Expression and functional analysis of fibulin-1 (Fbln1) during normal and abnormal placental development of the mouse.

The extracellular matrix protein fibulin-1 (FBLN1) is an important component of blood vessel walls, as shown by the lethality of mice with homozygous targeted deletion of the Fbln1 gene. Here, we show that a murine placental overgrowth phenotype is associated with elevated Fbln1 transcript levels, suggesting that the gene and its product have a functional role in placentation. Fbln1 exhibits a specific expression pattern in the mouse placenta. Transcripts could not be detected prior to day 12. In subsequent stages, Fbln1 was expressed strongly in the spongiotrophoblast. Other sites of expression were endothelia of large fetal blood vessels, a tissue type reported to not express this gene. In addition, a subset of giant cells expressed the gene. This giant cell specific expression was strongly increased in hyperplastic placentas. Analysis of the placentation in fibulin null mice did not show any abnormality. Attempts to rescue the placental phenotypes of a congenic model of interspecies hybrid placental dysplasia (IHPD) by normalizing expression of Fbln1 proved that Fbln1 alone is not the key cause of phenotypes in these models of placental hyperplasia.

Fibulin-5 deposition in human skin: decrease with ageing and ultraviolet B exposure and increase in solar elastosis.

BACKGROUND: Fibulin-5 was recently found as a secreted extracellular matrix protein that functions as a scaffold for elastic fibres. However, the distribution of fibulin-5 in human skin and its changes during the ageing process are not known. OBJECTIVES: To explore the involvement of fibulin-5 in skin ageing, the age-dependent changes in fibulin-5 localization in human skin were examined compared with those of other elastic fibre components including elastin, fibrillin-1 and fibulin-2. Methods The distribution of elastin, fibrillin-1, fibrillin-2, fibulin-2 and fibulin-5 was investigated by means of immunohistochemistry using their specific antibodies. Skin samples were recovered from 12 healthy subjects undergoing plastic surgery. Ultraviolet (UV) B-irradiated or control nonirradiated buttock skin samples were obtained from two healthy volunteers at 2 days after the irradiation at 2 minimal erythemal doses. RESULTS: In the reticular dermis of young sun-protected skin from the upper arm, fibulin-5 colocalized with the other elastic fibre components, while in the papillary dermis fibulin-5 showed candelabra-like structures perpendicular to the epidermis with an unstained area just beneath the epidermis, which was similar to that of elastin but not fibrillin-1. Fibulin-5 in the reticular dermis decreased and disappeared with age even in sun-protected skin from the thigh, abdomen and upper arm. In sun-exposed skin, fibulin-5 was extremely reduced in the dermis of cheek skin even from a 20-year-old man. UVB irradiation reduced fibulin-5, fibulin-2 and elastin markedly, moderately and weakly, respectively, compared with levels in control nontreated skin. Interestingly, the deposition of fibulin-5 was increased in solar elastosis, like that of other elastic fibre components. CONCLUSIONS: These results suggest that fibulin-5 is a good marker of skin ageing and that the earlier loss of fibulin-5 may involve age-dependent changes in other elastic fibre components.

Early hepatic changes in rats induced by permethrin in comparison with DDT.

In this study permethrin [(3-phenoxyphenyl)-methyl-3-(2,2-dichloroethenyl)-2,2-dim ethylcyclopropanecarboxylate] and DDT [1,1-(2,2,2 trichloroethylidene)-bis-(4-chlorobenzene)] were compared in rats for their effects on early hepatic changes, proposed in the literature to be useful endpoints in screening for non-genotoxic hepatocarcinogenesis and/or liver tumour promotion. We compared the effects of both insecticides on the following endpoints: hepatomegaly, mitogenesis (DNA synthesis, mitotic activity, percentage of binuclear cells) and liver pathology. Male Wistar rats received permethrin (PERM) or DDT in one, three, five and 14 daily oral doses (at 24-h intervals) equivalent to 1/10 LD50. Distinct differences in early liver response between PERM and DDT were observed. DDT stimulated the early effect consisting of hepatomegaly accompanied by an increase in hepatocellular proliferation with signs of cell necrosis. Thus, it might be concluded, that the mitogenic effect of DDT was at least partly related to a regenerative liver response. Although PERM significantly affected DNA synthesis and increased binuclear hepatocytes, this compound did not increase the number of mitotic figures. These results suggest that PERM may inhibit of phase G2 in the cell cycle and consequently it may suppress the cell entering into the stage of mitosis (M-phase). In addition, the present findings provide evidence for the occurrence of abnormal mitoses in the hepatocytes of rats treated with DDT.

