Figure 6: FMRP knockdown leads to nuclear retention of RNP components.

(a) FMRP knockdown leads to nuclear retention of vRNAs but does not affect viral mRNA trafficking. A549 cells were transfected with control or FMRP-specific siRNAs. After 48 h, cells were infected with PR8 virus for 9 h and subjected to in situ hybridization assays using vRNA-specific (left) or mRNA-specific (right) probes against the M1 gene. Scale bar, 10 μm. (b) Statistical analysis of RNA distribution in (a) (mean±s.d. of two independent experiments, *P<0.05, n.s., not significant, two-tailed Student’s t-test). (c,d) FMRP knockdown impedes PA nuclear export but does not affect NEP nuclear export. Control or FMRP-knockdown cells were infected with PR8 virus for 9 h followed by immunofluorescence analysis with indicated antibodies. Scale bar, 10 μm. (e) Statistical analysis of viral protein distribution in (c) and (d). Quantitative analyses were calculated by ratios of NP nuclear-retained cells/total infected cells (mean±s.d. of three independent experiments, *P<0.05, **P<0.01, n.s., not significant, two-tailed Student’s t-test). (f) Proposed model for the role of FMRP during influenza virus replication.