For years, midbodies were dismissed as mere cellular waste from cell division. But research is shifting this perspective! Recent studies reveal that midbodies and their remnants (MBRs) are dynamic assembly sites for RNA and active translation.

These tiny structures are now recognized as vital players in cellular communication, carrying specific mRNAs that influence cell fate, growth, and even cancer progression.

This transformation in understanding underscores the importance of re-evaluating what we once considered “junk” in the cell.

Midbodies are not leftovers but sophisticated hubs of genetic information and protein synthesis, opening new avenues in cell biology and disease research.

 

Midbody Remnant Podcast - Published Paper

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by Google NotebookLM | "The midbody and midbody remnant are assembly sites for RNA and active translation" Sung-Sik Park,+11 more - 20 Nov 2022 - bioRxiv

 Transcript of podcast

Speaker 1 00:00 – 00:07

All right, listeners, buckle up. Today, we’re going deep into the world of cell biology, specifically mid-bodies.

Speaker 2 00:07 – 00:08

Mid-bodies.

Speaker 1 00:08 – 00:10

Maybe not a word you hear every day, right?

Speaker 2 00:10 – 00:10

Right.

Speaker 1 00:10 – 00:24

There are these tiny structures that pop up when cells decide to split, you know, do the whole division thing. And for the longest time scientists kind of thought they were just cellular junk, like leftover bits from a demolition project, scraps.

Speaker 2 00:24 – 00:36

Yeah, it’s true. They were viewed as the cellular equivalent of just construction debris. But, big but, it turns out these little structures are way more interesting than anybody ever expected.

Speaker 1 00:36 – 00:41

Ooh, a plot twist already. So what happened? Someone find a diamond in that cellular rubble?

Speaker 2 00:41 – 00:50

Not a diamond, but something just as valuable. Information. See, we now know that mid-bodies, they aren’t just degraded inside the cell.

Speaker 1 00:50 – 00:50

They’re not.

Speaker 2 00:50 – 00:56

Nope. They get packaged up and sent out like a little delivery service as extracellular vesicles.

Speaker 1 00:56 – 01:02

Extracellular vesicles, tiny little packages sent out from dividing cells. Okay, why should I care about this?

Speaker 2 01:02 – 01:06

These packages, they’re not just hauling away trash, they’re carrying messages.

Speaker 1 01:06 – 01:07

Messages.

Speaker 2 01:07 – 01:14

Yeah, messages that can actually talk to other cells, affect how tissues develop even, even play a role in tumor growth.

Speaker 1 01:14 – 01:17

Wait, hold up. Did you say tumor growth? Like cancer?

Speaker 2 01:17 – 01:28

It’s a possibility. And that’s what makes this research so groundbreaking. We have to completely rethink what we know about these mid-bodies. About cell division. About health and disease.

Speaker 1 01:28 – 01:35

Okay, you’ve got my attention. But if these little packages are delivering messages, what’s in them? What are they saying?

Speaker 2 01:35 – 01:42

Here’s the really wild part, the research you sent. It found that at the heart of the midbody is an RNA granule.

Speaker 1 01:42 – 01:47

RNA, like the messenger molecule, the 1 that carries instructions from DNA to build proteins.

Speaker 2 01:47 – 01:59

Exactly. And the fact that RNA is such a big deal in these mid-bodies, it means they’re not just random leftovers. They’re organized, they have a purpose. Like imagine finding a blueprint in a pile of rubble. Suddenly the story’s way more interesting.

Speaker 1 01:59 – 02:06

You weren’t kidding when you said fascinating. But how did scientists figure this out? It sounds like some serious cellular detective work.

Speaker 2 02:06 – 02:11

Oh it was. They did this clever experiment with CHO cells.

Speaker 1 02:11 – 02:12

CHO cells.

Speaker 2 02:12 – 02:24

Chinese hamster ovary cells. They’re often used in research. Yeah. They looked at the RNA at different points in the cell’s life, when it’s just hanging out, when it’s dividing, and specifically at the midbody stage. And what they found?

Speaker 1 02:24 – 02:25

What’d they find? 22,

Speaker 2 02:25 – 02:35

count them, 22 specific messenger RNA molecules, mRNAs, that were way more common in the mid-bodies than at any other stage.

 

Speaker 1 02:35 – 02:41

So not just any old RNA, a specific set hanging out in the mid-body. Okay, what were they? What made them special?

 

Speaker 2 02:41 – 02:47

Well, many of them had to do with cell fate, growth even. Genes that are linked to cancer. Oncogenes.

 

Speaker 1 02:48 – 02:50

Oncogenes. In the mid-body. That sounds a little ominous.

