C and C -509T polymorphisms of the TGF-beta1 gene and for -396 polymorphism of the TSC-22 gene. A significantly increased frequency of the CC genotype of the T869C polymorphism was observed in patients with nephropathy and retinopathy (33 and 48%, respectively, vs. 19 and 15%, respectively, in controls and patients free from complications). The frequency of the C allele was also higher (0.58 for nephropathy and 0.64 for retinopathy vs. 0.42 in controls). The G allele of the TSC-22 polymorphism was associated with an increased risk of diabetic nephropathy (frequency 0.15 vs. 0.07 and 0.06, respectively, in patients free from complications and controls). An interaction was observed between the G allele of the TSC-22 polymorphism and the C-allele of the TGF-beta polymorphism.

CONCLUSIONS

Our data suggest the association of TGF-beta T869C gene polymorphism with an increased risk of nephropathy and retinopathy in type 2 diabetes patients. It interacts with the TSC-22 gene involved in the TGF-beta signaling pathway, promoting the development of diabetic nephropathy.

Chemical genetic transcriptional fingerprinting for selectivity profiling of kinase inhibitors

The importance of protein kinases as a major class of drug targets across multiple diseases has generated a critical need for technologies that enable the identification of potent and selective kinase inhibitors. Bruton's tyrosine kinase (Btk) is a compelling drug target in multiple therapeutic areas, including systemic lupus erythematosus, asthma, rheumatoid arthritis, and B cell malignancies. We have combined potent, selective kinase inhibition through chemical genetics with gene expression profiling to identify a "fingerprint" of transcriptional changes associated with selective Btk kinase inhibition. The Btk transcriptional fingerprint shows remarkable relevance for Btk's biological roles and was used for functional selectivity profiling of two kinase inhibitor compounds. The fingerprint was able to rank the compounds by relative selectivity for Btk, and revealed broader off-target effects than observed in a broad panel of biochemical kinase cross screens. In addition to being useful for functional selectivity profiling, the fingerprint genes are themselves potential preclinical and clinical biomarkers for developing Btk-directed therapies.

CD133-positive hematopoietic stem cell "stemness" genes contain many genes mutated or abnormally expressed in leukemia

Affymetrix human Hu133A oligonucleotide arrays were used to study the expression profile of CD133+ cord blood (CB) and peripheral blood (PB) using CD133 cell-surface marker. An unsupervised hierarchical clustering of 14,025 valid probe sets showed a clear distinction between the CD133+ cells representing the hematopoietic stem cell (HSC) population and CD133-differentiated cells. Two hundred forty-four genes were found to be upregulated by at least twofold in the CD133-positive cells of both CB and PB compared with the CD133-negative cells. These genes represent the hematopoietic "stemness," whereas the 218 and 304 upregulated genes exclusively in PB and CB, respectively, represent tissue specificity. Some of the stemness genes were also common to HSC genes found to be upregulated in several recently published studies. Among these common stemness genes, we identified several groups of genes that have an important role in hematopoiesis: growth factor receptors, transcription factors, genes that have an important role in development, and genes involved in cell growth. Sixteen selected stemness genes are known to be mutated or abnormally regulated in acute leukemias. It can be suggested that key hematopoietic stemness machinery genes may lead to abnormal proliferation and leukemia upon mutation or change of their expression.

Vesnarinone: a differentiation-inducing anti-cancer drug

Vesnarinone has been shown to be a unique anti-proliferating, differentiation-inducing and apoptosis inducing drug against several human malignancies, including leukemia and several solid tumors. Furthermore, vesnarinone potentiates the effect of conventional cytotoxic chemotherapy or radiation therapy. Combination of differentiation-inducing therapy by vesnarinone with conventional chemotherapy or radiation therapy might be second- or third-line therapy in patients with advanced cancer. Analysis of the molecular mechanisms of the tumor differentiation therapy by vesnarinone might provide selective and targeted molecules for novel tumor dormancy therapy.

