Nuclear distribution pattern of tumour-associated nonhistone protein of mol. wt 48,000

1. As a further step toward characterizing nonhistone protein of mol. wt 48,000 which was found to be much more abundant in animal tumour cells than in normal ones [Krajewska W.M., Lipínska A., Marszatek M., Kiliańska Z., Wojtkowiak Z. and Kłyszejko-Stefanowicz L. Cell. Biochem. Funct. 8, 79-89 (1990)] its intranuclear localization in hamster liver and Kirkman-Robbins hepatoma was studied. The protein was identified by immunoblotting technique in the presence of antibodies against polypeptide of mol. wt about 48,000 from Kirkman-Robbins hepatoma. 2. Distribution of antigen with mol. wt of 48,000 in nuclear fractions representing different levels of nuclear material organization, i.e. in nucleoli, nuclease-sensitive and nuclease-resistant fractions, and extensive nuclease digestion products separated by size on Bio-Gel A-50m; implied the structural role of this component. 3. Fractionation of endogenously digested nuclei into low salt extract, high salt extract and nuclear matrix revealed that in normal liver the antigen studied is associated with nuclear matrix while in hepatoma this component appeared in high salt extract. 4. These results suggest that polypeptide with mol. wt of 48,000 is a shuttling protein which may be involved in reorganization of nuclear matrix during neoplastic transformation.

Nuclear antigen with a molecular weight of 48,000 associated with malignant transformation

1. Analysis of immunoblots of one- and two-dimensional electropherograms of non-histone proteins from Kirkman-Robbins hepatoma, Morris hepatoma 7777, regenerating liver and normal liver demonstrated the presence of elevated level of nuclear antigen with mol. wt of 48,000 and pI of 5.4 in tumour cells. 2. Small amounts only were detected in proliferating and quiescent cells suggesting that different expression of this component may reflect biochemical events related to malignant transformation rather than to general cell activation.

Studies on low molecular weight nuclear protein of tumour and normal cells

1. Preliminary results of comparative electrophoretical and immunological analyses of the components of two classes of non-histone proteins, i.e. NHP1 and NHP2 eluted from hydroxyapatite allowed to suppose that protein of Mw 18,000 is specific for animal tumour cells. 2. However, the studies on cellular distribution of this polypeptide indicated that it is exclusively located in nuclei of hepatoma and normal liver as well. 3. The former observation seems to be the result of changes of the affinity of this protein to DNA during neoplastic transformation.

Identification of a nuclear antigen with molecular weight of 48,000 differentially expressed in tumour and normal cells

A non-histone protein with mol. wt of 48,000 differentially expressed in normal and tumour cells was identified using immunological criteria. Antibodies were raised against a component specific for Kirkman-Robbins hepatoma of mol. wt about 48,000 separated from hepatoma non-histone proteins by preparative electrophoresis in polyacrylamide gel. It was demonstrated by immunoblotting that Morris hepatoma 7777 and Ehrlich ascites cells share an antigenic non-histone protein with Kirman-Robbins hepatoma. Tumour cells when compared with normal cells, i.e. hamster and rat liver, are characterized by significant enrichment of this component. Intracellular distribution of the polypeptide with mol. wt 48,000 suggests that this component may be a structural protein the biosynthesis of which increases or the antigenic determinants of which change in tumour cells.

Cellular distribution of the hamster liver specific nucleolar antigens

The immunochemical localization of hamster liver nucleolar antigens in subcellular fractions (nuclei, 10,000 x g pellet, 100,000 x g pellet and supernatant), nuclear substructures (chromatin, nuclear matrix, nuclear envelope, nucleoli, RNP particles and nucleosomes), and three classes of nonhistone chromosomal proteins with different affinities to DNA (NHCP1, NHCP2 and NHCP3) from nuclease-sensitive and nuclease-resistant chromatin fractions of hamster liver were studied. Six main nucleolar antigens with mol. wts 27,000; 29,000; 30,000; 36,000; 45,000; and 46,000 were found in subcellular fractions, nuclear substructures and classes of non-histone proteins of hamster liver. The antigens with mol.wts of approx. 27,000; 29,000; and 36,000 which were absent in hamster pancreas, spleen and Kirkman--Robbins hepatoma nuclei, seem specific for liver tissue.

Hamster liver chromatin immunospecific non-histone proteins

Three antisera were prepared against non-histone protein classes named NHCP1, NHCP2 and dehistonized chromatin (with different affinity to DNA) from hamster liver. Two main antigenic bands of MW 17,000 and 36,000 were specific in the NHCP1 fraction and one antigen of MW 56,000 was specific for the NHCP2 fraction from nuclease-sensitive and especially nuclease-resistant chromatin. Other NHCP2 liver antigens of MW 22,000, 27,000, 30,000, 36,000, 37,000, 40,000, 45,000, 46,000, 51,000, 98,000 and 100,000 were present only in nuclease-resistant chromatin of hamster liver. Immunologically specific hamster liver non-histone proteins within the NHCP1 and NHCP2 fractions seem to be restricted to nuclease-resistant chromatin fraction of this tissue. The above mentioned liver specific antigens are absent or present only at trace amounts in analogous Kirkman-Robbins hepatoma fractions.

