Molecular basis for vulnerability to mitochondrial and oxidative stress in a neuroendocrine CRI-G1 cell line.
BACKGROUND
Many age-associated disorders (including diabetes, cancer, and neurodegenerative diseases) are linked to mitochondrial dysfunction, which leads to impaired cellular bioenergetics and increased oxidative stress. However, it is not known what genetic and molecular pathways underlie differential vulnerability to mitochondrial dysfunction observed among different cell types.


RESULTS
Starting with an insulinoma cell line as a model for a neuronal/endocrine cell type, we isolated a novel subclonal line (named CRI-G1-RS) that was more susceptible to cell death induced by mitochondrial respiratory chain inhibitors than the parental CRI-G1 line (renamed CRI-G1-RR for clarity). Compared to parental RR cells, RS cells were also more vulnerable to direct oxidative stress, but equally vulnerable to mitochondrial uncoupling and less vulnerable to protein kinase inhibition-induced apoptosis. Thus, differential vulnerability to mitochondrial toxins between these two cell types likely reflects differences in their ability to handle metabolically generated reactive oxygen species rather than differences in ATP production/utilization or in downstream apoptotic machinery. Genome-wide gene expression analysis and follow-up biochemical studies revealed that, in this experimental system, increased vulnerability to mitochondrial and oxidative stress was associated with (1) inhibition of ARE/Nrf2/Keap1 antioxidant pathway; (2) decreased expression of antioxidant and phase I/II conjugation enzymes, most of which are Nrf2 transcriptional targets; (3) increased expression of molecular chaperones, many of which are also considered Nrf2 transcriptional targets; (4) increased expression of β cell-specific genes and transcription factors that specify/maintain β cell fate; and (5) reconstitution of glucose-stimulated insulin secretion.


CONCLUSIONS
The molecular profile presented here will enable identification of individual genes or gene clusters that shape vulnerability to mitochondrial dysfunction and thus represent potential therapeutic targets for diabetes and neurodegenerative diseases. In addition, the newly identified CRI-G1-RS cell line represents a new experimental model for investigating how endogenous antioxidants affect glucose sensing and insulin release by pancreatic β cells.
Department of Pathology, University of California San Francisco, San Francisco, California, United States of America.
Natasha
N
Chandiramani
Xianhong
X
Wang
Marta
M
Margeta
D002460:Cell Line; D020869:Gene Expression Profiling; D055106:Genome-Wide Association Study; D006801:Humans; D050417:Insulin-Secreting Cells / Q000378:metabolism; D007340:Insulinoma / Q000235:genetics / Q000473:pathology; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D051267:NF-E2-Related Factor 2 / Q000235:genetics*; D055099:Neuroendocrine Cells / Q000166:cytology*; D018384:Oxidative Stress / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics
D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human
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