Haptoglobin in Carnivora: a unique molecular structure in bear, cat and dog haptoglobins

Haptoglobin (Hp), a hemoglobin-binding protein in plasma, consists of alpha and beta subunits and has a tetra-chain arrangement (beta-alpha-alpha-beta) connected by disulfide bridges in most mammals so far examined. Dog Hp has been reported to be unique compared with other Hps in respect that (1) the two alpha beta units are joined by a non-covalent interaction rather than a disulfide bridge and (2) the alpha chain has an oligosaccharide-binding sequence (Asn-X-Ser/Thr) and is glycosylated. To determine whether the unique structures of dog Hp are common in the Carnivora, we purified Hps from sera of bear and cat, and analyzed their subunit structure and partial amino acid sequences. The analyses by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, under both reducing and non-reducing conditions, revealed that bear and cat Hps have similar subunit arrangements to dog Hp, suggesting the absence of a disulfide bridge between two alpha chains. This was confirmed by amino acid sequence analysis of the alpha chains: that is, Cys15 participating in the inter-alpha chain disulfide bridge was replaced by Val in bear or Leu in cat and dog. Thus, the unique subunit arrangement of Hp reported in dog may be common in the Carnivora. In contrast to dog Hp, however, alpha chains of bear and cat Hps were found not to have the typical oligosaccharide binding sequence on their alpha chains and were not glycosylated.

Polyacrylamide gel electrophoretic patterns of chicken serum in acute inflammation induced by intramuscular injection of turpentine

To develop a method to detect hidden inflammation using serum protein in chickens, changes in serum proteins with acute inflammation were analyzed using a turpentine-induced inflammation model. Inflammation in the pectoral muscle of a 14-wk-old White Leghorn became apparent 3 h after the injection of turpentine and became more severe thereafter. Coincident with the development of inflammation, changes in serum proteins were analyzed by electrophoresis on polyacrylamide gradient gels. The electrophoretic patterns were divided into 21 segments. Two of these segments increased remarkably. These were located near the center of the electrophoretic pattern and were identified as transferrin due to iron staining, correlation of movement against a commercial transferrin sample in SDS-PAGE, and immunoblotting. These results suggest that transferrin may serve as a marker for inflammation in chicken.

Stimulation of haptoglobin synthesis by interleukin-6 and tumor necrosis factor, but not by interleukin-1, in bovine primary cultured hepatocytes

The hepatic synthesis of acute phase proteins in ruminants has been suggested to be regulated by some mechanisms different from those in other species such as rodents and human. To explore possible regulatory factors unique to ruminants, we examined effects of interleukin (IL)-6, IL-1 and tumor necrosis factor (TNF), on haptoglobin (Hp) synthesis using a primary culture system of bovine hepatocytes. After bovine primary cultured hepatocytes were incubated in the presence of various concentrations of the cytokines, the synthesis and mRNA level of haptoglobin and albumin were measured by labeling with [35S]-methionine and immunoprecipitation, and by Northern blot analysis, respectively. Hp synthesis was dose-dependently increased by recombinant human (rh) IL-6, and also by rhTNF-alpha, but to a less extent, while it was not affected by rhIL-1 beta. The stimulatory effect is mainly pretranslational, because mRNA level of Hp changed in parallel with protein synthesis. In contrast, albumin synthesis was suppressed by these three cytokines similarly. These results are inconsistent with the previously proposed view that TNF and IL-1 overlap in their pathways leading to the transcriptional activation of many acute phase protein genes. In conclusion, there is a species-specific unique signaling system, especially for TNF, in transcriptional activation of bovine Hp gene.

Possible involvement of a small G-protein sensitive to exoenzyme C3 of Clostridium botulinum in the regulation of myofilament Ca2+ sensitivity in beta-escin skinned smooth muscle of guinea pig ileum

