Stargate-X

The package is a python implementation of a bipartite directed multigraph extracted from the Reactome database. Its underlying implementation uses networkx.

The graph represents reactions and physical entities as nodes. Edges are instead classified into 5 categories:

• input
• output
• catalyst
• positiveRegulator
• negativeRegulator

The package provides a wrapper for the networkx.MultiDiGraph class: the ReactomeGraph. Each graph instance is associated with a certain species and can either be:

• loaded from pre-built binaries shipped alongside the package
• built directly from a Neo4j instance running on the user’s machine

NOTE: the user may prefer the latter option in order to control which specific version of Reactome’s database is used to generate the graphs. The latest supported version for this package will be periodically updated.

When building from a Neo4j instance, the package extracts data from the Reactome graph database.

Installation

git clone https://github.com/marinoandrea/stargate-x.git
cd stargate-x
pip install .

Usage

In order to use the pre-built graphs, just call the load method passing the species as an argument:

from stargate_x import ReactomeGraph, Species

hsa_graph = ReactomeGraph.load('Homo sapiens')
# or
hsa_graph = ReactomeGraph.load(Species.HSA)

In order to build a graph directly from Reactome's database, an active Neo4j instance is required. The connection URI can be specified in the options (it defaults to bolt://localhost:7687):

from stargate_x import ReactomeGraph, Species

hsa_graph = ReactomeGraph.build('Homo sapiens', options={'neo4j_uri': 'bolt://<YOUR_HOST>:<YOUR_PORT>'})
# or
hsa_graph = ReactomeGraph.build(Species.HSA, options={'neo4j_uri': 'bolt://<YOUR_HOST>:<YOUR_PORT>'})

API Reference

ReactomeGraph

Represents a graph for a certain species.

PROPERTY	TYPE	DESCRIPTION
event_nodes	Set[str]	Set containing all the event nodes identifiers.
entity_nodes	Set[str]	Set containing all the entity nodes identifiers.
compartments	Iterable[Compartment]	List of all cellular compartments for this graph instance.
pathways	Iterable[Pathway]	List of all pathways for this graph instance.
top_level_pathways	Iterable[Pathway]	List of all top level pathways for this graph instance.

---

METHOD	ARGUMENTS	RETURNS	DESCRIPTION
get_pathway_subgraph	pathway: str - pathway identifier	ReactomeGraph	Generate subgraph using nodes from the given pathway.
get_compartment_subgraph	compartment: str - compartment GO identifier (eg: GO:0005886)	ReactomeGraph	Generate subgraph using nodes from the given compartment.
load	species: Union[Species, str] - species name or enumeration	ReactomeGraph	Factory method, builds a Reactome graph from a pickled python object.
build	species: Union[Species, str] - species name or enumeration	ReactomeGraph	Factory method, builds a Reactome graph. Requires a working Neo4j instance containing Reactome data.

Species

Enumeration with valid Reactome species (source).

Pathway

Dataclass containing basic pathway information.

PROPERTY	TYPE	DESCRIPTION
id	str	Reactome pathway identifier.
name	str	Reactome display name.
is_top_level	bool	Whether the pathway is a top level pathway.
in_disease	bool	Whether the pathway is part of a disease.

Compartment

Dataclass containing basic cellulare compartment information.

PROPERTY	TYPE	DESCRIPTION
id	str	GO compartment identifier (starting with 'GO:').
name	str	Reactome display name.

Examples

Obtain a subgraph relative to a specific pathway:

from stargate_x import ReactomeGraph

hsa_graph = ReactomeGraph.load('Homo sapiens')
signal_transduction_subgraph = hsa_graph.get_pathway_subgraph('R-HSA-162582')

or to a specific cellular compartment:

from stargate_x import ReactomeGraph

hsa_graph = ReactomeGraph.load('Homo sapiens')
plasma_membrane_subgraph = hsa_graph.get_compartment_subgraph('GO:0005886')

Here is an example where we obtain centrality measures for all nodes in a specific pathway:

import networkx as nx

import stargate_x as sx

signal_transduction_subgraph = sx.ReactomeGraph\
    .load("Homo sapiens")
    .get_pathway_subgraph("R-HSA-162582")

# calculate different centrality measures for every node in the subgraph
lapl = sx.laplacian_centrality(signal_transduction_subgraph, deg_type="out_degree")
hidx = sx.h_index_centrality(signal_transduction_subgraph, deg_type="out_degree")
levr = sx.leverage_centrality(signal_transduction_subgraph, deg_type="out_degree")

Here is an example where we analyze the connectivity features of a single node in a specific compartment and pathway:

import networkx as nx

import stargate_x as sx

# select the cytosol compartment subgraph in the nucleotides metabolism pathway
cytosol_nucleotides_metabolism_subgraph = sx.ReactomeGraph\
    .load("Homo sapiens")\
    .get_pathway_subgraph("R-HSA-15869")\
    .get_compartment_subgraph("GO:0005829")

# find all nodes reachable from ATP using standard networkx functionalities
reachable_nodes_from_atp = nx.descendants(cytosol_nucleotides_metabolism_subgraph, "R-ALL-113592")

Here is an example of how to obtain participating compounds given a reaction node:

import stargate_x as sx

signal_transduction_graph = sx.ReactomeGraph\
    .load("Homo sapiens")
    .get_pathway_subgraph("R-HSA-9709957")

# find all compounds participating in the Phosphorylation of complexed TSC2 by PKB
# within the Signal Transduction top-level pathway
compounds = signal_transduction_graph.neighbors("R-HSA-165182")

Authors

• Andrea Marino - (marinoandrea)

See also the list of contributors who participated in this project.