We all (hopefully) know where babies come from. It all
starts with a single sperm miraculously making contact with an egg cell. The
egg cell accepts the sperm and the two cells fuse their DNA, this is the moment
of conception. Up until very recently the mechanics of this process had been unclear.
How is it that only a singly sperm is able to enter the egg, and furthermore how
did the sperm even attach to the egg? These questions finally have some
concrete answers.
When I took Cellular and Molecular Biology I learned one
very important concept: when in doubt, it’s a protein. This go to tip stands
true for the secret of fertilization; it is all about the proteins. Surface
proteins are one mechanism cells use to communicate with each other. Previous
work had identified a protein on the surface of sperm necessary for egg recognition.
This protein is called Izumo.
Izumo was discovered in 2005. It wasn’t until this year that
the target of this protein was discovered. Juno is to the egg what Izumo is to the sperm.
Why is it that the discovery of Juno took so long? To begin with, the
interaction between Juno and Izumo is short lived. In fact, upon initial
contact of the two proteins, Juno begins to disappear from the egg membrane.
This mechanism is designed to ensure that only one sperm can make it into the
egg. Another reason for the difficulty in finding Juno is that the interactions
between Juno and Izumo are weak, another mechanism designed to limit sperm
access to the egg.
Both proteins are necessary for fertilization to occur.
Knockout mice for either Izumo or Juno were found to be infertile. This research
could lead to potential new forms of birth control. Many women are opposed to
taking the pill because of the hormones they have to ingest. Other
contraceptives like IUDs can be invasive. But imagine a treatment that
disrupted the Juno protein. This protein is (so far) only found in egg cells,
and disruption of its synthesis shouldn’t inhibit normal ovulation and menstruation.
For these reasons I think it would be great to see more options for contraception
being offered.
Posted by Tim Daly
This was a very interesting read! It is exciting to hear that there may be other kinds of birth control besides IUD and the pill. I know many people are too afraid to go through the procedure of the IUD and don't want side effects from birth control pills. Has this new method been tested on people yet?
ReplyDeletePosted by Amber Vien
Since the discovery is so recent there haven't been any drugs designed to target this protein yet. I wouldn't expect to see anything hitting the market for years either, clinical trials and safety procedures can take over a decade!
DeletePosted by Tim Daly
Tim, this is an interesting article. If this Juno disruptor was in fact synthesized, would it be a shot? I don't really see how it could be anything other than a pill...and that would be still be putting a hormone/something artificial inside of your body. Do you think that it would still have a broad appeal if this were the case?
ReplyDelete-Posted by Taylor Schille
I think the appeal of this theoretical treatment would mainly be that it would be non hormonal, not that it wouldn't be artificial. Many women have negative side effects to the hormones that the pill contains (although many women also see positive side effects, so it really remains a personal decision).
DeletePosted by Tim Daly
Great post, Tim! I have a few questions regarding the mice test. How would the researchers knock out either mice Juno or Izumo? And during that process, could it be a damage to other parts of the gamete, which causes infertile? Another question for new possible birth control method, could the interruption cause permanent damage to Izumo or Juno gene expression?
ReplyDeletePost by Yim Hui
I think the scientists were able to solely remove the protein and avoid other damage to the cells by targeting the gene which codes for the protein. There are several techniques to achieve this given modern technology, I am not sure which method was used though. Targeted gene knockout is not a rare or unusual procedure though. As for your last question, I think it really depends on what the treatment is and who the treatment is for. Females are born with all of their eggs, whereas males produce sperm on a regular basis. I could imagine that it would be less likely to permanently damage sperm as they regenerate constantly.
DeletePosted by Tim Daly
This was a very interesting concept to read about! If both knock out mice for Juno and Izumo were found to be infertile then instead of making a birth control for women that affects the Juno protein, couldn't they do so for men to interact with the Izumo protein? Finally men would have to worry about taking birth control instead! Woohoo!
ReplyDeletePosted by Kristen Whitehead
I completely agree with your comment! i think it would be great to make men more aware of their role in pregnancy. Our society views pregnancy and birth control as a female issue, when in reality it takes two to get pregnant. men should be just as responsible as women!
DeletePosted by Tim Daly
There are so many new options for women when it comes to birth control. I had no idea these two proteins could potentially be a new form of birth control. Do you know of any more research that has been done in this field?
ReplyDeletePosted by: Lindsey Janof
Do you know if the Juno protein is used anywhere else in the body, or is it just related to an egg cell? I wonder if knocking out Juno would cause any negative symptoms in other parts of the body.
ReplyDelete-Samuel Ustayev
I would imagine that the Juno protein is specific to egg cells because of its interaction with the sperm counter part.
Deleteposted by Tim Daly
As someone who has taken Cellular and Molecular Biology I definitely share your sentiment Tim. My question is do you personally think knocking out Juno proteins would be more effective then just knocking out the Izumo proteins?
ReplyDeletePosted by Jacob Geier
No
Deleteposted by Tim Daly