Background Studying the composition and developmental mechanisms in mammary gland is crucial for healthy growth of newborns. The mammary gland is inherently heterogeneous, and its physiological function dependents on ...Background Studying the composition and developmental mechanisms in mammary gland is crucial for healthy growth of newborns. The mammary gland is inherently heterogeneous, and its physiological function dependents on the gene expression of multiple cell types. Most studies focused on epithelial cells, disregarding the role of neighboring adipocytes.Results Here, we constructed the largest transcriptomic dataset of porcine mammary gland cells thus far. The dataset captured 126,829 high-quality nuclei from physiological mammary glands across five developmental stages(d 90 of gestation, G90;d 0 after lactation, L0;d 20 after lactation, L20;2 d post natural involution, PI2;7 d post natural involution, PI7). Seven cell types were identified, including epithelial cells, adipocytes, endothelial cells, fibroblasts cells, immune cells, myoepithelial cells and precursor cells. Our data indicate that mammary glands at different developmental stages have distinct phenotypic and transcriptional signatures. During late gestation(G90), the differentiation and proliferation of adipocytes were inhibited. Meanwhile, partly epithelial cells were completely differentiated. Pseudo-time analysis showed that epithelial cells undergo three stages to achieve lactation, including cellular differentiation, hormone sensing, and metabolic activation. During lactation(L0 and L20), adipocytes area accounts for less than 0.5% of mammary glands. To maintain their own survival, the adipocyte exhibited a poorly differentiated state and a proliferative capacity. Epithelial cells initiate lactation upon hormonal stimulation. After fulfilling lactation mission, their undergo physiological death under high intensity lactation. Interestingly, the physiological dead cells seem to be actively cleared by immune cells via CCL21-ACKR4 pathway. This biological process may be an important mechanism for maintaining homeostasis of the mammary gland. During natural involution(PI2 and PI7), epithelial cell populations dedifferentiate into mesenchymal stem cells to maintain the lactation potential of mammary glands for the next lactation cycle.Conclusion The molecular mechanisms of dedifferentiation, proliferation and redifferentiation of adipocytes and epithelial cells were revealed from late pregnancy to natural involution. This cell transcriptomic profile constitutes an essential reference for future studies in the development and remodeling of the mammary gland at different stages.展开更多
Genomic structural variations(SVs),particularly insertions,deletions and inversions,can contribute to the heterogeneity of millions of nucleotides within a genome,and are likely to make an important contribution to bi...Genomic structural variations(SVs),particularly insertions,deletions and inversions,can contribute to the heterogeneity of millions of nucleotides within a genome,and are likely to make an important contribution to biological diversity and phenotypic variation(Alkan et al.,2011;Bickhart and Liu,2014).With the rapid development of the next-generation sequencing technologies and the new assembly methodologies,the展开更多
基金supported by the National Key R&D Program of China (2020YFA0509500,2021YFD1301101 and 2021YFA0805903)the Sichuan Science and Technology Program+3 种基金(2023YFN0088 and 2021YFYZ0030)the National Center of Technology Innovation for Pigs (SCCXTD-2023-08)the National Natural Science Foundation of China (32272837 and 32225046)Tianfu Agricultural Master Project。
文摘Background Studying the composition and developmental mechanisms in mammary gland is crucial for healthy growth of newborns. The mammary gland is inherently heterogeneous, and its physiological function dependents on the gene expression of multiple cell types. Most studies focused on epithelial cells, disregarding the role of neighboring adipocytes.Results Here, we constructed the largest transcriptomic dataset of porcine mammary gland cells thus far. The dataset captured 126,829 high-quality nuclei from physiological mammary glands across five developmental stages(d 90 of gestation, G90;d 0 after lactation, L0;d 20 after lactation, L20;2 d post natural involution, PI2;7 d post natural involution, PI7). Seven cell types were identified, including epithelial cells, adipocytes, endothelial cells, fibroblasts cells, immune cells, myoepithelial cells and precursor cells. Our data indicate that mammary glands at different developmental stages have distinct phenotypic and transcriptional signatures. During late gestation(G90), the differentiation and proliferation of adipocytes were inhibited. Meanwhile, partly epithelial cells were completely differentiated. Pseudo-time analysis showed that epithelial cells undergo three stages to achieve lactation, including cellular differentiation, hormone sensing, and metabolic activation. During lactation(L0 and L20), adipocytes area accounts for less than 0.5% of mammary glands. To maintain their own survival, the adipocyte exhibited a poorly differentiated state and a proliferative capacity. Epithelial cells initiate lactation upon hormonal stimulation. After fulfilling lactation mission, their undergo physiological death under high intensity lactation. Interestingly, the physiological dead cells seem to be actively cleared by immune cells via CCL21-ACKR4 pathway. This biological process may be an important mechanism for maintaining homeostasis of the mammary gland. During natural involution(PI2 and PI7), epithelial cell populations dedifferentiate into mesenchymal stem cells to maintain the lactation potential of mammary glands for the next lactation cycle.Conclusion The molecular mechanisms of dedifferentiation, proliferation and redifferentiation of adipocytes and epithelial cells were revealed from late pregnancy to natural involution. This cell transcriptomic profile constitutes an essential reference for future studies in the development and remodeling of the mammary gland at different stages.
基金supported by the National High Technology Research and Development Program of China(863 Program)(No.2013AA102502)the National Natural Science Foundation of China(Nos.31372284 and 31402046)+1 种基金the Fund of Fok Ying-Tung Education Foundation(No.141117)the Fund for Distinguished Young Scientists of Sichuan Province(No. 2013JQ0013)
文摘Genomic structural variations(SVs),particularly insertions,deletions and inversions,can contribute to the heterogeneity of millions of nucleotides within a genome,and are likely to make an important contribution to biological diversity and phenotypic variation(Alkan et al.,2011;Bickhart and Liu,2014).With the rapid development of the next-generation sequencing technologies and the new assembly methodologies,the
