Figure 3

ATM kinase activation during early infection is necessary for autophagy and ER stress. (a) Western blot of whole-cell lysates, obtained from different times of infection, shows an increase in ATM phosphorylation (S1981) during the early stages (2–12 HPI) of infection. We also see gradual increase in LC3 lipidation from 12 up to 36 HPI, when induction reaches its highest level. β-Tubulin is used as loading control. (b) Phosphorylation of histone H1, a downstream target of ATM substrate CDK5, increases during dengue (Den) infection compared with mock-infected cells (compare Den with Mock). The maximum activation of H1 at 24 HPI corroborates the activation of ATM in the early stages of infection. Actin is used as a loading control. (c) CHOP RNA increases (decrease in Ct values; each unit represents a twofold difference in total RNA) during early infection (12 HPI Den). ATMi pretreatment prevents CHOP transcription at 12 HPI. Thus, an early ATM activation is responsible for ER stress induction at early stages of infection