Regulation and functions of male-derived shed microvesicles in Drosophila reproduction

尽管雄性和雌性在交配时有一个共同的目标，那就是产生携带自己基因副本的后代，但同时它们之间也存在着一个重要的冲突。一方面，许多物种的雄性可以通过与许多雌性交配并防止其他雄性竞争来最好地维持自己的基因库，而雌性往往最好是从多个雄性身上采集精子。三年前，我们开始研究男性如何适应这场性别之战。我们推测，雄性已经发展出了向雌性传递信号的特殊方式，使它们的精子处于最佳状态，并阻止其他雄性与这些雌性交配。我们决定对果蝇进行研究，部分原因是我们已经知道，雄性果蝇已经发展出了巧妙的方法来对抗繁殖之战。它们在雌性子宫中组装一个塞子，阻止雌性生殖，并改变雌性行为，这样雌性就会拒绝其他雄性雌性随后的进取。苍蝇是这类研究的理想选择，因为它们可以很容易地被操纵来识别相关基因，并找出它们是如何工作的。在所有已知的与人类疾病有关的基因中，大约70%也在苍蝇身上发现。人类生物学中的许多基本机制最初是在苍蝇或其他简单生物身上研究的，然后才在人类身上进行研究。我们正在研究苍蝇体内的一种雄性腺体，称为附腺，它似乎与人类的前列腺和精囊有许多相似之处，精囊是精液的主要成分。我们已经证明，这个腺体中的一种细胞会分泌微小的膜结合包，这些包在交配时传递给雌性并与精子融合。这些被称为外体的组件需要在交配后改变雌性的行为。值得注意的是，人类的前列腺也会产生能与精子融合的外切体。我们的工作开始揭示这些外切体是如何形成的，以及它们是如何影响精子的，我们也开始了解外切体生产缺陷可能与前列腺癌的某些方面有关，我们现在正在与临床同事跟进这些想法。最近，我们发现附腺中的另一种细胞分泌更大的膜绑定结构，称为脱落微囊(SMV)，这些结构也在交配时大量传递给雌性。这些小泡携带着几种已知的关键蛋白质，这些蛋白质可以在交配后推动雌性发生变化，比如增加产卵、精子存储、交配塞子形成和改变交配行为。SMV结合在一起，在女性生殖道的一部分形成交配塞子，而在其他部分，它们保持完好，但释放出其中一种附着的蛋白质，然后结合到精子上，并允许其储存。这些SMV也可能与雌性细胞结合，增加了它们通过这种方式与雌性沟通的可能性。参与这一过程的几个重要苍蝇分子与哺乳动物的生殖蛋白有关。事实上，在苍蝇精液中发现SMV解释了苍蝇和哺乳动物生殖中的一个谜团--分泌到精液中的几种蛋白质看起来应该附着在膜上，而不是分泌。我们将研究SMV是如何产生的，研究它们在交配后在雌性体内的作用，以及这些事件是如何由副腺中制造的蛋白质控制的。这项工作不仅将帮助我们理解生殖的基本原理，还可能为我们的生殖治疗和避孕提供新的想法。SMV在血液凝结、炎症和生长方面也很重要。我们有证据表明，对这些不同过程的基本控制是相似的，这为我们的工作提供了对这些过程出错的疾病的新见解。因此，我们提出的工作，着眼于一个重要但以前难以解决的问题，可能会对与人类健康相关的生物学领域产生影响。

Although males and females share a common goal when they mate, the production of offspring who carry copies of their genes, there is at the same time an important conflict between them. While on the one hand, males of many species can best maintain their gene pool by mating with many females and preventing other males from competing, females are often best served by sampling sperm from multiple males. Three years ago, we started to study the ways in which males have adapted to fight this battle of the sexes. We speculated that males had developed specialised ways of delivering signals to females that made their sperm work at their best and also stopped other males from mating with these females. We decided to work with the fruit fly, partly because it was already known that male flies had developed ingenious ways to fight the reproductive battle. They assemble a plug in the female uterus that blocks remating and also alter female behaviour so she rejects subsequent advances from other males. Flies are ideal for studies of this kind because they can be easily manipulated to identify the genes involved and find out how they work. About 70% of all genes known to be involved in human disease are also found in flies. Lots of the basic mechanisms in human biology were originally studied in flies or other simple organisms before being looked at in humans. We are studying a male gland in flies called the accessory gland that seems to share many features of the human prostate and seminal vesicles, which generate most of the main components of semen. We have already shown that one type of cell in this gland secretes tiny membrane-bound packages that are passed into females on mating and fuse to sperm. These packages, called exosomes, are required to alter female behaviour after mating. Remarkably the human prostate also produces exosomes that fuse to sperm. Our work is starting to reveal how these exosomes are made and how they affect sperm, and we are beginning to see how defects in exosome production might be involved in aspects of prostate cancer, ideas that we are now following up with clinical colleagues.Recently we discovered that another type of cell in the accessory gland secretes larger membrane-bound structures called shed microvesicles (SMVs) that are also passed to females in huge numbers during mating. These vesicles carry several key proteins that are already known to drive changes in the female after mating, like increased egg laying, sperm storage, mating plug formation and altered remating behaviour. SMVs coalesce to make a mating plug in one part of the female reproductive tract, while in other parts, they remain intact, but release one of their attached proteins, which then binds to sperm and allows it to be stored. These SMVs may also bind to female cells, raising the possibility that they could communicate to females in this way.Several important fly molecules involved in this process are related to mammalian reproductive proteins. In fact, the discovery of SMVs in fly semen explains a mystery in both fly and mammalian reproduction - several proteins secreted into semen look like they should be attached to membranes, and not secreted. We will study how SMVs are made, work out what they do in females after mating and how these events are controlled by proteins made in the accessory gland. This work will not only help us to understand fundamental principles of reproduction, it may give us new ideas for reproductive therapies and contraception. SMVs are also important in blood clotting, inflammation and growth. We have evidence that the basic controls on these different processes are similar, opening up the possibility that our work will provide new insights into diseases where these processes go wrong. Our proposed work, looking into an important, but previously intractable problem, may therefore impact on several areas of biology relevant to human health.