NFASC Antibody

What is Neurofascin (NFASC) and what are its key functions in the nervous system?

Neurofascin belongs to the L1 subgroup of the immunoglobulin superfamily of cell adhesion molecules and functions as an axon-associated surface glycoprotein. It plays critical roles in axonal growth and fasciculation, serving as a fundamental component in maintaining neuronal architecture and function . The protein is integrally involved in multiple processes including neurite extension, axonal guidance, synaptogenesis, myelination, and neuron-glial cell interactions . Particularly important is Neurofascin's interaction with various proteins that reinforces the organization of the nodes of Ranvier, which is essential for stable and rapid signal conduction throughout both the peripheral and central nervous systems . This organization is crucial for saltatory conduction, the process by which action potentials jump between nodes, significantly increasing conduction velocity in myelinated axons.

What is the structural composition of Neurofascin?

Neurofascin possesses a complex structure comprised of four distinct structural elements. At the amino (NH₂) terminus, Neurofascin contains six immunoglobulin-like motifs of the C2 subcategory, which are followed by four fibronectin type III (FNIII)-related repeats . Between these FNIII-like repeats and the plasma membrane spanning region, Neurofascin features a 75-amino acid segment rich in proline, alanine, and threonine residues . This region is potentially subject to extensive O-linked glycosylation, which contributes to the protein's functional properties and interactions. The structural organization of Neurofascin enables it to engage in specific protein-protein interactions necessary for its roles in axonal development and function, with different domains mediating distinct molecular associations.

What are the main isoforms of Neurofascin and how do they differ functionally?

There are several isoforms of Neurofascin, with the neuronal isoform NF186 and the glial isoform NF155 being particularly important in research contexts. These isoforms have distinct functional roles and cellular localizations. The NF155 isoform is specifically expressed in glial cells and contains unique epitopes localized around the extracellular FN3 domain that are not present in the neuronal NF186 isoform . This structural difference is critically important for antibody specificity, as sera from NF155-positive CIDP patients bind specifically to the paranodal regions of peripheral nerves but do not react with the neuronal NF186 . This selective binding indicates that paranodes are the primary targets of autoantibodies in certain neurological conditions, highlighting the importance of understanding isoform-specific functions when designing experiments or interpreting clinical findings.

What experimental applications are NFASC antibodies suitable for?

Based on the available research, NFASC antibodies have been validated for multiple experimental applications. These include Western blotting (WB), immunohistochemistry on paraffin-embedded tissues (IHC-P), immunohistochemistry on frozen sections (IHC-fro), immunofluorescence on cultured cells (IF-cc), immunofluorescence on tissue sections (IF-p), immunocytochemistry (ICC), enzyme-linked immunosorbent assay (ELISA), and immunoprecipitation (IP) . The specific Anti-Neurofascin Antibody (AIP-025) has been successfully employed at dilutions of 1:800 for Western blot analysis and 1:200 for immunohistochemical staining of perfusion-fixed frozen rat brain sections . Similarly, another antibody (ab183082) has been used at a 1:400 dilution for Western blotting of human lung tissue lysate and 1:30 for immunohistochemical analysis of paraffin-embedded human brain tissue . When selecting an antibody for a particular application, researchers should consider both the validated applications and the optimal dilutions reported in the literature.

How can specificity of anti-NFASC antibodies be validated for research applications?

Validating antibody specificity is crucial for ensuring reliable experimental results. For anti-NFASC antibodies, several validation methods have been demonstrated in the literature. One effective approach is the use of blocking peptides, as shown with the Neurofascin Blocking Peptide (BLP-IP025) . Pre-incubation of the anti-Neurofascin antibody with this blocking peptide effectively suppressed staining in immunohistochemical analyses of both rat spinal cord and mouse hippocampus sections, confirming specificity . Additionally, comparison of staining patterns between antibodies targeting different epitopes of NFASC can provide further validation. The distinctive patterns of immunoreactivity observed in different tissues, such as the dense staining in the dorsal horn and sparse staining in the dorsal column of rat spinal cord, or the specific staining in the hippocampal dentate gyrus region, particularly in the hilus and outer layer, serve as characteristic signatures that can help confirm specificity .

