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Gene Sep 2013Mammalian fertilization is a complex process that involves gamete recognition, penetration, and fusion. Biochemical studies that identified the role of acrosome... (Review)
Review
Mammalian fertilization is a complex process that involves gamete recognition, penetration, and fusion. Biochemical studies that identified the role of acrosome components during sperm-ova interaction especially the zona pellucida (ZP) provided major advances in sperm cell biology. Acrosin (a typical serine protease) functions during fertilization in several significant ways which include: a) activation of acrosome components, b) secondary binding with the ZP, and c) hydrolysis of the ZP. However, studies using knockout (KO) acrosin-deficient mice cast doubt on the traditional role of acrosin in fertilization. The KO acrosin-deficient mice exhibit normal fecundity except for delayed fertilization. Despite the doubt cast on the traditional role of acrosin by the KO acrosin-deficient mouse studies, acrosin still remains a major protease involved in multiple processes of fertilization. In this review, we assess the functional profile of acrosin and briefly summarize recent findings on proteases involved in fertilization. We propose a refined scheme for the functional role of acrosin in fertilization. We particularly emphasize the role of acrosin in acrosome exocytosis and activation of other acrosome components based on advanced technology like structural X-ray analysis.
Topics: Acrosin; Acrosome; Acrosome Reaction; Animals; Female; Fertilization; Gene Knockout Techniques; Male; Mice; Sperm-Ovum Interactions; Zona Pellucida
PubMed: 23747402
DOI: 10.1016/j.gene.2013.05.058 -
Human Genetics Oct 1991The sperm enzyme acrosin has long been known as one of the key enzymes in the mammalian fertilization process. Elucidation of primary structures of preproacrosin from... (Review)
Review
The sperm enzyme acrosin has long been known as one of the key enzymes in the mammalian fertilization process. Elucidation of primary structures of preproacrosin from various species have allowed a deeper insight into the structural organization and the complex evolution of the sperm proteinase acrosin. In addition to the typical elements of serine proteases, the acrosin molecule possesses one novel domain that might convey DNA-binding properties.
Topics: Acrosin; Amino Acid Sequence; Animals; Humans; Male; Molecular Sequence Data; Sequence Alignment; Spermatozoa
PubMed: 1937464
DOI: 10.1007/BF00201716 -
Human Reproduction (Oxford, England) Jun 2023Does a homozygous nonsense mutation in ACR lead to total fertilization failure (TFF) resulting in male infertility in humans?
STUDY QUESTION
Does a homozygous nonsense mutation in ACR lead to total fertilization failure (TFF) resulting in male infertility in humans?
SUMMARY ANSWER
A novel homozygous nonsense mutation of ACR (c.167G>A, p.Trp56X) was identified in two infertile brothers and shown to cause human TFF.
WHAT IS KNOWN ALREADY
ACROSIN, encoded by ACR, is a major acrosomal enzyme expressed only in the acrosome of the sperm head. Inhibition of acrosin prevents sperm penetration of the zona pellucida (ZP) in several species, including humans. Acr-knockout in hamsters causes male infertility with completely blocked fertilization. Of note, there are no reports of ACR mutations associated with TFF in humans.
STUDY DESIGN, SIZE, DURATION
Whole-exome sequencing (WES) was used for the identification of pathogenic genes for male factor TFF in eight involved couples.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Data from eight infertile couples who had experienced TFF during their IVF or ICSI attempts were collected. Functional assays were used to verify the pathogenicity of the potential genetic factors identified by WES. Subzonal insemination (SUZI) and IVF assays were performed to determine the exact pathogenesis of TFF caused by deficiencies in ACROSIN.
MAIN RESULTS AND THE ROLE OF CHANCE
A novel homozygous nonsense mutation in ACR, c.167G>A, p.Trp56X, was identified in two additional primary infertile brothers whose parents were first cousins. This rare mutation caused ACROSIN deficiency and acrosomal ultrastructural defects in the affected sperm. Spermatozoa lacking ACROSIN were unable to penetrate the ZP, rather than hampering sperm binding, disrupting gamete fusion, or preventing oocyte activation. These findings were supported by the fertilization success of SUZI and ICSI attempts, as well as the normal expression of ACTL7A and PLCζ in the mutant sperm, suggesting that ICSI without remedial assisted oocyte activation is an optimal treatment for ARCOSIN-deficient TFF.
