Table 1.
Expression of phagocytosis-related receptors by microglia.
| Phagocyte receptor | Gene | Function | Brain database (68) | Immunological database (skyline) | Human database (69) | DAM microglia (47) | Aging human signature (70) | Aging human database (70) vs. (68) | Cerebellum vs. Striatum (71) | PAM microglia (48) |
|---|---|---|---|---|---|---|---|---|---|---|
| G2A | GPR132 | G protein-coupled receptor (GPCR), recognizes lysophosphatidylcholine | Microglia | T lymphocytes, DCs. Neurotrophils | Mo > Mi =Ma | - | HuMi_Aged | Up | - | - |
| CX3CR1 | CX3CR1 | Fractalkine receptor | Microglia | Microglia (Monocytes low) | Mi >> Mo >> Ma | Down | HuMi_Aged | Down | Striatal | Down |
| P2Y6 | P2RY6 | Purinergic receptor type Y6 | Microglia | Microglia (Macrophages low) | Mi = Ma > Mo | Down | HuMi_Aged | Up | Striatal=Cerebellar | = |
| P2Y12 | P2RY12 | Purinergic receptor type Y12 | Microglia (OPCs low) | Microglia | Mi >> Mo >> Ma | Down | HuMi_Aged | Down | Striatal | Down |
| BAI1 | BAI1 (ADGRB) | adhesion G protein-coupled receptor B1 | Astrocytes, neurons, OPCs, oligodendrocytes | Epithelial cells, neutrophils, NKs | Mi = Ma = Mo | - | - | - | - | - |
| TIM4 | TIMD4 | T cell immunoglobulin and mucin domain containing 4 | Microglia | Macrophages | - | - | - | - | Cerebellar | - |
| Stabilin 1 | STAB1 | - | Microglia (endothelium low) | Microglia, endothelium | Mi = Ma > Mo | Down | HuMi_Aged | Up | - | Up |
| Stabilin 2 | STAB2 | - | Endothelium | Endothelium, macrophages | - | - | - | - | - | - |
| SIRPa | SIRPA | Signal regulatory protein alpha | Microglia | Microglia, macrophages, neutrophils | Mi = Ma = Mo | Down | - | Down | Striatal | - |
| CD300b | CD300LB | CD300 molecule like family member B | Microglia | Neurotrophils, macrophages | Mo = Ma >> Mi | - | - | - | - | - |
| TREM2 | TREM2 | Triggering receptor expressed on myeloid cells 2 | Microglia | Microglia | Mi > Ma > Mo | Up | HuMi_Aged | Up | - | Up |
| MerTK | MERTK | MER proto-oncogene, tyrosine kinase | Astrocytes, microglia | Microglia, macrophages | Mi >Ma > Mo | Down | - | Down | Striatal | - |
| Axl | AXL | AXL receptor tyrosine kinase | Astrocytes, OPCs | Macrophages | Mi > Mo > Ma | Up | HuMi_Aged | No change | Cerebellar | - |
| Tyro3 | TYRO3 | TYRO3 protein tyrosine kinase | Oligodendrocytes | NKs, T lymphocytes | Mi = Ma = Mo | - | - | - | - | - |
| CD36 | CD36 | Fatty acid translocase | Astrocytes, OPCs, microglia | macrophages, endothelium | Ma = Mo >> Mi | - | - | - | - | - |
| CD11b | ITGAM | Integrin subunit alpha M | Microglia | Neurotrophils, macrophages, microglia | Mi = Ma = Mo | Down | HuMi_Aged | No change | Striatal | - |
| CD206 | MRC1 | Mannose receptor C-Type 1 | Microglia | Macrophages | Ma > Mi > Mo | - | HuMi_Aged | Down | Cerebellar | - |
| Clec7a | CLEC7A | C-type lectin domain containing 7A | Microglia | Macrophages, neutrophils, monocytes | Mo > Ma > Mi | Up | HuMi_Aged | Down | - | Up |
| CD22 | CD22 | Sialic acid-binding Ig-like lectin 2 | Microglia | Macrophages | Ma > Mo > Mi | Up | - | No change | Striatal | - |
The table indicates the name of the receptor, the gene ID, its function and the expression in different cell types found in RNAseq public databases: a brain-specific database of microglia compared to other brain cells (68); an immunological database of microglia and other immune cells (http://rstats.immgen.org/Skyline/skyline.html); a human database of microglia (Mi), macrophages (Ma), and monocytes (Mo) (69); a database of genes upregulated (Up) and downregulated (Down) in disease-associated microglia (DAM) (47); a database of genes specific of a human aging signature (HuMi-aged) (70); a database of genes enriched in cerebellar (non-phagocytic) and striatal (phagocytic) microglia (71); and a database of genes upregulated (Up) or downregulated (Down) proliferative-region associated microglia (PAM)(48).