Roles of Sulfogalactosylglycerolipid (SGG) and Its Binding Proteins in Fertilization.
Notice bibliographique
Résumé
SGG is an evolutionarily conserved sulfoglycolipid present at 10 mole% of total lipids on the surface of mammalian male germ cells. On mature sperm, SGG is localized exclusively on the sperm anterior head plasma membrane (APM), the site where sperm interact with zona pellucida (ZP). We have shown that SGG not only has direct ZP affinity, but also plays an important role in the formation of capacitated sperm lipid rafts, which possess ZP binding ability. Also, SGG and its analog, Sulfogalactosylceramide (SGC), possess affinity for a number of molecules, including heat shock protein 70 (Hsp70) and a ZP-binding protein, arylsulfatase A (ASA), both existing in lipid rafts. Since SGG is present abundantly in sperm APM, we hypothesize that it may recruit other sperm surface proteins important for fertilization to the APM region during capacitation. Synergistic action between SGG and these APM proteins, which may also have SGG affinity, would stabilize the binding of sperm to the ZP. Nitrogen cavitation at 650 psi selectively disrupts the APM. APM vesicles containing lipids and membranous proteins can be pelletted upon ultracentrifugation, whereas peripheral plasma membrane proteins of the APM would remain in the supernatant (SN). Notably, the levels of APM vesicles from capacitated sperm were higher than those from non-capacitated gametes, confirming the significance of APM vesicles in ZP binding. Our proteomic analysis further revealed a number of ZP binding proteins in these vesicles, including SED1, zonadhesin, angiotensin converting enzyme, Sp32, and glutathione S-transferase mu 2 (GST). Some of these proteins may have direct SGG affinity. In fact, our initial attempt to characterize SGG binding proteins using the "SN" fraction indicated that SP-10, Sp32, and GST, all with a similar molecular mass range (25-28 kDa), formed complexes with SGG liposomes, which could then be floated up in a sucrose gradient by ultracentrifugation. Similar experimental approaches are being carried out to identify SGG binding proteins in APM vesicles, with the expectation that some of them would have ZP affinity. Interestingly, chaperone proteins, Hsp70 and Hsp86, were also present in higher amounts in APM vesicles of capacitated sperm. Hsp70 is known to oligomerize upon its binding to SGC. We therefore propose that SGG may induce oligomerization of Hsp70 and perhaps also Hsp86 in the APM entity, especially in capacitated sperm. This would promote the clustering of ZP binding proteins and subsequently their synergistic action in ZP binding. Experiments are underway to validate this hypothesis. Our study should reveal whether SGG can recruit ZP binding proteins to the APM entity via its direct affinity to these proteins and/or indirect influence through their interaction with the chaperone proteins, Hsp70 and Hsp86. Funded by CIHR, NSERC, and DPST (The Development and Promotion of Science and Technology Talented Project Thailand scholarship). (poster)
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».