Molecular and functional diversity of non-histone protein fraction NHCP1 from hamster Kirkman-Robbins hepatoma and liver

Non-histone protein fraction NHCP1 of micrococcal nuclease-sensitive and nuclease-resistant chromatin from Kirkman-Robbins hepatoma and hamster liver was studied by two-dimensional electrophoresis followed by Coomassie and silver staining and by microcomplement fixation technique in the presence of antibodies elicited against NHCP1 of both tissues. Apart from many common spots several tissue specific components associated with either nuclease-sensitive or nuclease-resistant chromatin were found. The presence of tissue specific components among NHCP1 from hepatoma and liver was confirmed by immunological analysis. It was stated that these components are exclusively localized in nuclease-resistant part of chromatin from neoplastic and normal tissues thus suggesting their structural function.

Chicken erythrocyte chromatin and nuclear envelope antigens

Chromatin and inner layer nuclear envelope were isolated from chicken erythrocyte nuclei. Two antisera against dehistonized chromatin and nuclear envelope of chicken erythrocytes were obtained. Using the antiserum against dehistonized chromatin of erythrocytes we found: the presence of the antigens at approximate mol. wts of 56,000 and 77,000 tightly bound with DNA and characteristic of only erythrocyte chromatin; localized antigens at approximate mol. wts of 63,000, 68,000 and 92,000 tightly bound with DNA and common only for chromatin and nuclear envelope of chicken erythrocytes; heterogeneity of the antigens tightly bound with DNA. Using the antiserum against inner layer nuclear envelope we did not find antigens specific only for nuclear envelope and absent in erythrocyte chromatin. Some of the antigens were present in the control preparations of chicken liver chromatin and may be regarded as being species specific.

Chromatin proteins associated with micrococcal nuclease-sensitive and nuclease-resistant chromatin fractions of Kirkman-Robbins hepatoma and hamster liver

Micrococcal nuclease-sensitive (SP) and nuclease-resistant (PP) chromatin fractions from Kirkman-Robbins hepatoma and hamster liver were obtained. The molecular distribution of three non-histone proteins (NHCP1, NHCP2 and NHCP3), histones, and chromatin-bound protease activity between SP and PP fractions of both tissues was compared. Differences, mainly of quantitative nature, among non-histone proteins of neoplastic and normal tissue were observed. Moreover, it was found that polypeptides with mol. wt 81 000 (NHCP1), 39 000 (NHCP2) and 21 000, 35 000, 37 000 (NHCP1), 70 000, 112 000, 141 000, 157 000 (NHCP2), 30 000-33 000 (NHCP3) were associated only with the nuclease-sensitive part of chromatin of hepatoma and normal tissue, respectively. A major difference in histone composition of hamster hepatoma and liver concerns histones H2A and H1. Furthermore, an enrichment of high mobility group proteins as well as other soluble non-histone proteins in an acid extract of the SP fraction was observed. Apparently chromatin-bound protease activity can be found in both fractions of chromatin.

Distribution of non-histone proteins between micrococcal nuclease sensitive and nuclease resistant chromatin from chicken cells with active and inactive genomes

Chicken liver and erythrocyte nuclei were separated by mild treatment with micrococcal nuclease into nuclease sensitive (NS) and nuclease resistant (NR) fractions, differing in chemical composition and transcriptional activity in vitro. Nuclei, NS and NR fractions of both tissues were fractionated by hydroxyapatite chromatography into three groups of non-histone chromatin proteins (NHCP) and characterized by SDS-polyacrylamide gel electrophoresis. Some differences in the molecular distribution of non-histone proteins of chicken liver and erythrocytes between nuclease sensitive and resistant parts of chromatin have been described.

Effects of chromatin protein fractions on transcriptional activity of chicken thrombocyte and erythrocyte chromatin

1. Chromatin proteins of chicken thrombocytes and erythrocytes were separated into three fractions by successive extraction with 5 M urea containing various salt concentrations and pH values. Molecular composition of protein fractions was determined by SDS-polyacrylamide gel electrophoresis. 2. The efficiences of the chromatin residues after sequential protein extractions as well as those of reconstituted DNA-protein fraction complexes, in serving as a template for the in vitro RNA synthesis were measured in order to identify the effect of each fraction. 3. The different involvement of chromatin protein fractions of template properties of thrombocyte and erythrocyte chromatin was stated.