TRIM68 is structurally similar to TRIM21 and down-regulates type I IFN production downstream of TBK1.

<p>(A) Human TRIM68 and TRIM21 amino acid sequence alignment using T-Coffee (<a href="http://tcoffee.crg.cat/apps/tcoffee/do:regular" target="_blank">http://tcoffee.crg.cat/apps/tcoffee/do:regular</a>). An * (asterisk) indicates positions which have a single, fully conserved residue. A: (colon) indicates conservation between groups of strongly similar properties - scoring >0.5 in the Gonnet PAM 250 matrix. A. (period) indicates conservation between groups of weakly similar properties - scoring <0.5 in the Gonnet PAM 250 matrix. (B–C) HeLa cells were transfected with 40 ng full-length IFN-β promoter, empty vector (EV) control and increasing amounts of TRIM68 as indicated for 18 hr and were then stimulated with 20 µg/ml poly(I:C) for 24 hr. In all other cases HEK293T cells were transfected with 40 ng full-length IFN-β promoter and were co-transfected with 50 ng of the relevant promoter drivers TRIF, TBK1, IRF3 (B), or dsRNA, RIG-I, MAVS (C) as well as with empty vector (EV) control and increasing amounts of TRIM68 as indicated. Cells were assayed for relative fold increase of reporter gene activity 18–24 hr post-transfection. (D) HeLa cells were transiently transfected with 1 µg of TRIM68 together with 1 µg/ml 5′ppp-dsRNA for 6 and 24 hr or 18 hr later with 20 µg/ml poly(I:C) for 6 and 24 hr before supernatants were collected for RANTES ELISA. In all cases presented data is graphed from the average of three separate experiments ± S.E.M. *p<0.05 was considered significant.