scholarly journals Sperm IZUMO1 Is Required for Binding Preceding Fusion With Oolemma in Mice and Rats

2022 ◽  
Vol 9 ◽  
Author(s):  
Takafumi Matsumura ◽  
Taichi Noda ◽  
Yuhkoh Satouh ◽  
Akane Morohoshi ◽  
Shunsuke Yuri ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Zona Pellucida ◽  
Knockout Mice ◽  
Knockout Mouse ◽  
Acrosome Reaction ◽  
Male Rats ◽  
Sperm Protein ◽  
Complex Processes ◽  
Sperm Binding ◽  
Mammalian Spermatozoa

Fertilization occurs as the culmination of multi-step complex processes. First, mammalian spermatozoa undergo the acrosome reaction to become fusion-competent. Then, the acrosome-reacted spermatozoa penetrate the zona pellucida and adhere to and finally fuse with the egg plasma membrane. IZUMO1 is the first sperm protein proven to be essential for sperm-egg fusion in mammals, as Izumo1 knockout mouse spermatozoa adhere to but fail to fuse with the oolemma. However, the IZUMO1 function in other species remains largely unknown. Here, we generated Izumo1 knockout rats by CRISPR/Cas9 and found the male rats were infertile. Unlike in mice, Izumo1 knockout rat spermatozoa failed to bind to the oolemma. Further investigation revealed that the acrosome-intact sperm binding conceals a decreased number of the acrosome-reacted sperm bound to the oolemma in Izumo1 knockout mice. Of note, we could not see any apparent defects in the binding of the acrosome-reacted sperm to the oolemma in the mice lacking recently found fusion-indispensable genes, Fimp, Sof1, Spaca6, or Tmem95. Collectively, our data suggest that IZUMO1 is required for the sperm-oolemma binding prior to fusion at least in rat.

scholarly journals The sperm protein SPACA4 is required for efficient fertilization in mice

2021 ◽  
Author(s):  
Sarah Herberg ◽  
Yoshitaka Fujihara ◽  
Andreas Blaha ◽  
Karin Panser ◽  
Kiyonari Kobayashi ◽  
...  
Keyword(s):  
Zona Pellucida ◽  
Knockout Mice ◽  
Mammalian Species ◽  
Wild Type ◽  
Sperm Protein ◽  
Mammalian Sperm ◽  
Fundamental Process ◽  
Mammalian Fertilization

Fertilization is the fundamental process that initiates the development of a new individual in all sexually reproducing species. Despite its importance, our understanding of the molecular players that govern mammalian sperm-egg interaction is incomplete, partly because many of the essential factors found in non-mammalian species do not have obvious mammalian homologs. We have recently identified the Ly6/uPAR protein Bouncer as a new, essential fertilization factor in zebrafish (Herberg et al., 2018). Here, we show that Bouncer's homolog in mammals, SPACA4, is also required for efficient fertilization in mice. In contrast to fish, where Bouncer is expressed specifically in the egg, SPACA4 is expressed exclusively in the testis. Male knockout mice are severely sub-fertile, and sperm lacking SPACA4 fail to fertilize wild-type eggs in vitro. Interestingly, removal of the zona pellucida rescues the fertilization defect of Spaca4-deficient sperm in vitro, indicating that SPACA4 is not required for the interaction of sperm and the oolemma but rather of sperm and zona pellucida. Our work identifies SPACA4 as an important sperm protein necessary for zona pellucida penetration during mammalian fertilization.

Functional interactions between sulphated polysaccharides and proacrosin: implications in sperm binding and digestion of zona pellucida

Zygote ◽  
1999 ◽  
Vol 7 (2) ◽  
pp. 105-111 ◽  
Author(s):  
R. D. Moreno ◽  
M. Hoshi ◽  
C. Barros
Keyword(s):  
Zona Pellucida ◽  
Active Site ◽  
Acrosome Reaction ◽  
Penetration Rate ◽  
Limited Proteolysis ◽  
Sulphated Polysaccharides ◽  
Functional Interactions ◽  
Sperm Binding ◽  
Sperm Penetration ◽  
Sperm Acrosome Reaction

