Linkage of transcobalamin II (TC2) to the P blood group system and assignment to chromosome 22

The linkage relationships of transcobalamin II (TC2) against 64 other marker systems are studied in a Danish family material (families 604-1505). A strong indication of linkage between TC2 and the blood group system P was discovered (z = 7.91 at theta = 0.14 for males and theta = 0.20 for females combined). Accordingly, TC2 could be assigned to chromosome 22 (since blood group P has earlier been assigned to this chromosome).

Hormonal regulation of extracellular plasminogen activators and Mr approximately 54,000 plasminogen activator inhibitor in human neoplastic cell lines, studied with monoclonal antibodies

We have studied the regulation by glucocorticoids and dibutyryl cAMP of the amounts of urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA) and a Mr approximately 54000 plasminogen activator inhibitor accumulated in serum-free conditioned culture fluid by a human fibrosarcoma, a human glioblastoma and a human melanoma cell line (HT-1080, UCT/gl-1 and Bowes). For the quantitation of u-PA and t-PA, we used sandwich-type ELISA with a combination of polyclonal and monoclonal antibodies. For an estimation of variations in the amount of the inhibitor, we used sodium dodecyl sulphate-polyacrylamide gel electrophoresis followed by Coomassie blue staining of conditioned culture fluid proteins, the inhibitor protein band being identified by its selective removal by passage of the conditioned culture fluids through a column with monoclonal antibodies against the inhibitor. The modulation of the 3 proteins by the hormonal agents varied greatly between the cell lines. The proteins were independently regulated, in the sense that the hormonal agents did not concomitantly change their levels in the direction expected either to increase or decrease total extracellular plasminogen activator activity. In conditioned culture fluids containing both t-PA and inhibitor, the two were present in the medium as a Mr approximately 120 000 complex. In contrast, no u-PA inhibitor complexes were found in conditioned culture fluid from any of the cell lines; this is likely to be due to the occurrence of u-PA in the culture fluid in the one-chain proenzyme form, which, unlike active u-PA, does not react with the inhibitor. These findings illustrate the complexity of the regulation of extracellular plasminogen activator activity, and imply that the presumed functional diversity of u-PA and t-PA may be related to their independent regulation.

Monoclonal antibodies to human 54,000 molecular weight plasminogen activator inhibitor from fibrosarcoma cells--inhibitor neutralization and one-step affinity purification

Mouse monoclonal antibodies were derived against a plasminogen activator inhibitor with a mol. wt. of approximately 54,000 (54 K) from the human fibrosarcoma cell line HT-1080. Screening for hybrids producing antibodies directed against the inhibitor was performed with enzyme-linked immunosorbent assay and SDS-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting. Four clones of hybridomas producing IgG1 antibodies were further characterized. The inhibitor was purified approximately 50-fold to homogeneity from conditioned cell culture fluid with a yield of approximately 85% by a one-step procedure using Sepharose-conjugated monoclonal antibody. In the 125I-fibrin plate assay one of the antibodies neutralized the effect of the inhibitor on urokinase-type plasminogen activator. Two of the antibodies bound complexes between urokinase-type plasminogen activator and inhibitor while the remaining two antibodies did not. The antibodies could be used for immunocytochemical localization of the inhibitor in HT-1080 cells. All four antibodies cross-reacted with a plasminogen activator inhibitor derived from cultured human umbilical cord endothelial cells.

Plasminogen activators catalyse conversion of inhibitor from fibrosarcoma cells to an inactive form with a lower apparent molecular mass

Purified approximately 54 kDa plasminogen activator inhibitor from human fibrosarcoma cells was converted to an inactive form with slightly higher electrophoretic mobility by incubation with catalytic amounts of urokinase-type or tissue-type plasminogen activator. Serine proteinase inhibitors and a monoclonal antibody against urokinase-type plasminogen activator inhibited the conversion, indicating that it was caused by plasminogen activator-catalyzed proteolysis. These findings represent the first demonstration of a well-defined protein apart from plasminogen, constituting a substrate for plasminogen activators.

