Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli
AML1 and ETO genes are known partners in the t(8,21) translocation associated with the treatment-related leukaemias in the patients receiving chemotherapy with DNA-topoisomerase II (topo II) poisons. Aim. To determine whether the genes AML1 and ETO are in close proximity either permanently or temp...
Збережено в:
| Опубліковано в: : | Вiopolymers and Cell |
|---|---|
| Дата: | 2011 |
| Автори: | , , , , , , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Інститут молекулярної біології і генетики НАН України
2011
|
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/155653 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli / M.A. Rubtsov, S.I. Glukhov, J. Allinne, A. Pichugin, Y.S. Vassetzky, S.V. Razin, O.V. Iarovaia // Вiopolymers and Cell. — 2011. — Т. 27, № 5. — С. 398-403. — Бібліогр.: 24 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-155653 |
|---|---|
| record_format |
dspace |
| spelling |
Rubtsov, M.A. Glukhov, S.I. Allinne, J. Pichugin, A. Vassetzky, Y.S. Razin, S.V. Iarovaia, O.V. 2019-06-17T09:51:12Z 2019-06-17T09:51:12Z 2011 Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli / M.A. Rubtsov, S.I. Glukhov, J. Allinne, A. Pichugin, Y.S. Vassetzky, S.V. Razin, O.V. Iarovaia // Вiopolymers and Cell. — 2011. — Т. 27, № 5. — С. 398-403. — Бібліогр.: 24 назв. — англ. 0233-7657 DOI: http://dx.doi.org/10.7124/bc.00012D https://nasplib.isofts.kiev.ua/handle/123456789/155653 577.218 AML1 and ETO genes are known partners in the t(8,21) translocation associated with the treatment-related leukaemias in the patients receiving chemotherapy with DNA-topoisomerase II (topo II) poisons. Aim. To determine whether the genes AML1 and ETO are in close proximity either permanently or temporarily in the nucleus. Methods. 3D FISH. Results. We found that in 5 % of untreated cells, alleles of AML1 and ETO are in close proximity. This number increased two-fold in the cells treated with the topo II poison etoposide. Surprisingly, in more than 50 % of the cases observed, co-localization of the genes occurred at the nucleoli surface. We found also that the treatment of cells triggers preferential loading of RAD51 onto bcr of the AML1 and ETO genes. Conclusions. Our results suggest that the repair of DNA lesions introduced by topoisomerase II poisons may be mediated simultaneously by multiple mechanisms, which may be the cause of mistakes resulting in translocations. Keywords: DNA-topoisomerase II, nucleoli, Rad51, AML1, ETO. Гени AML1 і ETO відомі як партнери по транслокації t(8,21), асоційованої з розвитком вторинних лейкозів у пацієнтів, які піддавалися хіміотерапії із застосуванням інгібіторів топоізомерази II. Мета. Оцінити частоту взаємної колокалізаціїгенів AML1 і ETO у культурі лімфоїдних клітин людини. Методи. 3D FISH. Результати. У 5 % необроблених клітин лінії Jurkat алелі AML1 і ETO знаходяться в безпосередній близькості один від одного. У клітинах, оброблених інгібітором топоізомерази II етопозитом, частота подій колокалізації AML1 і ETO зростає в два рази. При цьому більш ніж у 50 % випадків колокалізація генів відбувається на поверхні ядерця. Показано, что обробка клітин етопозидом спричиняє посилення зв’язування білка RAD 51 з кластерами точок розриву (bcr) генів AML1 і ETO. Висновки. Репарація розривів ДНК, індукованих інгібіторами топоізомерази II, вірогідна за одночасної участі різних механізмів, що може бути причиною помилок, які викликають транслокації. Ключові слова: ДНК-топоізомераза II, ядерця, Rad51, AML1, ETO. Гены AML1 и ETO известны как партнеры по транслокации t(8,21), которая ассоциирована с развитием вторичных лейкозов у пациентов, подвергшихся химиотерапии с применением ингибиторов ДНК-топоизомеразы II. Цель. Оценить частоту взаимной колокализации генов AML1 и ETO в культуре лимфоидных клеток человека. Методы. 3D FISH. Результаты. В 5 % необработанных клеток линии Jurkat аллели AML1 и ETO находятся в непосредственной близости друг от друга. В клетках, обработанных ин - гибитором ДНК-топоизомеразы II этопозидом, частота событий колокализации AML1 и ETO увеличивается в два раза. При этом в более чем 50 % наблюдаемых случаев колокализация генов происходит на поверхности ядрышка. Показано, что обработка клеток этопозидом приводит к увеличению связывания белка RAD 51 с кластерами точек разрыва (bcr) генов AML1 и ETO. Выводы. Репарация разрывов ДНК, индуцированных ингибиторами ДНК-топоизомеразы II, вероятна при одновременном участии различных механизмов, что может являться причиной ошибок, приводящих к транслокациям. Ключевые слова: ДНК-топоизомераза II, ядрышка, Rad51, AML1, ETO. R. M. A.: MSERF (grants P1339, 16.740.11.0629), «Carl Zeiss», «Grant of the President of RF» (MK-222.2011.4), RFBR (grant 10- 04-00305-a). S. I. G.: MSERF (grant 14.740.11.1201). O. V. I. and S. V. R.: MCB grant, RFBR (grant 09-04-93105-CNRS_a). Y. S. V., J. A., A. P.: Fonda- tion de France, Canceropole de l’Ile de France, INC en Інститут молекулярної біології і генетики НАН України Вiopolymers and Cell Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli Обробка лімфоїдних клітин інгібітором топоізомерази II етопозитом спричиняє зростання колокалізації генів AML1 і ETO на поверхні ядерця Обработка лимфоидных клеток ингибитором топоизомеразы II этопозитом приводит к возрастанию колокализации генов AML1 и ETO на поверхности ядрышка Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli |
| spellingShingle |
Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli Rubtsov, M.A. Glukhov, S.I. Allinne, J. Pichugin, A. Vassetzky, Y.S. Razin, S.V. Iarovaia, O.V. |
| title_short |
Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli |
| title_full |
Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli |
| title_fullStr |
Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli |
| title_full_unstemmed |
Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli |
| title_sort |
treatment of lymphoid cells with the topoisomerase ii poison etoposide leads to an increased juxtaposition of aml1 and eto genes on the surface of nucleoli |
| author |
Rubtsov, M.A. Glukhov, S.I. Allinne, J. Pichugin, A. Vassetzky, Y.S. Razin, S.V. Iarovaia, O.V. |
| author_facet |
Rubtsov, M.A. Glukhov, S.I. Allinne, J. Pichugin, A. Vassetzky, Y.S. Razin, S.V. Iarovaia, O.V. |
| publishDate |
2011 |
| language |
English |
| container_title |
Вiopolymers and Cell |
| publisher |
Інститут молекулярної біології і генетики НАН України |
| format |
Article |
| title_alt |
Обробка лімфоїдних клітин інгібітором топоізомерази II етопозитом спричиняє зростання колокалізації генів AML1 і ETO на поверхні ядерця Обработка лимфоидных клеток ингибитором топоизомеразы II этопозитом приводит к возрастанию колокализации генов AML1 и ETO на поверхности ядрышка |
| description |
AML1 and ETO genes are known partners in the t(8,21) translocation associated with the treatment-related
leukaemias in the patients receiving chemotherapy with DNA-topoisomerase II (topo II) poisons. Aim. To
determine whether the genes AML1 and ETO are in close proximity either permanently or temporarily in the
nucleus. Methods. 3D FISH. Results. We found that in 5 % of untreated cells, alleles of AML1 and ETO are in
close proximity. This number increased two-fold in the cells treated with the topo II poison etoposide.
