The EGFR (ERBB) family provides a model system for receptor signaling, oncogenesis, and the development of targeted therapeutics. Heterodimers of the ligand-binding-deficient ERBB2 (HER2) receptor and the kinase impaired ERBB3 (HER3) create a potent mitogenic signal, but the phosphorylation of ERBB2 in this context presents a challenge to established models of phosphorylation in trans. Higher order complexes of ERBB receptors have been observed biophysically and offer a theoretical route for ERBB2 phosphorylation, but it is not clear whether such complexes provide functionality beyond the constituent dimers. We now show that a previously selected inhibitory RNA aptamer that targets the extracellular domain (ECD) of ERBB3 acts by sterically disrupting these higher order interactions. Ligand binding, heterodimerization, phosphorylation of ERBB3, and AKT signaling are only minimally affected, whereas ERBB2 phosphorylation and MAPK signaling are selectively inhibited. The mapping of the binding site and creation of aptamer-resistant point mutants are consistent with a model of side-by-side oriented heterodimers to facilitate proxy phosphorylation, even at very low endogenous levels of receptors (below 10,000 receptors per cell). Additional modes of signaling with relevance to pathological ERBB expression states emerge at high receptor levels. Hence, higher order complexes of nonoverexpressed ERBB receptors are an integral and qualitatively distinct part of normal ERBB2/ERBB3 signaling. This mechanism of activation has implications for models of allosteric control, specificity of interactions, possible mechanisms of cross-talk, and approaches to therapeutic intervention that at present often generate experimental and clinical outcomes that do not reconcile with purely canonical, dimer-based models.
Pharmacology, Toxicology and Pharmaceutical Science
3
3%
Other
4
4%
Unknown
14
14%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 4. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 03 May 2018.
All research outputs
#10,721,406
of 34,400,738 outputs
Outputs from Proceedings of the National Academy of Sciences of the United States of America
#78,804
of 118,992 outputs
Outputs of similar age
#69,230
of 212,779 outputs
Outputs of similar age from Proceedings of the National Academy of Sciences of the United States of America
#647
of 980 outputs
Altmetric has tracked 34,400,738 research outputs across all sources so far. This one has received more attention than most of these and is in the 67th percentile.
So far Altmetric has tracked 118,992 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 40.1. This one is in the 32nd percentile – i.e., 32% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 212,779 tracked outputs that were published within six weeks on either side of this one in any source. This one has gotten more attention than average, scoring higher than 65% of its contemporaries.
We're also able to compare this research output to 980 others from the same source and published within six weeks on either side of this one. This one is in the 31st percentile – i.e., 31% of its contemporaries scored the same or lower than it.
