Glycopolymer induction of mouse sperm acrosomal exocytosis shows highly cooperative self-antagonism

Rodolis, Maria T.; Huang, He; Sampson, Nicole S.

doi:10.1016/j.bbrc.2016.05.003

Cited by 5 publications

(40 citation statements)

References 36 publications

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“…AE induction was measured at 5, 10, and 20 μM polymers using a triple-stain flow cytometry assay. 1 Figure 2 illustrates the AE induction efficacy of polycyclooctene and polynorbornene displaying fucose, GlcNAc, or mannose normalized to the positive control of AE induction by calcium ionophore A23187. Polymers displaying glucose were used as a negative control.…”

Section: Resultsmentioning

confidence: 99%

“… AE induction by norbornene [poly( 1 ) 100 ] 1 and cyclooctene [poly( 2 ) 100 ] backbone polymers. Normalized AE% = (AE% induction by polymers – AE% induction by negative control)/(AE% induction by positive control – AE% induction by negative control).…”

Section: Resultsmentioning

confidence: 99%

“…At higher concentrations of poly( 1a ) 100 , highly cooperative inhibition occurred and the level of AE induction dropped to ∼27%. 1 , 17 This type of cooperative inhibition is diagnostic of a multivalent activation process that competes poorly with a second monovalent binding event at high probe concentrations. 27 − 30 Steric occlusion of the cell surface as more receptors are occupied may also prevent di- or multivalent engagement.…”

Section: Resultsmentioning

confidence: 99%

“…Cooperative inhibition was absent for the mannose polymer and incomplete for the GlcNAc polymer within the testable concentration range. 1 , 17 …”

Section: Resultsmentioning

confidence: 99%

“…Mouse sperm isolation and flow cytometry experiments were conducted following previously published methods. 1 The acrosome integrity of live sperm was normalized to PBS (negative control) and 5 μM A23187 (positive control). Normalized AE% was calculated using [(AE% of glycopolymer – AE% of negative control)/(AE% of positive control – AE% negative control)].…”

Section: Methodsmentioning

confidence: 99%

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Sugars Require Rigid Multivalent Displays for Activation of Mouse Sperm Acrosomal Exocytosis

et al. 2017

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As a prerequisite to mammalian fertilization, the sperm acrosomal vesicle fuses with the plasma membrane and the acrosome contents are exocytosed. Induction occurs through engagement of the sperm receptors by multiple sugar residues. Multivalent polymers displaying mannose, fucose, or GlcNAc are effective synthetic inducers of mouse sperm acrosomal exocytosis (AE). Each carbohydrate is proposed to have a distinct binding site on the sperm cell surface. To determine the role of the scaffold structure in the efficiency of AE induction, different polymer backbones were employed to display the different activating sugar residues. These glycopolymers were prepared by ruthenium-catalyzed ring-opening metathesis of 5-substituted norbornene or cyclooctene. The conformations of the glycopolymers were characterized by small-angle X-ray scattering. Polynorbornene displaying mannose, fucose, or GlcNAc forms flexible cylinders in aqueous solution. However, polycyclooctenes displaying any of these same sugars are much more flexible and form random coils. The flexible polycyclooctenes displaying fucose or GlcNAc were less effective inducers of AE than their norbornene counterparts. In contrast, polycyclooctene displaying mannose was the most effective AE inducer and had a more collapsed spherelike structure. Our results suggest that the AE efficacy of fucose, GlcNAc, and mannose polymers relies on a relatively rigid polymer that can stabilize receptor signaling complexes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Cooperative inhibition was absent for the mannose polymer and incomplete for the GlcNAc polymer within the testable concentration range. 1 , 17 …”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Sugars Require Rigid Multivalent Displays for Activation of Mouse Sperm Acrosomal Exocytosis

et al. 2017

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Seeing is believing: Current methods to observe sperm acrosomal exocytosis in real time

Balestrini

Jabloñski

Schiavi‐Ehrenhaus

et al. 2020

Molecular Reproduction Devel

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Acrosomal exocytosis (AR) is a critical process that sperm need to undergo to fertilize an egg. The evaluation of the presence or absence of the acrosome is usually performed by using lectins or dyes in fixed cells. With this approach, it is neither possible to monitor the dynamic process of exocytosis and related molecular events while discriminating between live and dead cells, nor to evaluate the acrosomal status while sperm reside in the female reproductive tract. However, over the last two decades, several new methodologies have been used to assess the occurrence of AR in living cells allowing different groups to obtain information that was not possible in the past. These techniques have revolutionized the whole study of this process. This review summarizes current methods available to analyze AR in living cells as well as the important information that emerged from studies using these approaches.

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Triblock Glycopolymers with Two 10-mer Blocks of Activating Sugars Enhance the Activation of Acrosomal Exocytosis in Mouse Sperm

Mendez,

Kennedy,

Bhatia

et al. 2024

ACS Bio Med Chem Au

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Carbohydrate recognition is imperative for the induction of sperm acrosomal exocytosis (AE), an essential phenomenon in mammalian fertilization. In mouse sperm, polynorbornene 100-mers displaying fucose or mannose moieties were effective at inducing AE. In contrast, glycopolymers exhibiting glucose sugars resulted in no AE activation. To further elucidate the role of ligand density on the activation of AE in mouse sperm, a triple-stain flow cytometry assay was employed to determine the efficacy of polynorbornene block copolymers with barbell-like sequences as initiators of AE. Triblock (ABA or ABC) copolymers were synthesized by ring-opening metathesis polymerization (ROMP) with one or two activating sugars, mannose or fucose, and one nonactivating sugar, glucose. The active ligand fractions in the polymers varied from 10, 20, or 40%. Simultaneously, random copolymers comprising 20% activating ligands were prepared to confirm the importance of ligand positionality in AE activation in mouse sperm. Polynorbornene 100-mers possessing two 10-mer blocks of activating sugars were the most effective copolymers at inducing AE with levels of AE comparable to their homopolymer counterparts and more effective than their random analogues. Small-angle X-ray scattering (SAXS) was then performed to verify that there were no differences in the conformations of the glycopolymers contributing to their varying AE activity. SAXS data analysis confirmed that all of the glycopolymers assumed semiflexible cylindrical structures with similar radii and Kuhn lengths. These findings suggest that the overall ligand density of the sugar moieties in the polymer is less important than the positionality of short blocks of high-density ligands for AE activation in mouse sperm.

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Glycopolymer induction of mouse sperm acrosomal exocytosis shows highly cooperative self-antagonism

Cited by 5 publications

References 36 publications

Sugars Require Rigid Multivalent Displays for Activation of Mouse Sperm Acrosomal Exocytosis

Sugars Require Rigid Multivalent Displays for Activation of Mouse Sperm Acrosomal Exocytosis

Seeing is believing: Current methods to observe sperm acrosomal exocytosis in real time

Triblock Glycopolymers with Two 10-mer Blocks of Activating Sugars Enhance the Activation of Acrosomal Exocytosis in Mouse Sperm

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