Post-transcriptional regulation of the human transforming growth factor-beta 1 gene

Protein synthesis control in cancer: selectivity and therapeutic targeting

Translational control of mRNAs is a point of convergence for many oncogenic signals through which cancer cells tune protein expression in tumorigenesis. Cancer cells rely on translational control to appropriately adapt to limited resources while maintaining cell growth and survival, which creates a selective therapeutic window compared to non-transformed cells. In this review, we first discuss how cancer cells modulate the translational machinery to rapidly and selectively synthesize proteins in response to internal oncogenic demands and external factors in the tumor microenvironment. We highlight the clinical potential of compounds that target different translation factors as anti-cancer therapies. Next, we detail how RNA sequence and structural elements interface with the translational machinery and RNA-binding proteins to coordinate the translation of specific pro-survival and pro-growth programs. Finally, we provide an overview of the current and emerging technologies that can be used to illuminate the mechanisms of selective translational control in cancer cells as well as within the microenvironment.

Extensive Variation in Gene Expression is Revealed in 13 Fertility-Related Genes Using RNA-Seq, ISO-Seq, and CAGE-Seq From Brahman Cattle

Fertility is a key driver of economic profitability in cattle production. A number of studies have identified genes associated with fertility using genome wide association studies and differential gene expression analysis; however, the genes themselves are poorly characterized in cattle. Here, we selected 13 genes from the literature which have previously been shown to have strong evidence for an association with fertility in Brahman cattle (Bos taurus indicus) or closely related breeds. We examine the expression variation of the 13 genes that are associated with cattle fertility using RNA-seq, CAGE-seq, and ISO-seq data from 11 different tissue samples from an adult Brahman cow and a Brahman fetus. Tissues examined include blood, liver, lung, kidney, muscle, spleen, ovary, and uterus from the cow and liver and lung from the fetus. The analysis revealed several novel isoforms, including seven from SERPINA7. The use of three expression characterization methodologies (5′ cap selected ISO-seq, CAGE-seq, and RNA-seq) allowed the identification of isoforms that varied in their length of 5′ and 3′ untranslated regions, variation otherwise undetectable (collapsed as degraded RNA) in generic isoform identification pipelines. The combinations of different sequencing technologies allowed us to overcome the limitations of relatively low sequence depth in the ISO-seq data. The lower sequence depth of the ISO-seq data was also reflected in the lack of observed expression of some genes that were observed in the CAGE-seq and RNA-seq data from the same tissue. We identified allele specific expression that was tissue-specific in AR, IGF1, SOX9, STAT3, and TAF9B. Finally, we characterized an exon of TAF9B as partially nested within the neighboring gene phosphoglycerate kinase 1. As this study only examined two animals, even more transcriptional variation may be present in a genetically diverse population. This analysis reveals the large amount of transcriptional variation within mammalian fertility genes and illuminates the fact that the transcriptional landscape cannot be fully characterized using a single technology alone.

Quantitation of TGF-β proteins in mouse tissues shows reciprocal changes in TGF-β1 and TGF-β3 in normal vs neoplastic mammary epithelium

Transforming growth factor-βs (TGF-βs) regulate tissue homeostasis, and their expression is perturbed in many diseases. The three isoforms (TGF-β1, -β2, and -β3) have similar bioactivities in vitro but show distinct activities in vivo. Little quantitative information exists for expression of TGF-β isoform proteins in physiology or disease. We developed an optimized method to quantitate protein levels of the three isoforms, using a Luminex® xMAP®-based multianalyte assay following acid-ethanol extraction of tissues. Analysis of multiple tissues and plasma from four strains of adult mice showed that TGF-β1 is the predominant isoform with TGF-β2 being ~10-fold lower. There were no sex-specific differences in isoform expression, but some tissues showed inter-strain variation, particularly for TGF-β2. The only adult tissue expressing appreciable TGF-β3 was the mammary gland, where its levels were comparable to TGF-β1. In situ hybridization showed the luminal epithelium as the major source of all TGF-β isoforms in the normal mammary gland. TGF-β1 protein was 3-8-fold higher in three murine mammary tumor models than in normal mammary gland, while TGF-β3 protein was 2-3-fold lower in tumors than normal tissue, suggesting reciprocal regulation of these isoforms in mammary tumorigenesis.

Severe acute respiratory syndrome coronaviruses with mutations in the E protein are attenuated and promising vaccine candidates

Severe acute respiratory syndrome coronavirus (SARS-CoV) causes a respiratory disease with a mortality rate of 10%. A mouse-adapted SARS-CoV (SARS-CoV-MA15) lacking the envelope (E) protein (rSARS-CoV-MA15-ΔE) is attenuated in vivo. To identify E protein regions and host responses that contribute to rSARS-CoV-MA15-ΔE attenuation, several mutants (rSARS-CoV-MA15-E*) containing point mutations or deletions in the amino-terminal or the carboxy-terminal regions of the E protein were generated. Amino acid substitutions in the amino terminus, or deletion of regions in the internal carboxy-terminal region of E protein, led to virus attenuation. Attenuated viruses induced minimal lung injury, diminished limited neutrophil influx, and increased CD4(+) and CD8(+) T cell counts in the lungs of BALB/c mice, compared to mice infected with the wild-type virus. To analyze the host responses leading to rSARS-CoV-MA15-E* attenuation, differences in gene expression elicited by the native and mutant viruses in the lungs of infected mice were determined. Expression levels of a large number of proinflammatory cytokines associated with lung injury were reduced in the lungs of rSARS-CoV-MA15-E*-infected mice, whereas the levels of anti-inflammatory cytokines were increased, both at the mRNA and protein levels. These results suggested that the reduction in lung inflammation together with a more robust antiviral T cell response contributed to rSARS-CoV-MA15-E* attenuation. The attenuated viruses completely protected mice against challenge with the lethal parental virus, indicating that these viruses are promising vaccine candidates.

IMPORTANCE

Human coronaviruses are important zoonotic pathogens. SARS-CoV caused a worldwide epidemic infecting more than 8,000 people with a mortality of around 10%. Therefore, understanding the virulence mechanisms of this pathogen and developing efficacious vaccines are of high importance to prevent epidemics from this and other human coronaviruses. Previously, we demonstrated that a SARS-CoV lacking the E protein was attenuated in vivo. Here, we show that small deletions and modifications within the E protein led to virus attenuation, manifested by minimal lung injury, limited neutrophil influx to the lungs, reduced expression of proinflammatory cytokines, increased anti-inflammatory cytokine levels, and enhanced CD4(+) and CD8(+) T cell counts in vivo, suggesting that these phenomena contribute to virus attenuation. The attenuated mutants fully protected mice from challenge with virulent virus. These studies show that mutations in the E protein are not well tolerated and indicate that this protein is an excellent target for vaccine development.

The ThPOK transcription factor differentially affects the development and function of self-specific CD8(+) T cells and regulatory CD4(+) T cells

The zinc finger transcription factor ThPOK plays a crucial role in CD4 T-cell development and CD4/CD8 lineage decision. In ThPOK-deficient mice, developing T cells expressing MHC class II-restricted T-cell receptors are redirected into the CD8 T-cell lineage. In this study, we investigated whether the ThPOK transgene affected the development and function of two additional types of T cells, namely self-specific CD8 T cells and CD4(+) FoxP3(+) T regulatory cells. Self-specific CD8 T cells are characterized by high expression of CD44, CD122, Ly6C, 1B11 and proliferation in response to either IL-2 or IL-15. The ThPOK transgene converted these self-specific CD8 T cells into CD4 T cells. The converted CD4(+) T cells are no longer self-reactive, lose the characteristics of self-specific CD8 T cells, acquire the properties of conventional CD4 T cells and survive poorly in peripheral lymphoid organs. By contrast, the ThPOK transgene promoted the development of CD4(+) FoxP3(+) regulatory T cells resulting in an increased recovery of CD4(+) FoxP3(+) regulatory T cells that expressed higher transforming growth factor-β-dependent suppressor activity. These studies indicate that the ThPOK transcription factor differentially affects the development and function of self-specific CD8 T cells and CD4(+) FoxP3(+) regulatory T cells.

