Physiological function of seminal vesicle secretions on male fecundity

Noda, T, Ikawa, M. Physiological function of seminal vesicle secretions on male fecundity. Reprod Med Biol. 2019; 18: 241– 246. https://doi.org/10.1002/rmb2.1228

Identification of ejaculated proteins in the house mouse (Mus domesticus) via isotopic labeling

<p>Abstract</p> <p>Background</p> <p>Seminal fluid plays an important role in successful fertilization, but knowledge of the full suite of proteins transferred from males to females during copulation is incomplete. The list of ejaculated proteins remains particularly scant in one of the best-studied mammalian systems, the house mouse (<it>Mus domesticus</it>), where artificial ejaculation techniques have proven inadequate. Here we investigate an alternative method for identifying ejaculated proteins, by isotopically labeling females with ¹⁵N and then mating them to unlabeled, vasectomized males. Proteins were then isolated from mated females and identified using mass spectrometry. In addition to gaining insights into possible functions and fates of ejaculated proteins, our study serves as proof of concept that isotopic labeling is a powerful means to study reproductive proteins.</p> <p>Results</p> <p>We identified 69 male-derived proteins from the female reproductive tract following copulation. More than a third of all spectra detected mapped to just seven genes known to be structurally important in the formation of the copulatory plug, a hard coagulum that forms shortly after mating. Seminal fluid is significantly enriched for proteins that function in protection from oxidative stress and endopeptidase inhibition. Females, on the other hand, produce endopeptidases in response to mating. The 69 ejaculated proteins evolve significantly more rapidly than other proteins that we previously identified directly from dissection of the male reproductive tract.</p> <p>Conclusion</p> <p>Our study attempts to comprehensively identify the proteins transferred from males to females during mating, expanding the application of isotopic labeling to mammalian reproductive genomics. This technique opens the way to the targeted monitoring of the fate of ejaculated proteins as they incubate in the female reproductive tract.</p

精嚢分泌タンパク質によるマウス精子受精能獲得の制御機構に関する研究

学位の種別: 課程博士審査委員会委員 : (主査)東京大学准教授 吉田 学, 東京大学教授 岡 良隆, 東京大学成育医療室長 宮戸 健二, 東京大学准教授 朴 民根, 東京大学准教授 尾田 正二University of Tokyo(東京大学

Primate proteomic composition of seminal plasma and prostate-specific transglutaminase activity in relation to sexual selection.

Humans (Homo sapiens), chimpanzees (Pan troglodytes), and gorillas (Gorilla gorilla) have diverse mating systems with varying levels of sperm competition. Several seminal plasma genes have been claimed to evolve under positive selection, while others are altered or lost. This study aims to identify biologically relevant differences among seminal plasma proteomes of primates in relation to mating systems and previous genomic studies. Seminal plasma from three individuals of each species were run in triplicate in shotgun liquid chromatography – tandem mass spectrometry (LC-MS/MS) and confirmed with Western blots. Over 7,000 peptides were identified across all individuals; 168 proteins were identified with high confidence, 70 seminal plasma proteins were identified for human, 64 proteins for chimpanzee, and 34 proteins for gorilla. The gorilla seminal plasma proteome has higher variation among individuals and many proteins involved in semen coagulation and liquefaction have been lost. Chimpanzees have approximately 7-fold higher prostate specific transglutaminase (TGM4) expression than humans. TGM4 was not detected in gorillas, supporting pseudogenization of this gene. The structural semenogelin proteins, SEMG1 and SEMG2, were detected in high abundance in only one of three gorilla individuals, and in all three human and chimpanzee individuals. Chimpanzees have significantly higher expression of SEMG1 (~2.5-fold) compared to human; whereas, they only produce a small amount of SEMG2; ~6.5 –fold less than humans. Chimpanzees have roughly 34-fold higher expression of a serine protease inhibitor, SERPINA3 (Serpin Family A Member 3), than humans. SERPINA3 paralogs, SERPINA1 and SERPINA5, also have increased expression (~2.5 –fold) compared to human, and only SERPINA1 was detected in gorilla. SERPINAs may delay protease dissolution of the copulatory plug in chimpanzees. Recombinant human TGM4 and the reconstructed ancestral TGM4 sequence of our last common ancestor (LCA) with chimpanzees (the human-chimpanzee ancestor) proteins were produced and incubated with casein and monodansylcaverdine to determine enzymatic activity. The human-chimpanzee ancestor TGM4 had higher activity compared to human TGM4. Considering the importance of TGM4 in semen coagulation and copulatory plug formation in chimpanzee, the increased activity of the human-chimpanzee ancestor TGM4 may be indicative of elevated female promiscuity of our LCA, perhaps similar to a chimp-like mating system