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Gene regulation in activated microglia by adenosine A3 receptor agonists: a transcriptomics study
Alejandro Lillo1,2, Joan Serrano-Marín3, Jaume Lillo1,3
1Department of Biochemistry and Physiology, School of Pharmacy and Food Science, Universitat de Barcelona, Barcelona, Spain.
Abstract:
Most neurodegenerative disorders, including the two most common, Alzheimer's disease (AD) and Parkinson's disease (AD), course with activation of microglia, the resident innate immune cells of the central nervous system. A3 adenosine receptor (A3R) agonists have been proposed to be neuroprotective by regulating the phenotype of activated microglia. RNAseq was performed using samples isolated from lipopolysaccharide/interferon-γ activated microglia treated with 2-Cl-IB-MECA, a selective A3R agonist. The results showed that the number of negatively regulated genes in the presence of 2-Cl-IB-MECA was greater than the number of positively regulated genes. Gene ontology enrichment analysis showed regulation of genes participating in several cell processes, including those involved in immune-related events. Analysis of known and predicted protein-protein interactions showed that Smad3 and Sp1 are transcription factors whose genes are regulated by A3R activation. Under the conditions of cell activation and agonist treatment regimen, 2-Cl-IB-MECA did not lead to any tendency to favor the expression of genes related to neuroprotective microglia (M2).
Insights
A3 adenosine receptor (A3R) agonists regulate microglia, the brain's immune cells, in neurodegenerative diseases. This study found that a specific A3R agonist primarily down-regulated genes, without promoting neuroprotective microglia phenotypes.
Area of Science:
- Neuroscience
- Immunology
- Pharmacology
Background:
- Neurodegenerative diseases like Alzheimer and Parkinson involve microglial activation.
- A3 adenosine receptor (A3R) agonists are investigated for potential neuroprotection by modulating microglial phenotypes.
Purpose of the Study:
- To investigate the effect of a selective A3R agonist (2-Cl-IB-MECA) on gene expression in activated microglia.
- To determine if A3R activation promotes a neuroprotective microglial phenotype (M2).
Main Methods:
- RNA sequencing of microglia activated by lipopolysaccharide/interferon-γ and treated with 2-Cl-IB-MECA.
- Gene ontology enrichment analysis to identify regulated cellular processes.
- Protein-protein interaction analysis to identify key transcription factors.
Main Results:
- More genes were negatively regulated than positively regulated by 2-Cl-IB-MECA.
- Gene ontology analysis revealed regulation of immune-related and other cellular processes.
- Smad3 and Sp1 were identified as transcription factors regulated by A3R activation.
- The A3R agonist did not favor the expression of genes associated with M2 neuroprotective microglia.
Conclusions:
- A3R activation in microglia leads to broad gene expression changes, with a predominant down-regulation.
- The tested A3R agonist does not induce a classical M2 neuroprotective microglial phenotype under these experimental conditions.
- Further research is needed to elucidate the precise role of A3R modulation in neuroinflammation and neurodegeneration.
