Complete mitogenome of endemic plum-headed parakeet Psittacula cyanocephala - characterization and phylogenetic analysis

Psittacula cyanocephala is an endemic parakeet from the Indian sub-continent that is widespread in the illegal bird trade. Previous studies on Psittacula parakeets have highlighted taxonomic ambiguities, warranting studies to resolve the issues. Since the mitochondrial genome provides useful information concerning the species evolution and phylogenetics, we sequenced the complete mitogenome of P. cyanocephala using NGS, validated 38.86% of the mitogenome using Sanger Sequencing and compared it with other available whole mitogenomes of Psittacula. The complete mitogenome of the species was 16814 bp in length with 54.08% AT composition. P. cyanocephala mitogenome comprises of 13 protein-coding genes, 2 rRNAs and 22 tRNAs. P. cyanocephala mitogenome organization was consistent with other Psittacula mitogenomes. Comparative codon usage analysis indicated the role of natural selection on Psittacula mitogenomes. Strong purifying selection pressure was observed maximum on nad1 and nad4l genes. The mitochondrial control region of all Psittacula species displayed the ancestral avian CR gene order. Phylogenetic analyses revealed the Psittacula genus as paraphyletic nature, containing at least 4 groups of species within the same genus, suggesting its taxonomic reconsideration. Our results provide useful information for developing forensic tests to control the illegal trade of the species and scientific basis for phylogenetic revision of the genus Psittacula.

Characterization and Comparative Analyses of Mitochondrial Genomes in Single-Celled Eukaryotes to Shed Light on the Diversity and Evolution of Linear Molecular Architecture

Determination and comparisons of complete mitochondrial genomes (mitogenomes) are important to understand the origin and evolution of mitochondria. Mitogenomes of unicellular protists are particularly informative in this regard because they are gene-rich and display high structural diversity. Ciliates are a highly diverse assemblage of protists and their mitogenomes (linear structure with high A+T content in general) were amongst the first from protists to be characterized and have provided important insights into mitogenome evolution. Here, we report novel mitogenome sequences from three representatives (Strombidium sp., Strombidium cf. sulcatum, and Halteria grandinella) in two dominant ciliate lineages. Comparative and phylogenetic analyses of newly sequenced and previously published ciliate mitogenomes were performed and revealed a number of important insights. We found that the mitogenomes of these three species are linear molecules capped with telomeric repeats that differ greatly among known species. The genomes studied here are highly syntenic, but larger in size and more gene-rich than those of other groups. They also all share an AT-rich tandem repeat region which may serve as the replication origin and modulate initiation of bidirectional transcription. More generally we identified a split version of ccmf, a cytochrome c maturation-related gene that might be a derived character uniting taxa in the subclasses Hypotrichia and Euplotia. Finally, our mitogenome comparisons and phylogenetic analyses support to reclassify Halteria grandinella from the subclass Oligotrichia to the subclass Hypotrichia. These results add to the growing literature on the unique features of ciliate mitogenomes, shedding light on the diversity and evolution of their linear molecular architecture.

Of mitogens and morphogens: modelling Sonic Hedgehog mechanisms in vertebrate development

Sonic Hedgehog (Shh) Is a critical protein in vertebrate development, orchestrating patterning and growth in many developing systems. First described as a classic morphogen that patterns tissues through a spatial concentration gradient, subsequent studies have revealed a more complex mechanism, in which Shh can also regulate proliferation and differentiation. While the mechanism of action of Shh as a morphogen is well understood, it remains less clear how Shh might integrate patterning, proliferation and differentiation in a given tissue, to ultimately direct its morphogenesis. In tandem with experimental studies, mathematical modelling can help gain mechanistic insights into these processes and bridge the gap between Shh-regulated patterning and growth, by integrating these processes into a common theoretical framework. Here, we briefly review the roles of Shh in vertebrate development, focusing on its functions as a morphogen, mitogen and regulator of differentiation. We then discuss the contributions that modelling has made to our understanding of the action of Shh and highlight current challenges in using mathematical models in a quantitative and predictive way. This article is part of a discussion meeting issue 'Contemporary morphogenesis'.

Identification of two new core chromosome-encoded superantigens in Streptococcus pyogenes; speQ and speR

Superantigens are ubiquitous within the Streptococcus pyogenes genome, which suggests that superantigen-mediated T-cell activation provides a significant selective advantage. S. pyogenes can carry a variable complement of the 11 known superantigens. We have identified two novel S. pyogenes superantigens, denoted speQ and speR, adjacent to each other in the core-chromosome of isolates belonging to eleven different emm-types. Although distinct from other superantigens, speQ and speR were most closely related to speK and speJ, respectively. Recombinant SPEQ and SPER were mitogenic towards human peripheral blood mononuclear cells at ng/ml concentrations, and SPER was found to be more mitogenic than SPEQ.

Nutrient sensing, growth and senescence

Cell growth is dictated by a wide range of mitogenic signals, the amplitude and relative contribution of which vary throughout development, differentiation and in a tissue-specific manner. The ability to sense and appropriately respond to changes in mitogens is fundamental to control cell growth, and reduced responsiveness of nutrient sensing pathways is widely associated with human disease and ageing. Cellular senescence is an important tumour suppressor mechanism that is characterised by an irreversible exit from the cell cycle in response to replicative exhaustion or excessive DNA damage. Despite the fact that senescent cells can no longer divide, they remain metabolically active and display a range of pro-growth phenotypes that are supported in part by the mTORC1-autophagy signalling axis. As our understanding of the basic mechanisms of controlling mTORC1-autophagy activity and cell growth continues to expand, we are able to explore how changes in nutrient sensing contribute to the acquisition and maintenance of cellular senescence. Furthermore, while the protective effect of senescence to limit cellular transformation is clear, more recently, the age-related accumulation of these pro-inflammatory senescent cells has been shown to contribute to a decline in organismal fitness. We will further discuss whether dysregulation of nutrient sensing pathways can be targeted to promote senescent cell death which would have important implications for healthy ageing.

Uncoupling the Mitogenic and Metabolic Functions of FGF1 by Tuning FGF1-FGF Receptor Dimer Stability

The recent discovery of metabolic roles for fibroblast growth factor 1 (FGF1) in glucose homeostasis has expanded the functions of this classically known mitogen. To dissect the molecular basis for this functional pleiotropy, we engineered an FGF1 partial agonist carrying triple mutations (FGF1ΔHBS) that diminished its ability to induce heparan sulfate (HS)-assisted FGF receptor (FGFR) dimerization and activation. FGF1ΔHBS exhibited a severely reduced proliferative potential, while preserving the full metabolic activity of wild-type FGF1 in vitro and in vivo. Hence, suboptimal FGFR activation by a weak FGF1-FGFR dimer is sufficient to evoke a metabolic response, whereas full FGFR activation by stable and sustained dimerization is required to elicit a mitogenic response. In addition to providing a physical basis for the diverse activities of FGF1, our findings will impact ongoing drug discoveries targeting FGF1 and related FGFs for the treatment of a variety of human diseases.

Hypoxia-induced EMAP-II transcription in colorectal cancer

Endothelial monocyte-activating polypeptide-II (p431EMAP-II) is a proinflammatory cytokine and a chemoattractant for mononuclear phagocytes and polymorphonuclear leucocytes, found in culture supernatants of many tumour cell lines. It was demonstrated that p43/EMAP-II induces apoptosis in mitogen-stimulated lymphocytes, and suggested that it may be a constituent of a novel immune evasion mechanism employed by tumour cells. Quantitative real-time reverse transcription- polymerase chain reaction (qRT-PCR) analysis for EMAP-II mRNA was performed for colorectal adenocarcinoma cell lines, DLD-1, HT 29; human umbilical vein endothelial cells (HUVEC); and normal colon under normal and hypoxic conditions. Under hypoxic conditions, EMAP-II transcript expression increased up to 22-fold over normoxia in tumour cells, while there was 1-fold increase due to hypoxia in HUVEC and no increase in normal colon. These results demonstrate that EMAP-II transcripts are upregulated in tumour cells in hypoxic conditions and support the notion that EMAP-II plays a complex and important role in human cancer.

