#11481 either child term or synonym request for GO:0000266 mitochondrial fission

[Paul Denny]

Based on these papers,
PMID: 19279012
PMID:11038192

I think that "mitochondrial fragmentation" is an exact synonym of:

GO:0000266 mitochondrial fission

Please check and if in agreement, add to definition.

GOC:PARL
GOC:pad

[Valerie Wood]

Hi PAul,

I think these are different. Mitochondrial fission is related to the processes of mitochondrial biogenesis and inheritance when mitochondrial are divided and partitioned in a normal cell in a regulated way (performed by dynamin GTPases)

As far as I'm aware mitochondrial fragmentation is an output of autophagy? I don't think the 2 processes are related.

it seems as though fragmentation, if it belongs in GO it would belong under something like this:
GO:0006921 cellular component disassembly involved in execution phase of apoptosis

val

[David Hill]

Hi Val and Paul,

We already have 'mitochondrial fragmentation involved in apoptosis' and as you point out Val, it is an incorrect child of mitochondrial fission. I propose that we move the fragmentation term to where Val suggests. Agreed?

-David

[Paul Denny]

Thanks Val, David.
Agreed about GO:0043653 mitochondrial fragmentation involved in apoptotic process,
but in PMID:19279012 they state:
"We found that stable knockdown of PINK1 induced mitochondrial fragmentation and autophagy in SH-SY5Y [human neuroblastoma] cells" - they don't mention apoptosis as an outcome.
Does this mean that we need a new, more general parent term to
GO:0043653 mitochondrial fragmentation involved in apoptotic process
e.g. simply GO:ID# mitochondrial fragmentation ?

[David Hill]

Maybe 'mitochondrial fragmentation involved in autophagy'? Do they share similar mechanisms? Val?

[Valerie Wood]

I don't know much about them.... maybe the people who edited apoptosis can help

[David Hill]

I propose we make two new terms: 'mitochondrial disassembly' and 'mitochondrial fragmentation involved in autophagy (mitophagy??)'. The latter term would be a part_of 'mitochondrion degradation' and the existing 'mitochondrial fragmentation involved in apoptotic process' would be moved to be an is_a child of mitochondrial disassembly. What do you think?

[Valerie Wood]

I don't understand the difference between disassembly and degradation. How do you distinguish?

[David Hill]

Sorry. I meant to say (somewhere I lost a huge bit of my thoughts):

I propose we make two new terms: 'mitochondrial disassembly' and 'mitochondrial fragmentation involved in autophagy (mitophagy??)'. The latter term would be a part_of 'autophagy (mitophagy?)' and an is_a 'mitochondrial disassembly'. The existing 'mitochondrial fragmentation involved in apoptotic process' would be moved to be an is_a child of mitochondrial disassembly. What do you think?

[Valerie Wood]

yep sounds good

[Paul Denny]

Dear David, Val,
thanks very much for your help - these sound good to me.
Paul

[David Hill]

Actually this is not as straightforward as it sounds. 'mitochondrion degradation' already has an exact synonym of mitophagy and is defined as "The autophagic process in which mitochondria are delivered to the vacuole and degraded in response to changing cellular conditions.'

Looking at PMID:19279012 it looks like the loss of PINK1 leads to defects in the regulation of mitochondrial fission and mitophagy (autophagy). I think the fragmentation is the result of errors in these processes and is pathological. See the last paragraph of the paper and let me know if you agree.

PMID:11038192 also describes the fragmentation as being a pathological result of the balance of fission and fusion being disrupted.

In light of this, I think the terms that you really want for annotation may be 'regulation of mitochondrial fission' and 'regulation of mitochondrion degradation'. I still agree that the apoptotic term might be better housed under organelle diassembly rather than fission.