Intra-pituitary relationship of follicle stimulating hormone and luteinizing hormone during pubertal development in Atlantic bluefin tuna (Thunnus thynnus)

As part of the endeavor aiming at the domestication of Atlantic bluefin tuna (BFT; Thunnus thynnus), first sexual maturity in captivity was studied by documenting its occurrence and by characterizing the key hormones of the reproductive axis: follicle stimulating hormone (FSH) and luteinizing hormone (LH). The full length sequence encoding for the related hormone β-subunits, bftFSHβ and bftLHβ, were determined, revealing two bftFSHβ mRNA variants, differing in their 5' untranslated region. A quantitative immuno-dot-blot assay to measure pituitary FSH content in BFT was developed and validated enabling, for the first time in this species, data sets for both LH and FSH to be compared. The expression and accumulation patterns of LH in the pituitary showed a steady increase of this hormone, concomitant with fish age, reaching higher levels in adult females compared to males of the same age class. Conversely, the pituitary FSH levels were elevated only in 2Y and adult fish. The pituitary FSH to LH ratio was consistently higher (>1) in immature than in maturing or pubertal fish, resembling the situation in mammals. Nevertheless, the results suggest that a rise in the LH storage level above a minimum threshold may be an indicator of the onset of puberty in BFT females. The higher pituitary LH levels in adult females over males may further support this notion. In contrast three year-old (3Y) males were pubertal while cognate females were still immature. However, it is not yet clear whether the advanced puberty in the 3Y males was a general feature typifying wild BFT populations or was induced by the culture conditions. Future studies testing the effects of captivity and hormonal treatments on precocious maturity may allow for improved handling of this species in a controlled environment which would lead to more cost-efficient farming.

Effect of conceptus on transforming growth factor (TGF) β1 mRNA expression and protein concentration in the porcine endometrium--in vivo and in vitro studies

Transforming growth factor (TGF) β and its receptors are expressed at the conceptus-maternal interface during early pregnancy in the pig. The present studies were conducted to examine: (1) the effect of conceptus products on TGFβ1 mRNA expression and protein concentration in the porcine endometrium using in vivo and in vitro models, and (2) the effect of TGFβ1 on proliferation of porcine trophoblast cells in vitro. During in vivo experiments, gilts with one surgically detached uterine horn were slaughtered on days 11 or 14 of the estrous cycle and pregnancy. For in vitro studies, endometrial explants and luminal epithelial (LE) cells co-cultured with stromal (ST) cells were treated with conceptus-exposed medium (CEM). Moreover, porcine trophoblast cells were treated with TGFβ1, and the number of viable cells was measured. On day 11, the presence of conceptuses had no effect on TGFβ1 mRNA expression, but decreased the TGFβ1 protein concentration in the connected uterine horn compared with the detached uterine horn. In contrast to day 11, on day 14 after estrus, TGFβ1 mRNA expression and protein content in the endometrium collected from the gravid uterine horn were greater when compared with the contralateral uterine horn. The treatment of endometrial slices with CEM resulted in greater TGFβ1 mRNA expression and protein secretion. LE cells responded to CEM with an increased TGFβ1 mRNA level. Moreover, TGFβ1 stimulated the proliferation of day 14 trophoblast cells. In summary, porcine conceptuses may regulate TGFβ1 synthesis in the endometrium at the time of implantation. TGFβ1, in turn, may promote conceptus development by increasing the proliferation of trophoblast cells.

The role of RNA structure in posttranscriptional regulation of gene expression

As more information is gathered on the mechanisms of transcription and translation, it is becoming apparent that these processes are highly regulated. The formation of mRNA secondary and tertiary structures is one such regulatory process that until recently it has not been analysed in depth. Formation of these mRNA structures has the potential to enhance and inhibit alternative splicing of transcripts, and regulate rates and amount of translation. As this regulatory mechanism potentially impacts at both the transcriptional and translational level, while also potentially utilising the vast array of non-coding RNAs, it warrants further investigation. Currently, a variety of high-throughput sequencing techniques including parallel analysis of RNA structure (PARS), fragmentation sequencing (FragSeq) and selective 2-hydroxyl acylation analysed by primer extension (SHAPE) lead the way in the genome-wide identification and analysis of mRNA structure formation. These new sequencing techniques highlight the diversity and complexity of the transcriptome, and demonstrate another regulatory mechanism that could become a target for new therapeutic approaches.

Before It Gets Started: Regulating Translation at the 5' UTR

Translation regulation plays important roles in both normal physiological conditions and diseases states. This regulation requires cis-regulatory elements located mostly in 5' and 3' UTRs and trans-regulatory factors (e.g., RNA binding proteins (RBPs)) which recognize specific RNA features and interact with the translation machinery to modulate its activity. In this paper, we discuss important aspects of 5' UTR-mediated regulation by providing an overview of the characteristics and the function of the main elements present in this region, like uORF (upstream open reading frame), secondary structures, and RBPs binding motifs and different mechanisms of translation regulation and the impact they have on gene expression and human health when deregulated.

A conserved stem loop motif in the 5'untranslated region regulates transforming growth factor-β(1) translation

Transforming growth factor-β₁ (TGF-β₁) regulates cellular proliferation, differentiation, migration, and survival. The human TGF-β₁ transcript is inherently poorly translated, and translational activation has been documented in relation to several stimuli. In this paper, we have sought to identify in cis regulatory elements within the TGF-β₁ 5′Untranslated Region (5′UTR). In silico analysis predicted formation of stable secondary structure in a G/C-rich element between nucleotides +77 to +106, and demonstrated that this element is highly conserved across species. Circular dichroism spectroscopy confirmed the presence of secondary structure in this region. The proximal 5′UTR was inhibitory to translation in reporter gene experiments, and mutation of the secondary structure motif increased translational efficiency. Translational regulation of TGF-β₁ mRNA is linked to altered binding of YB-1 protein to its 5′UTR. Immunoprecipitation-RT-qPCR demonstrated a high basal association of YB-1 with TGF-β₁ mRNA. However, mutation of the secondary structure motif did not prevent interaction of YB-1 with the 5′UTR, suggesting that YB-1 binds to this region due to its G/C-rich composition, rather than a specific, sequence-dependent, binding site. These data identify a highly conserved element within the TGF-β₁ 5′UTR that forms stable secondary structure, and is responsible for the inherent low translation efficiency of this cytokine.

Regulating the availability of transforming growth factor ß1 in B104 neuroblastoma cells

Transforming growth factor (TGF) beta1 is a key player in early brain development, hence, its availability (i.e., synthesis and release) affects neuronogenesis. TGFbeta1 moves proliferating cells out of the cell cycle and promotes their subsequent migration. The present study tested the hypothesis that neural progenitors self-regulate TGFbeta1. B104 neuroblastoma cells which can grow in the absence of serum or growth factors were used in systematic studies of transcription, translation, release, and activation. These studies relied on quantitative enzyme-linked immunosorbent assays and real-time polymerase chain reactions. TGFbeta1 positively upregulated its own intracellular expression and promoted increased release of TGFbeta1 from cells. The induction of TGFbeta1 was independent of a change in transcription, but it depended on cycloheximide-inhibited translation. Signaling mediated by downstream Smad2/3 through the TGFbeta receptors and intracellular protein transport were also required for release of TGFbeta1 from B104 cells. Thus, TGFbeta1 production and release were mediated through a feed-forward mechanism and were pivotally regulated at the level of translation. These activities appear to be key for the role of TGFbeta1 in the proliferation and migration of young neurons.

