The transcription factor TTF-1 is expressed at the onset of thyroid and lung morphogenesis and in restricted regions of the foetal brain

TTF-1, a homeodomain-containing transcription factor, which is required for the specific expression of the thyroglobulin and thyroperoxidase gene promoters in differentiated thyroid cell lines, is expressed at the very beginning of rat thyroid differentiation. TTF-1 mRNA is detected in the endodermal cells of the thyroid rudiment in the rat embryo and precedes the expression of the two known target genes by 5 days. No delay is observed between the appearance of TTF-1 mRNA and protein, which shows a clear nuclear localization. In the adult thyroid, TTF-1 is present only in the endoderm-derived follicular cells. Two additional domains of expression of TTF-1 have been observed, the lung and restricted areas of the brain. In the lung, TTF-1 mRNA and protein are also present at the earliest stages of differentiation and are later confined to the bronchial epithelium. In the brain, TTF-1 appears to be restricted to structures of diencephalic origin, including the developing neurohypophysis. The early detection of TTF-1 in the endodermal cells of the thyroid and lung anlage and in restricted neuroblast populations indicates that TTF-1 may have a role in cell determination in these three systems and that additional mechanisms may be involved in the activation of thyroid-specific gene expression.

Interleukin 6 is required for the development of collagen-induced arthritis

Interleukin-6 (IL-6) is overproduced in the joints of patients with rheumatoid arthritis (RA) and, based on its multiple stimulatory effects on cells of the immune system and on vascular endothelia, osteoclasts, and synovial fibroblasts, is believed to participate in the development and clinical manifestations of this disease. In this study we have analysed the effect of ablating cytokine production in two mouse models of arthritis: collagen-induced arthritis (CIA) in DBA/1J mice and the inflammatory polyarthritis of tumor necrosis factor alpha (TNF-alpha) transgenic mice. IL-6 was ablated by intercrossing an IL-6 null mutation into both arthritis-susceptible genetic backgrounds and disease development was monitored by measuring clinical, histological, and biochemical parameters. Two opposite responses were observed; while arthritis in TNF-alpha transgenic mice was not affected by inactivation of the IL-6 gene, DBA/1J, IL-6(-/-) mice were completely protected from CIA, accompanied by a reduced antibody response to type II collagen and the absence of inflammatory cells and tissue damage in knee joints. These results are discussed in the light of the present knowledge of cytokine networks in chronic inflammatory disorders and suggest that IL-6 receptor antagonists might be beneficial for the treatment of RA.

Interleukin 6 causes growth impairment in transgenic mice through a decrease in insulin-like growth factor-I. A model for stunted growth in children with chronic inflammation

Stunted growth is a major complication of chronic inflammation and recurrent infections in children. Systemic juvenile rheumatoid arthritis is a chronic inflammatory disorder characterized by markedly elevated circulating levels of IL-6 and stunted growth. In this study we found that NSE/hIL-6 transgenic mouse lines expressing high levels of circulating IL-6 since early after birth presented a reduced growth rate that led to mice 50-70% the size of nontransgenic littermates. Administration of a monoclonal antibody to the murine IL-6 receptor partially reverted the growth defect. In NSE/hIL-6 transgenic mice, circulating IGF-I levels were significantly lower than those of nontransgenic littermates; on the contrary, the distribution of growth hormone pituitary cells, as well as circulating growth hormone levels, were normal. Treatment of nontransgenic mice of the same strain with IL-6 resulted in a significant decrease in IGF-I levels. Moreover, in patients with systemic juvenile rheumatoid arthritis, circulating IL-6 levels were negatively correlated with IGF-I levels. Our findings suggest that IL-6-mediated decrease in IGF-I production represents a major mechanism by which chronic inflammation affects growth.

Lymphoproliferative disorder and imbalanced T-helper response in C/EBP beta-deficient mice

C/EBP beta is considered a key element of interleukin-6 (IL-6) signalling as well as an important transcriptional regulator of the IL-6 gene itself. We describe here how mice lacking C/EBP beta develop a pathology similar to mice overexpressing IL-6 and nearly identical to multicentric Castleman's disease in human patients, with marked splenomegaly, peripheral lymphadenopathy and enhanced haemopoiesis. Humoral, innate and cellular immunity are also profoundly distorted, as shown by the defective activation of splenic macrophages, the strong impairement of IL-12 production, the increased susceptibility to Candida albicans infection and the altered T-helper function. Our data show that C/EBP beta is crucial for the correct functional regulation and homeostatic control of haemopoietic and lymphoid compartments.