Large-scale production of biologically active human keratinocyte growth factor-2

A rapid and efficient expression and purification system has been developed for large-scale production of biologically active recombinant human keratinocyte growth factor-2 (rhKGF-2). The gene encoding human KGF-2 was cloned into the expression vector pET3c and transformed into Escherichia coli BL21(DE3)/pLys S. Under optimal conditions in a 30-l fermentor, the average bacterial yield and the average expression level of rhKGF-2 of three batches were up to 732 g and 32%, respectively. The recombinant protein was purified by cation exchange and heparin-affinity chromatography. One hundred and sixty five milligrams of pure rhKGF-2 was achieved per liter culture. A preliminary biochemical characterization of purified rhKGF-2 was performed by Western blotting and mitogenic activity analysis, and the results demonstrated that purified rhKGF-2 could react with anti-human KGF-2 antibody and stimulate the proliferation of HaCat cells.

Epigenetic regulation of the stem cell mitogen Fgf-2 by Mbd1 in adult neural stem/progenitor cells

Whether and how mechanisms intrinsic to stem cells modulate their proliferation and differentiation are two central questions in stem cell biology. Although exogenous basic fibroblast growth factor 2 (FGF-2/Fgf-2) is commonly used to expand adult neural stem/progenitor cells (NSPCs) in vitro, we do not yet understand the functional significance or the molecular regulation of Fgf-2 expressed endogenously by adult NSPCs. We previously demonstrated that methylated CpG binding protein 1 (MBD1/Mbd1) is a transcriptional repressor of Fgf-2 and is enriched in adult brains. Mbd1 deficiency in mice selectively affected adult neurogenesis and the differentiation of NSPCs. Here we show that an Mbd1 and DNA methylation-mediated epigenetic mechanism regulated the expression of stem cell mitogen Fgf-2 in adult NSPCs. Mbd1 bound to the Fgf-2 promoter and regulates its expression in adult NSPCs. In the absence of functional Mbd1, the Fgf-2 promoter was hypomethylated, and treatment with a DNA methylation inhibitor resulted in increased Fgf-2 expression in adult NSPCs. We further demonstrated that both acute knockdown of Mbd1 or overexpression of Fgf-2 in adult NSPCs inhibited their neuronal differentiation, which could be responsible for the neurogenic deficits observed in Mbd1-deficient mice. These data indicate that intrinsic epigenetic mechanisms play critical roles in the regulation of adult NSPC functions.

Regulation of the orphan receptor TR3 nuclear functions by c-Jun N terminal kinase phosphorylation

The orphan receptor TR3 functions in the nucleus as a transcription factor to negatively or positively regulate gene expression. c-Jun N-terminal kinase (JNK) phosphorylation plays an important role in modulating the nuclear functions of TR3. Although TR3 is the phosphorylation target of JNK, the regulatory mechanism of JNK on TR3 functions remains to be elucidated. Here we showed that JNK activator anisomycin induced TR3 phosphorylation through JNK1 rather than p38 and ERK signals, which is mediated by its upstream factors MAPK kinase 4 and MAPK kinase 7. We also identified the exact phosphorylation site of JNK to be serine 95 at the N terminus of TR3, around which a classical JNK phosphorylation motif exists. Furthermore, we demonstrated that TR3 phosphorylation by JNK coincided with its ubiquitination and degradation, resulting in the loss of its mitogenic activity. Finally, we showed that JNK-induced phosphorylation blocked the DNA binding property of TR3 and hence diminished its transactivation activity. Taken together, our findings revealed a novel cross talk between TR3 and JNK signal pathway and shed light on the mechanism of JNK phosphorylation-dependent regulation on TR3 nuclear functions.

An agglutinin with mitogenic and antiproliferative activities from the mushroom Flammulina velutipes

A hemagglutinin with a molecular mass of 12 kDa was isolated from the fruiting bodies of the mushroom Flammulina velutipes. Its molecular mass is similar to that of the fungal immunomodulatory protein isolated from F. velutipes (FIP-fve) with ice-cold 5% acetic acid and 50 mM 2-mercaptoethanol as extraction medium and to that of the larger 12 kDa subunit of F. velutipes lectin isolated with phosphate buffer as extraction medium. Its hemagglutinating activity cannot be inhibited by a variety of carbohydrates tested. The activity is stable between pH 4 and pH 11. Loss in activity occurred when the temperature is raised to 60 C and 70 C. Activity is indiscernible at and above 80 C. Its N-terminal sequence shows differences from that of FIP-fve. F. velutipes hemagglutinin stimulates [3H-methyl] thymidine uptake by mouse splenocytes. It inhibits proliferation of leukemia L1210 cells with an IC50 of 13 microM.

The mitogenic function of hepatitis B virus X protein resides within amino acids 51 to 140 and is modulated by N- and C-terminal regulatory regions

The hepatitis B virus (HBV) X protein (pX) is implicated in hepatocarcinogenesis by an unknown mechanism. pX variants encoded by HBV genomes found integrated in genomic DNA from liver tumors of patients with hepatocellular carcinoma (HCC) generally lack amino acids 134 to 154. Since deregulation of mitogenic pathways is linked to oncogenic transformation, herein we define the pX region required for mitogenic pathway activation. A series of pX deletions was used to construct tetracycline-regulated pX-expressing cell lines. The activation of the mitogenic pathways by these pX deletions expressed in the constructed cell lines was measured by transient transreporter assays, effects on endogenous cyclin A expression, and apoptosis. Conditional expression of pX51-140 in AML12 clone 4 cell line activates the mitogenic pathways, induces endogenous cyclin A expression, and sensitizes cells to apoptosis, similar to wild-type (WT) pX. By contrast, pX1-115 is inactive, supporting the idea that amino acids 116 to 140 are required for mitogenic pathway activation. Moreover, this pX deletion analysis demonstrates that WT pX function is modulated by two regions spanning amino acids 1 to 78 and 141 to 154. The N-terminal X1-78, expressed via a retroviral vector in WT pX-expressing 4pX-1 cells, coimmunoprecipitates with WT pX, indicating this pX region participates in protein-protein interactions leading to pX oligomerization. Interestingly, pX1-78 interferes with WT pX in mediating mitogenic pathway activation, endogenous gene expression, and apoptosis. The C-terminal pX region spanning amino acids 141 to 154 decreases pX stability, determined by pulse-chase studies of WT pX and pX1-140, suggesting that increased stability of naturally occurring pX variants lacking amino acids 134 to 154 may play a role in HCC development.

Relevance of plant lectins in human cell biology and immunology

Protein-carbohydrate interactions are used for intercellular communication. Mammalian cells are known to bear a variety of glycoconjugates. Lectins, first discovered in plants, are proteins which can specifically bind carbohydrates. Given the high affinity of plant lectins for carbohydrates, they have always been important as molecular tools in the identification, purification and stimulation of specific glycoproteins on human cells. Lectins have provided important clues to the repertoire of carbohydrate structures in animal cells. The discovery of plant lectins gave a great impulse to modern glycobiology. They represent important biochemical reagents for numerous applications in the biomedical field and in research. Sequence determinations and structural characterization helped to understand the mechanism of action in many biologic systems. Plant lectins have been fundamental in human immunological studies because some of them are mitogenic/activating to lymphocytes. Understanding the molecular basis of lectin-carbohydrate interactions and of the intracellular signalling evoked holds promise for the design of novel drugs for the treatment of infectious, inflammatory and malignant diseases. It may also be of help for the structural and functional investigation of glycoconjugates and their changes during physiological and pathological processes.

Crystal structure, catalytic mechanism, and mitogenic properties of Trypanosoma cruzi proline racemase

Amino acid racemases catalyze the stereoinversion of the chiral C alpha to produce the d-enantiomers that participate in biological processes, such as cell wall construction in prokaryotes. Within this large protein family, bacterial proline racemases have been extensively studied as a model of enzymes acting with a pyridoxal-phosphate-independent mechanism. Here we report the crystal structure of the proline racemase from the human parasite Trypanosoma cruzi (TcPRACA), a secreted enzyme that triggers host B cell polyclonal activation, which prevents specific humoral immune responses and is crucial for parasite evasion and fate. The enzyme is a homodimer, with each monomer folded in two symmetric alpha/beta subunits separated by a deep crevice. The structure of TcPRACA in complex with a transition-state analog, pyrrole-2-carboxylic acid, reveals the presence of one reaction center per monomer, with two Cys residues optimally located to perform acid/base catalysis through a carbanion stabilization mechanism. Mutation of the catalytic Cys residues abolishes the enzymatic activity but preserves the mitogenic properties of the protein. In contrast, inhibitor binding promotes the closure of the interdomain crevice and completely abrogates B cell proliferation, suggesting that the mitogenic properties of TcPRACA depend on the exposure of transient epitopes in the ligand-free enzyme.

