The adenosine generating enzymes CD39/CD73 control microglial processes ramification in the mouse brain

• Published in: PloS one Vol. 12; no. 4; p. e0175012
• Main Authors: Matyash, Marina, Zabiegalov, Oleksandr, Wendt, Stefan, Matyash, Vitali, Kettenmann, Helmut
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 04.04.2017; Public Library of Science (PLoS)
• Subjects: 5'-Nucleotidase; 5'-Nucleotidase - deficiency; 5'-Nucleotidase - genetics; 5'-Nucleotidase - metabolism; Adenosine; Adenosine - metabolism; Adenosine - pharmacology; Adenosine diphosphate; Adenosine Triphosphate - metabolism; Animal euthanasia; Animals; Animals, Newborn; Antigens, CD - genetics; Antigens, CD - metabolism; Apyrase; Apyrase - deficiency; Apyrase - genetics; Apyrase - metabolism; ATP; Balancing; Biology and Life Sciences; Brain; Brain - cytology; Brain - growth & development; Brain - metabolism; Brain Injuries - drug therapy; Brain Injuries - metabolism; Brain Injuries - pathology; Brain slice preparation; CD39 antigen; CD73 antigen; Cell Count; Cells, Cultured; Chemotaxis; Clonal deletion; Data processing; Degradation; Dipyridamole; Dipyridamole - pharmacology; Disease Models, Animal; Dosage and administration; Elongation; Engineering and Technology; Enzymes; Equilibrative Nucleoside Transporter 1 - metabolism; Genetic transformation; Health aspects; In vitro methods and tests; Inhibition; Medicine; Metabolic Networks and Pathways; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Microglia; Microglia - cytology; Microglia - metabolism; Microglial cells; Motility; Neurosciences; Neutrophils; Nucleoside transporter; Nucleotidase; Phenotype; Physiological aspects; Receptors; Receptors, Purinergic P2Y12 - metabolism; Research and Analysis Methods; Rodents; Slicing; Transformation; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0175012

Microglial cells invade the brain as amoeboid precursors and acquire a highly ramified morphology in the postnatal brain. Microglia express all essential purinergic elements such as receptors, nucleoside transporters and ecto-enzymes, including CD39 (NTPDase1) and CD73 (5'-nucleotidase), which sequentially degrade extracellular ATP to adenosine. Here, we show that constitutive deletion of CD39 and CD73 or both caused an inhibition of the microglia ramified phenotype in the brain with a reduction in the length of processes, branching frequency and number of intersections with Sholl spheres. In vitro, unlike wild-type microglia, cd39-/- and cd73-/- microglial cells were less complex and did not respond to ATP with the transformation into a more ramified phenotype. In acute brain slices, wild-type microglia retracted approximately 50% of their processes within 15 min after slicing of the brain, and this phenomenon was augmented in cd39-/- mice; moreover, the elongation of microglial processes towards the source of ATP or towards a laser lesion was observed only in wild-type but not in cd39-/- microglia. An elevation of extracellular adenosine 1) by the inhibition of adenosine transport with dipyridamole, 2) by application of exogenous adenosine or 3) by degradation of endogenous ATP/ADP with apyrase enhanced spontaneous and ATP-induced ramification of cd39-/- microglia in acute brain slices and facilitated the transformation of cd39-/- and cd73-/- microglia into a ramified process-bearing phenotype in vitro. These data indicate that under normal physiological conditions, CD39 and CD73 nucleotidases together with equilibrative nucleoside transporter 1 (ENT1) control the fate of extracellular adenosine and thereby the ramification of microglial processes.