Proliferation-related nucleolar antigens P145 and P120 associated with separate nucleolar elements and differences in tissue distribution.

Nucleolar antigens p145 and p120 are associated with proliferating cells (Freeman, J.W.; McRorie, D.K.; Busch, R.K.; Gyorkey, P.; Gyorkey, F.; Ross, B.E.; Spohn, W.H.; Busch, H. Cancer Res. 46:3593; 1986 and Freeman, J.W.; Busch, R.K.; Gyorkey, P.; Gyorkey, F.; Ross, B.E.; Busch, H. Cancer Res. 48:1244; 1988) and are not detectable in normal resting cells. Recent immunoelectron microscopic studies (Ochs, R.L.; Reilly, M.T.; Freeman, J.W.; Busch, H. Cancer Res. 48:6523; 1988) suggest that the two antigens have overlapping nucleolar localizations. In this study the nucleolus was physicochemically and biochemically studied to determine whether p145 and p120 were associated with a common nucleolar component. Antigen p145 was associated with 40-80 S ribonucleoprotein particles (RNPs), and the p145 antigen was not detected in HeLa cells following in situ RNAse digestion. P120 was found in a 40-80 S, RNAse resistant complex. Sequential extraction of HeLa nucleoli showed that most of antigen p145 was extractable in 10 mM Tris with 0.2% deoxycholate, whereas p120 was found in a nucleolar residue fraction requiring DNAse and high salt treatment for optimal extraction. Neither antigen p145 nor p120 was detectable in normal resting tissues. Antigen p145 was detected in all proliferating tissues examined, including a variety of malignant tumors (ten of ten), benign tissues including adenomas and hyperplasias (eight of eight), and in normal proliferating cells such as colonic epithelium and spermatogonia of the testes. Antigen p120 was not detected in all tumors, being absent in three of seven lymphomas and in one melanoma examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Optimal loading of scraped HeLa cells with monoclonal antibodies to the proliferation-associated Mr 120,000 nucleolar antigen.

Our laboratory has reported (J. W. Freeman et al., Cancer Res., 48:1244-1251, 1988) a proliferation-associated Mr 120,000 nucleolar antigen (p120), that was found in human tumors but was not detectable in most normal resting tissues and in benign tumors. To study further the function and the localization of this protein, we have investigated various methods of microinjecting p120 monoclonal antibodies into cells. For comparison, we have used a monoclonal antibody to protein C23, a nucleolar protein found in high levels in most cells. To determine optimal conditions for loading of antibodies to nucleolar antigens into mechanically disrupted HeLa cells, we studied the effects of ionic strengths of loading buffers, various antibody concentrations, and optimal time for loading and antibody localization. With ascites fluids in isotonic buffer containing antibodies to nucleolar proteins p120 and C23, a maximum number of cells, 86 and 84%, respectively, were loaded following a 20-min incubation. Hypotonic buffers decreased the percentage of cells loaded (22%); hypertonic buffers reduced cell viability. The optimal concentration of purified antibody yielding a maximum number of loaded cells (81%) was 2.5 mg/ml. Higher concentrations of antibody resulted in residual cytoplasmic staining without increasing the percentage of loaded cells. With antibody concentrations less than 2.5 mg/ml, a linear decrease was noted in the percentage of cells loaded with a decrease in intensity of fluorescence. Following antibody loading, nucleolar fluorescence was observed by 12 h and the intensity increased at 24 h. Localization of the p120 antibody was followed through mitosis where it was perichromosomal and equally divided between the chromosomes at metaphase. A decrease of nucleolar immunofluorescence intensity and percentage of cells labeled were observed in successive cell generations.

Endothelial prostacyclin production is a late event in granulocyte migration into bovine pulmonary artery intimal explants.

Whether migration of granulocytes across pulmonary vascular endothelium in the absence of structural evidence of endothelial injury causes increased production of thromboxane or prostacyclin is not known. Using bovine pulmonary artery intimal explants mounted in Boyden chambers and homologous separated granulocytes, concentrations of thromboxane B2 and 6-keto-PGF1 alpha in the upper-well fluid were measured by radioimmunoassay over a three-hour period under the following conditions: (1) granulocyte chemotaxis (zymosan-activated plasma in the lower well, granulocytes in the upper well); (2) unstimulated granulocyte migration (serum or plasma in the lower well, granulocytes in the upper well); (3) granulocyte activation without migration (zymosan-activated plasma and granulocytes in the upper well); (4) granulocyte chemotaxis in the absence of endothelium (identical to condition 1 above except that endothelium was scraped from the explant surface); and (5) explants incubated in the absence of granulocytes. Minimal increases in thromboxane B2 concentrations in upper-well fluid occurred under all conditions. In contrast, granulocyte chemotaxis was accompanied by large increases in concentrations of 6-keto-PGF1 alpha evident by two hours of incubation and increasing markedly by three hours, to 524.3 +/- 69.0 ng/mL (m +/- SEM). Unstimulated migration of granulocytes toward serum or plasma and granulocyte activation without migration were accompanied, at three hours, by more modest increases in 6-keto-PGF1 alpha (296.5 +/- 46.4; 128.0 +/- 38.6, and 236.7 +/- 47.0 ng/mL, respectively) and, in the absence of granulocytes or in the absence of endothelium, only minimal increases in this prostacyclin metabolite occurred (137.2 +/- 16.9 and 53.9 +/- 12.6 ng/mL, respectively). The large rises in prostacyclin metabolite occurred at a time when the majority of granulocytes had migrated through the endothelial layer rather than during their adherence or transendothelial passage. We conclude that chemotaxis of granulocytes through pulmonary vascular endothelium causes endothelial production of large amounts of prostacyclin, but this occurs late in the chemotactic process, after granulocytes have transversed the endothelium.