Efficient and regulated erythropoietin production by naked DNA injection and muscle electroporation

We show that an electric treatment in the form of high-frequency, low-voltage electric pulses can increase more than 100-fold the production and secretion of a recombinant protein from mouse skeletal muscle. Therapeutical erythopoietin (EPO) levels were achieved in mice with a single injection of as little as 1 microgram of plasmid DNA, and the increase in hematocrit after EPO production was stable and long-lasting. Pharmacological regulation through a tetracycline-inducible promoter allowed regulation of serum EPO and hematocrit levels. Tissue damage after stimulation was transient. The method described thus provides a potentially safe and low-cost treatment for serum protein deficiencies.

Regional expression of the homeobox gene Nkx-2.2 in the developing mammalian forebrain

A novel mouse homeobox-containing gene, Nkx-2.2, has been isolated. Nkx-2.2 is a member of a family of genes whose homeodomains are homologous to that of the Drosophila NK-2 gene. Nkx-2.2 transcripts are found in localized domains of the brain during mouse embryogenesis. Nkx-2.2 expression in the brain abuts and partially overlaps with the expression domains of two other related homeobox-containing genes, TTF-1 and Dlx. The expression domains of the three genes in the developing prosencephalon coincide with anatomical boundaries, particularly apparent in the diencephalon. This result raises the possibility that these genes may specify regional differentiation of the developing diencephalon into its anatomically and functionally defined subregions. Nkx-2.2 may be involved in specifying diencephalic neuromeric boundaries.

Human embryonic hemopoiesis. Kinetics of progenitors and precursors underlying the yolk sac----liver transition

Human embryonic development involves transition from yolk sac (YS) to liver (L) hemopoiesis. We report the identification of pluripotent, erythroid, and granulo-macrophage progenitors in YS, L, and blood from human embryos. Furthermore, comprehensive studies are presented on the number of hemopoietic progenitors and precursors, as well as of other cell types, in YS, L, and blood at precisely sequential stages in embryos and early fetuses (i.e., at 4.5-8 wk and 9-10 wk postconception, respectively). Our results provide circumstantial support to a monoclonal hypothesis for human embryonic hemopoiesis, based on migration of stem and early progenitor cells from a generation site (YS) to a colonization site (L) via circulating blood. The YS----L transition is associated with development of the differentiation program in proliferating stem cells: their erythroid progeny shows, therefore, parallel switches of multiple parameters, e.g., morphology (megaloblasts----macrocytes) and globin expression (zeta----alpha, epsilon----gamma).

Ciliary neurotrophic factor corrects obesity and diabetes associated with leptin deficiency and resistance

Receptor subunits for the neurocytokine ciliary neurotrophic factor (CNTF) share sequence similarity with the receptor for leptin, an adipocyte-derived cytokine involved in body weight homeostasis. We report here that CNTF and leptin activate a similar pattern of STAT factors in neuronal cells, and that mRNAs for CNTF receptor subunits, similarly to the mRNA of leptin receptor, are localized in mouse hypothalamic nuclei involved in the regulation of energy balance. Systemic administration of CNTF or leptin led to rapid induction of the tis-11 primary response gene in the arcuate nucleus, suggesting that both cytokines can signal to hypothalamic satiety centers. Consistent with this idea, CNTF treatment of ob/ob mice, which lack functional leptin, was found to reduce the adiposity, hyperphagia, and hyperinsulinemia associated with leptin deficiency. Unlike leptin, CNTF also reduced obesity-related phenotypes in db/db mice, which lack functional leptin receptor, and in mice with diet-induced obesity, which are partially resistant to the actions of leptin. The identification of a cytokine-mediated anti-obesity mechanism that acts independently of the leptin system may help to develop strategies for the treatment of obesity associated with leptin resistance.

