Related Experiment Videos
Caspase-9 activation in hypoxic human corneal epithelial cells.
M Kurpakus-Wheater1, R Sexton, M L McDermott
1Department of Anatomy and Cell Biology, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, Michigan, USA. mkurpaku@med.wayne.edu
Apoptosis : an International Journal on Programmed Cell Death
|January 24, 2004
Summary
Hypoxia upregulates caspase-9 activity in corneal epithelium via the mitochondrial pathway, while suppressing caspase-8 activity, suggesting a complex apoptosis regulation under low oxygen conditions.
Area of Science:
- Ophthalmology
- Cell Biology
- Molecular Biology
Background:
- Corneal epithelium is susceptible to hypoxic stress.
- Apoptosis regulation in corneal cells under hypoxia is not fully understood.
- Caspases play critical roles in programmed cell death.
Purpose of the Study:
- To investigate the impact of hypoxia on caspase-8 and caspase-9 gene and protein expression and activity.
- To elucidate the apoptotic pathways involved in corneal epithelium under hypoxic conditions.
Main Methods:
- Human corneal epithelial cells (HCEC) were cultured under hypoxic (2% oxygen) and normoxic conditions.
- cDNA expression array analysis was performed to assess mRNA levels of apoptosis-related genes.
- Western blot, ELISA, and fluorometric assays were used to measure protein expression and caspase activity.
Main Results:
- Hypoxia did not alter caspase-8 or -9 gene/protein expression but significantly increased caspase-9 activity.
- Caspase-8 activity was significantly suppressed under hypoxic conditions.
- TNFalpha and TNFR-1 expression decreased, while FasL expression increased in hypoxic HCEC.
Conclusions:
- Hypoxia upregulates caspase-9 activity in corneal epithelium, indicating apoptosis via the mitochondrial pathway.
- Suppressed caspase-8 activity may result from reduced TNFalpha/TNFR-1 signaling, inhibiting death complex formation.
- These findings reveal distinct caspase regulation mechanisms in corneal epithelium under hypoxic stress.