Surprisingly, in more than 50 % of the cases observed, co-localization of the genes occurred at the nucleoli
surface. We found also that the treatment of cells triggers preferential loading of RAD51 onto bcr of the AML1
and ETO genes. Conclusions. Our results suggest that the repair of DNA lesions introduced by topoisomerase II
poisons may be mediated simultaneously by multiple mechanisms, which may be the cause of mistakes resulting
in translocations.
Keywords: DNA-topoisomerase II, nucleoli, Rad51, AML1, ETO.
Гени AML1 і ETO відомі як партнери по транслокації t(8,21),
асоційованої з розвитком вторинних лейкозів у пацієнтів, які піддавалися хіміотерапії із застосуванням інгібіторів топоізомерази II. Мета. Оцінити частоту взаємної колокалізаціїгенів AML1 і
ETO у культурі лімфоїдних клітин людини. Методи. 3D FISH. Результати. У 5 % необроблених клітин лінії Jurkat алелі AML1 і
ETO знаходяться в безпосередній близькості один від одного. У
клітинах, оброблених інгібітором топоізомерази II етопозитом,
частота подій колокалізації AML1 і ETO зростає в два рази. При
цьому більш ніж у 50 % випадків колокалізація генів відбувається
на поверхні ядерця. Показано, что обробка клітин етопозидом
спричиняє посилення зв’язування білка RAD 51 з кластерами точок розриву (bcr) генів AML1 і ETO. Висновки. Репарація розривів
ДНК, індукованих інгібіторами топоізомерази II, вірогідна за одночасної участі різних механізмів, що може бути причиною помилок, які викликають транслокації.
Ключові слова: ДНК-топоізомераза II, ядерця, Rad51, AML1,
ETO.
Гены AML1 и ETO известны как партнеры по транслокации
t(8,21), которая ассоциирована с развитием вторичных лейкозов
у пациентов, подвергшихся химиотерапии с применением ингибиторов ДНК-топоизомеразы II. Цель. Оценить частоту взаимной
колокализации генов AML1 и ETO в культуре лимфоидных клеток
человека. Методы. 3D FISH. Результаты. В 5 % необработанных клеток линии Jurkat аллели AML1 и ETO находятся в непосредственной близости друг от друга. В клетках, обработанных ин -
гибитором ДНК-топоизомеразы II этопозидом, частота событий колокализации AML1 и ETO увеличивается в два раза. При
этом в более чем 50 % наблюдаемых случаев колокализация генов
происходит на поверхности ядрышка. Показано, что обработка
клеток этопозидом приводит к увеличению связывания белка
RAD 51 с кластерами точек разрыва (bcr) генов AML1 и ETO. Выводы. Репарация разрывов ДНК, индуцированных ингибиторами
ДНК-топоизомеразы II, вероятна при одновременном участии
различных механизмов, что может являться причиной ошибок,
приводящих к транслокациям.
Ключевые слова: ДНК-топоизомераза II, ядрышка, Rad51,
AML1, ETO.
|
| issn |
0233-7657 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/155653 |
| citation_txt |
Treatment of lymphoid cells with the topoisomerase II poison etoposide leads to an increased juxtaposition of AML1 and ETO genes on the surface of nucleoli / M.A. Rubtsov, S.I. Glukhov, J. Allinne, A. Pichugin, Y.S. Vassetzky, S.V. Razin, O.V. Iarovaia // Вiopolymers and Cell. — 2011. — Т. 27, № 5. — С. 398-403. — Бібліогр.: 24 назв. — англ. |
| work_keys_str_mv |
AT rubtsovma treatmentoflymphoidcellswiththetopoisomeraseiipoisonetoposideleadstoanincreasedjuxtapositionofaml1andetogenesonthesurfaceofnucleoli AT glukhovsi treatmentoflymphoidcellswiththetopoisomeraseiipoisonetoposideleadstoanincreasedjuxtapositionofaml1andetogenesonthesurfaceofnucleoli AT allinnej treatmentoflymphoidcellswiththetopoisomeraseiipoisonetoposideleadstoanincreasedjuxtapositionofaml1andetogenesonthesurfaceofnucleoli AT pichugina treatmentoflymphoidcellswiththetopoisomeraseiipoisonetoposideleadstoanincreasedjuxtapositionofaml1andetogenesonthesurfaceofnucleoli AT vassetzkyys treatmentoflymphoidcellswiththetopoisomeraseiipoisonetoposideleadstoanincreasedjuxtapositionofaml1andetogenesonthesurfaceofnucleoli AT razinsv treatmentoflymphoidcellswiththetopoisomeraseiipoisonetoposideleadstoanincreasedjuxtapositionofaml1andetogenesonthesurfaceofnucleoli AT iarovaiaov treatmentoflymphoidcellswiththetopoisomeraseiipoisonetoposideleadstoanincreasedjuxtapositionofaml1andetogenesonthesurfaceofnucleoli AT rubtsovma obrobkalímfoídnihklítiníngíbítoromtopoízomeraziiietopozitomspričinâêzrostannâkolokalízacíígenívaml1íetonapoverhníâdercâ AT glukhovsi obrobkalímfoídnihklítiníngíbítoromtopoízomeraziiietopozitomspričinâêzrostannâkolokalízacíígenívaml1íetonapoverhníâdercâ AT allinnej obrobkalímfoídnihklítiníngíbítoromtopoízomeraziiietopozitomspričinâêzrostannâkolokalízacíígenívaml1íetonapoverhníâdercâ AT pichugina obrobkalímfoídnihklítiníngíbítoromtopoízomeraziiietopozitomspričinâêzrostannâkolokalízacíígenívaml1íetonapoverhníâdercâ AT vassetzkyys obrobkalímfoídnihklítiníngíbítoromtopoízomeraziiietopozitomspričinâêzrostannâkolokalízacíígenívaml1íetonapoverhníâdercâ AT razinsv obrobkalímfoídnihklítiníngíbítoromtopoízomeraziiietopozitomspričinâêzrostannâkolokalízacíígenívaml1íetonapoverhníâdercâ AT iarovaiaov obrobkalímfoídnihklítiníngíbítoromtopoízomeraziiietopozitomspričinâêzrostannâkolokalízacíígenívaml1íetonapoverhníâdercâ AT rubtsovma