Tissue-type plasminogen activator in rat adrenal medulla

Rat adrenal glands were stained immunocytochemically using antibodies against plasminogen activators of the tissue-type (t-PA) and urokinase-type (u-PA). A subpopulation of the cells in the adrenal medulla showed intense cytoplasmic t-PA immunoreactivity, while no u-PA immunoreactivity was detected in any adrenal cells. Fluorescence microscopy of adjacent sections demonstrated that the cells stained for t-PA contained noradrenaline. Analysis with a histochemical fibrin slide technique demonstrated a plasminogen-dependent fibrinolysis in the adrenal medulla. SDS-PAGE of adrenal gland extracts followed by zymography established the molecular weight of this plasminogen activator to be similar to that of rat t-PA. In addition SDS-PAGE followed by immunoblotting with anti-t-PA IgG of adrenal gland extracts revealed one band with an electrophoretic mobility indistinguishable from that found in the zymography. When tissue-sections and immunoblots were incubated with antibodies absorbed with highly purified t-PA no staining was found. In view of the previous finding of t-PA in growth hormone-containing cells of the pituitary gland, these findings substantiate that t-PA can be found in the intact normal organism outside endothelial cells, and further point to t-PA having a function in endocrine cells.

General detection of proteins after electroblotting by trinitrobenzene sulphonic acid derivatization and immunochemical staining with a monoclonal antibody against the trinitrophenyl group

A sensitive method for the general detection of proteins electroblotted onto nitrocellulose sheets after separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis is described. The proteins on the blots were reacted with 2,4,6-trinitrobenzene sulphonic acid. The resulting trinitrophenyl groups on the proteins were rendered visible by immunochemical staining with a monoclonal anti-trinitrophenyl antibody, and a peroxidase-conjugated second antibody. Using various proteins, the method was compared to the amidoblack method for staining of protein blots. The method was 10-100-fold more sensitive than the amidoblack method. Amounts as low as 1 ng of human serum albumin could be detected.

Plasminogen and tissue-type plasminogen activator bind to immobilized fibronectin

Fibronectin immobilized onto polystyrene surface was found to bind plasminogen and tissue-type plasminogen activator (t-PA) but only slightly the urokinase type as determined using mono- and polyclonal antibodies against the activators. Of the defined fibronectin fragments tested, the Mr 120,000-140,000 fragment was found to bind both plasminogen and t-PA. Proteolytically modified plasminogen (Lys-plasminogen) bound considerably better than the native form (Glu-plasminogen). Experiments with 125I-plasminogen yielded Kd = 9.1 X 10(-8) M for the binding to immobilized fibronectin. The partially or completely inactive single-chain form of t-PA (pro-t-PA) bound considerably better than the activated two-chain form. Lysine at greater than 3 mM inhibited the binding of plasminogen. The interaction was independent of calcium ions. CaCl2 (greater than 0.5 mM) and NaCl (greater than 0.2 M) inhibited the binding of pro-t-PA and of t-PA. Fibronectin-bound t-PA retained its ability to activate plasminogen. The observed interactions may operate in directional proteolysis localizing plasminogen and plasminogen activator to degrade fibronectin-containing extracellular matrix including fibrin clots.

Linkage relationships of paraoxonase (PON) with other markers: indication of PON-cystic fibrosis synteny

The linkage relationships of the serum arylesterase paraoxonase (PON) was examined in our Danish material of normal families and in Danish and English cystic fibrosis families. Highest lod scores were found between PON and cystic fibrosis. The combined lod score for this relationship was z = 2.69 at theta = 0.07 in males and theta = 0.00 in females. When scored in accordance with a tentative three allele model for PON, the score was z = 3.70 at the same theta values. Linkage studies for PON against 64 other polymorphic marker systems did not give any lod score above +1.3 and PON still remains chromosomally unassigned. By the present screening about 2/3 of the genome could tentatively be excluded as the region of PON and cystic fibrosis.

