NTR: tuft

[Caroline-99]

Please provide as much information as you can:

• Suggested term label: tuft

• Definition (free text)

A dense cluster of elongated, thick microvilli on the apical surface of a tuft cell in epithelial tissues, such as the intestine and respiratory tract; extending into the lumen and containing a network of microfilaments and microtubules, these microvilli support the cell’s chemosensory role.

• Reference, in format PMID:####### (REQUIRED) PMID: 15817800 PMID: 35237268

• Gene product name and ID to be annotated to this term Advillin (AVIL) - actin-binding protein that is specifically expressed in intestinal tuft cells and has been shown to be strongly localised to their apical tuft in mouse models. Advillin expression has been confirmed in human intestinal tuft cells but the specific subcellular localization of advillin in human tuft cells has not been explicitly identified or described. (PMID: 32483224)(PMID: 37863104)(PMID: 39358509)

• Parent term(s) cluster of actin-based cell projections

• Children terms (if applicable) Should any existing terms that should be moved underneath this new proposed term?

• Synonyms (please specify, EXACT, BROAD, NARROW or RELATED)

• Cross-references brush cell

• For enzymes, please provide RHEA and/or EC numbers.

• Can also provide MetaCyc, KEGG, Wikipedia, and other links.

• Any other information

[cmungall]

Thanks @Caroline-99!

Can you say more about how this differs from a brush border? My understanding is that they are analogous, with tufts playing more of a sensory role. However CL seems to treat brush cell and tuft cell as synonyms?

I think these terms present some interesting challenges for GO. We have actin skeletons represented at different scales from the filaments themselves up to microvillus then up to larger structures like the brush border. We need a better strategy to make sure these are consistently populated. We also have some distinctions that seem dubious like brush border v brush border membrane. This seems like a good area for CL and GO to work on together

[dosumis]

Brush cell and tuft cell are used synonymously for chemosensory cells that have a very distinctive microvilli-based structure structure on their apical membrane (we may be able to add more details of what makes the structure distinctive). 'Brush' in this case is not related to brush border - which consists of very dense microvilli covering the apical membrane and specialised for absorption. In the case of the small intestine, the tuft cells are interspersed among enterocytes which have a brush border.

[Caroline-99]

I have added more details in the definition to make the apical tuft's unique features more distinctive -

A dense cluster of elongated, thick microvilli on the apical surface of tuft cells in epithelial tissues, such as the intestine and respiratory tract. The apical tuft extends further into the lumen than typical microvilli, featuring larger, more compact projections with unique actin cores that penetrate deep into the cytoplasm, often reaching the perinuclear region. This distinctive structure, rich in microfilaments and microtubules, supports the chemosensory functions of the cell.

@cmungall @dosumis Does this help clarify the difference from the brush border? Let me know if there’s anything else that could be clearer - I can also add more details in the comments section, comparing it directly to the brush border .