Lineage tracing for mammary stem cells using Hopx reporter mice
- VernacularTitle:Hopx报告基因小鼠谱系示踪乳腺干细胞
- Author:
Jianyun SHI
1
;
Wenjing LI
;
Ying PENG
;
Zhenhua JIA
;
Shujin ZHANG
;
Lulu TAN
;
Yitong YUAN
;
Ruochen DU
Author Information
- Publication Type:Journal Article
- Keywords: Hopx; mammary stem cell; lineage tracing; gestational period; acinar formation
- From: Chinese Journal of Tissue Engineering Research 2025;29(13):2720-2727
- CountryChina
- Language:Chinese
- Abstract: BACKGROUND:Mammary stem cells are vital for the development and homeostasis of mammary gland tissue.The occurrence of breast cancer has a close relationship with the mammary stem cells.Recent studies have shown that Hopx,as an important transcriptional regulator of morphogenesis and cell differentiation,has been confirmed to be expressed in a variety of adult stem cells such as nerves,intestines,hair follicles and lungs.However,its role in mammary stem cells has not been reported so far.OBJECTIVE:To investigate whether Hopx expression marks mammary stem cells.METHODS:(1) Female Hopx-LacZ transgenic mice aged 8 weeks were selected to detect the background expression of Hopx in breast tissue by β-galactosidase staining.(2) Female wild-type mice at 4,6,and 8 weeks of age and 14.5 days of gestation were selected for whole-tissue magenta staining and K14 and K8 immunofluorescence staining,respectively.(3) Female Hopx-CreERT2;Rosa26LacZ transgenic mice aged 8 weeks and 17.5 days of gestation were selected and stained with breast β-galactosidase.(4) The 4-week-old female Hopx-CreERT2;Rosa26LacZ transgenic mice were selected.The Cre/loxp system was activated by intraperitoneal injection of tamoxifen (once every other day,three times),and breast β-galactosidase staining was performed 4 weeks after injection.The 8-week-old female Hopx-CreERT2;Rosa26LacZ transgenic mice were selected.The Cre/loxp system was activated by intraperitoneal injection of tamoxifen (once every other day,three times),and breast β-galactosidase staining was performed 4 and 10 weeks after the last injection.(5) Female Hopx-CreERT2;Rosa26LacZ transgenic mice aged 8 weeks were selected.The Cre/loxp system was activated by intraperitoneal injection of tamoxifen (once every other day,three times).Hopx-CreERT2;Rosa26LacZ transgenic mice were pregnant 2 weeks after injection.The mammary tissue of mice at 17.5 days of the first pregnancy and 17.5 days of the third pregnancy was stained with β-galactosidase.RESULTS AND CONCLUSION:(1) The results of β-galactosidase staining showed that the mammary ducts of Hopx-LacZ transgenic mice at 8 weeks of age did contain Hopx-positive cells and were located in the basal epithelia,with a small number.(2) Whole-mount staining of mammary glands and immunofluorescence staining results exhibited that the mammary glands of mice had different characteristics with corresponding developmental stages such as puberty,maturity,and pregnancy,and underwent a series of complex epithelial remodeling processes.(3) The results of β-galactosylase staining showed that Hopx-labeled positive cells in the mammary duct of Hopx-CreERT2;Rosa26LacZ transgenic mice at 17.5 days of gestation increased compared with female Hopx-CreERT2;Rosa26LacZ transgenic mice at 8 weeks of age.(4) The results of β-galactosylase staining showed that the Hopx-labeled positive cells in the mammary glands of 4-and 8-week-old female Hopx-CreERT2;Rosa26LacZ transgenic mice after tamoxifen injection were located in the basal epithelium with a small number.(5) The results of β-galactosidase staining showed that Hopx-labeled positive cells in the mammary glands of mice at 17.5 days of the first and third gestation were located in the basal epithelia around the alveoli,and the number of Hopx-labeled positive cells at 17.5 days of the third gestation was more.(6) In conclusion,Hopx reporter-marked basal epithelial cells belong to dormant mammary stem cells,which are responsible for the growth of the mammary glands during pregnancy and contribute to acinar formation.
