Grounding of micro-RNAs

[bgyori]

We actually get a pretty good amount of micro-RNAs from BioPAX and reading. The reading systems pick them up as named entities but don't have the resources to ground them. BioPAX grounds micro-RNAs to "mirtarbase", e.g. hsa-miR-26b-5p is grounded to "MIRT006307". This is an interaction database, not a micro-RNA database (like miRBase) and so we would probably need to map these IDs. So we could:

• introduce a new db_refs entry key for micro-RNAs, probably miRBase
• map mirtarbase BioPAX grounding to miRBase db_refs
• integrate micro-RNA resources into reading systems or grounding-map them ourselves

[cthoyt]

Heads up to Sumit (@maestroe) since this is relevant to our discussion for next week

[cthoyt]

@lingling93 did a lot of work parsing miRBase in https://github.com/bio2bel/mirbase. Specifically, downloading the terminology (which includes names, identifiers, synonyms, and xrefs) can be found at https://github.com/bio2bel/mirbase/blob/master/src/bio2bel_mirbase/parser.py

There's something else at https://github.com/bio2bel/mirtarbase that also gets all of the data from miRTarBase, but not as nicely in a JSON object as this

[cthoyt]

After the last two PR's get reviewed, we might consider calling this done :)