Ryszard Wimmer

✨ #FluorescentFriday ✨
SOX2-positive cells forming the heart of the developing human cerebellum 🧡, framed by a glowing outline of PAX6-positive neighbors 💙. A tiny but breathtaking glimpse into brain development under the microscope. 🧠💡

2D, but never flat — neural progenitors glowing blue & yellow, and me falling for biology all over again 😍

There is no better place to talk about Radial Glia Cells than on the beaches right under the Etna in Gardini Naxos @corticodevelopment.bsky.social !

DCHS1 Modulates Forebrain Proportions in Modern Humans via a Glycosylation Change Comparative anatomical studies of primates and extinct hominins, including Neanderthals, show that the modern human brain is characterised by a disproportionately enlarged neocortex relative to the st...

Excellent work from @silvianeuro.bsky.social lab on DCHS1 ! @mveronicapravata.bsky.social congratulations!
www.biorxiv.org/content/10.1...

DCHS1 Modulates Forebrain Proportions in Modern Humans via a Glycosylation Change https://www.biorxiv.org/content/10.1101/2025.05.14.654031v1

Our community is thrilled to have Dr. Ekin Ucuncu join the ReplicApril conversation with a guest post on how shared standards in stem cell research can help drive reproducibility forward.

sciencebank.com/development-... A cool and smooth blog post on stem cell use, validation, quality control and on how to share Your precious stem cells with others! #stemcells I hope You enjoy!

In the neon glow of the cortex, a Radial Glia stretched its long, guiding arm. Suddenly, a rogue cell snatched a piece of its scaffold, disrupting the neural highway. "Hey!" it pulsed, but the thief vanished into the synaptic shadows. The network flickered—order shaken. #fluorescentfriday

Delighted to have this out as a preprint! Thanks to all authors, especially @estherkli.bsky.social and @djabaudon.bsky.social for leading the work. If you are interested in how conserved genes played a part in evolving human brains, give it a read!

New preprint out from the lab, check out thread below!

While waiting on my paper to get rejected or accepted 🤗 I discovered that playing with clay is just a beautiful disconnection from everyday problems. Here is my first take at a flower-shaped candle ! #pottery #nature #flowers #qualitytime #science

I’m not even from the Crick, nor from England but I completely agree with the contents of the abstract !

I still remember try to make some of these tricks on Tony hawk when it came out on PC 🫠

Images and all scientific data needs a voice. @clarissebrunet.bsky.social is running a beautiful podcast in spannish called Ciencia en Voz Alta „Science Out Loud”. It’s a beautiful series of podcasts with scientists on spotify talking about their research! cienciaenvozalta.com
Enjoy! 🎧

🌟 Absolutely mesmerizing! The vibrant interplay of Sox2 in sky blue with proliferating neural stem cells creates a brilliant window into brain development. A perfect showcase of science meeting art—thanks for sharing this beauty! 🧠💡

Two independent translocation modes drive neural stem cell dissemination into the human fetal cortex The strong size increase of the human neocortex is supported by the amplification and the basal translocation of a neural stem cell population, the basal radial glial cells (or bRG cells). Here, using...

www.biorxiv.org/content/10.1...

Thank You! 🤗

Thank You! 😍

Two independent translocation modes drive neural stem cell dissemination into the human fetal cortex The strong size increase of the human neocortex is supported by the amplification and the basal translocation of a neural stem cell population, the basal radial glial cells (or bRG cells). Here, using...

Hello! My PhD pre-print is out on biorxiv, where in the Lab of @alexbaffet.bsky.social we managed to unravel how bRG (oRG) cells translocate and colonise the developing human brain. Interestingly features of these translocations are conserved in glioblastoma! Link : www.biorxiv.org/content/10.1...

I want to thank everyone involved in this work on top of Ryszard who did an amazing job. Laure Coquand, Amandine Di Cicco, Christophe Chehade, @clarissebrunet.bsky.social @pauline-lestienne.bsky.social, Julia Ladewig, Karin Forsberg-Nilsson, Fabien Guimiot and our fantastic imaging facility!

Using 9 different glioblastoma lines we show that IST and MST both occur, although not in all cells, reflecting the heterogeneity of these tumors. Strikingly, glioblastoma undergoing IST and MST did so using the same molecular mechanism as the ones identified here in bRG cells.

Finally, because past work form @bhadurilab.bsky.social and others had shown a facilitating similarity between bRG cells and glioblastoma cells (including the presence of MST), we tested the conservation of our mechanisms in these cells.

Therefore, microtubule related genes are more likely to affect human oSVZ expansion than actin-related ones.

So MST and IST are totally different mechanisms, but what is their relative contribution to bRG dissemination in the human fetal cortex? After extensive recording in fetal explants, Ryszard could show that IST contributes to 85% of the total basal movement, while MST contributes to 15%.

Mechanistically, we demonstrate that MST is dependent on the mitotic cell rounding pathway, that enables most adherent cells to round up for proper chromosome segregation through an increase of the cell cortex stiffness. Knocking down ERM proteins (Ezrin-Radixin-Moesin) or Vimentin all alter MST.

We next focused our attention on MST and, using Sir-tubulin dyes, first showed that it occurred after nuclear envelope breakdown, and is therefore a mitotic spindle translocation event!!! I find this crazy, and to our knowledge quite unique in biology (so far...).

Together, this microtubule-dynein-LIS1-LINC pathway generates pulling force and the nucleus, for translocation. Interestingly, this mechanisms is different from INM in aRG cells, but similar to nucleokinesis in neurons. Neuronal migration disorders may therefore also result from bRG cell defects.

We demonstrate that IST is dependent on the dynein motor and its activator LIS1. Accordingly, IST is severely affected in LIS1-patient derived organoids (Lissencephalic). We also show that the dynein-LIS1 complex is recruited to the nuclear enveloppe (and underlying Lamins) via the LINC complex.

On top of identifying the mechanism for MST, we realised that bRG cells also translocate during interphase, a process we call Interphasic Somal Translocation (IST). We show that IST is microtubule dependent and actomyosin independent, while MST is actomyosin-dependent and microtubule independant.

bRG cells were known to translocate rapidly during mitosis, a process called Mitotic Somal Translocation (MST). This translocation relies on acto-myosin contractility and was identified by the Kriegstein lab.

Great work from @ryszardwimmer.bsky.social, who live imaged and manually tracked over 11,000 human bRG cells, for 48-96 hours 😱. (I feel bad)
What he realised is that bRG cells have two, totally independent modes of migration, for which he managed to identify the molecular mechanisms.