Novel factor Xa and plasma kallikrein inhibitory-activities of the second Kunitz-type inhibitory domain of urinary trypsin inhibitor

Urinary trypsin inhibitor is a glycoprotein with a structure in which two Kunitz-type inhibitory domains are linked in a row. We isolated two genes encoding the 70 amino acid sequence from the 78th amino acid (Thr) to the C-terminal and the 68 amino acid sequence from the 80th (Ala) to the C-terminal of human urinary trypsin inhibitor, both which correspond to the second Kunitz-type inhibitory domain, and then constructed expression plasmids by ligating it to the E. coli alkaline phosphatase signal peptide gene. These plasmids under the control of the tryptophan promoter expressed the second domain in E. coli strain JE5505 which lacks the membrane lipoprotein. The recombinant second domain purified from the culture supernatant of the transformant inhibited trypsin, plasmin, leukocyte elastase and chymotrypsin which are known to be inhibited by urinary trypsin inhibitor. In addition it inhibited blood coagulation factor Xa and plasma kallikrein in a concentration dependent and competitive manner, and significantly prolonged the plasma-based activated partial thromboplastin time (APTT). The truncated natural counterpart obtained by a limited degradation of human urinary trypsin inhibitor also revealed the identical inhibitory activities.

Purification and biochemical characterization of a recombinant mouse seminal vesicle trypsin inhibitor produced in Escherichia coli

Escherichia coli cells were transformed with an expression vector constructed by inserting a DNA fragment encoding a Kazal-type trypsin inhibitor from mouse seminal vesicle into pGEX-2. The cloned cells were able to produce a high yield of a chimeric polypeptide made by fusing the trypsin inhibitor to glutathione S-transferase. The chimeric polypeptide could be purified through an affinity column of glutathione agarose beads. The purified protein could be digested with thrombin to release the recombinant trypsin inhibitor which could be further purified by HPLC of the thrombin digests on a reverse-phase C4 column. The recombinant trypsin inhibitor was homogeneous and showed trypsin inhibitor activity as strong as that of the naturally occurring trypsin inhibitor.

Synthesis and expression of a gene coding for Erythrina trypsin inhibitor (ETI)

A gene coding for Erythrina trypsin inhibitor (ETI) was designed, based on the published N-terminal sequence of the protein, and synthesized by an oligonucleotide-directed single strand break-repair mechanism. Direct expression from the expression vector pBtac1 was unsuccessful. A construct, encoding an extended methionyl N-terminal amino acid was expressed from the vector pET12a which supplies a signal sequence for export to the periplasm. Most of the expressed protein was located in the cytoplasm but because the periplasm is an environment conducive to the formation of disulphide bridges, only periplasmic protein was extracted. Cyanogen bromide cleavage at the sole methionyl residue removed the undesired amino acid residues that remained after signal sequence peptidase processing. The resultant ETI was assayed against trypsin and tissue plasminogen activator and found to have activity similar to that of natural ETI.

Biosynthesis of bikunin (urinary trypsin inhibitor) in rat hepatocytes

One of the major sulfated proteins secreted by rat hepatocytes contains a low-sulfated chondroitin sulfate chain and its apparent molecular mass upon sodium dodecyl sulfate/polyacrylamide gel electrophoresis shifts from 40 to 28 kDa upon chondroitinase ABC treatment (E. M. Sjöberg and E. Fries, 1990, Biochem. J. 272, 113-118). These properties suggest that this protein is the rat homologue of the major trypsin inhibitor of human urine which was recently named bikunin. In serum, bikunin occurs mainly as a subunit of the pre-alpha-inhibitor and the inter-alpha-inhibitor; in these proteins it is covalently linked to the other polypeptides through its chondroitin sulfate chain. Bikunin has been shown to be synthesized by liver cells as a 42-kDa precursor, in which it is linked to alpha 1-microglobulin by two basic amino acids. We have isolated bikunin from rat urine and prepared antibodies against it. In rat hepatocytes pulse-labeled with [35S]methionine, these antibodies precipitated a labeled protein of 42 kDa. Upon chase, three different labeled proteins were recognized by the antibodies in the medium: one protein of 40 kDa (free bikunin), one of 125 kDa (presumably pre-alpha-inhibitor), and one greater than 240 kDa (possibly a protein related to the inter-alpha-inhibitor). Pulse-chase experiments with [35S]sulfate showed that these proteins occurred intracellularly as precursors containing alpha 1-microglobulin. These results demonstrate that the completion of the chondroitin sulfate chain and its coupling to other polypeptide chains occur before the cleavage of the alpha 1-microglobulin/bikunin precursor.

