Baker Institute for Animal Health, Ithaca , United States.
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
J Mammary Gland Biol Neoplasia. 2022 Dec;27(3-4):253-269. doi: 10.1007/s10911-022-09525-7. Epub 2022 Oct 3.
Mammary stem/progenitor cells are fundamental for mammary gland development and function. However, much remains to be elucidated regarding their function in mammals beyond the traditionally studied rodents, human, and to a lesser extent, ruminants. Due to the growing appreciation for microRNAs (miRNAs) as regulators of stem cells and their progenitors, we compared miRNA expression in mammary stem/progenitor cells from mammals with varying mammary stem/progenitor activity in vitro, in order to identify miRNA candidates that regulate stem/progenitor self-renewal and function. Mammosphere-derived epithelial cells (MDECs), which are primary cell lines enriched in mammary stem and progenitor cells, were generated from six mammalian species (i.e., cow, human, pig, horse, dog, and rat) and small RNA sequencing was performed. We identified 9 miRNAs that were significantly differentially expressed in MDEC cultures with a low versus high mammary stem/progenitor activity. miR-92b-3p was selected for functional follow-up studies, as this miRNA is understudied in primary mammary cells but has well-described gene targets that are known to regulate mammary stem/progenitor activity. Altering the expression of miR-92b-3p in MDECs from species with low stem/progenitor activity (human and cow) and those with high stem/progenitor activity (dog and rat) via inhibition and overexpression, respectively, resulted in significantly decreased mammosphere formation of human MDECs, but showed no significant effects in cow, dog, or rat MDECs. This study is the first to perform small RNA sequencing in MDECs from various mammals and highlights that conserved miRNAs can have different functions in mammary stem/progenitor cells across species.
乳腺干/祖细胞对于乳腺的发育和功能至关重要。然而，除了传统研究的啮齿动物、人类以及在较小程度上的反刍动物之外，它们在哺乳动物中的功能仍有许多需要阐明的地方。由于越来越认识到 microRNAs（miRNAs）作为干细胞及其祖细胞的调节剂的作用，我们比较了在体外具有不同乳腺干/祖细胞活性的哺乳动物的乳腺干/祖细胞中的 miRNA 表达，以鉴定调节干细胞/祖细胞自我更新和功能的 miRNA 候选物。从六种哺乳动物（即牛、人、猪、马、狗和鼠）中生成了乳腺球衍生的上皮细胞（MDEC），这些细胞是富含乳腺干和祖细胞的原代细胞系，并进行了小 RNA 测序。我们鉴定了 9 个在乳腺干/祖细胞活性低与高的 MDEC 培养物中差异表达显著的 miRNA。选择 miR-92b-3p 进行功能后续研究，因为该 miRNA 在原代乳腺细胞中研究较少，但具有描述良好的靶基因，这些靶基因已知可以调节乳腺干/祖细胞的活性。通过抑制和过表达分别改变低干/祖细胞活性（人、牛）和高干/祖细胞活性（狗、鼠）物种的 MDEC 中的 miR-92b-3p 的表达，导致人 MDEC 的乳腺球形成显著减少，但在牛、狗或鼠 MDEC 中没有显示出显著影响。这项研究是首次在各种哺乳动物的 MDEC 中进行小 RNA 测序，并强调了保守的 miRNA 在不同物种的乳腺干/祖细胞中可能具有不同的功能。