Posttranscriptional regulation of TSC-22 (TGF-beta-stimulated clone-22) gene by TGF-beta 1

TSC-22 gene was composed of three exons and its length was approximately 5.5 kb including 2.9 kb promoter region. The transcription starting site was located at 7 and 29 bp downstream from TATA box. Promoter analysis revealed that 2146 bp of TSC-22 promoter was activated by several differentiation inducing drugs. Although originally TSC-22 was isolated as a TGF-beta-inducible gene, TSC-22 promoter was not activated by the enhanced TGF-beta signaling. We found 3 copies of the Shaw-Kamens sequence (AUUUA) in the human TSC-22 mRNA 3'-UTR and identified three proteins (40, 20, and 15 kDa) which bound to this. Only the 40 kDa protein-RNA complex was decreased by treatment with TGF-beta 1. Moreover, the TSC-22 mRNA 3'-UTR destabilized the heterologous luciferase mRNA, but the destabilization was recovered with TGF-beta 1. These observations suggest that up-regulation of TSC-22 mRNA by TGF-beta 1 is achieved by mRNA stabilization, but not by transcriptional activation.

The role of the TSC-22 (-396) A/G variant in the development of diabetic nephropathy

TSC-22 is a leucine zipper transcriptional factor and expression of the TSC-22 gene is highly induced by TGF-beta treatment. We estimated the frequency of the -396 A/G polymorphism of the TSC-22 gene with an Alu I-Restriction fragment length polymorphism (RFLP) method in 498 Japanese subjects with type 2 diabetes mellitus. We also determined the promoter activity. The diabetic patients with the AA genotype had a significantly higher incidence of the diabetic nephropathy (vs. the AG genotype, P<0.05, odds ratio: 1.95; 95% confidence intervals 1.14-3.33). There was no significant difference in the promoter activity between the fragments with -396A and -396G. These findings suggest that the TSC-22 gene (-396) A allele is associated with an increasing risk of the diabetic nephropathy.

Peroxisome proliferator-activated receptor gamma and transforming growth factor-beta pathways inhibit intestinal epithelial cell growth by regulating levels of TSC-22

Peroxisome proliferator-activated receptor gamma (PPARgamma) and transforming growth factor-beta (TGF-beta) are key regulators of epithelial cell biology. However, the molecular mechanisms by which either pathway induces growth inhibition and differentiation are incompletely understood. We have identified transforming growth factor-simulated clone-22 (TSC-22) as a target gene of both pathways in intestinal epithelial cells. TSC-22 is member of a family of leucine zipper containing transcription factors with repressor activity. Although little is known regarding its function in mammals, the Drosophila homolog of TSC-22, bunched, plays an essential role in fly development. The ability of PPARgamma to induce TSC-22 was not dependent on an intact TGF-beta1 signaling pathway and was specific for the gamma isoform. Localization studies revealed that TSC-22 mRNA is enriched in the postmitotic epithelial compartment of the normal human colon. Cells transfected with wild-type TSC-22 exhibited reduced growth rates and increased levels of p21 compared with vector-transfected cells. Furthermore, transfection with a dominant negative TSC-22 in which both repressor domains were deleted was able to reverse the p21 induction and growth inhibition caused by activation of either the PPARgamma or TGF-beta pathways. These results place TSC-22 as an important downstream component of PPARgamma and TGF-beta signaling during intestinal epithelial cell differentiation.

Downregulation of putative tumor suppressor gene TSC-22 in human brain tumors

BACKGROUND AND OBJECTIVES

Our objective was to identify differentially expressed genes involved in the pathogenesis of glioblastoma multiforme (GBM).

METHODS

Screening of arrayed human fetal brain and human postnatal brain cDNA libraries was performed by differential hybridization with glioblastoma multiforme and human normal brain cDNAs.