The effects of exoenzyme C3 of Clostridium botulinum on Ca(2+)- and drug-induced tension developments were investigated in beta-escin skinned smooth muscle of guinea pig ileum to test the involvement of a small G-protein in the regulation of myofilament Ca2+ sensitivity. C3 is known to ADP-ribosylate the rho p21 family of small G-proteins. Treatment with C3 (0.35 microgram/ml, for 30 min) shifted the pCa-tension curve rightward along the Ca2+ concentration axis, indicating a decrease in Ca2+ sensitivity of the contractile elements. The inhibitory effect of C3 was not preserved after treatment with GDP beta S (1 mM), an antagonist of GTP for the binding to G-proteins. Stimulation of muscarinic receptors with carbachol (CCh, 100 microM) shifted the pCa-tension curve leftward, indicating Ca2+ sensitization of tension development. The Ca(2+)-sensitizing effect of CCh was not observed after C3 treatment. When GTP gamma S (10 microM), an activator of G-proteins, was applied at a plateau of tension development produced by a moderate concentration of Ca2+, further increase in tension was elicited and the effect of GTP gamma S was inhibited by C3 treatment. The results suggest the possible involvement of a rho p21-like small G-protein in the regulation of Ca2+ sensitivity of smooth muscle myofilaments.

Orally administered spermine induces precocious intestinal maturation of macromolecular transport and disaccharidase development in suckling rats

The effect of orally administered spermine on intestinal cessation in bovine IgG transport and digestive enzymes in the small intestine was examined in the suckling rats. By the repeated oral administration of spermine (0.1 or 0.25 mumol/g bwt) for 5 days, the ratio of protein to DNA was significantly increased. Maltase and lactase activities changed dose dependently in the spermine treated pups. Absorption of bovine IgG transport in the intestine was dose dependently depressed by spermine treatments. Morphological inspection of treated pups showed a decline in the number of epithelial cells that absorb bovine IgG and in their vesicle sizes from basal to upper regions of the villi. The ratio of mitosis in the crypt of treated pups significantly increased in the small intestine and cecum. These results suggest that exogenously administered spermine induces precocious maturation of the macromolecular transmission and disaccharidase activity in the small intestine of the suckling rats.

Precocious cessation of intestinal macromolecular transport and digestive enzymes development by prostaglandin E2 in suckling rats

The effect of repeated oral administration of prostaglandin analogue (dmPGE2) on intestinal macromolecular transport and digestive enzymes development were investigated in the suckling rats. By the administration of dmPGE2 for 7 days, precocious induction of maltase activity, depression of amylase activity and enhancement of trypsin activity in the pancreas occurred. Absorption of bovine IgG was dose dependently depressed by dmPGE2 treatments. The intestinal cessation was also observed in the adrenalectomized pups, but was not influenced by difluoromethyl ornithine administration. These results suggest that oral administration of PGE2 induces precocious maturation of the small intestine and exocrine pancreas and that the intestinal cessation is not directly related to ornithine decarboxylase activity in the suckling rats.

Isolation and primary culture of bovine hepatocytes: albumin synthesis and adrenergic activation of glycogenolysis

We describe a technique for isolation and primary culture of bovine hepatocytes, and their metabolic characterization. Hepatocytes were isolated from the caudate lobe of bovine liver by perfusion with 0.25 mM ethylene-glycol tetraacetic acid and 0.05% collagenase. The viability and yield of the cells were 70-92% and 0.1-3.6 x 10(7) cells/g liver, respectively. When the isolated hepatocytes were cultured in Williams' medium E, they began to spread in 3 hr and formed monolayers in 24 hr. These monolayers were retained for at least 6 days. To monitor the metabolic activities specific to liver, synthesis and secretion of albumin were measured by labeling with [35S]-methionine and immunoprecipitation. This activity was low in isolated hepatocytes, but increased after culturing 1-3 days, and decreased again after 6 days. Glycogenolytic activity was also assessed by measuring glucose release to the medium by stimulation with epinephrine. The glycogenolytic response to epinephrine was also enhanced by culturing the hepatocytes 1-3 days, but was decreased after 6 days. Since the isolated bovine hepatocytes retained the liver-specific activities of albumin synthesis and glycogenolysis for several days in culture, these cells are useful for cellular and molecular studies on the functions of bovine liver.

Two different types of ADP-ribosyltransferase C3 from Clostridium botulinum type D lysogenized organisms

We examined production of ADP-ribosyltransferase C3 in 11 strains of Clostridium botulinum type C and D and their nontoxigenic derivatives. Antisera to C3 proteins of type C organisms divided C3 proteins roughly into at least two groups, bearing no relation to their bacterial types. The C3 gene of type D strain South African was isolated from a toxigenic phage library, and the complete sequence of the C3 gene was determined. The C3 protein of type D strain South African had 98% homology to the C3 protein of type C strain 003-9 and 66% homology to that of type D strain 1873. These results indicate that there are two types of C3 protein in type D organisms, as there are in type C organisms.