Acrosin is a serine protease located within mammalian acrosome as inactive proacrosin. Sulphated polymers bind to proacrosin and acrosin, to a domain different from the active site. Upon binding, these polymers induce proacrosin activation and some of them, such as fucoidan, inhibit sperm binding to the zona pellucida. In this work we have studied the interaction of solubilised zona pellucida glycoproteins (ZPGs), heparin and ARIS (Acrosome Reaction Inducing Substance of Starfish) with boar and human acrosin. We have found that ARIS, solubilised ZPGs and fucoidan, but not heparin, inhibit the binding of the monoclonal antibody against human acrosin C5F10 to boar or human proacrosin. These results suggest that fucoidan, solubilised ZPGs and ARIS bind to a related domain on the proacrosin surface. Moreover, ARIS was able to induce human proacrosin activation. On the other hand, neither ARIS nor heparin from porcine intestinal mucosa or bovine lung induced hamster sperm acrosome reaction or sperm motility. Recent data showed that acrosin is involved in dispersal of the acrosomal matrix after acrosome reaction. Thus, the control of the ZPG glycan chains over proacrosin activation may regulate both sperm penetration rate and limited proteolysis of zona pellucida proteins.

Hyaluronic acid and the cumulus extracellular matrix induce increases in intracellular calcium in macaque sperm via the plasma membrane protein PH-20

Zygote ◽  
1999 ◽  
Vol 7 (3) ◽  
pp. 211-222 ◽  
Author(s):  
Gary N. Cherr ◽  
Ashley I. Yudin ◽  
Ming-Wen Li ◽  
Carol A. Vines ◽  
James W. Overstreet
Keyword(s):  
Extracellular Matrix ◽  
Plasma Membrane ◽  
Hyaluronic Acid ◽  
Zona Pellucida ◽  
Cynomolgus Macaque ◽  
Fluorescein Isothiocyanate ◽  
Positive Control ◽  
Fab Fragments ◽  
Sperm Binding ◽  
Intracellular Ca

The hyaluronic acid (HA)-rich extracellular matrix (ECM) of the cumulus oophorus is known to facilitate fertilisation. It has been suggested that HA may enhance fertilisation in a number of species, and in macaque sperm, HA has been shown to increase the number of acrosome reactions that follow sperm binding to the zona pellucida. In this study, we investigated the effects of HA on intracellular Ca2+ in capacitated cynomolgus macaque sperm. Fluorometry studies using the intracellular Ca2+ indicator Fluo-3 showed that addition of 100 μg/ml of HA induced a rapid increase in intracellular Ca2+. This Ca2+ increase (approximately 2–3 times above basal levels) was inhibited by preincubation of sperm with Fab fragments of anti-recombinant PH-20 IgG. The frequency of acrosome reactions in sperm exposed to HA was not above control levels. A synthetic gel was prepared with similar viscosity to the cumulus and with HA trapped in its matrix. Video imaging of individual sperm was used to demonstrate that capacitated sperm swimming into the HA gel had increased intracellular Ca2+ levels. Preincubation of sperm with Fab fragments of anti-PH-20 IgG inhibited the increased intracellular Ca2+ levels induced by the HA gel. Sperm in control gel (no HA) did not show increased intracellular Ca2+, while sperm in gel containing anti-PH-20 IgG showed increased Ca2+ (positive control). Sperm loaded with Fluo-3 were allowed to interact with cynomologus macaque cumulus masses, and sperm within the cumulus ECM clearly showed increased intracellular Ca2+ that was inhibited when sperm were preincubated in anti-PH-20 Fab. Fluorescein isothiocyanate (FITC)-HA was found to bind to sperm over the acrosomal region, corresponding to PH-20 localisation, and this binding could be inhibited by preincubation of sperm with anti-PH-20 fragments. The results of this study show that HA increases intracellular Ca2+ in macaque sperm through interaction with plasma membrane PH-20. We propose that HA binding to plasma membrane PH-20 induces an aggregation of receptors that in turn results in intracellular signalling. As a result, sperm have higher basal CA2+ levels and are more responsive to induction of the acrosome reaction after binding to the zona pellucida.

Interaction of mouse sperm with purified sperm receptors covalently linked to silica beads

1989 ◽  
Vol 92 (4) ◽  
pp. 713-722
Author(s):  
M.H. Vazquez ◽  
D.M. Phillips ◽  
P.M. Wassarman
Keyword(s):  
Zona Pellucida ◽  
Acrosome Reaction ◽  
Solid Phase ◽  
Galactose Oxidase ◽  
Flow Cytofluorometry ◽  
Mouse Sperm ◽  
Sperm Binding ◽  
Silica Beads ◽  
Covalently Linked ◽  
Solid Phase Assay