Influence of transforming growth factor-beta1 gene polymorphism at codon 10 on the development of cirrhosis in chronic hepatitis B virus carriers

Transforming growth factor (TGF)-beta1 is a key cytokine producing extracellular matrix. We evaluated the effect of TGF-beta1 gene polymorphism at codon 10 on the development of cirrhosis in patients with chronic hepatitis B. One hundred seventy eight patients with chronic hepatitis (CH, n=57) or liver cirrhosis (LC, n=121), who had HBsAg and were over 50 yr old, were enrolled. The genotypes were determined by single strand conformation polymorphism. There were no significant differences in age and sex ratio between CH and LC groups. HBeAg positivity and detection rate of HBV DNA were higher in LC than in CH groups (P=0.055 and P=0.003, respectively). There were three types of TGF-beta1 gene polymorphism at codon 10: proline homozygous (P/P), proline/leucine heterozygous (P/L), and leucine homozygous (L/L) genotype. In CH group, the proportions of P/P, P/L, and L/L genotype were 32%, 51%, and 17%, respectively. In LC group, the proportions of those genotypes were 20%, 47%, and 33%, respectively. The L/L genotype was presented more frequently in LC than in CH groups (P=0.017). Multivariate logistic regression analysis confirms that detectable HBV DNA (odds ratio [OR]: 3.037, 95% confidence interval [CI]: 1.504-6.133, P=0.002) and L/L genotype (OR: 3.408, 95% CI: 1.279-9.085, P=0.014) are risk factors for cirrhosis.

Transforming growth factor-(beta)s and mammary gland involution; functional roles and implications for cancer progression

During rodent mammary gland involution there is a dramatic increase in the expression of the transforming growth factor-beta isoform, TGF-beta3. The TGF-betas are multifunctional cytokines which play important roles in wound healing and in carcinogenesis. The responses that are activated in the remodeling of the gland during involution have many similarities with the wound healing process and have been postulated to generate a mammary stroma that provides a microenvironment favoring tumor progression. In this review we will discuss the putative role of TGF-beta during involution, as well as its effects on the mammary microenvironment and possible implications for pregnancy-associated tumorigenesis.

Characterization of two alternative Interleukin(IL)-10 5'UTR mRNA sequences, induced by lipopolysaccharide (LPS) stimulation of peripheral blood mononuclear cells

IL-10 production shows a broad-spectrum of individual response, suggesting a genetic component of approximately 75%. Different polymorphisms located close to, or within the IL-10 gene has been demonstrated to influence its transcription rate whereas the post-transcriptional regulation of IL-10 production has not well elucidated. The main responsible elements at this control level are both the 5'- and 3'-untranslated regions (UTR's) of mRNAs, and as the 3'-UTR regions are mainly involved in the stability and decay rate of mRNAs, the 5'-UTR regions mediate the binding rate of the molecule with ribosomal 40S subunit as a cis-acting element. Herein are report data on the identification of two IL10 mRNA that differ by the length of respective 5'UTR regions (160 and 288 nucleotides, respectively; EMBL accession nrs: EU751618 and EU751619) produced after stimulation of human blood samples with bacterial lipopolysaccharide (LPS). The longer 5'UTR is constitutively expressed in unstimulated PBMC cells cultured at 37 degrees C for 24h, while in LPS stimulated cells an additional IL-10 mRNA molecule, containing a shorter 5'UTR, is synthesized. RNADRAW software (http://www.rnadraw.com/) analysis have indicated that the secondary structures of the shorter 5'UTR IL-10 mRNA region is more available for the binding to the 40S ribosomal subunit. In conclusion, our data seem to suggest that LPS could influence the post-transcriptional control of IL-10 production inducing an alternative mRNA immediately available in response to the inflammatory stimulation.

Interleukin (IL)-6 modulates transforming growth factor-beta expression in skin and dermal fibroblasts from IL-6-deficient mice

BACKGROUND

Interleukin (IL-6) and transforming growth factor (TGF)-beta have been shown to play a role in skin development and maintenance.

OBJECTIVES

A link between these two cytokines has yet to be identified and therefore in this study we investigated the modulation of TGF-beta1 and TGF-beta type 2 receptor (TGF-betaR2) by IL-6 in skin.

METHODS

An IL-6 knockout (IL-6KO) fibroblast-populated lattice model and intradermal injections of IL-6 into unwounded IL-6KO mice were used to investigate the direct effects of IL-6 treatment on TGF-beta and TGF-betaR2 expression and to determine the signalling mechanism. In addition, IL-6KO and C57BL/6 control mice were wounded by a 4-mm punch biopsy to monitor expression of TGF-beta1 and TGF-betaR2 within a wound over time. The expression of TGF-beta1 and TGF-betaR2 was assessed by real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay and immunohistology.

RESULTS

Recombinant IL-6 treatment of IL-6KO lattices and intradermal injections of IL-6 showed a significant induction of TGF-beta1 mRNA and protein, with TGF-beta1 expression localized in the dermis, while TGF-betaR2 expression was primarily in the epidermis in IL-6KO mice. During healing, the expression of TGF-beta1 and TGF-betaR2 mRNA was significantly greater in unwounded and 7-day-old wounds from wild-type mice; however, protein expression did not differ. Treatment with signal transduction inhibitors indicated that IL-6 modulates TGF-beta through a mitogen-activated protein kinase/extracellular signal-regulated kinase (Mapk/Erk)-dependent mechanism.

CONCLUSION

These studies indicate that IL-6 has the ability to modulate the expression of TGF-beta and TGF-betaR2 to varying degrees in the skin, which may provide a possible mechanism for defining the role of IL-6 in skin maintenance and a new association of IL-6 with TGF-beta in pathologies associated with fibrosis.

Transcriptional and translational regulation of TGF-beta production in response to apoptotic cells

Interaction between apoptotic cells and phagocytes through phosphatidylserine recognition structures results in the production of TGF-beta, which has been shown to play pivotal roles in the anti-inflammatory and anti-immunogenic responses to apoptotic cell clearance. Using 3T3-TbetaRII and RAWTbetaRII cells in which a truncated dominant-negative TGF-beta receptor II was stably transfected to avoid autofeedback induction of TGF-beta, we investigate the mechanisms by which TGF-beta was produced through PSRS engagement. We show, in the present study, that TGF-beta was regulated at both transcriptional and translational steps. P38 MAPK, ERK, and JNK were involved in TGF-beta transcription, whereas translation required activation of Rho GTPase, PI3K, Akt, and mammalian target of rapamycin with subsequent phosphorylation of translation initiation factor eukaryotic initiation factor 4E. Strikingly, these induction pathways for TGF-beta production were different from those initiated in the same cells responding to LPS or PMA.

The DEAD-box RNA helicase DDX3 associates with export messenger ribonucleoproteins as well as tip-associated protein and participates in translational control

Nuclear export of mRNA is tightly linked to transcription, nuclear mRNA processing, and subsequent maturation in the cytoplasm. Tip-associated protein (TAP) is the major nuclear mRNA export receptor, and it acts coordinately with various factors involved in mRNA expression. We screened for protein factors that associate with TAP and identified several candidates, including RNA helicase DDX3. We demonstrate that DDX3 directly interacts with TAP and that its association with TAP as well as mRNA ribonucleoprotein complexes may occur in the nucleus. Depletion of TAP resulted in nuclear accumulation of DDX3, suggesting that DDX3 is, at least in part, exported along with messenger ribonucleoproteins to the cytoplasm via the TAP-mediated pathway. Moreover, the observation that DDX3 localizes transiently in cytoplasmic stress granules under cell stress conditions suggests a role for DDX3 in translational control. Indeed, DDX3 associates with translation initiation complexes. However, DDX3 is probably not critical for general mRNA translation but may instead promote efficient translation of mRNAs containing a long or structured 5' untranslated region. Given that the DDX3 RNA helicase activity is essential for its involvement in translation, we suggest that DDX3 facilitates translation by resolving secondary structures of the 5'-untranslated region in mRNAs during ribosome scanning.

