Loss of ATM impairs proliferation in astrocytes. A,
astrocytes were isolated from the brains of newborn Atm+/+
and Atm-/- mice, and their growth curves were determined
by trypan blue staining at indicated days after initial seeding of cells. The
means ± S.D. of three independent experiments are shown. *,
p < 0.05 when Atm-/- astrocytes were compared
with Atm+/+ astrocytes. B, phase contrast
photomicrographs of Atm+/+ and Atm-/-
astrocytes following further incubation for 4 days (left panel). ATM
in C1 astrocytes was inactivated by ATM inhibitor KU55933, and knocked down
using ATM siRNA (right panel). Scale bars, 50 μm.
C, the proportions of senescent cells in Atm+/+
and Atm-/- astrocytes were determined by SA
β-galactosidase expression 2 days after cultivation. The means ±
S.D. of three independent experiments are shown. *, p <
0.05 when Atm-/- astrocytes were compared with
Atm+/+ astrocytes.