RESULTS

Repeated differential hybridization of more than 100 cDNA clones selected by primary screening and analysis of RNA from adult normal brain and glial tumors showed 16 nucleotide sequences differentially expressed between normal brain and brain tumors. Among others, decreased content in astrocytic tumors was determined for TSC-22 mRNA corresponding to cDNA in the ICRFp507J1041 clone from human fetal brain cDNA library. Northern blot hybridization of RNA from different human brain tumors showed very low amounts of TSC-22 mRNA in most investigated samples of GBM, anaplastic astrocytoma, and some other tumors. Complete lack of expression of TSC-22 occurred in one sample of anaplastic astrocytoma, as well as in meningioma, brain sarcoma, sarcomatous meningioma, and oligodendroglioma. The differential expression of TSC-22 gene was confirmed by semiquantitative RT-PCR in 15 samples of astrocytomas WHO grade II-IV and three samples of normal brain.

CONCLUSIONS

Significantly decreased levels of TSC-22 mRNA in human brain and salivary gland tumors and antiproliferative role of TSC-22 strongly suggest a tumor suppressor role for TSC-22. J.

Gene expression of TPA induced differentiation in HL-60 cells by DNA microarray analysis

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) is a potent inducer of differentiation in human promyelocytic leukemia cells. Recently, TPA has been successfully administered to patients with myelocytic leukemia and has produced therapeutic effects that led to temporary remission. These studies demonstrated the potential efficacy of TPA in cancer chemotherapy. We now seek to understand the biological effects and molecular mechanisms of differentiation in response to TPA treatment in leukemia cells by expression profiling using DNA microarray. Our results show distinct temporal and coordinated gene changes that are consistent with differentiation and activation of multiple biochemical pathways in HL-60 cells exposed to TPA. Alterations of gene expression in HL-60 cells include various transcription factors, cytokines and protein markers that are consistent with the induction of differentiation elicited by TPA. These temporal patterns of gene expression were abolished or greatly diminished in an HL-60 derived TPA- resistant variant cell line (HL-525), thus revealing transcriptional and consequential biochemical changes that may be required for TPA-induced differentiation. In addition, certain genes were upregulated by TPA in TPA-resistant HL-525 cells but not in TPA-sensitive HL-60 cells suggesting that these genes may play a role in the resistant phenotype. These patterns of gene expression may be important for predicting response to TPA.

Cytoplasmic TSC-22 (transforming growth factor-beta-stimulated clone-22) markedly enhances the radiation sensitivity of salivary gland cancer cells

We transfected a salivary gland cancer cell line, TYS, with three different forms of TSC-22 (transforming growth factor-beta-stimulated clone-22) gene: full-length TSC-22 (TSC-22FL) containing nuclear export signal, TSC-box and leucine zipper, truncated TSC-22 (TSC-22LZ) containing only TSC-box and leucine zipper, and truncated TSC-22 with nuclear localization signal (NLS-TSC-22LZ). High expression of TSC-22FL in the cytoplasm markedly enhanced the radiation-sensitivity of TYS cells, while, moderate expression of TSC-22FL marginally affected the radiation-sensitivity. TSC-22LZ, which was expressed in the cytoplasm and the nucleus, enhanced the radiation-sensitivity of TYS cells irrespective to its expression level. NLS-TSC-22LZ, which was expressed only in the nucleus, marginally affected the radiation-sensitivity of the cells even at high expression level. Interestingly, cytoplasmic TSC-22 translocates to nucleus concomitant with radiation-induced apoptosis. These results suggest that cytoplasmic localization of TSC-22 and translocation of TSC-22 from cytoplasm to nucleus is important for regulating the cell death signal after irradiation-induced DNA damage.