HLA determinants in idiopathic haemochromatosis

HLA-antigens were determined in 21 unrelated patients with idiopathic haemochromatosis and in eight siblings and 13 children of the probands. The prevalences of HLA-A3, B7, and B14 in patients compared to 1967 healthy control subjects were: A3, 76.2% versus 26.9% (p less than 0.0001); B7, 57.1% versus 26.8 (p less than 0.001); B14, 9.5% versus 4.5% (n.s.); A3 and B7, 42.9% versus 12.2% (p less than 0.0001); A3 and B14, 9.5% versus 1.4% (p less than 0.001). Siblings (n = 3) that were HLA-identical with the proband were considered to be homozygotes for the haemochromatosis allele and presented with preclinical haemochromatosis. Siblings and children (n = 17) having only one HLA-haplotype in common with the proband were considered to be heterozygotes. Biochemical markers for haemochromatosis (transferrin saturation and serum ferritin) were higher in homozygous than in heterozygous subjects (p less than 0.0001). The results confirm the association between the HLA-A and B loci and the haemochromatosis gene. HLA-typing is a valuable tool in the identification of the haemochromatosis genotype in a family, and it is an adjunct to the biochemical screening procedure in relatives of patients with this iron overload disorder.

Plasminogen activator in psoriatic scales is of the tissue-type PA as identified by monoclonal antibodies

Extracts of scale from four patients with psoriasis all contained plasminogen activator. All plasminogen activator activity was of the tissue-type (t-PA) as judged from the following criteria: all enzyme activity was inhibited by a monoclonal antibody against human t-PA, while there was no measurable inhibition by a monoclonal antibody against human urokinase-type plasminogen activator (u-PA); as determined by zymography the extracts contained one type of plasminogen activator which had an electrophoretic mobility identical to that of purified t-PA; this plasminogen activator was removed by passage through a Sepharose column coupled with a monoclonal antibody against t-PA, but not by passage through a column coupled with a monoclonal antibody against u-PA. On a molar basis the detection limit for u-PA was 10% of that of t-PA present.

Immunocytochemical demonstration of tissue-type plasminogen activator in endocrine cells of the rat pituitary gland

We immunocytochemically stained rat pituitary glands using antibodies against plasminogen activators of the tissue type (t-PA) and the urokinase type (u-PA). A large population of endocrine cells in the anterior lobe of the gland displayed intense cytoplasmic immunoreactivity with anti-t-PA. In some areas of the intermediate lobe we found a weak staining, and we observed weakly staining granular structures in the posterior lobe. Controls included absorption of the antibodies with highly purified t-PA. In addition, SDS PAGE followed by immunoblotting of pituitary gland extracts revealed only one band with an electrophoretic mobility similar to that of t-PA when stained with anti-t-PA IgG. No u-PA immunoreactivity was detected in the rat pituitary gland. Sequential staining experiments using antibodies against growth hormone and t-PA demonstrated that the t-PA-immunoreactive cells constitute a large subpopulation of the growth hormone-containing cells. These findings represent the first direct evidence for the presence of t-PA in cell types other than endothelial cells in the intact normal organism. In this article we discuss the implications of the results for a possible role of t-PA in the posttranslational processing of prohormones.

Proenzyme to urokinase-type plasminogen activator in the mouse in vivo

We have investigated whether urokinase-type plasminogen activator (u-PA) is present in the mouse in vivo as the proenzyme or as the active enzyme. u-PA in extracts of various murine tissues was of a one-polypeptide chain form with an electrophoretic mobility indistinguishable from purified proenzyme (pro-u-PA), as demonstrated by SDS-polyacrylamide gel electrophoresis under reducing conditions followed by immunoblotting. No 2-chain u-PA was detected in any of the extracts (detection limit 10% of that of one-chain u-PA). In bladder urine more than half of the u-PA was of the one-chain form. Together with previous immunocytochemical studies of the normal murine tissues and studies of the Lewis lung carcinoma, the present results indicate that in these tissues the one-chain proenzyme is the predominant form of u-PA in intracellular stores and for the first time demonstrates that at least in some cases the one-chain form constitutes a sizeable fraction of the u-AP in extracellular fluids in the intact organism.