TGFbeta signalling in control of T-cell-mediated self-reactivity

In the immune system, transforming growth factor-beta (TGFbeta) affects multiple cell lineages by either promoting or opposing their differentiation, survival and proliferation. Understanding the cellular mechanisms of TGFbeta-mediated regulation is complicated due to a broad distribution of TGFbeta receptors on the surface of different immune-cell types. Recent studies using in vivo genetic approaches revealed a critical role for TGFbeta signalling in T cells in restraining fatal autoimmune lesions. Here, we review recent advances in our understanding of a role for TGFbeta signalling in the regulation of T-cell differentiation in the thymus and in the periphery, with a particular emphasis on TGFbeta-mediated control of self-reactive T cells.

Prognostic value of PAI1 in invasive breast cancer: evidence that tumor-specific factors are more important than genetic variation in regulating PAI1 expression

Plasminogen activator inhibitor-1 (PAI1) can promote cancer progression, and its protein expression in tumors is an independent indicator of poor prognosis in many forms of cancer. Here, we show that high PAI1 mRNA levels also predict for shorter overall survival in two independent breast cancer data sets, highlighting the importance of its transcriptional regulation. The -675insG (4G/5G) single-nucleotide polymorphism in the PAI1 gene promoter has been shown to influence PAI1 transcription, with the 4G allele eliciting higher reporter gene expression in vitro and higher levels of circulating PAI1 in vivo. Nevertheless, its genotypic distribution in 2,539 British women with invasive breast cancer was virtually identical to that seen in 1,832 matched controls (P = 0.72), and annual mortality rates for 4G4G, 4G5G, and 5G5G cases were 2.6%, 2.8%, and 3.1% per year, respectively (P = 0.10). Thus, there was no association with breast cancer incidence or outcome, and in a separate set of breast cancers, the 4G/5G single-nucleotide polymorphism showed no association with PAI1 mRNA expression (P = 0.85). By contrast, connective tissue growth factor (CTGF), which can regulate PAI1 expression in culture, was associated with PAI1 expression in three independent cohorts (P << 0.0001). In addition, PAI1 gene copy number differences in the tumors were correlated with PAI1 mRNA expression (P = 0.0005) and seemed to affect expression independently of CTGF. Thus, local factors, such as CTGF and genomic amplification, seem to be more important than germ line genetic variation in influencing PAI1 expression and its untoward effects in breast cancer.

Dynamics of expression of growth differentiation factor 15 in normal and PIN development in the mouse

Growth differentiation factor (GDF15) is a distant member of the transforming growth factor-beta superfamily, a diverse group of structurally related proteins that exert multiple effects on cell fate such as on cell growth and differentiation but little is known about GDF15 in these processes. Previously we observed the mature GDF15 to be associated with human prostate carcinogenesis hence prompting us to study GDF15 further. Here we report gdf15 expression both at the RNA and protein levels, in normal prostatic tissues of wild type (wt) and prostatic intraepithelial neoplasia (PIN) of transgenic (Tg) 12T-7s model mice during embryonic, postnatal, and adult prostate formation up to 15 weeks after birth. Dynamic changes in expression, at both the mRNA and protein level, correlated with cell proliferation and differentiation during distinct phases of normal mouse prostate development and alterations in the dynamics of gdf15 expression correlated with the changes in development resulting in PIN formation. Most notably mature gdf15 protein was significantly elevated during hyperplasia and PIN development. Changes in the protein levels did not always correlate well with the mRNA levels. This was more prominent during PIN than during normal prostate development suggesting that this may also be an indicator of disturbed regulation of gdf15 in PIN. We propose that gdf15 is a growth factor with dual function either promoting proliferation or growth arrest and differentiation due most likely to differences in cellular differentiation. Because of the differentiation defect in PIN its epithelium no longer responds to gdf15 by cellular growth arrest as does the normal epithelium and gdf may even stimulate proliferation. The data supports our hypothesis that GDF15 plays a role in the early stages of human prostate cancer.

Increased expression of TGF-beta1 reduces tumor growth of human U-87 Glioblastoma Cells in vivo

The role that transforming growth factor beta1 (TGF-beta1) plays in influencing growth of glioma cells is somewhat controversial. To further understand the potential growth-regulatory effects of TGF-beta1,we constructed an animal astroglial tumor model by injecting either wild-type or virally transduced human U-87 glioblastoma cells into nude rat brains. Wild type U-87 cells produced very low amounts of TGF-beta1 and were highly tumorigenic. In contrast, U-87 cells transduced to express high levels of TGF-beta1 showed reduced tumor size in vivo, in a dose-dependent manner. This reduction in tumor size was not due to either decreased vascularity or increased apoptosis. To test whether TGF-beta1 overproduction inhibited tumor growth through an autocrine mechanism, the highest TGF-beta1 producing cells were then double transduced with a vector expressing the kinase-truncated type II TGF-beta receptor. Cells expressing high levels of truncated TGF-beta receptor were less sensitive to TGF-beta1 mediated growth inhibition in vitro and produced more aggressive tumors in vivo. The data suggest that the degree of tumorigenicity of the U-87 high-grade glioblastoma cell line may be associated with correspondingly low level of production of TGF-beta1. These results also would tend to support the possibility that TGF-beta1 may be useful in treating some high-grade gliomas.

Transforming growth factor-beta regulation of immune responses

Transforming growth factor-beta (TGF-beta) is a potent regulatory cytokine with diverse effects on hemopoietic cells. The pivotal function of TGF-beta in the immune system is to maintain tolerance via the regulation of lymphocyte proliferation, differentiation, and survival. In addition, TGF-beta controls the initiation and resolution of inflammatory responses through the regulation of chemotaxis, activation, and survival of lymphocytes, natural killer cells, dendritic cells, macrophages, mast cells, and granulocytes. The regulatory activity of TGF-beta is modulated by the cell differentiation state and by the presence of inflammatory cytokines and costimulatory molecules. Collectively, TGF-beta inhibits the development of immunopathology to self or nonharmful antigens without compromising immune responses to pathogens. This review highlights the findings that have advanced our understanding of TGF-beta in the immune system and in disease.

NF-kappaB and activator protein 1 response elements and the role of histone modifications in IL-1beta-induced TGF-beta1 gene transcription

Abnormal expression of TGF-beta1 is believed to play an important role in the pathogenesis of a number of chronic inflammatory and immune lung diseases, including asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis. Gene activation in eukaryotes requires coordinated use of specific cell signals, chromatin modifications, and chromatin remodeling. We studied the roles of the ubiquitous inflammatory transcription factors, NF-kappaB and AP-1, in activation of the TGF-beta1 gene and histone acetylation at the TGF-beta1 promoter. IL-1beta-induced TGF-beta1 protein secretion and mRNA expression were prevented by actinomycin D and were attenuated by the inhibitor of kappaB kinase 2 inhibitor AS602868 and the JNK inhibitor SP600125, suggesting a degree of transcriptional regulation mediated by the NF-kappaB and AP-1 pathways. We demonstrated that IL-1beta activated the p65 subunit of NF-kappaB and the c-Jun subunit of AP-1. Using chromatin immunoprecipitation assays, we observed a sequential recruitment of p65 and c-Jun, accompanying ordered elevation of the levels of histone H4 and H3 acetylation and recruitment of RNA polymerase II at distinct regions in the native TGF-beta1 promoter. The specific NF-kappaB and AP-1 binding sites in the TGF-beta1 promoter were confirmed by an ELISA-based binding assay, and evidence for histone hyperacetylation in TGF-beta1 induction was supported by the observation that the histone deacetylase inhibitor trichostatin A enhanced basal and IL-1beta-induced TGF-beta1 mRNA expression. Our results suggest that IL-1beta-stimulated transcription of TGF-beta1 is temporally regulated by NF-kappaB and AP-1 and involves histone hyperacetylation at distinct promoter sites.

