Banerjee Saswati, Dungdung Sandhya Rekha, Das Kaushik, Majumder Gopal Chandra
Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata-700 032, India.
Exp Cell Res. 2006 Jul 15;312(12):2299-308. doi: 10.1016/j.yexcr.2006.03.020. Epub 2006 Apr 24.
Testicular immotile sperm undergo maturation during epididymal transit when these cells pass through caput, corpus, and cauda-epididymal regions. Maturing goat spermatozoa specifically at the distal corpus epididymal stage show head-to-head autoagglutination when incubated in vitro in a modified Ringer's solution. Here, we show the biochemical mechanism of autoagglutination event and its functional significance. A lectin-like molecule located on sperm surface specifically interacts with its receptor of the neighboring homologous cells to cause autoagglutination. Lectin is a Ca++-dependent galactose-specific protein. Failure of the pre- and post-distal corpus sperm to show autoagglutination is due to lack of lectin-like molecule and its receptors, respectively. Maturing sperm at distal corpus stage acquire lectin-like molecule followed by sharp disappearance of its receptor, and this event is synchronously associated with the initiation of sperm forward motility that is essential for fertilization in vivo. Lectin and its receptor isolated from sperm plasma membrane showed high efficacy for blocking autoagglutination phenomenon. The data are consistent with the view that synchronous modulation of homologous cell surface lectin and their receptors constitutes a novel mechanism for cellular regulation by generating waves of signals by manipulating lectin-sugar-dependent "self-talk" and cell-cell "cross-talk".
睾丸中不能活动的精子在通过附睾头部、体部和尾部区域时，会在附睾转运过程中经历成熟。当在改良的林格氏溶液中体外孵育时，处于附睾体远端阶段的成熟山羊精子会出现头对头的自凝集现象。在此，我们展示了自凝集事件的生化机制及其功能意义。位于精子表面的一种凝集素样分子会与其相邻同源细胞的受体特异性相互作用，从而导致自凝集。凝集素是一种依赖钙离子的半乳糖特异性蛋白质。附睾体远端之前和之后的精子未能表现出自凝集，分别是由于缺乏凝集素样分子及其受体。处于附睾体远端阶段的成熟精子会获得凝集素样分子，随后其受体急剧消失，这一事件与精子向前运动的启动同步发生，而精子向前运动对于体内受精至关重要。从精子质膜分离出的凝集素及其受体对阻断自凝集现象显示出高效性。这些数据与以下观点一致，即同源细胞表面凝集素及其受体的同步调节通过操纵凝集素-糖依赖性的“自我对话”和细胞间“相互对话”产生信号波，构成了一种新型的细胞调节机制。