Confirmation of F13A assignment and sequence information concerning F13A-HLA-GLO

The polymorphism of the blood clotting factor F13A was examined in some of our Danish material of normal families. A total of four alleles were recognized, with allele frequencies as follows: F13A *1 = 0.817, F13A *2 = 0.177, F13A *4 = 0.003 and a new allele F13A *5 = 0.003. The distribution of unrelated individuals did not deviate significantly from the Hardy-Weinberg expectation. Linkage of F13A with HLA was confirmed (z = 5.18, theta = 0.17 in males and z = 0.14, theta = 0.37 in females). The sequence of the three systems F13A, HLA and GLO was found to be F13A-HLA-GLO as judged from two families each with a recombinant within the HLA system in males.

Immunocytochemical localization of urokinase-type plasminogen activator in Lewis lung carcinoma

The invasively growing and metastasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA.

Linkage of plasma alpha-L-fucosidase (FUCA2) and the plasminogen (PLG) system

Plasma fucosidase (FUCA2) was examined by means of a technique using p-nitrophenyl-alpha-L-fucopyranoside as substrate. The material consisted of normal Danish families, including 1,672 unrelated persons (parents). In this material the low activity allele frequency was found to be plow = 0.286 which agrees with earlier studies in European populations. The allele frequencies did not differ significantly between the sexes. Segregation ratios agreed with the hypothesis that 'low' is due to an autosomal recessive allele. Our results give a strong indication of linkage for FUCA2-PLG (z = 7.37 theta = 0.12) in males, and the linkage may be considered as formally demonstrated. The PLG-system as judged from our indication of linkage with GC (z = 2.35, theta = 0.30 in males) is then possibly located on chromosome 4p (Eiberg et al. 1981).

Human endothelial cells contain one type of plasminogen activator

At least two types of animal plasminogen activating enzymes exist, differing in amino acid sequence, molecular mass and immunological reactivity: the urokinase-type and the tissue-type plasminogen activators. By affinity chromatography with monoclonal antibodies, we have purified the human activators of both types to homogeneity. Using immunocytochemistry with rabbit antibodies raised against these preparations, we now demonstrate that the plasminogen activator present in endothelium of veins and other blood vessels is of the tissue-type. No urokinase-type plasminogen activator immunoreactivity was detected in endothelial cells in the intact organism. These findings support the assumption that mobilization of plasmin for different purposes may involve different types of plasminogen activators, and that the plasminogen activator involved in thrombolysis is of the tissue-type.

Distribution of urokinase-type plasminogen activator immunoreactivity in the mouse

Immunocytochemistry, using rabbit antibodies to a urokinase-type 48-Kdalton Mr mouse plasminogen activator, showed that enzyme immunoreactivity is widely distributed in the normal mouse. Strong staining was obtained in widely disseminated connective tissue cells with a fibroblast-like morphology. Such cells occurred in high numbers in the lamina propria mucosae of the gastrointestinal tract, and in moderate numbers in the connective tissue septa of the pancreas. A few such cells were detected around the larynx, trachea, and bronchi. Immunoreactivity also occurred in epithelial cells of the proximal and distal kidney tubules, the ductus deferens, and in pulmonary pneumocytes. In addition, presumably extracellular staining was seen irregularly along the basement membrane and fibrillar structures in the lamina propria of the small and large intestines. Moreover, decidual cells of the mouse placenta stained strongly, and a moderate staining was observed in epithelial cells of involuting mammary glands, but not in those of noninvoluting glands. No immunoreactivity was observed in endothelial cells. Control experiments included absorption of the antibodies against highly-purified mouse plasminogen activator and the corresponding proenzyme, and the finding of a good correspondence between the number of immunoreactive cells and measurable enzymatic activity determined in adjacent tissue sections. Separation by SDS PAGE followed by immunoblotting revealed only one immunochemically stainable protein band with Mr approximately 48 Kdaltons in extracts from tissues showing immunoreactivity.

