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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.


Statistical analysis of the relocation process.(A) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 sperm with an intact acrosome. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). (B) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 acrosome reacted sperm. (C) Statistical comparison of the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among individual segments of the sperm head between the acrosome-intact and acrosome-reacted sperm. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). Error bars denote SEM. AC – Acrosome Cap, ES – Equatorial Segment, PAR – Post-Acrosomal Region. p value equal or lower than 0.05 was considered to be significant, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001.
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f3: Statistical analysis of the relocation process.(A) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 sperm with an intact acrosome. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). (B) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 acrosome reacted sperm. (C) Statistical comparison of the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among individual segments of the sperm head between the acrosome-intact and acrosome-reacted sperm. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). Error bars denote SEM. AC – Acrosome Cap, ES – Equatorial Segment, PAR – Post-Acrosomal Region. p value equal or lower than 0.05 was considered to be significant, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001.

Mentions: To analyse the distribution of individual CD46 and β1 integrin relocation patterns, among groups with different times of capacitation followed by the induced AR, the depicted protein patterns were placed beside each other (Fig. 2). The proteins behaviour was shown to be similar. This was further confirmed by the statistical analysis of fluorescent intensities, which depicted fluorescent signal differences between protein distribution in intact acrosome and in acrosome reacted sperm (Fig. 3). Both analyses are described in the following chapter.


Characterization of CD46 and β 1 integrin dynamics during sperm acrosome reaction
Statistical analysis of the relocation process.(A) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 sperm with an intact acrosome. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). (B) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 acrosome reacted sperm. (C) Statistical comparison of the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among individual segments of the sperm head between the acrosome-intact and acrosome-reacted sperm. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). Error bars denote SEM. AC – Acrosome Cap, ES – Equatorial Segment, PAR – Post-Acrosomal Region. p value equal or lower than 0.05 was considered to be significant, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Statistical analysis of the relocation process.(A) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 sperm with an intact acrosome. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). (B) Coloured lines with error bars represent the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among the individual segments of the sperm head in 10 acrosome reacted sperm. (C) Statistical comparison of the relative fluorescent intensities of β1 integrin (red) and CD46 (green) among individual segments of the sperm head between the acrosome-intact and acrosome-reacted sperm. Horizontal coloured lines represent the arithmetic means of the fluorescent intensities for β1 integrin (red) and CD46 (green). Error bars denote SEM. AC – Acrosome Cap, ES – Equatorial Segment, PAR – Post-Acrosomal Region. p value equal or lower than 0.05 was considered to be significant, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001.
Mentions: To analyse the distribution of individual CD46 and β1 integrin relocation patterns, among groups with different times of capacitation followed by the induced AR, the depicted protein patterns were placed beside each other (Fig. 2). The proteins behaviour was shown to be similar. This was further confirmed by the statistical analysis of fluorescent intensities, which depicted fluorescent signal differences between protein distribution in intact acrosome and in acrosome reacted sperm (Fig. 3). Both analyses are described in the following chapter.

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.