title: The non-canonical NOTCH1 ligand Delta-like 1 homolog (DLK1) self interacts in mammals.
abstract: Delta-like 1 homolog (DLK1) is an imprinted gene, which is widely expressed during mammalian development and plays a pivotal role in differentiation of various tissue types. Most recently, we have shown that DLK1 interacts with NOTCH1, yet several Notch independent mechanisms have previously been suggested as well, but only poorly confirmed in a mammalian context. In the present study, we employed the mammalian two-hybrid (MTH) system, a genetic in vivo protein-protein interaction system, to show robust DLK1-DLK1, DLK1-FnI (Fibronectin) and DLK1-CFR (cysteine-rich FGF receptor) interactions, whereas the proposed DLK1-IGFBP1 interaction was not supported by MTH. Very little has previously been described on the DLK1 self-interaction. Herein, we showed by immunoprecipitation as well as Sulfo-SBED label transfer that the DLK1-DLK1 interaction likely is part of Dlk1's function in preadipocytes. Furthermore our data suggest that DLK1 interacts with itself through EGF domain 4 and 5, which is distinct from the recently described NOTCH1-DLK1 interaction, which occurs between EGF domain 5 and 6. This opens up the possibility that Notch independent mechanisms like the DLK1-DLK1 interaction may modulate the non-canonical NOTCH1-DLK1 interaction further complexing this system.
authors.affiliation: Laboratory of Molecular and Cellular Cardiology, Dep. of Clinical Biochemistry and Pharmacology, 5000 Odense C, Denmark; Cardiovascular and Renal Research (University of Southern Denmark), Winsloewparken 21(3rd), 5000 Odense C, Denmark.
authors.forename: Gunnhildur Ásta
authors.initials: GÁ
authors.lastname: Traustadóttir
authors.affiliation: Laboratory of Molecular and Cellular Cardiology, Dep. of Clinical Biochemistry and Pharmacology, 5000 Odense C, Denmark; Danish Center for Regenerative Medicine (Odense University Hospital), 5000 Odense C, Denmark.
authors.forename: Charlotte Harken
authors.initials: CH
authors.lastname: Jensen
authors.affiliation: Department of Inorganic and Organic Chemistry and Biochemistry, University of Castilla-La Mancha Medical School, Albacete, Spain.
authors.forename: Jose Javier
authors.initials: JJ
authors.lastname: Garcia Ramirez
authors.affiliation: Clinical Institute (University of Southern Denmark), 5000 Odense C, Denmark; Dep. of Clinical Biochemistry and Pharmacology (OUH), Denmark.
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Beck
authors.affiliation: Laboratory of Molecular and Cellular Cardiology, Dep. of Clinical Biochemistry and Pharmacology, 5000 Odense C, Denmark; Danish Center for Regenerative Medicine (Odense University Hospital), 5000 Odense C, Denmark; Clinical Institute (University of Southern Denmark), 5000 Odense C, Denmark.
authors.forename: Søren Paludan
authors.initials: SP
authors.lastname: Sheikh
authors.affiliation: Laboratory of Molecular and Cellular Cardiology, Dep. of Clinical Biochemistry and Pharmacology, 5000 Odense C, Denmark; Danish Center for Regenerative Medicine (Odense University Hospital), 5000 Odense C, Denmark; Cardiovascular and Renal Research (University of Southern Denmark), Winsloewparken 21(3rd), 5000 Odense C, Denmark. Electronic address: dandersen@health.sdu.dk.
authors.forename: Ditte Caroline
authors.initials: DC
authors.lastname: Andersen
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins; D005353:Fibronectins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D066329:Protein Aggregates; D011485:Protein Binding; D000072417:Protein Domains; D051881:Receptor, Notch1 / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D002135:Calcium-Binding Proteins; C512941:DLK1 protein, human; C512925:Dlk1 protein, mouse; D005353:Fibronectins; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins; D066329:Protein Aggregates; D051881:Receptor, Notch1; D017468:Receptors, Fibroblast Growth Factor
keywords: Delta-like 1 homolog (Dlk1); EGF-repeats; Ligand; Receptor; Self-interacting protein