The physiologic aggresome mediates cellular inactivation of iNOS.
Nitric Oxide (NO), produced by inducible nitric oxide synthase (iNOS), has been implicated in the pathogenesis of various biological and inflammatory disorders. Recent evidence suggests that aggresome formation is a physiologic stress response not limited to misfolded proteins. That stress response, termed "physiologic aggresome," is exemplified by aggresome formation of iNOS, an important host defense protein. The functional significance of cellular formation of the iNOS aggresome is hitherto unknown. In this study, we used live cell imaging, fluorescence microscopy, and intracellular fluorescence NO probes to map the subcellular location of iNOS and NO under various conditions. We found that NO production colocalized with cytosolic iNOS but aggresomes containing iNOS were distinctly devoid of NO production. Further, cells expressing iNOS aggresomes produced significantly less NO as compared with cells not expressing aggresomes. Importantly, primary normal human bronchial epithelial cells, stimulated by cytokines to express iNOS, progressively sequestered iNOS to the aggresome, a process that correlated with marked reduction of NO production. These results suggest that bronchial epithelial cells used the physiologic aggresome mechanism for iNOS inactivation. Our studies reveal a novel cellular strategy to terminate NO production via formation of the iNOS aggresome.
Pandit
Lavannya
L
Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
Kolodziejska
Katarzyna E
KE
Zeng
Shenyan
S
Eissa
N Tony
NT
D001980:Bronchi / Q000166:cytology / Q000201:enzymology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D002479:Inclusion Bodies / Q000187:drug effects / Q000201:enzymology*; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D012235:Rhodamines / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology
D016207:Cytokines; D012235:Rhodamines; C532273:diaminorhodamine-4M acetoxymethyl ester; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II