Arama Eli, Agapite Julie, Steller Hermann
Howard Hughes Medical Institute, Strang Laboratory of Cancer Research, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Dev Cell. 2003 May;4(5):687-97. doi: 10.1016/s1534-5807(03)00120-5.
The final stage of spermatid terminal differentiation involves the removal of their bulk cytoplasm in a process known as spermatid individualization. Here we show that apoptotic proteins play an essential role during spermatid individualization in Drosophila melanogaster. Several aspects of sperm terminal differentiation, including the activation of caspases, are reminiscent of apoptosis. Notably, caspase inhibitors prevent the removal of bulk cytoplasm in spermatids and block sperm maturation in vivo, causing male sterility. We further identified loss-of-function mutations in one of the two Drosophila cyt-c genes, cyt-c-d, which block caspase activation and subsequent spermatid terminal differentiation. Finally, a giant ubiquitin-conjugating enzyme, dBruce, is required to protect the sperm nucleus against hypercondensation and degeneration. These observations suggest that an apoptosis-like mechanism is required for spermatid differentiation in Drosophila.
精子细胞终末分化的最后阶段涉及在一个被称为精子细胞个体化的过程中去除其大部分细胞质。在这里我们表明，凋亡蛋白在黑腹果蝇的精子细胞个体化过程中发挥着至关重要的作用。精子终末分化的几个方面，包括半胱天冬酶的激活，都让人联想到细胞凋亡。值得注意的是，半胱天冬酶抑制剂可阻止精子细胞中大部分细胞质的去除，并在体内阻断精子成熟，导致雄性不育。我们进一步鉴定出果蝇两个细胞色素c基因之一cyt-c-d中的功能丧失突变，该突变会阻断半胱天冬酶激活及随后的精子细胞终末分化。最后，一种巨大的泛素结合酶dBruce是保护精子细胞核免受过度凝聚和退化所必需的。这些观察结果表明，果蝇的精子细胞分化需要一种类似细胞凋亡的机制。
