Ralf Jansen

Molecular basis of polyadenylated RNA fate determination in the nucleus Eukaryotic genomes generate a plethora of polyadenylated (pA+) RNAs[1][1],[2][2], that are packaged into ribonucleoprotein particles (RNPs). To ensure faithful gene expression, functional pA+ RNPs, in...

How are RNAs sorted for export vs. degradation in the nucleus? In collaboration with @heick.bsky.social’s lab we (@clemensplaschka.bsky.social and @juliusbrennecke.bsky.social labs) discovered a direct mechanistic link between the export and decay machineries: www.biorxiv.org/content/10.1... (1/x)

I am excited to announce that I will be moving to IMB Mainz next year! The Winter call for the IPP PhD program is now open; if you are interested in maternal #mRNA regulation and #translation in early vertebrate development, please apply! Deadline: 16 October.

More info: www.imb.de/students-pos...

Love RNA biology?

Join us to explore the piRNA pathway with structural and genetic approaches (see 👇👇).

PhD student/postdoc position co-supervised by Clemens Plaschka & myself.

DM or email us if you’d like to know more!

@vbcscitraining.bsky.social @imbavienna.bsky.social @impvienna.bsky.social

My first first-author paper is out!🎉
Here we propose a model where a silencing complex, PIWI*, assembles on target RNAs to recruit effectors and shut down transposon activity.
Huge thanks to the Brennecke and Plaschka labs, especially Julius and Clemens, and all co-authors!

PIWI clade Argonautes are essential for transposon silencing. Without them, animals are sterile due to massive transposon activity.

But how does piRNA-guided target interaction translate into silencing?

PhD student Júlia Portell Montserrat has an intriguing answer

www.cell.com/molecular-ce...

Close inter-lab collaborations with shared PhD students and postdocs are the future!
Julia is the hero of this work, she is currently looking for postdoc labs …

Target RNA recognition drives PIWI∗ complex assembly for transposon silencing Portell-Montserrat et al. reveal that target RNA recognition by PIWI-piRNA complexes triggers the assembly of conserved PIWI∗ complexes, molecular platforms that recruit silencing effectors in both the nucleus and cytoplasm. This mechanism, conserved across animals, explains how piRNA pathways couple target recognition to transposon silencing.

Target RNA recognition drives PIWI∗ complex assembly for transposon silencing

New paper by our Plaschka lab with Brennecke’s lab at IMBA!

Researchers at the Vienna BioCenter have solved a 20-year-old mystery in genome biology, revealing how PIWI proteins engage partner molecules to silence “jumping genes” that threaten genetic stability.

So happy to see the PhD work of Emilio Santillán published—what an amazingly elegant piece of work!!
Working with him and Luisa at the IMP was a great and formative experience.

1/ How do animals develop immunity against a newly encountered transposable element from scratch? Our study reveals that the mobility of TEs is their Achilles heel, allowing hosts to develop a powerful small RNA-mediated silencing response.
www.biorxiv.org/content/10.1...

My colleagues Baptise Rafanel et al. investigated how a newly invading transposon can be silenced. They found that not only antisense insertions in piRNA clusters such as flamenco, but also insertions in the 3‘UTR of genes can drive potent silencing.

Pls. share widely

Calling all transposon fans & lovers of genetic innovation

MOBILE GENOME welcomes you in Heidelberg, Nov. 4–7 2025

→ Vibrant & friendly community
→ Cutting-edge talks from mechanisms to physiology
→ Plenty of surprises (TEs never stop innovating)

submit abstract by July 29

We found a new asymmetry in the large-scale chromosome structure: sister chromatids are systematically shifted by hundreds of kb in the 5′→3′ direction of their inherited strands! The work was led by Flavia Corsi, in close collaboration with the Daniel Gerlich lab.
www.biorxiv.org/content/10.1...
1/

ChAHP Silences SINE Retrotransposons by Inhibiting TFIIIB Recruitment Short interspersed nuclear elements (SINEs) are abundant non-autonomous transposable elements derived from RNA polymerase III (POL III)-transcribed short non-coding RNAs. SINEs retain sequence feature...