Purification and identification of a serum protein increased by anthelmintic drugs for Dirofilaria immitis in dogs

Polyacrylamide gel electrophoretic analysis of canine serum protein has revealed that the administration of anthelmintics elicits an increase in a certain serum protein. This protein, named PT60, was partially purified by ammonium sulfate fractionation and preparative electrophoresis. The purified PT60 gave a single band with the molecular size of 53 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis under non-reducing conditions. After reduction with 2-mercaptoethanol, two bands appeared at 35 kDa and 17 kDa, indicating that PT60 consists of two subunits which are linked with each other by disulfide bonds. PT60 had the capacity to bind to hemoglobin. In an immunodiffusion test, an antiserum against PT60 cross-reacted with canine haptoglobin (Hp). N-terminal amino acid sequences of two PT60 subunits were identical to those of alpha and beta subunits of canine Hp, respectively. Thus, PT60 was identified as Hp.

Secretin induces precocious cessation of intestinal macromolecular transmission and maltase development in the suckling rat

The effect of endogenous and exogenous secretin on the intestinal closure of macromolecular transmission and maltase development were investigated in suckling rats. The increase in secretin-like immunoreactivity with orogastric infusion of HCl solution in 14 day-old pups was confirmed. By the repeated oral administration of HCl, pancreatic hyperplasia, suppression of intestinal bovine IgG transmission, and precocious induction of maltase activity were occurred. By repeated subcutaneous injection of secretin, dose-dependent suppression of intestinal bovine IgG absorption and increase in maltase activity were observed. The suppression of IgG absorption with secretin treatment was also observed in adrenalectomized pups. These results suggest that secretin affects the maturation of gastrointestinal function in suckling rats.

Inhibition of norepinephrine secretion from digitonin permeabilized PC12 cells by botulinum type D toxin

Botulinum type D neurotoxin inhibited Ca(2+)-evoked norepinephrine secretion in digitonin permeabilized PC12 cells. Inhibition by the toxin required prior incubation with dithiothreitol (DTT). The inhibition was dependent on both concentration and incubation times of the toxin, and was affected by Ca2+ concentration. With less than 0.7 microM Ca2+ almost complete inhibition was observed; however, above 0.7 microM, Ca2+ stimulated additional norepinephrine release in a dose-dependent manner.

Precocious cessation of intestinal macromolecular transport by synthetic trypsin inhibitor in suckling rats

The effects of repeated oral administration of the synthetic trypsin inhibitor camostat on intestinal macromolecular transport and disaccharidase development were investigated in suckling rats. By daily treatment with camostat, bovine immunoglobulin (Ig) G transport in the intestine declined more rapidly in treated than in control rats. The absorption curve shifted to the left in treated rats 3 days before the controls. Morphological inspection of treated pups showed a decline in the number of epithelial cells that absorb bovine IgG and in their vesicle size from basal to upper regions of the villi. Maltase activity precociously increased with camostat treatment. Chronic subcutaneous injection of camostat did not cause any changes in IgG transport and maltase activity. The depression of IgG transport by oral treatment with camostat was not affected by the cholecystokinin (CCK) receptor antagonist L 364718 and was not inhibited by adrenalectomy. The absorptive responses of IgG and maltase activity were not affected by CCK-8 treatment. These data indicate that oral administration of camostat induces precocious maturation of the small intestine and that the effect is not mediated via endogenous CCK released by camostat.

Bovine haptoglobin: single radial immunodiffusion assay of its polymeric forms and dramatic rise in acute-phase sera

Using purified bovine haptoglobin (Hp) and specific antisera, a single radial immunodiffusion (SRID) assay method has been developed to measure the serum Hp level in cattle. Bovine Hp is a highly polymerized protein showing heterogeneous molecular forms in serum. After treatment with cysteine or glutathione, Hp was partially reduced to a homogeneous form, suitable for SRID assay. This method gives values comparable to those obtained by hemoglobin-binding capacity assay, and has the advantage of being simple and convenient. Although serum Hp was not detectable in healthy cattle, it was found more than 50-fold after invasive surgery, indicating that Hp is a characteristic acute-phase protein in cattle.