LIMITATIONS, REASONS FOR CAUTION
The absence of another independent pedigree to support our argument is a limitation of this study.
WIDER IMPLICATIONS OF THE FINDINGS
The findings expand our understanding of the genes involved in human TFF, providing information for appropriate genetic counseling and fertility guidance for these patients.
STUDY FUNDING/COMPETING INTEREST(S)
This study was supported by the National Natural Science Foundation of China (grant no. 82201803, 81901541, 82271639, and 32000584), University Synergy Innovation Program of Anhui Province (GXXT-2019-044), and the Nonprofit Central Research Institute Fund of the Chinese Academy of Medical Sciences (grant no. 2019PT310002). The authors declare no conflicts of interest.
TRIAL REGISTRATION NUMBER
N/A.
Topics: Animals; Cricetinae; Humans; Male; Acrosin; Zona Pellucida; Codon, Nonsense; Semen; Spermatozoa; Sperm-Ovum Interactions; Infertility, Male
PubMed: 37004249
DOI: 10.1093/humrep/dead059 -
Proceedings of the National Academy of... Feb 2020During natural fertilization, mammalian spermatozoa must pass through the zona pellucida before reaching the plasma membrane of the oocyte. It is assumed that this step...
During natural fertilization, mammalian spermatozoa must pass through the zona pellucida before reaching the plasma membrane of the oocyte. It is assumed that this step involves partial lysis of the zona by sperm acrosomal enzymes, but there has been no unequivocal evidence to support this view. Here we present evidence that acrosin, an acrosomal serine protease, plays an essential role in sperm penetration of the zona. We generated acrosin-knockout (KO) hamsters, using an in vivo transfection CRISPR/Cas9 system. Homozygous mutant males were completely sterile. Acrosin-KO spermatozoa ascended the female genital tract and reached ovulated oocytes in the oviduct ampulla, but never fertilized them. In vitro fertilization (IVF) experiments revealed that mutant spermatozoa attached to the zona, but failed to penetrate it. When the zona pellucida was removed before IVF, all oocytes were fertilized. This indicates that in hamsters, acrosin plays an indispensable role in allowing fertilizing spermatozoa to penetrate the zona. This study also suggests that the KO hamster system would be a useful model for identifying new gene functions or analyzing human and animal disorders because of its technical facility and reproducibility.
Topics: Acrosin; Acrosome; Animals; Cricetinae; Female; Fertilization in Vitro; Gene Knockout Techniques; Male; Sperm-Ovum Interactions; Spermatozoa; Zona Pellucida
PubMed: 31964830
DOI: 10.1073/pnas.1917595117 -
The American Journal of Physiology Jul 1979Mouse spermatozoa possess a neutral proteinase, acrosin, that is to a large extent (70-80%) present in the zymogen (proacrosin) form. Acid extraction yields higher...
Mouse spermatozoa possess a neutral proteinase, acrosin, that is to a large extent (70-80%) present in the zymogen (proacrosin) form. Acid extraction yields higher amounts of acrosin than detergent extraction. Synthetic inhibitor studies indicate that mouse acrosin has a serine and histidine at its active site and hydrolyzes the peptide bonds of lysine and arginine but of not phenylalanine. An inhibitor of acrosin is associated with mouse spermatozoa, capable of preventing the activity of at least 60% of all available acrosin. Acrosin activity is essential for fertilization because natural and synthetic inhibitors of mouse acrosin prevent the union of the gametes. Also, the relative inhibitory activity of synthetic agents toward acrosin runs approximately parallel to their antifertility activity. The percent of acrosin in the proacrosin form does not change after capacitating mouse spermatozoa in vitro.