We describe a solid-phase assay that has permitted further analysis of zona pellucida glycoprotein, ZP3, as sperm receptor and acrosome reaction-inducer during fertilization in mice. The assay employs silica beads that contain epoxy groups to which purified, mouse oocyte ZP3 is covalently linked (ZP3-beads). ZP3-beads were characterized, e.g. by whole-mount autoradiography and flow cytofluorometry, incubated with capacitated mouse sperm under a variety of conditions, and the extent of sperm binding determined by light microscopy. Results of experiments presented suggest the following: (1) sperm bind specifically to ZP3-beads, but not to silica beads either exposed to 2-aminoethanol or derivatized with oocyte ZP2, fetuin or bovine serum albumin. (2) In nearly all cases, only one sperm binds per ZP3-bead and binding occurs via the sperm head. (3) The extent of sperm binding to ZP3-beads is dependent on ZP3 and sperm concentrations, as well as on incubation time and temperature. (4) Sperm binding to ZP3-beads is unaffected by antibodies directed against ZP3, but is inhibited in a reversible manner by treatment of ZP3-beads with galactose oxidase. (5) Only acrosome-intact sperm bind to ZP3-beads but, once bound, sperm can undergo the acrosome reaction, which results in their release from ZP3-beads. (6) Islet-activating protein and 3-quinuclidinyl benzilate, two inhibitors of the zona pellucida-induced acrosome reaction, prevent sperm bound to ZP3-beads from undergoing the acrosome reaction. These results confirm and extend previous studies of sperm-egg interaction in mice, and suggest that the solid-phase assay will be useful for both cellular and biochemical analyses of mammalian fertilization.

scholarly journals Rab27b Is Expressed in a Wide Range of Exocytic Cells and Involved in the Delivery of Secretory Granules Near the Plasma Membrane

2007 ◽  
Vol 18 (11) ◽  
pp. 4377-4386 ◽  
Author(s):  
Hiroshi Gomi ◽  
Kenichi Mori ◽  
Shigeyoshi Itohara ◽  
Tetsuro Izumi
Keyword(s):  
Plasma Membrane ◽  
Knockout Mice ◽  
Secretory Granules ◽  
Secretory Cells ◽  
Rab Proteins ◽  
Double Knockout ◽  
Surface Protection ◽  
Complex Processes ◽  
Wide Range ◽  
Targeting Vector

Rab proteins regulate multiple, complex processes of membrane traffic. Among these proteins, Rab27a has been shown to function specifically in regulated exocytic pathways. However, the roles of Rab27b, another Rab27 subfamily member, have not been well characterized. We disrupted the Rab27b gene in mice. The targeting vector was designed to insert LacZ downstream of the initiation codon of the Rab27b gene so that the authentic promoter should drive this reporter gene. A comprehensive analysis of Rab27b expression using this mouse strain indicated that it is widely expressed not only in canonical secretory cells, but also in neurons and cells involved in surface protection and mechanical extension. To evaluate the function in pituitary endocrine cells where the isoform Rab27a is coexpressed, we generated Rab27a/Rab27b double knockout mice by crossing Rab27b knockout mice with Rab27a-mutated ashen mice. The polarized distribution of secretory granules close to the plasma membrane was markedly impaired in the pituitary of double knockout mice, indicating that the Rab27 subfamily is involved in the delivery of granules near the exocytic site. In conjunction with a phenotype having a pituitary devoid of the Rab27 effector granuphilin, we discuss the relationship between the residence and the releasable pool of granules.

Evidence that acrosin activity is important for the development of fusibility of mammalian spermatozoa with the oolemma: inhibitor studies using the golden hamster

Zygote ◽  
1993 ◽  
Vol 1 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Hiroko Takano ◽  
R. Yanagimachi ◽  
Umbert A. Urch
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Free Medium ◽  
Inhibitory Effects ◽  
Chloromethyl Ketone ◽  
Gamete Fusion ◽  
Sperm Plasma Membrane ◽  
Acrosomal Enzyme ◽  
Acrosin Activity ◽  
Mammalian Spermatozoa

