Identification of mRNA Coding for Factor VII Protein in Human Alveolar Macrophages - Coagulant Expression May Be Limited Due to Deficient Postribosomal Processing

Clotting factors synthesized by monocytes and macrophages may initiate coagulation reactions during inflammation. Functional vitamin K-dependent coagulation factors have been found to be associated with human monocytes/macrophages, but there are no reports identifying mRNA coding for vitamin K-dependent proteins in these cells. In the present studies, factor VII mRNA was found in total RNA extracted from freshly isolated human alveolar macrophages using hybridization with a complementary DNA probe. On the other hand, vitamin K-dependent carboxylase activity which is required for postribosomal modification of the protein, was not detectable in the macrophages before or after culture, and human blood mononuclear leukocytes also lacked this enzyme activity. Control human and rat hepatoma cells exhibited high levels of carboxylase activity within the same experiments. Using sensitive kinetic assays, no increase in factor VII activity was detected during culture of alveolar macrophages under conditions promoting 1.78 ± .24 (n = 8) fold increases of tissue factor activity. These findings with freshly isolated cells demonstrate that alveolar macrophages synthesize factor VII mRNA in vivo. However, the mRNA was found in the absence of evidence for γ-carboxylase activity or processing of the factor into a functional clotting enzyme. The results imply that functional expression of any synthesized coagulation factor VII in alveolar macrophages may be limited or prevented due to a cellular deficiency at the level of postribosomal processing.

Keywords

Tissue factor - Factor VII - Vitamin K - Alveolar macrophages

• References

• 1 Rothberger H, Dove F, Lee TK, McGee MP, Kardon B. Procoagulant activity of lymphocyte-macrophage populations in rabbits; selective increases in marrow, blood and spleen cells during Shwartzman reactions. Blood 1983; 61: 712-717
• 2 Rothberger H, McGee MP, Lee TK. Tissue factor activity. A marker of alveolar macrophage maturation in rabbits. Effects of granulomatous pneumonitis J Clin Invest 1984; 73: 1524-1531
• 3 Rothberger H, McGee MP. Generation of factor V activity by cultured rabbit alveolar macrophages. J Exp Med 1984; 164: 1880-1890
• 4 Chapman HA, Allen CL, Stone OL, Fair DS. Human alveolar macrophages synthesize factor VII in vitro. Possible role in interstitial lung disease J Clin Invest 1984; 75: 2030-2037
• 5 Wallin R, Rannels S, Martin LF. DT-diaphorase and vitamin Independent carboxylase in liver and lung microsomes and in macrophages and type II epithelial cells isolated from rat lung. Chem Scr 1987; 27 A 193-202
• 6 Wallin R, Rannels SR. Identification of vitamin K-dependent carboxylase activity in lung type II cells but not in lung macrophages. Biochem J 1988; 250: 557-563
• 7 Fair DS, Marlar RA. Biosynthesis and secretion of factor VII, protein C, protein S and the protein C inhibitor from a human hepatoma cell line. Blood 1986; 67: 64-70
• 8 Koren SH, Devlin RB, Graham DE, Mann R, McGee MP, Horstman DH, Kozumbo WJ, Becker S, House DE, McDonnell WF, Bromberg PA. Ozone-induce inflammation in the lower airways of human subjects. Am Rev Resp Dis. (in press)
• 9 Rothberger H, Zimmerman TS, Spiegelberg HL, Vaughan JH. Leukocyte procoagulant activity. Enhancement of production in vitro by IgG and antigen-antibody complexes J Clin Invest 1977; 59: 549-557
• 10 Covington M, Fleenor D, Devlin RB. Analysis of xanthine dehydrogenase mRNA levels in mutants affecting expression of the Rosy locus. Nucleic Acids Res 1984; 12: 4559-4573
• 11 O’Hara PJ, Grant FJ, Haldeman BA, Gray CL, Insley MY, Hagen FS, Murray MJ. Nucleotide sequence of the gene coding for human factor VII, a vitamin K-dependent protein participating in blood coagulation. Proc Natl Acad Sci 1987; 84: 5158-5162
• 12 Wallin R, Martin LF. Early processing of prothrombin and factor X by the vitamin K-dependent carboxylase. J Biol Chem 1988; 263: 9994-10001
• 13 Doellgast G, Rothberger H. Enzyme-linked coagulation assay. II. A sensitive assay for tissue factors and factors II, VII, and X. Anal Biochem 1986; 152: 199-207
• 14 Nemerson Y, Gentry R. An ordered addition, essential activation model of the tissue factor pathway of coagulation: Evidence for a conformational cage. Biochemistry 1986; 25: 4020-4033
• 15 Nemerson Y. Tissue factor and hemostasis. Blood 1988; 71: 1-8
• 16 Schmith RL. Titration of activated bovine factor X. J Biol Chem 1973; 248: 2418-2423
• 17 Laemmli UK. Cleavage of structural proteins during the assembly of the bacteriophage. Nature 1970; 277: 680-685
• 18 Sitrin RG, Kaltreider HB, Ansfield MJ, Webster RO. Procoagulant activity of rabbit alveolar macrophages. Am Rev Respir Dis 1984; 128: 282-287
• 19 Weisberg LJ, Shiu DT, Conkling PR, Shuman MA. Identification of normal human peripheral blood monocytes and liver as sites of synthesis of coagulation factor XIII a-chain. Blood 1987; 70: 579-582
• 20 Austin SA, Kay JE. Translational regulation of protein synthesis in eukaryocytes. In: Essays in biochemistry 1982; 18: 79-120
• 21 Malhotra OP. Partially carboxylated prothrombins. I. Comparison of activation properties and purification of 1- and 0-carboxyglutamyl variants. Biochim Biophys Acta 1982; 702: 178-184
• 22 Haskill S, Johnson C, Eierman D, Becker S, Warren K. Adherence induces selective mRNA expression of monocyte mediators and protooncogenes. J Immunol 1988; 140: 1690-1694