Opposing effects on TSC-22 expression by BMP and receptor tyrosine kinase signals in the developing feather tract

TSC-22 (transforming growth factor-beta-stimulated clone 22) belongs to a family of leucine zipper transcription factors that includes sequences from invertebrates and vertebrates. The single Drosophila family member, encoded by the bunched gene, serves to integrate opposing bone morphogenic protein (BMP) and epidermal growth factor (EGF) signals during oogenesis. Similarly, mammalian TSC-22 expression is regulated by several families of secreted signaling molecules in cultured cells. Here, we show that chick TSC-22 is dynamically expressed in the condensing feather bud, as well as in many tissues of the chick embryo. BMP-2/4, previously shown to inhibit bud development, repress TSC-22 expression during feather bud formation in vivo. Noggin, a BMP antagonist, promotes TSC-22 expression. EGF, TGF-alpha, and fibroblast growth factor all promote both feather bud development and TSC-22 expression; each can promote ectopic feather buds that are regularly spaced between existing feather buds. Thus, TSC-22 is a candidate to integrate small imbalances in receptor tyrosine kinase and BMP signaling during feather tract development to generate stable and reproducible morphogenetic responses.

Expression screening for Lhx3 downstream genes identifies Thg-1pit as a novel mouse gene involved in pituitary development

Thg-1pit, a novel mouse gene, was detected in a screen for genes that are differentially expressed in the developing pituitary of wild-type and Lhx3 null mutant embryos. The predicted translation product of the Thg-1pit gene contains a C-terminal TSC-box adjacent to a leucine zipper motif. These features are characteristic for the TSC-22/DIP/bun family of proteins. The onset of prominent Thg-1pit expression coincides with Lhx3 activation at early stages of pituitary development. Expression is further enhanced as cells begin to differentiate within the developing pituitary gland. No expression is observed in the pituitary rudiment of mutants that lack Lhx3 function. A possible role is thus suggested for Lhx3 activities in the regulation of Thg-1pit function during early steps of pituitary organogenesis.

Novel association of a diverse range of genes with renal cell carcinoma as identified by differential display

We have used differential-display PCR (DD-PCR) to compare renal-cell carcinoma (RCC) and normal kidney gene expression with the aim of identifying genes specifically associated with RCC. Using a modified DD-PCR approach, which was non-radioactive, quicker and simpler than the conventional method, 24 cDNA samples were clearly up- or down-regulated in RCC tissue from 4 patients. Fourteen of these showed high similarity to a number of known genes. Eight of these cDNA clones were chosen for further analysis. These were a regulator of G-protein signalling (RGS-5), Notch-3, Na,K-ATPase alpha subunit, HLA class II antigen, ETS-like protein, transforming growth factor beta-stimulated clone (TSC-22), bladder cancer-related protein (BC10) and adipophilin. Semi-quantitative RT-PCR using specific primers to each of these genes confirmed differential expression in 67% to 83% of a further 12 RCC and normal kidney paired samples from 7 of the 8 cDNA clones. Northern analysis further confirmed the up-regulation in expression of RGS-5 and Notch-3 in RCC. Further characterisation of these differentially expressed genes should lead to a better understanding of the changes that occur at the molecular level during RCC development and progression.

Nuclear translocation of TSC-22 (TGF-beta-stimulated clone-22) concomitant with apoptosis: TSC-22 as a putative transcriptional regulator

We examined the alteration of the subcellular localization of TSC-22 (TGF-beta-stimulated clone-22) after induction of apoptosis and the transcription-regulatory activity of TSC-22. In the living cells, TSC-22-green fluorescent protein (GFP) fusion protein was clearly localized to the cytoplasm, however, in the apoptotic cells, the TSC-22-GFP fusion protein was translocated from the cytoplasm to the nucleus. TSC-22 fused to GAL4-DNA binding domain (GAL4BD) did not show the transcriptional activity on the reporter genes in yeast and in HSG (salivary gland cancer cells) and Hela. However, in CHO cells, TSC-22-GAL4BD fusion protein strongly activated the reporter gene. The transcriptional activity of the leucine zipper structure of TSC-22 is greater than that of the full-length TSC-22. These findings suggest that after receiving the apoptotic stimuli, TSC-22 translocates from the cytoplasm to the nucleus and shows the transcription-regulatory activity.

