Limits...
A role for the disintegrin domain of cyritestin, a sperm surface protein belonging to the ADAM family, in mouse sperm-egg plasma membrane adhesion and fusion.

Yuan R, Primakoff P, Myles DG - J. Cell Biol. (1997)

Bottom Line: This protein family has been named ADAM because all members contain a disintegrin and metalloprotease domain.Full length cDNA clones have been isolated for five ADAMs expressed in mouse testis: fertilin alpha, fertilin beta, cyritestin, ADAM 4, and ADAM 5.Characterization of these two ADAM family members showed that they are both processed during sperm maturation and present on mature sperm.

View Article: PubMed Central - PubMed

Affiliation: Molecular and Cellular Biology, University of California, Davis 95616, USA.

ABSTRACT
Sperm-egg plasma membrane fusion is preceded by sperm adhesion to the egg plasma membrane. Cell-cell adhesion frequently involves multiple adhesion molecules on the adhering cells. One sperm surface protein with a role in sperm-egg plasma membrane adhesion is fertilin, a transmembrane heterodimer (alpha and beta subunits). Fertilin alpha and beta are the first identified members of a new family of membrane proteins that each has the following domains: pro-, metalloprotease, disintegrin, cysteine-rich, EGF-like, transmembrane, and cytoplasmic domain. This protein family has been named ADAM because all members contain a disintegrin and metalloprotease domain. Previous studies indicate that the disintegrin domain of fertilin beta functions in sperm-egg adhesion leading to fusion. Full length cDNA clones have been isolated for five ADAMs expressed in mouse testis: fertilin alpha, fertilin beta, cyritestin, ADAM 4, and ADAM 5. The presence of the disintegrin domain, a known integrin ligand, suggests that like fertilin beta, other testis ADAMs could be involved in sperm adhesion to the egg membrane. We tested peptide mimetics from the predicted binding sites in the disintegrin domains of the five testis-expressed ADAMs in a sperm-egg plasma membrane adhesion and fusion assay. The active site peptide from cyritestin strongly inhibited (80-90%) sperm adhesion and fusion and was a more potent inhibitor than the fertilin beta active site peptide. Antibodies generated against the active site region of either cyritestin or fertilin beta also strongly inhibited (80-90%) both sperm-egg adhesion and fusion. Characterization of these two ADAM family members showed that they are both processed during sperm maturation and present on mature sperm. Indirect immunofluorescence on live, acrosome-reacted sperm using antibodies against either cyritestin or fertilin beta showed staining of the equatorial region, a region of the sperm membrane that participates in the early steps of membrane fusion. Collectively, these data indicate that a second ADAM family member, cyritestin, functions with fertilin beta in sperm-egg plasma membrane adhesion leading to fusion.

Show MeSH

Related in: MedlinePlus

Effects of ADAM active site peptides on sperm–egg binding and fusion. Both experimental (A) and control (B) peptides were  tested at 500 μM. FI, fertilization index; FR, fertilization rate. The number of eggs tested for each peptide was between 43 and 82. For  the controls without peptides, 292 eggs were tested; the average number of sperm bound per egg was 11.6; the FR was 88.4%, and the FI  was 1.17. The sequences of each peptide are under their names. Error bars represent SEM. □, Percentage inhibition of binding; ▪, percentage inhibition of FI; ▨ , percentage inhibition of FR.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2139869&req=5

Figure 2: Effects of ADAM active site peptides on sperm–egg binding and fusion. Both experimental (A) and control (B) peptides were tested at 500 μM. FI, fertilization index; FR, fertilization rate. The number of eggs tested for each peptide was between 43 and 82. For the controls without peptides, 292 eggs were tested; the average number of sperm bound per egg was 11.6; the FR was 88.4%, and the FI was 1.17. The sequences of each peptide are under their names. Error bars represent SEM. □, Percentage inhibition of binding; ▪, percentage inhibition of FI; ▨ , percentage inhibition of FR.

Mentions: The mouse fertilin β peptide inhibited sperm–egg fusion (Fig. 2 A), as expected from previous work with guinea pig fertilin β peptides (Myles et al., 1994) and mouse fertilin β peptides (Almeida et al., 1995; Evans et al., 1995). The fertilin β peptide gave a 59% inhibition in FI and a 55% inhibition of FR, but only a slight inhibition of sperm–egg binding (13%; Fig. 2 A). The cyritestin peptide inhibited sperm–egg fusion more strongly than the fertilin β peptide and additionally inhibited sperm binding to the egg plasma membrane (Fig. 2 A). The peptide from cyritestin resulted in 84% inhibition of sperm–egg binding, 93% inhibition of the FI, and 92% inhibition of the FR. The fertilin α peptide showed limited inhibition (∼30%) of sperm–egg binding and fusion. Whether or not this is biologically significant is not yet clear. In comparison, the other two family members, ADAM 4 and 5 peptides, showed essentially no inhibition (Fig. 2 A). The control peptides for all of the five proteins, which contained the same eight amino acids but in a rearranged (scrambled) order, showed only slight or no inhibition (Fig. 2 B).