Topics: Acrosin; Animals; Arginine; Benzamidines; Endopeptidases; Enzyme Inhibitors; Fertilization; Lysine; Male; Mice; Polyethylene Glycols; Sperm Capacitation; Spermatozoa
PubMed: 464051
DOI: 10.1152/ajpendo.1979.237.1.E40 -
The International Journal of... 1979
Review
Topics: Acrosin; Animals; Endopeptidases; Enzyme Precursors; Male; Sperm Head; Spermatozoa
PubMed: 383541
DOI: 10.1016/0020-711x(79)90061-2 -
Methods in Enzymology 1981
Comparative Study
Topics: Acrosin; Amino Acid Sequence; Animals; Endopeptidases; Humans; Male; Molecular Weight; Sheep; Species Specificity; Spermatozoa; Swine
PubMed: 7043204
DOI: 10.1016/s0076-6879(81)80049-3 -
Methods in Enzymology 1976
Topics: Acrosin; Amino Acids; Animals; Chromatography, Affinity; Endopeptidases; Esterases; Humans; Male; Methods; Species Specificity; Spermatozoa; Swine
PubMed: 1012001
DOI: 10.1016/s0076-6879(76)45030-9 -
Differentiation; Research in Biological... 1983Using the indirect immunofluorescence staining technique, the developmental pattern of acrosin during spermatogenesis of boar, ram, rabbit, mouse, rat, and Russian...
Using the indirect immunofluorescence staining technique, the developmental pattern of acrosin during spermatogenesis of boar, ram, rabbit, mouse, rat, and Russian hamster (Phodopus sungorus) was studied. Specific antibodies against purified boar acrosin raised in rabbits cross-reacted with the acrosin of all species investigated thus suggesting that the antigenic determinants of the acrosin molecule cross-reacting with anti-boar acrosin antiserum have been highly conserved in mammalian evolution. During spermatogenesis acrosin was first demonstrable in haploid spermatids and increased in the course of the differentiation of the spermatids to spermatozoa. During the entire period of spermatid differentiation acrosin appeared in juxtaposition to the nucleus. In boar and ram the results obtained with the indirect immunofluorescence staining procedure were confirmed with the indirect immunoperoxidase staining method.
Topics: Acrosin; Animals; Cell Differentiation; Cricetinae; Endopeptidases; Fluorescent Antibody Technique; Immunoenzyme Techniques; Male; Mice; Rabbits; Rats; Sheep; Spermatids; Spermatogenesis; Spermatozoa; Swine; Testis
PubMed: 6354818
DOI: 10.1111/j.1432-0436.1983.tb01328.x -
Interactions between zona pellucida glycoproteins and sperm proacrosin/acrosin during fertilization.Journal of Reproductive Immunology Jan 2002Fertilization is one of the most specific and carefully regulated cell-cell interactions in the animal body and is determined to a large extent by compatibility between... (Review)
Review
Fertilization is one of the most specific and carefully regulated cell-cell interactions in the animal body and is determined to a large extent by compatibility between ligand and receptor molecules on the surface of each gamete. On the zona pellucida (ZP), sperm receptor activity is associated with glycoproteins ZP3 (primary receptor for acrosome-intact sperm) and ZP2 (secondary receptor for acrosome-reacted sperm) but their complementary binding proteins on sperm are less well defined. In this communication we review the evidence for proacrosin as a secondary ZP binding protein. Proacrosin/acrosin binds non-enzymically to ZP glycoproteins. Binding is a strong ionic interaction between polysulphate groups on ZP glycoproteins (probably on their carbohydrate moieties) and basic residues on the surface of proacrosin. The stereochemistry of the reactants is crucial and determines to a large extent the affinity of binding. Site-directed mutagenesis and a 3D-structural analysis of boar and ram acrosin have identified 2 clusters of basic residues potentially involved in binding. A polysulphonated anticancer drug, suramin, has been shown to bind strongly to proacrosin/acrosin and to inhibit sperm-egg binding in vitro. In the mouse model, 125I-ZP2 and 3H-suramin bind approximately 65% less effectively to acrosin 'null' sperm than to wild-type sperm. Neither ZP2 nor suramin bind to acrosome intact sperm and can, therefore, only exert their effects after exposure of the acrosomal contents. Overall, this combination of biochemical, genetic and functional data supports the hypothesis that proacrosin is a multifunctional protein with a significant role in retaining acrosome-reacted sperm on the ZP surface long enough to enable ZP penetration to begin.
Topics: Acrosin; Animals; Binding Sites; Egg Proteins; Enzyme Precursors; Female; In Vitro Techniques; Ligands; Male; Membrane Glycoproteins; Models, Biological; Mutagenesis, Site-Directed; Protein Binding; Receptors, Cell Surface; Sperm-Ovum Interactions; Suramin; Zona Pellucida Glycoproteins
PubMed: 11730915
DOI: 10.1016/s0165-0378(01)00101-2