Inter-conversion of neuregulin2 full and partial agonists for ErbB4

Abstract

The EGF family hormone NRG2beta potently stimulates ErbB4 tyrosine phosphorylation and coupling to IL3 independence. In contrast, the NRG2alpha splicing isoform has lower affinity for ErbB4, does not potently stimulate ErbB4 phosphorylation, and fails to stimulate ErbB4 coupling. Here we investigate these differences. The NRG2beta Q43L mutant potently stimulates ErbB4 phosphorylation but not ErbB4 coupling to IL3 independence. This failure to stimulate ErbB4 coupling is not due to differential ligand purity, glycosylation, or stability. The NRG2alpha K45F mutant potently stimulates ErbB4 phosphorylation but not ErbB4 coupling to IL3 independence. Thus, this failure to stimulate ErbB4 coupling is not due to inadequate affinity for ErbB4. In contrast, the NRG2alpha L43Q/K45F mutant stimulates ErbB4 coupling, even though it does not have greater affinity for ErbB4 than does NRG2alpha/K45F. Collectively, these data indicate that Gln43 of NRG2beta is both necessary and sufficient for NRG2 stimulation of ErbB4 coupling to IL3 independence.

Epiregulin: Roles in normal physiology and cancer

“…Phe44 of mature human epiregulin corresponds to a hydrophobic amino acid residue essential for EGF family hormones to bind with high affinity to ErbB4, including Tyr45 of neuregulin-1beta, Phe45 of neuregulin-2beta, and Val44 of betacellulin (Table 2) [12, 21–24]. Glu42 of epiregulin corresponds to a Gln or Glu residue critical for the activity of efficacious ErbB4 ligands, including Gln43 of neuregulin-1beta, Gln43 of neuregulin-2beta, and Glu42 of betacellulin (Table 2) [5, 7, 12, 15, 21, 22, 24–26].…”

“…Glu42 of epiregulin corresponds to a Gln or Glu residue critical for the activity of efficacious ErbB4 ligands, including Gln43 of neuregulin-1beta, Gln43 of neuregulin-2beta, and Glu42 of betacellulin (Table 2) [5, 7, 12, 15, 21, 22, 24–26]. Thus, it appears that epiregulin and other high-affinity ErbB4 ligands share a common binding site on ErbB4 and that epiregulin and other efficacious ErbB4 ligands stimulate ErbB4 signaling in essentially the same manner.…”

Activation of ErbB3, EGFR and Erk is essential for growth of human breast cancer cell lines with acquired resistance to fulvestrant

“…1.25 nM (an 8 kDa peptide). Recombinant GST-NRG2β (hrg2β) was produced by Dr. Riese as described earlier [21] and we used 50 nM of this hrg2β fusion protein.…”

A high throughput, interactive imaging, bright‐field wound healing assay

“…To test the automated wound healing assay, we measured the healing response to the known growth factor neuregulin-2β (15,16). MCF7 cells were seeded in 96-well plates as described previously.…”

“…The wells were washed and the medium was replaced by basal medium supplemented with 0, 3, 30 or 100 nM neuregulin-2β. Neuregulin-2β was purified using the protocol developed by the Riese laboratory (15,16). The plate was then imaged in bright field at 0, 24, 48, 72, and 96 h. The wound area was measured using the texture segmentation algorithm for each well at each time point.…”