Loss of manganese superoxide dismutase leads to abnormal growth and signal transduction in mouse embryonic fibroblasts.
Manganese superoxide dismutase (MnSOD) in the mitochondria plays an important role in cellular defense against oxidative damage. Homozygous MnSOD knockout (Sod2(-/-)) mice are neonatal lethal, indicating the essential role of MnSOD in early development. To investigate the potential cellular abnormalities underlying the aborted development of Sod2(-/-) mice, we examined the growth of isolated mouse embryonic fibroblasts (MEFs) from Sod2(-/-) mice. We found that the proliferation of Sod2(-/-) MEFs was significantly decreased compared with wild-type MEFs despite the absence of morphological differences. The Sod2(-/-) MEFs produced less cellular ATP, had lower O(2) consumption, generated more superoxide, and expressed less Prdx3 protein. Furthermore, the loss of MnSOD dramatically altered several markers involved in cell proliferation and growth, including decreased growth stimulatory function of mTOR signaling and enhanced growth inhibitory function of GSK-3β signaling. Interestingly, the G-protein-coupled receptor-mediated intracellular Ca(2+) signal transduction was also severely suppressed in Sod2(-/-) MEFs. Finally, the ratio of microtubule-associated protein light chain 3 (LC3)-II/LC3-I, an index of autophagic activity, was increased in Sod2(-/-) MEFs, consistent with a reduction in mTOR signal transduction. These data demonstrate that MnSOD deficiency results in alterations in several key signaling pathways, which may contribute to the lethal phenotype of Sod2(-/-) mice.
Zhang
Yiqiang
Y
Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
Zhang
Hong-Mei
HM
Shi
Yun
Y
Lustgarten
Michael
M
Li
Yan
Y
Qi
Wenbo
W
Zhang
Bin-Xian
BX
Van Remmen
Holly
H
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000235:genetics; D049109:Cell Proliferation; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006131:Growth Inhibitors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D018384:Oxidative Stress / Q000235:genetics; D010101:Oxygen Consumption / Q000235:genetics; D061105:Peroxiredoxin III; D054464:Peroxiredoxins / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D000099156:Superoxide Dismutase 2
D000255:Adenosine Triphosphate; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D006131:Growth Inhibitors; D061105:Peroxiredoxin III; D054464:Peroxiredoxins; D013482:Superoxide Dismutase; D013481:Superoxides; D058570:TOR Serine-Threonine Kinases; D000099156:Superoxide Dismutase 2; C516116:Prdx3 protein, mouse; C546843:mTOR protein, mouse; C000605507:Gsk3b protein, mouse