Latex agglutination test: a simple, rapid and practical method for bovine serum CRP determination

A semi-quantitative latex agglutination test for bovine serum CRP levels has been established by mixing diluted serum (or diluted standard serum) with a 1% latex suspension containing 0.489 micron latex particles coated with affinity-purified antibody at a ratio of 20 micrograms/mg latex. The agglutination was performed on a glass slide in a moist chamber at room temperature with 45 min. incubation. This test is reliable, reproducible and the results correlate with those of the single radial immunodiffusion (SRID) test. The effect of low temperature storage on CRP concentration revealed a 30% degradation of CRP during 2 years storage at 4 degrees C. The possible role of EDTA addition to prevent a decrease in serum CRP concentration by freezing and thawing is also discussed.

Cloning and whole nucleotide sequence of the gene for the light chain component of botulinum type E toxin from Clostridium butyricum strain BL6340 and Clostridium botulinum type E strain Mashike

Chromosomal DNAs were extracted from Clostridium butyricum strain BL6340 and Clostridium botulinum type E strain Mashike. The 6.0 Kbp fragment coding for the entire light chain (L) component and the N-terminus of heavy chain (H) component of botulinum type E toxin was obtained from each extracted DNAs after digestion with HindIII. The entire nucleotide sequences for the light chain components of these cloned genes were determined, and the derived amino acid sequences were compared to each other, and with those of botulinum type A, C1, D, and tetanus toxins reported previously. The cleavage site of L and H components of type E toxin was presumed to be Arg-422. In a total of 422 amino acid residues of L component, 17 residues were different between butyricum and type E toxins, and all these differences were found within 200 residues of N-terminus of L component. On the contrary, five regions showing highly homologous sequences were found in L components among these six toxins, and one more region between botulinum type E and tetanus toxins.

Epidermal cell differentiation inhibitor ADP-ribosylates small GTP-binding proteins and induces hyperplasia of epidermis

Epidermal cell differentiation inhibitor (EDIN) is a recently discovered protein which inhibits terminal differentiation of cultured keratinocytes (Sugai, M., Enomoto, T., Hashimoto, K., Matsumoto, K., Matsuo, Y., Ohgai, H., Hong, Y.-M., Inoue, S., Yoshikawa, K., and Suginaka, H. (1990) Biochem. Biophys. Res. Commun. 173, 92-98). The amino acid sequenced deduced from the EDIN gene has revealed that EDIN shares high amino acid sequence homology with the exoenzyme C3 of Clostridium botulinum (Inoue, S., Sugai, M., Murooka, Y., Paik, S.-Y., Hong, Y.-M., Ohgai, H., and Suginaka, H. (1991) Biochem. Biophys. Res. Commun. 174, 459-464), which has been shown to ADP-ribosylate the rho/rac proteins (members of the small GTP-binding protein family). We show here that EDIN ADP-ribosylates rhoB p21 in time- and dose-dependent manners in a cell-free system. Kinetic studies of the ADP-ribosylation and peptide mapping of the reaction products of rhoB p21 by EDIN and C3 suggest that the mode of action of the ADP-ribosylation by EDIN is quite similar to that by C3 and that the ADP-ribosylation site of rhoB p21 by EDIN is presumably the same as that by C3. Proteins in epidermal membranes and keratinocyte homogenate with Mr values of about 22,000 are ADP-ribosylated by EDIN or C3. Treatment of cultured human keratinocytes by EDIN or C3 results in an inhibition of terminal differentiation and a stimulation of growth of the cells. Moreover, EDIN and C3 injected into adult mouse skin induce hyperplasia of epidermis. These results suggest that EDIN and C3 affect growth and differentiation of keratinocytes by ADP-ribosylation of protein(s) with a Mr of about 22,000, which may be the rho/rac proteins or related proteins.

Purification and characterization of ADP-ribosyltransferases (exoenzyme C3) of Clostridium botulinum type C and D strains

By cation-exchange column chromatography followed by gel filtration or hydroxylapatite column chromatography, ADP-ribosyltransferases (exoenzyme C3) were isolated from culture supernatants of Clostridium botulinum type C strains Stockholm (CST) and 6813 (C6813) and from type D strains South African (DSA) and 1873 (D1873), and their molecular properties were compared. The purified C3 enzymes were homogeneous in polyacrylamide gel electrophoresis. The C3 enzymes existed as single-chain polypeptides with molecular masses of 25.0 to 25.5 kDa and transferred ADP-riboses to the same substrates in rat brain membrane extract. The C3 enzymes could be roughly classified into two groups with respect to amino acid composition, amino-terminal sequence, and antigenicity. One group contains the C3 enzymes of strains C6813 and DSA, and the other contains those of strains CST and D1873. The specific activity of the C3 enzyme of strain C6813 was about 15 times higher than that of the C3 enzyme of strain CST. These results indicate that the classification of the C3 molecules differs from that of the neurotoxin molecules.