IL-6 expression in neurons of transgenic mice causes reactive astrocytosis and increase in ramified microglial cells but no neuronal damage

Growing evidence suggests that aberrant production of inflammatory cytokines within the central nervous system (CNS) contributes to the development of pathological conditions. To test the cause-effect relationship between the overproduction of interleukin-6 (IL-6) in the CNS and the onset of neuropathological changes, we have generated transgenic mice in which human IL-6 expression has been targeted to the neurons by using the rat neuron-specific enolase promoter. These mice develop reactive astrocytosis and an increase in ramified microglial cells but do not show histological or behavioural signs of neuron damage at the light microscope level. We thus conclude that a constant release of human IL-6 by neuronal subpopulations in mice is sufficient to activate cells potentially capable of modulating the local immune response, but at the same time is compatible with normal neuron functions.

LFB3, a heterodimer-forming homeoprotein of the LFB1 family, is expressed in specialized epithelia

We have cloned and characterized a mouse cDNA coding for LFB3, a DNA binding protein containing an extra-large homeodomain. The first 315 amino acids of LFB3 are highly homologous to the DNA binding domain of LFB1, a regulatory protein involved in the expression of several liver-specific genes. LFB3 is a transcriptional activator which binds to DNA as a dimer and forms heterodimers with LFB1 both in vitro and in vivo. However, LFB3 expression seems not to be directly correlated with the liver-specific phenotype, since it is detected in dedifferentiated hepatoma cell lines which express neither LFB1 nor several liver-specific genes. LFB3 expression starts before that of LFB1 during mouse and rat development, and is strongly increased upon retinoic acid induced differentiation of F9 embryonic carcinoma cells. LFB3 and LFB1 are expressed in the epithelial component of many organs of endodermal and mesodermal origin, suggesting that they may play a more general role associated with the differentiation of specialized epithelia.

Coexpression of IL-6 and soluble IL-6R causes nodular regenerative hyperplasia and adenomas of the liver

Studies with tumor necrosis factor p55 receptor- and interleukin-6 (IL-6)-deficient mice have shown that IL-6 is required for hepatocyte proliferation and reconstitution of the liver mass after partial hepatectomy. The biological activities of IL-6 are potentiated when this cytokine binds soluble forms of its specific receptor subunit (sIL-6R) and the resulting complex interacts with the transmembrane signaling chain gp130. We show here that double transgenic mice expressing high levels of both human IL-6 and sIL-6R under the control of liver-specific promoters spontaneously develop nodules of hepatocellular hyperplasia around periportal spaces and present signs of sustained hepatocyte proliferation. The resulting picture is identical to that of human nodular regenerative hyperplasia, a condition frequently associated with immunological and myeloproliferative disorders. In high expressors, hyperplastic lesions progress with time into discrete liver adenomas. These data strongly suggest that the IL-6/sIL-6R complex is both a primary stimulus to hepatocyte proliferation and a pathogenic factor of hepatocellular transformation.

Discovery of a basaltic asteroid in the outer main belt

Visible and near-infrared spectroscopic observations of the asteroid 1459 Magnya indicate that it has a basaltic surface. Magnya is at 3. 15 astronomical units (AU) from the sun and has no known dynamical link to any family, to any nearby large asteroid, or to asteroid 4 Vesta at 2.36 AU, which is the only other known large basaltic asteroid. We show that the region of the belt around Magnya is densely filled by mean-motion resonances, generating slow orbital diffusion processes and providing a potential mechanism for removing other basaltic fragments that may have been created on the same parent body as Magnya. Magnya may represent a rare surviving fragment from a larger, differentiated planetesimal that was disrupted long ago.