What are the optimal protocols for using anti-NFASC antibodies in Western blot analysis?

For Western blot analysis using anti-NFASC antibodies, several protocol considerations are important for optimal results. Based on published methodologies, researchers should prepare lysates from relevant tissues such as rat brain, mouse brain, rat hippocampus, or human lung tissue . For the Anti-Neurofascin Antibody (AIP-025), a dilution of 1:800 has been validated for Western blotting , while the ab183082 antibody has been successfully used at 1:400 dilution . The predicted band size for Neurofascin is approximately 150 kDa . For detection, a secondary antibody such as goat anti-rabbit IgG conjugated with horseradish peroxidase (HRP) at a dilution of 1:5000 is recommended, followed by development using the ECL technique . Exposure times around 1 minute have yielded clear results. To confirm specificity, parallel samples can be run with the antibody pre-incubated with a blocking peptide, which should result in absence or significant reduction of the specific band.

How do anti-NF155 antibodies contribute to the pathophysiology of CIDP?

Anti-NF155 antibody-positive chronic inflammatory demyelinating polyneuropathy (CIDP) represents a distinct subtype with unique pathophysiological mechanisms. Research indicates that sera from NF155-positive CIDP patients bind specifically to the paranodal regions of peripheral nerves, identifying these structures as primary targets of the autoantibodies . The autoantibodies specifically recognize epitopes located around the extracellular FN3 domain unique to NF155, not present in the neuronal isoform NF186 . This selective targeting disrupts the integrity of paranodal junctions, compromising saltatory conduction. Notably, anti-NF155 antibody-positive CIDP is characterized by a high frequency of subclinical demyelinating lesions in the central nervous system (CNS), suggesting that the pathological process extends beyond the peripheral nervous system . This finding highlights the complex interplay between central and peripheral nervous system manifestations in this condition and underscores the importance of considering both systems when studying the disease mechanism.

What are the differences in detection rates of NF155 antibodies across different populations?

Significant variations exist in the detection rates of anti-NF155 antibodies across different populations, which has important implications for research design and interpretation. Initial measurements using enzyme-linked immunosorbent assays (ELISAs) revealed low positivity rates for human NF155 of 2.5% and 3.8%, while a higher 22% positivity rate was reported for rat NF155 . More specific antibody assays using human NF155 and flow cytometry showed positivity rates of 18% (9/50) in Japanese patients with CIDP, compared to 0% (0/32) in multiple sclerosis patients, 2.5% (1/40) in patients with other neuropathies, and 0% (0/30) in healthy control subjects . Similarly high frequencies have been reported in Chinese patients, with a 21% positivity rate . In contrast, European studies have shown significantly lower prevalence, with only 1% (15/1,500) positivity by flow cytometry and 3% (10/342) by cell-based assay and ELISA . These findings suggest that anti-NF155 antibodies are more prevalent in East-Asian populations than in European populations, which has important implications for study design, patient stratification, and interpretation of results in research involving these antibodies.

What cytokine profiles are associated with NF155-positive CIDP compared to NF155-negative CIDP?