High-affinity CD25-binding IL-2 mutants potently stimulate persistent T cell growth

We have used directed evolution to construct IL-2 mutants that bind the IL-2 alpha receptor subunit (IL-2Ralpha, CD25) with affinities comparable to that of the IL-15-IL-15 alpha receptor subunit (IL-15Ralpha) interaction. T cells proliferate for up to 6 days following a 30 minute incubation with these IL-2 mutants, which may lead to potential applications for cancer and viral immunotherapy. Several alternative mechanisms have been proposed to explain the contrasting effects of IL-2 and IL-15 on T cell proliferation and death. These IL-2 mutants exhibit T cell growth response-receptor occupancy curves indistinguishable from that for IL-15, suggesting that much of the difference between wild-type IL-2 and IL-15 effects arises simply from their 1000-fold differing affinities for their private alpha receptor subunits.

Generation of inhibitory DNA aptamers against human hepatocyte growth factor

Hepatocyte growth factor (HGF), a multifunctional cytokine, can act on many cell types. It is involved in cancer growth and metastasis by enhancing the motility of cancer cells and stimulating angiogenesis. The development of effective inhibitors for HGF is an important issue in cancer therapy. In this study, we isolated DNA aptamers against human HGF using the systematic evolution of ligands by exponential enrichment method. The selected DNA aptamers had a highly conserved consensus sequence, and could be divided into two major classes (classes I and II). The consensus motif of classes I and II might contribute to the formation of a hairpin loop structure and a G-quartet structure, respectively. These DNA aptamers bound to human HGF with high affinity and specificity. The dissociation constants of typical aptamers H38-15 and H38-21, representative of the two classes, were calculated to be approximately 20 nM. H38-15 and H38-21 inhibited the biological activities of HGF including the stimulation of scattering, migration, and invasion of pancreatic cancer KP-3 cells. Furthermore, both aptamers inhibited HGF-induced tube formation by human umbilical vein endothelial cells. These results suggested that the isolated DNA aptamers will be useful as therapeutic and diagnostic reagents for cancers.

Suppression of metastasis of human pancreatic cancer to the liver by transportal injection of recombinant adenoviral NK4 in nude mice

NK4, a 4-kringle fragment of hepatocyte growth factor (HGF), is an HGF antagonist that also acts as an angiogenesis inhibitor. NK4 strongly inhibits the infiltration, metastasis, and tumor growth of pancreatic cancer. The aim of our study was to evaluate the antitumor effect of adenovirus-mediated NK4 gene transfer to the liver on hepatic metastasis of pancreatic cancer in vivo. We constructed recombinant adenoviral NK4 (Ad-NK4), which encodes a secreted form of human NK4. Intrasplenic injection of Ad-NK4 induced high and relatively maintained expression of NK4 protein in the liver and suppressed the number and growth of metastatic foci in the liver in a nude mouse model. Microscopically, central necrosis was found even in small metastatic foci in Ad-NK4 treated mice. Immunohistochemical analysis of metastatic tumors showed a remarkable decrease in microvessel density and an increase in the number of apoptotic tumor cells after treatment with Ad-NK4. These results indicate that intraportal injection of Ad-NK4 may be a useful therapeutic modality for the clinical control of hepatic metastasis in pancreatic cancer.

Nonviral HVJ (hemagglutinating virus of Japan) liposome-mediated retrograde gene transfer of human hepatocyte growth factor into rat nervous system promotes functional and histological recovery of the crushed nerve

Hepatocyte growth factor (HGF) is well known to be involved in many biological functions, such as organ regeneration and angiogenesis, and to exert neurotrophic effects on motor, sensory, and parasympathetic neurons. In this study, we gave repeated intramuscular injections of the human HGF gene, using nonviral HVJ (hemagglutinating virus of Japan) liposome method, to examine whether transfection of the rat nervous system with this gene is able to exert neurotrophic effects facilitating recovery of a crushed nerve. The expression of HGF protein and HGF mRNA indicated that gene transfer into the nervous system did occur via retrograde axonal transport. At 4 weeks after crush, electrophysiological examination of the crushed nerve showed a significantly shorter mean latency and a significantly greater mean maximum M-wave amplitude with repeated injections of HGF gene. Furthermore, histological findings showed that the mean diameter of the axons, the axon number and the axon population were significantly larger in the group with repeated injections of HGF gene. The above results show that repeated human HGF gene transfer into the rat nervous system is able to promote crushed-nerve recovery, both electrophysiologically and histologically, and suggest that HGF gene transfer has potential for the treatment of crushed nerve.

The aryl hydrocarbon receptor directly regulates expression of the potent mitogen epiregulin

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is known to cause a large number of adverse effects, mediated largely by its binding to the aryl-hydrocarbon receptor (AhR) and subsequent modulation of gene expression. It is thought that AhR mediates these effects through the untimely and disproportionate expression of specific genes. However, the exact mechanism, or the genes involved, through which TCDD leads to these effects is still unknown. This study reports the discovery of a novel target gene, epiregulin, which is regulated by TCDD-activated AhR. Epiregulin is a growth regulator which belongs to the epidermal growth factor (EGF) family. Using real time quantitative PCR (qPCR), it was established that TCDD upregulates epiregulin gene expression. The promoter region of epiregulin has a dioxin responsive element (DRE) 56 nucleotides upstream of the transcription start site, along with three potential Sp1 binding sites. Chromatin immunoprecipitation (ChIP) assays with an anti-AhR antibody showed promoter occupancy upon TCDD treatment. Luciferase reporter assays using a vector harboring the first 125 base pairs of the epiregulin rat promoter revealed an increase in signal on TCDD treatment, which was lost upon mutation of the DRE. Epiregulin and TCDD treatment mediated a dose-dependent increase in primary mouse keratinocyte growth. These results demonstrate that AhR directly increases epiregulin expression, which could play an important role in TCDD mediated tumor promotion observed in rodent models.

Prokineticins (endocrine gland-derived vascular endothelial growth factor and BV8) in the bovine ovary: expression and role as mitogens and survival factors for corpus luteum-derived endothelial cells

A highly vascular endocrine gland, the corpus luteum (CL) is an excellent model for the study of angiogenic factors. Prokineticins (PK-1 and -2), also termed endocrine-gland-derived vascular endothelial growth factor (VEGF) and BV8 are newly identified proteins described as selective angiogenic mitogens. We previously identified PK binding sites, two closely homologous G protein-coupled receptors (PK-R1 and PK-R2) in human and bovine ovarian cells, but their function remained unknown. In this study we examined the presence and effects of PK in CL-derived endothelial and steroidogenic cell types (LEC and LSC, respectively). PK-1 mRNA was identified in CL and follicles by real-time PCR, using primers specific for the bovine PK-1 sequence (retrieved from Bos taurus whole genome shotgun database). PK were potent angiogenic mitogens for LEC; they enhanced cell proliferation, elevated [3H]thymidine incorporation, MAPK activation, and c-jun/fos mRNA expression. The effects of PK proteins on cell survival were examined by nuclear morphology (4',6-diamidino-2-phenylindole dihydrochloride staining), measurement of DNA fragmentation (terminal dUTP nucleotide end labeling assay), and caspase-3 cleavage. Results obtained by these techniques demonstrated that PK protected LEC from serum starvation-induced apoptosis. Stress conditions such as serum withdrawal, TNF-alpha, and hypoxia markedly increased PK-R2 expression, whereas mRNA levels of PK-R1 remained unchanged. These suggest that the antiapoptotic effect of PK-1 on LEC may be mediated via PK-R2. PK-1 increased VEGF mRNA expression by LSC, implying that it could also indirectly, via VEGF, affect luteal angiogenesis. Together, these findings suggest an important role for PK-1 in luteal function by acting as a mitogen and survival factor in LEC.

Suppression of peritoneal implantation of gastric cancer cells by adenovirus vector-mediated NK4 expression

Peritoneal dissemination is the most common mode of metastasis in gastric cancer. We previously reported the importance of milky spots (MS), peritoneal lymphoid tissues, as selective sites of cancer implantation in peritoneal dissemination. In the present study, we first demonstrated that intraperitoneal injection of adenovirus vector encoding the GFP gene into tumor-free nude mice resulted in GFP expression at omental and mesenteric MS; MS macrophages were target cells for adenovirus infection. We confirmed that intraperitoneal injection of adenovirus vector encoding the NK4 gene (AdNK4) resulted in NK4 production localized to the peritoneal cavity, especially the omentum. Adenovirus vector-mediated MS-selective transgene expression was markedly impaired in tumor-bearing mice whose MS had already been replaced by infiltrating cancer cells. However, prior injection of AdNK4 successfully inhibited MS-selective cancer cell implantation, resulting in suppression of peritoneal dissemination and prolongation of survival. Adenovirus vector-mediated MS-selective delivery of a therapeutic gene may prevent peritoneal dissemination of gastric cancer.