Expression of TGF-beta stimulated clone-22 (TSC-22) in mouse development and TGF-beta signalling

TSC-22 is a highly conserved member of a novel family of transcription factors, that is a direct target of transforming growth factor-beta (TGF-beta) in osteoblastic cells. We have investigated the expression of TSC-22 in detail during mouse development using in situ hybridization. We detected strong expression of TSC-22 in the embryo proper first at embryonic day 8.5 (E8.5), in the primitive heart, intermediate mesoderm and the neural tube. The dynamics of the TSC-22 distribution in the neural tube was particularly striking, with ubiquitous expression rostrally and restriction to neural tissue nearer the floor plate more caudally; between E8.5 and E9.5 the zone of restricted expression extended rostrally. At later stages of development, TSC-22 was detected in the mesenchymal compartment of many tissues and organs, including the lung, trachea, kidney, stomach, intestine, tooth buds, and in precartilage condensations. Furthermore, TSC-22 was highly expressed in the floor plate itself and notochord, and the endothelium lining the blood vessels, in particular the major arteries. Many of these sites have been proposed previously as possible TGF-beta target tissues; the results imply that TSC-22 may also be a direct TGF-beta target gene during mouse embryogenesis. Experiments on TSC-22 expression in embryoid bodies of embryonic stem (ES) cells expressing dominant negative TGF-beta binding receptors initially supported this hypothesis. However, examination of somatic chimeras derived from these same mutant ES cells at nominal E9.5 showed that TSC-22 expression in the heart and neural tube was still detectable despite obvious phenotypic abnormalities. We therefore propose that although TSC-22 may be a direct target of TGF-beta in late development, other factors are likely to be major regulators of expression at earlier stages.

Over-expression of TSC-22 (TGF-beta stimulated clone-22) markedly enhances 5-fluorouracil-induced apoptosis in a human salivary gland cancer cell line

We have recently isolated TSC-22 (transforming growth factor-beta-stimulated clone-22) cDNA as an anticancer, drug-inducible (with vesnarinone) gene in a human salivary gland cancer cell line, TYS. We have also reported that TSC-22 negatively regulates the growth of TYS cells and that down-regulation of TSC-22 in TYS cells plays a major role in salivary gland tumorigenesis (Nakashiro et al, 1998). In this study, we transfected TYS cells with an expression vector encoding the TSC-22-GFP (green fluorescent protein) fusion protein, and we established TSC-22-GFP-expressing TYS cell clones. Next, we examined (a) the subcellular localization of the fusion protein, (b) the sensitivity of the transfectants to several anticancer drugs (5-fluorouracil, cis-diaminedichloroplatinum, peplomycin), and (c) induction of apoptotic cell death in the transfectants by 5-fluorouracil treatment. The TSC-22-GFP fusion protein was clearly localized to the cytoplasm, but not to the nucleus. Over-expression of the TSC-22-GFP fusion protein did not affect cell growth, but significantly increased the sensitivity of the cells to the anticancer drugs (p < 0.01; one-way ANOVA). Furthermore, over-expression of the TSC-22-GFP fusion protein markedly enhanced 5-fluorouracil-induced apoptosis. These findings suggest that over-expression of TSC-22-GFP protein in TYS cells enhances the chemosensitivity of the cells via induction of apoptosis.

Transforming growth factor-beta-stimulated clone-22 is a member of a family of leucine zipper proteins that can homo- and heterodimerize and has transcriptional repressor activity

