FIG. 5.
HIF is necessary for the hypoxic increase in replicative life span. (a) Transcriptional activity of PHLFs stably expressing HIF-DN or the vector control pLXIN was assayed with a firefly luciferase reporter construct driven by 3×HRE and with a control Renilla luciferase construct driven by the thymidine kinase promoter. Relative luciferase values were determined by normalizing values of firefly to Renilla luciferase (n = 3). (b) Telomerase activity of PHLFs stably expressing HIF-DN or pLXIN exposed to 21% O2 or 1.5% O2 (n = 3). PHLFs stably expressing HIF-DN or pLXIN were grown in 21% O2 (c) or 1.5% O2 (d), and their PDs were monitored postinfection.