Pigment epithelium-derived factor is a pericyte mitogen secreted by microvascular endothelial cells: possible participation of angiotensin II-elicited PEDF downregulation in diabetic retinopathy

Pigment epithelium-derived factor (PEDF) is a natural extracellular component of the retina with neuronal differentiating activity. Decreased levels of PEDF in the mammalian eye have been shown to participate in proliferative diabetic retinopathy. In addition, we have recently found in in vitro experiments that PEDF protected against pericyte apoptosis, the earliest histopathological hallmark of diabetic retinopathy. These observations suggest that the loss of PEDF in the mammalian eye plays an important role in the development and progression of diabetic retinopathy. However, the functional role of endothelial cell (EC)-derived PEDF in pericyte survival and the regulation of PEDF gene expression remain to be elucidated. In this study, we examined the effects of anti-PEDF antibody (Ab) on the viable cell number of cocultured pericytes with microvascular ECs. We further studied the effects of angiotensin II (Ang II) on PEDF gene expression in ECs. Anti-PEDF Ab significantly inhibited the growth-stimulating effects of cocultured ECs on pericytes. Furthermore, Ang II significantly decreased PEDF mRNA levels in ECs, which was completely reversed by an Ang II type 1 receptor blocker, telmisartan. Our present results suggest that PEDF is an EC-derived mitogen or survival factor for retinal pericytes. Suppression by Ang II of the EC-derived PEDF may be involved in exacerbation of diabetic retinopathy in patients with hypertension.

Gallbladder cancer treatment using adenovirus expressing the HGF/NK4 gene in a peritoneal implantation model

Gallbladder cancer cells are stimulated by hepatocyte growth factor (HGF) in vitro and in vivo. We constructed an adenovirus vector, AdCMV.NK4, carrying the HGF antagonist HGF/NK4 (NK4) and evaluated whether or not this vector can suppress the peritoneal implantation of gallbladder cancer in a novel peritoneal injury mouse model. A human gallbladder cancer cell line (GB-d1) and human peritoneal mesothelial cells infected with the adenovirus vector produced a substantial level of NK4 protein. An invasion of GB-d1 cells was determined by a coculture with AdCMV.NK4-infected human mesothelial cells in vitro. Both the invasion and migration of GB-d1 cells were dramatically inhibited by this vector in a multiplicity of infection (MOI)-dependent manner. GB-d1 cells were intraperitoneally injected into the nude mice with peritoneal injury, followed by either AdCMV.NK4 or a control vector (AdCMV.LacZ). The incidence and the size of the metastatic tumor drastically decreased by AdCMV.NK4 (MOI 100: n=4, P<.0001). Real-time PCR analysis revealed a transient elevation of mouse HGF mRNA expression at the peritoneal injury sites. AdCMV.NK4 has been suggested to induce the inhibition of the implantation and growth of gallbladder cancer cells in vivo through its anti-HGF activity, and the use of NK4 gene transfer could be an effective modality for preventing peritoneal metastasis of gallbladder cancer.

AKAP12/Gravin is inactivated by epigenetic mechanism in human gastric carcinoma and shows growth suppressor activity

AKAP12/Gravin, one of the A-kinase anchoring proteins (AKAPs), functions as a kinase scaffold protein and as a dynamic regulator of the beta2-adrenergic receptor complex. However, the biological role of AKAP12 in cancer development is not well understood. The AKAP12 gene encodes two major isoforms of 305 and 287 kDa (designated AKAP12A and AKAP12B, respectively, in this report). We found that these two isoforms are independently expressed and that they are probably under the control of two different promoters. Moreover, both isoforms were absent from the majority of human gastric cancer cells. The results from methylation-specific PCR (MSP) and bisulfite sequencing revealed that the 5' CpG islands of both AKAP12A and AKAP12B are frequently hypermethylated in gastric cancer cells. Treatment with DNA methyltransferase inhibitor and/or histone deacetylase inhibitor efficiently restored the expression of AKAP12 isoforms, confirming that DNA methylation is directly involved in the transcriptional silencing of AKAP12 in gastric cancer cells. Hypermethylation of AKAP12A CpG island was also detected in 56% (10 of 18) of primary gastric tumors. The restoration of AKAP12A in AKAP12-nonexpressing cells reduced colony formation and induced apoptotic cell death. In conclusion, our results suggest that AKAP12A may function as an important negative regulator of the survival pathway in human gastric cancer.

Suppression of tumor growth, invasion and angiogenesis of human gastric cancer by adenovirus-mediated expression of NK4

BACKGROUND

To improve the prognosis of patients with gastric cancer it is important to develop novel treatment modalities targeting the malignant behavior of tumor cells. Concerning this, NK4, which acts as HGF-antagonist and angiogenesis inhibitor, might be a potential therapeutic agent for gastric cancer. The HGF-c-MET pathway plays a pivotal role in gastric tumor growth, invasion, metastasis and angiogenesis. Therefore, the current study investigates whether adenoviral vector-mediated NK4 gene therapy has therapeutic potential for gastric cancer.

METHODS

Expression of HGF and c-MET in normal and (pre-)malignant gastric tissue was studied by immunohistochemistry. The effects of adenoviral vector-mediated expression of NK4 on the biological behavior of gastric cancer cells were studied in vitro and in vivo.

RESULTS

The majority of gastric cancers, i.e. 76%, express c-MET and in all carcinomas HGF is expressed in either tumor or stromal cells. Normal gastric epithelial cells do not express either of these proteins. Transduction of gastric cancer cells with the replication-deficient adenoviral vector AdCMV.NK4 resulted in efficient production and secretion of NK4. Consequently, proliferation, migration and invasion of gastric cancer cells were significantly inhibited. In addition, significantly reduced proliferation of vascular endothelial cells and efficient inhibition of angiogenesis were achieved. Finally, treatment of established human gastric tumor xenografts with AdCMV.NK4 resulted in significant tumor growth delay and significant reduction of intratumoral microvessel density.

CONCLUSIONS

The present study shows that adenoviral vector-mediated expression of NK4 is a promising strategy to treat human gastric cancer by simultaneous interfering with primary tumor growth, metastasis and angiogenesis.

Co-expression of VEGF, c-Met and HGF/SF in secondary pleural tumors

Tumor angiogenesis is influenced by a large number of angiogenic factors among which vascular endothelial growth factor (VEGF) is one of the most important cytokines. Together with hepatocyte growth factor/scatter factor (HGF/SF), c-Met receptor forms a paracrine signaling system. The aim was to study the characterization of the proteins, VEGF, c-Met and HGF/SF with expression pattern and possible co-expression in secondary pleural tumors. Biopsy specimens of the pleural region from 70 patients were chosen and analyzed using immunohistochemistry and in situ hybridization. In the investigated tumors, a marked intracytoplasmic expression, sometimes over-expression of VEGF, c-Met and HGF/SF was detected. This expression was not connected to certain tumor types or a certain histogenetic origin of the tumor. These results indicate a role of these factors in angiogenesis. The synthesis of VEGF and c-Met within the tumor cells was established by in situ hybridization. There was a significant co-expression of VEGF and c-Met/HGF. Thus, autocrine stimulation of these angio-genetically effective systems may be present here. Importantly, the autocrine mechanism between over-expressed c-Met and HGF/SF in malignant tumors, already preferred by other authors, with demonstration of the proteins in the same tumor cells, has to be assumed in the process of pleural metastatic spread. Simultaneous synthesis of these three different proteins is also possible via the plasminogen-urokinase system. VEGF is reported to increase vascular permeability, which in turn causes pleural effusions. The results presented here may be the basis for possible future palliative therapeutical strategies in malignant pleural effusions.