TGF-beta-stimulated clone-22 (TSC-22) encodes a leucine zipper-containing protein that is highly conserved during evolution. Two homologues are known that share a similar leucine zipper domain and another conserved domain (designated the TSC box). Only limited data are available on the function of TSC-22 and its homologues. TSC-22 is transcriptionally up-regulated by many different stimuli, including anti-cancer drugs and growth inhibitors, and recent data suggest that TSC-22 may play a suppressive role in tumorigenesis. In this paper we show that TSC-22 forms homodimers via its conserved leucine zipper domain. Using a yeast two-hybrid screen, we identified a TSC-22 homologue (THG-1) as heterodimeric partner. Furthermore, we report the presence of two more mammalian family members with highly conserved leucine zippers and TSC boxes. Interestingly, both TSC-22 and THG-1 have transcriptional repressor activity when fused to a heterologous DNA-binding domain. The repressor activity of TSC-22 appears sensitive for promoter architecture, but not for the histone deacetylase inhibitor trichostatin A. Mutational analysis showed that this repressor activity resides in the non-conserved regions of the protein and is enhanced by the conserved dimerization domain. Our results suggest that TSC-22 belongs to a family of leucine zipper-containing transcription factors that can homodimerize and heterodimerize with other family members and that at least two TSC-22 family members may be repressors of transcription.

Dynamic expression of TSC-22 at sites of epithelial-mesenchymal interactions during mouse development

The leucine zipper transcription factor TSC-22 (TGF-beta1 Stimulated Clone-22) was first isolated from a mouse osteoblast cell line as an immediate-early target gene of TGF-beta1. However, work with other cell lines, as well as with a Drosophila homolog, bunched, suggests that it is an effector gene of various growth factors and potentially involved in the integration of multiple extracellular signals. Throughout mouse embryogenesis TSC-22 is expressed in a dynamic pattern. Although early TSC-22 expression is ubiquitous in 6.5 day embryos, as development proceeds TSC-22 expression is upregulated at sites of epithelial-mesenchymal interactions such as the limb bud, tooth primordiurn, hair follicle, kidney, lung, and pancreas. TSC-22 is also expressed in many neural crest-derived tissues including the mesenchyme of the branchial arches, the cranial, dorsal root, and sympathetic ganglia, as well as the facial cartilage and bone. Other areas of expression are the otic and optic vesicles, the heart, and cartilage and bone forming regions throughout the embryo.

Non-stoichiometric reduced complexity probes for cDNA arrays

A method is presented in which the reduced complexity and non-stoichiometric amplification intrinsic to RNA arbitrarily primed PCR fingerprinting (RAP-PCR) is used to advantage to generate probes for differential screening of cDNA arrays. RAP-PCR fingerprints were converted to probes for human cDNA clones arrayed as Escherichia coli colonies on nylon membranes. Each array contained 18 432 cDNA clones from the IMAGE consortium. Hybridization to approximately 1000 cDNA clones was detected using each RAP-PCR probe. Different RAP-PCR fingerprints gave hybridization patterns having very little overlap (<3%) with each other or with hybridization patterns from total cDNA probes. Consequently, repeated application of RAP-PCR probes allows a greater fraction of the message population to be screened on this type of array than can be achieved with a radiolabeled total cDNA probe. This method was applied to RNA from HaCaT keratinocytes treated with epidermal growth factor. Two RAP-PCR probes detected hybridization to 2000 clones, from which 22 candidate differentially expressed genes were observed. Differential expression was tested for 15 of these clones using RT-PCR and 13 were confirmed. The use of this cDNA array to analyze RAP-PCR fingerprints allowed for an increase in detection of 10-20-fold over the conventional denaturing polyacrylamide gel approach to RAP-PCR or differential display. Throughput is vastly improved by the reduction in cloning and sequencing afforded by the use of arrays. Also, repeated cloning and sequencing of the same gene or of genes already known to be regulated in the system of interest is minimized. The procedure we describe uses inexpensive arrays of plasmid clones spotted as E.coli colonies to detect differential expression, but these reduced complexity probes should also prove useful on arrays of PCR-amplified fragments and on oligonucleotide chips. Genesobserved in this manuscript: H11520, U35048, R48633, H28735, M13918, H12999, H05639, X79781, M31627, H23972, AB000712, R75916, U66894, AF067817.

