Antiserum against neurite outgrowth factor in chick gizzard extract and its inhibitory effect on neuritic response in cultured ciliary neurons

Extracellular matrix proteins with neurite promoting activity and their receptors

Characteristic features of the nervous system converge into network formation during the development. The neurons recognize precisely their target cells and form synapses, and these steps are complex, but well organized spatially and temporally. The neurite promotion from the neurons is one of the most important events for synapse formation. It is well known that extracellular matrix proteins such as laminin and their receptors, and cell adhesion molecules such as NCAM participate in cell migration and synaptic formation. We have isolated a neurite outgrowth factor (NOF) which promotes neurite outgrowth from various neurons and belongs to laminin family, and also its receptor which is identified to be an immunoglobulin superfamily protein by cDNA cloning. This ligand-receptor system is a unique example that a receptor with immunoglobulin-like structure interacts with an extracellular matrix protein.

Involvement of a receptor for neurite outgrowth factor (NOFR) in cerebellar neurogenesis

A receptor for neurite outgrowth factor (82 kDa membrane protein, NOFR) was detected in the developing chick cerebellum by immuno- and ligand blots. In immunohistochemical study, NOFR was maximally expressed in the external granular layer of cerebellum at embryonic day 10-12 and gradually decreased until embryonic day 18. Neurite outgrowth and cell migration induced by NOF from cerebellar explants were completely suppressed by the addition of anti-NOFR IgG. These results suggest that NOFR plays an important role in the cerebellar neurogenesis.

The formation of axonal pathways in developing cranial nerves

The roles of a variety of molecules including cell adhesion molecules and growth factors in the development of cranial nerves have begun to be understood in detail. In the course of embryonic development, cranial nerves are differentiated in concordance with the development of the metameric facial structure called 'ectomeres'. Each ectomere parallels the segmentation of the hindbrain called the 'rhombomere', in which pairs of metameric units cooperate to generate the repeating sequence of cranial branchiomotor nerves. A number of genes, including homeobox genes, are expressed in a rhombomere-specific pattern. For the formation of the olfactory nerve, it is suggested that several carbohydrate residues play important roles in receptor-target specificity. In the optic nerve, a combination of multiple cell adhesion molecules contributes to neurite growth in a developmental stage-specific manner. The development of the trigeminal nerve is under the control of both cell adhesion molecules and several growth factors. There is evidence that some of the adhesion molecules are expressed in a modality-specific way. There are also several molecules, such as 11p15 or TAG1/SNAP which are expressed only in selected cranial nerves. The growth rate of neurites also varies according to the individual nerves. Thus each cranial nerve has its own intrinsic properties and their outgrowth is the outcome of these properties and their interactions with surrounding non-neuronal tissues.

Purification and characterization of an 82-kD membrane protein as a neurite outgrowth factor binding protein: possible involvement of NOF binding protein in axonal outgrowth in developing retina

Neurite outgrowth factor (NOF) is a glycoprotein isolated from an extract of gizzard that induces neurite outgrowth from cultured retinal or ciliary ganglionic (CG) neurons. We have reported that a glycoprotein of approximately 82 kD solubilized from gizzard muscles binds to NOF (ligand blotting) and inhibits the neurite promoting activity of NOF (inhibition assay). The 82-kD protein (NOF binding protein) was purified from gizzard muscle membranes as a doublet band on SDS-PAGE and a polyclonal antibody was raised against it. An NOF binding protein in developing retina exhibited the same physicochemical properties as that of the gizzard muscle. Quantitative decrease in NOF binding protein in embryonic retinas was observed after day 11 by the inhibition assay, ligand blotting, and immunoblotting, its decrease being parallel with reduction of NOF-induced neurite outgrowth of embryonic retinas. In an immunohistochemical study, the antibody stained only the optic fiber layers of the retinas of 8-d embryos, and this staining was no longer detectable in retinas of 18-d embryos. These results suggest that the 82-kD protein is a novel membrane protein that behaves as an NOF receptor and that the loss of neuritic response of the retinal neurons to NOF reflects a decrease in NOF receptor molecules.

