Bmi1 Is Down-Regulated in the Aging Brain and Displays Antioxidant and Protective Activities in Neurons
Figure 3
BMI1 is down-regulated in the aging human brain and retina.
(A) Immunohistochemistry on human brain (hippocampus) sections using anti-Bmi1 (brown) and anti-GFAP (pink) antibodies. BMI1 is expressed in neurons, but not in GFAP+ astrocytes, and expression is highly reduced in old brain neurons. Note the virtual absence of BMI1 labeling in some neurons (red arrowheads). Scale bars; 20 µm. (B) Immunofluorescence analysis of BMI1 expression in the human retina (23 years old, frozen sections). BMI1 is highly expressed in human photoreceptors (white arrowheads), which cell body lies in the outer nuclear layer (ONL), while its expression is weaker in neurons of the inner nuclear (INL) and ganglion cell (GCL) layers (red arrowheads). Scale bars; 20 µm. (C) Human retina samples were analyzed by Western blot for BMI1 expression and protein content was normalized using β-actin. BMI1 protein levels are reduced in old retinas (65–75 years). Results are Mean ± s.d. (n = 2–5 retinas per group; *P<0.05). (D)Immunofluorescence analysis of GFAP and P16INK4A expression in young and old human retinas. Note increased GFAP and P16INK4A immunoreactivity in the old retinas. Scale bars; 20 µm.