TY - JOUR
T1 - Pathophysiological roles of extracellular nucleotides in glial cells
T2 - Differential expression of purinergic receptors in resting and activated microglia
AU - Bianco, Fabio
AU - Fumagalli, Marta
AU - Pravettoni, Elena
AU - D'Ambrosi, Nadia
AU - Volonte, Cinzia
AU - Matteoli, Michela
AU - Abbracchio, Maria P.
AU - Verderio, Claudia
PY - 2005/4
Y1 - 2005/4
N2 - Microglial cells are the major cellular elements with immune function inside the CNS and play important roles in orchestrating inflammatory brain response to hypoxia and trauma. Although a complete knowledge of the endogenous factors leading to a prompt activation of microglia is not yet available, activation of P2 purinoreceptors by extracellular ATP has been indicated as a primary factor in microglial response. A still unresolved question, however, is which subtype(s) of P2 receptors mediate(s) the response to ATP. By a combination of RT-PCR, Western blotting, and single-cell calcium imaging, we assessed the presence and the activity of P2 receptor subtypes in the mouse microglial cell line N9. All members of the P2 receptor family, including the recently reported receptor for sugar nucleotides (P2Y14), were found to be present in these cells at mRNA and/or protein level. The functionality of the receptors was assessed by analysis of the calcium responses evoked by specific agonists both in N9 cells and in primary microglia from rat brain. Interestingly, a different functional profile of P2 receptors was observed in resting or in LPS-activated N9 cells. Overnight exposure to LPS increased P2Y6 and P2Y14, decreased P2X7, and left unchanged P2Y1 and P2Y2,4 receptor activity. The change in the P2 receptor profile in activated cells suggests selective roles for specific P2 receptor subtypes in microglial activation triggered by LPS. We speculate that modulation of microglial cell function via subtype-selective P2 receptor ligands may open up new strategies in the therapeutic management of inflammatory neurological diseases characterized by abnormal microglia response.
AB - Microglial cells are the major cellular elements with immune function inside the CNS and play important roles in orchestrating inflammatory brain response to hypoxia and trauma. Although a complete knowledge of the endogenous factors leading to a prompt activation of microglia is not yet available, activation of P2 purinoreceptors by extracellular ATP has been indicated as a primary factor in microglial response. A still unresolved question, however, is which subtype(s) of P2 receptors mediate(s) the response to ATP. By a combination of RT-PCR, Western blotting, and single-cell calcium imaging, we assessed the presence and the activity of P2 receptor subtypes in the mouse microglial cell line N9. All members of the P2 receptor family, including the recently reported receptor for sugar nucleotides (P2Y14), were found to be present in these cells at mRNA and/or protein level. The functionality of the receptors was assessed by analysis of the calcium responses evoked by specific agonists both in N9 cells and in primary microglia from rat brain. Interestingly, a different functional profile of P2 receptors was observed in resting or in LPS-activated N9 cells. Overnight exposure to LPS increased P2Y6 and P2Y14, decreased P2X7, and left unchanged P2Y1 and P2Y2,4 receptor activity. The change in the P2 receptor profile in activated cells suggests selective roles for specific P2 receptor subtypes in microglial activation triggered by LPS. We speculate that modulation of microglial cell function via subtype-selective P2 receptor ligands may open up new strategies in the therapeutic management of inflammatory neurological diseases characterized by abnormal microglia response.
KW - Adenine and uridine nucleotides
KW - Calcium signaling
KW - LPS activation
KW - Microglia
KW - P2X and P2Y receptors
KW - UDP-glucose
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U2 - 10.1016/j.brainresrev.2004.12.004
DO - 10.1016/j.brainresrev.2004.12.004
M3 - Article
C2 - 15850653
AN - SCOPUS:17844385044
VL - 48
SP - 144
EP - 156
JO - Brain Research Reviews
JF - Brain Research Reviews
SN - 0165-0173
IS - 2
ER -