TY - JOUR
T1 - Effects of actinomycin D analogs on nucleolar phosphoprotein B23 (37,000 daltons/pI 5.1)
AU - Yung, Benjamin Y.M.
AU - Busch, Rose K.
AU - Busch, Harris
AU - Mauger, Anthony B.
AU - Chan, Pui Kwong
PY - 1985/11/15
Y1 - 1985/11/15
N2 - Localization of protein B23 in HeLa cells after treatment with actinomycin D and its analogs was studied using indirect immunofluorescence. Bright nucleolar fluorescence was observed in control HeLa cells. After treatment with actinomycin D (250 ng/ml) for 2 hr, a uniform nucleoplasmic fluorescence was observed. Similar results were obtained with the actinomycin analogs, actinomycin Z5 and actinomycin K2T. Only after a much longer incubation (24 hr) with actinomycin 4-4′-gly was nucleoplasmic fluorescence observed. Actinomycin D, actinomycin Z5, and actinomycin K2T inhibited [3H]uridine incorporation into the trichloroacetic acid insoluble fraction of HeLa cells with IC50 values of 9.5 ± 3.2, 59.1 ± 19.6 and 1423.3 ± 212.2 ng/ml respectively. No inhibition of [3H]uridine incorporation was observed using actinomycin 4-4′-gly (2000 ng/ml, 2-hr incubation). The order of potency for the loss of nucleolar fluorescence and the concurrent increase in nucleoplasmic fluorescence was actinomycin D > actinomycin Z5 > actinomycin K2T > actinomycin 4-4′-gly, which correlated with the order of their IC50 values for inhibition of [3H]uridine incorporation. Studies of the effects of actinomycin D and its analogs on RNA synthesis and localization of protein B23 indicated that there is a direct relationship between the B23 "translocation" from nucleolus to nucleoplasm and the inhibition of RNA synthesis. At 45-55% inhibition of RNA synthesis, both nuclear and nucleolar B23 immunofluorescence were observed. At 75-85% inhibition, only a uniform nucleoplasmic fluorescence was observed.
AB - Localization of protein B23 in HeLa cells after treatment with actinomycin D and its analogs was studied using indirect immunofluorescence. Bright nucleolar fluorescence was observed in control HeLa cells. After treatment with actinomycin D (250 ng/ml) for 2 hr, a uniform nucleoplasmic fluorescence was observed. Similar results were obtained with the actinomycin analogs, actinomycin Z5 and actinomycin K2T. Only after a much longer incubation (24 hr) with actinomycin 4-4′-gly was nucleoplasmic fluorescence observed. Actinomycin D, actinomycin Z5, and actinomycin K2T inhibited [3H]uridine incorporation into the trichloroacetic acid insoluble fraction of HeLa cells with IC50 values of 9.5 ± 3.2, 59.1 ± 19.6 and 1423.3 ± 212.2 ng/ml respectively. No inhibition of [3H]uridine incorporation was observed using actinomycin 4-4′-gly (2000 ng/ml, 2-hr incubation). The order of potency for the loss of nucleolar fluorescence and the concurrent increase in nucleoplasmic fluorescence was actinomycin D > actinomycin Z5 > actinomycin K2T > actinomycin 4-4′-gly, which correlated with the order of their IC50 values for inhibition of [3H]uridine incorporation. Studies of the effects of actinomycin D and its analogs on RNA synthesis and localization of protein B23 indicated that there is a direct relationship between the B23 "translocation" from nucleolus to nucleoplasm and the inhibition of RNA synthesis. At 45-55% inhibition of RNA synthesis, both nuclear and nucleolar B23 immunofluorescence were observed. At 75-85% inhibition, only a uniform nucleoplasmic fluorescence was observed.
UR - http://www.scopus.com/inward/record.url?scp=0022345553&partnerID=8YFLogxK
U2 - 10.1016/0006-2952(85)90387-9
DO - 10.1016/0006-2952(85)90387-9
M3 - 文章
C2 - 2415133
AN - SCOPUS:0022345553
SN - 0006-2952
VL - 34
SP - 4059
EP - 4063
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 22
ER -