Multiple promoters direct expression of three AKAP12 isoforms with distinct subcellular and tissue distribution profiles

A Kinase Anchoring Protein 12 (AKAP12; also known as src-suppressed C kinase substrate (SSeCKS) and Gravin) is a multivalent anchoring protein with tumor suppressor activity. Although expression of AKAP12 has been examined in a number of contexts, its expression control remains to be elucidated. Herein, we characterize the genomic organization of the AKAP12 locus, its regulatory regions, and the spatial distribution of the proteins encoded by the AKAP12 gene. Using comparative genomics and various wet-lab assays, we show that the AKAP12 locus is organized as three separate transcription units that are governed by non-redundant promoters coordinating distinct tissue expression profiles. The proteins encoded by the three AKAP12 isoforms (designated alpha, beta, and gamma) share >95% amino acid sequence identity but differ at their N termini. Analysis of the targeting of each isoform reveals distinct spatial distribution profiles. An N-terminal myristoylation motif present in AKAP12alpha is shown to be necessary and sufficient for targeted expression of this AKAP12 isoform to the endoplasmic reticulum, a novel subcellular compartment for AKAP12. Our results demonstrate heretofore unrecognized complexity within the AKAP12 locus and suggest a mechanism for genetic control of signaling specificity through distinct regulation of alternately targeted anchoring protein isoforms.

[Suppression of peritoneal implantation by NK4 and its mechanisms]

NK4 suppresses invasion and metastasis of tumor cells by means of dual actions as HGF antagonist and angiogenesis inhibitor. Our previous studies showed that NK4 suppresses the implantation of tumor cells to the peritoneal milky spots (MS) by intraperitoneal injection (i.p.) of adenovirus vector expressing NK4 (Ad-NK4) or NK4 gene-transfected tumor cells. In the present study, we investigated the antitumor mechanisms of NK4 in the suppression of peritoneal implantation. When evaluated by a fluorescent microscopy, a prior injection of Ad-NK4 suppressed peritoneal implantation immediately after the injection of GFP-expressing tumor cells. DNA microarray analyses also demonstrated a reduced expression of some adhesion molecules in NK4 gene-transfected tumor cells as compared to neomycin gene-trasfected cells (control). In the in vitro adhesion assay, the adhesion to some types of the extra cellular matrixs (ECM) was significantly decreased in NK4 gene-transfected cells as compared to the control. These results suggest that NK4 may suppress peritoneal implantation by inhibiting adhesion of tumor cells to ECM around MS.

[Effect of transferred NK4 gene on biological characteristics of human pancreatic cancer cell line SW1990]

BACKGROUND & OBJECTIVE

Hepatocyte growth factor (HGF) plays an important role in the regulation of migration, invasion,and angiogenesis of cancer via the activation of its receptor, c-Met. NK4 is not only an antagonist of HGF but also an angiogenesis inhibitor. The blockade of HGF/c-Met signal pathway and tumor angiogenesis may be a new strategy for cancer treatment. This study was designed to construct eukaryotic expressing vector of NK4 gene, transfer it into human pancreatic cancer cell line SW1990, and observe the effect of transfected NK4 gene on the biological behaviors of SW1990 cells,and its expression in SW1990 cells.

METHODS

The recombinant of pcDNA3/hNK4 plasmid was digested by restrictive enzyme,NK4 gene was cloned into a high effective eukaryotic expressing vector pRC/CMV2, and the recombinant of pRC/CMV2-hNK4 plasmid was transiently introduced into SW1990 cells by lipofectamine. Reverse transcriptase-polymerase chain reaction (RT-PCR),and Western blot were used to detect the expression of NK4 at mRNA, and protein levels,respectively. Migration, and invasion capabilities of the transfected cells were evaluated by Transwall chamber, and Matrigel invasion chamber, respectively.

RESULTS

Expressions of NK4 gene after lipofectamine mediated transfection were observed in SW1990 cells, expected fragment of 453 bp has been amplified by RT-PCR, and Western blot analysis showed positive expression of NK4 protein (50 KDa). NK4 gene had no inhibitory effect on the growth of SW1990 cells (2.2x10(5) vs 2.5x10(5), P >0.05), while it had significantly suppressive effect on the migration and invasion of SW1990 cells driven by HGF or fibroblasts (P< 0.01).

CONCLUSION

NK4 gene transfection may inhibit spreading and invasion of pancreatic cancer cells, which would play an important role in the anti-metastasis therapy for pancreatic cancer.

Expression of pituitary tumor transforming gene (PTTG) and its binding protein in human astrocytes and astrocytoma cells: function and regulation of PTTG in U87 astrocytoma cells

Human securin, pituitary tumor transforming gene (PTTG), is a protooncogene. Here we report expressions of PTTG and its interacting protein, PTTG-binding factor in human astrocytic cells. PTTG expression was higher in malignant cells than in primary astrocytes, whereas PTTG-binding factor was not. Using a xenotransplantable, glioma cell line (U87), we observed that knocking down PTTG mRNA by RNA silencing inhibited serum-induced proliferation by approximately 50%. Furthermore, in U87 cells PTTG expression was up-regulated by promalignant ligands epithelial growth factor (EGF) and TGFalpha, both at the protein and mRNA levels. PTTG induction by EGF receptor (EGFR) ligands could be blocked by the specific EGFR inhibitor, AG1478. Hepatocyte growth factor (HGF) also induced PTTG but to a lesser extent than EGF. Although EGF stimulates HGF secretion in U87 cells, the effect of EGF on PTTG mRNA expression is independent of HGF as neutralizing antibody against HGF failed to abolish EGF-induced up-regulation of PTTG mRNA. PTTG mRNA was unchanged by incubating U87 cells with the promalignant growth factor TGFbeta, apoptosis inducing TNFalpha and ligands for nuclear receptors, such as retinoic acid and retinoid X receptors and peroxisome proliferator-activated receptor-gamma, known for their growth-inhibitory and apoptosis-inducing effects on gliomas. In addition, 17beta-estradiol and Ca2+, known to activate PTTG expression, did not change PTTG mRNA levels in U87 cells. In summary, we show higher PTTG expression in astrocytoma than normal astrocytes and secondly, PTTG is involved in glioma cell growth. Finally, regulation of its expression has glioma-specific features and is selectively regulated by promalignant cytokines including EGFR ligands and HGF.

Suppression of tumor metastasis by NK4 plasmid DNA released from cationized gelatin

NK4, composed of the NH(2)-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as an HGF-antagonist and angiogenesis inhibitor. This study is an investigation to evaluate the feasibility of controlled release formulation of NK4 plasmid DNA in suppressing the tumor growth, and lung metastasis. Biodegradable cationized gelatin microspheres were prepared for the controlled release of an NK4 plasmid DNA. The cationized gelatin microspheres incorporating NK4 plasmid DNA could continuously release plasmid DNA over 28 days as a result of microspheres degradation following the subcutaneous injection. The injection of cationized gelatin microspheres incorporating NK4 plasmid DNA into the subcutaneous tissue significantly prolonged the survival time period of the mice bearing Lewis lung carcinoma tumor. Increases in the tumor volume and the number of lung metastatic nodules of NK4 plasmid DNA release group were suppressed to a significantly greater extent than that of solution-injected group (77.4 and 64.0%, respectively). The number of blood vessels and the apoptosis cells in the tumor tissue were significantly suppressed (80.4%) and increased (127.3%) against free NK4 plasmid DNA-injected group. Thus, the controlled release of NK4 plasmid DNA augmented angiogenesis suppression and apoptosis of tumor cells, which resulted in suppressed tumor growth. We conclude that this controlled release technology is promising to enhance the tumor suppression achieved by gene expression of NK4.

Gastrokine 1 is abundantly and specifically expressed in superficial gastric epithelium, down-regulated in gastric carcinoma, and shows high evolutionary conservation

Through previous large-scale gene expression profiling we identified a transcript that was abundant in normal stomach and down-regulated in gastric cancer. Genes expressed at similar levels included gastrin, MUC5 and pS2, which are important in gastric function. We aimed to characterise this candidate, gastrokine 1 (GKN1), at mRNA, DNA, protein and tissue levels. The gene was studied in human, mouse, rat and cow, and was highly conserved across these species. The mRNA transcripts averaged 750 bp in length. The human, mouse and rat genes all contained six exons spanning 6 kb, and were located on chromosomes 2, 6 and 4 respectively. The full-length translation products were 183-185 amino acids long, reducing to the mature protein of 18 kDa following signal peptide cleavage; these predictions were confirmed by Western blotting. Tagged gastrokine 1 yielded granular cytoplasmic staining with perinuclear accentuation, representing the Golgi apparatus, in keeping with secretion or expression on the extracellular surface. Gene expression in tissues was profiled extensively by Northern blotting, in situ hybridisation and immunohistochemistry. Gastrokine 1 was highly expressed in normal stomach, where it was located in the superficial/foveolar gastric epithelium, but was absent from gastric carcinomas. Outwith the stomach, gastrokine 1 was found only in epithelia showing gastric metaplasia eg Barrett's oesophagus, the ulcer-associated cell lineage and ovarian mucinous neoplasms. In conclusion, we have characterised gastrokine 1, previously known as CA11, AMP-18 or foveolin. Its abundance in, and specificity for, native or metaplastic gastric epithelium, down-regulation in gastric carcinoma and evolutionary conservation suggest that this gene is physiologically important in the stomach. The function of gastrokine 1 is unknown but a role in mucosal protection is postulated.