Research has revealed distinct cytokine and chemokine profiles that differentiate NF155-positive CIDP from NF155-negative CIDP, providing valuable insights into the underlying pathogenic mechanisms. In NF155-positive CIDP, levels of CXCL8/interleukin 8 (IL8), IL13, tumor necrosis factor alpha (TNFα), CCL11/eotaxin, CCL2/MCP1, and IFNγ were significantly elevated compared to non-inflammatory neurological diseases (NIND) . Conversely, levels of IL1β, IL1ra, and GCSF were significantly reduced . When directly comparing NF155-positive and NF155-negative CIDP, the levels of CXCL8/IL8 and IL13 were significantly higher in NF155-positive patients, while IL1β, IL1ra, and IL6 levels were significantly lower . Notably, several cytokines and chemokines (CXCL8/IL8, IL13, CCL11/eotaxin, CXCL10/IP10, CCL3/MIP1α, CCL4/MIP1β, and TNFα) showed positive correlations with the markedly elevated cerebrospinal fluid (CSF) protein levels characteristic of NF155-positive CIDP . Additionally, IL13, CCL11/eotaxin, and IL17 levels correlated positively with increased CSF cell counts . This distinctive inflammatory profile suggests different immunopathological mechanisms in NF155-positive versus NF155-negative CIDP, which may have implications for therapeutic targeting and patient stratification.

How can NFASC antibodies be used to study the organization of nodes of Ranvier?

NFASC antibodies offer powerful tools for investigating the complex organization of nodes of Ranvier, which are crucial for saltatory conduction in myelinated axons. Researchers can employ immunohistochemical approaches with anti-NFASC antibodies to visualize the distribution and localization of Neurofascin at nodes and paranodes . For example, staining with Anti-Neurofascin Antibody (AIP-025) at a dilution of 1:200, followed by visualization with goat anti-rabbit-AlexaFluor-488, has revealed distinctive patterns of Neurofascin immunoreactivity in rat spinal cord, with dense staining in the dorsal horn and sparse staining in the dorsal column . Similar approaches can be applied to study nodal and paranodal structures in various neuronal tissues. The specificity of such staining can be confirmed through pre-incubation with blocking peptides, which should suppress the signal . By combining NFASC antibodies with antibodies against other nodal and paranodal proteins, researchers can develop a comprehensive understanding of nodal architecture and how it may be disrupted in various pathological conditions, particularly those involving demyelination or disruption of axo-glial junctions.

What are the best approaches for targeting specific epitopes within NFASC for research purposes?

Several commercial antibodies are available that target different epitopes within the NFASC protein, allowing researchers to investigate isoform-specific functions and interactions. These include antibodies targeting: the C-terminal intracellular region (amino acids 1142-1155) , regions within amino acids 1200 to the C-terminus , amino acids 501-650 , amino acids 830-1100 , amino acids 661-758 , and amino acids 760-1007 . When selecting an antibody for a specific research question, consideration should be given to which domain or epitope is most relevant. For instance, antibodies targeting the FN3 domain unique to NF155 would be particularly useful for studying NF155-specific functions or pathologies like NF155-positive CIDP . Conversely, antibodies targeting regions common to multiple isoforms would be appropriate for more general studies of Neurofascin function. The choice of antibody should also be guided by the species of interest, as different antibodies have been validated for human, mouse, and rat samples . Additionally, the intended application (Western blot, immunohistochemistry, etc.) should inform antibody selection, as not all antibodies are suitable for all applications.

How do central and peripheral nervous system manifestations differ in anti-NF155 antibody-positive conditions?

Anti-NF155 antibody-positive CIDP presents with a unique clinical and pathological profile that encompasses both peripheral and central nervous system manifestations. A distinguishing feature of this condition is the high frequency of subclinical demyelinating lesions in the central nervous system, which sets it apart from other forms of CIDP that primarily affect peripheral nerves . This dual involvement suggests that the pathogenic autoantibodies may target Neurofascin in both peripheral and central myelin structures. The central nervous system involvement in NF155-positive CIDP is further evidenced by distinctive cerebrospinal fluid findings, including elevated protein levels and increased cell counts that correlate with specific cytokine and chemokine profiles . This contrasts with the predominantly peripheral manifestations seen in NF155-negative CIDP. Understanding these differential manifestations is crucial for comprehensive investigation of the disease mechanisms and for developing targeted therapeutic approaches. Researchers studying this condition should consider incorporating both peripheral nerve and central nervous system assessments in their experimental designs to capture the full spectrum of pathology.