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Characterization of CD46 and β 1 integrin dynamics during sperm acrosome reaction

View Article: PubMed Central - PubMed

ABSTRACT

The acrosome reaction (AR) is a process of membrane fusion and lytic enzyme release, which enables sperm to penetrate the egg surroundings. It is widely recognized that specific sperm proteins form an active network prior to fertilization, and their dynamic relocation is crucial for the sperm-egg fusion. The unique presence of the membrane cofactor protein CD46 in the sperm acrosomal membrane was shown, however, its behaviour and connection with other sperm proteins has not been explored further. Using super resolution microscopy, we demonstrated a dynamic CD46 reorganisation over the sperm head during the AR, and its interaction with transmembrane protein integrins, which was confirmed by proximity ligation assay. Furthermore, we propose their joint involvement in actin network rearrangement. Moreover, CD46 and β1 integrins with subunit α3, but not α6, are localized into the apical acrosome and are expected to be involved in signal transduction pathways directing the acrosome stability and essential protein network rearrangements prior to gamete fusion.

No MeSH data available.


The differences in the percentage distribution of sperm with intact acrosome, sperm with absent relocation and sperm with protein relocation patterns of CD46 and β1 integrin after the AR induction between the control samples and samples incubated with Latrunculin A.Error bars represent standard deviations. ***p ≤ 0.001.
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f9: The differences in the percentage distribution of sperm with intact acrosome, sperm with absent relocation and sperm with protein relocation patterns of CD46 and β1 integrin after the AR induction between the control samples and samples incubated with Latrunculin A.Error bars represent standard deviations. ***p ≤ 0.001.

Mentions: Latrunculin A, a toxin that binds to actin monomers and prevents them from polymerizing, significantly affected the ability of sperm to relocate both the CD46 and β1 integrin subunit when the acrosome reaction was induced (Fig. 9). The co-incubation of sperm with Latrunculin A followed by an induced AR led to a decrease of protein relocation of about 60% for CD46 and 40% for β1 integrin (Fig. 9). This compares to 90% positively relocated proteins in the control. There is also a significant difference in the percentages of sperm with a relocation pattern between CD46 and β1 integrin, where CD46 expresses a higher inhibition rate of the protein relocation compared to β1 integrin (significance indicators not shown in Fig. 9). Relevant control samples of sperm incubated with Latrunculin A and induced AR were run. The acrosome status was monitored by PNA lectin and there was near to zero blocking of the acrosome exocytosis caused by Latrunculin A (Fig. S5).


Characterization of CD46 and β 1 integrin dynamics during sperm acrosome reaction
The differences in the percentage distribution of sperm with intact acrosome, sperm with absent relocation and sperm with protein relocation patterns of CD46 and β1 integrin after the AR induction between the control samples and samples incubated with Latrunculin A.Error bars represent standard deviations. ***p ≤ 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036054&req=5

f9: The differences in the percentage distribution of sperm with intact acrosome, sperm with absent relocation and sperm with protein relocation patterns of CD46 and β1 integrin after the AR induction between the control samples and samples incubated with Latrunculin A.Error bars represent standard deviations. ***p ≤ 0.001.
Mentions: Latrunculin A, a toxin that binds to actin monomers and prevents them from polymerizing, significantly affected the ability of sperm to relocate both the CD46 and β1 integrin subunit when the acrosome reaction was induced (Fig. 9). The co-incubation of sperm with Latrunculin A followed by an induced AR led to a decrease of protein relocation of about 60% for CD46 and 40% for β1 integrin (Fig. 9). This compares to 90% positively relocated proteins in the control. There is also a significant difference in the percentages of sperm with a relocation pattern between CD46 and β1 integrin, where CD46 expresses a higher inhibition rate of the protein relocation compared to β1 integrin (significance indicators not shown in Fig. 9). Relevant control samples of sperm incubated with Latrunculin A and induced AR were run. The acrosome status was monitored by PNA lectin and there was near to zero blocking of the acrosome exocytosis caused by Latrunculin A (Fig. S5).

View Article: PubMed Central - PubMed

ABSTRACT

The acrosome reaction (AR) is a process of membrane fusion and lytic enzyme release, which enables sperm to penetrate the egg surroundings. It is widely recognized that specific sperm proteins form an active network prior to fertilization, and their dynamic relocation is crucial for the sperm-egg fusion. The unique presence of the membrane cofactor protein CD46 in the sperm acrosomal membrane was shown, however, its behaviour and connection with other sperm proteins has not been explored further. Using super resolution microscopy, we demonstrated a dynamic CD46 reorganisation over the sperm head during the AR, and its interaction with transmembrane protein integrins, which was confirmed by proximity ligation assay. Furthermore, we propose their joint involvement in actin network rearrangement. Moreover, CD46 and β1 integrins with subunit α3, but not α6, are localized into the apical acrosome and are expected to be involved in signal transduction pathways directing the acrosome stability and essential protein network rearrangements prior to gamete fusion.

No MeSH data available.