LFB1 and LFB3 homeoproteins are sequentially expressed during kidney development

LFB1 (HNF-1/HNF-1 alpha/APF) and LFB3 (vHNF-1/HNF-1 beta) are two homeoproteins involved in the transcriptional regulation of several liver-specific genes. Both genes are expressed in the polarized epithelia of a wide range of tissues, including liver, the digestive tract and kidney. We have analyzed the expression pattern of LFB1 and LFB3 in the developing rat kidney by in situ hybridization. Our results show that LFB3 transcripts can be detected in mesoderm-derived cells as soon as they are induced to differentiate into a polarized epithelium, while LFB1 transcripts appear only at a later stage when the three different segments of the nephron become apparent. LFB1 transcripts are restricted to the proximal and distal tubules, whereas LFB3 is also detected in the collecting ducts. Neither LFB1 nor LFB3 are expressed in the glomeruli or in the transition epithelia of the ureters and of the urinary bladder, none of which are involved in active transport mechanisms. The sequential activation of these two genes is also observed in transfilter organ cultures of nephrogenic mesenchyme at different stages after induction. This expression pattern suggests that LFB3 and LFB1 play a role in two critical stages of the developmentally regulated conversion of the nephric mesenchyme into a polarized epithelium: the early inductory phase (LFB3) and the postinductory phase (LFB1+LFB3).

Differential splicing of the GHF1 primary transcript gives rise to two functionally distinct homeodomain proteins

The POU domain protein GHF-1 has a critical role in generation, proliferation and phenotypic expression of three pituitary cell types. GHF-1 functions in part by binding to and transactivating the promoters of both the growth hormone (GH) and prolactin (PRL) genes and that of the GHF1 gene itself. We describe a naturally occurring isoform of GHF-1, GHF-2, in which an additional 26 amino acids are inserted into the activation domain of the protein as a result of alternative splicing. GHF-2 retains the DNA binding activity of GHF-1 and can activate the GH promoter but has lost the ability to activate the PRL and GHF1 promoters. These results suggest that GHF-2 may function in differential target gene activation during differentiation of the somatotrophic lineage. Both GHF-1 and GHF-2 transcripts are specifically expressed in the anterior pituitary. Analysis of the genomic GHF1 gene shows that most of the distinct functional domains of GHF-1 (and GHF-2) are encoded by separate exons. Gene segment duplication and exon shuffling may have contributed to the evolution of this cell type-specific transcriptional regulatory gene.

Charon's size and an upper limit on its atmosphere from a stellar occultation

Pluto and its satellite, Charon (discovered in 1978; ref. 1), appear to form a double planet, rather than a hierarchical planet/satellite couple. Charon is about half Pluto's size and about one-eighth its mass. The precise radii of Pluto and Charon have remained uncertain, leading to large uncertainties on their densities. Although stellar occultations by Charon are in principle a powerful way of measuring its size, they are rare, as the satellite subtends less than 0.3 microradians (0.06 arcsec) on the sky. One occultation (in 1980) yielded a lower limit of 600 km for the satellite's radius, which was later refined to 601.5 km (ref. 4). Here we report observations from a multi-station stellar occultation by Charon, which we use to derive a radius, R(C) = 603.6 +/- 1.4 km (1sigma), and a density of rho = 1.71 +/- 0.08 g cm(-3). This occultation also provides upper limits of 110 and 15 (3sigma) nanobar for an atmosphere around Charon, assuming respectively a pure nitrogen or pure methane atmosphere.

Transient dwarfism and hypogonadism in mice lacking Otx1 reveal prepubescent stage-specific control of pituitary levels of GH, FSH and LH

Genetic and molecular approaches have enabled the identification of regulatory genes critically involved in determining cell types in the pituitary gland and/or in the hypothalamus. Here we report that Otx1, a homeobox-containing gene of the Otx gene family, is postnatally transcribed and translated in the pituitary gland. Cell culture experiments indicate that Otx1 may activate transcription of the growth hormone (GH), follicle-stimulating hormone (betaFSH), luteinizing hormone (betaLH) and alpha-glycoprotein subunit (alphaGSU) genes. Analysis of Otx1 null mice indicates that, at the prepubescent stage, they exhibit transient dwarfism and hypogonadism due to low levels of pituitary GH, FSH and LH hormones which, in turn, dramatically affect downstream molecular and organ targets. Nevertheless, Otx1−/− mice gradually recover from most of these abnormalities, showing normal levels of pituitary hormones with restored growth and gonadal function at 4 months of age. Expression patterns of related hypothalamic and pituitary cell type restricted genes, growth hormone releasing hormone (GRH), gonadotropin releasing hormone (GnRH) and their pituitary receptors (GRHR and GnRHR) suggest that, in Otx1−/− mice, hypothalamic and pituitary cells of the somatotropic and gonadotropic lineages appear unaltered and that the ability to synthesize GH, FSH and LH, rather than the number of cells producing these hormones, is affected. Our data indicate that Otx1 is a new pituitary transcription factor involved at the prepubescent stage in the control of GH, FSH and LH hormone levels and suggest that a complex regulatory mechanism might exist to control the physiological need for pituitary hormones at specific postnatal stages.

