Sperm MMP-2 is indispensable for fast electrical block to polyspermy at fertilization in Xenopus tropicalis.

Mami Watabe, Azusa Hiraiwa, Mami Sakai, Tomoyo Ueno, Shuichi Ueno, Keisuke Nakajima, Yoshio Yaoita, Yasuhiro Iwao

Molecular reproduction and development 2021 Nov

filter terms:

Sperm matrix metalloproteinase-2 (MMP-2) is necessary for frog fertilization. Monospermy is ensured by a fast, electrical block to polyspermy mediated by a positive fertilization potential. To determine the role of the MMP-2 hemopexin domain (HPX) in a fast block to polyspermy during fertilization of the frog, Xenopus tropicalis, we prepared mutant frogs deficient in mmp2 gene using the transcription activator-like effector nuclease method. mmp2 ΔHPX (-/-) sperm without MMP-2 protein were able to fertilize wild-type (WT; +/+) eggs. However, polyspermy occurred in some eggs. The mutant sperm generated a normal fertilization potential amounting to 10 mV, and were able to fertilize eggs at 10 mV, at which WT sperm never fertilized. Sensitivity during voltage-dependent fertilization decreased in mutant sperm. This study demonstrates for the first time that the genetic alteration of the MMP-2 molecule in sperm causes polyspermy during fertilization of a monospermic species. Our findings provide reliable evidence that sperm MMP-2 is indispensable for the fast, electrical block to polyspermy during Xenopus fertilization. © 2021 Wiley Periodicals LLC.

Citation

Mami Watabe, Azusa Hiraiwa, Mami Sakai, Tomoyo Ueno, Shuichi Ueno, Keisuke Nakajima, Yoshio Yaoita, Yasuhiro Iwao. Sperm MMP-2 is indispensable for fast electrical block to polyspermy at fertilization in Xenopus tropicalis. Molecular reproduction and development. 2021 Nov;88(11):744-757