 

Speaker 2 02:50 – 02:57

Yeah, definitely raised some eyebrows in the lab. The idea that these mid-bodies could be involved in cancer, it’s, well, it’s a bit alarming.

 

Speaker 1 02:57 – 03:03

So maybe we need to start thinking about these mid-bodies not just as debris but as like targets for cancer therapies.

 

Speaker 2 03:03 – 03:09

Potentially. But we’re really just scratching the surface here. There’s so much more to learn about what these mid-bodies can do.

 

Speaker 1 03:09 – 03:13

I’m all in. What other mRNAs did they find? Any more surprises?

 

Speaker 2 03:13 – 03:24

Oh, absolutely. Several. 1 was KLF4. This gene, it’s involved in pluripotency. You know, that’s the thing that lets a stem cell become practically any other cell type in the body.

 

Speaker 1 03:24 – 03:30

So KLF4 is in stem cells and now it’s showing up in mid-bodies. That’s got to be connected somehow.

 

Speaker 2 03:30 – 03:45

Right. That’s what’s so cool about this research. It’s like finding puzzle pieces from totally different areas of biology and realizing they fit together. KLF4 in the midbody. Maybe these structures are linked to stem cell behavior too. And that has huge implications for like regenerative medicine.

 

Speaker 1 03:45 – 03:49

Okay. My mind is already blown. But we’re not done with the mRNA surprises, are we?

 

Speaker 2 03:49 – 04:03

Nope. Not even close. There’s 1 more you’ll find interesting. It’s the mRNA for a protein called Kif23mklp1. And get this, mklp1 is actually involved in building the midbody itself.

 

Speaker 1 04:03 – 04:08

Hold on, so the midbody contains the instructions for building itself? That’s like a building containing its own blueprint.

 

Speaker 2 04:08 – 04:12

It really is. And that just shows us how much we still don’t know about these structures. It really challenges all our assumptions.

 

Speaker 1 04:13 – 04:22

We started with cellular garbage And now we’re talking cancer, stem cells, and self-assembly. This is amazing. So where do we go from here?

 

Speaker 2 04:22 – 04:46

Well, the paper you sent, it didn’t just call the midbody a container for these mRNAs. They called it an assembly site for RNA and active translation. And that active translation part, that’s where things get really interesting. Active translation, it means the midbody isn’t just storing these mRNAs, it’s actually using them to build proteins right there on site. And proteins, those are the workhorses of the cell. They do pretty much everything.

 

Speaker 1 04:46 – 04:50

So it’s not just a library, it’s a whole construction site. Wow. But when does all this building happen?

 

Speaker 2 04:50 – 04:59

That’s the really cool part. The research says this translation process, it starts right as those dividing cells go back into the G1 phase of the cell cycle.

 

Speaker 1 04:59 – 05:01

G1 phase. Okay, remind me about that again.

 

Speaker 2 05:01 – 05:10

So imagine the cells just finished this huge project mitosis dividing in 2. Now it’s entering the G1 phase, like time to chill, recover, get back to its normal routine.

 

Speaker 1 05:10 – 05:23

Right. The after party. So the cells are going back to their normal lives and these mid-body construction sites kick into gear. But didn’t you say these mid-bodies get released from the cell so they’re still building proteins even after they’re floating around outside?

 

Speaker 2 05:23 – 05:36

Exactly and that’s a huge deal. Active translation happening outside a cell in an extracellular vesicle never been seen before. Opens up a whole can of worms about what these MBRs are doing out there.

 

Speaker 1 05:36 – 05:43

It’s like they’re little mobile factories cruising around building stuff, maybe even messing with other cells. What does that mean for, well, for anything?

 

Speaker 2 05:43 – 05:56

It could be a whole new way cells communicate, right? Imagine these MBRs, or MBSomes as some folks call them, acting like couriers, delivering messages, not just as RNA, but as actual functional proteins.

 

Speaker 1 05:56 – 06:03

We started with cellular garbage and now we’re talking about cancer, stem cells, secret messages, and all thanks to these tiny mid-bodies this is incredible.

 

Speaker 2 06:03 – 06:09

And there’s more. Remember that mRNA for KIF-23 MKLP1, the 1 that builds the mid-body.

 

Speaker 1 06:09 – 06:11

Yeah, the self-assembling blueprint.

 

Speaker 2

06:11 – 06:15

Well turns out MKLP1, it might be even more talented than we thought.

 

Speaker 1 06:15 – 06:17

Oh, what else can it do?

 

Speaker 2 06:17 – 06:28

Not only does it help build the midbody, it also seems to be organizing the RNA inside it. It’s like imagine a construction worker who not only lays brakes but arranges the blueprints too.

 

Speaker 1

06:28 – 06:31

I love that. So organized, But how’d the researchers figure that out?