Binding of germ cells to mutant Sld Sertoli cells is defective and is rescued by expression of the transmembrane form of the c-kit ligand

Mutations in the steel (Sl) locus, encoding the c-kit ligand (KL), are associated with impaired germ cell development in mice. Two forms of KL exist: one more steadily associated with the plasma membrane and one more easily released as a soluble protein. We report here that the expression of the two mRNAs coding for the two different form of KL is developmentally regulated in mouse testis. At birth the two mRNAs are expressed at an equal ratio. Starting after 6 days of life, and in parallel to initiation of germ cell differentiation, the mRNA encoding the membrane-associated form of KL becomes more abundant. Germ cells, and especially spermatogonia, express c-kit; thus membrane-bound KL could mediate adhesion between Sertoli cells and germ cells. We find, in fact, that Sertoli cells from Sl/Sld mutant mice, which do not express the mRNA for the membrane-associated form of KL, are unable to bind germ cells. Introduction of a plasmid expressing the transmembrane form, but not the soluble form, of KL restores the ability of Sertoli cells from Sl/Sld mutant mice to bind germ cells. These data suggest that preferential expression of the membrane-anchored form of KL in Sertoli cells may have a role in mediating adhesion of c-kit-expressing germ cells to Sertoli cells.

Inhibition of salivary enzymes by cigarette smoke and the protective role of glutathione

Tobacco smoke is involved in the pathogenesis of several diseases regarding different body systems, mainly cardiovascular and respiratory in addition to its local toxic effect in the oral cavity. The noxious effects of smoke compounds justify the high incidence of periodontal diseases, caries, and neoplastic diseases of oral tissues in smokers. Some toxic components of tobacco smoke, unsaturated and saturated aldehydes, could interact with thiol rich compounds, leading to structural and functional modification of these molecules. Previous papers have demonstrated an in vitro significant decrease of some enzymatic activities, both in plasma and in saliva, following external addition of aldehydes or exposure to cigarette smoke (CS). Furthermore, the same studies underlined the protective effect exerted by the addition of glutathione (GSH) against the damaging role of smoke aldehydes. In this study some salivary enzymes (lactic dehydrogenase [LDH], aspartate aminotransferase [AST] and amylase), and total GSH were measured in 20 volunteers smokers, before and just after smoking a single cigarette. All enzymatic activities showed a significant inhibition following a single cigarette, probably due to the interaction between smoke aldehydes and -SH groups of the enzyme molecules. Moreover, the percentage of the enzymatic inhibition showed a negative correlation with the basal level of salivary GSH. Our results emphasize that not only one cigarette is sufficient to impair the salivary enzymatic activities but also strengthen the proposed protective role of GSH against the noxious biochemical effects of CS.

Development of animal models for adeno-associated virus site-specific integration

The adeno-associated virus (AAV) is unique in its ability to target viral DNA integration to a defined region of human chromosome 19 (AAVS1). Since AAVS1 sequences are not conserved in a rodent's genome, no animal model is currently available to study AAV-mediated site-specific integration. We describe here the generation of transgenic rats and mice that carry the AAVS1 3.5-kb DNA fragment. To test the response of the transgenic animals to Rep-mediated targeting, primary cultures of mouse fibroblasts, rat hepatocytes, and fibroblasts were infected with wild-type wt AAV. PCR amplification of the inverted terminal repeat (ITR)-AAVS1 junction revealed that the AAV genome integrated into the AAVS1 site in fibroblasts and hepatocytes. Integration in rat fibroblasts was also observed upon transfection of a plasmid containing the rep gene under the control of the p5 and p19 promoters and a dicistronic cassette carrying the green fluorescent protein (GFP) and neomycin (neo) resistance gene between the ITRs of AAV. The localization of the GFP-Neo sequence in the AAVS1 region was determined by Southern blot and FISH analysis. Lastly, AAV genomic DNA integration into the AAVS1 site in vivo was assessed by virus injection into the quadriceps muscle of transgenic rats and mice. Rep-mediated targeting to the AAVS1 site was detected in several injected animals. These results indicate that the transgenic lines are proficient for Rep-mediated targeting. These animals should allow further characterization of the molecular aspects of site-specific integration and testing of the efficacy of targeted integration of AAV recombinant vectors designed for human gene therapy.