Biosynthesis of inter-α-trypsin inhibitor and α1-microglobulin in a human hepatoma cell line

1. Biosynthesis of alpha 1-microglobulin and inter-alpha-trypsin inhibitor was investigated in a human hepatoma cell line HepG-2. 2. alpha 1-Microglobulin was translated as a precursor common with the light chain of inter-alpha-trypsin inhibitor. 3. alpha 1-Microglobulin was synthesized and secreted into the growth medium within 30 min. 4. Processing of inter-alpha-trypsin-inhibitor-related proteins appeared slow and incomplete. The light chain was connected via a chondroitinsulphate to a heavy chain to form a 125,000-Mr protein and secreted within 1-4 hr.

Human urinary trypsin inhibitor (urinastatin)-like substance in mouse liver

Mouse liver contains a human urinary trypsin inhibitor (urinastatin, UT)-like immunoreactive substance with trypsin inhibitory activity. Northern blot analysis demonstrates the presence of the appropriate 1.3 kb mRNA band in liver tissue but not in kidney or other tissues examined. Administration of hydrocortisone, which is known to increase the urinary excretion of the UT-like substance, increased the levels of UT-like substance in serum and in the liver tissue. In contrast, deoxycorticosterone acetate did not have such an effect. These results suggest that the gene encoding UT-like substance is primarily expressed in the liver of the mouse, and that glucocorticoids play an important role in regulating the hepatic synthesis of UT-like substance. Furthermore, these findings indicate that the mouse is a suitable species for research on the biological function of UT or UT-like substances.

Synthesis of a wild-type and three mutant Cucurbita maxima trypsin inhibitor-encoding genes by a single-strand approach

A single-strand approach to gene assembly, based on a modification of an in vitro complementary oligodeoxyribonucleotide template-directed ligation of the desired sequence to a linearized vector [Chen et al., Nucleic Acids Res. 18 (1990) 871-878], is described. The gene coding for the wild-type Cucurbita maxima trypsin inhibitor of 29 amino acid residues [Bode et al., FEBS Lett. 242 (1989) 285-292], as well as three mutant forms of the gene, in which two of the three disulfide bonds have been replaced singly or as a pair, have been synthesized in a single synthesis run with minimal manual intervention. Subsequent to ligation to pUC9 and in vivo gapped duplex repair by Escherichia coli, their sequences have been verified.

Production of trypsin and chymotrypsin inhibitors by oral bacterial isolates

Using an agar-skim milk gel method, over 300 oral bacterial isolates were tested for their ability to produce trypsin or chymotrypsin inhibitor. Eleven bacterial strains, including seven isolates identified as Bacteroides intermedius, were found to inhibit both proteolytic activities. The inhibitory factors of the 11 bacterial strains could be divided into two categories: i) heat-stable and dialysable, and ii) heat-labile and non-dialysable. The protease inhibitor activity of B. intermedius strains, which belongs to the latter category, was found in a membrane fraction as well as in a membrane-free extract. Furthermore, three strains of B. intermedius showed this inhibitory activity in the culture supernatant. In combination with plasma-derived protease inhibitors, the production of these additional protease inhibitors by oral bacteria could protect the host from tissue degradation.

Coordinate estrogen-regulated instability of serum protein-coding messenger RNAs in Xenopus laevis

Estrogen causes the cytoplasmic destabilization of albumin and gamma-fibrinogen mRNA in Xenopus laevis liver. The purpose of the present study was to determine whether mRNA destabilization is a generalized phenomenon in response to estrogen, or whether this process is restricted to a particular class of mRNAs. To address this, we have expanded our bank of serum protein-coding cDNA clones to include transferrin, the second protein of inter-alpha-trypsin inhibitor and clone 12B, for which there is no mammalian homolog. Together with albumin and gamma-fibrinogen, these represent more than 85% of the mRNAs encoding liver secreted proteins. Estrogen administration to male Xenopus or to liver explant cultures causes the generalized disappearance of all of these mRNAs. In contrast, estrogen has no effect on actin, ferritin, or poly(A)-binding protein mRNA, all of which encode intracellular proteins. We have previously demonstrated that albumin mRNA is degraded in both messenger ribonucleoprotein and polysome fractions. Sucrose gradient analysis demonstrates the same pattern for degradation of all other serum protein-coding mRNAs. Estrogen has no effect on the amounts or gradient distribution of actin, ferritin, or poly(A)-binding protein mRNA. We conclude that regulated destabilization of mRNAs encoding secreted proteins is a generalized phenomenon in response to estrogen stimulation of Xenopus liver.