Inhibition of lymphocyte proliferation and activation: a mechanism used by equine invasive trophoblast to escape the maternal immune response

At days 36-38 of gestation, the equine invasive trophoblast cells migrate into the endometrium of the pregnant mare to form the endometrial cups. During their migration, they become surrounded by maternal CD4+ and CD8+ T lymphocytes, and stimulate a cytotoxic antibody response to the paternal major histocompatibility complex class I antigens that they express. Nevertheless, endometrial cup cells remain viable at the site of uterine invasion up to days 80-100 of gestation, suggesting the participation of immunomodulatory mechanisms to the maternal cellular immune response. To determine the effects of the invasive trophoblast cells on lymphocyte proliferation, an in vitro co-culture system was developed using isolated equine invasive trophoblast cells and peripheral blood lymphocytes. Fetal fibroblast cells from the same conceptuses were used as controls. The presence of invasive trophoblast cells or their pre-conditioned medium inhibited 50% or more of lymphocyte proliferation, while fetal fibroblasts had no effect. The invasive trophoblast cell inhibitory factor needed to be present constantly to affect lymphocyte proliferation, and it was ineffective if lymphocytes had been previously stimulated to proliferate. The lymphoproliferative inhibitory mechanism affected lymphocyte subpopulations similarly. In addition, lymphocyte expression of cytokine mRNA including IFNgamma, IL-2, IL-4, and IL-10 was affected compared to controls. The implication of these observations in vivo may explain, in part, the apparent equine maternal immune acceptance of the presence and development of endometrial cup cells.

Role for the Nuclear Factor κB Pathway in Transforming Growth Factor-β1 Production in Idiopathic Myelofibrosis: Possible Relationship with FK506 Binding Protein 51 Overexpression

The release of transforming growth factor-beta1 (TGF-beta1) in the bone marrow microenvironment is one of the main mechanisms leading to myelofibrosis in murine models and probably in the human idiopathic myelofibrosis (IMF). The regulation of TGF-beta1 synthesis is poorly known but seems regulated by nuclear factor kappaB (NF-kappaB). We previously described the overexpression of an immunophilin, FK506 binding protein 51 (FKBP51), in IMF megakaryocytes. Gel shift and gene assays show that FKBP51's overexpression in a factor-dependent hematopoietic cell line, induces a sustained NF-kappaB activation after cytokine deprivation. This activation correlates with a low level of IkappaBalpha. A spontaneous activation of NF-kappaB was also detected in proliferating megakaryocytes and in circulating CD34(+) patient cells. In normal cells, NF-kappaB activation was only detected after cytokine treatment. The expression of an NF-kappaB superrepressor in FKBP51 overexpressing cells and in derived megakaryocytes from CD34(+) of IMF patients revealed that NF-kappaB activation was not involved in the resistance to apoptosis after cytokine deprivation of these cells but in TGF-beta1 secretion. These results highlight the importance of NF-kappaB's activation in the fibrosis development of this disease. They also suggest that FKBP51's overexpression in IMF cells could play an important role in the pathogenesis of this myeloproliferative disorder.

Structural features of hematopoiesis-specific RhoH/ARHH gene: high diversity of 5'-UTR in different hematopoietic lineages suggests a complex post-transcriptional regulation

The hematopoiesis-specific RhoH gene is thought to be deregulated in B-cell non-Hodgkin's lymphoma (B-NHL), by either a chromosomal translocation or mutations, which affect its 5' regulatory region. The encoded Rho protein, always GTP-bound in vivo, was hypothesized to behave as a Rac antagonist. Extensive expression analysis allowed the detection of RhoH transcripts in all hematopoietic lineages (lymphoid, erythroid, myeloid), with a high level in lymphoid cells. To initiate investigations on the molecular mechanisms that regulate RhoH gene expression, Race-PCR and primer extension were conducted in the B-cell line Raji, which allowed (i) the establishment of RhoH complex intron/exon organization and (ii) the detection of several transcription initiation sites. In addition, a high 5' end heterogeneity of RhoH mRNAs was observed, due to alternative splicing of some 5' exons and to the use of these different transcription start sites. RT-PCR analysis led to the identification of this 5' end heterogeneity in different hematopoietic lineages. Discrepancies were particularly observed between B and T cells, due to an alternative splicing of one 5' exon (1b), which might be an important element in RhoH gene regulation. Such specific features have never been described for any Rho family member gene. They provide a molecular basis to study complex mechanisms involved in the control of RhoH expression.

Ca2+ signaling down-regulates TGF-beta1 gene expression in CD4+ T cells

In the immune system, TGF-beta1 exerts two major functions, anti-inflammatory and immuno-suppressive effects. This work aims to investigate the molecular mechanisms involved in the regulation of the TGF-beta1 gene expression in CD4(+) T cells. The TGF-beta1 gene expresses three transcripts of 2.5, 1.9, and 1.4kb. The 1.9kb mRNA which has the highest translation activity was the major transcript. The relationship between T cell receptor (TCR) stimulation and the expression of the gene was investigated. TCR stimulation with a low dose of antigen peptide enhanced the gene expression, whereas a higher dose suppressed the expression. TCR stimulation activates PKC/MAPK and Ca(2+) signaling pathways. PMA increased the gene expression, whereas ionomycin decreased the gene expression, markedly. The results indicate that Ca(2+) signaling down-regulates TGF-beta1 gene expression. The molecular regulation of TGF-beta1 gene expression is unique when comparing to other cytokine genes which are generally activated by Ca(2+) signaling.

The implications of structured 5' untranslated regions on translation and disease

Translational control is a key step in eukaryotic gene expression. The majority of translational control occurs at the level of initiation, thus implicating the 5' untranslated region as a major site of translational regulation. Many growth-related mRNAs have atypical 5' UTRs, which are often long and GC-rich. Such features promote formation of stable secondary structure, and many mRNAs encoding proteins involved in cell growth, proliferation and apoptosis have structured 5' UTRs, which in many cases harbour internal ribosome entry sites (IRESs) and upstream open-reading frames (uORFs). In this review we discuss how secondary structural elements in the 5' UTR can regulate translation and how mutations that perturb these secondary structural elements can have implications for disease and tumourigenesis.

Transforming growth factor beta1 (TGFbeta1) expression in head and neck squamous cell carcinoma patients as related to prognosis

BACKGROUND

Transforming growth factor beta1 (TGFbeta1) is a negative growth regulator in keratinocytes, and in vitro studies lead to the concept that loss of TGFbeta1 responsiveness is a critical step in epithelial carcinogenesis.

OBJECTIVE

To investigate the prognostic relevance of TGFbeta1 expression in head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

TGFbeta1 distribution was determined by immunohistochemistry in oral cavity/oropharynx (n = 79), larynx (n = 36) and hypopharynx (n = 25) tumors and in matched normal adjacent mucosa. TGFbeta-type I and II receptors were determined in 20 cases of differentiated oral cavity/hypopharynx tumors. Cases were considered positive if displaying reactivity in >10% of the cells.

