Identification of proteins from a cell wall fraction of the diatom Thalassiosira pseudonana: insights into silica structure formation.

Diatoms are unicellular eucaryotic algae with cell walls containing silica, intricately and ornately structured on the nanometer scale. Overall silica structure is formed by expansion and molding of the membrane-bound silica deposition vesicle. Although molecular details of silica polymerization are being clarified, we have limited insight into molecular components of the silica deposition vesicle, particularly of membrane-associated proteins that may be involved in structure formation.

Accelerated diabetic glomerulopathy in galectin-3/AGE receptor 3 knockout mice.

Several molecules were shown to bind advanced glycation end products (AGEs) in vitro, but it is not known whether they all serve as AGE receptors and which functional role they play in vivo. We investigated the role of galectin-3, a multifunctional lectin with (anti)adhesive and growth-regulating properties, as an AGE receptor and its contribution to the development of diabetic glomerular disease, using a knockout mouse model. Galectin-3 knockout mice obtained by gene ablation and the corresponding wild-type mice were rendered diabetic with streptozotocin and killed 4 months later, together with age-matched nondiabetic controls.

Comparative analysis of galectins in primary tumors and tumor metastasis in human pancreatic cancer.

Galectins are galactoside-binding proteins that exhibit an important function in tumor progression by promoting cancer cell invasion and metastasis formation. Using Northern blotting and Western blotting analysis, in situ hybridization (ISH), and immunohistochemistry (IHC), we studied galectin-1 and galectin-3 in tissue samples of 33 primary pancreatic cancers and in tumor metastases in comparison to 28 normal pancreases. Furthermore, the molecular findings were correlated with the clinical and histopathological parameters of the patients.

Galectin-1 and galectin-3 in chronic pancreatitis.

Galectin-1 and galectin-3 have important functions in cell-cell interactions, cell adhesion to extracellular matrix, the organization of extracellular matrix, and tissue remodeling. To assess their potential role in chronic pancreatitis (CP), we examined their expression by Northern blot analysis, in situ hybridization, immunohistochemistry, and Western blot analysis in normal and CP pancreatic tissues. Northern blot analysis revealed a 4.

Pleckstrin homology domains interact with filamentous actin.

A fraction of Bruton's tyrosine kinase (Btk) co-localizes with actin fibers upon stimulation of mast cells via the high affinity IgE receptor (FcepsilonRI). In this study, a molecular basis of the Btk co-localization with actin fibers is presented. Btk and other Tec family tyrosine kinases have a pleckstrin homology (PH) domain at their N termini.

The role of actin microfilaments in the down-regulation of the degranulation response in RBL-2H3 mast cells.

Cross-linking of FcepsilonRI on rat basophilic leukemia (RBL) cells initiates a signaling cascade leading to degranulation of the cells and the release of inflammatory mediators. Inhibitors that disrupt microfilaments, such as latrunculin and cytochalasin D, do not cause any degranulation on their own, but they do enhance FcepsilonRI-mediated degranulation. Dose-response studies show a good correlation between inhibition of actin polymerization and increased degranulation.

Galectin-3 inhibits granulocyte-macrophage colony-stimulating factor (GM-CSF)-driven rat bone marrow cell proliferation and GM-CSF-induced gene transcription.

The expression of galectin-3 (formerly known as IgE-binding protein or Mac-2) in rat bone marrow (BM) was investigated by FACS, immunocytochemical and immunoblot analysis. The functional significance of rat recombinant galectin-3 on mouse recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF)-driven proliferation of macrophage progenitors and gene transcription was further examined. Immunocytochemical analysis of in situ BM sections demonstrated galectin-3 in myelopoietic cells and surrounding stroma, whereas erythropoietic and lymphopoietic environments essentially lacked galectin-3 expression.

A human lectin, galectin-3 (epsilon bp/Mac-2), stimulates superoxide production by neutrophils.

A family of soluble animal lectins, galectins, with beta-galactoside-binding activity, is gaining increased attention. One member of this family, galectin-3, has been previously designated by this group as epsilon bp, for its IgE-binding activity. On the basis of the saccharide specificity and other biochemical characteristics of epsilon bp, it is possible that this lectin could have an important extracellular modulatory role, functioning through recognition of critical cell surface glycoproteins on many cell types.

An endogenous lectin, galectin-3 (epsilon BP/Mac-2), potentiates IL-1 production by human monocytes.

Galectin-3 is a member of a growing family of beta-galactoside-binding animal lectins and previously designated as epsilon BP (IgE-binding protein) by this laboratory and as Mac-2, CBP35, L-34 and L-29 by other researchers. While possible intracellular functions have been proposed for galectin-3, existing data also suggest an extracellular modulatory role of this lectin. For example, epsilon BP/Mac-2 was found to be secreted by various cells and capable of activating mast cells, possibly through cross-linking of cell surface glycoproteins involved in cell activation.