obrabotkalimfoidnyhkletokingibitoromtopoizomerazyiiétopozitomprivoditkvozrastaniûkolokalizaciigenovaml1ietonapoverhnostiâdryška AT glukhovsi obrabotkalimfoidnyhkletokingibitoromtopoizomerazyiiétopozitomprivoditkvozrastaniûkolokalizaciigenovaml1ietonapoverhnostiâdryška AT allinnej obrabotkalimfoidnyhkletokingibitoromtopoizomerazyiiétopozitomprivoditkvozrastaniûkolokalizaciigenovaml1ietonapoverhnostiâdryška AT pichugina obrabotkalimfoidnyhkletokingibitoromtopoizomerazyiiétopozitomprivoditkvozrastaniûkolokalizaciigenovaml1ietonapoverhnostiâdryška AT vassetzkyys obrabotkalimfoidnyhkletokingibitoromtopoizomerazyiiétopozitomprivoditkvozrastaniûkolokalizaciigenovaml1ietonapoverhnostiâdryška AT razinsv obrabotkalimfoidnyhkletokingibitoromtopoizomerazyiiétopozitomprivoditkvozrastaniûkolokalizaciigenovaml1ietonapoverhnostiâdryška AT iarovaiaov obrabotkalimfoidnyhkletokingibitoromtopoizomerazyiiétopozitomprivoditkvozrastaniûkolokalizaciigenovaml1ietonapoverhnostiâdryška |
| first_indexed |
2025-11-26T22:59:20Z |
| last_indexed |
2025-11-26T22:59:20Z |
| _version_ |
1850779370879188992 |
| fulltext |
Treatment of lymphoid cells with the topoisomerase II
poison etoposide leads to an increased juxtaposition of
AML1 and ETO genes on the surface of nucleoli
M. A. Rubtsov1, S. I. Glukhov1, J. Allinne3, A. Pichugin3, Y. S. Vassetzky3,
S. V. Razin1, 2, O. V. Iarovaia2
1Moscow State University
1/12, Leninskie Gory, Moscow, Russian Federation, 119899
2Institute of Gene Biology, RAS
34/5, Vavilov Str., Moscow, Russia Federation, 119334
3CNRS UMR 8126, Univ. Paris-Sud 11, IGR
39, Camille-Desmoulins Str., 94805 Villejuif, France
ma_rubtsov@mail.ru
AML1 and ETO genes are known partners in the t(8,21) translocation associated with the treatment-related
leukaemias in the patients receiving chemotherapy with DNA-topoisomerase II (topo II) poisons. Aim. To
determine whether the genes AML1 and ETO are in close proximity either permanently or temporarily in the
nucleus. Methods. 3D FISH. Results. We found that in 5 % of untreated cells, alleles of AML1 and ETO are in
close proximity. This number increased two-fold in the cells treated with the topo II poison etoposide.
Surprisingly, in more than 50 % of the cases observed, co-localization of the genes occurred at the nucleoli
surface. We found also that the treatment of cells triggers preferential loading of RAD51 onto bcr of the AML1
and ETO genes. Conclusions. Our results suggest that the repair of DNA lesions introduced by topoisomerase II
poisons may be mediated simultaneously by multiple mechanisms, which may be the cause of mistakes resulting
in translocations.
Keywords: DNA-topoisomerase II, nucleoli, Rad51, AML1, ETO.
Introduction. Chromosomal translocations are a cha-
racteristic feature of leukaemia, and they are the under-
lying cause in a number of cases. Translocations are a
consequence of the faulty repair of double-stranded
DNA breaks (DSBs) originating in the course of vari-
ous physiological and pathological processes. As a ru-
le, leukaemogenic translocations affect key regulators
of hemopoiesis and result in the formation of chimeric
genes. In some cases, oncogenesis is caused by the pro-
ducts of these particular chimeric genes [1].
For the translocation between gene partners,
certain conditions must be satisfied. These conditions
concern both the localization of recombination partners
in the nuclear space and the mode of action of DSB re-
pair mechanisms. First of all, the direct contact bet-
ween recombination partners should be possible and
even probable. To fulfil this condition, the recombina-
tion partners should be located close to each other in
the nuclear space either permanently or for a conside-
rable time interval. The latter may happen when the ge-
nes are temporarily attracted to the same nuclear com-
partment, such as a common transcription factory [2],
PML bodies [3], or a hormone receptor [4]. Localiza-
tion of a pair of genes in the vicinity of the nucleolus
may increase the probability of illegitimate recom-
bination between these genes. The nucleolus appears to
398
ISSN 0233–7657. Biopolymers and Cell. 2011. Vol. 27. N 5. P. 398–403
Institute of Molecular Biology and Genetics, NAS of Ukraine, 2011
399
TREATMENT OF LYMPHOID CELLS WITH THE TOPOISOMERASE II POISON ETOPOSIDE
be a storage place for many proteins that participate in
DNA repair [5, 6]; moreover, the process of sliding
along the nucleolus surface may help the heterologous
DNA ends, generated as a result of double-strand bre-
aks, to contact one another. Alternatively, rapproche-
ment between distantly located genes could be a result
of fundamental changes in nuclear architecture that
may occur under some special conditions. However,
simple rapprochement of genes in the nuclear space do-
es not result in translocation. The presence of a DSB
and physical contact between broken DNA ends appe-
ars to be absolutely necessary. Furthermore, the trans-
location partners should be damaged simultaneously
or an unrepaired DSB should persist in the nucleus for
a significant period of time. This increases the proba-
bility of contact between heterologous DNA ends.
