Mammalian milk paradigm secretion, transport functional uptake mobile silen RNA

在植物和无脊椎动物中，长RNA和沉默的小RNA(S)在细胞之间和远距离移动，在遥远的组织中发挥调节功能。最近，哺乳动物体液和细胞外间隙中分泌的微泡被发现含有RNA；而且，这些微泡可能内化在受体细胞中。在血清中也检测到名为Argavites(Agos)的sRNA效应蛋白。这些发现引发了人们的猜测，即哺乳动物细胞外RNA与脂质和/或效应蛋白结合后，可能在被靶细胞/组织摄取后具有生物学功能。然而，目前几乎没有实验证据支持这一观点。我们的实验室率先研究了 他是最早在哺乳动物细胞中建立RNA沉默、内膜和囊泡运输之间联系的人之一。最近，我们发现人和牛乳中含有生理数量的调节性微小(Mi)RNA，特别是集中在乳脂球(MFG)中，乳脂球是新生儿的脂肪来源。此外，我们还在MFG和其他牛奶组分中检测到大量特定的agos，这表明与agg结合的miRNA，也许还有其他RNA，可能在喂养过程中功能性地转移到新生的肠道上皮中，也许是远处的器官。利用McManus和Hunter实验室提供的强大的小鼠和基于细胞的遗传工具，我们建议在这里使用哺乳动物奶-一种容易获得和丰富的体液-作为一个范式来研究(I)支持乳腺miRNA分泌的机制，(Ii)含奶miRNAs的蛋白质和脂环境，包括可能与牛奶相关的新的前伴侣，(Iii)支持肠道上皮摄取牛奶miRNA的机制，以及(Iv)在喂养过程中从母亲传给幼崽的乳源性miRNAs是否有效地显示了小鼠的生物活性。根据这一知识，并根据植物和寄生无脊椎动物之间跨王国RNAi转移的明确先例，我们最终将利用我们独特的植物-哺乳动物双重专业知识，解决来自作物的饮食RNA是否可以被植物喂养的小鼠的肠道上皮功能所吸收。

In plants and invertebrates, long RNAs and silencing small (s)RNAs move between cells and over long distances to exert regulatory functions in remote tissues. Recently, micro-vesicles secreted in mammalian body fluids and in the extra-cellular space were found to contain RNA; these, moreover, might be internalized in recipient cells. sRNA effector proteins called Argonautes (AGOs) were also detected in serum. These findings have spurred speculations that mammalian extracellular RNAs bound to lipids and/or effector proteins might have biological functions following their uptake by target cells/tissues. Little, if any, experimental evidence presently supports this idea, however. Our laboratory has pioneered research on non-cell autonomous RNAi and was among the first to establish a link between RNA silencing, endo-membranes and vesicle trafficking in mammalian cells. Recently, we discovered that human and bovine milk contains physiological amounts of regulatory micro (mi)RNAs concentrated, notably, in milk fat globules (MFG), the source of fat for newborns. Moreover, we also detected high amounts of specific AGOs in MFG and other milk fractions, suggesting that AGO-bound miRNA, and perhaps other RNAs, might be functionally transferred into the new born gut epithelium and, perhaps distant organs, during feeding. Taking advantage of the formidable collection of mouse and cell-based genetic tools available from the McManus and Hunter laboratories, we propose here to use mammalian milk -an easily accessible and abundant body fluid- as a paradigm to investigate (i) the mechanisms underpinning miRNA secretion from the mammary gland, (ii) the protein and lipid environment of milk-contained miRNAs, including possibly novel milk-associated AGO partners, (iii) the mechanisms underpinning milk miRNA uptake by the gut epithelium, and (iv) if milk-borne miRNAs transferred from mother to pup during feeding effectively display biological activity in mouse newborns. Drawing from this knowledge and on clear precedents of trans-kingdom RNAi transfer between plants and parasitic invertebrates, we will finally address, using our unique plant-mammal dual expertise, if dietary RNA derived from crops can be functionally taken up by the gut epithelium of plant-fed mice.