Activation of rat basophilic leukemia cells by epsilon BP, an IgE-binding endogenous lectin.

IgE-binding protein (epsilon BP) is a beta-galactoside-binding animal lectin identified by its affinity for IgE. We have reported that epsilon BP also binds the mast cell high-affinity IgE receptor (Fc epsilon RI), via lectin-carbohydrate interaction. We have now studied the physiological significance of epsilon BP-IgE-Fc epsilon RI interactions in mast cell activation using rat basophilic leukemia (RBL) cells as the model system.

The adhesive specificity of the soluble human lectin, IgE-binding protein, toward lipid-linked oligosaccharides. Presence of the blood group A, B, B-like, and H monosaccharides confers a binding activity to tetrasaccharide (lacto-N-tetraose and lacto-N-neotetraose) backbones.

The immunoglobulin E-binding protein, epsilon BP (also known as CBP35, Mac-2, L-34, and L-29), is a beta-galactoside-binding protein of approximately 30 kDa and a member of the animal lectin family termed S-type or S-Lac. Multiple biological activities have been attributed to this lectin such as mediation of IgE binding to the surface of Langerhans cells and activation of mast cells through binding to the high affinity IgE receptor. In order to better understand the cell-binding activity and the proposed role for epsilon BP as a biological response modifier, we have studied the specificity of binding of the radioiodinated epsilon BP to a series of lipid-linked, structurally defined oligosaccharide sequences of the lacto/neolacto family.

Obesity, diabetes, and neoplasia in yellow A(vy)/- mice: ectopic expression of the agouti gene.

The viable yellow A(vy) mutation results in a mottled yellow mouse that is obese, slightly larger than its nonyellow sibs, and more susceptible to tumor formation in those tissues sensitized by the strain genome. The mutation exhibits variable expressivity resulting in a continuum of coat color phenotypes, from clear yellow to pseudoagouti. The mouse agouti protein is a paracrine signaling molecule that induces hair follicle melanocytes to switch from the synthesis of black pigment to yellow pigment.

Expression and function of an IgE-binding animal lectin (epsilon BP) in mast cells.

epsilon BP (IgE-binding protein) is a 31,000 M(r) protein originally identified in rat basophilic leukemia (RBL) cells. The protein is composed of two domains with the amino-terminal domain containing a highly conserved repetitive sequence and the carboxyl-terminal domain containing consensus sequences shared by other beta-galactoside-binding soluble lectins. The protein has wide tissue distribution, is found on cell surfaces and in extracellular milieu.

Epsilon BP, a beta-galactoside-binding animal lectin, recognizes IgE receptor (Fc epsilon RI) and activates mast cells.

IgE-binding protein (epsilon BP) was originally identified in rat basophilic leukemia (RBL) cells by virtue of its affinity for IgE. epsilon BP is now known to be a beta-galactoside-binding lectin containing an S-type carbohydrate recognition domain. It is identical to a macrophage surface antigen, Mac-2, and lectins designated as CBP35, L-34, and RL-29, for which various functions have been suggested.

An intestinal galactose-specific lectin mediates the binding of murine IgE to mouse intestinal epithelial cells.

A number of lactose-binding lectins have recently been identified in the rat and mouse intestine, one of which corresponds to the C-terminal domain of IgE-binding proteins, originally identified in rat basophilic leukemia (RBL) cells and mouse 3T3 fibroblasts. In the present report, we describe the affinity purification of a rat intestinal lactose-specific lectin which binds murine IgE antibodies. This binding most likely occurs via the immunoglobulin carbohydrate chains, as it is inhibited by lactose.

Surface expression of functional IgE binding protein, an endogenous lectin, on mast cells and macrophages.

IgE-binding protein (epsilon BP) is a galactoside-specific lectin containing an S-type carbohydrate-recognition domain. It was originally identified in rat basophilic leukemia cells and is now known to be identical to a macrophage surface Ag, Mac-2, and lectins designated as CBP 35/L-34/RL-29. It has also been related to a nonintegrin laminin-binding protein isolated from mouse macrophages.

Expression of biologically active recombinant rat IgE-binding protein in Escherichia coli.

IgE-binding protein (epsilon BP) is a protein which has affinity for IgE and was originally identified in rat basophilic leukemia (RBL) cells. Subsequently, it was found to be the rat homolog of CBP35, a murine beta-galactoside-specific lectin. This protein is also designated as L-34 and RL-29 and studied independently by several laboratories.