 

Speaker 2

06:31 – 06:51

They used this really clever trick with a chemical called hexanediol. It disrupts certain cell structures, the ones that are more fluid, like oil separating from water. And what happened, when they treated cells with it, the MKLP1 and the RNA in the midbody, they spread out. But the microtubules, the rigid parts, they stayed put.

 

Speaker 1

06:51 – 06:55

It’s like shaking a snow globe, right? Snowflakes fly around, but the globe itself stays the same.

 

Speaker 2

06:55 – 07:04

Exactly. What that tells us is the RNA and MKLP1 are held together in this dynamic, liquid-like structure. Scientists call it a phase-separated condensate.

 

Speaker 1

07:04 – 07:12

So the midbody’s got these rigid microtubules and then this fluid compartment where the RNA and MKLP1 are doing their thing. Why is that important?

 

Speaker 2

07:12 – 07:31

It helps us understand how the midbody is put together, how MKLP1 interacts with the RNA. Think about it. You wouldn’t just throw your tools and blueprints in a pile, right? You’d have different areas for storage, work, organization. The midbody seems to work the same way, different compartments, different functions.

 

Speaker 1

07:31 – 07:41

I’m really starting to get a sense of just how complex these mid-bodies are. Way more than just cellular junk, more like a whole hidden city bustling with activity.

 

Speaker 2

07:41 – 07:48

That’s a great way to put it. And you know, there’s another layer to this. Remember how we were talking about when translation starts up again in the midbody, that Mg1 transition?

 

Speaker 1

07:48 – 07:50

The after party, right. What about it?

 

Speaker 2

07:50 – 08:01

They found that burst of translation in the midbody, it happens right at that transition point. Like the cell waits for that exact moment before it flips the switch on protein production in the midbody.

 

Speaker 1

08:01 – 08:05

That timing is incredible. It’s so precise. How could they even tell that was happening?

 

Speaker 2

08:05 – 08:25

They used a fancy technique called sunset labeling. It lets you actually see where proteins are being made in real time. And by lining that up with other things that happen at the Mg1 transition, like the nuclear envelope performing, the chromosomes unpacking, they were able to confirm it. Midbody translation happens right at that crucial moment.

 

Speaker 1

08:25 – 08:31

Wow, it’s amazing we can actually see these things happening inside a cell, like having a front row seat to a molecular dance.

 

Speaker 2

08:31 – 08:38

It really is. It shows you how powerful these scientific tools are, how they can help us uncover the mysteries of life.

 

Speaker 1

08:38 – 08:47

This is all mind-blowing, but I have to ask, why should we care about these tiny mid-bodies and their RNA secrets? What does it all mean for us in the big picture?

 

Speaker 2

08:47 – 09:03

Ah, the million-dollar question. This research is still pretty new, but the implications could be huge. If this RNA communication system is as important and widespread as it seems, it could change how we approach everything. Development, disease, even evolution.

 

Speaker 1

09:03 – 09:06

Okay, I’m ready for the big picture. What are we talking about here?

 

Speaker 2

09:06 – 09:20

Let’s start with development. Cells need to communicate to build tissues, organs, all that. Imagine these MBRs, full of RNA instructions, building proteins, acting as messengers to coordinate how cells behave during development.

 

Speaker 1

09:20 – 09:25

So, they’re not just leftovers. They could be key players in how our bodies are actually built.

 

Speaker 2

09:25 – 09:39

Exactly. And then there’s disease. Remember the oncogenes. If midbodies are involved in cancer, maybe by sending signals for out-of-control growth or helping cancer cells hide from the immune system, that opens up whole new avenues for research.

 

Speaker 1

09:39 – 09:42

So, targeting these mid-bodies could be a way to fight cancer.

 

Speaker 2

09:42 – 09:54

It’s a possibility. Lots more research is needed. But it’s not just cancer. This research could apply to any disease where cell signaling goes wrong. Autoimmune disorders, neurodegenerative diseases, it’s a whole new frontier.

 

Speaker 1

09:54 – 10:02

This is huge. We could be rewriting textbooks here. But you mentioned evolution too. How do these mid-bodies fit into our understanding of how life evolved.

 

Speaker 2

10:02 – 10:25

Think about it. This mid-body RNA system, it’s tied to cell division. That’s 1 of the most basic processes of life, right? If this communication system is as ancient as it seems, it could tell us something about how multicellular life came about, how cells learn to work together, specialize, create complex organisms. Studying mid-bodies could be like looking back into the deep history of life itself.

 

Speaker 1

10:25 – 10:35

Wow. That’s a lot to take in. We started with cellular junk, and now we’re talking about cancer, stem cells, new way cells communicate, and even the evolution of life.

