Mitochondrial biogenesis contributes to ischemic neuroprotection afforded by LPS pre-conditioning.
Although alterations in mitochondrial dynamics are associated with cellular responses to injury, the functional role of these dynamic changes in ischemic neurons is underexplored. One of these dynamic responses to injury includes mitochondrial biogenesis. Various sublethal pre-conditioning stimuli that induce an ischemic-tolerant state [e.g., lipopolysaccharide (LPS)] may also induce mitochondrial biogenesis. Using neuron-enriched cultures, we found that sublethal LPS pre-conditioning induced both ischemic tolerance and markers of mitochondrial biogenesis with overlapping dose-response temporal kinetics. Sublethal LPS transiently increased the expression of critical components of the mitochondrial transcriptional machinery, including nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM), as well as mtDNA copy number, mitochondrial protein levels, and markers of functional mitochondria, such as increased cellular ATP content, citrate synthase activity, and maximal respiration capacity. Importantly, knockdown of TFAM abrogated both the induction of mitochondrial biogenesis and the neuroprotective pre-conditioning effects of LPS. Several signaling pathways coordinated these events. AMPK inhibition suppressed NRF1 and TFAM expression by LPS, whereas PI3K/Akt signaling was necessary for the nuclear translocation of NRF1 and subsequent induction of TFAM. This is the first demonstration that LPS pre-conditioning initiates multiple signaling pathways leading to mitochondrial biogenesis in neurons and that these dynamic changes contribute to ischemic tolerance.
State Key Laboratory of Medical Neurobiology and Institute of Brain Sciences, Shanghai, China.
R Anne
RA
Stetler
Rehana K
RK
Leak
Wei
W
Yin
Lili
L
Zhang
Suping
S
Wang
Yanqin
Y
Gao
Jun
J
Chen
D000091162:AMP-Activated Protein Kinase Kinases; D000255:Adenosine Triphosphate / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004334:Drug Administration Schedule; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D005822:Genetic Vectors / Q000235:genetics; D005947:Glucose / Q000172:deficiency / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism / Q000517:prevention & control; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D063269:Mitochondrial Turnover / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure; D018696:Neuroprotective Agents / Q000008:administration & dosage*; D051266:Nuclear Respiratory Factor 1 / Q000235:genetics / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000235:genetics / Q000378:metabolism; D015388:Organelles / Q000187:drug effects / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D024101:Mitochondrial Proteins; D018696:Neuroprotective Agents; D051266:Nuclear Respiratory Factor 1; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D011720:Pyrazoles; D011743:Pyrimidines; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C422562:mitochondrial transcription factor A; C516138:dorsomorphin; D000255:Adenosine Triphosphate; D002950:Citrate (si)-Synthase; D011494:Protein Kinases; D051058:Oncogene Protein v-akt; D000091162:AMP-Activated Protein Kinase Kinases; D005947:Glucose