[Molecular mechanisms of chemically induced carcinogenesis]. / Molekularne mechanizmy chemicznej kancerogenezy.

In this review recent point of view concerning the molecular mechanisms of chemically induced carcinogenesis is presented. The new and promising trends of neoplasia investigations are based on discovery of protooncogenes and tumor suppressor genes, which maintain tissue homeostasis by controlling cellular proliferation and differentiation. It is generally recognised, that mutations induced by genotoxic carcinogens, particularly those resulting in activation of protooncogenes and inactivation of suppressor genes, play a crucial role in the initiation step of multistage process of tumorigenesis. Tumor promotion is recognized as a process whereby initiated cells are stimulated to selective growth and then, to develop into the cancer during progression step. Tumor promotion can be affected by many nongenotoxic carcinogens. In this review the attention is given to the mutational activation of the c-ras oncogenes and inactivation of p53 suppressor gene in rodent and human cancers by genotoxic carcinogens. Moreover, the significance of nongenotoxic carcinogens and the mechanisms by which these compounds may accelerate tumorigenesis are discussed.

[The role of cell proliferation in carcinogenesis]. / Rola proliferacji komórkowej w kancerogenezie.

Cell proliferation is regulated by the cell cycle which is controlled by a number of cyclin-dependent kinases (CDKs). The functions of CDKs are critical for cell cycle and are required to traverse checkpoints. A network of inhibitors (CKI) of the cyclin-dependent kinases provide the important function of regulating the activity of the cyclin complexes. Deregulation of these results in either uncontrolled proliferation or cell death (apoptosis). Cell proliferation is an important factor in the development of carcinogenesis induced by genotoxic as well as nongenotoxic carcinogens. It is an integral part of the process of converting DNA adducts to mutations, it also decreases the time that is available for DNA repair and is required to clonal expansion of initiated cell populations. Moreover, cell proliferation increases the number of initiated cells by blocking cell death (apoptosis) and pertrubing checkpoints in the cell cycle. Two major mechanisms of induction of cell proliferation (regenerative and mitogens-stimulated) were discussed in relation to their potential roles in the carcinogenicity.

[The role of apoptosis in cell physiology and pathology]. / Rola apoptozy w fizjologii i patologii komórki.

The cell death is a natural physiological process that occurs in every living organism. It is clear that programmed cell death--apoptosis--is an important mechanism maintaining cell number in a multicellular organism. This review summarises recent progress in the field of apoptosis. Extracellular signals, such as various growth factors and antigen Fas ligand can trigger apoptosis via cell surface receptors. Within the cell the tumor suppressor gene p53 and oncogenes c-myc, c-fos and c-jun tend to activate apoptosis, while other genes such as most members of the bcl-2 family, tend to suppress it. Many of these signals regulate a family of cysteine proteases--related to interleukin 1 beta converting enzyme (ICE)--caspases--which play a crucial role in apoptosis. Many factors that affect apoptosis also affect the cell cycle. For example, p53 appears to be an important mediator of both apoptosis and cycle arrest. If DNA damage is repaired during cycle arrest, the cell survives. Special attention is paid to the abnormalities in the regulation of apoptosis that may contribute to different pathogenic processes.

