Figure 1.
Stress granule and P-body assembly and interference by viruses.
Virus infection causes stress at multiple levels that reduces host translation through activation of eIF2 kinases or other means and converts active polysome mRNPs into stalled translation initiation complex mRNPs. A complex series of events involving nucleation of several stress granule marker proteins such as G3BP, Tia-1/TIAR, and HDAC6 plus transport on microtubules (MT) leads to aggregates of translation initiation complex mRNPs in stress granules. Alternatively, mRNPs can be stripped of initiation factors and ribosome subunits, associate with GW182, undergo Pan2/3-mediated deadenylation, MT transport, and association of other RNA decay factors (e.g., Xrn1, Dcp1a, DDX6, GW182 and Lsm components of the exosome), and become concentrated in P-bodies. Decapping and decay occur outside P-bodies and also within them. Specific points/proteins where viruses interact with and inhibit RNA granule assembly pathways are shown.