RESULTS

TGFbeta1-positive expression was found in 47.2% of larynx, 36.7% of oral cavity/oropharynx and in 24% of the hypopharynx tumors. Reactivity in >60% of the cells was displayed only by 11.4% of HNSCC. All normal controls were positive. TGFbeta1-positive expression did not correlate with clinico pathological parameters. An association with differentiation was verified only in oral cavity/oropharynx tumors (P </= 0.001). TGFbeta1 was also not related to 5 years survival (Kaplan-Meier). Strong and diffuse expression of TGFbeta-RII was identified in 19/20 cases regardless of TGFbeta1 immunoreactivity. Out of 17 TGFbeta1-positive oral cavity/oropharynx tumors, only nine expressed TGFbeta-RI suggesting a disruption of the TGFbeta1 pathway. We conclude that TGFbeta1 protein immunostaining is not a useful biomarker in assessment of prognosis in HNSCC.

Evidence for differential ribonucleoprotein complex assembly in vitro on the 5'-untranslated region of the human IGF-IR transcript

The type I insulin-like growth factor receptor (IGF-IR) plays a key role in the control of cellular proliferation and survival. The human IGF-IR transcript is characterized by an unusually long 1038 nucleotide 5'-untranslated region (5'-UTR). We hypothesized that the contribution of this complex 5'-untranslated RNA sequence to the post-transcriptional regulation of IGF-IR expression would involve a dynamic interplay between RNA structure and specific RNA-binding proteins. Here we have detected and characterized a diverse series of regulatory proteins binding the IGF-IR 5'-UTR under disparate conditions. One pair of proteins ( approximately 42/38 kDa) binds readily to the intact 5'-UTR, which is predicted to adopt a highly base-paired, highly favorable (dG=-498 kcal/mol) three-domain structure. Another protein(s) (p20*) specifically induces formation of a novel RNA structure from within the initial 209 nucleotides of the nascent IGF-IR transcript, but fails to UV crosslink to this RNA sequence. A third group of proteins recognizes and binds the IGF-IR 5'-UTR under highly stringent conditions, but only after higher-ordered RNA structure has been disrupted. Our in vitro results indicate that the IGF-IR 5'-UTR may exist in at least three distinct states, and we propose that interconversion between these states might take place in vivo and differentially alter IGF-IR transcript utilization.

Posttranscriptional control of the expression and function of diacylglycerol acyltransferase-1 in mouse adipocytes

Acyl-CoA:diacylglycerol acyltransferase-1 (DGAT1) catalyzes the final step of triglyceride synthesis in mammalian cells. Data obtained from DGAT1-knockout mice have indicated that this enzyme plays an important role in energy homeostasis. We investigated the regulation of the expression and function of DGAT1 in mouse 3T3-L1 cell as a model for mammalian adipocytes. We demonstrated that the DGAT1 protein level increased by approximately 90-fold following differentiation of 3T3-L1 into mature adipocytes, a change that was accompanied by approximately 7-fold increase in DGAT1 mRNA. On the other hand, forced overexpression of DGAT1 mRNA by >20-fold via a recombinant adenovirus only resulted in approximately 2-fold increase in DGAT1 protein in mature adipocytes and little increase in preadipocytes. These results indicated that gene expression of DGAT1 in adipocytes is subjected to rigorous posttranscriptional regulation, which is modulated significantly by the differentiation status of 3T3-L1 cells. Protein stability is not a significant factor in the control of DGAT1 expression. The steady-state levels of DGAT1 were unaffected by blockage of proteolytic pathways by ALLN. However, translational control was suggested by sequence analysis of the 5'-untranslated region of human DGAT1 (hDGAT1) mRNA. We found that the level of DGAT1 activity was predominantly a function of the steady-state level of DGAT1 protein. No significant functional changes were observed when the conserved tyrosine phosphorylation site in hDGAT1 was mutated by a single base pair substitution. Despite only a approximately 2-fold increase in DGAT1 protein caused by recombinant viral transduction, a proportionate increase in cellular triglyceride synthesis resulted without affecting the triglyceride lipolysis rate, leading to >2-fold increase in intracellular triglyceride accumulation. No change in adipocyte morphology or in the expression levels of lipoprotein lipase, proxisomal proliferation-activating receptor-gamma, and aP2 was evident secondary to DGAT1 overexpression at different stages in 3T3-L1 differentiation. These data suggest that dysregulation of DGAT1 may play a role in the development of obesity, and manipulation of the steady-state level of DGAT1 protein may offer a potential means to treat or prevent obesity.

Kainate treatment alters TGF-beta3 gene expression in the rat hippocampus

In order to evaluate the role of transforming growth factor (TGF)-beta3 in the neurodegenerative process, we examined the levels of mRNA and immunocytochemical distribution for TGF-beta3 in the rat hippocampus after systemic kainic acid (KA) administration. Hippocampal TGF-beta3 mRNA level was reduced 3 h after KA injection. However, the levels of TGF-beta3 mRNA were elevated 1 day post-KA and lasted for at least 30 days. A mild TGF-beta3 immunoreactivity (TGF-beta3-IR) in the Ammon's horn and a moderate TGF-beta3-IR in the dentate granule cells were observed in the normal hippocampus. The CA1 and CA3 neurons lost their TGF-beta3-IR, while TGF-beta3-positive glia-like cells proliferated mainly throughout the CA1 sector and had an intense immunoreactivity at 7, 15 and 30 days after KA. This immunocytochemical distribution of TGF-beta3-positive non-neuronal populations was similar to that of glial fibrillary acidic protein (GFAP)-positive cells. Double labeling immunocytochemical analysis demonstrated colocalization of TGF-beta3- and GFAP-immunoreactivity in the same cells. These findings suggest a compensatory mechanism of astrocytes for the synthesis of TGF-beta3 protein in response to KA-induced neurodegeneration. In addition, exogenous TGF-beta3 (5 or 10 ng/i.c.v.) significantly attenuated KA-induced seizures and neuronal damages in a dose-related manner. Therefore, our results suggest that TGF-beta3 plays an important role in protective mechanisms against KA-induced neurodegeneration.

Independent regulation of transforming growth factor-beta1 transcription and translation by glucose and platelet-derived growth factor

Proximal tubular renal epithelial cells may contribute to the pathogenesis of renal interstitial fibrosis in diabetes by generation of cytokines such as transforming growth factor (TGF)-beta1. We have previously demonstrated that proximal tubular renal epithelial cell TGF-beta1 synthesis may be modulated by elevated glucose concentration and by cytokines such as platelet-derived growth factor (PDGF). The aim of the current study was to characterize the mechanism by which glucose and PDGF synergistically stimulate the generation of TGF-beta1. Addition of either 25 mmol/L of D-glucose or low-dose PDGF increased TGF-beta1 mRNA expression without stimulation of TGF-beta1 protein synthesis. In contrast sequential stimulation with 25 mmol/L of D-glucose for 48 hours followed by low-dose (25 ng/ml) PDGF led to a significant increase in TGF-beta1 synthesis. Elevated glucose concentration stimulated de novo gene transcription as assessed by stimulation of a TGF-beta1 promoter-luciferase construct. This led to induction of a poorly translated TGF-beta1 transcript determined by polysome analysis. PDGF at low dose did not influence TGF-beta1 transcription, but led to alteration in TGF-beta1 mRNA stability and translation. Without a previous glucose-induced increase in the amount of TGF-beta1 transcript, PDGF did not stimulate significant TGF-beta1 protein synthesis. At a high dose (100 ng/ml) PDGF stimulated TGF-beta1 synthesis independent of glucose concentration. This was associated with increased TGF-beta1 gene transcription and alteration in TGF-beta1 mRNA translational efficiency. In conclusion the data suggests that in diabetic nephropathy, the role of glucose is to lower the threshold at which a stimulus such as PDGF stimulates TGF-beta1 protein synthesis. The data also suggest that independent regulation of TGF-beta1 transcription and translation by glucose and PDGF account for their synergistic effect on TGF-beta1 protein synthesis. We hypothesize that the role of glucose in diabetic nephropathy is to prime the kidney for an injurious response to other stimuli.

