Selective segregation of DNA strands persists in long label retaining mammary cells during pregnancy
Selective segregation of DNA strands persists in long label retaining mammary cells during pregnancy
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DOI：
10.1186/bcr2188
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发表时间：
2008-01-01
影响因子：
7.4
通讯作者：
Smith, Gilbert H.
中科院分区：
文献类型：
--
作者：
Booth, Brian W.;Boulanger, Corinne A.;Smith, Gilbert H.
在妊娠期间，乳腺上皮细胞在干细胞/祖细胞的促进下经历了极端的增殖和分化。非妊娠小鼠的乳腺上皮含有长标记保留上皮细胞（LREC），其不对称分裂并保留其模板DNA链。在alveogenesis的LREC的作用尚未determined.Methods我们进行了免疫组织化学和放射自显影小鼠乳腺已标记5-溴脱氧尿苷（5 BrdU）在异速生长的导管，调查在怀孕期间的DNA标记保留和雌激素受体α或孕激素受体的共表达。在妊娠期间给予第二种DNA标记（[H-3]-胸苷），以鉴定标记保留细胞（LRC），随后进入细胞周期。使用这种方法使我们能够研究5 BrdU与平滑肌肌动蛋白，CD 31，细胞角蛋白和结蛋白在长追踪期后的妊娠小鼠乳腺组织中导管周围或腺泡周围LRC中的共定位，以鉴定LRC。占上皮细胞亚群的1.0%妊娠改变了表达雌激素受体α的LREC的百分比。位于整个腺体的导管周围或腺泡周围的LRC不表达上皮、内皮或肌上皮标记物，并且这些未定义的LRC在整个妊娠期间持续存在。此外，新的循环LREC（[H-3]-胸苷保留）出现在alveologenesis，和LRC发现在其他组织类型（例如，内皮和神经）内的乳腺脂肪垫成为双标记在怀孕期间，这表明他们也可能划分不对称。结论我们的研究结果支持的前提下，有一个亚群的LREC在小鼠乳腺中，持续在alveologenesis。这些细胞在怀孕期间对激素信号作出反应，并进入细胞周期，同时继续选择性地保留其原始模板DNA。此外，在导管周围或腺泡周围位置发现非上皮LRC。这些LRC也在怀孕期间进入细胞周期。在肺泡发生过程中，新产生的标记保留（[H-3]-胸苷）上皮细胞出现在扩张的肺泡内，并继续循环和保留其原始模板DNA（[H-3]-胸苷）链，如通过5 BrdU的第二次脉冲所确定的。
Introduction During pregnancy the mammary epithelial compartment undergoes extreme proliferation and differentiation, facilitated by stem/progenitor cells. Mouse mammary epithelium in nonpregnant mice contains long label-retaining epithelial cells (LREC) that divide asymmetrically and retain their template DNA strands. The role of LREC during alveogenesis has not been determined.Methods We performed immunohistochemistry and autoradiography on murine mammary glands that had been labeled with 5-bromodeoxyuridine (5BrdU) during allometric ductal growth to investigate the co-expression of DNA label retention and estrogen receptor-alpha or progesterone receptor during pregnancy. A second DNA label ([H-3]-thymidine) was administered during pregnancy to identify label-retaining cells (LRC), which subsequently enter the cell cycle. Use of this methodology allowed us to investigate the co-localization of 5BrdU with smooth muscle actin, CD31, cytokeratin, and desmin in periductal or peri-acinar LRC in mammary tissue from pregnant mice subsequent to a long chase period in order to identify LRC.Results Estrogen receptor-alpha positive and progesterone receptor positive cells represented approximately 30% to 40% of the LREC, which is under 1.0% of the epithelial subpopulation. Pregnancy altered the percentage of LREC expressing estrogen receptor-alpha. LRC situated in periductal or peri-acinar positions throughout the gland do not express epithelial, endothelial, or myoepithelial markers, and these undefined LRCs persist throughout pregnancy. Additionally, new cycling LREC ([H-3]-thymidine retaining) appear during alveologenesis, and LRC found in other tissue types (for example, endothelium and nerve) within the mammary fat pad become double labeled during pregnancy, which indicates that they may also divide asymmetrically.Conclusions Our findings support the premise that there is a subpopulation of LREC in the mouse mammary gland that persists during alveologenesis. These cells react to hormonal cues during pregnancy and enter the cell cycle while continuing to retain, selectively, their original template DNA. In addition, nonepithelial LRC are found in periductal or peri-acinar positions. These LRC also enter the cell cycle during pregnancy. During alveologenesis, newly created label-retaining ([H-3]thymidine) epithelial cells appear within the expanding alveoli and continue to cycle and retain their original template DNA ([H-3]-thymidine) strands, as determined by a second pulse of 5BrdU.