Sequence and expression of a novel member (LTBP-4) of the family of latent transforming growth factor-beta binding proteins.

Overlapping cDNA clones from human heart and melanoma libraries were used to establish the 1587-residue sequence of a novel protein (LTBP-4) belonging to the family of extracellular microfibrillar proteins which also bind transforming growth factor-beta. LTBP-4 consists of 20 EG modules, 17 of them with a consensus sequence for calcium binding, 4 TB modules with 8 cysteines and several proline-rich regions. Northern blots demonstrated a single 5 kb mRNA which is highly expressed in heart but also present in skeletal muscle, pancreas, placenta and lung. The modular structure predicts that LTBP-4 should be a microfibrillar protein which probably also binds TGF-beta.

Early hepatic changes induced in rats by two hepatocarcinogenic organohalogen pesticides: bromopropylate and DDT.

The aim of the present studies was to describe the effect of two organohalogen pesticides: DDT and bromopropylate, on early changes in rat liver, proposed in the literature to be useful endpoints in screening of non-genotoxic hepatocarcinogens and/or liver tumor promoters. We investigated the effects on the following endpoints: hepatomegaly, mitogenesis (DNA synthesis, mitotic activity, percentage of binuclear cells) and cytochrome CYP2B1-dependent monooxygenase induction. The histological and cytochemical changes in the liver were also recorded. Male Wistar rats received bromopropylate in one, three or five daily oral doses of 125, 250, and 500 mg/kg body wt. day-1. DDT was applied as one, three, and five daily oral doses of 24 mg/kg body wt. day-1 (this dose is close to the mean hepatocarcinogenic dose in male Wistar rats: 34.1 mg/kg body wt. day-1). In the case of both pesticides the early effects observed consisted of hepatomegaly accompanied by an increase in the p-nitroanisole O-demethylase activity and hepatocyte proliferation. Hepatocyte proliferation was elevated during the total experimental period. Vacuolated cytoplasm and evident focal necrosis may suggest that the maximal increase in hepatocyte proliferation, preceding hepatomegaly, is at least partly related to a regenerative liver response to pesticides. In addition to the above-mentioned early changes, the present findings provide new evidence for the occurrence of dose-dependent abnormal mitoses (and c-mitoses) in the hepatocytes of the bromopropylate and DDT treated rats.

[The effect of selected polychlorinated hydrocarbon pesticides on proliferation of cells in rat liver (14 day experiment)]. / Wplyw wybranych pestycydów z grupy polichlorowanych weglowodorów na proliferacje komórkowa w watrobie szczurów (doswiadczenie 14 dniowe).

The aim of present studies was to describe the effect of two organochlorine pesticides: nuarimol and DDT on the changes in rat liver, proposed in the literature to be useful endpoints in screening of non-genotoxic hepatocarcinogens and/or liver tumor promoters. The effects on the following endpoints: mitogenesis (DNA synthesis and mitotic activity), hepatomegaly as well as histological changes in rat liver have been investigated. Male Wistar rats received nuarimol or DDT in one, five and fourteen daily oral administration of the doses of 125 and 12 mg/kg b.w. day-1 respectively. In the case of both pesticides the effects observed consisted of hepatomegaly and hepatocyte proliferation (DNA synthesis and mitotic activity), although our studies indicated several distinct differences in the hepatic response between nuarimol, on the one hand and DDT on the other. The differences were reflected in the character and the basal rate of hepatocyte proliferation. Nuarimol elicited rapid but transient wave of hepatocyte proliferation during the first day of exposure. As opposite to nuarimol, DDT induced sustained hepatocyte proliferation during experimental period (14 days). Moreover, DDT induced evident focal necrosis and abnormal mitoses whereas nuarimol caused only slight vacuolated cytoplasm. Thus it can be concluded that nuarimol induced in rat liver direct mitogenic effect. On the other hand, DDT which is well known hepatocarcinogen, was found to produce mitogenic effect appearing to be related to regenerative response, since histological signs of necrosis were apparent.