📖 Happy to share our recent preprint! www.biorxiv.org/content/10.1... We discovered how SINEs are kept silent: the ChAHP protein complex acts as a molecular brake on POL III transcription retrotransposons. A 🧵:

The fascinating work spearheaded by Kirsten Senti on the diversification and adaptation of endogenous retroviruses in the host gonad 'ecosystem'' is officially published.

I freaking 😍 this paper. The ecology of the genome is one thing. The ecology of the Drosophila ovary another.

🚨📢 New paper alert!
A study led by Kirsten Senti and Julius Brennecke offers new insights into how ancient endogenous retroviruses diversified to exploit different cell “niches” in the fruit fly ovary, and how the host’s defenses adapted in return. https://imba.science/Brennecke_EMBOJ

REFEREE 1: “I conclude with a simple, direct statement - this is the best paper I have read all year!”
#TransparentPeerReview

Co-evolving infectivity and expression patterns drive the diversification of endogenous retroviruses
@juliusbrennecke.bsky.social et al

www.embopress.org/doi/full/10....

The @viennabiocenter.bsky.social PostDoc Program call is now open! We have 16 fully-funded positions for scientists with a PhD in biology, chemistry, physics, bioinformatics etc.

Apply here: training.vbc.ac.at/post-docs/vi...

#VBCPostDoc

Link to Peter‘s thread:
bsky.app/profile/germ...

Highly interesting work from Riedelbauch et al. from Peter Andersen‘s Lab @germline.bsky.social

YouTube video by Johan Gibcus Rules of Engagement

Earnshaw, Goloborodko, Dekker & Mirny labs are excited to present our latest work, "Rules of engagement for condensins and cohesins guide mitotic chromosome formation" - now accepted!!
www.science.org/doi/10.1126/...
A short clip describing the key results:
www.youtube.com/watch?v=pmvO...

A thread from the Postdoc who led the work on bacterial Telomeric transposons. A wonderful collaboration with the Barabas lab. Officially out in the journal today!

IMBA is recruiting a Junior Group Leader! Are you interested in starting your own lab, pursuing curiosity-driven basic research in the life sciences? Apply now to our group leader position. The deadline is May 28. Link is below.

1. For the past thirty years I've had the best job in the world.


I've had the opportunity to follow my curiosity; explore the workings of nature and society; mentor students and junior colleagues in the same process; and teach generations of students about it all.

Drosophila follicle showing retrotransposons (pink & yellow) expressed in somatic cells infecting the oocyte

1/ Transposable elements are often called "jumping genes" because they mobilize within genomes. 🧬
But did you know they can also jump 𝘣𝘦𝘵𝘸𝘦𝘦𝘯 cells? 🤯
Our new study reveals how retrotransposons invade the germline directly from somatic cells.
www.biorxiv.org/content/10.1...
A short thread 🧵👇

I am thrilled to share our story online at @cellpress.bsky.social . Big thanks to all authors: Zhiping, Bill, @lubanlab.bsky.social, Keith & bluesky-less!

authors.elsevier.com/c/1kjdaL7PXu...

How to tame a genome invader? It takes wild koalas 🐨🐨 to learn it.
#Retrovirus #koala #piRNA

More below 👇

"Scientists have to organize, they have to protest, they have to make their case to the public. They must never give in." Quote from Paul Nurse (2001 Nobel) from upcoming interview in @annualreviews.bsky.social with him and Bruce Alberts (former President NAS). @standupforscience.bsky.social‬ today

Beautiful work on the copia retrotransposon by Sven Klumpe (ex-MPI, soon IMBA/IMP) and Kirsten Senti from the Brennecke Lab!

- EMBL with EMBL outstations
- Max Planck institutes in Germany (e.g. Dresden, Goettingen)
- Vienna BioCenter (IMP, IMBA, GMI, Max Perutz Labs)
- FMI Basel
- ETH Zürich
- CEITEC Brno
- CRG Barcelona
- Hubrecht Institute (Netherlands)
- EPFL Lausanne