乳腺干细胞的谱系示踪与功能研究

As the second sexual organ of female, the mammary gland plays an important role in the breeding of the offspring. It is of great significance to explore and reveal the development process of the mammary gland. Defining the fate lineage of mouse mammary epithelial cells after birth has become a research hotspot in this field. Previous studies have found that mouse mammary epithelial cells have multi-directional differentiation potential after birth and can contribute to the formation of luminal epithelial cells. However, some studies have found that two types of epithelial cells in the breast maintain their respective differentiation fate after birth, and the myogenic epithelial cells do not have the potential for multi-directional differentiation. The main reason for the controversy is the incompatibility and inaccuracy of genetic lineage tracing. Therefore, we have established a more precise dual homologous recombination genetic targeting tracing technique to simultaneously perform lineage tracing on both types of breast ductal epithelial cells, to reveal the fate map of the two types of epithelial cells under physiological conditions and simulated pathological conditions, and to explore the differentiation potential of postnatal breast stem cells. At the same time, specific gene knockout reveals its molecular regulation mechanism. In summary, the proposed research will help us to define the development of the mammary gland and provide new ideas for the treatment of breast dysplasia, breast hyperplasia and breast cancer.

乳腺作为雌性的第二性征器官，在哺育后代中起着重要作用，探索并揭示乳腺的发育过程意义重大。明确出生后小鼠乳腺上皮细胞的命运谱系已成为该领域的研究热点。前期相关研究发现出生后小鼠乳腺肌生性上皮细胞具有多向分化潜能，可以贡献形成管腔上皮细胞。然而也有研究表明出生后乳腺两类上皮细胞保持各自的分化命运，肌生性上皮细胞并不具有多向分化的潜能。产生争论的主要原因是遗传谱系示踪的不特异性和不准确性。因此，我们建立了更加精准的双同源重组遗传靶向示踪技术，来对乳腺导管两类上皮细胞同时进行谱系示踪，揭示乳腺在生理条件下和模拟病理条件下，两类上皮细胞的命运图谱，探索出生后乳腺干细胞的分化潜能，同时进行特异性基因敲除揭示其分子调控机制。综上，拟开展的研究将帮助我们明确乳腺的发育过程，为乳腺发育不良，乳腺增生和乳腺癌等疾病的治疗等提供新思路。

乳腺作为重要的性征器官，在雌性性征维持和后代哺育中具有重要的作用。成熟的小鼠乳腺组织包括乳腺导管和包绕着导管的间质细胞，乳腺导管主要由位于管腔内侧的管腔上皮细胞和位于导管外侧的肌生性上皮细胞构成，管腔上皮细胞可以分泌激素及其受体，维持机体正常的性征。随着动情周期的变化，受激素调节，成体乳腺的结构呈现周期性变化。在哺乳时，管腔上皮细胞可以形成多个乳腺小叶结构来分泌乳汁，而位于管腔外侧的肌生性上皮细胞可以通过收缩，将乳汁运输到乳头的位置，来哺育后代。间质细胞包括脂肪细胞，成纤维细胞，内皮细胞和巨噬细胞等，主要为乳腺导管提供营养和支持。我们对不同生理条件下的肌生性上皮细胞进行谱系示踪发现我们遗传标记的肌生性上皮细胞不会贡献形成管腔上皮细胞。而当我们在Kit阳性的乳腺上皮细胞中过表达抑制细胞增殖的基因P21来抑制Kit阳性的细胞的增殖，可以激发肌生性上皮细胞的多向分化潜能，贡献形成管腔上皮细胞，这些肌生性上皮细胞来源的上皮细胞在怀孕及哺乳时产生乳腺小叶上皮细胞。