3rd: NIPBL does not spread out along with cohesin when WAPL is depleted. We speculate that this may be one of the reasons why C. elegans cohesin has a shorter processivity.

2nd: Interestingly, the average cohesin mediated loop size is smaller on the X compared to autosomes. We hypothesize that condensin DC is a stronger extruder/wins over cohesin.

1st: a figure for different scales of 3D genome organization in c elegans. Autosomes are roughly separated into two arms and a center, TADs are made by condensin DC on the X chromosomes, cohesin makes DNA loop domains called jets/fountains on all chromosomes

Together, our results support a model in which active enhancers recruit cohesin to loop extrude, creating chromatin jets across transcribed gene domains.

With a one-hour cohesin or wapl knockdown, we did not see an effect on RNA Pol II binding by ChIP-seq. For aficionados: NIPBL binding also didn’t change upon cohesin knockdown, suggesting it doesn’t go along with cohesin in worms.

Taking a close look at the trajectory of individual jets was fun, and in a couple of examples, we see that the loading and clashing of cohesin molecules shape the 3D interactions.

We identified a cohesin mediated Hi-C feature that is like the mammalian “chromatin jets” (Guo et al. 2022). The jets disappeared in cohesin depletion and extended in WAPL depletion. Jet origins coincide with active enhancers and the cohesin loader NIPBL.

Worms are great for knocking down proteins using auxin inducible degradation. So, we did this for SMC-3 subunit of cohesin and its negative regulator WAPL1 in the soma.

dumpiest ever!

happy caturday