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Stimulation of Mitochondrial Fragmentation and Mitophagy by TNFα in Microvascular Endothelial Cells
Author(s) -
Kalogeris Theodore,
Korthuis Ronald
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.723.9
Subject(s) - mitophagy , microbiology and biotechnology , mitochondrion , mitochondrial biogenesis , parkin , mitochondrial fission , mitochondrial ros , biology , fragmentation (computing) , cytokine , tumor necrosis factor alpha , chemistry , apoptosis , immunology , autophagy , biochemistry , medicine , ecology , disease , parkinson's disease
The inflammatory cytokine, TNFα, decreases mitochondrial mass in cultured microvascular endothelial cells. We previously showed that this effect might be explained by an inhibitory effect of TNFα on eNOS‐dependent expression of PGC‐1α. However, other investigators have reported that TNFα stimulates mitophagy, and a possible mitophagic effect of TNFα was not ruled out in our own studies. In order to more fully understand how TNFα affects endothelial mitochondrial function, we have begun to examine the effect of this cytokine on measures of mitochondrial network integrity and mitophagy in human dermal microvascular endothelial cells (HMEC‐1). Since fragmentation of mitochondrial networks via mitochondrial fission has been shown to be necessary for subsequent mitophagy, we examined the time‐dependent effect of TNFα on mitochondrial network integrity using fluorescence microscopy of cells loaded with the mitochondrial‐specific dye, mitotracker green (MTG). Compared with control cells, TNF treatment increased mitochondrial fragmentation by 12% and 20% at 24 and 48 h, respectively. This was associated with a similar time‐dependent increase in mitochondrial PINK‐1, and recruitment of both drp‐1 and parkin, suggesting increases in both mitochondrial fission and mitophagy progression. We also observed an increase in the cellular ratio of LC3II/LC3I, a marker of autophagasome formation. Finally, TNFα‐induced decrease in mitochondrial mass was significantly attenuated in cells co‐incubated with mitophagy inhibitors, 3‐methyladenine or m‐divi. Taken together with our previous results, these findings suggest that TNFα may exert negative effects on endothelial mitochondrial capacity by simultaneously blocking organellar biogenesis and stimulating mitophagic destruction. Support or Funding Information Supported by AA014945 & HL095486.