A Tyrosine-Based Signal Plays a Critical Role in the Targeting and Function of Adenovirus RID Protein

Department of Physiology and Biophysics, Case Western Reserve University Cancer Center, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA.
Journal of Virology (Impact Factor: 4.44). 11/2007; 81(19):10437-50. DOI: 10.1128/JVI.00399-07
Source: PubMed


Early region 3 genes of human adenoviruses contribute to the virus life cycle by altering the trafficking of cellular proteins
involved in adaptive immunity and inflammatory responses. The ability of early region 3 genes to target specific molecules
suggests that they could be used to curtail pathological processes associated with these molecules and treat human disease.
However, this approach requires genetic dissection of the multiple functions attributed to early region 3 genes. The purpose
of this study was to determine the role of targeting on the ability of the early region 3-encoded protein RIDα to downregulate
the EGF receptor. A fusion protein between the RIDα cytoplasmic tail and glutathione S-transferase was used to isolate clathrin-associated adaptor 1 and adaptor 2 protein complexes from mammalian cells. Deletion
and site-directed mutagenesis studies showed that residues 71-AYLRH of RIDα are necessary for in vitro binding to both adaptor
complexes and that Tyr72 has an important role in these interactions. In addition, RIDα containing a Y72A point mutation accumulates
in the trans-Golgi network and fails to downregulate the EGF receptor when it is introduced into mammalian cells as a transgene. Altogether,
our data suggest a model where RIDα is trafficked directly from the trans-Golgi network to an endosomal compartment, where it intercepts EGF receptors undergoing constitutive recycling to the plasma
membrane and redirects them to lysosomes.

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    • "In addition to these studies, we have previously reported that RIDα is necessary and sufficient for EGFR down-regulation (Hoffman et al., 1990; Cianciola et al., 2007). However, this result is controversial, and other investigators contend that RIDβ is also necessary based on results obtained by infecting tissue culture cells simultaneously with multiple adenovirus mutants (Tollefson et al., 1991). "
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