Identification and characterization of a novel human cathepsin L splice variant

Human cathepsin L (hCATL) has been implicated in a variety of physiological and pathological processes. It was hitherto known to be encoded by four mRNA species, namely hCATL A, AI, AII and hCATL B, differing in their 5' untranslated regions (UTRs). Of these, hCATL A, AI and AII are produced by the alternative splicing of the same primary transcript. HCATL AI and hCATL AII, lack 27 and 90 bases, respectively, from the 3' end of exon 1 of hCATL A. The present study describes the identification of a new splice variant hCATL AIII, which similarly lacks 145 bases from the 3' end of exon 1 of hCATL A. It is produced by the splicing out of 136-280 bases of the first exon in addition to intron 1 of hCATL A, which together serve as an intron for hCATL AIII. HCATL AIII was observed to be the most abundant splice variant in five different human cell lines. In vitro transcription coupled translation studies revealed that hCATL AIII is translated with 4.4-, 3.9- and 1.6-fold higher efficiency as compared to hCATL A, AI and AII, respectively. These results were further confirmed by measuring the enzymatic activities of the in vitro translated products. Cloning of hCATL AIII UTR upstream to luciferase reporter gene resulted in a 3.75-fold higher expression of the reporter gene as compared to the luciferase construct containing UTR of hCATL A. Thus, we have identified a novel human cathepsin L splice variant, hCATL AIII, which is most abundant in human cell lines and is translated with highest efficiency. Our results demonstrate either the presence of a positive or absence of a negative cis-acting regulatory element(s) in the UTR of hCATL AIII that is sufficient to confer translational advantage to a heterologous mRNA. The predominance of this most efficiently translated splice variant in malignant cells suggests that it plays a key role in the over-expression of human cathepsin L in cancer.

Effects of transforming growth factor-beta1 and tumour necrosis factor-alpha on cultured fibroblasts from skin fibroma as modulated by toremifene

To determine how toremifene, an anti-oestrogen triphenylethylene derivate, reduces tumour mass, we investigated its modulation of TGF-beta1 and TNF-alpha in fibroma fibroblasts. Normal and fibroma fibroblasts, isolated from patients affected by Gardner's syndrome without or with fibroma manifestation, were cultured in vitro. Secretion of GAG, collagen and TGF-beta1 was increased in fibroma fibroblasts compared to healthy cells. The increase in TGF-beta1 secretion into the medium was associated with a parallel increase in TGF-beta1 gene expression and receptor number. Receptor cross-linking studies using radiolabelled TGF-beta1 revealed more receptors, particularly types I and II, in fibroma fibroblasts than in normal cells. Normal and fibroma fibroblasts did not synthesise TNF-alpha, but they had TNF-alpha membrane receptors, as shown by TNF-alpha assay. TNF-alpha secreted by human monocytes, which may be present in the peritumoral area, increased cell proliferation and GAG accumulation and was, in turn, enhanced by TGF-beta1 treatment. Both growth factors increased angiogenesis, as shown by the CAM assay. Toremifene reduced TGF-beta1 secretion by fibroma fibroblasts and TNF-alpha secretion by monocytes, thus downregulating cell proliferation, ECM macromolecule accumulation and angiogenic progression. We hypothesise that increased TGF-beta1 gene expression and TGF-beta1 secretion in fibroma fibroblasts as well as the subsequent rise in TNF-alpha production by monocytes may facilitate fibroma growth and that toremifene inhibits autocrine and paracrine growth factor production.

Role of TGF-beta1 in renal parenchymal scarring following childhood urinary tract infection

BACKGROUND

Significant variability exists in the outcome of renal parenchymal inflammation following urinary tract infection (UTI) in childhood as some children experience renal parenchymal scarring (RPS) while others do not scar. Since TGF-beta1 is pro-fibrotic, we examined the role of this cytokine in RPS following UTI.

METHODS

Five polymorphisms of the TGF-beta1 gene were investigated as well as the relationship between these polymorphisms and TGF-beta1 production by peripheral blood mononuclear cells (PBMC) in vitro. DNA was isolated from 91 children shown to have developed RPS, 43 children with no evidence of scarring (NS) following UTI, and 171 healthy controls. Genotyping was performed by restriction fragment length polymorphism (RFLP). PBMC were isolated from a subgroup of 24 patients from the total population. Cells were stimulated with LPS + PMA + PHA and then TGF-beta1 production was determined by ELISA.

RESULTS

Comparing the NS with the RPS group, there was an increase in the -800 GA genotypes (18.6 vs. 7.4%, P=0.05; chi2) and the Leu10-->Pro CT (62.8 vs. 41.5%, P=0.021), and a decrease in the -509 TT genotype (0.0 vs. 8.5%, P=0.049). PBMC TGF-beta1 production was higher in those patients with the -800 GG compared to those with a GA genotype stimulation index [stimulated/unstimulated TGF-beta1 levels were 1.54 interquartile range (IQR) 1.42 to 1.75 vs. 1.19, IQR 0.94 to 1.51, P=0.031].

CONCLUSIONS

There is an association between the TGF-beta1 -800 GA, -509 TT and Leu10-->Pro CT genotypes and the presence or absence of RPS. The low TGF-beta1 producer status of the -800 GA genotype may protect against the development of a pro-fibrotic pathology.

Translational regulation of renal proximal tubular epithelial cell transforming growth factor-beta1 generation by insulin

We have previously demonstrated that the proximal tubular cell may contribute to the pathogenesis of renal interstitial fibrosis in diabetes. Transforming growth factor (TGF)-beta1 is one of a group of pro-fibrotic cytokines and growth factors, which have been associated with the development of interstitial fibrosis. The aim of the current study was to examine the effect of insulin on the generation of TGF-beta1 by proximal tubular cells. HK-2 cells were grown to confluence in the absence of insulin, and serum deprived for 48 hours before all experimental manipulations. Addition of insulin (5 microg/ml) to the culture medium led to a time-dependent increase in TGF-beta1 concentration in the cell culture supernatant, and increased incorporation of radiolabeled amino acids into TGF-beta1 suggestive of de novo TGF-beta1 protein synthesis. Addition of insulin did not alter TGF-beta1 mRNA expression as assessed by reverse transcriptase-polymerase chain reaction or Northern analysis. Insulin-induced increase in TGF-beta1 concentration was not abrogated by actinomycin D, however, stimulation by insulin, in the presence of cycloheximide led to a dose-dependent decrease in TGF-beta1 production. Addition of insulin had no effect on TGF-beta1 mRNA stability as assessed by actinomycin D chase, but led to increased binding of a cytoplasmic protein to a putative stem loop structure in the 5'-UTR of TGF-beta1 mRNA, previously implicated in the posttranscriptional control of TGF-beta1 synthesis. To address the functional significance of insulin-induced alteration in TGF-beta1 synthesis, we examined its effect on matrix turnover. Insulin stimulated type IV collagen gene expression and an increase in the concentrations of the type IV collagen laid down in the extracellular matrix. This increase in type IV collagen was abrogated when cells were stimulated by insulin in the presence of an anti-TGF-beta1-blocking antibody. In conclusion the data demonstrate that insulin may directly alter the production of TGF-beta1 by renal proximal tubular cells by a posttranscriptional mechanism, and that this may have implications for the increase in extracellular matrix that accompanies diabetic nephropathy.

