#11392 myelin sheath & Schwann cells

[Chris Mungall]

From Sebastian K. This is causing problems with HPO inference, as we end up with the assumption that myelin is always in the PNS:

[Term]
id: GO:0043209
name: myelin sheath
namespace: cellular_component
def: "An electrically insulating fatty layer that surrounds the axons of many neurons. It is an outgrowth of glial cells: Schwann cells supply the myelin for peripheral neurons while oligodendrocytes supply it to those of the central nervous system." [GOC:jl, NIF_Subcellular:sao-593830697, Wikipedia:Myelin]
synonym: "astrocyte sheath" NARROW [NIF_Subcellular:nlx_subcell_20090204]
synonym: "oligodendrocyte myelin sheath" NARROW [NIF_Subcellular:sao1279474730]
synonym: "Schwann cell myelin sheath" NARROW []
xref: FMA:62983
xref: NIF_Subcellular:sao-593830697
xref: Wikipedia:Myelin
is_a: GO:0044464 ! cell part
***relationship: part_of CL:0000218 ! myelinating Schwann cell

Weaken to 'glial cell'? Introduce two subtypes (oligodend, Schwann)?

To complicate the issue further, some arthropods have 'myelin'; but I think the proposed weakening works for these too.

[Chris Mungall]

Here is the explanation we get - I think it's the GO derived axioms that are at fault

[Doug Howe]

The Schwanns and oligodendrocytes are referred to collectively as "myelinating glial cells" to distinguish them from other types of glia which are non-myelinating. 'Myelin sheath' should be a part of "myelinating glial cell".

Doug

[Chris Mungall]

We have CL:0000328 ! myelin accumulating cell (undefined in CL, inherited from initial version of CL).

This includes 'myelinating Schwann cell', but not oligodendrocyte.

Anyway, I think this class is weird, and should be obsoleted with a consider to CL:new 'myelinating glial cells'

For now, I think we should just generalize the GO axiom to 'glial cell'

CL also makes a distinction between plain Schwann cell and 'myelinating Schwann cell'. Do we need the latter?

         is_a CL:0002573 ! Schwann cell [DEF: "A glial cell that ensheathes axons of neuron in the peripheral nervous system and are necessary for their maintainance and function."]
          is_a CL:0000218 ! myelinating Schwann cell ***  [DEF: "A neuroglial cell of the peripheral nervous system which forms the insulating myelin sheaths of peripheral axons."]

[Chris Mungall]

Also of relevance: https://github.com/obophenotype/uberon/issues/628

[Chris Mungall]

https://code.google.com/p/cell-ontology/issues/detail?id=161

[Paola Roncaglia]

Weakened link: ‘myelin sheath’ part_of ‘glial cell’ rather than ‘myelinating Schwann cell’.
Closing as I see that the other issues are reported in separate trackers.
BTW I love the current parent of CL:0000328 ! myelin accumulating cell... 'stuff accumulating cell' :-)

Thanks,
Paola

[Doug Howe]

Just a quick comment in response to Chris' question above:

"CL also makes a distinction between plain Schwann cell and 'myelinating Schwann cell'. Do we need the latter?"

There are myelinating and non-myelinating Schwann cells and oligodendrocytes. They each derive from a common pool of precursor cells for their specific glial cell..ie Schwann cells derive from a Schwann cell precursor pool and oligodendrocytes from and oligodendrocyte precursor pool.

So for CL, it makes sense to have

Schwann cell
---[i] myelinating Schwann cell
---[i] non-myelinating Schwann cell

Likewise for oligodendrocytes.

Eventually we want
CL: myelinating glial cell (or myelin forming glial cell)
---[P] GO: myelin sheath
---[i] CL: myelinating Schwann cell
---[i] CL: myelinating oligodendrocyte

[Paola Roncaglia]

OK, so setting this ontology ticket to pending, waiting for the CL changes to be done.
Then I will add the link GO myelin sheath part_of CL myelinating glial cell (or myelin forming glial cell). Thanks

Paola

[Paola Roncaglia]

Hi Chris and Doug,

Just following up on this, wondering if the changes in CL have been completed. Otherwise, is there a CL ticket I may refer to?

Thanks,

Paola