A role for the disintegrin domain of cyritestin, a sperm surface protein belonging to the ADAM family, in mouse sperm-egg plasma membrane adhesion and fusion.

Yuan R, Primakoff P, Myles DG - J. Cell Biol. (1997)

Effects of ADAM active site peptides on sperm–egg binding and fusion. Both experimental (A) and control (B) peptides were  tested at 500 μM. FI, fertilization index; FR, fertilization rate. The number of eggs tested for each peptide was between 43 and 82. For  the controls without peptides, 292 eggs were tested; the average number of sperm bound per egg was 11.6; the FR was 88.4%, and the FI  was 1.17. The sequences of each peptide are under their names. Error bars represent SEM. □, Percentage inhibition of binding; ▪, percentage inhibition of FI; ▨ , percentage inhibition of FR.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139869&req=5

Figure 2: Effects of ADAM active site peptides on sperm–egg binding and fusion. Both experimental (A) and control (B) peptides were tested at 500 μM. FI, fertilization index; FR, fertilization rate. The number of eggs tested for each peptide was between 43 and 82. For the controls without peptides, 292 eggs were tested; the average number of sperm bound per egg was 11.6; the FR was 88.4%, and the FI was 1.17. The sequences of each peptide are under their names. Error bars represent SEM. □, Percentage inhibition of binding; ▪, percentage inhibition of FI; ▨ , percentage inhibition of FR.
Mentions: The mouse fertilin β peptide inhibited sperm–egg fusion (Fig. 2 A), as expected from previous work with guinea pig fertilin β peptides (Myles et al., 1994) and mouse fertilin β peptides (Almeida et al., 1995; Evans et al., 1995). The fertilin β peptide gave a 59% inhibition in FI and a 55% inhibition of FR, but only a slight inhibition of sperm–egg binding (13%; Fig. 2 A). The cyritestin peptide inhibited sperm–egg fusion more strongly than the fertilin β peptide and additionally inhibited sperm binding to the egg plasma membrane (Fig. 2 A). The peptide from cyritestin resulted in 84% inhibition of sperm–egg binding, 93% inhibition of the FI, and 92% inhibition of the FR. The fertilin α peptide showed limited inhibition (∼30%) of sperm–egg binding and fusion. Whether or not this is biologically significant is not yet clear. In comparison, the other two family members, ADAM 4 and 5 peptides, showed essentially no inhibition (Fig. 2 A). The control peptides for all of the five proteins, which contained the same eight amino acids but in a rearranged (scrambled) order, showed only slight or no inhibition (Fig. 2 B).

Bottom Line: This protein family has been named ADAM because all members contain a disintegrin and metalloprotease domain.Full length cDNA clones have been isolated for five ADAMs expressed in mouse testis: fertilin alpha, fertilin beta, cyritestin, ADAM 4, and ADAM 5.Characterization of these two ADAM family members showed that they are both processed during sperm maturation and present on mature sperm.

View Article: PubMed Central - PubMed

Affiliation: Molecular and Cellular Biology, University of California, Davis 95616, USA.

ABSTRACT
Sperm-egg plasma membrane fusion is preceded by sperm adhesion to the egg plasma membrane. Cell-cell adhesion frequently involves multiple adhesion molecules on the adhering cells. One sperm surface protein with a role in sperm-egg plasma membrane adhesion is fertilin, a transmembrane heterodimer (alpha and beta subunits). Fertilin alpha and beta are the first identified members of a new family of membrane proteins that each has the following domains: pro-, metalloprotease, disintegrin, cysteine-rich, EGF-like, transmembrane, and cytoplasmic domain. This protein family has been named ADAM because all members contain a disintegrin and metalloprotease domain. Previous studies indicate that the disintegrin domain of fertilin beta functions in sperm-egg adhesion leading to fusion. Full length cDNA clones have been isolated for five ADAMs expressed in mouse testis: fertilin alpha, fertilin beta, cyritestin, ADAM 4, and ADAM 5. The presence of the disintegrin domain, a known integrin ligand, suggests that like fertilin beta, other testis ADAMs could be involved in sperm adhesion to the egg membrane. We tested peptide mimetics from the predicted binding sites in the disintegrin domains of the five testis-expressed ADAMs in a sperm-egg plasma membrane adhesion and fusion assay. The active site peptide from cyritestin strongly inhibited (80-90%) sperm adhesion and fusion and was a more potent inhibitor than the fertilin beta active site peptide. Antibodies generated against the active site region of either cyritestin or fertilin beta also strongly inhibited (80-90%) both sperm-egg adhesion and fusion. Characterization of these two ADAM family members showed that they are both processed during sperm maturation and present on mature sperm. Indirect immunofluorescence on live, acrosome-reacted sperm using antibodies against either cyritestin or fertilin beta showed staining of the equatorial region, a region of the sperm membrane that participates in the early steps of membrane fusion. Collectively, these data indicate that a second ADAM family member, cyritestin, functions with fertilin beta in sperm-egg plasma membrane adhesion leading to fusion.

Show MeSH
Related in: MedlinePlus