【原创论文】小鼠杀菌渗透增强性蛋白起源于睾丸及附睾表达并定位于精子中

杀菌渗透增强性蛋白（BPI）是具有抗革兰氏阴性菌活性的内源性杀菌蛋白。在本研究中，我们通过自行制备的多克隆抗体，检测了BPI蛋白在小鼠出生后睾丸及附睾组织中的表达，以及在附睾精子头部的亚细胞定位。实验结果表明，睾丸和附睾均独立表达BPI基因。在附睾中，自起始段至尾部，BPI蛋白的表达水平递减，并逐步特异性富集于亮细胞的胞质中。在顶体反应前的顶体基质内可见BPI蛋白，应起源于睾丸表达；顶体反应后，可见BPI蛋白分布于整个精子头部质膜表面，尤其是赤道板区域，可能有睾丸或附睾表达的两种起源。我们的研究结果提示，BPI蛋白可能参与顶体反应前后精子质膜结构的调控，并参与后续的精卵融合过程。

Bactericidal/permeability-increasing protein originates in both the testis and the epididymis and localizes in mouse spermatozoa

Bactericidal/permeability-increasing protein （BPI） is an endogenous antibiotic protein with activity against gram-negative bacteria. In the present study, we examined the expression of BPI in postnatal mouse testes and epididymides as well as the subcellular localization within epididymal spermatozoa. Our results showed that, BPI mRNA was expressed in testis and epididymis independently. Throughout the epididymis, the BPI protein level gradually decreased in the epididymal epithelium in a spatial manner, specialized within the cytoplasm of clear cells in the cauda part. We detected BPI proteins in intact acrosome, implying its testicular origin; on the other hand, after the acrosome reaction, BPI proteins were observed dispersed across the entire sperm head, especially enriched at the equatorial segment. Our findings suggested a dual origin of the BPI that generated both in the testis and epididymis, and associated with mouse spermatozoa. BPI protein might be involved in the dynamics modification of the sperm plasma membrane and also the fertilization process.