Suppression of the Progress of Disseminated Pancreatic Cancer Cells by NK4 Plasmid DNA Released from Cationized Gelatin Microspheres

PURPOSE

NK4, composed of the NH2-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as a potent angiogenesis inhibitor. This study is an investigation to evaluate the feasibility of controlled release of NK4 plasmid DNA in suppressing the tumor growth. Controlled release by a biodegradable hydrogel enabled the NK4 plasmid DNA to exert the tumor suppression effects.

METHODS

Biodegradable cationized gelatin microspheres were prepared for the controlled release of an NK4 plasmid DNA. The cationized gelatin microspheres incorporating NK4 plasmid DNA were subcutaneously injected to tumor-bearing mice to evaluate the suppressive effects on tumor angiogenesis and growth.

RESULTS

The cationized gelatin microspheres incorporating NK4 plasmid DNA could release over 28 days as a result of microspheres degradation. The injection of cationized gelatin microspheres incorporating NK4 plasmid DNA into the subcutaneous tissue of mice inoculated with pancreatic cancer cells prolonged their survival time period. An increase in the tumor number was suppressed to a significantly greater extent than free NK4 plasmid DNA. The controlled release of NK4 plasmid DNA suppressed angiogenesis and increased the cell apoptosis in the tumor tissue while it enhanced and prolonged the NK4 protein level in the blood circulation.

CONCLUSIONS

We conclude that the controlled release technology is promising to enhance the tumor suppression effects of NK4 plasmid DNA.

All known in vivo functions of the Oct-2 transcription factor require the C-terminal protein domain

Oct-2, a transcription factor expressed in the B lymphocyte lineage and in the developing CNS, functions through of a number of discrete protein domains. These include a DNA-binding POU homeodomain flanked by two transcriptional activation domains. In vitro studies have shown that the C-terminal activation domain, a serine-, threonine- and proline-rich sequence, possesses unique qualities, including the ability to activate transcription from a distance in a B cell-specific manner. In this study, we describe mice in which the endogenous oct-2 gene has been modified through gene targeting to create a mutated allele, oct-2DeltaC, which encodes Oct-2 protein isoforms that lack all sequence C-terminal to the DNA-binding domain. Surprisingly, despite the retention of the DNA-binding domain and the glutamine-rich N-terminal activation domain, the truncated protein(s) encoded by the oct-2DeltaC allele are unable to rescue any of the previously described defects exhibited by oct-2 null mice. Homozygous oct-2DeltaC/DeltaC mice die shortly after birth, and B cell maturation, B-1 cell self renewal, serum Ig levels, and B lymphocyte responses to in vitro stimulation are all reduced or absent, to a degree equivalent to that seen in oct-2 null mice. We conclude that the C-terminal activation domain of Oct-2 is required to mediate the unique and indispensable functions of the Oct-2 transcription factor in vivo.

ERK1/2 contributes negative regulation to STAT3 activity in HSS-transfected HepG2 cells

Signal transducer and activator of transcription 3 (STAT3) is a recently characterized transcription factor which is essential to liver regeneration. We have previously reported that hepatic stimulator substance (HSS), a novel growth-promoting substance, phosphorylated the epidermal growth factor (EGF) receptors and activated downstream Ras-MAP kinase (extracellular signal-regulated kinases, ERK1/2) cascade. However, whether HSS signal is related to STAT3 pathway remains unclear. The present study is aiming to explore the regulatory effect of activation of ERK1/2 evoked by HSS on STAT3 phosphorylation and STAT3 signaling. Human hepatoma cell line HepG2 was stably transfected with HSS cDNA and HSS expression was measured by Northern blot. The results showed that the transfection of HSS into HepG2 resulted in remarkable increase in cellular proliferation as compared with the non-transfected cells, and it was further proved that the cellular proliferation in the HSS-transfected cells was related to ERK1/2 activation. Treatment of the cells with 50 mM of PD98059, an ERK1/2 specific upstream inhibitor, resulted in ERK1/2 inactivation completely. Inhibition of ERK1/2 allowed the tyrosine of STAT3 to be phosphorylated in a dose-dependent manner to PD98059. Furthermore, transient transfection of STAT3 mutant (STAT3S727A) into HSS-bearing cells could remarkably reverse the inhibitory effect of ERK1/2 on STAT3 phosphorylation. Based upon these results, it is concluded that ERK1/2 negatively modulates STAT3 phosphorylation and this function is dependent on residual serine-727 (S727) of STAT3.

Phospholipids and their derivatives as mitogen and motogen of budding tunicates

In order to discover novel invertebrate cytokines from the budding tunicate, Polyandrocarpa misakiensis, we treated the water-insoluble fraction of tunicate homogenates with trypsin. The extracts showed remarkable activities to promote the growth and motility of tunicate cells. The activities were heat-stable and proteinase K-resistant. After anion exchange chromatography, the activities were eluted with detergents such as 0.1% deoxycholic acid. The Fourier transform infrared spectrum indicated large amounts of fatty acids and phospholipids instead of polypeptides in the extracts. Consistently, the activities were extractable with organic solvents such as chloroform. Long chains of n-3 polyunsaturated free fatty acids (FFA), phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) were the major components in the lipid-soluble fraction. A cDNA for FFA-releasing enzyme phospholipase A(2) (PLA(2)) was cloned. The expression of this gene could be seen in epidermal cells during budding. The recombinant protein, as in the case of the authentic PLA2, preferred PC and PE as substrates, followed by PS and PI. The resultant FFAs only promoted cell growth, while the remaining lysophospholipids stimulated cell motility. The former contained unsaturated fatty acids (C18:1, C20:5, and C22:6) while the latter did not, suggesting that unsaturated fatty acids are responsible for mitogenic activity in tunicate cells. These results show for the first time that phospholipids and their derivatives are bio-mediators promoting cell growth and cell motility in invertebrates.

Hepatoma-derived growth factor is a pulmonary endothelial cell-expressed angiogenic factor

Hepatoma-derived growth factor (HDGF) was previously identified as a developmentally regulated cardiovascular and renal gene that is mitogenic for vascular smooth muscle and aortic endothelial cells. As reciprocal interactions of smooth muscle and endothelial cells are necessary for vascular formation, we examined whether HDGF plays a role in angiogenesis. According to immunohistochemistry, HDGF was highly expressed in endothelial cells of nonmuscularized, forming blood vessels of the fetal lung. HDGF was also expressed in endothelial cells of small (20 microm) mature arteries and veins. By Western immunoblotting, HDGF was highly expressed by human pulmonary microvascular endothelial cells in vitro. Adenoviral overexpression of HDGF was mitogenic for human pulmonary microvascular endothelial cells in serum-free medium, stimulating a 1.75-fold increase in bromodeoxyuridine (BrdU) uptake and a twofold increase in cell migration. With the chick chorioallantoic membrane (CAM), a biologic assay for angiogenesis, exogenous recombinant HDGF significantly stimulated blood vessel formation and a dose-dependent reorganization of cells within the CAM into a more compact, linear alignment reminiscent of tube formation. According to double immunostaining for endothelial cells with a transforming growth factor-betaII receptor antibody and BrdU as a marker of cell proliferation, exogenous HDGF selectively stimulated endothelial cell BrdU uptake. HDGF also activated specific ERK1/2 signaling and did not overlap with VEGF SAPK/JNK, Akt-mediated pathways. We conclude that HDGF is a highly expressed vascular endothelial cell protein in vivo and is a potent endothelial mitogen and regulator of endothelial cell migration by mechanisms distinct from VEGF.

