Blake Hernandez

Let's start the week with this movie kindly shared by @loxstoplox.bsky.social
The movie shows a mouse embryo labeled with Formin-2-GFP and SPY650-DNA during nuclear envelope breakdown. Note the nuclear dilution of Formin-2-GFP immediately before the SPY650-DNA labeled chromosomes start compaction.

Rewriting the rules of cell division Microtubules get help from actin filaments during mitosis

New findings in Science demonstrate that successful mitosis may draw on more mechanisms than commonly assumed.

Learn more in this #SciencePerspective: scim.ag/4dFbqnp

Thank you Madhura!

Thank you so much Sam!

Actin sun.

🤣🤣🤣🤣

Thank you so much Pablo!

You appear to suggest that nuclear actin filaments disassemble during interphase. However, using phalloidin labeling we observed that nuclear actin density increases over the course of cell cycle progression.

Hi Robert, I’m assuming this is in response to Manuel’s post. I’m very familiar with your paper, nice work! Again, I disagree that the conclusions in my paper are similar to yours. In fact, here’s an example from your paper where we reach very different conclusions.

#FluorescenceFriday

Actin organizes chromosomes and microtubules to ensure mitotic fidelity in the preimplantation embryo Following fertilization, the preimplantation embryo undergoes successive rounds of cell division and must accurately propagate the genetic material to ensure successful development. However, early mam...

Paper link: www.science.org/doi/10.1126/...

A big thank you to our collaborators and the entire lab for their support inside and outside of lab! And huge shoutout to UPenn alum and actin guru @aaandmoore.bsky.social for key technical advice during the early stages of the project!!

I won’t spoil the details of the entire paper here, but we also identified a network of branched actin at the metaphase spindle periphery that modulates spindle size, offering a new explanation for the spindle scaling behavior seen in large acentriolar cells.

Surprisingly, network contraction is not driven by myosin-2. We instead found that contractile stress is generated by filament disassembly within the crosslinked network. We propose that after nebd, formin dilution from the nuclear region triggers filament disassembly and network contraction.

Actin to the rescue! A network of nuclear actin cables captures prophase chromosomes and contracts following nuclear envelope breakdown, gathering chromosomes towards the cell center. We propose that this mechanism of chromosome organization is required to achieve mitotic fidelity.

Even more puzzling, the first phase of mitotic chromosome organization occurs independently of spindle microtubules. So then what cellular component generates the necessary force to organize chromosomes?

It’s therefore puzzling that spindle assembly in the early embryo is highly inefficient, exemplified by comically disordered spindles during early mitosis (shown below).

In the classical view of mitotic cell division, the spindle apparatus maintains principal control of chromosome capture and alignment. Any breakdown in spindle function can result in chromosome mis-segregation, producing daughter cells with abnormal chromosome number.

I’m excited to announce that my paper describing non-canonical mitotic mechanisms in the early mouse embryo is out in @science.org ! (link at end of 🧵)

The first part of the paper is indeed closely aligned with great work from the Lenart lab. It’s also important to note that our paper focuses on mitosis, whereas much of the work you referenced centers on meiosis.

Regarding your comments on novelty: while it’s true that our work builds on the results of others (including your own), I disagree with the comparison to great work from the Schuh, Mogessie, or Grosse labs.

Hi Manuel, big fan of your work! I’d like to point out that the manuscript you reviewed is not the version that was ultimately published. Once you’ve had a chance to read the final version, I’d really appreciate hearing your thoughts.

Thank you Christophe!! I’ll post a thread later today

Actin does it again #cytoskeletonwar

Quincy gets my vote for Off the Wall alone!

Dynamic mitochondria labeled with PKmito #FluorescenceFriday

Thank you!

DM1A never disappoints 🤩 #FluorescenceFriday

What started as a brief chat with @buvansr.bsky.social and @vgelfand.bsky.social at the 2023 CellBio meeting @ascbiology.bsky.social has grown into our published collaborative work on single vimentin IF dynamics and organization in cells. Love when stuff like that happens.

Beautiful! COS-7?