Response to IL-6 stimulation of human hepatoblastoma cells: production of pancreatic secretory trypsin inhibitor

LPS-stimulated macrophage conditioned medium and IL-6 markedly stimulated the secretion of PSTI by cultured hepatoblastoma cells. The mechanism underlying the cellular response of IL-6-induced secretion of PSTI was investigated. Among the agents affecting the signal transduction pathways, forskolin significantly induced PSTI secretion whereas PMA or A23187 did not, suggesting that IL-6 induced PSTI secretion is mediated by cAMP dependent protein kinase A.

Human inter-alpha-trypsin inhibitor. Synthesis and maturation in hepatoma HepG2 cells

In hepatoma HepG2 cells, human inter-alpha-trypsin inhibitor (ITI) was synthesized as three heavy chains, H-1 (100 kDa), H-2 (110 kDa) and H-3 (113 kDa), and light hybrid chain (49.5 kDa) composed of alpha 1-microglobulin and HI-30 (ITI derivative, human inhibitor of 30 kDa). The association of at least two heavy chains, H-1 and H-3, with the HI-30 part of the light chain gave rise to a molecule similar to serum ITI. A composite protein (approximately 250 kDa) including heavy and light chains was also secreted, while alpha 1-microglobulin and ITI H-2 protein were released as separate entities. Light chain synthesis could be the limiting factor for ITI maturation.

Production of extracellular trypsin and chymotrypsin inhibitors by a Streptomyces Sp

The production of extracellular inhibitors by Streptomyces sp. 1-72, specific either to trypsin (TI-1), or to chymotrypsin (CI-1), was investigated in relation to the cell growth and composition of the cultivation media. The biosynthesis of the inhibitors was found to be of a growth-associated type which reached a maximum level at late exponential phase. All of the investigated carbon sources, including starch, disaccharides and monosaccharides, equally supported the production of both inhibitors, while the effect of the different nitrogen sources considerably varied, some of them being totally ineffective. The sources which mostly supported the biosynthesis of the inhibitors were tryptone (3%) for TI-1, and peptone (3%) for CI-1 respectively.

Synthesis of contrapsin and alpha-1-antiproteinase in inflamed and tumor-bearing mice

In mice bearing ascites tumors, such as Ehrlich, L1210, Meth-A, and P-815, the plasma levels of contrapsin and alpha-1-antiproteinase remained virtually unchanged. However, the total body pools of these proteins as well as their hepatic mRNA levels increased severalfold, and isoelectrofocusing patterns of these proteins shifted to the lower pH side. Under the same conditions, plasma albumin level decreased by 25%, but its total body pool and hepatic mRNA level increased severalfold. On the other hand, induction of acute phase reaction by injection of bacterial lipopolysaccharide caused differential effects on the two proteinase inhibitors: hepatic translatable mRNA for contrapsin was doubled while that for alpha-1-antiproteinase remained unchanged.

Possible lysosomal activation of pancreatic zymogens. Activation of both human trypsinogens by cathepsin B and spontaneous acid. Activation of human trypsinogen 1

Human trypsinogens 1 and 2 were activated at the same rate by pure human cathepsin B at pH 3.8. Human trypsinogen 1 was also spontaneously activated during incubation at acidic pH, activation being most rapid at pH 5.0. In contrast, trypsinogen 2 showed little or no activation under these conditions. The presence of calcium salts (20mM) delayed the onset of activation under all conditions tested. These findings support the proposal that premature activation of the pancreatic zymogens may result from their entry into the lysosomal system in pancreatitis.

Production of recombinant human pancreatic secretory trypsin inhibitor by Escherichia coli

A synthetic gene for human pancreatic secretory trypsin inhibitor (PSTI) was fused to the coding sequence for the amino-terminal 135 amino acid residues of human interferon-gamma (IFN-gamma) by interposing a methionine codon sequence, and the resulting hybrid gene was efficiently expressed in Escherichia coli cells. Recombinant human PSTI (rHu-PSTI) was separated from the IFN-gamma/PSTI fused protein by cleavage at the methionine residue with cyanogen bromide. Finally, rHu-PSTI was purified by affinity chromatography on a bovine trypsin-CH-Sepharose 4B column. The amino acid composition, partial amino-terminal sequence, disulfide formation, human trypsin inhibitory activity, and immunoreactivity against rabbit anti-human PSTI serum of rHu-PSTI corresponded to those of the natural form.

cDNA cloning of human inter-alpha-trypsin inhibitor discloses three different proteins