Diabetogenic response to streptozotocin varies among obese yellow and among lean agouti (BALB/c x VY)F1 hybrid mice.

To test the hypothesis that the elevated insulin levels in obese neoplasia-susceptible yellow Avy/- mice might be a major factor stimulating tumor formation, it is necessary to use normoinsulinemic yellow mice. Although our attempt to obtain normoinsulinemic, euglycemic mice by streptozotocin treatment was unsuccessful, we did observe significant differences in the responsiveness to this treatment among mice of identical genotype. These differences were observed among female yellow Avy/A and agouti A/a (BALB/c x VY)F1 hybrid mice in the responses of body weight gain, plasma glucose, and plasma insulin levels to a single intraperitoneal injection of either 150 or 200 mg/kg streptozotocin (STZ) at 4 weeks of age followed by a 22-week observation period.

Amino-terminal peptide of growth hormone enhances insulin action in normal rats.

Earlier studies demonstrated that the 20K-dalton variant of human GH (hGH), which differs from hGH by deletion of the amino acid residues 32-46, has decreased insulin-like activity. The current study assessed whether a peptide representing this deleted region could enhance insulin-stimulated glucose uptake in the intact rat and if this effect was localized in liver and/or muscle. Peptides hGH-(32-46) and rat GH-(32-45) were used in these studies.

Increased sensitivity of adipose tissue to insulin after in vivo treatment of yellow Avy/A obese mice with amino-terminal peptides of human growth hormone.

Treatment of obese yellow Avy/A mice with the human GH (hGH) peptide hGH-(1-43) enhanced the in vitro sensitivity of their adipose tissue to insulin. Insulin-stimulated glucose oxidation, as determined by measurement of 14CO2 production, was enhanced 106% after administration of hGH-(1-43) at a dosage of 1 microgram/day for 3 days. A significant increase in CO2 production was detected with as little as 100 ng peptide/day for 3 days.

Comparison of the acute metabolic effects of 22,000-dalton and 20,000-dalton growth hormone in human subjects.

The acute metabolic effects of 20,000-dalton human growth hormone (hGH20K) in man have not previously been tested. We compared changes in concentrations of free fatty acids (FFA), glucose, and insulin in nine growth hormone deficient children following injection of 22,000-dalton intact human growth hormone (hGH22K) and the smaller variant, hGH20K. There was a significant decline (37%) in the mean FFA concentration from baseline to 1/2 hour post-injection and from baseline to 1 hour post-injection (36%) in the children given hGH22K, but no such decline was seen after injection of hGH20K.

Differential responses of yellow Avy/A and agouti A/a (BALB/c X VY) F1 hybrid mice to the same diets: glucose tolerance, weight gain, and adipocyte cellularity.

Differences in weight gain, efficiency of food utilization, glucose tolerance, insulin levels, and adipocyte cellularity were measured when three different diets were fed to lean agouti and obese yellow mice. Sets of adult and weanling agouti (A/a) and yellow (Avy/A) (BALB/c X VY) F1 hybrid mice were fed high-sucrose (HS), 10 percent fat, or regular lab chow (control). Some mice received the diets only after 12 weeks of eating lab chow (adult-fed); others ate the diets from the time of weaning.

In vitro insulin-like actions of human growth hormone: a study with an insulin antibody.

When polyclonal insulin antibodies were preincubated with either adipose tissue from hypophysectomized rats or adipocytes from normal rats, human growth hormone failed to stimulate glucose oxidation. Removal of insulin from adipocytes through incubation with pyruvate at pH 7.0, followed by washing three times, also abolished subsequent in vitro insulin-like action of hGH.

Glycosylation abolishes an in vitro insulin-like action of prolactin.

Ovine prolactin stimulated 14C-CO2 production from labeled glucose in adipose tissue of hypophysectomized rats in vitro, an insulin-like activity. Glycosylation of the hormone by attachment of a carbohydrate unit at asparagine31 abolished this in vitro insulin-like action. However, neither nonglycosylated nor glycosylated prolactin exhibited in vivo insulin-like action, as they did not lower serum glucose or non-esterified fatty acids in fasted hypophysectomized rats.

Impairment of glucose tolerance in yellow (Avy/A) (BALB/c X VY) F-1 hybrid mice by hyperglycemic peptide(s) from human pituitary glands.

A fraction of human pituitary extract containing low molecular weight peptide(s) was found to impair glucose tolerance in obese yellow (Avy/A) (BALB/c X VY) F-1 hybrid female mice. In these mice, purified human GH was not hyperglycemic. Glucose tolerance of untreated yellow mice was somewhat less impaired than that of untreated ob/ob mice, and priming with dexamethasone was not required to elicit impairment of glucose tolerance.