Inactive proenzyme to tissue-type plasminogen activator from human melanoma cells, identified after affinity purification with a monoclonal antibody

The human 66 000 mol. wt. plasminogen activator (HPA66; tissue-type plasminogen activator) has been purified from melanoma cells by a one-step affinity method with a monoclonal antibody. HPA66 purified in this way consists mainly of a one-polypeptide chain form with small amounts (15%) of a form containing two polypeptide chains held together by one or more disulphide bridges. The one-chain form was converted to the two-chain form by catalytic amounts of plasmin. During the conversion, the enzyme activity of HPA66, as measured by an [125I]plasminogen conversion assay and with a chromogenic substrate, increased linearly with the percentage of the two-chain form. A linear regression analysis showed that all enzyme activity could be accounted for by the two-chain form, while the one-chain form had no measurable enzyme activity (detection limit approximately 5% of the activity of the two-chain form). Together with previous findings of inactive proenzymes to murine and human approximately 50 000 mol. wt. (urokinase-type) plasminogen activators, these findings indicate that plasminogen activators are generally formed from inactive one-chain proenzymes which are converted to active two-chain enzymes by limited proteolysis, thus demonstrating a third step in a cascade reaction leading to extracellular proteolysis.

Genetics and linkage relationships of the C3 polymorphism: discovery of C3-Se linkage and assignment of LES-C3-DM-Se-PEPD-Lu synteny to chromosome 19

The C3 complement system was examined in our Danish material of normal families, which had earlier been examined for 59 marker systems, and in a myotonic dystrophy family material. A total of 8 alleles were recognized, with allele frequencies as follows: C3*S = 0.7902, C3*F = 0.2018, C3*S rare (3 lumped together) = 0.0036, C3*F rare (2 lumped together) = 0.0024; a silent allele was recognized in three families and its frequency estimated to C3*QO = 0.002. The distribution of unrelated individuals did not deviate significantly from the Hardy-Weinberg expectation, it was not significantly different between the sexes, and for none of the mating types was there any significant deviation from the expected ratios of children. As to linkage relationships of C3 with marker systems and with myotonic dystrophy, there was evidence (most of it first presented at the 6th International Congress of Human Genetics, Jerusalem 1981) for synteny with ABH secretion (Se): C3-Se (males) z = 4.35, theta = 0.12 and with Lewis secretion (LES): C3-LES (males z = 3.63, theta = 0.04). There were indicative or suggestive lod scores for Se-PEPD (males & females z = 2.41, theta = 0.00), C3-Lu (z = 1.88, theta = 0.15), C3-DM (z = 1.69, theta = 0.06) and PEPD-C3 (male z = 0.95, theta = 0.17). The most likely sequence of these 6 systems would appear to be LES-C3-DM-(Se-PEPD)-Lu and the synteny would reside on chromosome 19.

delta-Aminolevulinatedehydrase: synteny with ABO-AK1-ORM (and assignment to chromosome 9)

A material comprising 846 normal families from the Copenhagen area (fam. no. 604-1505) was tested for delta-aminolevulinatedehydrogenase. Among the 1697 unrelated individuals (parents), the gene frequencies were 0.9378 for ALADH 1 and 0.0622 for ALADH 2. The distribution of phenotypes and the segregation ratios did not deviate significantly from the expected values. Linkage analysis was carried out for markers on chromosome 9, following up a hint of ALADH-ORM linkage in part of the material. This was confirmed, and the most likely sequence, as judged from male theta values, was found to be ABO-AK1-ALADH-ORM. The theta and z values were as follows: ABO-AK1 (theta = 0.13, z = 6.27), ABO-ALADH (theta = 0.21, z = 5.38), ABO-ORM (theta = 0.27, z = 5.06), AK1-ORM (theta = 0.17, z = 1.63), ALADH-ORM (theta = 0.13, z = 7.05) and AK1-ALADH (theta = 0.11, z = 2.45).

