Nucleocytoplasmic Trafficking Perturbation Induced by Picornaviruses

Figures

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  Figure 1. The nuclear pore complex and nucleocytoplasmic transport of proteins.

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  Figure 2. Picornavirus-induced alteration of the nuclear pore complex. (A) Illustration of the NPC showing alterations triggered by picornaviruses. The proteins forming the different nuclear pore components and some soluble phase proteins are indicated. FG-nucleoporins are in bold characters. Alterations triggered by picornaviruses are depicted as follows. Blue scissors: caspase-dependent degradation (e.g., importins); Red scissors: virus-dependent cleavage; P: phosphorylation. The model proposed to account for NUP phosphorylation by cardioviruses is illustrated: a complex formed between the L protein, RAN and exportins would recruit kinases (e.g., ERK1/2 and p38) to the NPC, where these kinases would induce the phosphorylation of FG-nucleoporins. (B) Zoom on FG-nucleoporins molecular modifications by picornaviruses. Enteroviruses use their 2Apro and 3Cpro to cleave the FG domains, thereby inducing an opening of the pore. Cardioviruses use their L protein to trigger the phosphorylation of the FG-rich domains of FG-nucleoporins, thereby inducing disorganization of the pore.

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  Figure 3. Consequences of protein and RNA trafficking perturbation induced by Picornaviruses. (1) Cytoplasmic retention of transcription factors (STAT1/2, IRF3) thereby inhibiting transcriptional induction of cellular genes: e.g., karyopherin subunit α1 cleavage prevents the translocation of STAT1/2 into the nucleus. (2) Nuclear proteins are delocalized to the cytoplasm, where they interact with the viral genome to promote viral genome translation or replication. (3) Blocking of mRNA export, preventing the translation of antiviral proteins, and making the translation machinery available for viral mRNA translation.