A DNA DSB may be repaired by two different me-
chanisms [7]. In the post-replication stage, the most ef-
fective mechanism is the homologous recombination
(HR). HR is normally considered to be an error-free
system because the undamaged sister chromatid pro-
vides a perfect donor of homology [8]. In contrast to
HR, the non-homologous end joining (NHEJ) system
mediates direct ligation of DNA ends originating as a
result of DSBs without looking for a homology donor.
This system, which appears to be the main system of
DSB repair in higher eukaryotes, is an error-prone sys-
tem [9]. DSB repair by NHEJ often leads both to insig-
nificant «misprints» in the immediate proximity of the
breakpoint and to translocations of extended DNA re-
gions due to the joining of «wrong» DNA ends [10].
Rapid disconnection of damaged DNA ends resulting
in their separation within the nuclear space appears to
be a condition for the subsequent joining of incorrect
ends and therefore for a translocation event.
The translocation t(8,21) between loci containing
the genes AML1 and ETO is associated with the deve-
lopment of acute myeloid leukaemia [11]. That is es-
pecially characteristic for secondary leukaemias (t-
ANLL, treatment-related leukaemia) originating as a
consequence of anti-tumour chemotherapy with inhi-
bitors of topo II. DSBs originating under the action of
topo II poisons are distributed non-randomly in the se-
quences of translocation partners, and are grouped into
so-called breakpoint cluster regions – bcr [12]. The
translocations leading to the formation of chimeric ge-
nes, the products of which cause malignant transfor-
mation and t-ANNL, occur predominantly between bcr
of different genes [13].
The aim of the present work was to determine whe-
ther the genes AML1 and ETO are in close proximity
either permanently or temporarily in the nucleus. To
this end, we assessed the degree of mutual localization
between these genes and their proximity to the nucleo-
lus in both normal cells and cells treated with the topo
II poison etoposide. In addition, we studied the distri-
bution of repair proteins that may help to establish and
maintain contact between heterologous DNA ends and
thereby promote the recombination between AML1
and ETO.
Materials and methods. Cell culture and slide pre-
paration. A culture of Jurkat cells was received from
the Institute of Medical Genetics RAMS. The cells we-
re grown in RPMI with 10 % FBS at 37 °C in a 5 %
CO2. In the experiments with etoposide, the Jurkat cells
were incubated for 1.5 h in the presence of 0.17 mM
etoposide. Cells were attached to slides using Cell-
Tak™ («BD Bioscience»). The slides were incubated
for 1 min in 0.3 × PBS, fixed immediately in 4 % para-
formaldehyde in 0.3 × PBS (pH 7.4) for 10 min at RT
and washed in 1 × PBS. The cells were permeabilized at
RT in 0.5 % (w/v) Triton X-100 in 1 × PBS for 10 min,
incubated for 1 h in 20 % (v/v) glycerol in 1 × PBS
followed by freezing-thawing in liquid nitrogen and
washing in 1 × PBS. Cells were treated with 0.1 M HCl
for 20 min at RT, washed in 1 × PBS, treated with
RNAseA in 2 × SSC (200 µg/ml) for 30 min at 37 oC,
washed with 2 × SSC and equilibrated in 50 % (v/v)
deionized formamide in 2 × SSC for at least 2 h. The
prepared slides were used immediately or stored at 4 oC
for up to two weeks.
Visualization of the AML1 and ETO genes and nuc-
leoli via 3D fluorescence in situ hybridization (3D
FISH). The DNA in cells fixed on microscope slides
was denatured in 70 % (v/v) deionized formamide in 2 ×
× SSC for 16 min at 75°C. One microliter of Vysis® LSI®
AML1/ETO Dual Color, Dual Fusion Translocation
Probe («Abbott Lab.») was mixed with 4 µl of Vysis®
hybridization buffer, and the mixture was incubated
for 5 min at 74 oC. Then the mixture was applied to the
hot slides, and hybridization was carried out overnight
at 37 oC (in a humid chamber).Then the samples were
washed for 30 min in 50 % (v/v) formamide in 2 × SSC
at 52 oC, for 10 min in 0.2 × SSC at 52 oC, for 5 min in
0.1 % (v/v) NP-40 in 2 × SSC at 52 oC and finally for
3 min in 2 × SSC at RT.
To visualize nucleoli, mouse monoclonal anti-nuc-
leophosmin antibody («Chemicon Int.») was used with
subsequent signal acquisition via an Alexa 647-con-
jugated chicken anti-mouse antibody («Mol. Probes»).
In all cases, DNA was counterstained with DAPI.
Immunostaining. Cells were precipitated to micro-
scope slides using cytospin (0.5 million cells per slide),
fixed (1 % paraformaldehyde, 2.5 % Triton-X100,
10 mM Pipes (pH 6.9), 100 mM NaCl, 1.5 mM MgCl2,
300 mM Sucrose) for 20 min at RT and washed in 1 ×
× PBS. Then treated with blocking reagent solution
(BR, «Roche») for 1 h at RT and incubated with prima-
ry antibody (dilution 1:50 (v/v) in BR) overnight at
4 oC. Then, the preparations were washed in washing
solution (1 × PBS, 0.25 % BSA, 0.05 % Tween 20), in-
cubated with secondary antibody (dilution 1:200 (v/v)
in BR) for 30 min at RT, washed in washing solution,
rinsed with 1 × PBS and counterstained with DAPI. The
antibodies used: mouse monoclonal anti-nucleophos-
min antibody («Chemicon Int.»), mouse monoclonal an-
ti-fibrillarin antibody (Abcam) and Alexa 488-conju-
gated rabbit anti-mouse antibody («Mol. Probes»).
Chromatin immunoprecipitation and real-time
PCR. Chromatin immunoprecipitation was performed
as described previously [14]. Rabbit anti-nucleolin
antibody («Sigma») and rabbit anti-Rad51 antibody
(«Sigma») were used. The amount of DNA bound to
nucleolin or to Rad51 before and after etoposide treat-
ment was determined by real-time PCR with the follo-
wing primers and TaqMan probes (FAM – a fluores-
cent dye at the 5' end of samples; BHQ-1 – fluorescence
quencher in the probe on T):
AML1_BCR3_direct: 5'CCAGCCCACAACAGG
AGAC3'; AML1_BCR3_reverse: 5'ATACTTCTGAG
GGAAAGGGATG3;
AML1_exon_5_direct: 5'TTCCTGCCTTCATTC
TCTGC3; AML1_exon_5_reverse: 5'TGTCCCCAAA
AGCCAAGAT3';
ETO_BCR2_direct: 5'TCTGATAGTGCCAATG
CCTTTA3'; ETO_BCR2_reverse: 5'CTTGCTAGTG
CCTATGTAGGAATCT3';
ETO_exon_1a_direct: 5'GCATCCTTGAATCCA
GCGTA3'; ETO_exon_1a_reverse: 5'CCTCCACATT
TCTGCTCCAA3';
AML1_BCR3: 5'(FAM)CGCAAACAGCCT (BH
Q-1)GAGTCACGCA3'; AML1_exon_5: 5'(FAM)AA
GAGGAAAGT(BHQ-1)GAGGTTCAGCAAGGC3';
ETO_BCR2: 5'(FAM)TTCATTTCCACCAACT
(BHQ-1)TATTTTCAACGTCT3'; ETO_exon_1a: 5'(F
AM)TGGAATGAGT(BHQ-1)GGCAGCAGAGAGG
A3'.
Amplification was performed in 20 µl of PCR buf-
fer (50 mM Tris (pH 8.6), 50 mM KCl, 1.5 mM MgCl2,
and 0.1 % Tween 20) containing test DNA, 0.5 µM
each primer, 0.25 µM TaqMan probe, 0.2 mM each
dNTP and 0.75 units of hot-start Taq DNA polymerase
(«Sibenzyme»). Conditions: at 94 oC for 5 min (one
cycle); and 94 oC for 15 s, 60 oC for 60 s, fluorescence
detection (49 cycles). The results were analysed using
Opticon Monitor 3.1 («Bio-Rad Lab»).
Results and discussion. Analysis of the mutual lo-
calization of the AML1 and ETO genes in the nucleus.
We first studied the mutual localization of the AML1
and ETO genes in nuclear space in cells under normal
conditions and in cells treated with the topo II poison
etoposide. The 3D immuno-FISH technique was emplo-
yed in these experiments using commercially available
fluorescent probes, regularly used in clinical practice
for analysis and diagnosis of t(8;21) translocations in
leukaemia. We were particularly interested in enume-
rating the cases where AML1 and ETO loci are in con-
tact with each other. In addition, the relative positions
of these loci with respect to the nucleolus were re-
gistered.
The FISH results were analysed using an LSM 510
(«Carl Zeiss, Inc.») confocal microscope. Confocal sec-
tions of the cells under study were processed using
ZEN 2009 LE software («Carl Zeiss, Inc.») to make 3D
reconstructions. Typical examples of the 3D recon-
structions showing various juxtapositions of the AML1
and ETO genes together with the nucleolus are presen-
ted in Fig. 1, A–C (see inset). In Fig. 1, A, the situation
is shown where one of the AML1 alleles is located very
close to one of the ETO alleles (the signals touch each
other but do not overlap). In Fig. 1, B, the situation is
shown where AML1 and ETO alleles touch each other
and the surface of the nucleolus. Finally, in Fig. 1, C,
the situation is shown where all the AML1 and ETO al-
leles are located at a considerable distance from one
another. The results of an analysis are presented in a
table (Fig. 1, D, see inset).
To characterize the mutual localization of these ge-
nes, we used the open-source software NEMO (an up-
graded version of the well known ImageJ plug-in
«Smart 3D-FISH»). NEMO is designed to detect auto-
matically various objects (e. g., spots, genes, nuclei or
chromosomal regions) located in individual cells and to
analyse the distances between these objects [15]. We
defined hybridization signals as being in close vicinity
(or in contact as shown in Fig. 1, A1) in cases where the
400
RUBTSOV M. A. ET AL.
ISSN 0233–7657. Biopolymers and Cell. 2011. Vol. 27. N 5
Fig. 1. Three distinct juxtapositions ob-
served during mutual localization ana-
lysis of the genes AML1 and ETO and
nucleoli inside Jurkat cell nuclei. Blue –
nucleoli immunostained for nucleophos-
min (B23), green and red – hybridizati-
on signals corresponding to AML1 and
ETO genes, respectively. Bar: 5 µm. For
each case, three projections of the 3D
model are shown. A – AML1 and ETO
are in contact with each other but not
with a nucleolus; B – AML1 and ETO
are in contact with each other and with a
nucleolus (A1, B1 – scaled-up excisi-
ons); C – AML1 and ETO are distant
from each other; D – results of signal
counting. In the line designated «Etopo-
side» the results of counting signals in
etoposide-treated cells are presented. Gi-
ven results represent an aggregated va-
lues obtained in three independent ex-
periments having total samplings indica-
ted in «Number of signals» column. All
the values expressed as a percentage pos-
sess standard error (SE) of less than
0.85 %
Phase contrast B 23 Merge
Phase contrast Fibrillarin Merge
A
B
Fig. 2. Immunostaining of Jurkat
cells using antibodies against
nucleolin (A) and fibrillarin (B)
is shown. Nucleolar extrusion
from the nuclei of cells treated
with etoposide (Etoposide) is ap-
parent. Staining of nucleoli with
the same antibodies in non-
treated cells (Control) is shown
for a comparison. Bar: 5 µm
Figures to article by M. A. Rubtsov et al.
estimated NEMO «colocalization percentage» (which
the authors define as «the percentage of the smallest ob-
ject into the biggest object colocalization») was more
than 1 %. To this end it should be mentioned that we ha-
ve never observed significant overlapping of the AML1
and ETO signals. In our case it has never exceeded 5 %.
In spite of its peri-telomeric position in chromosome
21, at least one AML1 signal was located at the surface
of one of the nucleoli in 55 % of cells. An analysis of
the spatial distribution showed that almost 5 % of all
the AML1 and ETO hybridization signals were located
in close proximity (Fig. 1, A1). Furthermore, almost
half of the juxtaposed AML1 and ETO signals were
located at the border of the nucleolus (Fig. 1, B1).
We demonstrated previously that treatment of pri-
mary human fibroblasts with etoposide causes reloca-
tion of the ETO gene in nuclear space [16]. As a result
of this relocation, the average distance between AML1
and ETO alleles decreased. However, in this previous
work, we did not observe the cases in which AML1 and
ETO alleles were in direct contact. Perhaps this does
not happen in primary fibroblasts. In the present work,
we performed the same analysis using human lympho-
id cells (Jurkat). Remarkable rapprochement of the
AML1 and ETO genes occurred after treatment of the
cells with etoposide. The percentage of juxtaposed
AML1 and ETO signals doubled as a result of etoposide
treatment, reaching almost 10 % of the total number of
calculated signals (Fig. 1, D). The number of juxtapo-
sed AML1 and ETO alleles located on the surface of nuc-
leoli increased approximately three-fold (Fig. 1, D).
Role of the nucleolus in the rapprochement of the
AML1 and ETO genes induced by etoposide. In hu-
mans, AML1 is located on chromosome 21, which har-
bours a nucleolar organizer. Thus, the relocation of
AML1 in nuclear space may be a consequence of nucleo-
lar relocation. In this regard, it may be of importance
that treating cells with etoposide causes the extrusion
of the nucleolus beyond the border of the nucleus, as
shown in Fig. 2 (see inset). We treated Jurkat cells with
etoposide and then fixed and stained them with anti-
bodies against nucleophosmin and fibrillarin. This reve-
aled that nucleoli are extruded from the cells treated
with etoposide. The nucleolar extrusion is likely to oc-
cur when the apoptotic program is triggered. However,
reversion is still likely to be possible during the initial
steps of this program. To this end, it should be noted
that under conditions of cell treatment used in our expe-
riments a complete extrusion of nucleoli was observed
only in a very small portion of cells. In control expe-
riment, when after 1.5 h treatments with etoposide the
cells were placed in a fresh medium without etoposide,
the population continued to grow (not shown). None-
theless, the movement of nucleoli toward the nuclear pe-
riphery may constitute a driving force for the repositio-
ning of AML1 from the central to the peripheral part of
the nucleus. It has been shown before that treatment of
cells with other cytotoxic agents also causes nucleolar
extrusion without separation of the nucleolus from the
surrounding chromatin layer [17]. Thus, under certain
conditions, the nucleolus may serve as a «carrier» that
conveys proximal genes (including AML1) to the peri-
phery, where ETO is predominantly located.
One of the major nucleolar proteins is nucleolin. In
addition to participating in the biogenesis of riboso-
mes, nucleolin performs many other functions, being
involved in the regulation of cell growth and prolife-
ration, stress responses, DNA replication and repair
[18]. Taking into account the fact that AML1 and ETO
alleles were frequently observed to be in close proximi-
ty on the nucleoli, we looked for association of nucleo-
lin with the bcr of AML1 and ETO.
Using the chromatin IP approach, we found that
nucleolin interacts not only with the bcr of both AML1
and ETO but also with other regions of these genes.
Moreover, the degree of association between nucleolin
and both AML1 and ETO increased two-fold in respon-
se to etoposide treatment (data not shown). One can
speculate that this increased association of both ETO
and AML1 with nucleolin after etoposide treatment con-
tributes to their retention at the border of the nucleolus
and increases the probability that these heterologous
DNA ends would interact.
Direct participation of nucleolin in the repair of
DSBs (including those introduced by topo II) should
not be ruled out. Nucleolin interacts with a variety of
proteins that participate in the repair, replication and re-
combination of DNA, and it possesses helicase, strand-
annealing and strand-pairing activities [18]. It has been
previously shown that electroporation of antibodies
against nucleolin into cells increases their sensitivity to
the topoisomerase poison amsacrine [19].
Increased association of RAD51 with both AML1
and ETO in cells treated with etoposide. We have pre-
viously demonstrated that stalled topo II complexes are
recognized by cells as DSB and are repaired via NHEJ
[20]. Moreover, we have found that treating cells with
etoposide caused the proteins mediating NHEJ to
401
TREATMENT OF LYMPHOID CELLS WITH THE TOPOISOMERASE II POISON ETOPOSIDE
accumulate at the bcr of both AML1 and ETO [21].
DSB repair by NHEJ is accompanied by numerous mis-
takes that may be a cause of translocations. However,
the participation of the HR pathway in the repair of
DNA DSB caused by inhibitors of topo II ligation
should not be ruled out. HR mechanisms can facilitate
replication fork passage of the damaged region and the
resumption of normal replication [22]. One of the key
players in the HR repair system is RAD51 [23]. RAD51
forms a complex with DNA close to breakpoints [24].
We analysed the level of association between
RAD51 and the bcr of both AML1 and ETO in control
cells and cells treated with etoposide. The results
obtained (Fig. 3) allowed us to conclude that treatment
of cells with etoposide results in a significant (up to 100
fold) increase in the levels of association between
RAD51 and all the loci, and this effect was especially
prominent at the bcr. Thus, HR may participate in the
repair of topo II induced DSB. In this regard, it may be
of interest that the bcr of AML1 and ETO possess
relatively long (up to 17 bp) regions of homology that
may be «considered» as homology donors by the HR re-
pair mechanism, resulting in the joining of heterolo-
gous chromosomal fragments and the generation of a
leukaemogenic chimeric gene.
Whatever the reason for the recruitment of RAD51
to bcr in the cells treated with topo II poisons, this re-
cruitment is likely to destabilize these regions in con-
junction with the topo II-mediated DSB and collapsed
replication forks. Consequently, the mobilization of
broken DNA ends is likely to occur there. Indeed, the
normal function of RAD51 is to form a filament with
single-stranded DNA and to invade undamaged homo-
logous sister chromatids. In the conditions when recom-
bination partners are in close proximity, their simulta-
neous damaging and simultaneous destabilization of
breaks may increase the probability of translocations
between them. A search for the homologous sequences
carried out by RAD51 in complex with DNA may faci-
litate the rapprochement of heterologous DNA ends,
and the presence of microhomologies increases the pro-
bability of translocations.