Isolation and characterization of bovine haptoglobin from acute phase sera

A macromolecular hemoglobin-binding protein, which was not detectable in normal bovine sera but appeared during acute phase inflammation, was purified, characterized, and designated as bovine haptoglobin (Hp). The purified protein had a molecular mass of 1,000-2,000 kDa, and was composed of two kinds of peptides, a 20-kDa peptide (alpha chain) and a 35-kDa glycopeptide (beta chain) linked by disulfide bonds. Amino acid composition and N-terminal sequence analyses revealed that both peptides were homologous to each counterpart of human Hp. Studies using some reducing reagents proved that highly polymerized Hp in serum was composed of 2-20 polymerized forms of alpha 2 beta 2 tetramer. Hp could bind one molecule of hemoglobin/alpha 2 beta 2 unit. Hp with smaller sizes obtained from native Hp by partial reduction with cysteine showed almost the same Hb-binding capacity.

A new purification procedure for bovine C-reactive protein and serum amyloid P component

1. A new purification procedure was started with salting-out fractionation of serum proteins at 45-75% saturated ammonium sulfate concentration, followed by HE agarose affinity chromatography by which calcium-dependently bound CRP and SAP were purely eluted with EDTA-containing buffer. 2. Pure CRP and SAP were finally separated by DEAE-5PW HPLC. 3. This procedure gave recovery of 15 and 26%, and fold purification of 2650 and 2400 for CRP and SAP, respectively. 4. Each subunit of CRP and SAP had one intrasubunit disulfide bond, determined by reduction and carboxymethylation.

Binding of botulinum type Cl, D and E neurotoxins to neuronal cell lines and synaptosomes

Clostridium botulinum 125I-labeled Cl neurotoxin bound to NG108 hybridoma cell line. Unlabeled type Cl neurotoxin inhibited the binding of the labeled Cl toxin but neither types D nor E toxin. 125I-labeled type D neurotoxin bound to rat brain synaptosomes but did not bind to NG108 cells. It is suggested that receptors for types C and D or E toxins on neuronal cell membranes are different.

Precocious alteration of digestive enzyme activities in small intestine and pancreas by chronic oral administration of protease inhibitor in suckling rats

1. The role of endogenous CCK in the development of digestive enzyme activities in small intestine and pancreas was investigated in suckling rats. Synthetic protease inhibitor (camostat 100 micrograms/g bwt) was orally administered twice daily for 5 days from 11 days of age. 2. Pancreatic hypertrophy and hyperplasia, and alteration of pancreatic enzyme composition, especially decreases in amylase activity and increases in trypsin and chymotrypsin activities were produced by camostat treatment. These changes were completely suppressed by simultaneous administration of the potent CCK receptor antagonist L-364,718 (1 microgram/g bwt). 3. With camostat treatment, intestinal lactase activity decreased to 41%, while maltase and sucrase activities increased 3 and 2.5 times respectively. These changes in enzyme activities were not affected by the application of L-364,718. 4. The mucosal disaccharidase and pancreatic enzyme activities could not be modified by chronic subcutaneous injection of camostat. The precocious induction of maltase and sucrase activities by camostat treatment was also observed in the adrenalectomized pups. 5. These results indicate that pancreatic growth accompanied by alteration of digestive enzyme composition in the suckling rats is regulated by endogenous CCK, but the precocious induction of disaccharidase activities is not mediated by endogenous CCK released by camostat treatment.

Precocious cessation of intestinal macromolecular transmission and sucrase development induced by insulin in adrenalectomized suckling rat

1. The role of insulin in the regulatory mechanisms governing cessation of intestinal absorption of macromolecules and sucrase development was studied in the adrenalectomized suckling rat (ADX rat). 2. Intestinal absorption of bovine immunoglobulin (IgG) infused orally was dose-dependently suppressed to 35-75% in ADX rats repeatedly injected subcutaneously with insulin. 3. When insulin was administered orally, the IgG absorption was also suppressed. 4. Intestinal sucrase activity was also induced precociously by insulin administered subcutaneously and orally. 5. These results suggest that insulin plays a role in the maturation of suppression mechanisms for macromolecular transmission and sucrase development in the small intestine of the suckling rat.