PNAS: New sperm membrane protein helps mammalian fertilization.

May 8, 2020 / / - Fertilization is a basic process of sexual reproduction, in which male and female maters mix genetic material to produce a new and unique individual.
now, researchers from Japan have discovered a new factor that may help coordinate this extremely complex life event.
in a recent study, researchers at Osaka University and Baylor Medical School found a new protein involved in the fusion of fertilized egg membranes during fertilization and named it fertilized membrane protein (Fertilization Directing Membrane Protein, FIMP).
the human body is made up of trillions of cells that come from a fertilized egg.
egg fusion is a key event in mammalian fertilization, and three proteins are known to promote this process.
team discovered the sperm membrane protein IZUMO1 in 2005 and named it after a shrine that celebrates marriage.
with the "JUNO" egg membrane protein, discovered nine years later, named after the Roman goddess of fertility.
together to form protein complexes that work with ovarian cell tetamine protein CD9.
because the three proteins can't explain the complex molecular interactions, people are looking for other factors.
Photo Source: Dr Yoshitaka Fujihara, Associate Professor, Institute of Microbiological Diseases, PNAS, and lead author of the study, explained: "Using CRISPR/Cas9-mediated genomic editing techniques, we focused on testicular-specific 4930451I11Rik genes to produce mutations with selective inactivation or 'off' genes to 'knock out' mice.
although IZUMO1 is found in sperm knocked out by the 4930451I11Rik gene, they cannot fuse with oocytes, and KO male mice have been shown to have serious fertility problems.
"4930451I11Rik gene encodes two protein variants, one trans-membrane (TM) subtype and the other secretion-type subtype.
and GM recovery tests with CRISPR/cas9 mediated show that only TM subsypes are necessary for fine egg fusion.
researchers named the TM subtype as a membrane protein that affects fertilization and clarified that it is essential for fertilization and that its role in membrane fusion is different from that of IZUMO1.
the fluorescent mCherry marker locates FIMP to the equatorial segment of the sperm, where fine egg fusion occurs.
Masahito Ikawa, one of the authors of the IZUMO1 study, speculated on the significance and future trends of their study.
"Our findings support the potential role of human FIMP in sperm function.
further study of the causes of FIMP's knock-out of male infertility in mice and the interaction of type I transmeral proteins located on sperm heads.
this knowledge could be used to develop new treatments for in vitro infertility, as well as non-hormonal male-specific contraceptives.
" () Reference: Novel sperm protein protein solutions to the system of fertilization Yoshitaka Fujihara et al. Spermatozoa lacking Fertilization ResourcesIng Protein (FIMP) fail to fuse with oocytes in mice, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.1917060117.