TGF-beta isoform and receptor expression in giant cell tumor and giant cell lesions of bone

The authors examined the distribution of tumor growth factor-beta (TGF-beta) isoforms and receptors in 35 giant cell tumor (GCT) of bone in comparison with a group of benign giant cell-containing lesions of bone, including 5 aneurysmal bone cysts, 2 cases of brown tumor of hyperparathyroidism, 3 nonossifying fibromas, and 7 cases of giant cell reparative granuloma. The results of immunohistochemical analysis of GCT showed a complete absence of TGF-beta1 expression in both mononuclear tumor cells and giant cells. Only reactive bone present within the tumor showed an intense immunoreactivity. Transforming growth factor-beta2 and TGF-beta3 were detected in the majority of cases (97.1% and 82.8%, respectively), whereas TGF-beta receptor type I (TGF-beta RI) and type II (TGF-beta RII) were diffusely expressed in all cases. Reverse transcription-polymerase chain reaction (RT-PCR) analysis performed on 10 GCTs with specific oligonucleotide primers demonstrated the presence of mRNA transcripts for TGF-beta1, 2, 3, and for TGF-beta RI and RII. Quantitative measurements of TGF-beta1 in conditioned media from primary cultures of GCT showed undetectable or very low amounts of the cytokine (0-23 pg/mL). The results of immunohistochemical analysis showed that all giant cell-containing lesions of bone were at least focally positive for the 3 isoform of TGF-beta, with positivity present both in osteoclast-like giant cells and mononuclear cells, and diffusely positive for TGF-beta RI and RII. Reverse transcription-polymerase chain reaction analysis conducted on samples from 3 nonossifying fibromas and 1 giant cell reparative granuloma confirmed the expression of the corresponding mRNA. In conclusion, according to the current data, GCT of bone can be distinguished from other giant cell-containing lesions of bone on the basis of the absence of TGF-beta1 expression at the protein level, which appears to be the result of posttranslational regulation processes.

Translational pathophysiology: a novel molecular mechanism of human disease

In higher eukaryotes, the expression of about 1 gene in 10 is strongly regulated at the level of messenger RNA (mRNA) translation into protein. Negative regulatory effects are often mediated by the 5′-untranslated region (5′-UTR) and rely on the fact that the 40S ribosomal subunit first binds to the cap structure at the 5′-end of mRNA and then scans for the first AUG codon. Self-complementary sequences can form stable stem-loop structures that interfere with the assembly of the preinitiation complex and/or ribosomal scanning. These stem loops can be further stabilized by the interaction with RNA-binding proteins, as in the case of ferritin. The presence of AUG codons located upstream of the physiological start site can inhibit translation by causing premature initiation and thereby preventing the ribosome from reaching the physiological start codon, as in the case of thrombopoietin (TPO). Recently, mutations that cause disease through increased or decreased efficiency of mRNA translation have been discovered, defining translational pathophysiology as a novel mechanism of human disease. Hereditary hyperferritinemia/cataract syndrome arises from various point mutations or deletions within a protein-binding sequence in the 5′-UTR of the L-ferritin mRNA. Each unique mutation confers a characteristic degree of hyperferritinemia and severity of cataract in affected individuals. Hereditary thrombocythemia (sometimes called familial essential thrombocythemia or familial thrombocytosis) can be caused by mutations in upstream AUG codons in the 5′-UTR of the TPO mRNA that normally function as translational repressors. Their inactivation leads to excessive production of TPO and elevated platelet counts. Finally, predisposition to melanoma may originate from mutations that create translational repressors in the 5′-UTR of the cyclin-dependent kinase inhibitor–2A gene.

Translational pathophysiology: a novel molecular mechanism of human disease

In higher eukaryotes, the expression of about 1 gene in 10 is strongly regulated at the level of messenger RNA (mRNA) translation into protein. Negative regulatory effects are often mediated by the 5′-untranslated region (5′-UTR) and rely on the fact that the 40S ribosomal subunit first binds to the cap structure at the 5′-end of mRNA and then scans for the first AUG codon. Self-complementary sequences can form stable stem-loop structures that interfere with the assembly of the preinitiation complex and/or ribosomal scanning. These stem loops can be further stabilized by the interaction with RNA-binding proteins, as in the case of ferritin. The presence of AUG codons located upstream of the physiological start site can inhibit translation by causing premature initiation and thereby preventing the ribosome from reaching the physiological start codon, as in the case of thrombopoietin (TPO). Recently, mutations that cause disease through increased or decreased efficiency of mRNA translation have been discovered, defining translational pathophysiology as a novel mechanism of human disease. Hereditary hyperferritinemia/cataract syndrome arises from various point mutations or deletions within a protein-binding sequence in the 5′-UTR of the L-ferritin mRNA. Each unique mutation confers a characteristic degree of hyperferritinemia and severity of cataract in affected individuals. Hereditary thrombocythemia (sometimes called familial essential thrombocythemia or familial thrombocytosis) can be caused by mutations in upstream AUG codons in the 5′-UTR of the TPO mRNA that normally function as translational repressors. Their inactivation leads to excessive production of TPO and elevated platelet counts. Finally, predisposition to melanoma may originate from mutations that create translational repressors in the 5′-UTR of the cyclin-dependent kinase inhibitor–2A gene.

Host genetic factors influence disease progression in chronic hepatitis C

Progressive hepatic fibrosis and cirrhosis develops in 20% to 30% of patients with chronic hepatitis C virus (HCV). We propose that host genetic factors influencing fibrogenesis may account for some of the variability in progression of this disease. In progressive fibrosis of other organs, particularly heart and kidney, production of the profibrogenic cytokine, transforming growth factor beta1 (TGF-beta1), may be enhanced by angiotensin II, the principal effector molecule of the renin-angiotensin system. The inheritance of polymorphisms in TGF-beta1, interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-alpha), and genes of the renin-angiotensin system was examined in 128 patients with chronic HCV. The influence of genotypes on the stage of hepatic fibrosis was tested after adjustment for potential confounders (age, gender, alcohol consumption, portal inflammation, and steatosis), which may have independent effects on histological severity. The stage of fibrosis was 0 in 30 (23.4%), 1 in 44 (34.4%), 2 in 27 (21.1%), and 3 or 4 in 27 (21.1%). A statistically significant relationship was seen between inheritance of high TGF-beta1- and angiotensinogen (AT)-producing genotypes and the development of progressive hepatic fibrosis. This association persisted after correcting for potential confounders. Patients who inherited neither of the profibrogenic genotypes had no or only minimal fibrosis. Knowledge of these polymorphisms may have prognostic significance in patients with chronic HCV and may direct more aggressive therapy towards those patients with an increased risk of disease progression. The documentation of a significant relationship between AT genotype and fibrosis raises the novel suggestion that angiotensin II may be another mediator of extracellular matrix production in the liver.

Transforming growth factor-beta and breast cancer: Mammary gland development

Transforming growth factor (TGF)-beta1 is a pluripotent cytokine that profoundly inhibits epithelial proliferation, induces apoptosis, and influences morphogenesis by mediating extracellular matrix deposition and remodeling. The physiologic roles of the action of TGF-beta in mammary gland, indeed in most tissues, are poorly understood. In order to understand the actions of TGF-beta, we need to take into account the complexity of its effects on different cell types and the influence of context on cellular responses. This task is further compounded by multiple mechanisms for regulating TGF-beta transcription, translation, and activity. One of the most significant factors that obscures the action of TGF-beta is that it is secreted as a stable latent complex, which consists of the 24-kDa cytokine and the 80-kDa dimer of its prepro region, called latency-associated peptide. Latency imposes a critical restraint on TGF-beta activity that is often overlooked. The extracellular process known as activation, in which TGF-beta is released from the latent complex, is emphasized in the present discussion of the role of TGF-beta in mammary gland development. Definition of the spatial and temporal patterns of latent TGF-beta activation in situ is essential for understanding the specific roles that TGF-beta plays during mammary gland development, proliferation, and morphogenesis.