Meghan Morrissey

We had a fantastic experience @jcb.org . The editors were fair and thoughtful, and the review process significantly strengthened both papers. 🙏 Would highly recommend for any junior faculty who dont want to mess around with lengthy review processes.

CD47 inhibits phagocytosis through Vav dephosphorylation Miller et al. demonstrate that the CD47 signaling pathway prevents phagocytosis through dephosphorylation of the Rac GEF Vav. Cancer cells and synthetic ta

Second, Wyatt Miller clarifies the downstream signaling pathway that the "Don't Eat Me" signal CD47 uses to stop phagocytosis. A very satisfying answer to a major question we've had since I started my postdoc, with lots of interesting implications doi.org/10.1083/jcb....

We have TWO papers out in @jcb.org this month! 🎉

First, @kirstin-rollins.bsky.social showed that macrophages nibble adherent target cells, like the ones found in solid tumors, instead of phagocytosing. Amazing movies from @sareenfiaz.bsky.social

doi.org/10.1083/jcb....

Thank you!! Ill be at ASCB this year, we should catch up!

In @jcb.org, @mmorrissey.bsky.social lab demonstrate that the CD47 signaling pathway prevents #phagocytosis through dephosphorylation of the Rac GEF Vav. Cancer cells & synthetic targets w/ CD47 can still be phagocytosed less efficiently through a Rho-dependent mechanism rupress.org/jcb/article/...

Miller, @mmorrissey.bsky.social et al. demonstrate that the CD47 signaling pathway prevents #phagocytosis through dephosphorylation of the Rac GEF Vav. Cancer cells & synthetic targets with CD47 can still be phagocytosed less efficiently through a Rho-dependent mechanism. rupress.org/jcb/article/...

Thank you!!

Could not agree more 😁

@kirstin-rollins.bsky.social, @mmorrissey.bsky.social et al show that #macrophages attack adherent cells using #trogocytosis instead of #phagocytosis. Reducing adhesion increased phagocytosis. Mitotic cells, which disassemble adhesions, are more vulnerable to phagocytosis rupress.org/jcb/article/...

#Macrophages are presumed to attack antibody-opsonized #cancer cells by #phagocytosis. In @jcb.org, @kirstin-rollins.bsky.social, @mmorrissey.bsky.social et al find that macrophages attack adherent cells using #trogocytosis, or cell nibbling, instead of phagocytosis. rupress.org/jcb/article/...

Cool paper, congratulations!

Excited by phagocyte biology? Still making summer conference plans? The Phagocytes GRC has an amazing lineup of invited speakers and many opportunities for talks from submitted abstracts. Apply soon for full consideration! www.grc.org/phagocytes-c...

🎉🎉🎉

I have been trying to ID the direct targets of these phosphatases since I started studying CD47 as a postdoc, but before this had only managed to find downstream targets. I am THRILLED to have a more satisfying answer.

With these clues, Wyatt pinpointed a specific cytoskeletal regulator that is dephosphorylated by SHP-phosphatases bound to SIRPA (CD47 receptor)... Vav1, a Rac GEF! Hyperactivating Vav1 or Rac meant macrophages could phagocytose cancer cells with CD47.

If macrophages managed to eat a target, it was through a slower sinking phagocytosis...

But when we added CD47, this type of phagocytosis failed...see how the macrophage keeps trying to extend membrane but doesn't quite make it

Macrophages usually reach out to phagocytose IgG coated targets... see the cell extending membrane out and around the bead

CD47 prevents Rac-mediated phagocytosis through Vav1 dephosphorylation CD47 is expressed by viable cells to protect against phagocytosis. CD47 is recognized by SIRPα, an inhibitory receptor expressed by macrophages and other myeloid cells. Activated SIRPα recruits SHP-1 ...

Wyatt Miller's thesis project is on bioRxiv! We describe the signaling cascade that allows the 'Don't Eat Me' signal CD47 to inhibit phagocytosis. www.biorxiv.org/content/10.1...

Target cell tension regulates macrophage trogocytosis Macrophages are known to engulf small membrane fragments, or trogocytose, target cells and pathogens, rather than fully phagocytose them. However, little is known about what causes macrophages to choo...

This supports the idea that target cell's biophysical properties regulate the decision to trogocytose instead of phagocytose, as Caitlin Cornell @fletcherlabucb.bsky.social proposed in their recent preprint: doi.org/10.1101/2024.12.02.626490

Excited to share @kirstin-rollins.bsky.social thesis project! 🥳Why do macrophages sometimes eat a whole cell, and sometimes just nibble off pieces? We found that if the target cell is stuck to a substrate or part of a 3D tissue, the macrophage nibbles instead of phagocytosing the whole cell.

Trump & Musk are making massive cuts to the National Institutes of Health.

I know there is a lot going on right now, but this is one of worst things they have done so far, will affect cancer research and trials, the search for cures, innovation and competitiveness, our universities. Your lives.

Thank you!!

Thank you! 😀

Thank you! 😀

Extremely grateful to Damon Runyon for this funding, especially with todays news on NIH grants. See a green macrophage nibbling on a pink cancer cell 👇

@mmorrissey.bsky.social is investigating how immune cells known as macrophages might be induced to “nibble” cancer cells to death through a process called trogocytosis.

Congratulations to the recipients of the 2025 Damon Runyon-Rachleff Innovation Award! Five exceptional scientists received initial grants, and three previous awardees were given Stage 2 support to continue their critical work. Read more: www.damonrunyon.org/news/entries...

Cartoon showing that phagocytic receptor availability can be modulated through multiple mechanisms. Receptor availability can be modulated by (A) transcriptional changes affecting receptor expression levels, (B) receptor internalization, which reduces available ligand-binding sites, (C) ectodomain shedding, which can cause sequestration of ligands away from signalling domains, (D) post-translational modifications, such as conformational changes that affect ligand binding affinities, and (E) glycosylation that can affect receptor or ligand accessibility.

@annalisebond.bsky.social and @mmorrissey.bsky.social @ucsantabarbara.bsky.social review the biochemical and biophysical mechanisms that macrophages use to tune phagocytic appetite.
journals.biologists.com/jcs/article/...

Thrilled to share our @sciimmunology.bsky.social paper! We report that rodent PD-1 is weaker than human PD-1 (reduced ligand binding & signaling) & lacks a conserved vertebrate motif. Humanizing mouse PD-1 disrupts T cell anti-tumor responses, raising many questions. science.org/doi/10.1126/...