Fig. 5: ER targeting specifies the TENT5-mediated re-adenylation of synthetic mRNAs.

a, eDRS-measured mRNA-1273 poly(A) length distribution 24 h after administration to mock (left) or Fndc3a- and Fndc3b-depleted mBMDMs. Average distributions from three different siRNAs in two replicates. b, cDNA-seq-measured poly(A) length distribution for mRNA-1273 (top) and BNT162b2 (bottom) co-transfected to wild-type mBMDMs in equal amounts, showing cytoplasmic (C) and membrane (M) fractions over time (up to 36 h). c, cDNA-seq-measured OVA reporter poly(A) length distribution in mBMDMs transfected with mRNAs that have BNT162b2 or mRNA-1273 UTRs and BNT162b2-like poly(A) tails (with terminal mΨCmΨAG) for up to 48 h. The type of UTRs in the reporter is indicated at the top. d,e, PfCSP reporter poly(A) length distribution in mBMDMs transfected with mRNAs that have BNT162b2-like poly(A) tails with a terminal mΨCmΨAG for up to 24 h, analysed with either cDNA-seq (d) or eDRS (e). Type of UTRs in the reporter indicated at the top. For all panels, reads are divided into those with (blue) or without (green or grey) an mΨCmΨAG sequence, with median values and fractions of elongated or shortened tails shown. Average distributions for two biological experiments (a–d) or a single biological experiment (e). Bottom panels show the relative abundance of each group, with group sizes indicated. P values calculated with two-sided Wilcoxon test (on reads lacking mΨCmΨAG) with Benjamini–Hochberg correction. See also Extended Data Figs. 6–9.