TY - JOUR
T1 - Mercury-induced apoptosis and necrosis in murine macrophages
T2 - Role of calcium-induced reactive oxygen species and p38 mitogen-activated protein kinase signaling
AU - Kim, Sang Hyun
AU - Sharma, Raghubir P.
PY - 2004/4/1
Y1 - 2004/4/1
N2 - The current study characterizes the mechanism by which mercury, a toxic metal, induces death in murine macrophages. The cytotoxic EC50 of mercury ranged from 62.7 to 81.1 μM by various assays in J774A.1 cultures; accordingly, we employed 70 μM of mercuric chloride in most experiments. Mercury-induced intracellular calcium modulated reactive oxygen species (ROS) production, which resulted in both cell apoptosis and necrosis indicated by annexin V binding and caspase-3 activity, and propidium-iodide binding. Calcium antagonists abolished ROS production. Mercury stimulated p38 mitogen-activated protein kinase (MAPK) and additively stimulated lipopolysaccharide-activated p38. Mercury-activated p38 was decreased by pretreatment of cells with antioxidants, N-acetylcysteine (NAC) and silymarin, indicating that mercury-induced ROS were involved in p38 activation. Mercury increased the expression of tumor necrosis factor α (TNFα); antioxidants and a specific p38 inhibitor decreased this effect. Pretreatment with antioxidants, p38 inhibitor, and anti-TNFα antibody decreased mercury-induced necrosis; however, anti-TNFα antibody did not decrease mercury-induced apoptosis. Results suggest that mercury-induced macrophage death is a mix of apoptosis and necrosis employing different pathways. P38-mediated caspase activation regulates mercury-induced apoptosis and p38-mediated TNFα regulates necrosis in these cells. Calcium regulates ROS production and mercury-induced ROS modulate downstream p38 that regulates both apoptosis and necrosis.
AB - The current study characterizes the mechanism by which mercury, a toxic metal, induces death in murine macrophages. The cytotoxic EC50 of mercury ranged from 62.7 to 81.1 μM by various assays in J774A.1 cultures; accordingly, we employed 70 μM of mercuric chloride in most experiments. Mercury-induced intracellular calcium modulated reactive oxygen species (ROS) production, which resulted in both cell apoptosis and necrosis indicated by annexin V binding and caspase-3 activity, and propidium-iodide binding. Calcium antagonists abolished ROS production. Mercury stimulated p38 mitogen-activated protein kinase (MAPK) and additively stimulated lipopolysaccharide-activated p38. Mercury-activated p38 was decreased by pretreatment of cells with antioxidants, N-acetylcysteine (NAC) and silymarin, indicating that mercury-induced ROS were involved in p38 activation. Mercury increased the expression of tumor necrosis factor α (TNFα); antioxidants and a specific p38 inhibitor decreased this effect. Pretreatment with antioxidants, p38 inhibitor, and anti-TNFα antibody decreased mercury-induced necrosis; however, anti-TNFα antibody did not decrease mercury-induced apoptosis. Results suggest that mercury-induced macrophage death is a mix of apoptosis and necrosis employing different pathways. P38-mediated caspase activation regulates mercury-induced apoptosis and p38-mediated TNFα regulates necrosis in these cells. Calcium regulates ROS production and mercury-induced ROS modulate downstream p38 that regulates both apoptosis and necrosis.
KW - 5-chloromethyl-2′,7′-dichlorodihydro-fluorescein diacetate
KW - Calcium
KW - Caspase 3
KW - CM-HDCFDA
KW - DHR
KW - Dihydrorhodamine
KW - ERK
KW - Mercury
KW - Mitogen-activated protein kinases
KW - Reactive oxygen species
KW - Tumor necrosis factor α
UR - http://www.scopus.com/inward/record.url?scp=1642400099&partnerID=8YFLogxK
U2 - 10.1016/j.taap.2003.11.020
DO - 10.1016/j.taap.2003.11.020
M3 - Article
C2 - 15050407
AN - SCOPUS:1642400099
SN - 0041-008X
VL - 196
SP - 47
EP - 57
JO - Toxicology and Applied Pharmacology
JF - Toxicology and Applied Pharmacology
IS - 1
ER -