SummaryThe sperm plasma membrane over the equatorial segment of the acrosome gains the ability to fuse with the oolemma some time during, or after, the acrosome reaction. Since acrosin is a major component of the acrosome matrix that dissolves during the acrosome reaction, we sought to determine the effect of acrosin inhibitors on the sperm's ability to fuse with the oolemma. Five acrosin inhibitors (soybean trypsin inhibitor (SBTI), leupeptin, benzamidine, N-p-tosyl-1-lysin-chloromethyl ketone (TLCK) and phenylmethylsulphonyl fluoride (PMSF) and one non-acrosin inhibitor (N-p-tosyl-1-phenylalanine chloromethyl ketone (TPCK) were tested at non-toxic levels (below motility-disturbing concentrations). These inhibitors were added at three different times: (1) during the acrosome reaction of spermatozoa, (2) during sperm-oocyte contact and fusion, and (3) soon after sperm-oocyte fusion was completed. TLCK prevented sperm-oocyte fusion by inhibiting the acrosome reaction.PMSF inhibited gamete fusion, without inhibiting the acrosome reaction. SBTI, leupeptin and benzamidine also inhibited gamete fusion, but they had no effect if spermatozoa were allowed to acrosome-react in inhibitor-free medium. TPCK was without any inhibitory effects, suggesting that chymotrypsin-like enzymes are not involved in gamete fusion. Although acrosin inhibitors prevented acrosome-reacted spermatozoa from becoming fusion-competent, acrosin (and trypsin) alone could not make the plasma membrane of acrosome-intact spermatozoa fusion-competent. The data suggest that (1) the plasma membrane of the acrosomal region first undergoes dramatic changes immediately before or during the acrosome reaction and (2) acrosin released from the acrosome during the acrosome reaction further alters biophysical and biochemical characteristics of the plasma membrane over the equatorial segment. Such dual changes make the plasma membrane of this specialised region of the spermatozoon competent to fuse with the oolemma. Acrosin may not be the only acrosomal enzyme to participate in these changes.

scholarly journals Could multiple low-affinity bonds mediate primary sperm-zona pellucida binding?

Reproduction ◽  
2002 ◽  
pp. 29-32 ◽  
Author(s):  
PE Castle
Keyword(s):  
Cell Surface ◽  
Zona Pellucida ◽  
Current Model ◽  
Sperm Protein ◽  
High Affinity ◽  
Sperm Binding ◽  
Specific Manner ◽  
Motile Spermatozoon ◽  
A Cell

The current model for primary sperm binding to the zona pellucida is that a cell-surface sperm protein binds with high affinity in an order-specific manner to one of the zona pellucida proteins, ZP3. However, the molecular details of primary sperm-zona pellucida binding remain elusive. A possible revised model is that multiple low-affinity bonds between spermatozoa and the zona pellucida may be sufficient for primary binding. The avidity of several low-affinity bonds can exceed that of a single high-affinity bond, which is sufficient to tether a motile spermatozoon. A mechanism involving multiple low-affinity bonds could account for some of the difficulties in elucidating primary sperm-zona pellucida interactions.

scholarly journals Mouse gamete interactions during fertilization in vitro. Chlortetracycline as a fluorescent probe for the mouse sperm acrosome reaction.

1979 ◽  
Vol 83 (3) ◽  
pp. 544-555 ◽  
Author(s):  
P M Saling ◽  
B T Storey
Keyword(s):  
Plasma Membrane ◽  
Fluorescent Probe ◽  
Zona Pellucida ◽  
Acrosome Reaction ◽  
Sperm Head ◽  
Fertilization In Vitro ◽  
Ionophore A23187 ◽  
Mouse Sperm ◽  
Sperm Acrosome

We have developed an assay for detecting the acrosome reaction in mouse sperm using chlortetracycline (CTC) as a fluorescent probe. Sperm known to be intact with nonreacted acrosomes show CTC fluorescence in the presence of Ca2+ over the anterior portion of the sperm head on the plasma membrane covering the acrosome. Sperm which have undergone the acrosome reaction do not show fluorescence on the sperm head. Mouse sperm bind to zonae pellucidae of cumulus-free eggs in vitro in a Ca2+-dependent reaction; these sperm are intact by the CTC assay. Intact sperm bind to mechanically isolated zonae under the same conditions: the egg is apparently unnecessary for this inital reaction. Sperm suspensions, in which greater than 50% of the motile population had completed the acrosome reaction, were prepared by incubation in hyperosmolal medium followed by treatment with the divalent cation ionophore, A23187. Cumulus-free eggs challenged with such sperm suspensions preferentially bind intact sperm; acrosome-reacted sperm do not bind. We conclude that the plasma membrane of the mouse sperm is responsible for recognition of the egg's zona pellucida and that the obligatory sequence of reactions leading to fusion of mouse gametes is binding of the intact sperm to the zona pellucida, followed by the acrosome reaction at the zona surface, followed in turn by sperm penetration of the zona.

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