Recombinant Mouse WIF-1 Protein, CF

WIF-1 (Wnt Inhibitory Factor-1) is a secreted Wnt inhibitor. Like sFRPs (secreted Frizzled-related proteins), WIF-1 binds to Wnt proteins and inhibits their receptor binding, thus inhibiting all Wnt signaling pathways (1, 2). WIF-1 is synthesized as a 379 amino acid (aa) precursor that contains a 28 aa N-terminal signal sequence, a WIF domain (aa 38-177), 5 EGF-like repeats (aa 178-338), and a C-terminal hydrophilic domain (1). Mature mouse WIF-1 shares 95%, 99%, 87% and 85% aa sequence identity with human, rat, equine and Xenopus WIF-1, respectively. A potential 220 aa isoform with an alternate N-terminus that lacks the WIF domain is identical with the 379 aa form after aa 179 (3).  The WIF domain contains a phospholipid binding site that interacts with lipid-modified Wnt molecules, while a binding site for sulfated proteoglycans within the EGF repeats contributes to binding and inhibition (4). WIF-1 fine-tunes Wnt signaling by time- and location-specific expression in the fetal and postnatal mouse, especially during joint development and cardiomyogenesis (5-7). Binding of Wnts 3a, 4, 5, 7a, 9a and 11, with little or no binding to Wnts 5b, 7b, and 9b, has been shown (5). Binding and inhibition of other molecules in cartilage, such as CTGF (connective tissue growth factor), has also been shown (6). WIF-1 expression is up‑regulated by BMP-4/ Smad1 signaling during fetal lung development (8). WIF-1 functions as a tumor suppressor in cancers of the prostate, breast, lung, bladder, cervix, liver and brain (9-12). Its down‑regulation by promoter hypermethylation is detected in a variety of tumors (11-13). WIF‑1 anti‑tumor effects include antagonizing angiogenesis, growth and invasion, and inducing apoptosis, senescence, or differentiation (2, 10-13). WIF-1 has been used experimentally to antagonize tumors or regulate developmental Wnt activities (10-15).