Disruption of astrocyte STAT3 signaling decreases mitochondrial function and increases oxidative stress in vitro.
BACKGROUND
Astrocytes exert a wide variety of functions in health and disease and respond to a wide range of signaling pathways, including members of the Janus-kinase signal transducers and activators of transcription (Jak-STAT) family. We have recently shown that STAT3 is an important regulator of astrocyte reactivity after spinal cord injury in vivo[1].


RESULTS
Here, we used both a conditional gene deletion strategy that targets the deletion of STAT3 selectively to astrocytes (STAT3-CKO), and a pharmacological inhibitor of JAK-2, AG490, in cultured astrocytes in vitro, to investigate potential functions and molecules influenced by STAT3 signaling in relation to mitochondrial function and oxidative stress. Our findings show that the absence of STAT3 signaling in astrocytes leads to (i) increased production of superoxide anion and other reactive oxygen species and decreased level of glutathione, (ii) decreased mitochondrial membrane potential and decreased ATP production, and (iii) decreased rate of cell proliferation. Many of the differences observed in STAT3-CKO astrocytes were distinctly altered by exposure to rotenone, suggesting a role for complex I of the mitochondrial electron transport chain. Gene expression microarray studies identified numerous changes in STAT3-CKO cells that may have contributed to the identified deficits in cell function.


CONCLUSIONS
Taken together, these STAT3-dependent alterations in cell function and gene expression have relevance to both reactive gliosis and to the support and protection of surrounding cells in neural tissue.
Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America. tsarafian@mednet.ucla.edu
Theodore A
TA
Sarafian
Cindy
C
Montes
Tetsuya
T
Imura
Jingwei
J
Qi
Giovanni
G
Coppola
Daniel H
DH
Geschwind
Michael V
MV
Sofroniew
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001253:Astrocytes / Q000166:cytology* / Q000378:metabolism; D049109:Cell Proliferation; D017353:Gene Deletion; D005838:Genotype; D005978:Glutathione / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008564:Membrane Potentials; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction
D000975:Antioxidants; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D000255:Adenosine Triphosphate; D005978:Glutathione