Interferon-stimulated gene expression in STAT1 knockout cells

STAT1 plays a cental role in the induction of interferon-stimulated genes, but interferon alpha can activate a STAT1-independent pathway that leads to gene expression. We performed microarray analysis to examine whether like interferon alpha, interferon lambda, a newly discovered interferon, can induce the expression of interferon-stimulated genes in the absence of STAT1. Control and STAT1 knockout Huh-7.5 hepatoma cells were left untreated or treated with 1000 U/ml of human interferon alpha 2a or interferon lambda 1 (PBL) for 24 h, and total RNA was extracted. Sense-strand DNA was generated from 200 ng of total RNA, fragmented, and labeled using a GeneChip WT Plus Reagent Kit (Affymetrix). Six samples were obtained and each sample was anlyzed using one GeneChip.