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Identification of Stem Cell Units in the Terminal End Bud and Duct of the Mouse Mammary Gland.

Kenney NJ, Smith GH, Lawrence E, Barrett JC, Salomon DS - J. Biomed. Biotechnol. (2001)

Bottom Line: Additionally, TUs are located every 250 +/- 75 &mgr;m in ducts or in the terminal end bud 200-600 &mgr;m in diameter.Molecules expressed in TUs were Zonula Occludens-1 and alpha-catenin proteins which were significantly detected in 75%-91% (P <0.001)of the LRCs cells that make up the TU.These data suggest that transitional units may be a group of label-retaining stem cells and maybe involved in the developmental or cancer process.

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ABSTRACT
The mouse mammary gland may undergo cycles of proliferation, terminal differentiation, tissue remodeling, and more importantly malignant transformation.Mammary epithelial stem cells and their progeny participate in these processes.Mammary epithelial stem cells are multipotent, exhibit properties of self renewal (up to 7 divisions)and may exist either as long-lived nondividing cells or as proliferating-differentiating cells. The focus of this study was to locate stem cells by identifying them as long-lived, label-retaining mammary epithelial cells (LRCs)in growth active (developing)or growth static (aged)mammary ducts. Initially, primary epithelial cells were pulse labeled with either fluorescent tracker dye and/or BrdU. Cells were then transplanted into cleared juvenile syngeneic mammary fat pads and held for 5 weeks or 8 weeks. In this study, we demonstrate that LRCs are stem cells and their progeny (transitional cells)are arranged as transitional units (TUs). Additionally, TUs are located every 250 +/- 75 &mgr;m in ducts or in the terminal end bud 200-600 &mgr;m in diameter. Molecules expressed in TUs were Zonula Occludens-1 and alpha-catenin proteins which were significantly detected in 75%-91% (P <0.001)of the LRCs cells that make up the TU. These data suggest that transitional units may be a group of label-retaining stem cells and maybe involved in the developmental or cancer process.

No MeSH data available.


Related in: MedlinePlus

Colocalization of α-catenin mRNA, protein and BrdU/TLC positivity in 8 week-old C57 Bl6N aged mammary duct. (A–B) Detection of α-catenin mRNA (blue) and BrdU immunostaining (brown) in mammary ducts hybridized to a digoxigenin-UTP labeled α-catenin probe. (B) Area highlighted in (A) (arrow) under high magnification. Note brightly stained BrdU cells are arranged as TUs and appear to be located just proximal to the subtending duct. Inset in (B) represents control section for BrdU staining (secondary antibody alone).Scale bar in (A), 660 μm, and (B), 260 μm.
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Figure 4: Colocalization of α-catenin mRNA, protein and BrdU/TLC positivity in 8 week-old C57 Bl6N aged mammary duct. (A–B) Detection of α-catenin mRNA (blue) and BrdU immunostaining (brown) in mammary ducts hybridized to a digoxigenin-UTP labeled α-catenin probe. (B) Area highlighted in (A) (arrow) under high magnification. Note brightly stained BrdU cells are arranged as TUs and appear to be located just proximal to the subtending duct. Inset in (B) represents control section for BrdU staining (secondary antibody alone).Scale bar in (A), 660 μm, and (B), 260 μm.

Mentions: The next set of experiments determined if cell adhesion moleculeswere associated with label-retaining stem cells by identifying these cells under immunofluorescence, immunohistochemistry, in situ Hybridization (ISH) or fluorescent in situ Hybridization (FISH). The results suggest that, α-catenin mRNA colocalized with 98% (P < 0.001) of brightly stained BrdU-LRCs cells which were positioned along the end bud (Figures 4A and 4B, Table 1). In comparison to nonlabeled mammary ducts, α-catenin mRNA was also detected in 40% (P < 0.01) of labeled ductal cells. In addition, the α-catenin protein was detected in 75% ± 2% (P < 0.001) of the epithelial cells of the TEB which clearly associated with TUs (Figures 4A and 4B) (Table 1, photomicrographs not shown). There were no significant correlations between β-catenin and E-cadherin expression with TUs or LRCs (P < 0.01) (Table 1). However, ZO-1 immunostaining was detected in 91% (P < 0.001) of the bright LRCs (Figures 5A and 5B) but was not as significant as α-catenin (P < 0.01)(photomicrographs not shown and summarized in Table 1).


