Regionalized lipid diffusion in the plasma membrane of mammalian spermatozoa
Regionalized lipid diffusion in the plasma membrane of mammalian spermatozoa
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DOI：
10.1095/biolreprod59.6.1506
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发表时间：
1998-12-01
影响因子：
3.6
通讯作者：
Jones, R
中科院分区：
文献类型：
--
作者：
Wolfe, CA;James, PS;Jones, R
哺乳动物精子的质膜表现出明显的横向不对称性，许多糖蛋白被限制在特定的结构域。其中一些抗原在膜上自由扩散，而另一些抗原在位置上是静止的。目前尚不清楚这些概念是否也适用于膜脂。在这项研究中，我们使用光漂白后荧光恢复（FRAP）技术对5种哺乳动物精子（公牛、野猪、公羊、小鼠和豚鼠）不同表面区域的脂质动力学进行了空间解析。精子质膜上负载5-（n -十八烷基）氨基荧光素（ODAF）报告探针，通过FRAP分析测定其在各区域的扩散。结果表明，在公牛、公猪、公羊和小鼠的活精子中，扩散系数(D)在顶体和顶体后显著高于尾部中部和主段。另一方面，在死亡或渗透细胞中，形成了大的不动相，特别是在精子尾部，这严重降低了D值，ODAF扩散也对温度和膜内蛋白质组分与多聚甲醛交联敏感。豚鼠的精子几乎在所有方面都不同于其他被测试物种的精子。由此可见，活精子质膜中的脂质扩散在不同表面结构域之间存在显著差异，这可能是由于组成的异质性，或者是双层结构域的不同，或者是由于膜内屏障的存在阻碍了结构域之间的自由交换。本研究强调了膜脂在精子成熟和获能等发育过程中调控精子表面抗原极化迁移的重要作用。
The plasma membrane of mammalian spermatozoa shows pronounced lateral asymmetry with many glycoproteins restricted to specific domains. Some of these antigens are freely diffusing throughout the membrane whereas others appear static in position. It is not clear whether these concepts also apply to membrane lipids. In this investigation we have used fluorescence recovery after photobleaching (FRAP) techniques to spatially resolve lipid dynamics in various surface domains of 5 species of mammalian spermatozoa (bull, boar, ram, mouse, and guinea pig). Sperm plasma membranes were loaded with 5-(N-octadecanoyl)aminofluorescein (ODAF) reporter probe, and its diffusion was measured in various domains by FRAP analysis. Results showed that in live bull, boar, ram, and mouse spermatozoa, diffusion coefficients (D) were significantly higher over the acrosome and postacrosome than on the midpiece and principal piece of the tail. In dead or permeabilized cells, on the other hand, large immobile phases developed, particularly on the sperm tail, that severely reduced D values, ODAF diffusion was also sensitive to temperature and cross-linking of protein components within the membrane with paraformaldehyde. Guinea pig spermatozoa were different in almost all respects from those of the other species tested. It is concluded that lipid diffusion in the plasma membrane of live spermatozoa varies significantly between surface domains, because of either compositional heterogeneity, or differences in bilayer disposition, or the presence of intramembranous barriers that impede free exchange between domains. This study emphasizes the important role of membrane lipids in regulating polarized migration of sperm surface antigens during developmental processes such as maturation and capacitation.