Possible involvement of neurite outgrowth factor (NOF) receptor in axonal outgrowth from developing chick retina

We report that an 82-kDa membrane protein from chicken gizzard muscles is a neurite outgrowth factor (NOF)-receptor interacting with a domain for neurite-promoting activity of NOF. We found that an 82-kDa membrane protein in the developing chicken retina exhibited the same properties as those of gizzard muscles. The neuritic response of the retinal neurons to NOF increased in 6- and 8-day embryos, reaching a maximum level on the 8th-day and then rapidly decreased with aging. In parallel with this, the amount of NOF receptor in the retinas was maximal in 8- and 11-day embryos and thereafter decreased with aging. The results suggest that the failure in the neuritic response of the retinal neurons to NOF with aging is due to the decrease in NOF receptor.

Interaction of monoclonal antibodies with a neurite outgrowth factor from chicken gizzard extract

A neurite outgrowth factor (NOF), which promotes neurite outgrowth of cultured peripheral neurons, was purified to homogeneity from chicken gizzard extract and used as an immunogen for generating monoclonal antibodies. From 603 hybridoma clones, 55 positive hybridoma cell lines were detected. Four of them (IgG1 (kappa-chain) producers designated as 5-10A, M1-2G, 4-2C and 1-4D) were selected for further characterization. These antibodies immunoprecipitated 125I-labelled gizzard NOF molecules, whereas they did not inhibit the biological activity of NOF (or NOF-like molecules) derived from the tissues tested. The subcellular distribution of NOF in chick embryonal tissues was investigated using monoclonal antibody 4-2C. Both ciliary ganglionic (CG) neurons and gizzard muscle tissues were stained. The NOF content of embryonic CG, measured by an immunoblot assay, increased about 20-fold during embryogenesis from 6 to 15 days, whereas the sensitivity of neurons to NOF reciprocally decreased. At least two different sizes of NOFs (700 and 800 kDa) were found in CG of various ages, with the 800/700 kDa ratio gradually increasing with age. A mixture of these 4 monoclonal antibodies was used for immunoaffinity purification of NOF from chicken gizzard muscles.

A proteolytic 140-kDa fragment of neurite outgrowth factor and its cell-binding activity

A neurite outgrowth factor (NOF) from chicken gizzard was treated with elastase, and a protease-resistant fragment of 140 kDa (F-140) with heparin-binding activity, was isolated from the digested mixture. Although F-140 showed no neurite outgrowth activity, it could bind dissociated cells from the dorsal root ganglia of chick embryos. The antiserum to F-140 inhibited the cell binding activity of native NOF in a dose-dependent manner, but not the neurite outgrowth activity. When membrane proteins from whole chick embryos were incubated with NOF or F-140, a protein band of 41 kDa was detected as a major NOF-binding component.

Neurite-promoting activity from fetal skeletal muscle: immunological comparison with laminin

Polycation-binding neurite-promoting factor (PNPF) from skeletal muscle of bovine fetuses has been compared to mouse tumor laminin by an immunological approach. Antiserum prepared against PNPF blocked the neurite-promoting activity in a dose-dependent manner. The anti-PNPF antiserum bound to Mr = 200,000-195,000 bands as well as several components of higher molecular weight, as detected in immunoblots of reduced PNPF. The anti-PNPF antiserum did not inhibit the neurite-promoting activity of mouse laminin, although it did bind to native laminin. Antilaminin antiserum bound to PNFP and identified the same Mr = 200,000-195,000 bands and two other higher-molecular-weight bands, as did the anti-PNPF antiserum. The activity of PNPF was confirmed to be sensitive to treatment with heparitinase. It is concluded that PNPF from bovine fetal muscle contains a complex of heparan sulfate and high-molecular-weight components, particularly of Mr = 200,000-195,000, which share antigenic determinants with mouse laminin. However antilaminin antiserum fails to inhibit the activity of PNPF, suggesting that the active site, and/or adjacent regions, of PNPF are antigenically different from the neurite-promoting site of purified mouse tumor laminin.

Neurotrophic factors

In addition to nerve growth factor (NGF), many proteins present in soluble tissue extracts and in the extracellular matrix influence the survival and development of cultured neurons. The structure, synthesis, and mechanism of action of NGF as a neurotrophic factor are considered along with the experiments on the new putative trophic molecules.