 

Speaker 2

10:35 – 10:40

And there’s 1 more twist to this story. Remember how we talked about translation being mostly shut down during mitosis?

 

Speaker 1

10:41 – 10:44

Yeah, like the cell hits the pause button while it’s dividing. Why?

 

Speaker 2

10:44 – 10:55

Well, they found that there’s this 1 gene, and it seems to play a big role in controlling translation within the mid-body. And here’s the crazy part. It’s a gene that’s usually associated with brain function.

 

Speaker 1

10:55 – 11:00

Wait, a brain gene? Doing stuff in the mid-body? Now that’s a surprise. Which gene are we talking about?

 

Speaker 2

11:00 – 11:13

It’s called ARC, short for activity regulated cytoskeleton associated protein. Yeah. Scientists thought it was mainly a brain thing, important for, you know, how our brains learn and form memories, all that synaptic plasticity stuff.

 

Speaker 1

11:13 – 11:23

So we’ve got a brain gene involved in what’s going on in the mid-body, which itself is involved in all this other crucial stuff, that’s wild. How did they even discover that connection?

 

Speaker 2 11:23 – 11:33

They used this technique called Sereno knockdown. Basically a way to silence a specific gene, like flipping a switch to turn off a light.

 

Speaker 1

11:33 – 11:37

I get it. So they silenced the ARC gene to see what it was doing in the mid-body.

 

Speaker 2

11:37 – 11:46

Exactly. And the result, well, they were pretty clear. When ARC was silenced, translation in the mid-body, it went way down. Like, ARC is the conductor of the orchestra, you know?

 

Speaker 1

11:46 – 11:49

I see. So without ARC, no music.

 

Speaker 2

11:49 – 11:49

Pretty much.

 

Speaker 1

11:49 – 12:03

So we have this brain gene, ARC, playing a key role in how mRNAs are translated in the midbody, which itself could be a whole new way for cells to talk to each other. And It all comes back to this idea that mid-bodies are not just cellular junk.

 

Speaker 2

12:03 – 12:12

It really shows you how everything’s connected in biology. Who knew that studying cell division would lead to insights about the brain? Maybe even evolution itself.

 

Speaker 1 12:12 – 12:22

I know we’ve been talking a lot about RNA and translation and all that, and it can get kind of abstract. Is there a way to make this a little more down to earth?

Speaker 2 12:22 – 12:27

Let’s go back to our construction site analogy. Each midbody, each MB sum, it’s like a care package.

Speaker 1 12:27 – 12:34

Okay, I like that. What’s in these care packages? Tools, blueprints, snacks?

Speaker 2 12:34 – 12:43

Think of it as blueprints and instructions, all in the form of RNA. And those instructions, they can tell the cell that receives the package what to build, how to behave.

 

Speaker 1 12:43 – 12:50

So it’s like sending a message to your neighbor saying, hey, here’s how to build a deck, or here’s the recipe for that amazing cake you love.

 

Speaker 2 12:50 – 13:04

Exactly. And depending on what RNA is inside, those instructions could be for building proteins that are involved in growth, development, maybe even disease. And remember, the midbody is not just passively delivering these instructions, it’s actively translating them into proteins.

 

Speaker 1 13:04 – 13:08

Right, like a little workshop on the construction site churning out tools and materials.

 

Speaker 2 13:09 – 13:19

Amazing, right? It’s like these MB-SOMEs are little self-contained units. They can respond to their environment and adjust what they produce. Cells are so much more sophisticated than we used to think.

 

Speaker 1 13:19 – 13:28

It really makes you appreciate the complexity of life, even at the microscopic level. There’s a whole world of activity and communication going on that we’re just starting to understand.

Speaker 2 13:28 – 13:37

And that’s what makes this research so exciting. There’s so much more to discover. It’s like we’ve opened a door to a whole new unexplored territory in cell biology.

Speaker 1 13:37 – 13:46

It definitely feels like we’ve reached peak mind-blown status for today. But before we wrap up, is there 1 big takeaway you’d like to leave our listeners with.

 

Speaker 2 13:46 – 14:04

I think it’s this. Never underestimate the power of the small. We started talking about mid-bodies as cellular junk, and look where we ended up. They might be key players in some of the most fundamental processes of life. It just shows you there’s always more to learn, even the things we think are boring or insignificant.

 

Speaker 1 14:04 – 14:14

Well said. It’s a testament to the power of scientific curiosity, of questioning our assumptions. Who knows what other amazing discoveries are out there just waiting to be found?

 

Speaker 2 14:14 – 14:15

Can’t wait to find out.

 

Speaker 1 14:15 – 14:23

And on that note, listeners, keep those brains curious and those minds open. This has been the deep dive signing off.