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.
Here is the explanation we get - I think it's the GO derived axioms that are at fault
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
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?
Also of relevance: https://github.com/obophenotype/uberon/issues/628
https://code.google.com/p/cell-ontology/issues/detail?id=161
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
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
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
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