Netrin-1, Recombinant, Human, Fc Chimera (NTN1, NTN1L, Netrin 1)

Human Netrin-1 (netr: Sanskrit for "one who guides") is a 75kD glycoprotein that is closely related to the laminin y domain and functions as a chemoattractive or chemorepulsive guidance cue in the central nervous system (CNS) during development (1-2). The protein is synthesized as a 604aa precursor that contains a 24aa signal sequence and a 580aa mature chain. Residues 46-283 constitute a laminin N-terminal domain (domain VI), while, 285-453 make up three laminin-type epidermal growth factor-like domains. There is a final domain that runs from aa487-601 that qualifies as a Netrin- 1 like domain. It is also known as domain C in the context of C. elegans. There are four potential sites for N-linked glycosylation. Human Netrin-1 is 99% aa identical to mouse and rat Netrin-1. Netrin-1 is expressed in adult and embryonic tissues. In the adult, the protein is expressed in Schwann cells, oligodendrocytes and multiple neurons. In embryonic tissues, Netrin-1 is found in somatic mesoderm, heart, branchial pouch, and neuroepithelium. Netrin-1 is a secreted protein that, in addition to its involvement in outgrowth and migration orientation in the developing CNS, plays a significant role in the morphogenesis of endothelial cells and vascular smooth-muscle cells. It is also involved in the processes of cytoskeleton reorganization, angiogenesis, epithelial cell adhesion, and cell migration in the lungs, mammary gland, and pancreas (1, 3). Netrin-1 effects are controlled through different transmembrane receptors (2). Four of the receptors exist in the Unc-5 (Unc=uncontrolled behaviorally) family of proteins, and these include Unc5h1, Unc5h2, Unc5h3/RCM, and Unc5h4. There are also two receptors that belong to the UNC-40 family of molecules. The first is DCC (deleted in colorectal cancer), and the second is neogenin (newly-generated). UNC-5 receptors are noted to mediate the attraction response of axons and netrins. However, UNC-5 molecules, when co-expressed with DCC in the presence of Netrin-1, will mediate repulsion by varying cellular calcium levels (3). The adenosine A2b receptor may also be involved in chemoattraction, either by binding directly with Netrin-1 or by serving as a co-receptor for DCC. These receptors are known as dependence receptors because they depend on their ligand, in this case Netrin-1, for survival (4). Unbound, the receptors induce a specific death signal (4). It is the dysregulation of these receptor systems that may have important roles in tumor biology. DCC and UNC5 proteins make up a system for either initiating or inhibiting apoptosis (4), and it is now believed that Netrin-1 and its dependence receptors play a major role in tumor biology (4-6). Source: Recombinant corresponding to aa22-604 (HPGGGSGGGSGGGS) of human Netrin-1, fused with 6-His tag at N-terminal, expressed in mouse myeloma cell line, NS0. Molecular Weight: ~67.5kD, Endotoxin Level: <1EU/1ug (LAL), Biological Activity: Measured by its binding ability in a functional ELISA. When recombinant rat UNC5H2 Fc Chimera is immobilized at 5ug/ml, recombinant human Netrin-1 binds with an apparent KD < 1nM., Measured in a cell proliferation assay using RT4-D6P2T rat Schwann cells (ATCC: CRL-2768). The ED50 for this effect is typically 0.5-2ug/ml. Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.