SMOC Binds to Pro-EGF, but Does Not Induce Erk Phosphorylation via the EGFR.
In an attempt to identify the cell-associated protein(s) through which SMOC (Secreted Modular Calcium binding protein) induces mitogen-activated protein kinase (MAPK) signaling, the epidermal growth factor receptor (EGFR) became a candidate. However, although in 32D/EGFR cells, the EGFR was phosphorylated in the presence of a commercially available human SMOC-1 (hSMOC-1), only minimal phosphorylation was observed in the presence of Xenopus SMOC-1 (XSMOC-1) or human SMOC-2. Analysis of the commercial hSMOC-1 product demonstrated the presence of pro-EGF as an impurity. When the pro-EGF was removed, only minimal EGFR activation was observed, indicating that SMOC does not signal primarily through EGFR and its receptor remains unidentified. Investigation of SMOC/pro-EGF binding affinity revealed a strong interaction that does not require the C-terminal extracellular calcium-binding (EC) domain of SMOC or the EGF domain of pro-EGF. SMOC does not appear to potentiate or inhibit MAPK signaling in response to pro-EGF, but the interaction could provide a mechanism for retaining soluble pro-EGF at the cell surface.
FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America.
J Terrig
JT
Thomas
FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America.
Lina
L
Chhuy-Hy
FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America.
Kristin R
KR
Andrykovich
FDA/Center for Biologics Evaluation and Research, Division of Cellular and Gene Therapies Office of Cellular, Tissue, and Gene Therapies, Silver Spring, MD, United States of America.
Malcolm
M
Moos
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004625:Embryo, Nonmammalian; D004815:Epidermal Growth Factor / Q000235:genetics / Q000378:metabolism*; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D015676:Osteonectin / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013045:Species Specificity; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D015676:Osteonectin; D011498:Protein Precursors; D011994:Recombinant Proteins; C543141:SMOC1 protein, Xenopus; C468135:SMOC1 protein, human; C476827:SMOC2 protein, human; D029867:Xenopus Proteins; C042652:epidermal growth factor precursor; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3