The observations presented allow one to propose a
prospective way to prevent leukaemogenic translocati-
ons, in particular by using chemotherapeutic agents
which does not lead to significant changes in nuclear archi-
tecture. In case of topo II poisons, it should be those that
do not cause accumulation of topo II stalled complexes.
Acknowledgments. R. M. A.: MSERF (grants
P1339, 16.740.11.0629), «Carl Zeiss», «Grant of the
President of RF» (MK-222.2011.4), RFBR (grant 10-
04-00305-a). S. I. G.: MSERF (grant 14.740.11.1201).
O. V. I. and S. V. R.: MCB grant, RFBR (grant
09-04-93105-CNRS_a). Y. S. V., J. A., A. P.: Fonda-
tion de France, Canceropole de l’Ile de France, INCa.
М. А. Руб цов, С. І. Глу хов, Ж. Аллінне, А. Пічугін,
Є. С. Ва сець кий, С. В. Разін, О. В. Яро ва
Оброб ка лімфої дних клітин інгібіто ром топоізо ме ра зи II
ето по зи том спри чи няє зрос тан ня ко ло калізації генів
AML1 і ETO на по верхні ядер ця
Ре зю ме
Гени AML1 і ETO відомі як пар тне ри по транс ло кації t(8,21),
асоційо ва ної з роз вит ком вто рин них лей козів у пацієнтів, які під-
да ва ли ся хіміот е рапії із за сто су ван ням інгібіторів топоізо ме ра -
зи II. Мета. Оцінити час то ту взаємної ко ло калізації генів AML1 і
ETO у куль турі лімфої дних клітин лю ди ни. Ме то ди. 3D FISH. Ре -
зуль та ти. У 5 % не об роб ле них клітин лінії Jurkat алелі AML1 і
ETO зна хо дять ся в без по се редній близь кості один від од но го. У
кліти нах, об роб ле них інгібіто ром топоізо ме ра зи II ето по зи том,
час то та подій ко ло калізації AML1 і ETO зрос тає в два рази. При
цьо му більш ніж у 50 % ви падків ко ло калізація генів відбу вається
на по верхні ядер ця. По ка за но, что об роб ка клітин ето по зи дом
спри чи няє по си лен ня зв’я зу ван ня білка RAD 51 з клас те ра ми то -
чок роз ри ву (bcr) генів AML1 і ETO. Вис нов ки. Ре па рація роз ривів
ДНК, інду ко ва них інгібіто ра ми топоізо ме ра зи II, вірогідна за од -
но час ної участі різних ме ханізмів, що може бути при чи ною по -
ми лок, які вик ли ка ють транс ло кації.
Клю чові сло ва: ДНК-топоізо ме ра за II, ядер ця, Rad51, AML1,
ETO.
402
RUBTSOV M. A. ET AL.
0
2 0
4 0
6 0
8 0
1 0 0
1 2 3 4
BCR3 BCR2 BCR1 Exon 5
Exon 1 a BCR3 BCR2
25 kbp
10 kbp
AML1
ETO
A
B
Fig. 3. Increased association of RAD51 with AML1 and ETO after treat-
ment of cells with etoposide: A – map of the genomic regions under stu-
dy showing positions of test amplicons (vertical lines with asterisks);
B – a diagram illustrating the results of ChIP with antibodies against
Rad51 (fold-enrichment of DNA fragments containing test-amplicons
in immunoprecipitated material obtained from cells treated with etopo-
side relative to that in material from untrea ted cells). 1-AML1-BCR3:
2-AMl1-exon5 3-ETO-BCR2 4-ETO-exon1a. Bars represent the stan-
dard deviation
М. А. Руб цов, С. И. Глу хов, Ж. Аллинне, А. Пи чу гин,
Е. С. Ва сец кий, С. В. Ра зин, О. В. Яро вая
Обра бот ка лим фо ид ных кле ток ин ги би то ром то по и зо ме ра зы II
это по зи том при во дит к воз рас та нию ко ло ка ли за ции ге нов AML1
и ETO на по вер хнос ти яд рыш ка
Ре зю ме
Гены AML1 и ETO из вес тны как пар тне ры по транс ло ка ции
t(8,21), ко то рая ас со ци и ро ва на с раз ви ти ем вто рич ных лей ко зов
у па ци ен тов, под вер гших ся хи ми о те ра пии с при ме не ни ем ин ги би -
то ров ДНК-то по и зо ме ра зы II. Цель. Оце нить час то ту вза им ной
ко ло ка ли за ции ге нов AML1 и ETO в куль ту ре лим фо ид ных кле ток
че ло ве ка. Ме то ды. 3D FISH. Ре зуль та ты. В 5 % не об ра бо тан-
ных кле ток ли нии Jurkat ал ле ли AML1 и ETO на хо дят ся в не пос ред-
ствен ной бли зос ти друг от дру га. В клет ках, об ра бо тан ных ин -
ги би то ром ДНК-то по и зо ме ра зы II это по зи дом, час то та со бы -
тий ко ло ка ли за ции AML1 и ETO уве ли чи ва ет ся в два раза. При
этом в бо лее чем 50 % на блю да е мых слу ча ев ко ло ка ли за ция ге нов
про ис хо дит на по вер хнос ти яд рыш ка. По ка за но, что об ра бот ка
кле ток это по зи дом при во дит к уве ли че нию свя зы ва ния бел ка
RAD 51 с клас те ра ми то чек раз ры ва (bcr) ге нов AML1 и ETO. Вы -
во ды. Ре па ра ция раз ры вов ДНК, ин ду ци ро ван ных ин ги би то ра ми
ДНК-то по и зо ме ра зы II, ве ро ят на при од но вре мен ном учас тии
раз лич ных ме ха низ мов, что мо жет яв лять ся при чи ной оши бок,
при во дя щих к транс ло ка ци ям.
Клю че вые сло ва: ДНК-то по и зо ме ра за II, яд рыш ка, Rad51,
AML1, ETO.
REFERENCES
1. Gollin S. M. Mechanisms leading to nonrandom, nonhomologo-
us chromosomal translocations in leukemia // Semin. Cancer.