Identification of a novel type 1 diabetes-specific epitope by screening phage libraries with sera from pre-diabetic patients

We used random peptide libraries displayed on phage to search for ligands to insulin dependent diabetes mellitus-related antibodies and were able to identify several candidate disease-related peptides. One of them, clone 92, showed a significant difference in the frequency of reactivity with the sera of patients and normal controls. Human immunoglobulins immunopurified on phage 92 specifically stained the islets on human pancreatic sections. When injected into rabbits, the selected peptide elicited antibodies that also stained human and rat pancreatic sections, with a pattern similar to that observed with immunoglobulins purified from the sera of patients. No reactivity was observed in other tissues. Our results indicate that the peptide identified in this work mimics a novel, diabetes-related self-antigen.

Leptin receptor-mediated regulation of cholinergic neurotransmitter phenotype in cells of central nervous system origin

Leptin is an adipocyte-secreted hormone that regulates body weight and exerts effects on hematopoiesis, reproduction, and immunity. The leptin receptor (OBR) shares sequence similarity and signaling capabilities with receptors for cytokines of the ciliary neurotrophic factor (CNTF) family. Our previous finding that CNTF and leptin exert similar anti-obesity effects and activate common neuronal signaling pathways, prompted us to investigate whether leptin may share with CNTF the ability to regulate the expression of specific neuronal genes. To this end, we established a cell line, derived from the murine septal cholinergic neuronal cell line SN-56, which stably expresses OBR. In this cell line, termed SN-56/OBR, leptin induces STAT transcription factor activation and STAT-dependent reporter gene expression in a manner similar to that of CNTF. Furthermore, in SN-56/OBR cells both CNTF and leptin produce changes in neurotransmitter and neuropeptide phenotype characteristic of cholinergic neurons, such as an increase in choline acetyltransferase and vasoactive intestinal polypeptide, and a decrease in neuropeptide Y expression. SN-56/OBR cells thus constitute an interesting new model system to investigate leptin action in cells of central nervous system origin. Possible physiological implications of OBR's intrinsic ability to regulate cholinergic phenotypic markers are discussed.

Survivin and Cyclooxygenase-2 are co-expressed in human and mouse colon carcinoma and in terminally differentiated colonocytes

In the evolution of colon rectal cancer (CRC) the imbalance between cell proliferation and apoptosis is considered one of the prominent causes of tumor induction and/or progression. In order to establish the role of anti apoptotic proteins in colon cancer development, we studied with immunohistochemical techniques the expression of Survivin in a mouse model of colon carcinogenesis induced by 1,2-dimethyl-hydrazine treatment. In this mouse model Survivin was over-expressed during tumor development, showing a distribution mimicking that described in the correspondent human malignancies. We also correlated Survivin distribution with COX-2 and beta-Catenin expression patterns. The co-localization of COX-2/beta-Catenin/Survivin in the same epithelial cells in tumor samples lends credence to possible in vivo regulatory effects of COX-2 and beta-Catenin on the intracellular Survivin levels in mouse and human colon cancer.

Image compression through embedded multiwavelet transform coding

In this paper, multiwavelets are considered in the context of image compression and two orthonormal multiwavelet bases are experimented, each used in connection with its proper prefilter. For evaluating the effectiveness of multiwavelet transform for coding images at low bit-rates, an efficient embedded coding of multiwavelet coefficients has been realized. The performance of this multiwavelet-based coder is compared with the results obtained for scalar wavelets.