Fig. 2.

ACE2 shedding was not responsible for influenza virus-induced ACE2 protein downregulation, and TACE knockdown did not affect the levels of ACE2 downregulation. The cell culture supernatants of CNE-2E (a) and 293T-ACE2 (b) cells were obtained at 24 hpi after infection with PR8 or CA07 strains at a moi of 5; Control cells were mock-infected with AF. The levels of ACE2 protein were detected by Western blotting. Densitometric analysis normalized to the corresponding control levels was expressed as fold change. (c, d) CNE-2Z cells were infected with the retroviruses either expressing shTACE or shCtrl. After 48 h, cells were infected with PR8 or CA07. The cell lysates were taken at 24 hpi, and then ACE2 protein levels were detected by Western blotting. (e) Real-time PCR analyzed TACE mRNA expression levels after a 48 h of retroviral transduction. All graphs represent the means ± S.E.M. *P < 0.05 were considered statistical significant.