"Sperm maturation and capacitation: Roles of Chaperone Proteins, Clusterin and Hsp70"

提高施肥效率将导致农业畜牧业生产的成功。精子在睾丸中产生，但睾丸精子不能使卵子受精。它们在通过附睾（称为精子成熟）和在雌性生殖道内迁移（称为获能）的过程中必须经历生化修饰。由附睾上皮细胞分泌的卵细胞外基质--透明质酸（ZP）结合蛋白存款在转运精子表面。这些蛋白质中的一些倾向于聚集并且在小的附睾体积内，它们可能沉淀而没有拯救机制。也由附睾上皮细胞分泌的异丙肾上腺素（CLU）具有伴侣性质，并倾向于在其疏水（非极性，斥水）结构域与其他蛋白质结合。我们建议，CLU防止ZP结合蛋白沉淀和伴侣他们的精子表面。将进行生物化学实验以验证CLU可以防止ZP结合蛋白的沉淀/聚集（例如，芳基硫酸酯酶A，SED 1），和CLU的伴侣蛋白活性将通过比较在Clu遗传无效小鼠与野生型小鼠中精子上ZP结合蛋白的存在来评估。在获能过程中，我们最近的研究结果表明，ZP结合蛋白聚集成复合物，另一个伴侣蛋白Hsp 70可能在这种聚集中发挥作用。我们将通过质谱鉴定复合物中的ZP结合蛋白，并通过评估用Hsp 70处理非获能精子后精子是否具有更多的可交配性（获能）来验证Hsp 70的作用。我们提出的工作的结果可以被翻译为增强具有低水平的某些ZP结合蛋白的精子的可交配性。它们将用CLU +所需的ZP结合蛋白以及Hsp 70处理以增强复合物的形成。我们的研究也将更好地了解精子的成熟和获能过程。

Raising efficiency in fertilization would lead to increased success in agricultural animal production. Sperm are produced in the testis, but testicular sperm cannot fertilize an egg. They have to undergo biochemical modifications during their transit through the epididymis (called sperm maturation) and their migration inside the female reproductive tract (called capacitation). A number of egg extracellular matrix, zona pellucida (ZP), binding proteins secreted by epididymal epithelial cells deposit onto the transit sperm surface. Some of these proteins tend to aggregate and within a small epididymal volume, they may precipitate without rescuing mechanisms. Clusterin (CLU), also secreted by epididymal epithelial cells, has a chaperone property and propensity to bind to other proteins at their hydrophobic (non-polar, water repellant) domains. We propose that CLU prevents ZP binding proteins from precipitation and chaperones them to the sperm surface. Biochemical experiments will be performed to validate that CLU can prevent precipitation/aggregation of ZP binding proteins (e.g., arylsulfatase A, SED1), and CLU's chaperone activity will be assessed by comparing the presence of ZP binding proteins on sperm in Clu genetically null mice versus that in wild type mice. During capacitation, our recent results suggest that ZP binding proteins conglomerate as complexes, and another chaperone Hsp70 protein may play roles in this conglomeration. We will identify ZP binding proteins in the complex by mass spectrometry and validate the role of Hsp70 by assessing whether sperm have more fertilizing ability (capacitated) after treating non-capacitated sperm with Hsp70. Results from our proposed work can be translated to enhance fertilizing ability of sperm that have low levels of certain ZP binding proteins. They will be treated with CLU + the desired ZP binding proteins, as well as Hsp70 to enhance the complex formation. Our study will also give a better understanding of sperm maturation and capacitation processes.