Figure 4.The up-regulation of ISG1 5 expression in cells with short telomeres does not depend on interferon beta1 (INFB1). (A) Q-PCR analysis
of mRNA levels of INFB1 in human fibroblasts with different telomere
length (BJ-18 to BJ-83). Results from at least three separate experiments
are shown as means ± SEM. GAPDH was used as an internal normalization
control. All values were then normalized to the level (=100%) of mRNA in
young cells (PD18) with long telomeres. Results show an increase of INFB1
expression with telomere shortening. (B) Stable knock down of INFB1
by shRNA in BJ cells with short telomeres did not reduce the expression of
ISG15. mRNA levels of ISG15 and INFB1 were quantified by q-PCR. (C)
Western blot showing that blocking antibodies to both IFN α and β
reduced the levels of both free and conjugated ISG15 in young BJ
fibroblasts, but failed to reduce expression in old cells with short
telomeres. Young (BJ-18) and old (BJ-76) cells were treated with neutralizing
antibodies against INFA and INFB1.