Monoclonal antibody to human 66,000 molecular weight plasminogen activator from melanoma cells. Specific enzyme inhibition and one-step affinity purification

Hybridomas producing a monoclonal IgG1 antibody to a human plasminogen-activating enzyme with an apparent mol. wt. of 66,000 (66 K, HPA66) from human melanoma cells were obtained by fusion of NSI-Ag 4/1 mouse myeloma cells with spleen cells from a mouse immunized with a partially purified preparation of the enzyme. Screening for clones of hybridomas producing antibodies to HPA66 was performed with the impure enzyme preparation. A preliminary screening included enzyme-linked immunosorbent assay and SDS-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting; the final identification was based on inhibition of the enzymatic activity of HPA66 which was complete at high antibody concentrations. No inhibition of three other human and murine plasminogen activators or of plasmin was observed. Employing a one-step affinity procedure with the antibody coupled to Sepharose, HPA66 was purified approximately 200-fold from conditioned medium from the melanoma cells with a yield of 79%. The purified HPA66 was homogeneous as evaluated by SDS-PAGE. Electrophoresis under reducing conditions indicated that it consisted of one polypeptide chain. The binding constant between the antibody and 125I-labelled HPA66 was approximately 2.5 x 10(9) l/mol. The antibody did not bind to a variety of other plasminogen activators, including 52-K and 36-K human enzymes and 48-K and 75-K murine enzymes. Previously, a monoclonal antibody against another enzyme was derived by the sole use of enzyme inhibition for screening. The present study represents a modification of this procedure that can be used when antibody-unrelated inhibitors of the enzyme are present in hybridoma culture fluid.

Purification of zymogen to plasminogen activator from human glioblastoma cells by affinity chromatography with monoclonal antibody

Incorporation of the serine protease active site reagent diisopropyl fluorophosphate (DFP) into a plasminogen activator with an Mr of approximately 52000 released from cultured human glioblastoma cells was strongly enhanced by incubation with plasmin. This observation led to the isolation of an inactive form of the enzyme from serum-free conditioned culture fluid by affinity chromatography on a column of a Sepharose-bound monoclonal antibody raised against urokinase. An 831-fold purification was obtained with a yield of 41%. The purified molecule was homogeneous as evaluated by polyacrylamide gel electrophoresis with sodium dodecyl sulfate (NaDodSO4), having one stainable band under nonreducing as well as reducing conditions with an Mr of approximately 52000. It was unable to activate plasminogen, but catalytic amounts of plasmin converted it into active enzyme. After NaDodSO4-polyacrylamide gel electrophoresis, the active enzyme showed one band under nonreducing conditions, but after reduction, two bands with Mr values of approximately 20000 and 32000 were observed. The active enzyme incorporated [3H]DFP into the approximately Mr 32000 band, while no incorporation was observed into the inactive form. These findings show that the Mr 52000 human plasminogen activator exists in a proenzyme form consisting of a single polypeptide chain that by proteolysis between half-cystine residues is converted into the active enzyme consisting of two chains with molecular weights of approximately 20000 and 32000, the active site being on the latter chain. The results are consistent with the active form of the enzyme being identical with the higher molecular weight form of urokinase, and together with recent observations that a murine plasminogen activator is released from sarcoma virus transformed cells as an inactive proenzyme, they suggest that zymogens to plasminogen activators are of more general occurrence.