LARP4 promotes accumulation of interferon-induced innate immune mRNAs. ( A ) Northern blot analysis of two ISG mRNAs, IFIT1 and ISG15 after transfection-mediated induction by IFN-stimulating nucleic acids, and + / - co transfection with LARP4, as indicated above the lanes. Bottom panels are stained gels prior to transfer. ( B ) Quantitation of biological triplicate northern blot data, normalized by GAPDH, with the poly(I:C) +, LARP4 - sample (annotated with # above the bar) set to 100%; error bars represent 95% confidence interval. P values were calculated using a 2-tailed Welch's T-test with unequal variance. ( C ) Northern blot of IFIT1 and LARP4 from total RNA 48 hr after transfection of 0, 2, 4 or 6 µg of 1 kb AT-rich DNA in <t>6-well</t> format (the total DNA amount for this component of the transfection was maintained at 6 µg with carrier pUC19), plus 2.5 µg pFLAG-LARP4 (+) or empty pFLAG vector ( - ) as indicated. ( D ) Top: schematic of LARP4 showing its two PABP-interaction motifs, PAM2w and PBM, the La-module comprised of LaM (La motif) and RRM-L4, and the RACK-1 interaction region (RIR). The N-terminal region (NTR) which is responsible for poly(A)-binding ( Cruz-Gallardo et al., 2019 ), is also indicated. Middle: Northern blot after co-transfection of 1 kb AT-rich DNA or pUC19 and various LARP4 constructs indicated above the lanes. Bottom: Western blot analysis of protein from the same cells.
{}