RESUMEN
The sterility of hormone-sensitive lipase (HSL) knockout mice clearly shows the link between lipid metabolism and spermatogenesis. However, which substrate or product of this multifunctional lipase affects spermatogenesis is unclear. We found that an HSL protein with a His-tag at the N-terminus preserved the normal hydrolase activity of cholesteryl ester (CE) but the triglyceride lipase (TG) activity significantly decreased in vitro. Therefore, mice with this functionally incomplete HSL (His-HSL) were produced on a background of HSL deficiency (HSL-/- h). As a result, HSL-/- h testis has an 8.65-fold higher CE activity than wild-type testis but a twofold higher TG activity than wild-type testis. To compare His-HSL and wild-type HSL in vitro and in vivo, we confirmed that the His-tag significantly suppressed HSL TG activity. From our results, we believe that TG activity was affected by the His-tag insertion, but CE activity was not influenced. Furthermore, the His-tag protected HSL from binding to the inhibitor BAY. From our study, TG activity and BAY binding sites were affected by N-terminal His-tag insertion.
Asunto(s)
Histidina , Lipasa , Esterol Esterasa , Testículo/enzimología , Animales , Ésteres del Colesterol/genética , Ésteres del Colesterol/metabolismo , Histidina/biosíntesis , Histidina/genética , Humanos , Lipasa/biosíntesis , Lipasa/genética , Masculino , Ratones , Ratones Noqueados , Esterol Esterasa/biosíntesis , Esterol Esterasa/genéticaRESUMEN
OBJECTIVE: To study the effects of nonylphenol and cadmium on acrosome reaction in vitro in mouse spermatozoa. METHODS: Sperm were collected from the vas deferens of mice, capacitated in vitro and stimulated with A23187 at 30 micromol/L to induce acrosome reaction. Then the sperm suspension was treated with nonylphenol at 10, 20, 30, 60 and 100 micromol/L or cadmium at 500, 2500 and 5 000 micromol/L, and the control group treated with the carrier solvent. Acrosome reaction of the sperm was analyzed by FITC-PSA staining. RESULTS: Compared with the control group, nonylphenol significantly inhibited acrosome reaction at the concentration of > 60 micromol/L (P < 0.01), but not at < 30 micromol/L (P > 0.05), and the sperm survival rate was reduced with increased concentration of nonylphenol. However, cadmium exhibited no significant influence on either acrosome reaction (P > 0.05) or sperm survival rate at 500 - 5 000 micromol/L. CONCLUSION: Nonylphenol and cadmium affect the spermatogenesis of mice in different ways; the former directly inhibits sperm acrosome reaction, while the latter has no direct effect on it.