Identification of Stem Cell Units in the Terminal End Bud and Duct of the Mouse Mammary Gland.

Kenney NJ, Smith GH, Lawrence E, Barrett JC, Salomon DS - J. Biomed. Biotechnol. (2001)

Colocalization of α-catenin mRNA, protein and BrdU/TLC positivity in 8 week-old C57 Bl6N aged mammary duct. (A–B) Detection of α-catenin mRNA (blue) and BrdU immunostaining (brown) in mammary ducts hybridized to a digoxigenin-UTP labeled α-catenin probe. (B) Area highlighted in (A) (arrow) under high magnification. Note brightly stained BrdU cells are arranged as TUs and appear to be located just proximal to the subtending duct. Inset in (B) represents control section for BrdU staining (secondary antibody alone).Scale bar in (A), 660 μm, and (B), 260 μm.
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Related In: Results  -  Collection

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Figure 4: Colocalization of α-catenin mRNA, protein and BrdU/TLC positivity in 8 week-old C57 Bl6N aged mammary duct. (A–B) Detection of α-catenin mRNA (blue) and BrdU immunostaining (brown) in mammary ducts hybridized to a digoxigenin-UTP labeled α-catenin probe. (B) Area highlighted in (A) (arrow) under high magnification. Note brightly stained BrdU cells are arranged as TUs and appear to be located just proximal to the subtending duct. Inset in (B) represents control section for BrdU staining (secondary antibody alone).Scale bar in (A), 660 μm, and (B), 260 μm.
Mentions: The next set of experiments determined if cell adhesion moleculeswere associated with label-retaining stem cells by identifying these cells under immunofluorescence, immunohistochemistry, in situ Hybridization (ISH) or fluorescent in situ Hybridization (FISH). The results suggest that, α-catenin mRNA colocalized with 98% (P < 0.001) of brightly stained BrdU-LRCs cells which were positioned along the end bud (Figures 4A and 4B, Table 1). In comparison to nonlabeled mammary ducts, α-catenin mRNA was also detected in 40% (P < 0.01) of labeled ductal cells. In addition, the α-catenin protein was detected in 75% ± 2% (P < 0.001) of the epithelial cells of the TEB which clearly associated with TUs (Figures 4A and 4B) (Table 1, photomicrographs not shown). There were no significant correlations between β-catenin and E-cadherin expression with TUs or LRCs (P < 0.01) (Table 1). However, ZO-1 immunostaining was detected in 91% (P < 0.001) of the bright LRCs (Figures 5A and 5B) but was not as significant as α-catenin (P < 0.01)(photomicrographs not shown and summarized in Table 1).

Bottom Line: Additionally, TUs are located every 250 +/- 75 &mgr;m in ducts or in the terminal end bud 200-600 &mgr;m in diameter.Molecules expressed in TUs were Zonula Occludens-1 and alpha-catenin proteins which were significantly detected in 75%-91% (P <0.001)of the LRCs cells that make up the TU.These data suggest that transitional units may be a group of label-retaining stem cells and maybe involved in the developmental or cancer process.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
The mouse mammary gland may undergo cycles of proliferation, terminal differentiation, tissue remodeling, and more importantly malignant transformation.Mammary epithelial stem cells and their progeny participate in these processes.Mammary epithelial stem cells are multipotent, exhibit properties of self renewal (up to 7 divisions)and may exist either as long-lived nondividing cells or as proliferating-differentiating cells. The focus of this study was to locate stem cells by identifying them as long-lived, label-retaining mammary epithelial cells (LRCs)in growth active (developing)or growth static (aged)mammary ducts. Initially, primary epithelial cells were pulse labeled with either fluorescent tracker dye and/or BrdU. Cells were then transplanted into cleared juvenile syngeneic mammary fat pads and held for 5 weeks or 8 weeks. In this study, we demonstrate that LRCs are stem cells and their progeny (transitional cells)are arranged as transitional units (TUs). Additionally, TUs are located every 250 +/- 75 &mgr;m in ducts or in the terminal end bud 200-600 &mgr;m in diameter. Molecules expressed in TUs were Zonula Occludens-1 and alpha-catenin proteins which were significantly detected in 75%-91% (P <0.001)of the LRCs cells that make up the TU. These data suggest that transitional units may be a group of label-retaining stem cells and maybe involved in the developmental or cancer process.

No MeSH data available.


Related in: MedlinePlus