😂 both versions can be equally accurate.

If anyone is unable to fully access the paper with the link above, please use this one: authors.elsevier.com/c/1ksln3BtfH...

And of course, a HUGE thank you to the whole team who made this possible! Special shoutout to Yao (co-first author & SAP-seq god), Jess (bioinformatics guru), Marwan (Lippi lab mouse whisperer) and our fearless visionary leaders Ian and Giordano.

We greatly appreciate the support provided by the DNC vivarium staff, the core services at @scripps.edu, and @eclipsebio.bsky.social! Thank you to our editor and reviewers for their constructive feedback and a smooth, collaborative review process that helped strengthen the paper.

We think that our findings are just the tip of the iceberg, and we hope that DD-T6B, SAP-seq and our approach of dissecting miRNA-target networks can contribute to future miRNA research! Also, many exciting projects brewing in the lab on development, neural plasticity and aging. 👀

Importantly, studying miRNA-target networks in developing PCs is highly relevant for understanding neurodevelopmental disorders, such as autism spectrum disorder, where PCs are particularly vulnerable. Thank you to @autismspeaks.org for supporting this project!

Our findings suggest that adding cell type-specific layers of post-transcriptional regulation on shared transcriptomes can give rise to distinct structural features. Notably, it seems that the PC miRNA-target network acts as a brake on programs that limit dendritogenesis.

Finally, we investigated select targets that were more regulated by miRNAs in PCs compared to PNs. Strikingly, we found that repression of Prag1, Vash1, Shank3 and En2 is critical for PC dendritic and CF synaptic development.

We then compared the miRNA-target networks of PCs vs pyramidal neurons (PNs) and found subsets of targets similarly expressed in both but differentially targeted by miRNAs in PCs or PNs, hinting at transcription-independent post-transcriptional programs instructing development.

Intriguingly, we found the PC-specific miR-206 to be necessary and sufficient for elaborate dendritic arborization, a characteristic feature of PCs . We also found roles for miR-206 and miR-133 in CF synaptogenesis!

Yao and Ian developed a new method SAP-seq, which allowed us to map miRNA-target networks in rare cells like PCs for the first time! 🤯 With maps from developing PCs, we asked how PC-specific miRNAs and targets might instruct its unique dendritic arborization and CF synapses.

To get into the underlying mechanisms, we started a great collaboration with Ian MacRae’s lab at Scripps. We developed and characterized a conditional SpyTag3-AGO2 knock-in mouse line that is minimally disruptive to AGO2 function.

Curious about the “when” of miRNA function, we developed an inducible and reversible version (DD-T6B), which allowed us to identify critical windows of miRNA regulation for PC dendritic vs CF synapses (without the confounding factor of cell death caused by extended miRNA loss)

So, we repurposed the peptide T6B (from the Meister lab) for neurons to induce fast miRNA loss of function and found that contrary to prior KO studies, miRNAs are critical for PC dendritic development and climbing fiber (CF) synapse formation. (See the paper for in-depth characterization of T6B)

During my PhD, I became fascinated with Purkinje cell (PC) dendritic trees and wanted to understand if/how miRNAs were regulating its growth. Digging through the literature we realized that existing tools for miRNAs were just not sensitive enough to access PC development. 🤔

Hello, I’m a postdoc at Scripps Research in San Diego and a fan of your night science podcast. This sounds exciting! I would love to learn more about your events and what you are envisioning for Postdoc Night Science and potentially help kick it off here in SD!