Inter-alpha-trypsin inhibitor (ITI) is a serum protein of unknown function. Part of the molecule (formerly called HI30) is closely related to a tumor-derived protein acting as a growth factor for endothelial cells. We screened a human liver cDNA expression library with antibodies raised against human ITI and isolated several clones which could be divided into three groups according to their DNA sequences. The cDNA of the first group codes for a protein composed of alpha 1-microglobulin (alpha 1M) and urinary trypsin inhibitor (UTI) and is identical to that encoded by a clone originally found by screening a human liver cDNA library with oligonucleotides derived from amino-acid sequences of the two Kunitz-type domains of UTI. The proteins derived from the cDNA of the second and the third group of clones are distantly related to each other, but unrelated to the protein derived from group 1 clones. Partial amino-acid sequencing of ITI isolated from serum allowed the verification of large parts of the cDNA-derived amino-acid sequences. The results favour the view that ITI is not a single chain protein, but rather a very tight complex of several components or a mixture of such complexes.

Low-molecular-weight trypsin inhibitors of microbial origin

Three hundred actinomyces cultures newly isolated from the soil of different regions of the Soviet Union were tested for their ability to produce inhibitors of trypsin-like proteases. Seven previously not known to produce trypsin inhibitors (Streptomyces bikiniensis 17-5, S. sporoclivatus 28-1, S. filamentosus 32-11, S. diastatochromogenes 20-4, S. lavendulae 29-4, S. violacens 52-8, and Streptoverticillium cinnamoneum 36-8) were found to possess high antitrypsin activity. The morphological and cultural properties of the strains and the dynamics of inhibitor production were investigated. S. bikiniensis 17-5 was studied in greatest detail. Its culture filtrate contained several inhibitors for trypsin and one for chymotrypsin. A mixture of oligopeptides with Mr of 300-500 was obtained by the described procedure which included the adsorption of the culture fluid filtrate on charcoal followed by ion-exchange chromatography on CM-cellulose. Four trypsin inhibitors (Sb-IT1, Sb-IT2, Sb-IT3, and Sb-IT4) were isolated from the mixture in a highly purified state by reversed-phase high-performance liquid chromatography. Sb-IT2 has been recognized as formylhistidylvaline with an Mr of 282. No trypsin inhibitor of this structure has been described previously.

Pancreatic secretory trypsin inhibitor-like immunoreactivity in pancreatectomized patients

Pancreatic secretory trypsin inhibitor (PSTI) is a 6000-dalton peptide, that occurs in high concentrations in the pancreas and in pancreatic juice. It is thought to be synthesized by pancreatic acinar cells. We have recently reported the findings of an identical trypsin inhibitor at high concentrations in the urine of patients with gynecological malignancy. Therefore, we have named the inhibitor tumor-associated trypsin inhibitor (TATI). We have now studied patients who have undergone total pancreatoduodenectomy for pancreatic cancer or chronic pancreatitis. By radioimmunoassay (RIA), we found normal levels of this inhibitor in the serum and urine of pancreatectomized patients. The absence of pancreas was confirmed by measuring serum trypsin. By gel filtration and HPLC it was found that PSTI/TATI occurring in pancreatectomized patients was indistinguishable from that found in connection with pancreatitis and ovarian cancer.

Pattern of serum protein gene expression in mouse visceral yolk sac and foetal liver

We have shown by molecular hybridisation that the mRNAs for albumin, transferrin, apolipoprotein-A1, and alpha 1-antitrypsin are expressed at high levels in mouse visceral yolk sac. In contrast, the mRNAs for contrapsin (a plasma protease inhibitor) and the major urinary proteins (MUPs) are not detected in the visceral yolk sac at any stage of embryonic development. Contrapsin and MUP mRNAs both appear late in liver development. These differences in expression suggest that the visceral yolk sac is more similar to the foetal than adult mouse liver in its pattern of gene expression. However, the developmental time course of expression of these mRNAs is different between the foetal liver and the yolk sac. Evidence is also presented that the visceral yolk sac synthesises and secretes other apolipoproteins in addition to apolipoprotein-A1. These results suggest that the visceral yolk sac and foetal liver, two tissues with different embryological lineages, perform similar functions but are independently programmed for expression of the same set of serum protein genes.

Inter-alpha-trypsin-inhibitor (ITI): two distinct mRNAs in baboon liver argue for a discrete synthesis of ITI and ITI derivatives

Human serum inter-alpha-trypsin-inhibitor (ITI) has so far been assumed to be comprised of a single polypeptide chain which can undergo fragmentation, whereby inhibitory ITI derivatives are released into the blood stream. In contrast, the analysis of the baboon liver mRNA translation products showed that ITI is made up of heavy and light chain(s). The latter may be excreted independently and very likely corresponds to the so-called ITI derivatives.

