Expression of Two Late Adenovirus Genes Is Altered by Introducing Antibodies against Ribonucleoprotein into Living HeLa Cells

Abstract

These experiments describe the effect on adenovirus gene expression of tranfusing liposome-encapsulated antibodies directed against a 10-S ribonucleoprotein complex into infected Hela cells. Immunoprecipitation studies demonstrate that this particular serum contains antibodies directed against particles containing U1 RNA and five polypeptides in the molecular weight range of 45 000 -60000. The procedure of fusing liposomes successfully treats nearly all the cells in culture, and the transfused material has access throughout the cell. The IgG fraction from this serum is introduced into adenovirus-infected cells shortly before the transition from the early to the late stage of the lytic cycle; 19 h after fusion the accumulated effects of the antibodies on late virus expression are examined by pulse-labeling cells with radioactive methionine and observing the synthesized proteins. While most late viral genes are expressed normally in treated cells, fiber synthesis is reduced to a very low level and hexon synthesis is reduced twofold. That most viral genes are expressed normally demonstrates that many cell activities (transcription, transport, processing and translation) are minimally affected. The effects on these two genes can be distinguished by varying the concentration of antibody transfused : interference with hexon synthesis occurs at a lower dosage than fiber. A simple interpretation of these results is that the antibody has bound to its antigen and prevented the latter from participating in its role in message processing.

The composition of the nuclear antigens Sm and RNP of human rheumatic and connective tissue diseases and the relevance of their autoantibodies as probes for RNA processing mechanisms

“…The striking exception to this overall view is the difference in analyses of HeLa RNP found in [4,12]. Using preparations and procedures apparently identical to those in [4], the latter group identified 5 proteins (M, 45 000-60 000) as being associated with RNP antigen (although significant amounts of proteins with iV2, > 60 000 and <40 000, including a 10 000 Mr group, were also present).…”

“…As in the case of Sm, it is significant that the very small RNA molecules are obtained when RNP is prepared from thymus nuclei [9,18,19,21]. However, it should be noted that extended exposure of autoradiograms of RNA gels containing RNPimmunoprecipitates showed the presence of at least 2 additional small RNA components with mobilities between 4 Sand 5 S RNA [12].…”

“…Where qualitative differences have been reported, these tend to refer to highMr proteins (cf. [4] and [12,. Lerner et al [3,4,6,7] and Lenk et al [ 121 have shown that RNP antigen from several cell sources contains only U, as the dominant snRNA species, yet other laboratories find that in their preparations either the U, is accompanied by identified plus unidentified snRNAs [ 131 or the RNA consists only of very small species [9,18,19].…”

“…In addition, White and Hoch [23], using a 'blotting' technique, have observed significant differences in the proteins reacting with anti-Sm/RNP sera that are both of a species (for antigen) and patient (for antibody) origin. The striking differences found in the proteins associated with HeLa RNP antigen by two laboratories [4,12] have also been interpreted as indicating variations in the detailed specificity of anti-RNP sera from different patients [ 121. Hence some degree of antibody specificity for Sm and RNP at a molecular level cannot be dismissed, even in sera from patients with the same clinically defined condition.…”

Characterization by human autoantibody of a nuclear antigen related to the cell cycle.

“…Circulating autoantibodies occurring in various human autoimmune disorders are of great interest for defining different nuclear antigens (for a review, see Tan, 1982). They are convenient tools for characterizing the corresponding molecular structures (Lerner et al, 1979) and for elucidating the basic functions of these structures in cell metabolism (De Robertis et al, 1982;Yang et al, 1981;Lenk et al, 1982). For this purpose, the most extensively studied anti-nuclear antibodies are found in systemic rheumatic diseases.…”