Khatchadourian Karine, Smith Charles E, Metzler Martina, Gregory Mary, Hayden Michael R, Cyr Daniel G, Hermo Louis
Department of Anatomy and Cell Biology, McGill University, Montreal, Canada.
Mol Reprod Dev. 2007 Mar;74(3):341-59. doi: 10.1002/mrd.20564.
Huntingtin interacting protein 1 (HIP1) is an endocytic adaptor protein with clathrin assembly activity that binds to cytoplasmic proteins, such as F-actin, tubulin, and huntingtin (htt). To gain insight into diverse functions of HIP1, we characterized the male reproductive defect of HIP1(-/-) mice from 7 to 30 weeks of age. High levels of HIP1 protein were expressed in the testis of wild-type mice as seen by Western blots and as a reaction over Sertoli cells and elongating spermatids as visualized by immunocytochemistry. Accordingly, major structural abnormalities were evident in HIP1(-/-) mice with vacuolation of seminiferous tubules caused by an apparent loss of postmeiotic spermatids and a significant reduction in mean profile area. Remaining spermatids revealed deformations of their heads, flagella, and/or acrosomes. In some Sertoli cells, ectoplasmic specializations (ES) were absent or altered in appearance accounting for the presence of spherical germ cells in the epididymal lumen. Quantitative analyses of sperm counts from the cauda epididymidis demonstrated a significant decrease in HIP1(-/-) mice compared to wild-type littermates. In addition, computer-assisted sperm analyses indicated that velocities, amplitude of lateral head displacements (ALH), and numbers and percentages of sperm in the motile, rapid, and progressive categories were all significantly reduced in HIP1(-/-) mice, while the numbers and percentages of sperm in the static category were greatly increased. Taken together, these various abnormalities corroborate reduced fertility levels in HIP1(-/-) mice and suggest a role for HIP1 in stabilizing actin and microtubules, which are important cytoskeletal elements enabling normal spermatid and Sertoli cell morphology and function.
亨廷顿相互作用蛋白1（HIP1）是一种具有网格蛋白组装活性的内吞衔接蛋白，可与细胞质蛋白结合，如F-肌动蛋白、微管蛋白和亨廷顿蛋白（htt）。为深入了解HIP1的多种功能，我们对7至30周龄的HIP1基因敲除小鼠的雄性生殖缺陷进行了表征。通过蛋白质免疫印迹法可见，野生型小鼠睾丸中表达高水平的HIP1蛋白，免疫细胞化学显示该蛋白在支持细胞和伸长的精子细胞中呈阳性反应。相应地，HIP1基因敲除小鼠出现明显的结构异常，生精小管出现空泡化，这是由于减数分裂后精子细胞明显缺失以及平均轮廓面积显著减小所致。剩余的精子细胞头部、鞭毛和/或顶体出现变形。在一些支持细胞中，胞质特化结构（ES）缺失或外观改变，这解释了附睾管腔中存在球形生殖细胞的原因。对附睾尾精子计数的定量分析表明，与野生型同窝小鼠相比，HIP1基因敲除小鼠的精子数量显著减少。此外，计算机辅助精子分析表明，HIP1基因敲除小鼠的精子运动速度、头部横向位移幅度（ALH）以及活动、快速和前进类别的精子数量和百分比均显著降低，而静止类别的精子数量和百分比则大幅增加。综上所述，这些各种异常情况证实了HIP1基因敲除小鼠的生育能力降低，并表明HIP1在稳定肌动蛋白和微管方面发挥作用，而肌动蛋白和微管是重要的细胞骨架成分，对正常精子细胞和支持细胞的形态及功能至关重要。