Dynamin binds to SH3 domains of phospholipase C gamma and GRB-2.

Src homology 3 (SH3) domains are found in a variety of proteins that are involved in signal transduction or represent components of the cytoskeleton. These domains are thought to serve as modules that mediate specific protein-protein interactions that include proline-rich sequences on the target protein. We have identified proteins of 110, 80, 65, and 43 kDa in human embryonic fibroblasts that bind specifically to the SH3 domain of phospholipase C gamma, a primary substrate of receptor tyrosine kinases, and characterized the 110-kDa band as the microtubule-activated GTPase dynamin. In addition, dynamin binds the son of sevenless adaptor protein GRB-2 with even higher affinity. This interaction does not require the dynamin GTPase function and involves a proline-rich target sequence between residues 812 and 820 of dynamin.

Modulation of p145c-kit function in cells of patients with acute myeloblastic leukemia.

The function of the steel factor receptor, p145c-kit, in patient-derived acute myeloblastic leukemia (AML) cells was investigated. Steel factor stimulation of AML cells coexpressing p145c-kit and the progenitor cell antigen CD34 resulted in complete receptor down-regulation, a marked decrease of CD34 antigen expression, and the induction of the granulocyte lineage antigen CD15. These changes in surface marker expression paralleled morphological differentiation to granulated blasts and promyelocytes. Interestingly, the same phenotype was achieved by IL-3 stimulation of AML cells. p145c-kit extracellular domain-specific antibodies had either blocking or enhancing effects on ligand binding, receptor phosphorylation and down-regulation, and induction of cell proliferation. Correlations of these phenomena with distinct effects of antibody stimulation on cell substrate phosphorylation provide clues for the dissection of the p145c-kit signal and the analysis of its relevance for AML.

[Toxicity of aldehydes used as disinfectants]. / Toksycznosc aldehydów stosowanych jako srodki dezynfekcyjne.

The paper presents a review of current scientific literature on the toxicology of aldehydes used as cold disinfectants. A particular attention was paid towards the mutagenic, teratogenic and cancerogenic potential as well as occupational hazard and risk for patients exposed to aldehydes.

Characterization of hemopoietic cell populations from human cord blood expressing c-kit.

Human cord blood or bone marrow cells expressing the CD34 surface antigen include a population of pluripotent progenitors. We identified and isolated a subpopulation of cells coexpressing CD34 and c-kit, a transmembrane receptor with tyrosine kinase activity. Novel monoclonal antibodies (16A6, 14A3, 3D6) directed against the extracellular domain of c-kit were used for immunofluorescence labeling and sorting of low-density mononuclear cells (MNCs) from umbilical cord blood and bone marrow. The frequency of c-kit-labeled MNCs from cord blood (mean 5.0% +/- 2.1%, n = 16) was similar to that from adult bone marrow (mean 3.7% +/- 1.3%, n = 4). On average, 1.4% of CD34-positive cells were recorded in cord blood and 2.1% in bone marrow MNCs. Roughly 60% of CD34-positive cells coexpressed c-kit. The ability of CD34+/c-kit+ cells to form multilineage colonies (CFU-GEMM) was assayed after sorting with an antibody that did not show any significant effect on c-kit ligand (RL) or granulocyte/macrophage colony-stimulating factor (GM-CSF)-induced colony formation. For CD34+/c-kit+ cells, we found a 20- to 50-fold enrichment as against total MNCs, and a 2-fold enrichment if compared with the CD34+/c-kit-population. To study expression of c-kit in lymphocytic precursors, monoclonal anti-CD7 or anti-CD10 antibodies were used simultaneously. In contrast to CD34-expressing cells, however, no consistent double-labeled subpopulation of lymphocytic cells was detected. Furthermore, coexpression of CD38 (73% +/- 14%, n = 4) or CD33 (29% +/- 12%, n = 5) on a majority of c-kit-positive cells showed their lineage commitment to erythropoiesis and granulocytopoiesis.