Sonic hedgehog functions as a mitogen during bell stage of odontogenesis

Epithelial-mesenchymal interactions are required for tissue growth and gene expression patterns during odontogenesis. We showed previously that Sonic hedgehog (SHH) is detectable in both dental epithelium and mesenchyme, while Shh transcripts are present in dental epithelium only, suggesting that SHH functions as an autocrine signal in epithelium and a paracrine signal in mesenchyme. This hypothesis was tested here. We found by in situ hybridization that the SHH autocrine receptor Ptch-2 is indeed expressed in dental epithelium whereas the paracrine receptor Ptc is expressed in mesenchyme. Bovine bell stage tooth germs were microsurgically separated into epithelial and mesenchymal portions and the resulting tissue fragments were organ-cultured. In epithelium fragments cultured by themselves, gene expression of Shh and Gli-1 (a putative transcriptional mediator of hedgehog signaling) was significantly decreased in both inner dental epithelium and stratum intermedium layers; this was accompanied by a sharp drop in epithelial cell proliferation. However, in companion control tissue fragments containing both epithelium and mesenchyme, Shh and Gli-1 expression as well as cell proliferation were maintained. Treatment of dental epithelial or mesenchymal cell populations in monolayer cultures with exogenous recombinant SHH stimulated cell proliferation. Together, the data provide clear evidence that Shh is synthesized by dental epithelium, reaches the underlying mesenchyme, and appears to act as an autocrine mitogen for epithelial cells and a paracrine mitogen for mesenchymal cells, thus exerting crucial functions in tooth germ growth, morphogenesis, and tissue-tissue interactions of bell stage of odontogenesis.

Fibroblast growth factor 17 is over-expressed in human prostate cancer

Over-expression of fibroblast growth factor 8 (FGF8) in human prostate cancer is associated with clinically aggressive disease. Among different members of the FGF family, FGF17 and FGF8 share high sequence homology and have similar patterns of expression during embryogenesis. In this study, the clinical significance of FGF17 expression and its in vitro function in prostate cancer cells were tested. Forty resected prostate specimens from patients with benign prostatic hyperplasia (BPH, n = 12) and prostate cancer (CaP, n = 28; Gleason sum scores 3-10) were studied using semi-quantitative RT-PCR. In addition, 85 cases of CaP (Gleason sum scores 5-9) and 20 cases of BPH were examined using immunohistochemistry and findings were correlated with clinical parameters. In vitro experiments using prostate cancer cell lines examined the functional significance of FGF17 in prostate cancer. These studies revealed a significant linear correlation between increasing Gleason sum scores and FGF17 expression using both immunohistochemistry (p < 0.0001, rho = 0.99) and RT-PCR (p = 0.008, rho = 0.99). Immunohistochemistry demonstrated upregulation of FGF17 in CaP compared with BPH (p < 0.0001) and, when comparing high-grade CaP (Gleason sum score 7-10) with BPH, RT-PCR showed a fourfold upregulation of FGF17 mRNA expression (p < 0.0001). Men with tumours displaying high levels of FGF17 expression had a worse outcome on survival analysis (p = 0.044) and a higher risk of progression with metastases (p < 0.0001). Proliferation assays showed low-dose recombinant (r) FGF17 (1 ng/ml) to be a more potent mitogen than rFGF1 and rFGF8 in prostate cancer cell lines (LNCaP, DU145, and PC3M) (p < 0.001). Furthermore, FGF8 was shown to induce expression of FGF17 in these cell lines. These data support a role for FGF17, and a model of co-expression of multiple FGFs, with FGF17 as a potential mediator of FGF8 function, in human prostate carcinogenesis.

DNA oligonucleotide microarray technology identifies fisp-12 among other potential fibrogenic genes following murine unilateral ureteral obstruction (UUO): Modulation during epithelial-mesenchymal transition

BACKGROUND

Tubulointerstitial inflammation and fibrosis are pathologic hallmarks of end-stage renal disease (ESRD). Here we have used DNA microarray technology to monitor the transcriptomic responses to murine unilateral ureteral obstruction (UUO) with a view to identifying molecular modulators of tubulointerstitial fibrosis.

METHODS

Using Affymetrix Mu74Av2 microarrays, gene expression 4 and 10 days postobstruction was investigated relative to control contralateral kidneys. Candidate profibrogenic genes were further investigated in epithelial cells undergoing epithelial to mesenchymal transition (EMT) in vitro.

RESULTS

mRNA levels for 1091 gene/EST sequences, of a total of 12,488 displayed on the microarray, were altered twofold or greater by days 4 and 10 postobstruction compared to contralateral control kidneys. Genes were categorised into functional groups, including modulators of cytoskeletal and extracellular matrix metabolism, cell growth, signalling, and transcription/translational events. Among the potentially profibrogenic genes, whose mRNA levels were increased after UUO, were fibroblast-inducible secreted protein (fisp-12), the murine homologue of connective tissue growth factor (CTGF), collagen XVIIIalpha1, secreted protein acidic and rich in cysteine (SPARC), and src-suppressed C-kinase substrate (SSeCKS). A sustained increase in fisp-12 mRNA level was observed during EMT induced by transforming growth factor-beta1 (TGF-beta1) and epidermal growth factor (EGF).

CONCLUSION

Altered gene expression in murine UUO has been demonstrated. Increased expression of fisp-12, SPARC, and SSeCKS has been shown in response to TGF-beta1 treatment and during EMT, suggesting that these genes may offer potential therapeutic targets against tubulointerstitial fibrosis.

Expression and mitogenic effect of fibroblast growth factor-9 in human endometriotic implant is regulated by aberrant production of estrogen

Fibroblast growth factor-9 (FGF-9) is a steroid-regulated mitogen and survival factor for nerve and mesenchymal cells. In the current study, we determined the expression pattern and functional roles of FGF-9 in the ectopic endometriotic lesions. We found that FGF-9 and its receptors were effectively expressed by ectopic endometriotic tissues. The expression of FGF-9 was greater in the early stage of endometriosis, compared with the severe stage, which is consistent with concentration of 17 beta-estradiol in the peritoneal fluid of women with endometriosis. In addition, expression of FGF-9 in ectopic endometriotic stromal cell was inhibited by treatment with ICI 182,870 indicating it is likely regulated by estrogen in an autocrine manner. Administration of 17 beta-estradiol induced FGF-9, FGF receptor 2IIIc, and FGF receptor 3IIIc expression in endometriotic stromal cells. Concordant with this result, treatment of endometriotic stromal cells with 4-hydroxyandrostenedione (an aromatase inhibitor) or ICI 182,870 inhibited their proliferation, and that was reversed by coadministration with 17 beta-estradiol or FGF-9. In conclusion, expression of FGF-9 in endometriotic stromal cells is associated with aberrant production of estrogen. The capability of proliferation possessed by endometriotic stromal cell during menstruation when ovarian 17 beta-estradiol is in the nadir may be mediated, at least in part, by autocrined estrogen-stimulated expression of FGF-9 and its receptors.

Functional analysis of the TCR binding domain of toxic shock syndrome toxin-1 predicts further diversity in MHC class II/superantigen/TCR ternary complexes

Superantigens (SAGs) aberrantly alter immune system function through simultaneous interaction with lateral surfaces of MHC class II molecules on APCs and with particular variable regions of the TCR beta-chain (Vbeta). To further define the interface between the bacterial SAG toxic shock syndrome toxin-1 (TSST-1) and the TCR, we performed alanine scanning mutagenesis within the putative TCR binding region of TSST-1 along the central alpha helix adjacent to the N-terminal alpha helix and the beta7-beta9 loop as well as with two universally conserved SAG residues (Leu(137) and Tyr(144) in TSST-1). Mutants were analyzed for multiple functional activities, and various residues appeared to play minor or insignificant roles in the TCR interaction. The locations of six residues (Gly(16), Trp(116), Glu(132), His(135), Gln(136), and Gln(139)), each individually critical for functional activity as well as direct interaction with the human TCR Vbeta2.1-chain, indicate that the interface occurs in a novel region of the SAG molecule. Based on these data, a model of the MHC/TSST-1/TCR ternary complex predicts similarities seen with other characterized SAGs, although the CDR3 loop of Vbeta2.1 is probably involved in direct SAG-TCR molecular interactions, possibly contributing to the TCR Vbeta specificity of TSST-1.

