Different STAT Transcription Complexes Drive Early and Delayed Responses to Type I IFNs.

ABSTRACT: IFNs, which transduce pivotal signals through Stat1 and Stat2, effectively suppress the replication of Legionella pneumophila in primary murine macrophages. Although the ability of IFN-? to impede L. pneumophila growth is fully dependent on Stat1, IFN-?? unexpectedly suppresses L. pneumophila growth in both Stat1- and Stat2-deficient macrophages. New studies demonstrating that the robust response to IFN-?? is lost in Stat1-Stat2 double-knockout macrophages suggest that Stat1 and Stat2 are functionally redundant in their ability to direct an innate response toward L. pneumophila. Because the ability of IFN-?? to signal through Stat1-dependent complexes (i.e., Stat1-Stat1 and Stat1-Stat2 dimers) has been well characterized, the current studies focus on how Stat2 is able to direct a potent response to IFN-?? in the absence of Stat1. These studies reveal that IFN-?? is able to drive the formation of a Stat2 and IFN regulatory factor 9 complex that drives the expression of a subset of IFN-stimulated genes, but with substantially delayed kinetics. These observations raise the possibility that this pathway evolved in response to microbes that have devised strategies to subvert Stat1-dependent responses.

SUBMITTER: Abdul-Sater AA 

PROVIDER: S-EPMC4617678 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature