Alpha-Amanitin resistance of RNA polymerase II in mutant Chinese hamster ovary cell lines.

Mutants resistant to the RNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofurano-sylbenzimidazole (DRB) have been isolated in the Chinese hamster ovary cell line CHO-K1. Three independently isolated mutants, DRB6 DRB10, and DRB13, were 3-, 5-, and 3.5-fold, respectively, more resistant to DRB than the parental cell line WTCHO. The DRB-resistant mutations were expressed codominantly in somatic cell hybrids of DRB-resistant and DRB-sensitive cell lines. In vivo treatment of CHO-K1 cells with DRB resulted in specific inhibition of endogenous RNA polymerase II activity in cell lysates. Whereas DRB inhibited RNA polymerase II activity in WTCHO cells by a maximum of 60% at concentrations as low as 60 microM, 300 microM DRB was required to inhibit 60% of the RNA polymerase II activity in DRB10 cells. However, the inhibition of the DRB-sensitive RNA polymerase II activity in DRB10 was biphasic. About half (53 to 56%) of this activity was inhibited by 90 microM DRB and thus showed a DRB sensitivity similar to the wild-type RNA polymerase II activity; the remaining DRB-sensitive RNA polymerase II activity was maximally inhibited by 300 microM DRB. These results indicated that there were two copies of the drbR locus (drb+ and drbR-10) in DRB10 and confirmed that the drbR-10 mutation was expressed codominantly. Somatic cell hybrids of DRB-resistant and alpha-amanitin-resistant cell lines grew in medium containing both DRB and alpha-amanitin, demonstrating that the drbR and amaR mutations were not in the same gene. Thus, the drbR mutations may define an additional component of the RNA polymerase II transcriptional complex in mammalian cells.

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The RNA polymerase II of an α-amanitin-resistant Chinese hamster ovary cell line

Cell ◽

10.1016/0092-8674(76)90186-0 ◽

1976 ◽

Vol 8 (1) ◽

pp. 65-70 ◽

Cited By ~ 32

Author(s):

Peter E. Lobban ◽

Louis Siminovitch ◽

C.J. Ingles

Keyword(s):

Rna Polymerase ◽

Rna Polymerase Ii ◽

Cell Line ◽

Chinese Hamster Ovary Cell ◽

Chinese Hamster Ovary ◽

Chinese Hamster ◽

Ovary Cell ◽

Ovary Cell Line

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Isolation and characterization of 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole-resistant mutants of the Chinese hamster ovary cell line

Molecular and Cellular Biology ◽

10.1128/mcb.2.4.467-477.1982 ◽

1982 ◽

Vol 2 (4) ◽

pp. 467-477

Author(s):

V L Funanage

Keyword(s):

Rna Polymerase ◽

Somatic Cell ◽

Rna Polymerase Ii ◽

Cell Line ◽

Chinese Hamster Ovary ◽

Chinese Hamster ◽

Ovary Cell ◽

Somatic Cell Hybrids ◽

Ovary Cell Line ◽

Alpha Amanitin

Mutants resistant to the RNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofurano-sylbenzimidazole (DRB) have been isolated in the Chinese hamster ovary cell line CHO-K1. Three independently isolated mutants, DRB6 DRB10, and DRB13, were 3-, 5-, and 3.5-fold, respectively, more resistant to DRB than the parental cell line WTCHO. The DRB-resistant mutations were expressed codominantly in somatic cell hybrids of DRB-resistant and DRB-sensitive cell lines. In vivo treatment of CHO-K1 cells with DRB resulted in specific inhibition of endogenous RNA polymerase II activity in cell lysates. Whereas DRB inhibited RNA polymerase II activity in WTCHO cells by a maximum of 60% at concentrations as low as 60 microM, 300 microM DRB was required to inhibit 60% of the RNA polymerase II activity in DRB10 cells. However, the inhibition of the DRB-sensitive RNA polymerase II activity in DRB10 was biphasic. About half (53 to 56%) of this activity was inhibited by 90 microM DRB and thus showed a DRB sensitivity similar to the wild-type RNA polymerase II activity; the remaining DRB-sensitive RNA polymerase II activity was maximally inhibited by 300 microM DRB. These results indicated that there were two copies of the drbR locus (drb+ and drbR-10) in DRB10 and confirmed that the drbR-10 mutation was expressed codominantly. Somatic cell hybrids of DRB-resistant and alpha-amanitin-resistant cell lines grew in medium containing both DRB and alpha-amanitin, demonstrating that the drbR and amaR mutations were not in the same gene. Thus, the drbR mutations may define an additional component of the RNA polymerase II transcriptional complex in mammalian cells.

