Roux Lab, Geneva

New method paper out today on FLIM analysis with Flipper-TR.
We discuss fitting strategies, common pitfalls, and quantitative interpretation for measurements.
First corresponding/last authorship for me!
Free link:
authors.elsevier.com/a/1me2hHRzCb...
Thanks to @rouxlab.bsky.social and Tithi Mandal!

This monday we had our monthly Sciences Club.
Here Cesar Bernat is showing his work on CHMP1A in mammalian cells in the @rouxlab.bsky.social !

#postdoclife

I am super happy and honored to see some of my movies making it into the NYT. I hope everybody enjoys watching them go as much as I do!

So grateful to @epimechfc.bsky.social for citing our work! It’s a classic from the lab, forever thanks to @colomlab.bsky.social

thanks for showing this movie! The gradients of tension reorient while migrating cells change directions.

All what you want to know about flipper probes without daring asking

Exhaustive guide about Flipper TR FLIM analysis we made with Tithi Mandal and @rouxlab.bsky.social very soon in the methods in Enzymology series edited by @jeremybaskin.bsky.social

You should also read Juanma’s paper, which visualizes membrane tension gradients in migrating and non-migrating cells! rdcu.be/e2u20
It also shows that flipper truly reports tension, but that response varies with lipid composition.

Roffay, C., Molinard, G., ..., & Roux, A. (2021). Passive coupling of membrane tension and cell volume during active response of cells to osmosis. Proceedings of the National Academy of Sciences of the United States of America, 118(47), e2103228118. #EpithelialMechanics
buff.ly/r1Hj7F6

Guillaume Pernollet shows that epithelial cells adjust their shape to locally flatten, forming scutoids for any geometry, changing our view of cell packing. Thanks to all! @clairedessalles.bsky.social @juanmagararc.bsky.social @sciencesunige.bsky.social
www.biorxiv.org/content/10.6...

@marineluciano.bsky.social recreates intestinal Villi geometry by growing epithelial cells on wavy rolling substrates. Unexpected intrication of curvature effects is observed. Thanks to all! @caterinatomba.bsky.social @sgabriele.bsky.social @sciencesunige.bsky.social
www.biorxiv.org/content/10.6...

Long-range chemical signalling in vivo is regulated by mechanical signals - Nature Materials Tissue stiffness mediated by Piezo1 is shown to regulate the expression of diffusive guidance cues in the developing Xenopus laevis brain, revealing a crosstalk between mechanical signals and long-ran...

Paper alert: Our study led by @evapillai.bsky.social and @sudimukherjee.bsky.social showing that mechanical properties of the #brain actively shape the molecular landscape during development and #axonpathfinding is finally out! www.nature.com/articles/s41... @pdncambridge.bsky.social @fau.de @MPZPM

congrats Joshua!

A great start to 2026! It was a pleasure to present my work on membrane asymmetry in the @rouxlab.bsky.social at the Geneva Chemistry and Biochemistry Days. It was also an honor to receive the Best Oral Presentation in Life Science!

A fantastic opportunity to work in Geneva if you are in the field of origins of life!

Today, our animation synthesizing decades of research on actin-mediated endocytosis in budding yeast was published:
journals.biologists.com/jcs/article/...

The result of a fantastic Iwasa-Drubin lab collaboration.

@margotriggi.bsky.social @jiwasa.bsky.social
movie.biologists.com/video/10.124...

Photo de moi et Élisabeth

Un très grand plaisir d'avoir pu enfin (après 5 ans) voir @elisabethbik.bsky.social en face à face à l'UNIL.

Elle y donne en plus un séminaire aujourd'hui.

All credits to the dreamteam that made this possible! what a pleasure and honor working with these people! 🥰
@diorgeps.bsky.social @mhakala.bsky.social @juanmagararc.bsky.social @joshuatran.bsky.social @mudgal17.bsky.social @Carlos Marcuello @Andrea Merino

The crucial test: We fused Heimdall Hofund to a fission-defective yeast ESCRT-III protein (Did2). This chimera restored Mup1 trafficking to vacuoles back to wt! A short amphipathic helix, present in Asgard and retained as fragments in eukaryotes, acts as a minimal membrane fission trigger!

Eukaryotic ESCRT-IIIA paralogs, known to form heteropolymers, retain Hofund elements at their N-termini.
In yeast, mutating these elements blocks ESCRT-III-dependent Mup1 transport to vacuoles.
So these elements matter in eukaryotes too.

Is this Asgard-specific, or conserved with their eukaryotic paralogs?
Hard to tell, since the exact molecular mechanism of fission by eukaryotic ESCRT-III remains blurry, probably due to its complexity.
Let’s figure it out!

Meet Hofund, the N-terminal amphipathic helix of 15 aa in Heimdall ESCRT-IIIA (named after Heimdall’s sword).
How do we know Hofund is the molecular trigger for fission?
Remove Hofund → ESCRT-IIIA loses fission activity.
Add Hofund alone → uncontrolled fission.

Through membrane fission! We show in vitro that the Asgard Heimdallarchaeota (Heimdall) ESCRT-IIIA subunit is inherently capable of triggering fission upon subunit turnover driven by ATP hydrolysis by Vps4.
And the key question: what actually destabilizes the membrane when ESCRT-IIIA turns over?

An Asgard archaeon with internal membrane compartments The emergence of eukaryotes from a merger between an archaeon and a bacterial cell ∼two billion years ago involved a profound change in cellular organisation. While the order in which different featur...

In a recent work, @buzzbaum.bsky.social and colleagues showed an Asgard archaeon with internal vesicles.
www.biorxiv.org/content/10.1...
How might Asgard ESCRT-III have contributed to compartmentalization?

Fantastic work from Javier @javierespadas.bsky.social in collaboration with @buzzbaum.bsky.social and @kaksonen.bsky.social labs, thank you Chris Toret, thank you Diorge @diorgeps.bsky.social!

Thanks to all the team at @rouxlab.bsky.social and abroad: @pauguillamat.bsky.social @caterinatomba.bsky.social @giodang.bsky.social @colomlab.bsky.social @lizhinde.bsky.social @javierespadas.bsky.social and many more

Overall, the work shows that tension gradients arise from the combination of actin dynamics and strong cell–substrate adhesion, rather than from migration itself.
Link: rdcu.be/eRTQA

We accompanied this dynamic live Flipper-TR FLIM imaging with lipid diffusion analysis, spatial lipidomics (shown below), and cool in vitro reconstitutions of tension gradients using supported lipid bilayers that are expanding

A key result: adherent cells maintain long-range membrane tension gradients even when they are not migrating! (micropatterned cells below)
In contrast, non-adherent migrating cells *do not* show these gradients.

Congrats Juanma! Thanks to all for your contributions in the long journey!