Induction of TSC-22 by treatment with a new anti-cancer drug, vesnarinone, in a human salivary gland cancer cell

We undertook the present study to clarify the molecular mechanism of the effect of a new anti-cancer drug, vesnarinone, on a human salivary gland cancer cell line, TYS. We isolated TSC-22cDNA as avesnarinone-inducible gene from a cDNA library constructed from vesnarinone-treated TYS cells. TSC-22 was originally reported as a transforming growth factor (TGF)-beta-inducible gene. The expression of TSC-22 was up-regulated within a few hours after treatment with vesnarinone and was continued for 3 days. The level of TSC-22 mRNA in TYS cells was continuously increased until the cells reached confluency. Furthermore, the induction of TSC-22 by vesnarinone was inhibited by treatment with cycloheximide. When we treated the cells with an antisense oligonucleotide against TSC-22 mRNA under quiescent conditions, the antisense oligonucleotide stimulated the growth of TYS cells; however, under growing conditions the antisense oligonucleotide did not affect cell growth. Furthermore, the antisense oligonucleotide suppressed the antiproliferative effect of vesnarinone. These results suggest that TSC-22 may be a negative growth regulator and may play an important role in the antiproliferative effect of vesnarinone.

The Drosophila bunched gene is a homologue of the growth factor stimulated mammalian TSC-22 sequence and is required during oogenesis

A Drosophila melanogaster sequence homologous to the mammalian growth factor-stimulated TSC-22 gene was isolated in an enhancer trap screen for genes expressed in anterodorsal follicle cells during oogenesis. This sequence includes a 225 aa residue open reading frame that encompasses a leucine zipper motif immediately preceded by a highly conserved region (TSC box), similarly located but distinct from the basic domain of bZIP proteins. The gene encoding this sequence, bunched (bun), has been independently isolated and characterized with respect to its role in peripheral nervous system development and eye development (Treisman, J.E., Lai, Z.-C. and Rubin, G.M. (1995) Shortsighted acts in the decapentaplegic pathway in the Drosophila eye development and has homology to a mouse TGF-beta-responsive gene. Development 121, 2835-2845). In agreement with the expression of the enhancer detector insertion, in situ hybridization reveals that bun transcripts localize to the anterior dorsal follicle cells at stages 10-12 of oogenesis. Changes in bun enhancer trap expression in genetic backgrounds that disrupt the grk/Egfr signaling pathway suggest that bun is regulated by growth factor patterning of dorsal anterior follicle cell fates. Clonal analysis shows that bun is required for the proper elaboration of dorsal cell fates leading to the formation of the dorsal appendages.

Novel progesterone target genes identified by an improved differential display technique suggest that progestin-induced growth inhibition of breast cancer cells coincides with enhancement of differentiation

Progesterone is an important regulator of normal and malignant breast epithelial cells. In addition to stimulating development of normal mammary epithelium, it can be used to treat hormone-dependent breast tumors. However, the mechanism of growth inhibition by progestins is poorly understood, and only a limited number of progesterone target genes are known so far. We therefore decided to clone such target genes by means of differential display polymerase chain reaction. In this paper, we describe an improved differential display strategy that eliminates false positives, along with the identification of nine positive (TSC-22, CD-9, Na+/K+-ATPase alpha1, desmoplakin, CD-59, FKBP51, and three unknown genes) and one negative progesterone target genes (annexin-VI) from the mammary carcinoma cell line T47D, which is growth-inhibited by progestins. None of these genes have been reported before to be progesterone targets. Regulation of desmoplakin, CD-9, CD-59, Na+/K+-ATPase alpha1, and annexin-VI by the progestin suggests that progesterone induces T47D cells to differentiate. Three of these genes were repressed by estradiol and up-regulated by the progestin. Estradiol treatment of T47D cells also leads to formation of lamellipodia and delocalization of two cell adhesion proteins, E-cadherin and alpha-catenin. All these effects were reversed by the progestin. These data suggest that estradiol dedifferentiates T47D cells, while progestins have the opposite effect. This may be linked to the capacity of progestins to inhibit tumor growth.