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Characterization of Chinese hamster ovary cell lines expressing human steroid 5 alpha-reductase isozymes

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)85349-8 ◽

1993 ◽

Vol 268 (23) ◽

pp. 17404-17412

Author(s):

A.E. Thigpen ◽

K.M. Cala ◽

D.W. Russell

Keyword(s):

Cell Lines ◽

Chinese Hamster Ovary Cell ◽

Chinese Hamster Ovary ◽

Chinese Hamster ◽

Ovary Cell

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Chinese hamster ovary cell line DXB-11: chromosomal instability and karyotype heterogeneity

Molecular Cytogenetics ◽

10.1186/s13039-021-00528-3 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Victoria I. Turilova ◽

Tatyana S. Goryachaya ◽

Tatiana K. Yakovleva

Keyword(s):

Cell Line ◽

Cell Lines ◽

Chinese Hamster Ovary Cell ◽

Chinese Hamster Ovary ◽

Chinese Hamster ◽

Chromosome 8 ◽

Ovary Cell ◽

Differential Staining ◽

Nucleolar Organizer Regions ◽

Karyotype Heterogeneity

Abstract Background Chinese hamster ovary cell lines, also known as CHO cells, represent a large family of related, yet quite different, cell lines which are metabolic mutants derived from the original cell line, CHO-ori. Dihydrofolate reductase-deficient DXB-11 cell line, one of the first CHO derivatives, serves as the host cell line for the production of therapeutic proteins. It is generally assumed that DXB-11 is identical to DUKX or CHO-DUK cell lines, but, to our knowledge, DXB-11 karyotype has not been described yet. Results Using differential staining approaches (G-, C-banding and Ag-staining), we presented DXB-11 karyotype and revealed that karyotypes of DXB-11 and CHO-DUK cells have a number of differences. Although the number of chromosomes is equal—20 in each cell line—DXB-11 has normal chromosomes of the 1st and 5th pairs as well as an intact chromosome 8. Besides, in DXB-11 line, chromosome der(Z9) includes the material of chromosomes X and 6, whereas in CHO-DUK it results from the translocation of chromosomes 1 and 6. Ag-positive nucleolar organizer regions were revealed in the long arms of chromosome del(4)(q11q12) and both chromosome 5 homologues, as well as in the short arms of chromosomes 8 and add(8)(q11). Only 19 from 112 (16.96%) DXB-11 cells display identical chromosome complement accepted as the main structural variant of karyotype. The karyotype heterogeneity of all the rest of cells (93, 83.04%) occurs due to clonal and nonclonal additional structural rearrangements of chromosomes. Estimation of the frequency of chromosome involvement in these rearrangements allowed us to reveal that chromosomes 9, der(X)t(X;3;4), del(2)(p21p23), del(2)(q11q22) /Z2, der(4) /Z7, add(6)(p11) /Z8 are the most stable, whereas mar2, probably der(10), is the most unstable chromosome. A comparative analysis of our own and literary data on CHO karyotypes allowed to designate conservative chromosomes, both normal and rearranged, that remain unchanged in different CHO cell lines, as well as variable chromosomes that determine the individuality of karyotypes of CHO derivatives. Conclusion DXB-11and CHO-DUK cell lines differ in karyotypes. The revealed differential instability of DXB-11 chromosomes is likely not incidental and results in karyotype heterogeneity of cell population.

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