Thread: Multi-lobed nuclei

Does anyone know what the purpose of a multi-lobed nucleus is?

Several cell types in our own immune systems have such nuclei, such as this neutrophil:

It's a good question, I couldn't find an answer in any of my books.

An Infectious Disease book on google books said that the function is unknown but may be related to do with the neutrophils need to migrate through tissue, so it could related to making the deformation of the cell possible.

I thought maybe that it could be related to surface area of the nucleus and the associated ER, since neutrophils tend to have large ERs for producing secretory proteins. But that's pure speculation on my part.

The existence of multi-lobed nuclei is something that pops in to my head now and again - but I've never been able to find a satisfactory answer. There really seems to be very little work on the topic (except to note that they exist and can change morphology under certain conditions such as pregnancy and infection).

Both good ideas that you suggest. However, other cell types that move through tissue or are highly active in terms of protein synthesis don't have such odd nuclei.

I was thinking about the myeloblast stem cells that give rise to cells such as the neutrophil, basophil and eosinophil. They often have three nucleoli and neutrophils tend to have a three-lobed nucleus. Sounds horribly like numerology I admit; and doesn't explain their function.

Rapid cell migration through tissues does seem to be something that crops up repeatedly in my searches. Apparently neutrophils can squeeze through some very tight spaces (far tighter than I had imagined), deforming their nuclei as they pass through.

Managed to find one paper (The granulocyte nucleus and lamin B receptor: avoiding the ovoid) that hypothesised that due to the lower levels of lamins A/C and B1 in the nuclear membrane, these cells have highly deformable nuclei. It also mentions some experiments that would appear to show multi-lobed neutrophils moving through Millipore filters more efficiently than those with ovoid nuclei.

Still odd how there are three lobes.

Do these lobes form one interconnected set of DNA, or are each a copy of the other? I was thinking that if they were copies of each other, that it might provide a way to increase physical numbers quickly when it is needed by splitting into individual cells with one nucleus each, since, as far as I know, leukocytes don't undergo cell division outside of their areas of production. Just a wild guess with no real knowledge base to work from.

I believe that it's a single nucleus, just multi lobed. Very cool find Zwirko.

Originally Posted by Zwirko

... deforming their nuclei as they pass through...

I admit I know nothing about this topic, so I'm respectfully asking you to clarify this. Do you mean that the nuclei are originally not lobed and that the squeezing through spaces damages it making it tri-lobal?

Or is it possible that it's an evolutionary adaptation to be able to squeeze through tighter spaces because of the nuclei's tri-lobal form?

The paper I read suggested that their nuclei were easily deformed which could make it easier for them squeeze through tight places as compared to cells having a large spherical nucleus that is more rigid. So they are lobed to begin with and don't take up that odd shape as a result of moving through tissues.

Why there are typically three lobes is not clear - it is even possible that there may be no functional reason at all for three lobes and it is the deformability that is important. Maybe the three lobed structure arises from how the cells develop?