A novel mitogenic protein that is highly expressed in cells of the gastric antrum mucosa

Human and pig cDNAs for a novel stomach protein, the product of a gene expressed at high levels specifically in cells of the antrum mucosa, have been characterized. The general exon/intron structure of the genomic DNA is conserved in humans and mice. The predicted protein sequences of the human and mouse mRNAs contain 185 and 184 amino acids, respectively. The protein isolated from pig antral extracts has an NH2 terminus consistent with cleavage of a 20-amino acid signal peptide. Human cDNA was expressed in E. coli to generate a protein antigen for antibody production. The antibodies detected polypeptides of approximately 18 kDa in antrum extracts from all mammalian species tested. Immunocytochemistry located antrum mucosal protein (AMP)-18 to surface mucosal cells of the mouse antrum and, specifically, to secretion granules, suggesting that it is cosecreted with mucins. Antrum extracts and recombinant human AMP-18 exhibit growth-promoting activity on epithelial cells that can be blocked by the specific antisera. We suggest that AMP-18 is a "gastrokine" that maintains the integrity of the gastric mucosal epithelium.

RECOGNITION OF THE CLINICAL SIGNS AND SYMPTOMS OF JOUBERT SYNDROME

Joubert Syndrome is a rare, autosomal recessive disorder that affects the cerebellum and brain stem. It presents with a distinct respiratory pattern and profound tachypnea in the newborn period. This article provides an overview of the condition and discusses the embryologic origins of this syndrome. A focused history and systematic physical assessment provide a step-by-step guide to enhance the early recognition of clinical signs and symptoms of this disorder. A series of clinical photographs and a brief case report offer insight into the classic presentation of this uncommon disorder. The diagnosis of Joubert syndrome is confirmed with magnetic resonance imaging, which reveals a classic neuroradiologic finding, characterized as the molar tooth sign. A discussion of the range of developmental outcomes and complex multispecialty care and intensive support that these infants and their families require is also provided.

Massive liver growth in mice induced by systemic interleukin 6 administration

The multifunctional cytokine interleukin 6 (IL-6) is expressed in a wide variety of disease states and pathologic processes. Mice deficient in IL-6 display abnormal and delayed liver regeneration and repair. Currently, IL-6 is thought to influence liver growth indirectly by priming hepatocytes to respond to growth factors such as hepatocyte growth factor (HGF) by inducing expression of HGF and by inhibiting hepatocyte apoptosis, as distinct from the direct mitotic effects of IL-6 on myeloid and other cell types. Here, we show that systemic administration of IL-6 using CHO cell tumors in nude mice results in dramatic hepatomegaly and hepatocyte hyperplasia in the absence of liver injury. Liver mass and liver to body mass ratios increased to 2 to 3 times normal because of proliferation of hepatocytes. Liver growth was associated with high levels of serum IL-6 and with activation of the IL-6-signaling pathway, including increased expression of IL-6 receptor-alpha/gp80, activation of the signal transducer and activator of transcription-3 (STAT-3), and mitogen-activated protein kinase (MAPK/ERK)-signaling pathways and induction of downstream target genes, including c-myc. HGF receptor and transforming growth factor alpha (TGF-alpha)/epidermal growth factor (EGF) receptor activation were decreased in hypertrophied livers, suggesting that IL-6-induced liver growth was independent of these known hepatocyte mitotic pathways. In conclusion, we suggest that IL-6 may function as a direct hepatic mitogen in vivo and, furthermore, that IL-6 warrants closer examination as a potent liver growth factor with potential clinical utility for increasing liver mass following injury.

SSeCKS regulates angiogenesis and tight junction formation in blood-brain barrier

The blood-brain barrier (BBB) is essential for maintaining brain homeostasis and low permeability. BBB maintenance is important in the central nervous system (CNS) because disruption of the BBB may contribute to many brain disorders, including Alzheimer disease and ischemic stroke. The molecular mechanisms of BBB development remain ill-defined, however. Here we report that src-suppressed C-kinase substrate (SSeCKS) decreases the expression of vascular endothelial growth factor (VEGF) through AP-1 reduction and stimulates expression of angiopoietin-1 (Ang-1), an antipermeability factor in astrocytes. Conditioned media from SSeCKS-overexpressing astrocytes (SSeCKS-CM) blocked angiogenesis in vivo and in vitro. Moreover, SSeCKS-CM increased tight junction proteins in endothelial cells, consequently decreasing [3H]sucrose permeability. Furthermore, immunoreactivity to SSeCKS gradually increased during the BBB maturation period, and SSeCKS-expressing astrocytes closely interacted with zonula occludens (ZO)-1-expressing blood vessels in vivo. Collectively, our results suggest that SSeCKS regulates BBB differentiation by modulating both brain angiogenesis and tight junction formation.

Zinc-binding sites in the N terminus of Mycoplasma arthritidis-derived mitogen permit the dimer formation required for high affinity binding to HLA-DR and for T cell activation

Zinc-dependent superantigens can be divided into two subfamilies based on how they use zinc ions for interactions with major histocompatibility complex (MHC) class II molecules. Members of the first subfamily use zinc ions for interactions with histidine 81 on the beta-chain of MHC class II molecules, whereas members of the second subfamily use zinc ions for dimer formation. The zinc-binding motif is located in the C terminus of the molecule in both subfamilies. While our recent studies with Mycoplasma arthritidis-derived mitogen (MAM) have provided the first direct evidence demonstrating the binding to MHC class II molecules in a zinc-dependent manner, it still not known how zinc coordinates the interaction. Data presented here show that the zinc ion is mainly required to induce MAM/MAM dimer formation. Residues in the N terminus of MAM are involved in dimer formation and MHC class II binding, while histidine 14 and aspartic acid 31 of the MAM sequence are the major residues mediating MAM/MAM dimerization. Zinc-induced dimer formation is necessary for MAM binding, MHC class II-induced cell-cell adhesion, and efficient T cell activation. Together these results depict the unique mode of interaction of MAM in comparison with other superantigens.

Identification of a serine protease involved with the regulation of adrenal growth

The adrenal cortex is a dynamic organ in which the cells of the outer cortex continually divide. It is well known that this cellular proliferation is dependent on constant stimulation from peptides derived from the ACTH precursor pro-opiomelanocortin (POMC) because disruption of pituitary corticotroph function results in rapid atrophy of the gland. Previous results from our laboratory have suggested that the adrenal mitogen is a fragment derived from the N-terminal of POMC not containing the gamma-MSH sequence. Because such a peptide is not generated during processing of POMC in the pituitary, we proposed that the mitogen is generated from circulating pro-gamma-MSH by an adrenal protease. Using degenerate oligonucleotides, we identified a secreted serine protease expressed by the adrenal gland that we named adrenal secretory protease (AsP). In the adrenal cortex, expression of AsP is limited to the outer zona glomerulosa/fasciculata, the region where cortical cells are believed to be derived, and is significantly up-regulated during compensatory growth. Y1 adrenocortical cells transfected with a vector expressing an antisense RNA (and thus having reduced levels of endogenous AsP) were found to grow slower than sense controls while also losing their ability to utilize exogenous pro-gamma-MSH in the media supporting a role for AsP in adrenal growth. Digestion of an N-POMC peptide substrate encompassing the residues around the dibasic cleavage site at positions 49/50 with affinity-purified AsP showed cleavage not to occur at the dibasic site but two residues downstream leading us to propose the identity of the adrenal mitogen to be N-POMC (1-52).

Mouse endocrine gland-derived vascular endothelial growth factor: a distinct expression pattern from its human ortholog suggests different roles as a regulator of organ-specific angiogenesis

We recently described human endocrine gland-derived vascular endothelial growth factor (EG-VEGF) as an endothelial cell mitogen with a novel selective activity and an expression pattern essentially limited to steroidogenic glands. Herein we present the identification and characterization of the mouse ortholog. The mouse cDNA and predicted amino acid sequences are, respectively, 86% and 88% identical with the human. Surprisingly, the mouse EG-VEGF transcript is predominantly expressed in liver and kidney. A comparison of human and mouse EG-VEGF promoter sequences revealed a potential binding site for NR5A1, which is known to be a pivotal element for steroidogenic-specific transcription, in the human but not mouse promoter. In situ hybridization studies localized expression of mouse EG-VEGF mRNA to hepatocytes and renal tubule cells. Interestingly, capillary endothelial cells in these sites share several common structural features with those found in steroidogenic glands. Within liver and kidney, EG-VEGF receptor expression was largely restricted to endothelial cells. Mouse EG-VEGF promoted proliferation and survival of endothelial cells. We propose that mouse EG-VEGF, like human EG-VEGF, plays a role in regulating the phenotype and growth properties of endothelial cells within distinct capillary beds.