Differential effects of carboxy-terminal sequence deletions on platelet-derived growth factor receptor signaling activities and interactions with cellular substrates.

Chimeric receptors composed of the human epidermal growth factor receptor (EGF-R) extracellular domain fused to wild-type and truncated platelet-derived growth factor receptor (PDGF-R) intracellular sequences were stably expressed in NIH 3T3 cells devoid of endogenous EGF-Rs. This experimental system allowed us to investigate the biological activity of PDGF-R cytoplasmic-domain mutants in PDGF-R-responsive NIH 3T3 cells by activating PDGF-specific signaling pathways with EGF. Deletion of 74 carboxy-terminal amino acids severely impaired the ability of the PDGF-R cytoplasmic domain to associate with cellular substrates in vitro. This deletion also inhibited receptor and substrate phosphorylation, reduced the receptor's mitogenic activity, and completely abolished its oncogenic signaling potential. Surprisingly, removal of only six additional amino acids, including Tyr-989, restored substantial receptor and substrate phosphorylation capacity as well as transforming potential and yielded a receptor with wild-type levels of ligand-induced mitogenic activity. However, the ability of this chimera to bind phospholipase C gamma was severely impaired in comparison with the ability of the wild-type receptor, while the association with other cellular proteins was not affected. Further deletion of 35 residues, including Tyr-977, nearly abolished all PDGF-R cytoplasmic-domain biological signaling activities. None of the three C-terminal truncations completely abolished the mitogenic potential of the receptors or had any influence on ligand binding or receptor down regulation. Together, these data implicate the 80 C-terminal-most residues of the PDGF-R, and possibly Tyr-989, in phospholipase C gamma binding, while receptor sequences upstream from Asp-988 appear to be essential for specific interactions with other cellular polypeptides such as ras GTPase-activating protein and phosphatidylinositol 3-kinase. Thus, the mutants described here allow the separation of distinct PDGF-activated signaling pathways and demonstrate that phospholipase C gamma phosphorylation is not required for mitogenesis and transformation.

Characterization and partial purification of a high-molecular-mass, calmodulin-binding, tyrosyl-phosphorylated protein from lymphocyte plasma membranes.

A plasma membrane phosphoprotein with a species-dependent molecular mass of 108 or 112 kDa (P108/112) was analyzed in lymphoid cells from rats and humans. After 24 h lectin stimulation its in vitro phosphorylation was raised to an important extent. Phosphotyrosine was analyzed by 2-D electrophoresis. Calmodulin was bound by P108/112 in a Ca2+-dependent manner. P108/112 remained insoluble after extraction with detergent, high salt, EDTA, or high pH. After chlorethanol extraction it was partially purified by gel filtration. P108/112 shows conspicuous similarities with the 110-kDa protein from chicken intestine microvilli.

Ultraviolet light-induced crosslinking of two major phosphoproteins and poly(A)+RNA from free polyribosomes; changes in phosphorylation by inhibitors of transcription and translation.

Polyribosomes were isolated without the use of detergents, irradiated with ultraviolet light and labelled in the presence of (gamma-32P) adenosine 5'-triphosphate. Poly(A)+RNA-protein structures separated by chromatography on oligo (dT)-cellulose contained up to 1o crosslinked proteins as shown by SDS-polyacrylamide gel electrophoresis. These included a 71 kDa poly(A)-bound species and two major phosphoproteins of 66 and 13o kDa. Pretreatment of rats with inhibitors of transcription and translation caused different and significant alterations in the labelling of the two phosphoproteins, suggesting that phosphorylation of proteins closely associated with mRNA may be involved in the regulation of the stability of this RNA or its binding to structural elements in the cell.

Phosphoproteins crosslinked to poly(A) + heterogeneous nuclear RNA after irradiation with ultraviolet light.

