EMBO Cell Polarity and Membrane Dynamics workshop is off to a good start - as always :) #EMBO

Altogether we propose that the fusion of VACs with the AMIS provides an efficient mechanism for the rapid specification of apical domain identity. In addition, Pals1 and PatJ appear to be critical for VAC fusion at the AMIS, possibly due to their role in regulating the apical actin cytoskeleton.

Finally, we asked how VAC exocytosis at the AMIS is regulated and found that loss of the Crb complex proteins Pals1 or PatJ results in the intracellular accumulation of VACs and severe defects in lumen formation. Apical actin levels and the apical cell cortex were markedly altered in PatJ KO cells.

We further present evidence that VACs arise from the internalisation of microvilli-enriched membrane pits at the ECM facing side of cell doublets. How these membrane pits are internalised and how VACs are trafficked to and fuse with the AMIS is currently unclear.

We then analysed lumen initiation in MDCK 3D cultures. Using LM and EM we identified intracellular VACs and observed fusion events of VACs with the Apical Membrane Initiation Site (AMIS). Interestingly, VAC fusion at the AMIS was again coordinated with the formation of cell-cell junctions.

Interestingly, our time-resolved proteome revealed distinct recruitment profiles of Rho and Ras GTPases, tight junction membrane and scaffolding proteins, as well as apical proteins, providing new insight into the temporal execution of cell polarity development.

This set of experiments demonstrated that apical lumens are initiated by the exocytosis of large intracellular organelles at nascent cell-cell contact sites. Such organelles contain a pre-assembled microvilli-rich cortex and are known as Vacuolar Apical Compartments (VACs), or apicosomes.

Another beautiful tight junction. This time with scale bar :)

Not bad for a conventionally fixed and dehydrated TEM sample. No HPF/FS. OTO method. Stains the kissing points quite nicely.

Still one of my favourite tomograms, recorded ages ago at NCMIR (UCSD). It shows interconnected networks of caveolae (labeled with a miniSOG probe) at the rear of RPE1 cells. Bummer we so far haven't been able to image such networks in larger cell volumes; it's a lot of membrane that's stored here.

Our data indicate that ARHGAP12 suppresses the activity of N-WASP to dampen actin assembly via Arp2/3 complex. This limits junctional tension and makes tight junctions more leaky. The story is currently under revision. Thanks to the two reviewers who have been very kind to us!

Woah. Bluesky seems to be much more than a much needed alternative to X. I didn't expect this big a science community here tbh. I love the start up packages; really cool to connect with so many people I never met or even heard of. Since I'm new to this, I'll briefly introduce my lab and what we do.