Biol.–2007.–17, N 1.–P. 74–79.
2. Osborne C. S., Chakalova L., Mitchell J. A., Horton A., Wood A.
L., Bolland D. J., Corcoran A. E., Fraser P. Myc dynamically and
preferentially relocates to a transcription factory occupied by Igh
// PLoS Biol.–2007.–5, N 8.–e192.–P. 1763–1772.
3. Lallemand-Breitenbach V., de The H. PML nuclear bodies // Cold
Spring Harb. Perspect. Biol.–2010.–2, N 5.–a000661.–P. 1–17.
4. Lin C., Yang L., Tanasa B., Hutt K., Ju B. G., Ohgi K., Zhang J.,
Rose D. W., Fu X. D., Glass C. K., Rosenfeld M. G. Nuclear re-
ceptor-induced chromosomal proximity and DNA breaks under-
lie specific translocations in cancer // Cell.–2009.–139, N 6.–
P. 1069–1083.
5. Boisvert F. M., van Koningsbruggen S., Navascues J., Lamond
A. I. The multifunctional nucleolus // Nat. Rev. Mol. Cell Biol.–
2007.–8, N 7.–P. 574–585.
6. Boulon S., Westman B. J., Hutten S., Boisvert F. M., Lamond A.
I. The nucleolus under stress // Mol. Cell.–2010.–40, N 2.–
P. 216–227.
7. Shrivastav M., De Haro L. P., Nickoloff J. A. Regulation of DNA
double-strand break repair pathway choice // Cell Res.–2008.–18,
N 1.–P. 134–147.
8. Bernstein K. A., Rothstein R. At loose ends: resecting a double-
strand break // Cell.–2009.–137, N 5.–P. 807–810.
9. Lieber M. R., Gu J., Lu H., Shimazaki N., Tsai A. G. Nonhomolo-
gous DNA end joining (NHEJ) and chromosomal translocations
in humans // Subcell. Biochem.–2010.–50.–P. 279–296.
10. Heisig P. Type II topoisomerases–inhibitors, repair mechanisms
and mutations // Mutagenesis.–2009.–24, N 6.–P. 465–469.
11. Nucifora G., Rowley J. D. AML1 and the 8;21 and 3;21 translo-
cations in acute and chronic myeloid leukemia // Blood.–1995.–
86, N 1.–P. 1–4.
12. Miyoshi H., Shimizu K., Kozu T., Maseki N., Kaneko Y., Ohki M.
t(8;21) breakpoints on chromosome 21 in acute myeloid leuke-
mia are clustered within a limited region of a single gene, AML1
// Proc. Natl Acad. Sci. USA.–1991.–88, N 23.–P. 10431–14034.
13. Tighe J. E., Daga A., Calabi F. Translocation breakpoints are
clustered on both chromosome 8 and chromosome 21 in the t(8;
21) of acute myeloid leukemia // Blood.–1993.–81, N 3.–P. 592–
596.
14. Medeiros R. B., Papenfuss K. J., Hoium B., Coley K., Jadrich J.,
Goh S. K., Elayaperumal A., Herrera J. E., Resnik E., Ni H. T.
Novel sequential ChIP and simplified basic ChIP protocols for
promoter co-occupancy and target gene identification in human
embryonic stem cells BMC // Biotechnol.–2009.–9.–P. 59.
15. Iannuccelli E., Mompart F., Gellin J., Lahbib-Mansais Y., Yerle
M., Boudier T. NEMO: a tool for analyzing gene and chromoso-
me territory distributions from 3D-FISH experiments // Bioinfor-
matics.–2010.–26, N 5.–P. 696–697.
16. Rubtsov M. A., Terekhov S. M., Razin S. V., Iarovaia O. V. Repo-
sitioning of ETO gene in cells treated with VP-16, an inhibitor
of DNA-topoisomerase II // J. Cell Biochem.–2008.–104, N 2.–
P. 692–699
17. Pellicciari C., Bottone M. G., Scovassi A. I., Martin T. E., Big-
giogera M. Rearrangement of nuclear ribonucleoproteins and ex-
trusion of nucleolus-like bodies during apoptosis induced by hy-
pertonic stress // Eur. J. Histochem.–2000.–44, N 3.–P. 247–254.
18. Mongelard F., Bouvet P. Nucleolin: a multiFACeTed protein //
Trends Cell Biol.–2007.–17, N 2.–P. 80–86.
19. De A., Donahue S. L., Tabah A., Castro N. E., Mraz N., Cruise J.
L., Campbell C. A novel interaction [corrected] of nucleolin with
Rad51 // Biochem. Biophys. Res. Commun.–2006.–344, N 1.–
P. 206–213.
20. Kantidze O. L., Iarovaia O. V., Razin S. V. Assembly of nuclear
matrix-bound protein complexes involved in non-homologous
end joining is induced by inhibition of DNA topoisomerase II //
J. Cell Physiol.–2006.–207, N 3.–P. 660–667.
21. Kantidze O. L., Iarovaia O. V., Philonenko E. S., Yakutenko I. I.,
Razin S. V. Unusual compartmentalization of CTCF and other
transcription factors in the course of terminal erythroid dif-
ferentiation // Biochim. Biophys. Acta.–2007.–1773, N 6.–
P. 924–933.
22. Lambert S., Mizuno K., Blaisonneau J., Martineau S., Chanet
R., Freon K., Murray J. M., Carr A. M., Baldacci G. Homologo-
us recombination restarts blocked replication forks at the expen-
se of genome rearrangements by template exchange // Mol. Cell.–
2010.–39, N 3.–P. 346–359.
23. Li X., Heyer W. D. Homologous recombination in DNA repair
and DNA damage tolerance // Cell Res.–2008.–18, N 1.–P. 99–
113.
24. Rodrigue A., Lafrance M., Gauthier M. C., McDonald D.,
Hendzel M., West S. C., Jasin M., Masson J. Y. Interplay bet-
ween human DNA repair proteins at a unique double-strand
break in vivo // EMBO J.–2006.–25, N 1.–P. 222–231.
UDC 577.218
Received 01.06.11
403
TREATMENT OF LYMPHOID CELLS WITH THE TOPOISOMERASE II POISON ETOPOSIDE
|