Isolated liver nuclei or whole lymph node lymphocytes stimulated with concanavalin A in culture were irradiated with ultraviolet light. The crosslinked structures of poly(A)+ heterogeneous nuclear RNA and protein were purified on oligo(dT)-cellulose after labelling irradiated nuclei in the presence of adenosine 5'-[gamma-32P]triphosphate and analysed by SDS-polyacrylamide gel electrophoresis. The liver and lymphocyte nuclear proteins included about 17-19 species of 35-150 kDa and were shown to produce quite similar electrophoretic band patterns. Two proteins of 110-120 and 40-42 kDa were phosphorylated. Using partial proteolytic digestion the large-size crosslinked phosphoprotein has been identified as the 110 kDa component described previously (Schweiger, A. and Kostka, G. (1984) Biochim. Biophys. Acta 782, 262-268). The 40-42 kDa band was presumably related to the group C species of main proteins associated with heterogeneous nuclear RNA. In crosslinked nuclear structures from rats treated with low doses of alpha-amanitin for 1 h the relative amount of the 110-120 kDa phosphoprotein was reduced while the labelling with [32P]ATP was almost abolished.

Biphasic increase in the in vivo phosphorylation of nuclear 110-kDa protein during early lymphocyte transformation.

A major 110-kDa phosphoprotein in rat liver and hepatoma (P 110) was identified in nuclear 0.2 M HCl extracts from rat lymph node cells. Stimulation with concanavalin A altered both the amount of P110 and, more strikingly, its in vivo phosphorylation in a typical biphasic manner with an initial maximum after 10-14 h. RNA synthesis showed a similar biphasic increase. Inhibition of hnRNA synthesis (5,6 dichlorobenzimidazoleriboside), but not of DNA synthesis (hydroxyurea), depressed both the amount of P110 and its phosphorylation markedly.

Concentration of particular high molecular mass phosphoproteins in rat liver nuclei and nuclear matrix decreases following inhibition of RNA synthesis by alpha-amanitin.

Purified liver nuclei were isolated from rats treated with non-lethal doses of alpha-amanitin, actinomycin D, galactosamine or cycloheximide. The nuclei were incubated in the presence of adenosine 5'-[gamma-32P]triphosphate, and digested with DNAase or DNAase plus high salt concentrations to prepare nuclear residual structures. Using SDS-polyacrylamide gel electrophoresis followed by autoradiography, samples from untreated rats were shown to contain major phosphoproteins in the range 76-260 kDa, with a prominent triplet of bands with 110, 117 and 128 kDa. Treatment of animals with alpha-amanitin or high doses of actinomycin D and galactosamine caused a significant decrease in the concentration of a few phosphorylated species, including the 110 kDa protein in whole nuclei, and their disappearance from the nuclear matrix or residual ribonucleoprotein structures after 1-3 h. The changes were reversible, complete recovery being observed after 5 h in the case of alpha-amanitin. No similar results were obtained with nuclei from rats treated with the translation inhibitor cycloheximide. The data are discussed in view of a possible effect of certain high molecular mass phosphoproteins on reactions of the heterogeneous nuclear RNA/mRNA pathway in the cell.

Synthesis of 2',5'-oligoadenylate by rat liver nuclear matrix protein.

Nuclear matrix was prepared from unstimulated rat liver by treatment of nuclei with DNAse and 0.4 M NaCl and was further extracted with 2.0 M NaCl. Proteins were bound to poly(rI):(rC)-agarose, incubated with (alpha-32P) adenosine 5'-triphosphate and 2',5'-linked oligoadenylate was isolated from the supernatant. The substance inhibited amino acid incorporation in a reticulocyte translation system and was identified after enzymatic treatment followed by thin-layer chromatography on PEI-cellulose. The possible function of 2',5'-oligo(A) synthetase in the maturation of pre-mRNA associated with nuclear matrix is discussed.