Many tissues such as muscle, skin, liver, and peripheral nerve, have remarkable ability to repair and regrow after injury. However, the CNS (brain and spinal cord) is limited in its ability to repair or regrowth causing permanent brain damage or paralyses. An inhibitory myelin protein, Nogo (Neurite outgrowth), has been cloned and characterized. It may help block the regeneration of the CNS. Nogo is the 4th member of reticulon (Rtn) family. There are three alternative isoforms of Nogo: 1)Nogo-A (full length human protein 1192aa; calculated mol wt 135kD; rat 1163 aa), 2)Nogo-B (373aa; ~37K, lacks186-1004aa within the extracellular domain), and
3)Nogo-C (199aa; ~25 K, similar to rat vp20 and foocen-s; lacks 186-1004aa but which has a smaller, alternative N-terminal domain). Nogo-A has a putative extracellular domain of 1024aa, 2-3 TM domains, and a short C-terminus of 43aa. Nogo-A is localized to the CNS-myelin, and is highly expressed in oligodendorcytes but not by Schwann cells. Nogo-B and Nogo-C have been found in several non-neuronal tissues (skeletal muscle, kidney, skin, lung, and spleen). They may be the 35kD protein recognized by IN-1 antibody. Full length Nogo-A has the strongest inhibitory activity. It may be the 250kD protein recognized by the IN-1 antibody. The N-terminus of Nogo A is unique, whereas the C-terminus has sequence homology with the reticulon family. Nogo-A has endoplasmic reticulum retention signal sequence. It is not clear how Nogo-A contacts axons and reaches the membrane of oligodendorcytes. A 66aa hydrophilic region of Nogo, located between the two TM domains, has the most inhibitory properties of Nogo.
In contrast to Nogo, Rtn 1, -2, and 3 do not inhibit axonal regeneration. A 25-aa inhibitory peptide sequence (designated as Nogo-P4; rat Nogo 1056-1080 aa or 31-55aa of the 66aa active peptide) is sufficient to produce core inhibitory properties (see GrandPre, T. et al., (2000). This 66-aa region also has the least similarity to Rtn proteins. The corresponding Rtn-P4 peptide sequence has no activity. Peptide sequence 1-40aa of the Nogo-66, designated NEP1-40, acts as competitive antagonist of NgR and blocks Nogo-66 or CNS myelin inhibition of axonal outgrowth in vitro. Intrathecal administration of NEP1-40 to rats with mid thoracic spinal cord hemisection results in significant axon growth of corticospinal tract.
Storage and Stability:
May be stored at 4 degrees C for short-term only. For long-term storage, store at -20 degrees C. Aliquots are stable for at least 6 months at -20 degrees 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.