Trypsin inhibitor of Streptomyces griseus grown in a carbon nutrition medium

Streptomyces griseus grown in beef extractpeptone medium produces trypsin inhibitors which are both peptide and protein in nature. When the strain was grown in carbon nutrition medium, only one trypsin inhibitor was obtained. Similar elution patterns of this inhibitor and the TI-3a inhibitor obtained from the beef extract-peptone medium on Sephadex G-15 and ion-exchange columns and also the RF values indicate that the inhibitors from both the sources are the same. So, TI-3a is not the breakdown product of the protein inhibitor of S. griseus.

Production of trypsin inhibitor by a Cephalosporium sp

Conditions for the production of the trypsin inhibitor from Cephalosporium sp. KM 388 were investigated. Polypeptone-meat extract-glucose medium supported excellent production of the trypsin inhibitor. In this medium, polypeptone and meat extract were utilized both as carbon and nitrogen sources and as limiting substrates for the cell growth. Glucose was consumed during the stationary growth phase and prevented the disappearance of inhibitor activity. Cephalosporium sp. KM 388 grew at a rate of a first-order reaction for the cell concentrations. Trypsin inhibitor production paralleled cell growth. At 27 degrees C the maximum specific rates of growth and inhibitor production were 0.14 h-1 and 2.1 U of inhibitor/h per mg of cell, respectively. The production rate and the maximum yield of the inhibitor were increased 1.5- and 1.2-fold, respectively, when the initial pH 6.3 was maintained throughout the fermentation.

[Search for actinomycetes that produce inhibitors of proteolytic enzymes]

The inhibiting activity of filtrates of the cultural broth against trypsin and chymotrypsin was studied among 66 actinomycetes. The highest activity against trypsin was found, after selection, in the following cultures: Act. janthinus 118, Act. violatus 125, Act. violaceus confinus 2476, Act. violaceus vicinus 1074. The antitrypsin activity was detected in the cultural broth of Act. janthinus 118 during the first day of its growth, and reached maximum by the third day. The inhibiting substance in the cultural broth is thermo- and pH-stable, is not extracted with organic solvents, and remains in the bag during dialysis. Apparently, the inhibitor (s) of trypsin produced by Act. janthinus 118 differes from trypsin inhibitors of microbial origin and low molecular weight which have been described so far.

Development of gamma G, gamma A, gamma M, beta IC-beta IA, C 1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, plasminogen, alpha 1-antitrypsin, orosomucoid, beta-lipoprotein, alpha 2-macroglobulin, and prealbumin in the human conceptus

The synthesis of gammaG, gammaA, gammaM, beta(1C)/beta(1A), C'1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, alpha(1)-antitrypsin, orosomucoid, beta-lipoprotein, alpha(2)-macroglobulin, and prealbumin was studied in 15 normal human embryos and fetuses of 29 days to 18 wk gestation and in the yolk sacs of four embryos from 5.5 to 11.5 wk gestation using tissue culture in (14)C-labeled amino acids followed by radioimmunoelectrophoresis. The human embryo as early as 29 day gestation synthesized beta(1C)/beta(1A), C'1 esterase inhibitor, transferrin, hemopexin, alpha(1)-antitrypsin, beta-lipoprotein, alpha(2)-macroglobulin, and prealbumin in culture. At 32 days gestation ceruloplasmin and orosomucoid were also synthesized, but synthesis of fibrinogen was not observed before 5.5 wk. Synthesis of gammaM occurred as early as 10.5 wk gestation, and gammaG synthesis was found in cultures as early as 12 wk gestation; gammaA synthesis was not detected in any of the tissue cultures. With the exception of the gamma-globulins, each of the proteins studied was synthesized by the liver, but additional sites of synthesis for some of these proteins were also found. Synthesis of gammaG and gammaM occurred primarily in the spleen, but other sites of synthesis were noted as well. Changes in the concentrations of most of these proteins and plasminogen in embryonic and fetal serum from 5.5 to 41 wk gestation, in amniotic fluid from 6.5 to 38 wk gestation, and in the sera of neonates during the 1st 3 wk postpartum are described. Although gammaA, gammaM, ceruloplasmin, or haptoglobin were not detectable in some of the embryonic and fetal sera, gammaA and ceruloplasmin were both present as early as 6.5 wk gestation, haptoglobin by 9.5 wk gestation, and gammaM by 17 wk gestation. Each of the other proteins were present in all of the sera examined.