Do we need Y chromosome for successful reproduction?

哺乳动物的繁殖通常需要雌性提供的卵母细胞和雄性提供的精子来实现受精。我们超越了这一惯例，并提出了这样的假设，即任何性别的成年个体都可以被诱导产生异性配子，并且这些配子在辅助受精中起作用。这一假设的前提来自我们最近发表的研究，这些研究表明，具有有限或没有Y染色体基因的基因工程雄性小鼠可以通过辅助受精（ART）成功繁殖，以及细胞重编程和分化领域的重大进展。我们的实验室已经表明，在小鼠中，只有两个Y染色体基因，睾丸决定因子Sry和精子发生驱动因子Eif2s3y，足以使雄性产生在ART中有功能的单倍体雄性配子。我们随后证明，这两个基因的功能可以被其他染色体上编码的同源基因所取代，一只X染色体（XO）缺乏所有Y染色体基因的小鼠可以产生雄性配子，并在辅助受精后产生健康的后代。我们的合作者Mitinori Saitou的实验室已经表明，男性和女性配子都可以从诱导多能干细胞（iPSC）分化为原始生殖细胞样细胞（PGCLC）中获得。在这个建议中，我们结合我们的研究结果和专业知识，并提出3个问题：目标1。成年雌性小鼠能产生辅助受精的雄性配子吗？目标2.成年雄性小鼠能否产生辅助受精的雌性配子？目标3。 一只成年的老鼠是否可以产生单亲后代？为了解决这些问题，我们将从给定性别的成年小鼠中开发体细胞系，重新编程为iPSC，鉴定丢失一条性染色体并成为XO的克隆，并分化为PGCLC。为了产生雄性配子，我们将转基因添加精子发生驱动程序，并将PGCLC移植到新生雄性的睾丸中。为了产生雌性配子，我们将在体外重建卵巢并将其移植到受体雌性的卵巢囊下。我们将使用辅助生殖来测试这种衍生的雄性和雌性配子的功能。为了产生单亲后代，来自同一个体的雄性和雌性配子将用于受精。该项目的发现将影响我们对性别特异性差异的理解，特别是关于性染色体和X和Y基因对生殖系发育的影响。如果成功，我们还将为该领域提供一个原则证明，即两性后代可以从一个个体获得，这将对物种保护产生影响。

Mammalian reproduction conventionally requires oocytes provided by a female and sperm provided by a male to achieve fertilization. We go beyond this convention and propose the hypothesis that an adult individual of any sex can be induced to produce gametes of the opposite sex, and that these gametes are functional in assisted fertilization. The premise for this hypothesis comes from our recently published studies demonstrating that genetically engineered male mice with limited or no Y chromosome genes can successfully reproduce by assisted fertilization (ART), and from significant advancements in field of cell reprogramming and differentiation. Our laboratory has shown that in the mouse only two Y chromosome genes, testis determinant Sry and spermatogenesis driver Eif2s3y, are sufficient for a male to produce haploid male gametes functional in ART. We have subsequently demonstrated that the function of these two genes could be replaced by that of their homologues encoded on other chromosomes, and that a mouse with a single X chromosome (XO) lacking all Y chromosome genes can produce male gametes and sire healthy offspring after assisted fertilization. The laboratory of our collaborator, Mitinori Saitou, has shown that both male and female gametes can be obtained from induced pluripotent stem cells (iPSC) differentiated into primordial germ cell like-cells (PGCLC). In this proposal, we marry our findings and expertise and ask 3 questions: Aim 1. Can an adult female mouse produce male gametes functional in assisted fertilization? Aim 2. Can an adult male mouse produce female gametes functional in assisted fertilization? Aim 3. Can an adult mouse of either sex sire uniparental offspring? To address these questions we will develop somatic cell lines from an adult mouse of a given sex, reprogram to iPSC, identify the clones that have lost one sex chromosome and became XO, and differentiate into PGCLC. To produce male gametes we will transgenically add a spermatogenesis driver and transplant PGCLC to testes from neonatal males. To produce female gametes we will reconstitute ovaries in vitro and transplant them under ovarian bursa of recipient females. We will test the function of such derived male and female gametes using assisted reproduction. To produce uniparental offspring, male and female gametes derived from the same individual will be used for fertilization. The findings from this project will impact on our understanding of sex specific differences, especially pertaining to effects of sex chromosomes and X and Y genes on germline development. If successful, we will also provide the field with a proof-of-principle that offspring of both sexes can be obtained from a single individual, which will impact on species preservation.